diff --git a/ChangeLog b/ChangeLog
index 5f5fdd2..70e9bb6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,14 @@
      trusted CA with a non DER-compliant certificate. Found by luocm on GitHub.
      Fixes #825.
 
+API changes
+   * Add function mbedtls_net_poll to public API allowing to wait for a
+     network context to become ready for reading or writing.
+   * Add function mbedtls_ssl_check_pending to public API allowing to check
+     if more data is pending to be processed in the internal message buffers.
+     This function is necessary to determine when it is safe to idle on the
+     underlying transport in case event-driven IO is used.
+
 Bugfix
    * Fix spurious uninitialized variable warning in cmac.c. Fix independently
      contributed by Brian J Murray and David Brown.
@@ -18,6 +26,14 @@
      Fixes #1040.
    * Fix C89 incompatibility in benchmark.c. Contributed by Brendan Shanks.
      #1353
+   * Restrict usage of error code MBEDTLS_ERR_SSL_WANT_READ to situations
+     where data needs to be fetched from the underlying transport in order
+     to make progress. Previously, this error code was also occasionally
+     returned when unexpected messages were being discarded, ignoring that
+     further messages could potentially already be pending to be processed
+     in the internal buffers; these cases lead to deadlocks in case
+     event-driven I/O was used.
+     Found and reported by Hubert Mis in #772.
 
 Changes
    * Remove some redundant code in bignum.c. Contributed by Alexey Skalozub.
@@ -310,6 +326,7 @@
      implementation.
    * Add explicit warnings for the use of MD2, MD4, MD5, SHA-1, DES and ARC4
      throughout the library.
+>>>>>>> development
 
 = mbed TLS 2.6.0 branch released 2017-08-10
 
diff --git a/include/mbedtls/net_sockets.h b/include/mbedtls/net_sockets.h
index 54e612c..c5e83d5 100644
--- a/include/mbedtls/net_sockets.h
+++ b/include/mbedtls/net_sockets.h
@@ -46,12 +46,17 @@
 #define MBEDTLS_ERR_NET_UNKNOWN_HOST                      -0x0052  /**< Failed to get an IP address for the given hostname. */
 #define MBEDTLS_ERR_NET_BUFFER_TOO_SMALL                  -0x0043  /**< Buffer is too small to hold the data. */
 #define MBEDTLS_ERR_NET_INVALID_CONTEXT                   -0x0045  /**< The context is invalid, eg because it was free()ed. */
+#define MBEDTLS_ERR_NET_POLL_FAILED                       -0x0047  /**< Polling the net context failed. */
+#define MBEDTLS_ERR_NET_BAD_INPUT_DATA                    -0x0049  /**< Input invalid. */
 
 #define MBEDTLS_NET_LISTEN_BACKLOG         10 /**< The backlog that listen() should use. */
 
 #define MBEDTLS_NET_PROTO_TCP 0 /**< The TCP transport protocol */
 #define MBEDTLS_NET_PROTO_UDP 1 /**< The UDP transport protocol */
 
+#define MBEDTLS_NET_POLL_READ  1 /**< Used in \c mbedtls_net_poll to check for pending data  */
+#define MBEDTLS_NET_POLL_WRITE 2 /**< Used in \c mbedtls_net_poll to check if write possible */
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -133,6 +138,29 @@
                         void *client_ip, size_t buf_size, size_t *ip_len );
 
 /**
+ * \brief          Check and wait for the context to be ready for read/write
+ *
+ * \param ctx      Socket to check
+ * \param rw       Bitflag composed of MBEDTLS_NET_POLL_READ and
+ *                 MBEDTLS_NET_POLL_WRITE specifying the events
+ *                 to wait for:
+ *                 - If MBEDTLS_NET_POLL_READ is set, the function
+ *                   will return as soon as the net context is available
+ *                   for reading.
+ *                 - If MBEDTLS_NET_POLL_WRITE is set, the function
+ *                   will return as soon as the net context is available
+ *                   for writing.
+ * \param timeout  Maximal amount of time to wait before returning,
+ *                 in milliseconds. If \c timeout is zero, the
+ *                 function returns immediately. If \c timeout is
+ *                 -1u, the function blocks potentially indefinitely.
+ *
+ * \return         Bitmask composed of MBEDTLS_NET_POLL_READ/WRITE
+ *                 on success or timeout, or a negative return code otherwise.
+ */
+int mbedtls_net_poll( mbedtls_net_context *ctx, uint32_t rw, uint32_t timeout );
+
+/**
  * \brief          Set the socket blocking
  *
  * \param ctx      Socket to set
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 401a127..e5b96c9 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -112,13 +112,14 @@
 #define MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED             -0x6A80  /**< DTLS client must retry for hello verification */
 #define MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL                  -0x6A00  /**< A buffer is too small to receive or write a message */
 #define MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE             -0x6980  /**< None of the common ciphersuites is usable (eg, no suitable certificate, see debug messages). */
-#define MBEDTLS_ERR_SSL_WANT_READ                         -0x6900  /**< Connection requires a read call. */
+#define MBEDTLS_ERR_SSL_WANT_READ                         -0x6900  /**< No data of requested type currently available on underlying transport. */
 #define MBEDTLS_ERR_SSL_WANT_WRITE                        -0x6880  /**< Connection requires a write call. */
 #define MBEDTLS_ERR_SSL_TIMEOUT                           -0x6800  /**< The operation timed out. */
 #define MBEDTLS_ERR_SSL_CLIENT_RECONNECT                  -0x6780  /**< The client initiated a reconnect from the same port. */
 #define MBEDTLS_ERR_SSL_UNEXPECTED_RECORD                 -0x6700  /**< Record header looks valid but is not expected. */
 #define MBEDTLS_ERR_SSL_NON_FATAL                         -0x6680  /**< The alert message received indicates a non-fatal error. */
 #define MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH               -0x6600  /**< Couldn't set the hash for verifying CertificateVerify */
+#define MBEDTLS_ERR_SSL_CONTINUE_PROCESSING               -0x6580  /**< Internal-only message signaling that further message-processing should be done */
 
 /*
  * Various constants
@@ -2293,11 +2294,59 @@
 #endif /* MBEDTLS_SSL_RENEGOTIATION */
 
 /**
- * \brief          Return the number of data bytes available to read
+ * \brief          Check if there is data already read from the
+ *                 underlying transport but not yet processed.
  *
  * \param ssl      SSL context
  *
- * \return         how many bytes are available in the read buffer
+ * \return         0 if nothing's pending, 1 otherwise.
+ *
+ * \note           This is different in purpose and behaviour from
+ *                 \c mbedtls_ssl_get_bytes_avail in that it considers
+ *                 any kind of unprocessed data, not only unread
+ *                 application data. If \c mbedtls_ssl_get_bytes
+ *                 returns a non-zero value, this function will
+ *                 also signal pending data, but the converse does
+ *                 not hold. For example, in DTLS there might be
+ *                 further records waiting to be processed from
+ *                 the current underlying transport's datagram.
+ *
+ * \note           If this function returns 1 (data pending), this
+ *                 does not imply that a subsequent call to
+ *                 \c mbedtls_ssl_read will provide any data;
+ *                 e.g., the unprocessed data might turn out
+ *                 to be an alert or a handshake message.
+ *
+ * \note           This function is useful in the following situation:
+ *                 If the SSL/TLS module successfully returns from an
+ *                 operation - e.g. a handshake or an application record
+ *                 read - and you're awaiting incoming data next, you
+ *                 must not immediately idle on the underlying transport
+ *                 to have data ready, but you need to check the value
+ *                 of this function first. The reason is that the desired
+ *                 data might already be read but not yet processed.
+ *                 If, in contrast, a previous call to the SSL/TLS module
+ *                 returned MBEDTLS_ERR_SSL_WANT_READ, it is not necessary
+ *                 to call this function, as the latter error code entails
+ *                 that all internal data has been processed.
+ *
+ */
+int mbedtls_ssl_check_pending( const mbedtls_ssl_context *ssl );
+
+/**
+ * \brief          Return the number of application data bytes
+ *                 remaining to be read from the current record.
+ *
+ * \param ssl      SSL context
+ *
+ * \return         How many bytes are available in the application
+ *                 data record read buffer.
+ *
+ * \note           When working over a datagram transport, this is
+ *                 useful to detect the current datagram's boundary
+ *                 in case \c mbedtls_ssl_read has written the maximal
+ *                 amount of data fitting into the input buffer.
+ *
  */
 size_t mbedtls_ssl_get_bytes_avail( const mbedtls_ssl_context *ssl );
 
@@ -2412,11 +2461,25 @@
  *                 MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED (see below), or
  *                 a specific SSL error code.
  *
+ *                 If this function returns MBEDTLS_ERR_SSL_WANT_READ, the
+ *                 handshake is unfinished and no further data is available
+ *                 from the underlying transport. In this case, you must call
+ *                 the function again at some later stage.
+ *
+ * \note           Remarks regarding event-driven DTLS:
+ *                 If the function returns MBEDTLS_ERR_SSL_WANT_READ, no datagram
+ *                 from the underlying transport layer is currently being processed,
+ *                 and it is safe to idle until the timer or the underlying transport
+ *                 signal a new event. This is not true for a successful handshake,
+ *                 in which case the datagram of the underlying transport that is
+ *                 currently being processed might or might not contain further
+ *                 DTLS records.
+ *
  * \note           If this function returns something other than 0 or
- *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, then the ssl context
- *                 becomes unusable, and you should either free it or call
- *                 \c mbedtls_ssl_session_reset() on it before re-using it for
- *                 a new connection; the current connection must be closed.
+ *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
+ *                 the SSL context for reading or writing, and either free it or
+ *                 call \c mbedtls_ssl_session_reset() on it before re-using it
+ *                 for a new connection; the current connection must be closed.
  *
  * \note           If DTLS is in use, then you may choose to handle
  *                 MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED specially for logging
@@ -2433,10 +2496,10 @@
  *                 call this function if state is MBEDTLS_SSL_HANDSHAKE_OVER.
  *
  * \note           If this function returns something other than 0 or
- *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, then the ssl context
- *                 becomes unusable, and you should either free it or call
- *                 \c mbedtls_ssl_session_reset() on it before re-using it for
- *                 a new connection; the current connection must be closed.
+ *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
+ *                 the SSL context for reading or writing, and either free it or
+ *                 call \c mbedtls_ssl_session_reset() on it before re-using it
+ *                 for a new connection; the current connection must be closed.
  *
  * \param ssl      SSL context
  *
@@ -2460,10 +2523,10 @@
  *                 value.
  *
  * \note           If this function returns something other than 0 or
- *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, then the ssl context
- *                 becomes unusable, and you should either free it or call
- *                 \c mbedtls_ssl_session_reset() on it before re-using it for
- *                 a new connection; the current connection must be closed.
+ *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
+ *                 the SSL context for reading or writing, and either free it or
+ *                 call \c mbedtls_ssl_session_reset() on it before re-using it
+ *                 for a new connection; the current connection must be closed.
  */
 int mbedtls_ssl_renegotiate( mbedtls_ssl_context *ssl );
 #endif /* MBEDTLS_SSL_RENEGOTIATION */
@@ -2475,20 +2538,20 @@
  * \param buf      buffer that will hold the data
  * \param len      maximum number of bytes to read
  *
- * \return         the number of bytes read, or
- *                 0 for EOF, or
- *                 MBEDTLS_ERR_SSL_WANT_READ or MBEDTLS_ERR_SSL_WANT_WRITE, or
- *                 MBEDTLS_ERR_SSL_CLIENT_RECONNECT (see below), or
- *                 another negative error code.
+ * \return         One of the following:
+ *                 - 0 if the read end of the underlying transport was closed,
+ *                 - the (positive) number of bytes read, or
+ *                 - a negative error code on failure.
  *
- * \note           If this function returns something other than a positive
- *                 value or MBEDTLS_ERR_SSL_WANT_READ/WRITE or
- *                 MBEDTLS_ERR_SSL_CLIENT_RECONNECT, then the ssl context
- *                 becomes unusable, and you should either free it or call
- *                 \c mbedtls_ssl_session_reset() on it before re-using it for
- *                 a new connection; the current connection must be closed.
+ *                 If MBEDTLS_ERR_SSL_WANT_READ is returned, no application data
+ *                 is available from the underlying transport. In this case,
+ *                 the function needs to be called again at some later stage.
  *
- * \note           When this function return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
+ *                 If MBEDTLS_ERR_SSL_WANT_WRITE is returned, a write is pending
+ *                 but the underlying transport isn't available for writing. In this
+ *                 case, the function needs to be called again at some later stage.
+ *
+ *                 When this function return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
  *                 (which can only happen server-side), it means that a client
  *                 is initiating a new connection using the same source port.
  *                 You can either treat that as a connection close and wait
@@ -2501,6 +2564,28 @@
  *                 again. WARNING: not validating the identity of the client
  *                 again, or not transmitting the new identity to the
  *                 application layer, would allow authentication bypass!
+ *
+ * \note           If this function returns something other than a positive value
+ *                 or MBEDTLS_ERR_SSL_WANT_READ/WRITE or MBEDTLS_ERR_SSL_CLIENT_RECONNECT,
+ *                 you must stop using the SSL context for reading or writing,
+ *                 and either free it or call \c mbedtls_ssl_session_reset() on it
+ *                 before re-using it for a new connection; the current connection
+ *                 must be closed.
+ *
+ * \note           Remarks regarding event-driven DTLS:
+ *                 - If the function returns MBEDTLS_ERR_SSL_WANT_READ, no datagram
+ *                   from the underlying transport layer is currently being processed,
+ *                   and it is safe to idle until the timer or the underlying transport
+ *                   signal a new event.
+ *                 - This function may return MBEDTLS_ERR_SSL_WANT_READ even if data was
+ *                   initially available on the underlying transport, as this data may have
+ *                   been only e.g. duplicated messages or a renegotiation request.
+ *                   Therefore, you must be prepared to receive MBEDTLS_ERR_SSL_WANT_READ even
+ *                   when reacting to an incoming-data event from the underlying transport.
+ *                 - On success, the datagram of the underlying transport that is currently
+ *                   being processed may contain further DTLS records. You should call
+ *                   \c mbedtls_ssl_check_pending to check for remaining records.
+ *
  */
 int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len );
 
@@ -2521,11 +2606,11 @@
  *                 or MBEDTLS_ERR_SSL_WANT_WRITE or MBEDTLS_ERR_SSL_WANT_READ,
  *                 or another negative error code.
  *
- * \note           If this function returns something other than a positive
- *                 value or MBEDTLS_ERR_SSL_WANT_READ/WRITE, the ssl context
- *                 becomes unusable, and you should either free it or call
- *                 \c mbedtls_ssl_session_reset() on it before re-using it for
- *                 a new connection; the current connection must be closed.
+ * \note           If this function returns something other than a positive value
+ *                 or MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
+ *                 the SSL context for reading or writing, and either free it or
+ *                 call \c mbedtls_ssl_session_reset() on it before re-using it
+ *                 for a new connection; the current connection must be closed.
  *
  * \note           When this function returns MBEDTLS_ERR_SSL_WANT_WRITE/READ,
  *                 it must be called later with the *same* arguments,
@@ -2552,10 +2637,10 @@
  * \return          0 if successful, or a specific SSL error code.
  *
  * \note           If this function returns something other than 0 or
- *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, then the ssl context
- *                 becomes unusable, and you should either free it or call
- *                 \c mbedtls_ssl_session_reset() on it before re-using it for
- *                 a new connection; the current connection must be closed.
+ *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
+ *                 the SSL context for reading or writing, and either free it or
+ *                 call \c mbedtls_ssl_session_reset() on it before re-using it
+ *                 for a new connection; the current connection must be closed.
  */
 int mbedtls_ssl_send_alert_message( mbedtls_ssl_context *ssl,
                             unsigned char level,
@@ -2568,10 +2653,10 @@
  * \return          0 if successful, or a specific SSL error code.
  *
  * \note           If this function returns something other than 0 or
- *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, then the ssl context
- *                 becomes unusable, and you should either free it or call
- *                 \c mbedtls_ssl_session_reset() on it before re-using it for
- *                 a new connection; the current connection must be closed.
+ *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
+ *                 the SSL context for reading or writing, and either free it or
+ *                 call \c mbedtls_ssl_session_reset() on it before re-using it
+ *                 for a new connection; the current connection must be closed.
  */
 int mbedtls_ssl_close_notify( mbedtls_ssl_context *ssl );
 
diff --git a/library/error.c b/library/error.c
index 0292480..b41f7fd 100644
--- a/library/error.c
+++ b/library/error.c
@@ -478,7 +478,7 @@
         if( use_ret == -(MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE) )
             mbedtls_snprintf( buf, buflen, "SSL - None of the common ciphersuites is usable (eg, no suitable certificate, see debug messages)" );
         if( use_ret == -(MBEDTLS_ERR_SSL_WANT_READ) )
-            mbedtls_snprintf( buf, buflen, "SSL - Connection requires a read call" );
+            mbedtls_snprintf( buf, buflen, "SSL - No data of requested type currently available on underlying transport" );
         if( use_ret == -(MBEDTLS_ERR_SSL_WANT_WRITE) )
             mbedtls_snprintf( buf, buflen, "SSL - Connection requires a write call" );
         if( use_ret == -(MBEDTLS_ERR_SSL_TIMEOUT) )
@@ -491,6 +491,8 @@
             mbedtls_snprintf( buf, buflen, "SSL - The alert message received indicates a non-fatal error" );
         if( use_ret == -(MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH) )
             mbedtls_snprintf( buf, buflen, "SSL - Couldn't set the hash for verifying CertificateVerify" );
+        if( use_ret == -(MBEDTLS_ERR_SSL_CONTINUE_PROCESSING) )
+            mbedtls_snprintf( buf, buflen, "SSL - Internal-only message signaling that further message-processing should be done" );
 #endif /* MBEDTLS_SSL_TLS_C */
 
 #if defined(MBEDTLS_X509_USE_C) || defined(MBEDTLS_X509_CREATE_C)
@@ -745,6 +747,10 @@
         mbedtls_snprintf( buf, buflen, "NET - Buffer is too small to hold the data" );
     if( use_ret == -(MBEDTLS_ERR_NET_INVALID_CONTEXT) )
         mbedtls_snprintf( buf, buflen, "NET - The context is invalid, eg because it was free()ed" );
+    if( use_ret == -(MBEDTLS_ERR_NET_POLL_FAILED) )
+        mbedtls_snprintf( buf, buflen, "NET - Polling the net context failed" );
+    if( use_ret == -(MBEDTLS_ERR_NET_BAD_INPUT_DATA) )
+        mbedtls_snprintf( buf, buflen, "NET - Input invalid" );
 #endif /* MBEDTLS_NET_C */
 
 #if defined(MBEDTLS_OID_C)
diff --git a/library/net_sockets.c b/library/net_sockets.c
index 631efad..cdc2376 100644
--- a/library/net_sockets.c
+++ b/library/net_sockets.c
@@ -45,6 +45,8 @@
 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
     !defined(EFI32)
 
+#define IS_EINTR( ret ) ( ( ret ) == WSAEINTR )
+
 #ifdef _WIN32_WINNT
 #undef _WIN32_WINNT
 #endif
@@ -82,6 +84,8 @@
 #include <netdb.h>
 #include <errno.h>
 
+#define IS_EINTR( ret ) ( ( ret ) == EINTR )
+
 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
 
 /* Some MS functions want int and MSVC warns if we pass size_t,
@@ -439,6 +443,62 @@
 }
 
 /*
+ * Check if data is available on the socket
+ */
+
+int mbedtls_net_poll( mbedtls_net_context *ctx, uint32_t rw, uint32_t timeout )
+{
+    int ret;
+    struct timeval tv;
+
+    fd_set read_fds;
+    fd_set write_fds;
+
+    int fd = ctx->fd;
+
+    if( fd < 0 )
+        return( MBEDTLS_ERR_NET_INVALID_CONTEXT );
+
+    FD_ZERO( &read_fds );
+    if( rw & MBEDTLS_NET_POLL_READ )
+    {
+        rw &= ~MBEDTLS_NET_POLL_READ;
+        FD_SET( fd, &read_fds );
+    }
+
+    FD_ZERO( &write_fds );
+    if( rw & MBEDTLS_NET_POLL_WRITE )
+    {
+        rw &= ~MBEDTLS_NET_POLL_WRITE;
+        FD_SET( fd, &write_fds );
+    }
+
+    if( rw != 0 )
+        return( MBEDTLS_ERR_NET_BAD_INPUT_DATA );
+
+    tv.tv_sec  = timeout / 1000;
+    tv.tv_usec = ( timeout % 1000 ) * 1000;
+
+    do
+    {
+        ret = select( fd + 1, &read_fds, &write_fds, NULL,
+                      timeout == (uint32_t) -1 ? NULL : &tv );
+    }
+    while( IS_EINTR( ret ) );
+
+    if( ret < 0 )
+        return( MBEDTLS_ERR_NET_POLL_FAILED );
+
+    ret = 0;
+    if( FD_ISSET( fd, &read_fds ) )
+        ret |= MBEDTLS_NET_POLL_READ;
+    if( FD_ISSET( fd, &write_fds ) )
+        ret |= MBEDTLS_NET_POLL_WRITE;
+
+    return( ret );
+}
+
+/*
  * Portable usleep helper
  */
 void mbedtls_net_usleep( unsigned long usec )
@@ -497,8 +557,8 @@
 /*
  * Read at most 'len' characters, blocking for at most 'timeout' ms
  */
-int mbedtls_net_recv_timeout( void *ctx, unsigned char *buf, size_t len,
-                      uint32_t timeout )
+int mbedtls_net_recv_timeout( void *ctx, unsigned char *buf,
+                              size_t len, uint32_t timeout )
 {
     int ret;
     struct timeval tv;
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index aca4235..2c180f1 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -793,7 +793,7 @@
     const mbedtls_ssl_ciphersuite_t *suite_info;
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
-    defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)    
+    defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
     mbedtls_pk_type_t sig_type;
 #endif
 
@@ -2961,7 +2961,7 @@
             return( ret );
         }
 
-#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)        
+#if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
         dig_signed = p;
         dig_signed_len = len;
 #endif
@@ -3050,7 +3050,7 @@
 
         /*
          * 3.1: Choose hash algorithm:
-         * A: For TLS 1.2, obey signature-hash-algorithm extension 
+         * A: For TLS 1.2, obey signature-hash-algorithm extension
          *    to choose appropriate hash.
          * B: For SSL3, TLS1.0, TLS1.1 and ECDHE_ECDSA, use SHA1
          *    (RFC 4492, Sec. 5.4)
@@ -3071,7 +3071,7 @@
                                                           sig_alg ) ) == MBEDTLS_MD_NONE )
             {
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
-                /* (... because we choose a cipher suite 
+                /* (... because we choose a cipher suite
                  *      only if there is a matching hash.) */
                 return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
             }
@@ -3750,7 +3750,10 @@
     /* Read the message without adding it to the checksum */
     do {
 
-        if( ( ret = mbedtls_ssl_read_record_layer( ssl ) ) != 0 )
+        do ret = mbedtls_ssl_read_record_layer( ssl );
+        while( ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
+
+        if( ret != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ssl_read_record_layer" ), ret );
             return( ret );
@@ -3758,7 +3761,8 @@
 
         ret = mbedtls_ssl_handle_message_type( ssl );
 
-    } while( MBEDTLS_ERR_SSL_NON_FATAL == ret );
+    } while( MBEDTLS_ERR_SSL_NON_FATAL           == ret ||
+             MBEDTLS_ERR_SSL_CONTINUE_PROCESSING == ret );
 
     if( 0 != ret )
     {
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 236e52d..f533c0b 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2332,7 +2332,10 @@
          * that will end up being dropped.
          */
         if( ssl_check_timer( ssl ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "timer has expired" ) );
             ret = MBEDTLS_ERR_SSL_TIMEOUT;
+        }
         else
         {
             len = MBEDTLS_SSL_BUFFER_LEN - ( ssl->in_hdr - ssl->in_buf );
@@ -3064,7 +3067,7 @@
     if( ssl_bitmask_check( bitmask, msg_len ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 2, ( "message is not complete yet" ) );
-        return( MBEDTLS_ERR_SSL_WANT_READ );
+        return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
     }
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "handshake message completed" ) );
@@ -3141,9 +3144,11 @@
         int ret;
         unsigned int recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
 
-        /* ssl->handshake is NULL when receiving ClientHello for renego */
         if( ssl->handshake != NULL &&
-            recv_msg_seq != ssl->handshake->in_msg_seq )
+            ( ( ssl->state   != MBEDTLS_SSL_HANDSHAKE_OVER &&
+                recv_msg_seq != ssl->handshake->in_msg_seq ) ||
+              ( ssl->state  == MBEDTLS_SSL_HANDSHAKE_OVER &&
+                ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO ) ) )
         {
             /* Retransmit only on last message from previous flight, to avoid
              * too many retransmissions.
@@ -3170,7 +3175,7 @@
                                     ssl->handshake->in_msg_seq ) );
             }
 
-            return( MBEDTLS_ERR_SSL_WANT_READ );
+            return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
         }
         /* Wait until message completion to increment in_msg_seq */
 
@@ -3573,81 +3578,23 @@
         return( MBEDTLS_ERR_SSL_INVALID_RECORD );
     }
 
-    /* Check length against bounds of the current transform and version */
-    if( ssl->transform_in == NULL )
-    {
-        if( ssl->in_msglen < 1 ||
-            ssl->in_msglen > MBEDTLS_SSL_MAX_CONTENT_LEN )
-        {
-            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
-            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
-        }
-    }
-    else
-    {
-        if( ssl->in_msglen < ssl->transform_in->minlen )
-        {
-            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
-            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
-        }
-
-#if defined(MBEDTLS_SSL_PROTO_SSL3)
-        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 &&
-            ssl->in_msglen > ssl->transform_in->minlen + MBEDTLS_SSL_MAX_CONTENT_LEN )
-        {
-            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
-            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
-        }
-#endif
-#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
-    defined(MBEDTLS_SSL_PROTO_TLS1_2)
-        /*
-         * TLS encrypted messages can have up to 256 bytes of padding
-         */
-        if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 &&
-            ssl->in_msglen > ssl->transform_in->minlen +
-                             MBEDTLS_SSL_MAX_CONTENT_LEN + 256 )
-        {
-            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
-            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
-        }
-#endif
-    }
-
     /*
-     * DTLS-related tests done last, because most of them may result in
-     * silently dropping the record (but not the whole datagram), and we only
-     * want to consider that after ensuring that the "basic" fields (type,
-     * version, length) are sane.
+     * DTLS-related tests.
+     * Check epoch before checking length constraint because
+     * the latter varies with the epoch. E.g., if a ChangeCipherSpec
+     * message gets duplicated before the corresponding Finished message,
+     * the second ChangeCipherSpec should be discarded because it belongs
+     * to an old epoch, but not because its length is shorter than
+     * the minimum record length for packets using the new record transform.
+     * Note that these two kinds of failures are handled differently,
+     * as an unexpected record is silently skipped but an invalid
+     * record leads to the entire datagram being dropped.
      */
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
     if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
     {
         unsigned int rec_epoch = ( ssl->in_ctr[0] << 8 ) | ssl->in_ctr[1];
 
-        /* Drop unexpected ChangeCipherSpec messages */
-        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
-            ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC &&
-            ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
-        {
-            MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ChangeCipherSpec" ) );
-            return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
-        }
-
-        /* Drop unexpected ApplicationData records,
-         * except at the beginning of renegotiations */
-        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
-            ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER
-#if defined(MBEDTLS_SSL_RENEGOTIATION)
-            && ! ( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
-                   ssl->state == MBEDTLS_SSL_SERVER_HELLO )
-#endif
-            )
-        {
-            MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ApplicationData" ) );
-            return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
-        }
-
         /* Check epoch (and sequence number) with DTLS */
         if( rec_epoch != ssl->in_epoch )
         {
@@ -3687,9 +3634,74 @@
             return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
         }
 #endif
+
+        /* Drop unexpected ChangeCipherSpec messages */
+        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
+            ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC &&
+            ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ChangeCipherSpec" ) );
+            return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
+        }
+
+        /* Drop unexpected ApplicationData records,
+         * except at the beginning of renegotiations */
+        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
+            ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+            && ! ( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
+                   ssl->state == MBEDTLS_SSL_SERVER_HELLO )
+#endif
+            )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ApplicationData" ) );
+            return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
+        }
     }
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
+
+    /* Check length against bounds of the current transform and version */
+    if( ssl->transform_in == NULL )
+    {
+        if( ssl->in_msglen < 1 ||
+            ssl->in_msglen > MBEDTLS_SSL_MAX_CONTENT_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+    }
+    else
+    {
+        if( ssl->in_msglen < ssl->transform_in->minlen )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+
+#if defined(MBEDTLS_SSL_PROTO_SSL3)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 &&
+            ssl->in_msglen > ssl->transform_in->minlen + MBEDTLS_SSL_MAX_CONTENT_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
+    defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        /*
+         * TLS encrypted messages can have up to 256 bytes of padding
+         */
+        if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 &&
+            ssl->in_msglen > ssl->transform_in->minlen +
+                             MBEDTLS_SSL_MAX_CONTENT_LEN + 256 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+#endif
+    }
+
     return( 0 );
 }
 
@@ -3778,7 +3790,10 @@
     {
         do {
 
-            if( ( ret = mbedtls_ssl_read_record_layer( ssl ) ) != 0 )
+            do ret = mbedtls_ssl_read_record_layer( ssl );
+            while( ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
+
+            if( ret != 0 )
             {
                 MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ssl_read_record_layer" ), ret );
                 return( ret );
@@ -3786,11 +3801,12 @@
 
             ret = mbedtls_ssl_handle_message_type( ssl );
 
-        } while( MBEDTLS_ERR_SSL_NON_FATAL == ret );
+        } while( MBEDTLS_ERR_SSL_NON_FATAL           == ret  ||
+                 MBEDTLS_ERR_SSL_CONTINUE_PROCESSING == ret );
 
         if( 0 != ret )
         {
-            MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ssl_read_record_layer" ), ret );
+            MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ssl_handle_message_type" ), ret );
             return( ret );
         }
 
@@ -3828,11 +3844,6 @@
      * (2) Alert messages:
      *     Consume whole record content, in_msglen = 0.
      *
-     *     NOTE: This needs to be fixed, since like for
-     *     handshake messages it is allowed to have
-     *     multiple alerts witin a single record.
-     *     Internal reference IOTSSL-1321.
-     *
      * (3) Change cipher spec:
      *     Consume whole record content, in_msglen = 0.
      *
@@ -3860,12 +3871,12 @@
          */
 
         /* Notes:
-         * (1) in_hslen is *NOT* necessarily the size of the
+         * (1) in_hslen is not necessarily the size of the
          *     current handshake content: If DTLS handshake
          *     fragmentation is used, that's the fragment
          *     size instead. Using the total handshake message
-         *     size here is FAULTY and should be changed at
-         *     some point. Internal reference IOTSSL-1414.
+         *     size here is faulty and should be changed at
+         *     some point.
          * (2) While it doesn't seem to cause problems, one
          *     has to be very careful not to assume that in_hslen
          *     is always <= in_msglen in a sensible communication.
@@ -3916,12 +3927,6 @@
         return( 0 );
     }
 
-    /* Need to fetch a new record */
-
-#if defined(MBEDTLS_SSL_PROTO_DTLS)
-read_record_header:
-#endif
-
     /* Current record either fully processed or to be discarded. */
 
     if( ( ret = mbedtls_ssl_fetch_input( ssl, mbedtls_ssl_hdr_len( ssl ) ) ) != 0 )
@@ -3956,7 +3961,7 @@
             }
 
             /* Get next record */
-            goto read_record_header;
+            return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
         }
 #endif
         return( ret );
@@ -3975,7 +3980,13 @@
     /* Done reading this record, get ready for the next one */
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
     if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+    {
         ssl->next_record_offset = ssl->in_msglen + mbedtls_ssl_hdr_len( ssl );
+        if( ssl->next_record_offset < ssl->in_left )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "more than one record within datagram" ) );
+        }
+    }
     else
 #endif
         ssl->in_left = 0;
@@ -4022,7 +4033,7 @@
                 ssl->in_left = 0;
 
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record (mac)" ) );
-                goto read_record_header;
+                return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
             }
 
             return( ret );
@@ -4043,46 +4054,6 @@
         }
     }
 
-    /*
-     * When we sent the last flight of the handshake, we MUST respond to a
-     * retransmit of the peer's previous flight with a retransmit. (In
-     * practice, only the Finished message will make it, other messages
-     * including CCS use the old transform so they're dropped as invalid.)
-     *
-     * If the record we received is not a handshake message, however, it
-     * means the peer received our last flight so we can clean up
-     * handshake info.
-     *
-     * This check needs to be done before prepare_handshake() due to an edge
-     * case: if the client immediately requests renegotiation, this
-     * finishes the current handshake first, avoiding the new ClientHello
-     * being mistaken for an ancient message in the current handshake.
-     */
-#if defined(MBEDTLS_SSL_PROTO_DTLS)
-    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
-        ssl->handshake != NULL &&
-        ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
-    {
-        if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
-                ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
-        {
-            MBEDTLS_SSL_DEBUG_MSG( 2, ( "received retransmit of last flight" ) );
-
-            if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
-            {
-                MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
-                return( ret );
-            }
-
-            return( MBEDTLS_ERR_SSL_WANT_READ );
-        }
-        else
-        {
-            ssl_handshake_wrapup_free_hs_transform( ssl );
-        }
-    }
-#endif
-
     return( 0 );
 }
 
@@ -4127,7 +4098,7 @@
         if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
             ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION )
         {
-            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no_cert" ) );
+            MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no renegotiation alert" ) );
             /* Will be handled when trying to parse ServerHello */
             return( 0 );
         }
@@ -4149,6 +4120,15 @@
         return MBEDTLS_ERR_SSL_NON_FATAL;
     }
 
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->handshake != NULL &&
+        ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER  )
+    {
+        ssl_handshake_wrapup_free_hs_transform( ssl );
+    }
+#endif
+
     return( 0 );
 }
 
@@ -6485,6 +6465,61 @@
     return( ssl->in_offt == NULL ? 0 : ssl->in_msglen );
 }
 
+int mbedtls_ssl_check_pending( const mbedtls_ssl_context *ssl )
+{
+    /*
+     * Case A: We're currently holding back
+     * a message for further processing.
+     */
+
+    if( ssl->keep_current_message == 1 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: record held back for processing" ) );
+        return( 1 );
+    }
+
+    /*
+     * Case B: Further records are pending in the current datagram.
+     */
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->in_left > ssl->next_record_offset )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: more records within current datagram" ) );
+        return( 1 );
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+    /*
+     * Case C: A handshake message is being processed.
+     */
+
+    if( ssl->in_hslen > 0 && ssl->in_hslen < ssl->in_msglen )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: more handshake messages within current record" ) );
+        return( 1 );
+    }
+
+    /*
+     * Case D: An application data message is being processed
+     */
+    if( ssl->in_offt != NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: application data record is being processed" ) );
+        return( 1 );
+    }
+
+    /*
+     * In all other cases, the rest of the message can be dropped.
+     * As in ssl_read_record_layer, this needs to be adapted if
+     * we implement support for multiple alerts in single records.
+     */
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: nothing pending" ) );
+    return( 0 );
+}
+
 uint32_t mbedtls_ssl_get_verify_result( const mbedtls_ssl_context *ssl )
 {
     if( ssl->session != NULL )
@@ -6893,25 +6928,16 @@
     }
 
     /*
-     * TODO
-     *
-     * The logic should be streamlined here:
-     *
-     * Instead of
-     *
+     * The logic could be streamlined here. Instead of
      * - Manually checking whether ssl->in_offt is NULL
      * - Fetching a new record if yes
      * - Setting ssl->in_offt if one finds an application record
      * - Resetting keep_current_message after handling the application data
-     *
      * one should
-     *
      * - Adapt read_record to set ssl->in_offt automatically
      *   when a new application data record is processed.
      * - Always call mbedtls_ssl_read_record here.
-     *
      * This way, the logic of ssl_read would be much clearer:
-     *
      * (1) Always call record layer and see what kind of record is on
      *     and have it ready for consumption (in particular, in_offt
      *     properly set for application data records).
@@ -6921,13 +6947,12 @@
      * (3) If it's something different from application data,
      *     handle it accordingly, e.g. potentially start a
      *     renegotiation.
-     *
      * This will also remove the need to manually reset
      * ssl->keep_current_message = 0 below.
-     *
      */
 
-    if( ssl->in_offt == NULL )
+    /* Loop as long as no application data record is available */
+    while( ssl->in_offt == NULL )
     {
         /* Start timer if not already running */
         if( ssl->f_get_timer != NULL &&
@@ -6981,7 +7006,9 @@
                 /* With DTLS, drop the packet (probably from last handshake) */
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
                 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
-                    return( MBEDTLS_ERR_SSL_WANT_READ );
+                {
+                    continue;
+                }
 #endif
                 return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
             }
@@ -6996,7 +7023,9 @@
                 /* With DTLS, drop the packet (probably from last handshake) */
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
                 if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
-                    return( MBEDTLS_ERR_SSL_WANT_READ );
+                {
+                    continue;
+                }
 #endif
                 return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
             }
@@ -7069,7 +7098,25 @@
                 }
             }
 
-            return( MBEDTLS_ERR_SSL_WANT_READ );
+            /* At this point, we don't know whether the renegotiation has been
+             * completed or not. The cases to consider are the following:
+             * 1) The renegotiation is complete. In this case, no new record
+             *    has been read yet.
+             * 2) The renegotiation is incomplete because the client received
+             *    an application data record while awaiting the ServerHello.
+             * 3) The renegotiation is incomplete because the client received
+             *    a non-handshake, non-application data message while awaiting
+             *    the ServerHello.
+             * In each of these case, looping will be the proper action:
+             * - For 1), the next iteration will read a new record and check
+             *   if it's application data.
+             * - For 2), the loop condition isn't satisfied as application data
+             *   is present, hence continue is the same as break
+             * - For 3), the loop condition is satisfied and read_record
+             *   will re-deliver the message that was held back by the client
+             *   when expecting the ServerHello.
+             */
+            continue;
         }
 #if defined(MBEDTLS_SSL_RENEGOTIATION)
         else if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index 8e2feb1..5d8969d 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -73,6 +73,7 @@
 #define DFL_REQUEST_SIZE        -1
 #define DFL_DEBUG_LEVEL         0
 #define DFL_NBIO                0
+#define DFL_EVENT               0
 #define DFL_READ_TIMEOUT        0
 #define DFL_MAX_RESEND          0
 #define DFL_CA_FILE             ""
@@ -245,24 +246,26 @@
     "    server_addr=%%s      default: given by name\n"     \
     "    server_port=%%d      default: 4433\n"              \
     "    request_page=%%s     default: \".\"\n"             \
-    "    request_size=%%d     default: about 34 (basic request)\n"           \
+    "    request_size=%%d     default: about 34 (basic request)\n" \
     "                        (minimum: 0, max: " MAX_REQUEST_SIZE_STR " )\n" \
-    "    debug_level=%%d      default: 0 (disabled)\n"      \
-    "    nbio=%%d             default: 0 (blocking I/O)\n"  \
-    "                        options: 1 (non-blocking), 2 (added delays)\n" \
-    "    read_timeout=%%d     default: 0 ms (no timeout)\n"    \
+    "    debug_level=%%d      default: 0 (disabled)\n"             \
+    "    nbio=%%d             default: 0 (blocking I/O)\n"         \
+    "                        options: 1 (non-blocking), 2 (added delays)\n"   \
+    "    event=%%d            default: 0 (loop)\n"                            \
+    "                        options: 1 (level-triggered, implies nbio=1),\n" \
+    "    read_timeout=%%d     default: 0 ms (no timeout)\n"        \
     "    max_resend=%%d       default: 0 (no resend on timeout)\n" \
     "\n"                                                    \
     USAGE_DTLS                                              \
     "\n"                                                    \
-    "    auth_mode=%%s        default: (library default: none)\n"      \
+    "    auth_mode=%%s        default: (library default: none)\n" \
     "                        options: none, optional, required\n" \
     USAGE_IO                                                \
     "\n"                                                    \
     USAGE_PSK                                               \
     USAGE_ECJPAKE                                           \
     "\n"                                                    \
-    "    allow_legacy=%%d     default: (library default: no)\n"      \
+    "    allow_legacy=%%d     default: (library default: no)\n"   \
     USAGE_RENEGO                                            \
     "    exchanges=%%d        default: 1\n"                 \
     "    reconnect=%%d        default: 0 (disabled)\n"      \
@@ -302,7 +305,8 @@
     const char *server_port;    /* port on which the ssl service runs       */
     int debug_level;            /* level of debugging                       */
     int nbio;                   /* should I/O be blocking?                  */
-    uint32_t read_timeout;      /* timeout on mbedtls_ssl_read() in milliseconds    */
+    int event;                  /* loop or event-driven IO? level or edge triggered? */
+    uint32_t read_timeout;      /* timeout on mbedtls_ssl_read() in milliseconds     */
     int max_resend;             /* DTLS times to resend on read timeout     */
     const char *request_page;   /* page on server to request                */
     int request_size;           /* pad request with header to requested size */
@@ -353,7 +357,8 @@
         if( *p == '/' || *p == '\\' )
             basename = p + 1;
 
-    mbedtls_fprintf( (FILE *) ctx, "%s:%04d: |%d| %s", basename, line, level, str );
+    mbedtls_fprintf( (FILE *) ctx, "%s:%04d: |%d| %s",
+                     basename, line, level, str );
     fflush(  (FILE *) ctx  );
 }
 
@@ -399,7 +404,8 @@
 /*
  * Enabled if debug_level > 1 in code below
  */
-static int my_verify( void *data, mbedtls_x509_crt *crt, int depth, uint32_t *flags )
+static int my_verify( void *data, mbedtls_x509_crt *crt,
+                      int depth, uint32_t *flags )
 {
     char buf[1024];
     ((void) data);
@@ -436,6 +442,57 @@
 };
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
+/*
+ * Wait for an event from the underlying transport or the timer
+ * (Used in event-driven IO mode).
+ */
+#if !defined(MBEDTLS_TIMING_C)
+int idle( mbedtls_net_context *fd,
+          int idle_reason )
+#else
+int idle( mbedtls_net_context *fd,
+          mbedtls_timing_delay_context *timer,
+          int idle_reason )
+#endif
+{
+
+    int ret;
+    int poll_type = 0;
+
+    if( idle_reason == MBEDTLS_ERR_SSL_WANT_WRITE )
+        poll_type = MBEDTLS_NET_POLL_WRITE;
+    else if( idle_reason == MBEDTLS_ERR_SSL_WANT_READ )
+        poll_type = MBEDTLS_NET_POLL_READ;
+#if !defined(MBEDTLS_TIMING_C)
+    else
+        return( 0 );
+#endif
+
+    while( 1 )
+    {
+        /* Check if timer has expired */
+#if defined(MBEDTLS_TIMING_C)
+        if( timer != NULL &&
+            mbedtls_timing_get_delay( timer ) == 2 )
+        {
+            break;
+        }
+#endif /* MBEDTLS_TIMING_C */
+
+        /* Check if underlying transport became available */
+        if( poll_type != 0 )
+        {
+            ret = mbedtls_net_poll( fd, poll_type, 0 );
+            if( ret < 0 )
+                return( ret );
+            if( ret == poll_type )
+                break;
+        }
+    }
+
+    return( 0 );
+}
+
 int main( int argc, char *argv[] )
 {
     int ret = 0, len, tail_len, i, written, frags, retry_left;
@@ -521,6 +578,7 @@
     opt.server_port         = DFL_SERVER_PORT;
     opt.debug_level         = DFL_DEBUG_LEVEL;
     opt.nbio                = DFL_NBIO;
+    opt.event               = DFL_EVENT;
     opt.read_timeout        = DFL_READ_TIMEOUT;
     opt.max_resend          = DFL_MAX_RESEND;
     opt.request_page        = DFL_REQUEST_PAGE;
@@ -594,6 +652,12 @@
             if( opt.nbio < 0 || opt.nbio > 2 )
                 goto usage;
         }
+        else if( strcmp( p, "event" ) == 0 )
+        {
+            opt.event = atoi( q );
+            if( opt.event < 0 || opt.event > 2 )
+                goto usage;
+        }
         else if( strcmp( p, "read_timeout" ) == 0 )
             opt.read_timeout = atoi( q );
         else if( strcmp( p, "max_resend" ) == 0 )
@@ -638,16 +702,23 @@
         }
         else if( strcmp( p, "renegotiation" ) == 0 )
         {
-            opt.renegotiation = (atoi( q )) ? MBEDTLS_SSL_RENEGOTIATION_ENABLED :
-                                              MBEDTLS_SSL_RENEGOTIATION_DISABLED;
+            opt.renegotiation = (atoi( q )) ?
+                MBEDTLS_SSL_RENEGOTIATION_ENABLED :
+                MBEDTLS_SSL_RENEGOTIATION_DISABLED;
         }
         else if( strcmp( p, "allow_legacy" ) == 0 )
         {
             switch( atoi( q ) )
             {
-                case -1: opt.allow_legacy = MBEDTLS_SSL_LEGACY_BREAK_HANDSHAKE; break;
-                case 0:  opt.allow_legacy = MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION; break;
-                case 1:  opt.allow_legacy = MBEDTLS_SSL_LEGACY_ALLOW_RENEGOTIATION; break;
+                case -1:
+                    opt.allow_legacy = MBEDTLS_SSL_LEGACY_BREAK_HANDSHAKE;
+                    break;
+                case 0:
+                    opt.allow_legacy = MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION;
+                    break;
+                case 1:
+                    opt.allow_legacy = MBEDTLS_SSL_LEGACY_ALLOW_RENEGOTIATION;
+                    break;
                 default: goto usage;
             }
         }
@@ -704,8 +775,12 @@
         {
             switch( atoi( q ) )
             {
-                case 0: opt.extended_ms = MBEDTLS_SSL_EXTENDED_MS_DISABLED; break;
-                case 1: opt.extended_ms = MBEDTLS_SSL_EXTENDED_MS_ENABLED; break;
+                case 0:
+                    opt.extended_ms = MBEDTLS_SSL_EXTENDED_MS_DISABLED;
+                    break;
+                case 1:
+                    opt.extended_ms = MBEDTLS_SSL_EXTENDED_MS_ENABLED;
+                    break;
                 default: goto usage;
             }
         }
@@ -864,6 +939,15 @@
             goto usage;
     }
 
+    /* Event-driven IO is incompatible with the above custom
+     * receive and send functions, as the polling builds on
+     * refers to the underlying net_context. */
+    if( opt.event == 1 && opt.nbio != 1 )
+    {
+        mbedtls_printf( "Warning: event-driven IO mandates nbio=1 - overwrite\n" );
+        opt.nbio = 1;
+    }
+
 #if defined(MBEDTLS_DEBUG_C)
     mbedtls_debug_set_threshold( opt.debug_level );
 #endif
@@ -871,19 +955,20 @@
     if( opt.force_ciphersuite[0] > 0 )
     {
         const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
-        ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( opt.force_ciphersuite[0] );
+        ciphersuite_info =
+            mbedtls_ssl_ciphersuite_from_id( opt.force_ciphersuite[0] );
 
         if( opt.max_version != -1 &&
             ciphersuite_info->min_minor_ver > opt.max_version )
         {
-            mbedtls_printf("forced ciphersuite not allowed with this protocol version\n");
+            mbedtls_printf( "forced ciphersuite not allowed with this protocol version\n" );
             ret = 2;
             goto usage;
         }
         if( opt.min_version != -1 &&
             ciphersuite_info->max_minor_ver < opt.min_version )
         {
-            mbedtls_printf("forced ciphersuite not allowed with this protocol version\n");
+            mbedtls_printf( "forced ciphersuite not allowed with this protocol version\n" );
             ret = 2;
             goto usage;
         }
@@ -909,7 +994,7 @@
         {
             if( opt.arc4 == MBEDTLS_SSL_ARC4_DISABLED )
             {
-                mbedtls_printf("forced RC4 ciphersuite with RC4 disabled\n");
+                mbedtls_printf( "forced RC4 ciphersuite with RC4 disabled\n" );
                 ret = 2;
                 goto usage;
             }
@@ -929,7 +1014,7 @@
 
         if( strlen( opt.psk ) % 2 != 0 )
         {
-            mbedtls_printf("pre-shared key not valid hex\n");
+            mbedtls_printf( "pre-shared key not valid hex\n" );
             goto exit;
         }
 
@@ -946,7 +1031,7 @@
                 c -= 'A' - 10;
             else
             {
-                mbedtls_printf("pre-shared key not valid hex\n");
+                mbedtls_printf( "pre-shared key not valid hex\n" );
                 goto exit;
             }
             psk[ j / 2 ] = c << 4;
@@ -960,7 +1045,7 @@
                 c -= 'A' - 10;
             else
             {
-                mbedtls_printf("pre-shared key not valid hex\n");
+                mbedtls_printf( "pre-shared key not valid hex\n" );
                 goto exit;
             }
             psk[ j / 2 ] |= c;
@@ -1051,11 +1136,12 @@
     fflush( stdout );
 
     mbedtls_entropy_init( &entropy );
-    if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
-                               (const unsigned char *) pers,
-                               strlen( pers ) ) ) != 0 )
+    if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func,
+                                       &entropy, (const unsigned char *) pers,
+                                       strlen( pers ) ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned -0x%x\n", -ret );
+        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned -0x%x\n",
+                        -ret );
         goto exit;
     }
 
@@ -1093,12 +1179,13 @@
 #else
     {
         ret = 1;
-        mbedtls_printf("MBEDTLS_CERTS_C not defined.");
+        mbedtls_printf( "MBEDTLS_CERTS_C not defined." );
     }
 #endif
     if( ret < 0 )
     {
-        mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned -0x%x\n\n", -ret );
+        mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned -0x%x\n\n",
+                        -ret );
         goto exit;
     }
 
@@ -1121,7 +1208,8 @@
     else
 #endif
 #if defined(MBEDTLS_CERTS_C)
-        ret = mbedtls_x509_crt_parse( &clicert, (const unsigned char *) mbedtls_test_cli_crt,
+        ret = mbedtls_x509_crt_parse( &clicert,
+                (const unsigned char *) mbedtls_test_cli_crt,
                 mbedtls_test_cli_crt_len );
 #else
     {
@@ -1131,7 +1219,8 @@
 #endif
     if( ret != 0 )
     {
-        mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned -0x%x\n\n", -ret );
+        mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned -0x%x\n\n",
+                        -ret );
         goto exit;
     }
 
@@ -1144,7 +1233,8 @@
     else
 #endif
 #if defined(MBEDTLS_CERTS_C)
-        ret = mbedtls_pk_parse_key( &pkey, (const unsigned char *) mbedtls_test_cli_key,
+        ret = mbedtls_pk_parse_key( &pkey,
+                (const unsigned char *) mbedtls_test_cli_key,
                 mbedtls_test_cli_key_len, NULL, 0 );
 #else
     {
@@ -1154,7 +1244,8 @@
 #endif
     if( ret != 0 )
     {
-        mbedtls_printf( " failed\n  !  mbedtls_pk_parse_key returned -0x%x\n\n", -ret );
+        mbedtls_printf( " failed\n  !  mbedtls_pk_parse_key returned -0x%x\n\n",
+                        -ret );
         goto exit;
     }
 
@@ -1172,11 +1263,13 @@
             opt.server_addr, opt.server_port );
     fflush( stdout );
 
-    if( ( ret = mbedtls_net_connect( &server_fd, opt.server_addr, opt.server_port,
-                             opt.transport == MBEDTLS_SSL_TRANSPORT_STREAM ?
-                             MBEDTLS_NET_PROTO_TCP : MBEDTLS_NET_PROTO_UDP ) ) != 0 )
+    if( ( ret = mbedtls_net_connect( &server_fd,
+                       opt.server_addr, opt.server_port,
+                       opt.transport == MBEDTLS_SSL_TRANSPORT_STREAM ?
+                       MBEDTLS_NET_PROTO_TCP : MBEDTLS_NET_PROTO_UDP ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_net_connect returned -0x%x\n\n", -ret );
+        mbedtls_printf( " failed\n  ! mbedtls_net_connect returned -0x%x\n\n",
+                        -ret );
         goto exit;
     }
 
@@ -1186,7 +1279,8 @@
         ret = mbedtls_net_set_block( &server_fd );
     if( ret != 0 )
     {
-        mbedtls_printf( " failed\n  ! net_set_(non)block() returned -0x%x\n\n", -ret );
+        mbedtls_printf( " failed\n  ! net_set_(non)block() returned -0x%x\n\n",
+                        -ret );
         goto exit;
     }
 
@@ -1203,7 +1297,8 @@
                     opt.transport,
                     MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ssl_config_defaults returned -0x%x\n\n", -ret );
+        mbedtls_printf( " failed\n  ! mbedtls_ssl_config_defaults returned -0x%x\n\n",
+                        -ret );
         goto exit;
     }
 
@@ -1226,13 +1321,15 @@
 
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
     if( opt.hs_to_min != DFL_HS_TO_MIN || opt.hs_to_max != DFL_HS_TO_MAX )
-        mbedtls_ssl_conf_handshake_timeout( &conf, opt.hs_to_min, opt.hs_to_max );
+        mbedtls_ssl_conf_handshake_timeout( &conf, opt.hs_to_min,
+                                            opt.hs_to_max );
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
 #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
     if( ( ret = mbedtls_ssl_conf_max_frag_len( &conf, opt.mfl_code ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_max_frag_len returned %d\n\n", ret );
+        mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_max_frag_len returned %d\n\n",
+                        ret );
         goto exit;
     }
 #endif
@@ -1255,8 +1352,8 @@
 #if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
     if( opt.recsplit != DFL_RECSPLIT )
         mbedtls_ssl_conf_cbc_record_splitting( &conf, opt.recsplit
-                                    ? MBEDTLS_SSL_CBC_RECORD_SPLITTING_ENABLED
-                                    : MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED );
+                                  ? MBEDTLS_SSL_CBC_RECORD_SPLITTING_ENABLED
+                                  : MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED );
 #endif
 
 #if defined(MBEDTLS_DHM_C)
@@ -1268,7 +1365,8 @@
     if( opt.alpn_string != NULL )
         if( ( ret = mbedtls_ssl_conf_alpn_protocols( &conf, alpn_list ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_alpn_protocols returned %d\n\n", ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_alpn_protocols returned %d\n\n",
+                            ret );
             goto exit;
         }
 #endif
@@ -1307,7 +1405,8 @@
     {
         if( ( ret = mbedtls_ssl_conf_own_cert( &conf, &clicert, &pkey ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_own_cert returned %d\n\n", ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_own_cert returned %d\n\n",
+                            ret );
             goto exit;
         }
     }
@@ -1326,16 +1425,19 @@
                              (const unsigned char *) opt.psk_identity,
                              strlen( opt.psk_identity ) ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_psk returned %d\n\n", ret );
+        mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_psk returned %d\n\n",
+                        ret );
         goto exit;
     }
 #endif
 
     if( opt.min_version != DFL_MIN_VERSION )
-        mbedtls_ssl_conf_min_version( &conf, MBEDTLS_SSL_MAJOR_VERSION_3, opt.min_version );
+        mbedtls_ssl_conf_min_version( &conf, MBEDTLS_SSL_MAJOR_VERSION_3,
+                                      opt.min_version );
 
     if( opt.max_version != DFL_MAX_VERSION )
-        mbedtls_ssl_conf_max_version( &conf, MBEDTLS_SSL_MAJOR_VERSION_3, opt.max_version );
+        mbedtls_ssl_conf_max_version( &conf, MBEDTLS_SSL_MAJOR_VERSION_3,
+                                      opt.max_version );
 
 #if defined(MBEDTLS_SSL_FALLBACK_SCSV)
     if( opt.fallback != DFL_FALLBACK )
@@ -1344,14 +1446,16 @@
 
     if( ( ret = mbedtls_ssl_setup( &ssl, &conf ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ssl_setup returned -0x%x\n\n", -ret );
+        mbedtls_printf( " failed\n  ! mbedtls_ssl_setup returned -0x%x\n\n",
+                        -ret );
         goto exit;
     }
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
     if( ( ret = mbedtls_ssl_set_hostname( &ssl, opt.server_name ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n", ret );
+        mbedtls_printf( " failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n",
+                        ret );
         goto exit;
     }
 #endif
@@ -1363,7 +1467,8 @@
                         (const unsigned char *) opt.ecjpake_pw,
                                         strlen( opt.ecjpake_pw ) ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_set_hs_ecjpake_password returned %d\n\n", ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_set_hs_ecjpake_password returned %d\n\n",
+                            ret );
             goto exit;
         }
     }
@@ -1372,7 +1477,8 @@
     if( opt.nbio == 2 )
         mbedtls_ssl_set_bio( &ssl, &server_fd, my_send, my_recv, NULL );
     else
-        mbedtls_ssl_set_bio( &ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv,
+        mbedtls_ssl_set_bio( &ssl, &server_fd,
+                             mbedtls_net_send, mbedtls_net_recv,
                              opt.nbio == 0 ? mbedtls_net_recv_timeout : NULL );
 
 #if defined(MBEDTLS_TIMING_C)
@@ -1390,9 +1496,11 @@
 
     while( ( ret = mbedtls_ssl_handshake( &ssl ) ) != 0 )
     {
-        if( ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+        if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
+            ret != MBEDTLS_ERR_SSL_WANT_WRITE )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_handshake returned -0x%x\n", -ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_handshake returned -0x%x\n",
+                            -ret );
             if( ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED )
                 mbedtls_printf(
                     "    Unable to verify the server's certificate. "
@@ -1404,10 +1512,23 @@
             mbedtls_printf( "\n" );
             goto exit;
         }
+
+        /* For event-driven IO, wait for socket to become available */
+        if( opt.event == 1 /* level triggered IO */ )
+        {
+#if defined(MBEDTLS_TIMING_C)
+            ret = idle( &server_fd, &timer, ret );
+#else
+            ret = idle( &server_fd, ret );
+#endif
+            if( ret != 0 )
+                goto exit;
+        }
     }
 
     mbedtls_printf( " ok\n    [ Protocol is %s ]\n    [ Ciphersuite is %s ]\n",
-            mbedtls_ssl_get_version( &ssl ), mbedtls_ssl_get_ciphersuite( &ssl ) );
+                    mbedtls_ssl_get_version( &ssl ),
+                    mbedtls_ssl_get_ciphersuite( &ssl ) );
 
     if( ( ret = mbedtls_ssl_get_record_expansion( &ssl ) ) >= 0 )
         mbedtls_printf( "    [ Record expansion is %d ]\n", ret );
@@ -1435,7 +1556,8 @@
 
         if( ( ret = mbedtls_ssl_get_session( &ssl, &saved_session ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_get_session returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_get_session returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
 
@@ -1454,7 +1576,8 @@
 
         mbedtls_printf( " failed\n" );
 
-        mbedtls_x509_crt_verify_info( vrfy_buf, sizeof( vrfy_buf ), "  ! ", flags );
+        mbedtls_x509_crt_verify_info( vrfy_buf, sizeof( vrfy_buf ),
+                                      "  ! ", flags );
 
         mbedtls_printf( "%s\n", vrfy_buf );
     }
@@ -1484,9 +1607,21 @@
             if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
                 ret != MBEDTLS_ERR_SSL_WANT_WRITE )
             {
-                mbedtls_printf( " failed\n  ! mbedtls_ssl_renegotiate returned %d\n\n", ret );
+                mbedtls_printf( " failed\n  ! mbedtls_ssl_renegotiate returned %d\n\n",
+                                ret );
                 goto exit;
             }
+
+            /* For event-driven IO, wait for socket to become available */
+            if( opt.event == 1 /* level triggered IO */ )
+            {
+#if defined(MBEDTLS_TIMING_C)
+                idle( &server_fd, &timer, ret );
+#else
+                idle( &server_fd, ret );
+#endif
+            }
+
         }
         mbedtls_printf( " ok\n" );
     }
@@ -1530,27 +1665,54 @@
     {
         for( written = 0, frags = 0; written < len; written += ret, frags++ )
         {
-            while( ( ret = mbedtls_ssl_write( &ssl, buf + written, len - written ) )
-                           <= 0 )
+            while( ( ret = mbedtls_ssl_write( &ssl, buf + written,
+                                              len - written ) ) <= 0 )
             {
                 if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
                     ret != MBEDTLS_ERR_SSL_WANT_WRITE )
                 {
-                    mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned -0x%x\n\n", -ret );
+                    mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned -0x%x\n\n",
+                                    -ret );
                     goto exit;
                 }
+
+                /* For event-driven IO, wait for socket to become available */
+                if( opt.event == 1 /* level triggered IO */ )
+                {
+#if defined(MBEDTLS_TIMING_C)
+                    idle( &server_fd, &timer, ret );
+#else
+                    idle( &server_fd, ret );
+#endif
+                }
             }
         }
     }
     else /* Not stream, so datagram */
     {
-        do ret = mbedtls_ssl_write( &ssl, buf, len );
-        while( ret == MBEDTLS_ERR_SSL_WANT_READ ||
-               ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+        while( 1 )
+        {
+            ret = mbedtls_ssl_write( &ssl, buf, len );
+
+            if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
+                ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+                break;
+
+            /* For event-driven IO, wait for socket to become available */
+            if( opt.event == 1 /* level triggered IO */ )
+            {
+#if defined(MBEDTLS_TIMING_C)
+                idle( &server_fd, &timer, ret );
+#else
+                idle( &server_fd, ret );
+#endif
+            }
+        }
 
         if( ret < 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned %d\n\n", ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned %d\n\n",
+                            ret );
             goto exit;
         }
 
@@ -1565,7 +1727,8 @@
     }
 
     buf[written] = '\0';
-    mbedtls_printf( " %d bytes written in %d fragments\n\n%s\n", written, frags, (char *) buf );
+    mbedtls_printf( " %d bytes written in %d fragments\n\n%s\n",
+                    written, frags, (char *) buf );
 
     /*
      * 7. Read the HTTP response
@@ -1586,7 +1749,18 @@
 
             if( ret == MBEDTLS_ERR_SSL_WANT_READ ||
                 ret == MBEDTLS_ERR_SSL_WANT_WRITE )
+            {
+                /* For event-driven IO, wait for socket to become available */
+                if( opt.event == 1 /* level triggered IO */ )
+                {
+#if defined(MBEDTLS_TIMING_C)
+                    idle( &server_fd, &timer, ret );
+#else
+                    idle( &server_fd, ret );
+#endif
+                }
                 continue;
+            }
 
             if( ret <= 0 )
             {
@@ -1604,7 +1778,8 @@
                         goto reconnect;
 
                     default:
-                        mbedtls_printf( " mbedtls_ssl_read returned -0x%x\n", -ret );
+                        mbedtls_printf( " mbedtls_ssl_read returned -0x%x\n",
+                                        -ret );
                         goto exit;
                 }
             }
@@ -1628,9 +1803,24 @@
         len = sizeof( buf ) - 1;
         memset( buf, 0, sizeof( buf ) );
 
-        do ret = mbedtls_ssl_read( &ssl, buf, len );
-        while( ret == MBEDTLS_ERR_SSL_WANT_READ ||
-               ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+        while( 1 )
+        {
+            ret = mbedtls_ssl_read( &ssl, buf, len );
+
+            if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
+                ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+                break;
+
+            /* For event-driven IO, wait for socket to become available */
+            if( opt.event == 1 /* level triggered IO */ )
+            {
+#if defined(MBEDTLS_TIMING_C)
+                idle( &server_fd, &timer, ret );
+#else
+                idle( &server_fd, ret );
+#endif
+            }
+        }
 
         if( ret <= 0 )
         {
@@ -1671,7 +1861,8 @@
 
         if( ( ret = mbedtls_ssl_session_reset( &ssl ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_session_reset returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_session_reset returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
 
@@ -1680,9 +1871,20 @@
             if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
                 ret != MBEDTLS_ERR_SSL_WANT_WRITE )
             {
-                mbedtls_printf( " failed\n  ! mbedtls_ssl_handshake returned -0x%x\n\n", -ret );
+                mbedtls_printf( " failed\n  ! mbedtls_ssl_handshake returned -0x%x\n\n",
+                                -ret );
                 goto exit;
             }
+
+            /* For event-driven IO, wait for socket to become available */
+            if( opt.event == 1 /* level triggered IO */ )
+            {
+#if defined(MBEDTLS_TIMING_C)
+                idle( &server_fd, &timer, ret );
+#else
+                idle( &server_fd, ret );
+#endif
+            }
         }
 
         mbedtls_printf( " ok\n" );
@@ -1729,21 +1931,25 @@
 
         if( ( ret = mbedtls_ssl_session_reset( &ssl ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_session_reset returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_session_reset returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
 
         if( ( ret = mbedtls_ssl_set_session( &ssl, &saved_session ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_session returned %d\n\n", ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_conf_session returned %d\n\n",
+                            ret );
             goto exit;
         }
 
-        if( ( ret = mbedtls_net_connect( &server_fd, opt.server_addr, opt.server_port,
-                                 opt.transport == MBEDTLS_SSL_TRANSPORT_STREAM ?
-                                 MBEDTLS_NET_PROTO_TCP : MBEDTLS_NET_PROTO_UDP ) ) != 0 )
+        if( ( ret = mbedtls_net_connect( &server_fd,
+                        opt.server_addr, opt.server_port,
+                        opt.transport == MBEDTLS_SSL_TRANSPORT_STREAM ?
+                        MBEDTLS_NET_PROTO_TCP : MBEDTLS_NET_PROTO_UDP ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! mbedtls_net_connect returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  ! mbedtls_net_connect returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
 
@@ -1754,7 +1960,7 @@
         if( ret != 0 )
         {
             mbedtls_printf( " failed\n  ! net_set_(non)block() returned -0x%x\n\n",
-                    -ret );
+                            -ret );
             goto exit;
         }
 
@@ -1763,7 +1969,8 @@
             if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
                 ret != MBEDTLS_ERR_SSL_WANT_WRITE )
             {
-                mbedtls_printf( " failed\n  ! mbedtls_ssl_handshake returned -0x%x\n\n", -ret );
+                mbedtls_printf( " failed\n  ! mbedtls_ssl_handshake returned -0x%x\n\n",
+                                -ret );
                 goto exit;
             }
         }
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index cc29b49..6bfb210 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -101,6 +101,7 @@
 #define DFL_SERVER_PORT         "4433"
 #define DFL_DEBUG_LEVEL         0
 #define DFL_NBIO                0
+#define DFL_EVENT               0
 #define DFL_READ_TIMEOUT        0
 #define DFL_CA_FILE             ""
 #define DFL_CA_PATH             ""
@@ -331,6 +332,8 @@
     "    debug_level=%%d      default: 0 (disabled)\n"      \
     "    nbio=%%d             default: 0 (blocking I/O)\n"  \
     "                        options: 1 (non-blocking), 2 (added delays)\n" \
+    "    event=%%d            default: 0 (loop)\n"                            \
+    "                        options: 1 (level-triggered, implies nbio=1),\n" \
     "    read_timeout=%%d     default: 0 ms (no timeout)\n"    \
     "\n"                                                    \
     USAGE_DTLS                                              \
@@ -399,6 +402,7 @@
     const char *server_port;    /* port on which the ssl service runs       */
     int debug_level;            /* level of debugging                       */
     int nbio;                   /* should I/O be blocking?                  */
+    int event;                  /* loop or event-driven IO? level or edge triggered? */
     uint32_t read_timeout;      /* timeout on mbedtls_ssl_read() in milliseconds    */
     const char *ca_file;        /* the file with the CA certificate(s)      */
     const char *ca_path;        /* the path with the CA certificate(s) reside */
@@ -837,6 +841,56 @@
 };
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
+/*
+ * Wait for an event from the underlying transport or the timer
+ * (Used in event-driven IO mode).
+ */
+#if !defined(MBEDTLS_TIMING_C)
+int idle( mbedtls_net_context *fd,
+          int idle_reason )
+#else
+int idle( mbedtls_net_context *fd,
+          mbedtls_timing_delay_context *timer,
+          int idle_reason )
+#endif
+{
+    int ret;
+    int poll_type = 0;
+
+    if( idle_reason == MBEDTLS_ERR_SSL_WANT_WRITE )
+        poll_type = MBEDTLS_NET_POLL_WRITE;
+    else if( idle_reason == MBEDTLS_ERR_SSL_WANT_READ )
+        poll_type = MBEDTLS_NET_POLL_READ;
+#if !defined(MBEDTLS_TIMING_C)
+    else
+        return( 0 );
+#endif
+
+    while( 1 )
+    {
+        /* Check if timer has expired */
+#if defined(MBEDTLS_TIMING_C)
+        if( timer != NULL &&
+            mbedtls_timing_get_delay( timer ) == 2 )
+        {
+            break;
+        }
+#endif /* MBEDTLS_TIMING_C */
+
+        /* Check if underlying transport became available */
+        if( poll_type != 0 )
+        {
+            ret = mbedtls_net_poll( fd, poll_type, 0 );
+            if( ret < 0 )
+                return( ret );
+            if( ret == poll_type )
+                break;
+        }
+    }
+
+    return( 0 );
+}
+
 int main( int argc, char *argv[] )
 {
     int ret = 0, len, written, frags, exchanges_left;
@@ -969,6 +1023,7 @@
     opt.server_addr         = DFL_SERVER_ADDR;
     opt.server_port         = DFL_SERVER_PORT;
     opt.debug_level         = DFL_DEBUG_LEVEL;
+    opt.event               = DFL_EVENT;
     opt.nbio                = DFL_NBIO;
     opt.read_timeout        = DFL_READ_TIMEOUT;
     opt.ca_file             = DFL_CA_FILE;
@@ -1047,6 +1102,12 @@
             if( opt.nbio < 0 || opt.nbio > 2 )
                 goto usage;
         }
+        else if( strcmp( p, "event" ) == 0 )
+        {
+            opt.event = atoi( q );
+            if( opt.event < 0 || opt.event > 2 )
+                goto usage;
+        }
         else if( strcmp( p, "read_timeout" ) == 0 )
             opt.read_timeout = atoi( q );
         else if( strcmp( p, "ca_file" ) == 0 )
@@ -1088,16 +1149,23 @@
             opt.version_suites = q;
         else if( strcmp( p, "renegotiation" ) == 0 )
         {
-            opt.renegotiation = (atoi( q )) ? MBEDTLS_SSL_RENEGOTIATION_ENABLED :
-                                              MBEDTLS_SSL_RENEGOTIATION_DISABLED;
+            opt.renegotiation = (atoi( q )) ?
+                MBEDTLS_SSL_RENEGOTIATION_ENABLED :
+                MBEDTLS_SSL_RENEGOTIATION_DISABLED;
         }
         else if( strcmp( p, "allow_legacy" ) == 0 )
         {
             switch( atoi( q ) )
             {
-                case -1: opt.allow_legacy = MBEDTLS_SSL_LEGACY_BREAK_HANDSHAKE; break;
-                case 0:  opt.allow_legacy = MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION; break;
-                case 1:  opt.allow_legacy = MBEDTLS_SSL_LEGACY_ALLOW_RENEGOTIATION; break;
+                case -1:
+                    opt.allow_legacy = MBEDTLS_SSL_LEGACY_BREAK_HANDSHAKE;
+                    break;
+                case 0:
+                    opt.allow_legacy = MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION;
+                    break;
+                case 1:
+                    opt.allow_legacy = MBEDTLS_SSL_LEGACY_ALLOW_RENEGOTIATION;
+                    break;
                 default: goto usage;
             }
         }
@@ -1254,8 +1322,12 @@
         {
             switch( atoi( q ) )
             {
-                case 0: opt.extended_ms = MBEDTLS_SSL_EXTENDED_MS_DISABLED; break;
-                case 1: opt.extended_ms = MBEDTLS_SSL_EXTENDED_MS_ENABLED; break;
+                case 0:
+                    opt.extended_ms = MBEDTLS_SSL_EXTENDED_MS_DISABLED;
+                    break;
+                case 1:
+                    opt.extended_ms = MBEDTLS_SSL_EXTENDED_MS_ENABLED;
+                    break;
                 default: goto usage;
             }
         }
@@ -1328,6 +1400,15 @@
             goto usage;
     }
 
+    /* Event-driven IO is incompatible with the above custom
+     * receive and send functions, as the polling builds on
+     * refers to the underlying net_context. */
+    if( opt.event == 1 && opt.nbio != 1 )
+    {
+        mbedtls_printf( "Warning: event-driven IO mandates nbio=1 - overwrite\n" );
+        opt.nbio = 1;
+    }
+
 #if defined(MBEDTLS_DEBUG_C)
     mbedtls_debug_set_threshold( opt.debug_level );
 #endif
@@ -1335,19 +1416,20 @@
     if( opt.force_ciphersuite[0] > 0 )
     {
         const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
-        ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( opt.force_ciphersuite[0] );
+        ciphersuite_info =
+            mbedtls_ssl_ciphersuite_from_id( opt.force_ciphersuite[0] );
 
         if( opt.max_version != -1 &&
             ciphersuite_info->min_minor_ver > opt.max_version )
         {
-            mbedtls_printf("forced ciphersuite not allowed with this protocol version\n");
+            mbedtls_printf( "forced ciphersuite not allowed with this protocol version\n" );
             ret = 2;
             goto usage;
         }
         if( opt.min_version != -1 &&
             ciphersuite_info->max_minor_ver < opt.min_version )
         {
-            mbedtls_printf("forced ciphersuite not allowed with this protocol version\n");
+            mbedtls_printf( "forced ciphersuite not allowed with this protocol version\n" );
             ret = 2;
             goto usage;
         }
@@ -1526,11 +1608,12 @@
     fflush( stdout );
 
     mbedtls_entropy_init( &entropy );
-    if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
-                               (const unsigned char *) pers,
-                               strlen( pers ) ) ) != 0 )
+    if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func,
+                                       &entropy, (const unsigned char *) pers,
+                                       strlen( pers ) ) ) != 0 )
     {
-        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned -0x%x\n", -ret );
+        mbedtls_printf( " failed\n  ! mbedtls_ctr_drbg_seed returned -0x%x\n",
+                        -ret );
         goto exit;
     }
 
@@ -1627,7 +1710,7 @@
         if( ( ret = mbedtls_pk_parse_keyfile( &pkey2, opt.key_file2, "" ) ) != 0 )
         {
             mbedtls_printf( " failed\n  !  mbedtls_pk_parse_keyfile(2) returned -0x%x\n\n",
-                    -ret );
+                            -ret );
             goto exit;
         }
     }
@@ -1645,8 +1728,7 @@
         strcmp( opt.key_file2, "none" ) != 0 )
     {
 #if !defined(MBEDTLS_CERTS_C)
-        mbedtls_printf( "Not certificated or key provided, and \n"
-                "MBEDTLS_CERTS_C not defined!\n" );
+        mbedtls_printf( "Not certificated or key provided, and \nMBEDTLS_CERTS_C not defined!\n" );
         goto exit;
 #else
 #if defined(MBEDTLS_RSA_C)
@@ -1654,14 +1736,16 @@
                                     (const unsigned char *) mbedtls_test_srv_crt_rsa,
                                     mbedtls_test_srv_crt_rsa_len ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  !  mbedtls_x509_crt_parse returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
         if( ( ret = mbedtls_pk_parse_key( &pkey,
                                   (const unsigned char *) mbedtls_test_srv_key_rsa,
                                   mbedtls_test_srv_key_rsa_len, NULL, 0 ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  !  mbedtls_pk_parse_key returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  !  mbedtls_pk_parse_key returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
         key_cert_init = 2;
@@ -1671,14 +1755,16 @@
                                     (const unsigned char *) mbedtls_test_srv_crt_ec,
                                     mbedtls_test_srv_crt_ec_len ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  !  x509_crt_parse2 returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  !  x509_crt_parse2 returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
         if( ( ret = mbedtls_pk_parse_key( &pkey2,
                                   (const unsigned char *) mbedtls_test_srv_key_ec,
                                   mbedtls_test_srv_key_ec_len, NULL, 0 ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  !  pk_parse_key2 returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  !  pk_parse_key2 returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
         key_cert_init2 = 2;
@@ -2088,8 +2174,8 @@
         if( ( ret = mbedtls_ssl_set_client_transport_id( &ssl,
                         client_ip, cliip_len ) ) != 0 )
         {
-            mbedtls_printf( " failed\n  ! "
-                    "mbedtls_ssl_set_client_transport_id() returned -0x%x\n\n", -ret );
+            mbedtls_printf( " failed\n  ! mbedtls_ssl_set_client_transport_id() returned -0x%x\n\n",
+                            -ret );
             goto exit;
         }
     }
@@ -2117,9 +2203,24 @@
     mbedtls_printf( "  . Performing the SSL/TLS handshake..." );
     fflush( stdout );
 
-    do ret = mbedtls_ssl_handshake( &ssl );
-    while( ret == MBEDTLS_ERR_SSL_WANT_READ ||
-           ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+    while( ( ret = mbedtls_ssl_handshake( &ssl ) ) != 0 )
+    {
+        if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
+            ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+            break;
+
+        /* For event-driven IO, wait for socket to become available */
+        if( opt.event == 1 /* level triggered IO */ )
+        {
+#if defined(MBEDTLS_TIMING_C)
+            ret = idle( &client_fd, &timer, ret );
+#else
+            ret = idle( &client_fd, ret );
+#endif
+            if( ret != 0 )
+                goto reset;
+        }
+    }
 
     if( ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED )
     {
@@ -2225,7 +2326,18 @@
 
             if( ret == MBEDTLS_ERR_SSL_WANT_READ ||
                 ret == MBEDTLS_ERR_SSL_WANT_WRITE )
+            {
+                if( opt.event == 1 /* level triggered IO */ )
+                {
+#if defined(MBEDTLS_TIMING_C)
+                    idle( &client_fd, &timer, ret );
+#else
+                    idle( &client_fd, ret );
+#endif
+                }
+
                 continue;
+            }
 
             if( ret <= 0 )
             {
@@ -2313,9 +2425,40 @@
         len = sizeof( buf ) - 1;
         memset( buf, 0, sizeof( buf ) );
 
-        do ret = mbedtls_ssl_read( &ssl, buf, len );
-        while( ret == MBEDTLS_ERR_SSL_WANT_READ ||
-               ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+        while( 1 )
+        {
+            /* Without the call to `mbedtls_ssl_check_pending`, it might
+             * happen that the client sends application data in the same
+             * datagram as the Finished message concluding the handshake.
+             * In this case, the application data would be ready to be
+             * processed while the underlying transport wouldn't signal
+             * any further incoming data.
+             *
+             * See the test 'Event-driven I/O: session-id resume, UDP packing'
+             * in tests/ssl-opt.sh.
+             */
+
+            /* For event-driven IO, wait for socket to become available */
+            if( mbedtls_ssl_check_pending( &ssl ) == 0 &&
+                opt.event == 1 /* level triggered IO */ )
+            {
+#if defined(MBEDTLS_TIMING_C)
+                idle( &client_fd, &timer, MBEDTLS_ERR_SSL_WANT_READ );
+#else
+                idle( &client_fd, MBEDTLS_ERR_SSL_WANT_READ );
+#endif
+            }
+
+            ret = mbedtls_ssl_read( &ssl, buf, len );
+
+            /* Note that even if `mbedtls_ssl_check_pending` returns true,
+             * it can happen that the subsequent call to `mbedtls_ssl_read`
+             * returns `MBEDTLS_ERR_SSL_WANT_READ`, because the pending messages
+             * might be discarded (e.g. because they are retransmissions). */
+            if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
+                ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+                break;
+        }
 
         if( ret <= 0 )
         {
@@ -2356,6 +2499,16 @@
                 mbedtls_printf( " failed\n  ! mbedtls_ssl_renegotiate returned %d\n\n", ret );
                 goto reset;
             }
+
+            /* For event-driven IO, wait for socket to become available */
+            if( opt.event == 1 /* level triggered IO */ )
+            {
+#if defined(MBEDTLS_TIMING_C)
+                idle( &client_fd, &timer, ret );
+#else
+                idle( &client_fd, ret );
+#endif
+            }
         }
 
         mbedtls_printf( " ok\n" );
@@ -2390,14 +2543,39 @@
                     mbedtls_printf( " failed\n  ! mbedtls_ssl_write returned %d\n\n", ret );
                     goto reset;
                 }
+
+                /* For event-driven IO, wait for socket to become available */
+                if( opt.event == 1 /* level triggered IO */ )
+                {
+#if defined(MBEDTLS_TIMING_C)
+                    idle( &client_fd, &timer, ret );
+#else
+                    idle( &client_fd, ret );
+#endif
+                }
             }
         }
     }
     else /* Not stream, so datagram */
     {
-        do ret = mbedtls_ssl_write( &ssl, buf, len );
-        while( ret == MBEDTLS_ERR_SSL_WANT_READ ||
-               ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+        while( 1 )
+        {
+            ret = mbedtls_ssl_write( &ssl, buf, len );
+
+            if( ret != MBEDTLS_ERR_SSL_WANT_READ &&
+                ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+                break;
+
+            /* For event-driven IO, wait for socket to become available */
+            if( opt.event == 1 /* level triggered IO */ )
+            {
+#if defined(MBEDTLS_TIMING_C)
+                idle( &client_fd, &timer, ret );
+#else
+                idle( &client_fd, ret );
+#endif
+            }
+        }
 
         if( ret < 0 )
         {
diff --git a/programs/test/udp_proxy.c b/programs/test/udp_proxy.c
index 20624d2..5797f3d 100644
--- a/programs/test/udp_proxy.c
+++ b/programs/test/udp_proxy.c
@@ -53,6 +53,7 @@
 #include "mbedtls/net_sockets.h"
 #include "mbedtls/error.h"
 #include "mbedtls/ssl.h"
+#include "mbedtls/timing.h"
 
 #include <string.h>
 
@@ -74,17 +75,21 @@
 #include <unistd.h>
 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
 
-/* For gettimeofday() */
-#if !defined(_WIN32)
-#include <sys/time.h>
-#endif
-
 #define MAX_MSG_SIZE            16384 + 2048 /* max record/datagram size */
 
 #define DFL_SERVER_ADDR         "localhost"
 #define DFL_SERVER_PORT         "4433"
 #define DFL_LISTEN_ADDR         "localhost"
 #define DFL_LISTEN_PORT         "5556"
+#define DFL_PACK                0
+
+#if defined(MBEDTLS_TIMING_C)
+#define USAGE_PACK                                                          \
+    "    pack=%%d             default: 0     (don't pack)\n"                \
+    "                         options: t > 0 (pack for t milliseconds)\n"
+#else
+#define USAGE_PACK
+#endif
 
 #define USAGE                                                               \
     "\n usage: udp_proxy param=<>...\n"                                     \
@@ -105,9 +110,10 @@
     "                        drop packets larger than N bytes\n"            \
     "    bad_ad=0/1          default: 0 (don't add bad ApplicationData)\n"  \
     "    protect_hvr=0/1     default: 0 (don't protect HelloVerifyRequest)\n" \
-    "    protect_len=%%d     default: (don't protect packets of this size)\n" \
+    "    protect_len=%%d      default: (don't protect packets of this size)\n" \
     "\n"                                                                    \
     "    seed=%%d             default: (use current time)\n"                \
+    USAGE_PACK                                                              \
     "\n"
 
 /*
@@ -128,7 +134,8 @@
     int bad_ad;                 /* inject corrupted ApplicationData record  */
     int protect_hvr;            /* never drop or delay HelloVerifyRequest   */
     int protect_len;            /* never drop/delay packet of the given size*/
-
+    unsigned pack;              /* merge packets into single datagram for
+                                 * at most \c merge milliseconds if > 0     */
     unsigned int seed;          /* seed for "random" events                 */
 } opt;
 
@@ -152,6 +159,7 @@
     opt.server_port    = DFL_SERVER_PORT;
     opt.listen_addr    = DFL_LISTEN_ADDR;
     opt.listen_port    = DFL_LISTEN_PORT;
+    opt.pack           = DFL_PACK;
     /* Other members default to 0 */
 
     for( i = 1; i < argc; i++ )
@@ -193,6 +201,15 @@
             if( opt.drop < 0 || opt.drop > 20 || opt.drop == 1 )
                 exit_usage( p, q );
         }
+        else if( strcmp( p, "pack" ) == 0 )
+        {
+#if defined(MBEDTLS_TIMING_C)
+            opt.pack = (unsigned) atoi( q );
+#else
+            mbedtls_printf( " option pack only defined if MBEDTLS_TIMING_C is enabled\n" );
+            exit( 1 );
+#endif
+        }
         else if( strcmp( p, "mtu" ) == 0 )
         {
             opt.mtu = atoi( q );
@@ -267,25 +284,122 @@
     }
 }
 
+#if defined(MBEDTLS_TIMING_C)
 /* Return elapsed time in milliseconds since the first call */
-static unsigned long ellapsed_time( void )
+static unsigned ellapsed_time( void )
 {
-#if defined(_WIN32)
-    return( 0 );
-#else
-    static struct timeval ref = { 0, 0 };
-    struct timeval now;
+    static int initialized = 0;
+    static struct mbedtls_timing_hr_time hires;
 
-    if( ref.tv_sec == 0 && ref.tv_usec == 0 )
+    if( initialized == 0 )
     {
-        gettimeofday( &ref, NULL );
+        (void) mbedtls_timing_get_timer( &hires, 1 );
+        initialized = 1;
         return( 0 );
     }
 
-    gettimeofday( &now, NULL );
-    return( 1000 * ( now.tv_sec  - ref.tv_sec )
-                 + ( now.tv_usec - ref.tv_usec ) / 1000 );
-#endif
+    return( mbedtls_timing_get_timer( &hires, 0 ) );
+}
+
+typedef struct
+{
+    mbedtls_net_context *ctx;
+
+    const char *description;
+
+    unsigned packet_lifetime;
+    unsigned num_datagrams;
+
+    unsigned char data[MAX_MSG_SIZE];
+    size_t len;
+
+} ctx_buffer;
+
+static ctx_buffer outbuf[2];
+
+static int ctx_buffer_flush( ctx_buffer *buf )
+{
+    int ret;
+
+    mbedtls_printf( "  %05u flush    %s: %u bytes, %u datagrams, last %u ms\n",
+                    ellapsed_time(), buf->description,
+                    (unsigned) buf->len, buf->num_datagrams,
+                    ellapsed_time() - buf->packet_lifetime );
+
+    ret = mbedtls_net_send( buf->ctx, buf->data, buf->len );
+
+    buf->len           = 0;
+    buf->num_datagrams = 0;
+
+    return( ret );
+}
+
+static unsigned ctx_buffer_time_remaining( ctx_buffer *buf )
+{
+    unsigned const cur_time = ellapsed_time();
+
+    if( buf->num_datagrams == 0 )
+        return( (unsigned) -1 );
+
+    if( cur_time - buf->packet_lifetime >= opt.pack )
+        return( 0 );
+
+    return( opt.pack - ( cur_time - buf->packet_lifetime ) );
+}
+
+static int ctx_buffer_append( ctx_buffer *buf,
+                              const unsigned char * data,
+                              size_t len )
+{
+    int ret;
+
+    if( len > (size_t) INT_MAX )
+        return( -1 );
+
+    if( len > sizeof( buf->data ) )
+    {
+        mbedtls_printf( "  ! buffer size %u too large (max %u)\n",
+                        (unsigned) len, (unsigned) sizeof( buf->data ) );
+        return( -1 );
+    }
+
+    if( sizeof( buf->data ) - buf->len < len )
+    {
+        if( ( ret = ctx_buffer_flush( buf ) ) <= 0 )
+            return( ret );
+    }
+
+    memcpy( buf->data + buf->len, data, len );
+
+    buf->len += len;
+    if( ++buf->num_datagrams == 1 )
+        buf->packet_lifetime = ellapsed_time();
+
+    return( (int) len );
+}
+#endif /* MBEDTLS_TIMING_C */
+
+static int dispatch_data( mbedtls_net_context *ctx,
+                          const unsigned char * data,
+                          size_t len )
+{
+#if defined(MBEDTLS_TIMING_C)
+    ctx_buffer *buf = NULL;
+    if( opt.pack > 0 )
+    {
+        if( outbuf[0].ctx == ctx )
+            buf = &outbuf[0];
+        else if( outbuf[1].ctx == ctx )
+            buf = &outbuf[1];
+
+        if( buf == NULL )
+            return( -1 );
+
+        return( ctx_buffer_append( buf, data, len ) );
+    }
+#endif /* MBEDTLS_TIMING_C */
+
+    return( mbedtls_net_send( ctx, data, len ) );
 }
 
 typedef struct
@@ -300,12 +414,22 @@
 /* Print packet. Outgoing packets come with a reason (forward, dupl, etc.) */
 void print_packet( const packet *p, const char *why )
 {
+#if defined(MBEDTLS_TIMING_C)
     if( why == NULL )
-        mbedtls_printf( "  %05lu %s %s (%u bytes)\n",
+        mbedtls_printf( "  %05u dispatch %s %s (%u bytes)\n",
                 ellapsed_time(), p->way, p->type, p->len );
     else
-        mbedtls_printf( "        %s %s (%u bytes): %s\n",
+        mbedtls_printf( "  %05u dispatch %s %s (%u bytes): %s\n",
+                ellapsed_time(), p->way, p->type, p->len, why );
+#else
+    if( why == NULL )
+        mbedtls_printf( "        dispatch %s %s (%u bytes)\n",
+                p->way, p->type, p->len );
+    else
+        mbedtls_printf( "        dispatch %s %s (%u bytes): %s\n",
                 p->way, p->type, p->len, why );
+#endif
+
     fflush( stdout );
 }
 
@@ -320,20 +444,28 @@
     {
         unsigned char buf[MAX_MSG_SIZE];
         memcpy( buf, p->buf, p->len );
-        ++buf[p->len - 1];
 
-        print_packet( p, "corrupted" );
-        if( ( ret = mbedtls_net_send( dst, buf, p->len ) ) <= 0 )
+        if( p->len <= 13 )
         {
-            mbedtls_printf( "  ! mbedtls_net_send returned %d\n", ret );
+            mbedtls_printf( "  ! can't corrupt empty AD record" );
+        }
+        else
+        {
+            ++buf[13];
+            print_packet( p, "corrupted" );
+        }
+
+        if( ( ret = dispatch_data( dst, buf, p->len ) ) <= 0 )
+        {
+            mbedtls_printf( "  ! dispatch returned %d\n", ret );
             return( ret );
         }
     }
 
     print_packet( p, why );
-    if( ( ret = mbedtls_net_send( dst, p->buf, p->len ) ) <= 0 )
+    if( ( ret = dispatch_data( dst, p->buf, p->len ) ) <= 0 )
     {
-        mbedtls_printf( "  ! mbedtls_net_send returned %d\n", ret );
+        mbedtls_printf( "  ! dispatch returned %d\n", ret );
         return( ret );
     }
 
@@ -344,9 +476,9 @@
     {
         print_packet( p, "duplicated" );
 
-        if( ( ret = mbedtls_net_send( dst, p->buf, p->len ) ) <= 0 )
+        if( ( ret = dispatch_data( dst, p->buf, p->len ) ) <= 0 )
         {
-            mbedtls_printf( "  ! mbedtls_net_send returned %d\n", ret );
+            mbedtls_printf( "  ! dispatch returned %d\n", ret );
             return( ret );
         }
     }
@@ -472,6 +604,12 @@
 
     mbedtls_net_context listen_fd, client_fd, server_fd;
 
+#if defined( MBEDTLS_TIMING_C )
+    struct timeval tm;
+#endif
+
+    struct timeval *tm_ptr = NULL;
+
     int nb_fds;
     fd_set read_fds;
 
@@ -560,14 +698,65 @@
         nb_fds = listen_fd.fd;
     ++nb_fds;
 
+#if defined(MBEDTLS_TIMING_C)
+    if( opt.pack > 0 )
+    {
+        outbuf[0].ctx = &server_fd;
+        outbuf[0].description = "S <- C";
+        outbuf[0].num_datagrams = 0;
+        outbuf[0].len = 0;
+
+        outbuf[1].ctx = &client_fd;
+        outbuf[1].description = "S -> C";
+        outbuf[1].num_datagrams = 0;
+        outbuf[1].len = 0;
+    }
+#endif /* MBEDTLS_TIMING_C */
+
     while( 1 )
     {
+#if defined(MBEDTLS_TIMING_C)
+        if( opt.pack > 0 )
+        {
+            unsigned max_wait_server, max_wait_client, max_wait;
+            max_wait_server = ctx_buffer_time_remaining( &outbuf[0] );
+            max_wait_client = ctx_buffer_time_remaining( &outbuf[1] );
+
+            max_wait = (unsigned) -1;
+
+            if( max_wait_server == 0 )
+                ctx_buffer_flush( &outbuf[0] );
+            else
+                max_wait = max_wait_server;
+
+            if( max_wait_client == 0 )
+                ctx_buffer_flush( &outbuf[1] );
+            else
+            {
+                if( max_wait_client < max_wait )
+                    max_wait = max_wait_client;
+            }
+
+            if( max_wait != (unsigned) -1 )
+            {
+                tm.tv_sec  = max_wait / 1000;
+                tm.tv_usec = ( max_wait % 1000 ) * 1000;
+
+                tm_ptr = &tm;
+            }
+            else
+            {
+                tm_ptr = NULL;
+            }
+        }
+#endif /* MBEDTLS_TIMING_C */
+
         FD_ZERO( &read_fds );
         FD_SET( server_fd.fd, &read_fds );
         FD_SET( client_fd.fd, &read_fds );
         FD_SET( listen_fd.fd, &read_fds );
 
-        if( ( ret = select( nb_fds, &read_fds, NULL, NULL, NULL ) ) <= 0 )
+        if( ( ret = select( nb_fds, &read_fds, NULL, NULL, tm_ptr ) ) < 0 )
         {
             perror( "select" );
             goto exit;
@@ -589,6 +778,7 @@
                                         &client_fd, &server_fd ) ) != 0 )
                 goto accept;
         }
+
     }
 
 exit:
diff --git a/programs/test/udp_proxy_wrapper.sh b/programs/test/udp_proxy_wrapper.sh
new file mode 100755
index 0000000..29033d5
--- /dev/null
+++ b/programs/test/udp_proxy_wrapper.sh
@@ -0,0 +1,117 @@
+#!/bin/sh
+# -*-sh-basic-offset: 4-*-
+# Usage: udp_proxy_wrapper.sh [PROXY_PARAM...] -- [SERVER_PARAM...]
+
+set -u
+
+MBEDTLS_BASE="$(dirname -- "$0")/../.."
+TPXY_BIN="$MBEDTLS_BASE/programs/test/udp_proxy"
+SRV_BIN="$MBEDTLS_BASE/programs/ssl/ssl_server2"
+
+: ${VERBOSE:=0}
+
+stop_proxy() {
+    if [ -n "${tpxy_pid:-}" ]; then
+        echo
+        echo "  * Killing proxy (pid $tpxy_pid) ..."
+        kill $tpxy_pid
+    fi
+}
+
+stop_server() {
+    if [ -n "${srv_pid:-}" ]; then
+        echo
+        echo "  * Killing server (pid $srv_pid) ..."
+        kill $srv_pid >/dev/null 2>/dev/null
+    fi
+}
+
+cleanup() {
+    stop_server
+    stop_proxy
+    exit 129
+}
+
+trap cleanup INT TERM HUP
+
+# Extract the proxy parameters
+tpxy_cmd_snippet='"$TPXY_BIN"'
+while [ $# -ne 0 ] && [ "$1" != "--" ]; do
+    tail="$1" quoted=""
+    while [ -n "$tail" ]; do
+        case "$tail" in
+            *\'*) quoted="${quoted}${tail%%\'*}'\\''" tail="${tail#*\'}";;
+            *) quoted="${quoted}${tail}"; tail=; false;;
+        esac
+    done
+    tpxy_cmd_snippet="$tpxy_cmd_snippet '$quoted'"
+    shift
+done
+unset tail quoted
+if [ $# -eq 0 ]; then
+    echo "  * No server arguments (must be preceded by \" -- \") - exit"
+    exit 3
+fi
+shift
+
+dtls_enabled=
+ipv6_in_use=
+server_port_orig=
+server_addr_orig=
+for param; do
+    case "$param" in
+        server_port=*) server_port_orig="${param#*=}";;
+        server_addr=*:*) server_addr_orig="${param#*=}"; ipv6_in_use=1;;
+        server_addr=*) server_addr_orig="${param#*=}";;
+        dtls=[!0]*) dtls_enabled=1;;
+    esac
+done
+
+if [ -z "$dtls_enabled" ] || [ -n "$ipv6_in_use" ]; then
+    echo >&2 "$0: Couldn't find DTLS enabling, or IPv6 is in use - immediate fallback to server application..."
+    if [ $VERBOSE -gt 0 ]; then
+        echo "[ $SRV_BIN $* ]"
+    fi
+    exec "$SRV_BIN" "$@"
+fi
+
+if [ -z "$server_port_orig" ]; then
+    server_port_orig=4433
+fi
+echo "  * Server port:       $server_port_orig"
+tpxy_cmd_snippet="$tpxy_cmd_snippet \"listen_port=\$server_port_orig\""
+tpxy_cmd_snippet="$tpxy_cmd_snippet \"server_port=\$server_port\""
+
+if [ -n "$server_addr_orig" ]; then
+    echo "  * Server address:    $server_addr_orig"
+    tpxy_cmd_snippet="$tpxy_cmd_snippet \"server_addr=\$server_addr_orig\""
+    tpxy_cmd_snippet="$tpxy_cmd_snippet \"listen_addr=\$server_addr_orig\""
+fi
+
+server_port=$(( server_port_orig + 1 ))
+set -- "$@" "server_port=$server_port"
+echo "  * Intermediate port: $server_port"
+
+echo "  * Start proxy in background ..."
+if [ $VERBOSE -gt 0 ]; then
+    echo "[ $tpxy_cmd_snippet ]"
+fi
+eval exec "$tpxy_cmd_snippet" >/dev/null 2>&1 &
+tpxy_pid=$!
+
+if [ $VERBOSE -gt 0 ]; then
+    echo "  * Proxy ID:          $TPXY_PID"
+fi
+
+echo "  * Starting server ..."
+if [ $VERBOSE -gt 0 ]; then
+    echo "[ $SRV_BIN $* ]"
+fi
+
+exec "$SRV_BIN" "$@" >&2 &
+srv_pid=$!
+
+wait $srv_pid
+
+stop_proxy
+return 0
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 2d6b71a..f7fa532 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -465,9 +465,12 @@
         eval "$CLI_CMD" >> $CLI_OUT 2>&1 &
         wait_client_done
 
+        sleep 0.05
+
         # terminate the server (and the proxy)
         kill $SRV_PID
         wait $SRV_PID
+
         if [ -n "$PXY_CMD" ]; then
             kill $PXY_PID >/dev/null 2>&1
             wait $PXY_PID
@@ -631,16 +634,19 @@
 get_options "$@"
 
 # sanity checks, avoid an avalanche of errors
-if [ ! -x "$P_SRV" ]; then
-    echo "Command '$P_SRV' is not an executable file"
+P_SRV_BIN="${P_SRV%%[  ]*}"
+P_CLI_BIN="${P_CLI%%[  ]*}"
+P_PXY_BIN="${P_PXY%%[  ]*}"
+if [ ! -x "$P_SRV_BIN" ]; then
+    echo "Command '$P_SRV_BIN' is not an executable file"
     exit 1
 fi
-if [ ! -x "$P_CLI" ]; then
-    echo "Command '$P_CLI' is not an executable file"
+if [ ! -x "$P_CLI_BIN" ]; then
+    echo "Command '$P_CLI_BIN' is not an executable file"
     exit 1
 fi
-if [ ! -x "$P_PXY" ]; then
-    echo "Command '$P_PXY' is not an executable file"
+if [ ! -x "$P_PXY_BIN" ]; then
+    echo "Command '$P_PXY_BIN' is not an executable file"
     exit 1
 fi
 if [ "$MEMCHECK" -gt 0 ]; then
@@ -2704,6 +2710,118 @@
             -C "mbedtls_ssl_handshake returned" \
             -c "Read from server: .* bytes read"
 
+# Tests for event-driven I/O: exercise a variety of handshake flows
+
+run_test    "Event-driven I/O: basic handshake" \
+            "$P_SRV event=1 tickets=0 auth_mode=none" \
+            "$P_CLI event=1 tickets=0" \
+            0 \
+            -S "mbedtls_ssl_handshake returned" \
+            -C "mbedtls_ssl_handshake returned" \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O: client auth" \
+            "$P_SRV event=1 tickets=0 auth_mode=required" \
+            "$P_CLI event=1 tickets=0" \
+            0 \
+            -S "mbedtls_ssl_handshake returned" \
+            -C "mbedtls_ssl_handshake returned" \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O: ticket" \
+            "$P_SRV event=1 tickets=1 auth_mode=none" \
+            "$P_CLI event=1 tickets=1" \
+            0 \
+            -S "mbedtls_ssl_handshake returned" \
+            -C "mbedtls_ssl_handshake returned" \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O: ticket + client auth" \
+            "$P_SRV event=1 tickets=1 auth_mode=required" \
+            "$P_CLI event=1 tickets=1" \
+            0 \
+            -S "mbedtls_ssl_handshake returned" \
+            -C "mbedtls_ssl_handshake returned" \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O: ticket + client auth + resume" \
+            "$P_SRV event=1 tickets=1 auth_mode=required" \
+            "$P_CLI event=1 tickets=1 reconnect=1" \
+            0 \
+            -S "mbedtls_ssl_handshake returned" \
+            -C "mbedtls_ssl_handshake returned" \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O: ticket + resume" \
+            "$P_SRV event=1 tickets=1 auth_mode=none" \
+            "$P_CLI event=1 tickets=1 reconnect=1" \
+            0 \
+            -S "mbedtls_ssl_handshake returned" \
+            -C "mbedtls_ssl_handshake returned" \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O: session-id resume" \
+            "$P_SRV event=1 tickets=0 auth_mode=none" \
+            "$P_CLI event=1 tickets=0 reconnect=1" \
+            0 \
+            -S "mbedtls_ssl_handshake returned" \
+            -C "mbedtls_ssl_handshake returned" \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O, DTLS: basic handshake" \
+            "$P_SRV dtls=1 event=1 tickets=0 auth_mode=none" \
+            "$P_CLI dtls=1 event=1 tickets=0" \
+            0 \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O, DTLS: client auth" \
+            "$P_SRV dtls=1 event=1 tickets=0 auth_mode=required" \
+            "$P_CLI dtls=1 event=1 tickets=0" \
+            0 \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O, DTLS: ticket" \
+            "$P_SRV dtls=1 event=1 tickets=1 auth_mode=none" \
+            "$P_CLI dtls=1 event=1 tickets=1" \
+            0 \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O, DTLS: ticket + client auth" \
+            "$P_SRV dtls=1 event=1 tickets=1 auth_mode=required" \
+            "$P_CLI dtls=1 event=1 tickets=1" \
+            0 \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O, DTLS: ticket + client auth + resume" \
+            "$P_SRV dtls=1 event=1 tickets=1 auth_mode=required" \
+            "$P_CLI dtls=1 event=1 tickets=1 reconnect=1" \
+            0 \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O, DTLS: ticket + resume" \
+            "$P_SRV dtls=1 event=1 tickets=1 auth_mode=none" \
+            "$P_CLI dtls=1 event=1 tickets=1 reconnect=1" \
+            0 \
+            -c "Read from server: .* bytes read"
+
+run_test    "Event-driven I/O, DTLS: session-id resume" \
+            "$P_SRV dtls=1 event=1 tickets=0 auth_mode=none" \
+            "$P_CLI dtls=1 event=1 tickets=0 reconnect=1" \
+            0 \
+            -c "Read from server: .* bytes read"
+
+# This test demonstrates the need for the mbedtls_ssl_check_pending function.
+# During session resumption, the client will send its ApplicationData record
+# within the same datagram as the Finished messages. In this situation, the
+# server MUST NOT idle on the underlying transport after handshake completion,
+# because the ApplicationData request has already been queued internally.
+run_test    "Event-driven I/O, DTLS: session-id resume, UDP packing" \
+            -p "$P_PXY pack=50" \
+            "$P_SRV dtls=1 event=1 tickets=0 auth_mode=required" \
+            "$P_CLI dtls=1 event=1 tickets=0 reconnect=1" \
+            0 \
+            -c "Read from server: .* bytes read"
+
 # Tests for version negotiation
 
 run_test    "Version check: all -> 1.2" \
@@ -4195,8 +4313,8 @@
             0 \
             -c "replayed record" \
             -s "replayed record" \
-            -c "discarding invalid record" \
-            -s "discarding invalid record" \
+            -c "record from another epoch" \
+            -s "record from another epoch" \
             -S "resend" \
             -s "Extra-header:" \
             -c "HTTP/1.0 200 OK"
@@ -4208,13 +4326,29 @@
             0 \
             -c "replayed record" \
             -S "replayed record" \
-            -c "discarding invalid record" \
-            -s "discarding invalid record" \
+            -c "record from another epoch" \
+            -s "record from another epoch" \
             -c "resend" \
             -s "resend" \
             -s "Extra-header:" \
             -c "HTTP/1.0 200 OK"
 
+run_test    "DTLS proxy: multiple records in same datagram" \
+            -p "$P_PXY pack=50" \
+            "$P_SRV dtls=1 debug_level=2" \
+            "$P_CLI dtls=1 debug_level=2" \
+            0 \
+            -c "next record in same datagram" \
+            -s "next record in same datagram"
+
+run_test    "DTLS proxy: multiple records in same datagram, duplicate every packet" \
+            -p "$P_PXY pack=50 duplicate=1" \
+            "$P_SRV dtls=1 debug_level=2" \
+            "$P_CLI dtls=1 debug_level=2" \
+            0 \
+            -c "next record in same datagram" \
+            -s "next record in same datagram"
+
 run_test    "DTLS proxy: inject invalid AD record, default badmac_limit" \
             -p "$P_PXY bad_ad=1" \
             "$P_SRV dtls=1 debug_level=1" \
@@ -4270,8 +4404,6 @@
             0 \
             -c "record from another epoch" \
             -s "record from another epoch" \
-            -c "discarding invalid record" \
-            -s "discarding invalid record" \
             -s "Extra-header:" \
             -c "HTTP/1.0 200 OK"