diff --git a/ChangeLog b/ChangeLog
index 1d39172..e3e77f2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,69 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS X.X.X branch released XXXX-XX-XX
+
+Bugfix
+   * Allow loading symlinked certificates. Fixes #3005. Reported and fixed
+     by Jonathan Bennett <JBennett@incomsystems.biz> via #3008.
+   * Fix an unchecked call to mbedtls_md() in the x509write module.
+   * Fix build failure with MBEDTLS_ZLIB_SUPPORT enabled. Reported by
+     Jack Lloyd in #2859. Fix submitted by jiblime in #2963.
+
 = mbed TLS 2.20.0 branch released 2020-01-15
 
+Default behavior changes
+   * The initial seeding of a CTR_DRBG instance makes a second call to the
+     entropy function to obtain entropy for a nonce if the entropy size is less
+     than 3/2 times the key size. In case you want to disable the extra call to
+     grab entropy, you can call mbedtls_ctr_drbg_set_nonce_len() to force the
+     nonce length to 0.
+
+Security
+   * Enforce that mbedtls_entropy_func() gathers a total of
+     MBEDTLS_ENTROPY_BLOCK_SIZE bytes or more from strong sources. In the
+     default configuration, on a platform with a single entropy source, the
+     entropy module formerly only grabbed 32 bytes, which is good enough for
+     security if the source is genuinely strong, but less than the expected 64
+     bytes (size of the entropy accumulator).
+   * Zeroize local variables in mbedtls_internal_aes_encrypt() and
+     mbedtls_internal_aes_decrypt() before exiting the function. The value of
+     these variables can be used to recover the last round key. To follow best
+     practice and to limit the impact of buffer overread vulnerabilities (like
+     Heartbleed) we need to zeroize them before exiting the function.
+     Issue reported by Tuba Yavuz, Farhaan Fowze, Ken (Yihang) Bai,
+     Grant Hernandez, and Kevin Butler (University of Florida) and
+     Dave Tian (Purdue University).
+   * Fix side channel vulnerability in ECDSA. Our bignum implementation is not
+     constant time/constant trace, so side channel attacks can retrieve the
+     blinded value, factor it (as it is smaller than RSA keys and not guaranteed
+     to have only large prime factors), and then, by brute force, recover the
+     key. Reported by Alejandro Cabrera Aldaya and Billy Brumley.
+   * Fix side channel vulnerability in ECDSA key generation. Obtaining precise
+     timings on the comparison in the key generation enabled the attacker to
+     learn leading bits of the ephemeral key used during ECDSA signatures and to
+     recover the private key. Reported by Jeremy Dubeuf.
+   * Catch failure of AES functions in mbedtls_ctr_drbg_random(). Uncaught
+     failures could happen with alternative implementations of AES. Bug
+     reported and fix proposed by Johan Uppman Bruce and Christoffer Lauri,
+     Sectra.
+
+Features
+   * Key derivation inputs in the PSA API can now either come from a key object
+     or from a buffer regardless of the step type.
+   * The CTR_DRBG module can grab a nonce from the entropy source during the
+     initial seeding. The default nonce length is chosen based on the key size
+     to achieve the security strength defined by NIST SP 800-90A. You can
+     change it with mbedtls_ctr_drbg_set_nonce_len().
+   * Add ENUMERATED tag support to the ASN.1 module. Contributed by
+     msopiha-linaro in ARMmbed/mbed-crypto#307.
+
+API changes
+   * In the PSA API, forbid zero-length keys. To pass a zero-length input to a
+     key derivation function, use a buffer instead (this is now always
+     possible).
+   * Rename psa_asymmetric_sign() to psa_sign_hash() and
+     psa_asymmetric_verify() to psa_verify_hash().
+
 Bugfix
    * Fix an incorrect size in a debugging message. Reported and fix
      submitted by irwir. Fixes #2717.
@@ -9,10 +71,40 @@
      Reported and fix submitted by irwir. Fixes #2800.
    * Remove a useless assignment. Reported and fix submitted by irwir.
      Fixes #2801.
+   * Fix a buffer overflow in the PSA HMAC code when using a long key with an
+     unsupported algorithm. Fixes ARMmbed/mbed-crypto#254.
+   * Fix mbedtls_asn1_get_int to support any number of leading zeros. Credit
+     to OSS-Fuzz for finding a bug in an intermediate version of the fix.
+   * Fix mbedtls_asn1_get_bitstring_null to correctly parse bitstrings of at
+     most 2 bytes.
+   * mbedtls_ctr_drbg_set_entropy_len() and
+     mbedtls_hmac_drbg_set_entropy_len() now work if you call them before
+     mbedtls_ctr_drbg_seed() or mbedtls_hmac_drbg_seed().
+   * Fix some false-positive uninitialized variable warnings. Fix contributed
+     by apple-ihack-geek in #2663.
+
+Changes
+   * Remove the technical possibility to define custom mbedtls_md_info
+     structures, which was exposed only in an internal header.
+   * psa_close_key(0) and psa_destroy_key(0) now succeed (doing nothing, as
+     before).
+   * Variables containing error codes are now initialized to an error code
+     rather than success, so that coding mistakes or memory corruption tends to
+     cause functions to return this error code rather than a success. There are
+     no known instances where this changes the behavior of the library: this is
+     merely a robustness improvement. ARMmbed/mbed-crypto#323
+   * Remove a useless call to mbedtls_ecp_group_free(). Contributed by
+     Alexander Krizhanovsky in ARMmbed/mbed-crypto#210.
+   * Speed up PBKDF2 by caching the digest calculation. Contributed by Jack
+     Lloyd and Fortanix Inc in ARMmbed/mbed-crypto#277.
+   * Small performance improvement of mbedtls_mpi_div_mpi(). Contributed by
+     Alexander Krizhanovsky in ARMmbed/mbed-crypto#308.
 
 = mbed TLS 2.19.1 branch released 2019-09-16
 
 Features
+   * Declare include headers as PUBLIC to propagate to CMake project consumers
+     Contributed by Zachary J. Fields in PR #2949.
    * Add nss_keylog to ssl_client2 and ssl_server2, enabling easier analysis of
      TLS sessions with tools like Wireshark.
 
diff --git a/crypto b/crypto
index d27a884..819799c 160000
--- a/crypto
+++ b/crypto
@@ -1 +1 @@
-Subproject commit d27a88438fe785f0906c01e3216044d1c98be875
+Subproject commit 819799cfc68e4c4381673a8a27af19802c8263f2
diff --git a/doxygen/input/doc_mainpage.h b/doxygen/input/doc_mainpage.h
index d5ead37..5b5aefb 100644
--- a/doxygen/input/doc_mainpage.h
+++ b/doxygen/input/doc_mainpage.h
@@ -24,7 +24,7 @@
  */
 
 /**
- * @mainpage mbed TLS v2.19.1 source code documentation
+ * @mainpage mbed TLS v2.20.0 source code documentation
  *
  * This documentation describes the internal structure of mbed TLS.  It was
  * automatically generated from specially formatted comment blocks in
diff --git a/doxygen/mbedtls.doxyfile b/doxygen/mbedtls.doxyfile
index eb2d96e..47a9740 100644
--- a/doxygen/mbedtls.doxyfile
+++ b/doxygen/mbedtls.doxyfile
@@ -28,7 +28,7 @@
 # identify the project. Note that if you do not use Doxywizard you need
 # to put quotes around the project name if it contains spaces.
 
-PROJECT_NAME           = "mbed TLS v2.19.1"
+PROJECT_NAME           = "mbed TLS v2.20.0"
 
 # The PROJECT_NUMBER tag can be used to enter a project or revision number.
 # This could be handy for archiving the generated documentation or
diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index c2f2bd4..a3ee3e4 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -1,5 +1,11 @@
 option(INSTALL_MBEDTLS_HEADERS "Install mbed TLS headers." ON)
 
+# Declare include headers as PUBLIC to propogate to project consumers
+target_include_directories(
+    mbedtls
+    PUBLIC ${CMAKE_CURRENT_LIST_DIR}
+)
+
 if(INSTALL_MBEDTLS_HEADERS)
 
     file(GLOB headers "mbedtls/*.h")
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index f703da9..b8c7f0a 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -319,7 +319,8 @@
     mbedtls_ecdh_context ecdh_ctx;              /*!<  ECDH key exchange       */
 
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
-    psa_ecc_curve_t ecdh_psa_curve;
+    psa_key_type_t ecdh_psa_type;
+    uint16_t ecdh_bits;
     psa_key_handle_t ecdh_psa_privkey;
     unsigned char ecdh_psa_peerkey[MBEDTLS_PSA_MAX_EC_PUBKEY_LENGTH];
     size_t ecdh_psa_peerkey_len;
diff --git a/include/mbedtls/version.h b/include/mbedtls/version.h
index ae694ee..d4e5d54 100644
--- a/include/mbedtls/version.h
+++ b/include/mbedtls/version.h
@@ -39,17 +39,17 @@
  * Major, Minor, Patchlevel
  */
 #define MBEDTLS_VERSION_MAJOR  2
-#define MBEDTLS_VERSION_MINOR  19
-#define MBEDTLS_VERSION_PATCH  1
+#define MBEDTLS_VERSION_MINOR  20
+#define MBEDTLS_VERSION_PATCH  0
 
 /**
  * The single version number has the following structure:
  *    MMNNPP00
  *    Major version | Minor version | Patch version
  */
-#define MBEDTLS_VERSION_NUMBER         0x02130100
-#define MBEDTLS_VERSION_STRING         "2.19.1"
-#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.19.1"
+#define MBEDTLS_VERSION_NUMBER         0x02140000
+#define MBEDTLS_VERSION_STRING         "2.20.0"
+#define MBEDTLS_VERSION_STRING_FULL    "mbed TLS 2.20.0"
 
 #if defined(MBEDTLS_VERSION_C)
 
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 5e36a5b..d990d43 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -174,14 +174,14 @@
 if(USE_SHARED_MBEDTLS_LIBRARY)
 
     add_library(mbedx509 SHARED ${src_x509})
-    set_target_properties(mbedx509 PROPERTIES VERSION 2.19.1 SOVERSION 1)
+    set_target_properties(mbedx509 PROPERTIES VERSION 2.20.0 SOVERSION 1)
     target_link_libraries(mbedx509 ${libs} mbedcrypto)
     target_include_directories(mbedx509
         PUBLIC ${MBEDTLS_DIR}/include/
         PUBLIC ${MBEDTLS_DIR}/crypto/include/)
 
     add_library(mbedtls SHARED ${src_tls})
-    set_target_properties(mbedtls PROPERTIES VERSION 2.19.1 SOVERSION 13)
+    set_target_properties(mbedtls PROPERTIES VERSION 2.20.0 SOVERSION 13)
     target_link_libraries(mbedtls ${libs} mbedx509)
     target_include_directories(mbedtls
         PUBLIC ${MBEDTLS_DIR}/include/
diff --git a/library/Makefile b/library/Makefile
index bc9363d..6fc110c 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -37,7 +37,7 @@
 
 SOEXT_TLS=so.13
 SOEXT_X509=so.1
-SOEXT_CRYPTO=so.3
+SOEXT_CRYPTO=so.4
 
 # Set AR_DASH= (empty string) to use an ar implementation that does not accept
 # the - prefix for command line options (e.g. llvm-ar)
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 1005bd9..0f6a26b 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -2244,6 +2244,7 @@
                                              unsigned char *end )
 {
     uint16_t tls_id;
+    size_t ecdh_bits = 0;
     uint8_t ecpoint_len;
     mbedtls_ssl_handshake_params *handshake = ssl->handshake;
 
@@ -2264,11 +2265,14 @@
     tls_id |= *(*p)++;
 
     /* Convert EC group to PSA key type. */
-    if( ( handshake->ecdh_psa_curve =
-          mbedtls_psa_parse_tls_ecc_group( tls_id ) ) == 0 )
+    if( ( handshake->ecdh_psa_type =
+          mbedtls_psa_parse_tls_ecc_group( tls_id, &ecdh_bits ) ) == 0 )
     {
         return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
     }
+    if( ecdh_bits > 0xffff )
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
+    handshake->ecdh_bits = (uint16_t) ecdh_bits;
 
     /*
      * Put peer's ECDH public key in the format understood by PSA.
@@ -2278,7 +2282,7 @@
     if( (size_t)( end - *p ) < ecpoint_len )
         return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
 
-    if( mbedtls_psa_tls_ecpoint_to_psa_ec( handshake->ecdh_psa_curve,
+    if( mbedtls_psa_tls_ecpoint_to_psa_ec(
                                     *p, ecpoint_len,
                                     handshake->ecdh_psa_peerkey,
                                     sizeof( handshake->ecdh_psa_peerkey ),
@@ -3257,11 +3261,8 @@
         key_attributes = psa_key_attributes_init();
         psa_set_key_usage_flags( &key_attributes, PSA_KEY_USAGE_DERIVE );
         psa_set_key_algorithm( &key_attributes, PSA_ALG_ECDH );
-        psa_set_key_type( &key_attributes,
-                          PSA_KEY_TYPE_ECC_KEY_PAIR( handshake->ecdh_psa_curve )
-                        );
-        psa_set_key_bits( &key_attributes,
-                          PSA_ECC_CURVE_BITS( handshake->ecdh_psa_curve ) );
+        psa_set_key_type( &key_attributes, handshake->ecdh_psa_type );
+        psa_set_key_bits( &key_attributes, handshake->ecdh_bits );
 
         /* Generate ECDH private key. */
         status = psa_generate_key( &key_attributes,
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 6cf7781..4f219a3 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1880,7 +1880,7 @@
 
     /* Allocate compression buffer */
 #if defined(MBEDTLS_ZLIB_SUPPORT)
-    if( session->compression == MBEDTLS_SSL_COMPRESS_DEFLATE &&
+    if( ssl->session_negotiate->compression == MBEDTLS_SSL_COMPRESS_DEFLATE &&
         ssl->compress_buf == NULL )
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "Allocating compression buffer" ) );
@@ -5446,7 +5446,7 @@
 #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
 
 /*
- * If applicable, decrypt (and decompress) record content
+ * If applicable, decrypt record content
  */
 static int ssl_prepare_record_content( mbedtls_ssl_context *ssl,
                                        mbedtls_record *rec )
@@ -5572,18 +5572,6 @@
 
     }
 
-#if defined(MBEDTLS_ZLIB_SUPPORT)
-    if( ssl->transform_in != NULL &&
-        ssl->session_in->compression == MBEDTLS_SSL_COMPRESS_DEFLATE )
-    {
-        if( ( ret = ssl_decompress_buf( ssl ) ) != 0 )
-        {
-            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_decompress_buf", ret );
-            return( ret );
-        }
-    }
-#endif /* MBEDTLS_ZLIB_SUPPORT */
-
 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
     if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
     {
@@ -6469,6 +6457,26 @@
     ssl->in_len[0] = (unsigned char)( rec.data_len >> 8 );
     ssl->in_len[1] = (unsigned char)( rec.data_len      );
 
+#if defined(MBEDTLS_ZLIB_SUPPORT)
+    if( ssl->transform_in != NULL &&
+        ssl->session_in->compression == MBEDTLS_SSL_COMPRESS_DEFLATE )
+    {
+        if( ( ret = ssl_decompress_buf( ssl ) ) != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_RET( 1, "ssl_decompress_buf", ret );
+            return( ret );
+        }
+
+        /* Check actual (decompress) record content length against
+         * configured maximum. */
+        if( ssl->in_msglen > MBEDTLS_SSL_IN_CONTENT_LEN )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+    }
+#endif /* MBEDTLS_ZLIB_SUPPORT */
+
     return( 0 );
 }
 
diff --git a/library/x509_crt.c b/library/x509_crt.c
index 38e69cc..ca60011 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1613,7 +1613,7 @@
             goto cleanup;
         }
 
-        if( !S_ISREG( sb.st_mode ) )
+        if( !( S_ISREG( sb.st_mode ) || S_ISLNK( sb.st_mode ) ) )
             continue;
 
         // Ignore parse errors
diff --git a/library/x509write_csr.c b/library/x509write_csr.c
index 0c3c396..7c51798 100644
--- a/library/x509write_csr.c
+++ b/library/x509write_csr.c
@@ -214,7 +214,9 @@
         return( MBEDTLS_ERR_X509_FATAL_ERROR );
     }
 #else /* MBEDTLS_USE_PSA_CRYPTO */
-    mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash );
+    ret = mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash );
+    if( ret != 0 )
+        return( ret );
 #endif
     if( ( ret = mbedtls_pk_sign( ctx->key, ctx->md_alg, hash, 0, sig, &sig_len,
                                  f_rng, p_rng ) ) != 0 )
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index 8f0d3b5..c188900 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -619,6 +619,7 @@
         if( fwrite( nss_keylog_line, 1, len, f ) != len )
         {
             ret = -1;
+            fclose( f );
             goto exit;
         }
 
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index e76b9d4..1ad11ff 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -697,6 +697,45 @@
     if_build_succeeded tests/compat.sh
 }
 
+component_test_zlib_make() {
+    msg "build: zlib enabled, make"
+    scripts/config.py set MBEDTLS_ZLIB_SUPPORT
+    make ZLIB=1 CFLAGS='-Werror -O1'
+
+    msg "test: main suites (zlib, make)"
+    make test
+
+    msg "test: ssl-opt.sh (zlib, make)"
+    if_build_succeeded tests/ssl-opt.sh
+}
+support_test_zlib_make () {
+    base=support_test_zlib_$$
+    cat <<'EOF' > ${base}.c
+#include "zlib.h"
+int main(void) { return 0; }
+EOF
+    gcc -o ${base}.exe ${base}.c -lz 2>/dev/null
+    ret=$?
+    rm -f ${base}.*
+    return $ret
+}
+
+component_test_zlib_cmake() {
+    msg "build: zlib enabled, cmake"
+    scripts/config.py set MBEDTLS_ZLIB_SUPPORT
+    cmake -D ENABLE_ZLIB_SUPPORT=On -D CMAKE_BUILD_TYPE:String=Check .
+    make
+
+    msg "test: main suites (zlib, cmake)"
+    make test
+
+    msg "test: ssl-opt.sh (zlib, cmake)"
+    if_build_succeeded tests/ssl-opt.sh
+}
+support_test_zlib_cmake () {
+    support_test_zlib_make "$@"
+}
+
 component_test_ref_configs () {
     msg "test/build: ref-configs (ASan build)" # ~ 6 min 20s
     CC=gcc cmake -D CMAKE_BUILD_TYPE:String=Asan .
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index afaae69..3d0ca87 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -996,6 +996,18 @@
             -s "Protocol is DTLSv1.2" \
             -s "Ciphersuite is TLS-ECDHE-RSA-WITH-CHACHA20-POLY1305-SHA256"
 
+requires_config_enabled MBEDTLS_ZLIB_SUPPORT
+run_test    "Default (compression enabled)" \
+            "$P_SRV debug_level=3" \
+            "$P_CLI debug_level=3" \
+            0 \
+            -s "Allocating compression buffer" \
+            -c "Allocating compression buffer" \
+            -s "Record expansion is unknown (compression)" \
+            -c "Record expansion is unknown (compression)" \
+            -S "error" \
+            -C "error"
+
 requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "CA callback on client" \
             "$P_SRV debug_level=3" \
diff --git a/tests/suites/host_test.function b/tests/suites/host_test.function
index 9e56ca3..b956c0c 100644
--- a/tests/suites/host_test.function
+++ b/tests/suites/host_test.function
@@ -525,15 +525,6 @@
     mbedtls_memory_buffer_alloc_init( alloc_buf, sizeof( alloc_buf ) );
 #endif
 
-    if( outcome_file_name != NULL )
-    {
-        outcome_file = fopen( outcome_file_name, "a" );
-        if( outcome_file == NULL )
-        {
-            mbedtls_fprintf( stderr, "Unable to open outcome file. Continuing anyway.\n" );
-        }
-    }
-
     /*
      * The C standard doesn't guarantee that all-bits-0 is the representation
      * of a NULL pointer. We do however use that in our code for initializing
@@ -555,6 +546,15 @@
         return( 1 );
     }
 
+    if( outcome_file_name != NULL )
+    {
+        outcome_file = fopen( outcome_file_name, "a" );
+        if( outcome_file == NULL )
+        {
+            mbedtls_fprintf( stderr, "Unable to open outcome file. Continuing anyway.\n" );
+        }
+    }
+
     while( arg_index < argc )
     {
         next_arg = argv[arg_index];
@@ -607,6 +607,8 @@
         {
             mbedtls_fprintf( stderr, "Failed to open test file: %s\n",
                              test_filename );
+            if( outcome_file != NULL )
+                fclose( outcome_file );
             return( 1 );
         }
 
diff --git a/tests/suites/test_suite_ssl.data b/tests/suites/test_suite_ssl.data
index 83ef691..5f4dc67 100644
--- a/tests/suites/test_suite_ssl.data
+++ b/tests/suites/test_suite_ssl.data
@@ -35,34 +35,169 @@
 ssl_mock_sanity:
 
 Test mock blocking TCP connection
-ssl_mock_tcp:1:0:0
+ssl_mock_tcp:1
 
-Test mock non-blocking TCP connection: would not block
-ssl_mock_tcp:0:0:0
-
-Test mock non-blocking TCP connection: client would block
-ssl_mock_tcp:0:0xB509:0
-
-Test mock non-blocking TCP connection: server would block
-ssl_mock_tcp:0:0x0FB1:0
-
-Test mock non-blocking TCP connection: both peers would block
-ssl_mock_tcp:0:0x1111:0xEEEE
+Test mock non-blocking TCP connection
+ssl_mock_tcp:0
 
 Test mock blocking TCP connection (interleaving)
-ssl_mock_tcp_interleaving:1:0:0
+ssl_mock_tcp_interleaving:1
 
-Test mock non-blocking TCP connection: would not block (interleaving)
-ssl_mock_tcp_interleaving:0:0:0
+Test mock non-blocking TCP connection (interleaving)
+ssl_mock_tcp_interleaving:0
 
-Test mock non-blocking TCP connection: client would block (interleaving)
-ssl_mock_tcp_interleaving:0:0xB509:0
+Message queue - sanity
+ssl_message_queue_sanity:
 
-Test mock non-blocking TCP connection: server would block (interleaving)
-ssl_mock_tcp_interleaving:0:0x0FB1:0
+Message queue - basic test
+ssl_message_queue_basic:
 
-Test mock non-blocking TCP connection: both peers would block (interleaving)
-ssl_mock_tcp_interleaving:0:0x1111:0xEEEE
+Message queue - overflow/underflow
+ssl_message_queue_overflow_underflow:
+
+Message queue - interleaved
+ssl_message_queue_interleaved:
+
+Message queue - insufficient buffer
+ssl_message_queue_insufficient_buffer:
+
+Message transport mock - uninitialized structures
+ssl_message_mock_uninitialized:
+
+Message transport mock - basic test
+ssl_message_mock_basic:
+
+Message transport mock - queue overflow/underflow
+ssl_message_mock_queue_overflow_underflow:
+
+Message transport mock - socket overflow
+ssl_message_mock_socket_overflow:
+
+Message transport mock - truncated message
+ssl_message_mock_truncated:
+
+Message transport mock - socket read error
+ssl_message_mock_socket_read_error:
+
+Message transport mock - one-way interleaved sends/reads
+ssl_message_mock_interleaved_one_way:
+
+Message transport mock - two-way interleaved sends/reads
+ssl_message_mock_interleaved_two_ways:
+
+Test mbedtls_endpoint sanity for the client
+mbedtls_endpoint_sanity:MBEDTLS_SSL_IS_CLIENT
+
+Test mbedtls_endpoint sanity for the server
+mbedtls_endpoint_sanity:MBEDTLS_SSL_IS_SERVER
+
+Test moving clients handshake to state: HELLO_REQUEST
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_HELLO_REQUEST:1
+
+Test moving clients handshake to state: CLIENT_HELLO
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_CLIENT_HELLO:1
+
+Test moving clients handshake to state: SERVER_HELLO
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_SERVER_HELLO:1
+
+Test moving clients handshake to state: SERVER_CERTIFICATE
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_SERVER_CERTIFICATE:1
+
+Test moving clients handshake to state: SERVER_KEY_EXCHANGE
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_SERVER_KEY_EXCHANGE:1
+
+Test moving clients handshake to state: CERTIFICATE_REQUEST
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_CERTIFICATE_REQUEST:1
+
+Test moving clients handshake to state: SERVER_HELLO_DONE
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_SERVER_HELLO_DONE:1
+
+Test moving clients handshake to state: CLIENT_CERTIFICATE
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_CLIENT_CERTIFICATE:1
+
+Test moving clients handshake to state: CLIENT_KEY_EXCHANGE
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_CLIENT_KEY_EXCHANGE:1
+
+Test moving clients handshake to state: CERTIFICATE_VERIFY
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_CERTIFICATE_VERIFY:1
+
+Test moving clients handshake to state: CLIENT_CHANGE_CIPHER_SPEC
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC:1
+
+Test moving clients handshake to state: CLIENT_FINISHED
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_CLIENT_FINISHED:1
+
+Test moving clients handshake to state: SERVER_CHANGE_CIPHER_SPEC
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC:1
+
+Test moving clients handshake to state: SERVER_FINISHED
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_SERVER_FINISHED:1
+
+Test moving clients handshake to state: FLUSH_BUFFERS
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_FLUSH_BUFFERS:1
+
+Test moving clients handshake to state: HANDSHAKE_WRAPUP
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_HANDSHAKE_WRAPUP:1
+
+Test moving clients handshake to state: HANDSHAKE_OVER
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_HANDSHAKE_OVER:1
+
+Test moving servers handshake to state: HELLO_REQUEST
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_HELLO_REQUEST:1
+
+Test moving servers handshake to state: CLIENT_HELLO
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_CLIENT_HELLO:1
+
+Test moving servers handshake to state: SERVER_HELLO
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_SERVER_HELLO:1
+
+Test moving servers handshake to state: SERVER_CERTIFICATE
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_SERVER_CERTIFICATE:1
+
+Test moving servers handshake to state: SERVER_KEY_EXCHANGE
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_SERVER_KEY_EXCHANGE:1
+
+Test moving servers handshake to state: CERTIFICATE_REQUEST
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_CERTIFICATE_REQUEST:1
+
+Test moving servers handshake to state: SERVER_HELLO_DONE
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_SERVER_HELLO_DONE:1
+
+Test moving servers handshake to state: CLIENT_CERTIFICATE
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_CLIENT_CERTIFICATE:1
+
+Test moving servers handshake to state: CLIENT_KEY_EXCHANGE
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_CLIENT_KEY_EXCHANGE:1
+
+Test moving servers handshake to state: CERTIFICATE_VERIFY
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_CERTIFICATE_VERIFY:1
+
+Test moving servers handshake to state: CLIENT_CHANGE_CIPHER_SPEC
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC:1
+
+Test moving servers handshake to state: CLIENT_FINISHED
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_CLIENT_FINISHED:1
+
+Test moving servers handshake to state: SERVER_CHANGE_CIPHER_SPEC
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC:1
+
+Test moving servers handshake to state: SERVER_FINISHED
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_SERVER_FINISHED:1
+
+Test moving servers handshake to state: FLUSH_BUFFERS
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_FLUSH_BUFFERS:1
+
+Test moving servers handshake to state: HANDSHAKE_WRAPUP
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_HANDSHAKE_WRAPUP:1
+
+Test moving servers handshake to state: HANDSHAKE_OVER
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_HANDSHAKE_OVER:1
+
+Negative test moving clients ssl to state: VERIFY_REQUEST_SENT
+move_handshake_to_state:MBEDTLS_SSL_IS_CLIENT:MBEDTLS_SSL_SERVER_HELLO_VERIFY_REQUEST_SENT:0
+
+Negative test moving servers ssl to state: NEW_SESSION_TICKET
+move_handshake_to_state:MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_SERVER_NEW_SESSION_TICKET:0
 
 SSL DTLS replay: initial state, seqnum 0
 ssl_dtls_replay:"":"000000000000":0
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index a57e256..4fba1f1 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -1,7 +1,9 @@
 /* BEGIN_HEADER */
 #include <mbedtls/ssl.h>
 #include <mbedtls/ssl_internal.h>
-
+#include <mbedtls/ctr_drbg.h>
+#include <mbedtls/entropy.h>
+#include <mbedtls/certs.h>
 
 /*
  * Buffer structure for custom I/O callbacks.
@@ -59,7 +61,7 @@
  *          zero and \p input is NULL.
  */
 int mbedtls_test_buffer_put( mbedtls_test_buffer *buf,
-                             const unsigned char* input, size_t input_len )
+                             const unsigned char *input, size_t input_len )
 {
     size_t overflow = 0;
 
@@ -77,34 +79,47 @@
         return ( input_len == 0 ) ? 0 : -1;
     }
 
-    /* Calculate the number of bytes that need to be placed at lower memory
-     * address */
-    if( buf->start + buf->content_length + input_len
-        > buf->capacity )
+     /* Check if the buffer has not come full circle and free space is not in
+      * the middle */
+    if( buf->start + buf->content_length < buf->capacity )
     {
-        overflow = ( buf->start + buf->content_length + input_len )
-                    % buf->capacity;
+
+        /* Calculate the number of bytes that need to be placed at lower memory
+        * address */
+        if( buf->start + buf->content_length + input_len
+            > buf->capacity )
+        {
+            overflow = ( buf->start + buf->content_length + input_len )
+                        % buf->capacity;
+        }
+
+        memcpy( buf->buffer + buf->start + buf->content_length, input,
+                    input_len - overflow );
+        memcpy( buf->buffer, input + input_len - overflow, overflow );
+
+    }
+    else
+    {
+        /* The buffer has come full circle and free space is in the middle */
+        memcpy( buf->buffer + buf->start + buf->content_length - buf->capacity,
+                input, input_len );
     }
 
-    memcpy( buf->buffer + buf->start + buf->content_length, input,
-            input_len - overflow );
-    memcpy( buf->buffer, input + input_len - overflow, overflow );
     buf->content_length += input_len;
-
     return input_len;
 }
 
 /*
- * Gets \p output_len bytes from the \p output buffer into the ring buffer
- * \p buf.
+ * Gets \p output_len bytes from the ring buffer \p buf into the
+ * \p output buffer. The output buffer can be NULL, in this case a part of the
+ * ring buffer will be dropped, if the requested length is available.
  *
  * \p buf must have been initialized and set up by calling
  * `mbedtls_test_buffer_init()` and `mbedtls_test_buffer_setup()`.
  *
  * \retval  \p output_len, if the data is available.
  * \retval  0 <= value < \p output_len, if the data is not available.
- * \retval  -1, if \buf is NULL, it hasn't been set up or \p output_len is not
- *          zero and \p output is NULL
+ * \retval  -1, if \buf is NULL or it hasn't been set up.
  */
 int mbedtls_test_buffer_get( mbedtls_test_buffer *buf,
                              unsigned char* output, size_t output_len )
@@ -114,10 +129,8 @@
     if( ( buf == NULL ) || ( buf->buffer == NULL ) )
         return -1;
 
-    if( output == NULL )
-    {
-        return ( output_len == 0 ) ? 0 : -1;
-    }
+    if( output == NULL && output_len == 0 )
+        return 0;
 
     if( buf->content_length < output_len )
         output_len = buf->content_length;
@@ -129,8 +142,12 @@
         overflow = ( buf->start + output_len ) % buf->capacity;
     }
 
-    memcpy( output, buf->buffer + buf->start, output_len - overflow );
-    memcpy( output + output_len - overflow, buf->buffer, overflow );
+    if( output != NULL )
+    {
+        memcpy( output, buf->buffer + buf->start, output_len - overflow );
+        memcpy( output + output_len - overflow, buf->buffer, overflow );
+    }
+
     buf->content_length -= output_len;
     buf->start = ( buf->start + output_len ) % buf->capacity;
 
@@ -138,6 +155,136 @@
 }
 
 /*
+ * Errors used in the message transport mock tests
+ */
+ #define MBEDTLS_TEST_ERROR_ARG_NULL -11
+ #define MBEDTLS_TEST_ERROR_QUEUE_FULL -22
+ #define MBEDTLS_TEST_ERROR_QUEUE_EMPTY -33
+ #define MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED -44
+
+/*
+ * Context for a message metadata queue (fifo) that is on top of the ring buffer.
+ */
+typedef struct mbedtls_test_message_queue
+{
+    size_t *messages;
+    int pos;
+    int num;
+    int capacity;
+} mbedtls_test_message_queue;
+
+/*
+ * Setup and free functions for the message metadata queue.
+ *
+ * \p capacity describes the number of message metadata chunks that can be held
+ *    within the queue.
+ *
+ * \retval  0, if a metadata queue of a given length can be allocated.
+ * \retval  MBEDTLS_ERR_SSL_ALLOC_FAILED, if allocation failed.
+ */
+int mbedtls_test_message_queue_setup( mbedtls_test_message_queue *queue,
+                                      size_t capacity )
+{
+    queue->messages = (size_t*) mbedtls_calloc( capacity, sizeof(size_t) );
+    if( NULL == queue->messages )
+        return MBEDTLS_ERR_SSL_ALLOC_FAILED;
+
+    queue->capacity = capacity;
+    queue->pos = 0;
+    queue->num = 0;
+
+    return 0;
+}
+
+void mbedtls_test_message_queue_free( mbedtls_test_message_queue *queue )
+{
+    if( queue == NULL )
+        return;
+
+    if( queue->messages != NULL )
+        mbedtls_free( queue->messages );
+
+    memset( queue, 0, sizeof( *queue ) );
+}
+
+/*
+ * Push message length information onto the message metadata queue.
+ * This will become the last element to leave it (fifo).
+ *
+ * \retval  MBEDTLS_TEST_ERROR_ARG_NULL, if the queue is null.
+ * \retval  MBEDTLS_TEST_ERROR_QUEUE_FULL, if the queue is full.
+ * \retval  \p len, if the push was successful.
+ */
+int mbedtls_test_message_queue_push_info( mbedtls_test_message_queue *queue,
+                                          size_t len )
+{
+    int place;
+    if( queue == NULL )
+        return MBEDTLS_TEST_ERROR_ARG_NULL;
+
+    if( queue->num >= queue->capacity )
+        return MBEDTLS_TEST_ERROR_QUEUE_FULL;
+
+    place = ( queue->pos + queue->num ) % queue->capacity;
+    queue->messages[place] = len;
+    queue->num++;
+    return len;
+}
+
+/*
+ * Pop information about the next message length from the queue. This will be
+ * the oldest inserted message length(fifo). \p msg_len can be null, in which
+ * case the data will be popped from the queue but not copied anywhere.
+ *
+ * \retval  MBEDTLS_TEST_ERROR_ARG_NULL, if the queue is null.
+ * \retval  MBEDTLS_TEST_ERROR_QUEUE_EMPTY, if the queue is empty.
+ * \retval  message length, if the pop was successful, up to the given
+            \p buf_len.
+ */
+int mbedtls_test_message_queue_pop_info( mbedtls_test_message_queue *queue,
+                                         size_t buf_len )
+{
+    size_t message_length;
+    if( queue == NULL )
+        return MBEDTLS_TEST_ERROR_ARG_NULL;
+    if( queue->num == 0 )
+        return MBEDTLS_TEST_ERROR_QUEUE_EMPTY;
+
+    message_length = queue->messages[queue->pos];
+    queue->messages[queue->pos] = 0;
+    queue->num--;
+    queue->pos++;
+    queue->pos %= queue->capacity;
+    if( queue->pos < 0 )
+        queue->pos += queue->capacity;
+
+    return ( message_length > buf_len ) ? buf_len : message_length;
+}
+
+/*
+ * Take a peek on the info about the next message length from the queue.
+ * This will be the oldest inserted message length(fifo).
+ *
+ * \retval  MBEDTLS_TEST_ERROR_ARG_NULL, if the queue is null.
+ * \retval  MBEDTLS_TEST_ERROR_QUEUE_EMPTY, if the queue is empty.
+ * \retval  0, if the peek was successful.
+ * \retval  MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED, if the given buffer length is
+ *          too small to fit the message. In this case the \p msg_len will be
+ *          set to the full message length so that the
+ *          caller knows what portion of the message can be dropped.
+ */
+int mbedtls_test_message_queue_peek_info( mbedtls_test_message_queue *queue,
+                                          size_t buf_len, size_t* msg_len )
+{
+    if( queue == NULL || msg_len == NULL )
+        return MBEDTLS_TEST_ERROR_ARG_NULL;
+    if( queue->num == 0 )
+        return MBEDTLS_TEST_ERROR_QUEUE_EMPTY;
+
+    *msg_len = queue->messages[queue->pos];
+    return ( *msg_len > buf_len ) ? MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED : 0;
+}
+/*
  * Context for the I/O callbacks simulating network connection.
  */
 
@@ -146,7 +293,6 @@
 typedef struct mbedtls_mock_socket
 {
     int status;
-    uint32_t blocking_pattern;
     mbedtls_test_buffer *input;
     mbedtls_test_buffer *output;
     struct mbedtls_mock_socket *peer;
@@ -212,20 +358,7 @@
 {
     int ret = -1;
 
-    peer1->input = peer2->output =
-        (mbedtls_test_buffer*) mbedtls_calloc( 1, sizeof(mbedtls_test_buffer) );
-    if( peer1->input == NULL )
-    {
-        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
-        goto exit;
-    }
-    mbedtls_test_buffer_init( peer1->input );
-    if( 0 != ( ret = mbedtls_test_buffer_setup( peer1->input, bufsize ) ) )
-    {
-        goto exit;
-    }
-
-    peer1->output = peer2->input =
+    peer1->output =
         (mbedtls_test_buffer*) mbedtls_calloc( 1, sizeof(mbedtls_test_buffer) );
     if( peer1->output == NULL )
     {
@@ -238,8 +371,23 @@
         goto exit;
     }
 
+    peer2->output =
+        (mbedtls_test_buffer*) mbedtls_calloc( 1, sizeof(mbedtls_test_buffer) );
+    if( peer2->output == NULL )
+    {
+        ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+        goto exit;
+    }
+    mbedtls_test_buffer_init( peer2->output );
+    if( 0 != ( ret = mbedtls_test_buffer_setup( peer2->output, bufsize ) ) )
+    {
+        goto exit;
+    }
+
     peer1->peer = peer2;
     peer2->peer = peer1;
+    peer1->input = peer2->output;
+    peer2->input = peer1->output;
 
     peer1->status = peer2->status = MBEDTLS_MOCK_SOCKET_CONNECTED;
     ret = 0;
@@ -256,26 +404,6 @@
 }
 
 /*
- * Set the blocking pattern for the socket.
- *
- * For every bit of \p blocking_pattern set to one the socket will simulate a
- * "would block" event. The bits are processed starting with the least
- * significant bit and every call to a non-blocking I/O function consumes one.
- *
- * The behaviour of blocking I/O functions remains unchanged.
- */
-int mbedtls_mock_socket_set_block( mbedtls_mock_socket* socket,
-                                   uint32_t blocking_pattern )
-{
-    if( socket == NULL )
-        return -1;
-
-    socket->blocking_pattern = blocking_pattern;
-
-    return 0;
-}
-
-/*
  * Callbacks for simulating blocking I/O over connection-oriented transport.
  */
 
@@ -310,14 +438,11 @@
     if( socket == NULL || socket->status != MBEDTLS_MOCK_SOCKET_CONNECTED )
         return -1;
 
-    if( socket->blocking_pattern & 1 )
+    if( socket->output->capacity == socket->output->content_length )
     {
-        socket->blocking_pattern >>= 1;
         return MBEDTLS_ERR_SSL_WANT_WRITE;
     }
 
-    socket->blocking_pattern >>= 1;
-
     return mbedtls_test_buffer_put( socket->output, buf, len );
 }
 
@@ -328,17 +453,438 @@
     if( socket == NULL || socket->status != MBEDTLS_MOCK_SOCKET_CONNECTED )
         return -1;
 
-    if( socket->blocking_pattern & 1 )
+    if( socket->input->content_length == 0)
     {
-        socket->blocking_pattern >>= 1;
         return MBEDTLS_ERR_SSL_WANT_READ;
     }
 
-    socket->blocking_pattern >>= 1;
-
     return mbedtls_test_buffer_get( socket->input, buf, len );
 }
 
+/* Errors used in the message socket mocks */
+
+#define MBEDTLS_TEST_ERROR_CONTEXT_ERROR -55
+#define MBEDTLS_TEST_ERROR_SEND_FAILED -66
+#define MBEDTLS_TEST_ERROR_RECV_FAILED -77
+
+/*
+ * Structure used as an addon, or a wrapper, around the mocked sockets.
+ * Contains an input queue, to which the other socket pushes metadata,
+ * and an output queue, to which this one pushes metadata. This context is
+ * considered as an owner of the input queue only, which is initialized and
+ * freed in the respective setup and free calls.
+ */
+typedef struct mbedtls_test_message_socket_context
+{
+    mbedtls_test_message_queue* queue_input;
+    mbedtls_test_message_queue* queue_output;
+    mbedtls_mock_socket* socket;
+} mbedtls_test_message_socket_context;
+
+/*
+ * Setup a given mesasge socket context including initialization of
+ * input/output queues to a chosen capacity of messages. Also set the
+ * corresponding mock socket.
+ *
+ * \retval  0, if everything succeeds.
+ * \retval  MBEDTLS_ERR_SSL_ALLOC_FAILED, if allocation of a message
+ *          queue failed.
+ */
+int mbedtls_message_socket_setup( mbedtls_test_message_queue* queue_input,
+                                  mbedtls_test_message_queue* queue_output,
+                                  size_t queue_capacity,
+                                  mbedtls_mock_socket* socket,
+                                  mbedtls_test_message_socket_context* ctx )
+{
+    int ret = mbedtls_test_message_queue_setup( queue_input, queue_capacity );
+    if( ret != 0 )
+        return ret;
+    ctx->queue_input = queue_input;
+    ctx->queue_output = queue_output;
+    ctx->socket = socket;
+    mbedtls_mock_socket_init( socket );
+
+    return 0;
+}
+
+/*
+ * Close a given message socket context, along with the socket itself. Free the
+ * memory allocated by the input queue.
+ */
+void mbedtls_message_socket_close( mbedtls_test_message_socket_context* ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    mbedtls_test_message_queue_free( ctx->queue_input );
+    mbedtls_mock_socket_close( ctx->socket );
+    memset( ctx, 0, sizeof( *ctx ) );
+}
+
+/*
+ * Send one message through a given message socket context.
+ *
+ * \retval  \p len, if everything succeeds.
+ * \retval  MBEDTLS_TEST_ERROR_CONTEXT_ERROR, if any of the needed context
+ *          elements or the context itself is null.
+ * \retval  MBEDTLS_TEST_ERROR_SEND_FAILED if mbedtls_mock_tcp_send_b failed.
+ * \retval  MBEDTLS_TEST_ERROR_QUEUE_FULL, if the output queue is full.
+ *
+ * This function will also return any error from
+ * mbedtls_test_message_queue_push_info.
+ */
+int mbedtls_mock_tcp_send_msg( void *ctx, const unsigned char *buf, size_t len )
+{
+    mbedtls_test_message_queue* queue;
+    mbedtls_mock_socket* socket;
+    mbedtls_test_message_socket_context *context = (mbedtls_test_message_socket_context*) ctx;
+
+    if( context == NULL || context->socket == NULL
+        || context->queue_output == NULL )
+    {
+        return MBEDTLS_TEST_ERROR_CONTEXT_ERROR;
+    }
+
+    queue = context->queue_output;
+    socket = context->socket;
+
+    if( queue->num >= queue->capacity )
+        return MBEDTLS_TEST_ERROR_QUEUE_FULL;
+
+    if( mbedtls_mock_tcp_send_b( socket, buf, len ) != (int) len )
+        return MBEDTLS_TEST_ERROR_SEND_FAILED;
+
+    return mbedtls_test_message_queue_push_info( queue, len );
+}
+
+/*
+ * Receive one message from a given message socket context and return message
+ * length or an error.
+ *
+ * \retval  message length, if everything succeeds.
+ * \retval  MBEDTLS_TEST_ERROR_CONTEXT_ERROR, if any of the needed context
+ *          elements or the context itself is null.
+ * \retval  MBEDTLS_TEST_ERROR_RECV_FAILED if mbedtls_mock_tcp_recv_b failed.
+ *
+ * This function will also return any error other than
+ * MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED from mbedtls_test_message_queue_peek_info.
+ */
+int mbedtls_mock_tcp_recv_msg( void *ctx, unsigned char *buf, size_t buf_len )
+{
+    mbedtls_test_message_queue* queue;
+    mbedtls_mock_socket* socket;
+    mbedtls_test_message_socket_context *context = (mbedtls_test_message_socket_context*) ctx;
+    size_t drop_len;
+    size_t msg_len;
+    int ret;
+
+    if( context == NULL || context->socket == NULL
+        || context->queue_input == NULL )
+    {
+        return MBEDTLS_TEST_ERROR_CONTEXT_ERROR;
+    }
+
+    queue = context->queue_input;
+    socket = context->socket;
+
+    /* Peek first, so that in case of a socket error the data remains in
+     * the queue. */
+    ret = mbedtls_test_message_queue_peek_info( queue, buf_len, &msg_len );
+    if( ret == MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED )
+    {
+        /* Calculate how much to drop */
+        drop_len = msg_len - buf_len;
+
+        /* Set the requested message len to be buffer length */
+        msg_len = buf_len;
+    } else if( ret != 0 )
+    {
+        return ret;
+    }
+
+    if( mbedtls_mock_tcp_recv_b( socket, buf, msg_len ) != (int) msg_len )
+        return MBEDTLS_TEST_ERROR_RECV_FAILED;
+
+    if( ret == MBEDTLS_TEST_ERROR_MESSAGE_TRUNCATED )
+    {
+        /* Drop the remaining part of the message */
+        if( mbedtls_mock_tcp_recv_b( socket, NULL, drop_len ) != (int) drop_len )
+        {
+          /* Inconsistent state - part of the message was read,
+           * and a part couldn't. Not much we can do here, but it should not
+           * happen in test environment, unless forced manually. */
+        }
+    }
+    mbedtls_test_message_queue_pop_info( queue, buf_len );
+
+    return msg_len;
+}
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+
+/*
+ * Structure with endpoint's certificates for SSL communication tests.
+ */
+typedef struct mbedtls_endpoint_certificate
+{
+    mbedtls_x509_crt ca_cert;
+    mbedtls_x509_crt cert;
+    mbedtls_x509_crt cert2;
+    mbedtls_pk_context pkey;
+    mbedtls_pk_context pkey2;
+} mbedtls_endpoint_certificate;
+
+/*
+ * Endpoint structure for SSL communication tests.
+ */
+typedef struct mbedtls_endpoint
+{
+    const char *name;
+    mbedtls_ssl_context ssl;
+    mbedtls_ssl_config conf;
+    mbedtls_ctr_drbg_context ctr_drbg;
+    mbedtls_entropy_context entropy;
+    mbedtls_mock_socket socket;
+    mbedtls_endpoint_certificate cert;
+} mbedtls_endpoint;
+
+/*
+ * Initializes \p ep_cert structure and assigns it to endpoint
+ * represented by \p ep.
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int mbedtls_endpoint_certificate_init( mbedtls_endpoint *ep )
+{
+    int i = 0;
+    int ret = -1;
+    mbedtls_endpoint_certificate *cert;
+
+    if( ep == NULL )
+    {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+    }
+
+    cert = &( ep->cert );
+    mbedtls_x509_crt_init( &( cert->ca_cert ) );
+    mbedtls_x509_crt_init( &( cert->cert ) );
+    mbedtls_x509_crt_init( &( cert->cert2 ) );
+    mbedtls_pk_init( &( cert->pkey ) );
+    mbedtls_pk_init( &( cert->pkey2 ) );
+
+    /* Load the trusted CA */
+
+    for( i = 0; mbedtls_test_cas[i] != NULL; i++ )
+    {
+        ret = mbedtls_x509_crt_parse( &( cert->ca_cert ),
+                        (const unsigned char *) mbedtls_test_cas[i],
+                        mbedtls_test_cas_len[i] );
+        TEST_ASSERT( ret == 0 );
+    }
+
+    for( i = 0; mbedtls_test_cas_der[i] != NULL; i++ )
+    {
+        ret = mbedtls_x509_crt_parse_der( &( cert->ca_cert ),
+                        (const unsigned char *) mbedtls_test_cas_der[i],
+                        mbedtls_test_cas_der_len[i] );
+        TEST_ASSERT( ret == 0 );
+    }
+
+    /* Load own certificate and private key */
+
+    if( ep->conf.endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        ret = mbedtls_x509_crt_parse( &( cert->cert ),
+                            (const unsigned char *) mbedtls_test_srv_crt_rsa,
+                            mbedtls_test_srv_crt_rsa_len );
+        TEST_ASSERT( ret == 0 );
+
+        ret = mbedtls_pk_parse_key( &( cert->pkey ),
+                            (const unsigned char *) mbedtls_test_srv_key_rsa,
+                            mbedtls_test_srv_key_rsa_len, NULL, 0 );
+        TEST_ASSERT( ret == 0 );
+
+        ret = mbedtls_x509_crt_parse( &( cert->cert2 ),
+                            (const unsigned char *) mbedtls_test_srv_crt_ec,
+                            mbedtls_test_srv_crt_ec_len );
+        TEST_ASSERT( ret == 0 );
+
+        ret = mbedtls_pk_parse_key( &( cert->pkey2 ),
+                            (const unsigned char *) mbedtls_test_srv_key_ec,
+                            mbedtls_test_srv_key_ec_len, NULL, 0 );
+        TEST_ASSERT( ret == 0 );
+    }
+    else
+    {
+        ret = mbedtls_x509_crt_parse( &( cert->cert ),
+                            (const unsigned char *) mbedtls_test_cli_crt,
+                            mbedtls_test_cli_crt_len );
+        TEST_ASSERT( ret == 0 );
+
+        ret = mbedtls_pk_parse_key( &( cert->pkey ),
+                            (const unsigned char *) mbedtls_test_cli_key,
+                            mbedtls_test_cli_key_len, NULL, 0 );
+        TEST_ASSERT( ret == 0 );
+    }
+
+    mbedtls_ssl_conf_ca_chain( &( ep->conf ), &( cert->ca_cert ), NULL );
+
+    ret = mbedtls_ssl_conf_own_cert( &( ep->conf ), &( cert->cert ), &( cert->pkey ) );
+    TEST_ASSERT( ret == 0 );
+
+    if( ep->conf.endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        ret = mbedtls_ssl_conf_own_cert( &( ep->conf ), &( cert->cert2 ), &( cert->pkey2 ) );
+        TEST_ASSERT( ret == 0 );
+    }
+
+exit:
+    if( ret != 0 )
+    {
+        mbedtls_x509_crt_free( &( cert->ca_cert ) );
+        mbedtls_x509_crt_free( &( cert->cert ) );
+        mbedtls_x509_crt_free( &( cert->cert2 ) );
+        mbedtls_pk_free( &( cert->pkey ) );
+        mbedtls_pk_free( &( cert->pkey2 ) );
+    }
+
+    return ret;
+}
+
+/*
+ * Initializes \p ep structure. It is important to call `mbedtls_endpoint_free()`
+ * after calling this function even if it fails.
+ *
+ * \p endpoint_type must be set as MBEDTLS_SSL_IS_SERVER or
+ * MBEDTLS_SSL_IS_CLIENT.
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int mbedtls_endpoint_init( mbedtls_endpoint *ep, int endpoint_type )
+{
+    int ret = -1;
+
+    if( ep == NULL )
+    {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+    }
+
+    memset( ep, 0, sizeof( *ep ) );
+
+    ep->name = ( endpoint_type == MBEDTLS_SSL_IS_SERVER ) ? "Server" : "Client";
+
+    mbedtls_ssl_init( &( ep->ssl ) );
+    mbedtls_ssl_config_init( &( ep->conf ) );
+    mbedtls_ctr_drbg_init( &( ep->ctr_drbg ) );
+    mbedtls_ssl_conf_rng( &( ep->conf ),
+        mbedtls_ctr_drbg_random,
+        &( ep->ctr_drbg ) );
+    mbedtls_entropy_init( &( ep->entropy ) );
+    mbedtls_mock_socket_init( &( ep->socket ) );
+
+    ret = mbedtls_ctr_drbg_seed( &( ep->ctr_drbg ), mbedtls_entropy_func,
+                    &( ep->entropy ), (const unsigned char *) ( ep->name ),
+                    strlen( ep->name ) );
+    TEST_ASSERT( ret == 0 );
+
+    /* Non-blocking callbacks without timeout */
+    mbedtls_ssl_set_bio( &( ep->ssl ), &( ep->socket ),
+        mbedtls_mock_tcp_send_nb,
+        mbedtls_mock_tcp_recv_nb,
+        NULL );
+
+    ret = mbedtls_ssl_setup( &( ep->ssl ), &( ep->conf ) );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_ssl_config_defaults( &( ep->conf ), endpoint_type,
+                                        MBEDTLS_SSL_TRANSPORT_STREAM,
+                                        MBEDTLS_SSL_PRESET_DEFAULT );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_endpoint_certificate_init( ep );
+    TEST_ASSERT( ret == 0 );
+
+exit:
+    return ret;
+}
+
+/*
+ * Deinitializes certificates from endpoint represented by \p ep.
+ */
+void mbedtls_endpoint_certificate_free( mbedtls_endpoint *ep )
+{
+    mbedtls_endpoint_certificate *cert = &( ep->cert );
+    mbedtls_x509_crt_free( &( cert->ca_cert ) );
+    mbedtls_x509_crt_free( &( cert->cert ) );
+    mbedtls_x509_crt_free( &( cert->cert2 ) );
+    mbedtls_pk_free( &( cert->pkey ) );
+    mbedtls_pk_free( &( cert->pkey2 ) );
+}
+
+/*
+ * Deinitializes endpoint represented by \p ep.
+ */
+void mbedtls_endpoint_free( mbedtls_endpoint *ep )
+{
+    mbedtls_endpoint_certificate_free( ep );
+
+    mbedtls_ssl_free( &( ep->ssl ) );
+    mbedtls_ssl_config_free( &( ep->conf ) );
+    mbedtls_ctr_drbg_free( &( ep->ctr_drbg ) );
+    mbedtls_entropy_free( &( ep->entropy ) );
+    mbedtls_mock_socket_close( &( ep->socket ) );
+}
+
+/*
+ * This function moves ssl handshake from \p ssl to prescribed \p state.
+ * /p second_ssl is used as second endpoint and their sockets have to be
+ * connected before calling this function.
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int mbedtls_move_handshake_to_state( mbedtls_ssl_context *ssl,
+                                     mbedtls_ssl_context *second_ssl,
+                                     int state )
+{
+    enum { BUFFSIZE = 1024 };
+    int max_steps = 1000;
+    int ret = 0;
+
+    if( ssl == NULL || second_ssl == NULL )
+    {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+    }
+
+    /* Perform communication via connected sockets */
+    while( ( ssl->state != state ) && ( --max_steps >= 0 ) )
+    {
+        /* If /p second_ssl ends the handshake procedure before /p ssl then
+         * there is no need to call the next step */
+        if( second_ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+        {
+            ret = mbedtls_ssl_handshake_step( second_ssl );
+            if( ret != 0 && ret != MBEDTLS_ERR_SSL_WANT_READ &&
+                            ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+            {
+                return ret;
+            }
+        }
+
+        /* We only care about the \p ssl state and returns, so we call it last,
+         * to leave the iteration as soon as the state is as expected. */
+        ret = mbedtls_ssl_handshake_step( ssl );
+        if( ret != 0 && ret != MBEDTLS_ERR_SSL_WANT_READ &&
+                        ret != MBEDTLS_ERR_SSL_WANT_WRITE )
+        {
+            return ret;
+        }
+    }
+
+    return ( max_steps >= 0 ) ? ret : -1;
+}
+
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
+
 /*
  * Helper function setting up inverse record transformations
  * using given cipher, hash, EtM mode, authentication tag length,
@@ -714,8 +1260,7 @@
     TEST_ASSERT( mbedtls_test_buffer_get( NULL, output, sizeof( output ) )
                     == -1 );
     TEST_ASSERT( mbedtls_test_buffer_put( NULL, NULL, sizeof( input ) ) == -1 );
-    TEST_ASSERT( mbedtls_test_buffer_get( NULL, NULL, sizeof( output ) )
-                    == -1 );
+
     TEST_ASSERT( mbedtls_test_buffer_put( NULL, NULL, 0 ) == -1 );
     TEST_ASSERT( mbedtls_test_buffer_get( NULL, NULL, 0 ) == -1 );
 
@@ -727,22 +1272,33 @@
     TEST_ASSERT( mbedtls_test_buffer_get( &buf, output, sizeof( output ) )
                     == -1 );
     TEST_ASSERT( mbedtls_test_buffer_put( &buf, NULL, sizeof( input ) ) == -1 );
-    TEST_ASSERT( mbedtls_test_buffer_get( &buf, NULL, sizeof( output ) )
-                    == -1 );
+
     TEST_ASSERT( mbedtls_test_buffer_put( &buf, NULL, 0 ) == -1 );
     TEST_ASSERT( mbedtls_test_buffer_get( &buf, NULL, 0 ) == -1 );
 
-    /* Make sure calling put end get on NULL input and output only results in
-     * error if the length is not zero. */
+    /* Make sure calling put and get on NULL input only results in
+     * error if the length is not zero, and that a NULL output is valid for data
+     * dropping.
+     */
 
     TEST_ASSERT( mbedtls_test_buffer_setup( &buf, sizeof( input ) ) == 0 );
 
     TEST_ASSERT( mbedtls_test_buffer_put( &buf, NULL, sizeof( input ) ) == -1 );
     TEST_ASSERT( mbedtls_test_buffer_get( &buf, NULL, sizeof( output ) )
-                    == -1 );
+                    == 0 );
     TEST_ASSERT( mbedtls_test_buffer_put( &buf, NULL, 0 ) == 0 );
     TEST_ASSERT( mbedtls_test_buffer_get( &buf, NULL, 0 ) == 0 );
 
+    /* Make sure calling put several times in the row is safe */
+
+    TEST_ASSERT( mbedtls_test_buffer_put( &buf, input, sizeof( input ) )
+                                          == sizeof( input ) );
+    TEST_ASSERT( mbedtls_test_buffer_get( &buf, output, 2 ) == 2 );
+    TEST_ASSERT( mbedtls_test_buffer_put( &buf, input, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_buffer_put( &buf, input, 2 ) == 1 );
+    TEST_ASSERT( mbedtls_test_buffer_put( &buf, input, 2 ) == 0 );
+
+
 exit:
 
     mbedtls_test_buffer_free( &buf );
@@ -905,9 +1461,10 @@
  */
 
 /* BEGIN_CASE */
-void ssl_mock_tcp( int blocking, int client_pattern, int server_pattern )
+void ssl_mock_tcp( int blocking )
 {
     enum { MSGLEN = 105 };
+    enum { BUFLEN = MSGLEN / 5 };
     unsigned char message[MSGLEN];
     unsigned char received[MSGLEN];
     mbedtls_mock_socket client;
@@ -916,8 +1473,6 @@
     int send_ret, recv_ret;
     mbedtls_ssl_send_t *send;
     mbedtls_ssl_recv_t *recv;
-    uint32_t client_block = client_pattern;
-    uint32_t server_block = server_pattern;
     unsigned i;
 
     if( blocking == 0 )
@@ -942,10 +1497,7 @@
     }
 
     /* Make sure that sending a message takes a few  iterations. */
-    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
-                                                   MSGLEN / 5 ) );
-    TEST_ASSERT( 0 == mbedtls_mock_socket_set_block( &client, client_block ) );
-    TEST_ASSERT( 0 == mbedtls_mock_socket_set_block( &server, server_block ) );
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server, BUFLEN ) );
 
     /* Send the message to the server */
     send_ret = recv_ret = 1;
@@ -954,28 +1506,56 @@
     {
         send_ret = send( &client, message + written, MSGLEN - written );
 
-        if( ( blocking == 0 ) && ( client_block & 1 ) )
+        TEST_ASSERT( send_ret >= 0 );
+        TEST_ASSERT( send_ret <= BUFLEN );
+        written += send_ret;
+
+        /* If the buffer is full we can test blocking and non-blocking send */
+        if ( send_ret == BUFLEN )
         {
-            TEST_ASSERT( send_ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+            int blocking_ret = send( &client, message , 1 );
+            if ( blocking )
+            {
+                TEST_ASSERT( blocking_ret == 0 );
+            }
+            else
+            {
+                TEST_ASSERT( blocking_ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+            }
         }
-        else
-        {
-            TEST_ASSERT( send_ret >= 0 );
-            written += send_ret;
-        }
-        client_block >>= 1;
 
         recv_ret = recv( &server, received + read, MSGLEN - read );
-        if( ( blocking == 0 ) && ( server_block & 1 ) )
+
+        /* The result depends on whether any data was sent */
+        if ( send_ret > 0 )
         {
-            TEST_ASSERT( recv_ret == MBEDTLS_ERR_SSL_WANT_READ );
+            TEST_ASSERT( recv_ret > 0 );
+            TEST_ASSERT( recv_ret <= BUFLEN );
+            read += recv_ret;
+        }
+        else if( blocking )
+        {
+            TEST_ASSERT( recv_ret == 0 );
         }
         else
         {
-            TEST_ASSERT( recv_ret >= 0 );
-            read += recv_ret;
+            TEST_ASSERT( recv_ret == MBEDTLS_ERR_SSL_WANT_READ );
+            recv_ret = 0;
         }
-        server_block >>= 1;
+
+        /* If the buffer is empty we can test blocking and non-blocking read */
+        if ( recv_ret == BUFLEN )
+        {
+            int blocking_ret = recv( &server, received, 1 );
+            if ( blocking )
+            {
+                TEST_ASSERT( blocking_ret == 0 );
+            }
+            else
+            {
+                TEST_ASSERT( blocking_ret == MBEDTLS_ERR_SSL_WANT_READ );
+            }
+        }
     }
     TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
 
@@ -993,11 +1573,11 @@
  */
 
 /* BEGIN_CASE */
-void ssl_mock_tcp_interleaving( int blocking,
-                                int client_pattern, int server_pattern )
+void ssl_mock_tcp_interleaving( int blocking )
 {
     enum { ROUNDS = 2 };
     enum { MSGLEN = 105 };
+    enum { BUFLEN = MSGLEN / 5 };
     unsigned char message[ROUNDS][MSGLEN];
     unsigned char received[ROUNDS][MSGLEN];
     mbedtls_mock_socket client;
@@ -1009,8 +1589,6 @@
     unsigned i, j, progress;
     mbedtls_ssl_send_t *send;
     mbedtls_ssl_recv_t *recv;
-    uint32_t client_block = client_pattern;
-    uint32_t server_block = server_pattern;
 
     if( blocking == 0 )
     {
@@ -1037,10 +1615,7 @@
     }
 
     /* Make sure that sending a message takes a few  iterations. */
-    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
-                                                   MSGLEN / 5 ) );
-    TEST_ASSERT( 0 == mbedtls_mock_socket_set_block( &client, client_block ) );
-    TEST_ASSERT( 0 == mbedtls_mock_socket_set_block( &server, server_block ) );
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server, BUFLEN ) );
 
     /* Send the message from both sides, interleaving. */
     progress = 1;
@@ -1053,72 +1628,80 @@
      * of at least one byte on either side. */
     while( progress != 0 )
     {
-        send_ret[0] = send( &client, message[0] + written[0],
-                                               MSGLEN - written[0] );
-        if( ( blocking == 0 ) && ( client_block & 1 ) )
-        {
-            TEST_ASSERT( send_ret[0] == MBEDTLS_ERR_SSL_WANT_WRITE );
-        }
-        else
-        {
-            TEST_ASSERT( send_ret[0] >= 0 );
-            written[0] += send_ret[0];
-        }
-        client_block >>= 1;
+        mbedtls_mock_socket *socket;
 
-        send_ret[1] = send( &server, message[1] + written[1],
-                                               MSGLEN - written[1] );
-        if( ( blocking == 0 ) && ( server_block & 1 ) )
+        for( i = 0; i < ROUNDS; i++ )
         {
-            TEST_ASSERT( send_ret[1] == MBEDTLS_ERR_SSL_WANT_WRITE );
-        }
-        else
-        {
-            TEST_ASSERT( send_ret[1] >= 0 );
-            written[1] += send_ret[1];
-        }
-        server_block >>= 1;
+            /* First sending is from the client */
+            socket = ( i % 2 == 0 ) ? ( &client ) : ( &server );
 
-        recv_ret[0] = recv( &server, received[0] + read[0],
-                                               MSGLEN - read[0] );
-        if( ( blocking == 0 ) && ( server_block & 1 ) )
-        {
-            TEST_ASSERT( recv_ret[0] == MBEDTLS_ERR_SSL_WANT_READ );
-        }
-        else
-        {
-            TEST_ASSERT( recv_ret[0] >= 0 );
-            read[0] += recv_ret[0];
-        }
-        server_block >>= 1;
+            send_ret[i] = send( socket, message[i] + written[i],
+                                               MSGLEN - written[i] );
+            TEST_ASSERT( send_ret[i] >= 0 );
+            TEST_ASSERT( send_ret[i] <= BUFLEN );
+            written[i] += send_ret[i];
 
-        recv_ret[1] = recv( &client, received[1] + read[1],
-                                               MSGLEN - read[1] );
-        if( ( blocking == 0 ) && ( client_block & 1 ) )
-        {
-            TEST_ASSERT( recv_ret[1] == MBEDTLS_ERR_SSL_WANT_READ );
+            /* If the buffer is full we can test blocking and non-blocking
+             * send */
+            if ( send_ret[i] == BUFLEN )
+            {
+                int blocking_ret = send( socket, message[i] , 1 );
+                if ( blocking )
+                {
+                    TEST_ASSERT( blocking_ret == 0 );
+                }
+                else
+                {
+                    TEST_ASSERT( blocking_ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+                }
+            }
         }
-        else
+
+        for( i = 0; i < ROUNDS; i++ )
         {
-            TEST_ASSERT( recv_ret[1] >= 0 );
-            read[1] += recv_ret[1];
+            /* First receiving is from the server */
+            socket = ( i % 2 == 0 ) ? ( &server ) : ( &client );
+
+            recv_ret[i] = recv( socket, received[i] + read[i],
+                                               MSGLEN - read[i] );
+
+            /* The result depends on whether any data was sent */
+            if ( send_ret[i] > 0 )
+            {
+                TEST_ASSERT( recv_ret[i] > 0 );
+                TEST_ASSERT( recv_ret[i] <= BUFLEN );
+                read[i] += recv_ret[i];
+            }
+            else if( blocking )
+            {
+                TEST_ASSERT( recv_ret[i] == 0 );
+            }
+            else
+            {
+                TEST_ASSERT( recv_ret[i] == MBEDTLS_ERR_SSL_WANT_READ );
+                recv_ret[i] = 0;
+            }
+
+            /* If the buffer is empty we can test blocking and non-blocking
+             * read */
+            if ( recv_ret[i] == BUFLEN )
+            {
+                int blocking_ret = recv( socket, received[i], 1 );
+                if ( blocking )
+                {
+                    TEST_ASSERT( blocking_ret == 0 );
+                }
+                else
+                {
+                    TEST_ASSERT( blocking_ret == MBEDTLS_ERR_SSL_WANT_READ );
+                }
+            }
         }
-        client_block >>= 1;
 
         progress = 0;
         for( i = 0; i < ROUNDS; i++ )
         {
-            if( ( send_ret[i] > 0 ) ||
-                    ( send_ret[i] == MBEDTLS_ERR_SSL_WANT_WRITE ) )
-            {
-                progress++;
-            }
-
-            if( ( recv_ret[i] > 0 ) ||
-                    ( recv_ret[i] == MBEDTLS_ERR_SSL_WANT_READ ) )
-            {
-                progress++;
-            }
+            progress += send_ret[i] + recv_ret[i];
         }
     }
 
@@ -1132,6 +1715,583 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE */
+void ssl_message_queue_sanity( )
+{
+    mbedtls_test_message_queue queue;
+
+    /* Trying to push/pull to an empty queue */
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( NULL, 1 )
+                 == MBEDTLS_TEST_ERROR_ARG_NULL );
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( NULL, 1 )
+                 == MBEDTLS_TEST_ERROR_ARG_NULL );
+
+    mbedtls_test_message_queue_setup( &queue, 3 );
+    TEST_ASSERT( queue.capacity == 3 );
+    TEST_ASSERT( queue.num == 0 );
+
+exit:
+    mbedtls_test_message_queue_free( &queue );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_queue_basic( )
+{
+    mbedtls_test_message_queue queue;
+
+    mbedtls_test_message_queue_setup( &queue, 3 );
+
+    /* Sanity test - 3 pushes and 3 pops with sufficient space */
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( queue.capacity == 3 );
+    TEST_ASSERT( queue.num == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( queue.capacity == 3 );
+    TEST_ASSERT( queue.num == 2 );
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 2 ) == 2 );
+    TEST_ASSERT( queue.capacity == 3 );
+    TEST_ASSERT( queue.num == 3 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 2 ) == 2 );
+
+exit:
+    mbedtls_test_message_queue_free( &queue );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_queue_overflow_underflow( )
+{
+    mbedtls_test_message_queue queue;
+
+    mbedtls_test_message_queue_setup( &queue, 3 );
+
+    /* 4 pushes (last one with an error), 4 pops (last one with an error) */
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 2 ) == 2 );
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 3 )
+                 == MBEDTLS_TEST_ERROR_QUEUE_FULL );
+
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 2 ) == 2 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 1 )
+                 == MBEDTLS_TEST_ERROR_QUEUE_EMPTY );
+
+exit:
+    mbedtls_test_message_queue_free( &queue );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_queue_interleaved( )
+{
+    mbedtls_test_message_queue queue;
+
+    mbedtls_test_message_queue_setup( &queue, 3 );
+
+    /* Interleaved test - [2 pushes, 1 pop] twice, and then two pops
+     * (to wrap around the buffer) */
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 1 ) == 1 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 1 ) == 1 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 2 ) == 2 );
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 3 ) == 3 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 1 ) == 1 );
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 2 ) == 2 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 5 ) == 5 );
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, 8 ) == 8 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 3 ) == 3 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 5 ) == 5 );
+
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, 8 ) == 8 );
+
+exit:
+    mbedtls_test_message_queue_free( &queue );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_queue_insufficient_buffer( )
+{
+    mbedtls_test_message_queue queue;
+    size_t message_len = 10;
+    size_t buffer_len = 5;
+
+    mbedtls_test_message_queue_setup( &queue, 1 );
+
+    /* Popping without a sufficient buffer */
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &queue, message_len )
+                 == (int) message_len );
+    TEST_ASSERT( mbedtls_test_message_queue_pop_info( &queue, buffer_len )
+                 == (int) buffer_len );
+exit:
+    mbedtls_test_message_queue_free( &queue );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_mock_uninitialized( )
+{
+    enum { MSGLEN = 10 };
+    unsigned char message[MSGLEN], received[MSGLEN];
+    mbedtls_mock_socket client, server;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+
+    /* Send with a NULL context */
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( NULL, message, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_CONTEXT_ERROR );
+
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( NULL, message, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_CONTEXT_ERROR );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &server_queue, &client_queue, 1,
+                                               &server,
+                                               &server_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &client_queue, &server_queue, 1,
+                                               &client,
+                                               &client_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_SEND_FAILED );
+
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_QUEUE_EMPTY );
+
+    /* Push directly to a queue to later simulate a disconnected behavior */
+    TEST_ASSERT( mbedtls_test_message_queue_push_info( &server_queue, MSGLEN )
+                 == MSGLEN );
+
+    /* Test if there's an error when trying to read from a disconnected
+     * socket */
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_RECV_FAILED );
+    exit:
+    mbedtls_message_socket_close( &server_context );
+    mbedtls_message_socket_close( &client_context );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_mock_basic( )
+{
+    enum { MSGLEN = 10 };
+    unsigned char message[MSGLEN], received[MSGLEN];
+    mbedtls_mock_socket client, server;
+    unsigned i;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &server_queue, &client_queue, 1,
+                                               &server,
+                                               &server_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &client_queue, &server_queue, 1,
+                                               &client,
+                                               &client_context ) == 0 );
+
+    /* Fill up the buffer with structured data so that unwanted changes
+     * can be detected */
+    for( i = 0; i < MSGLEN; i++ )
+    {
+        message[i] = i & 0xFF;
+    }
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
+                                                   MSGLEN ) );
+
+    /* Send the message to the server */
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN ) == MSGLEN );
+
+    /* Read from the server */
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MSGLEN );
+
+    TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+    memset( received, 0, MSGLEN );
+
+    /* Send the message to the client */
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &server_context, message,
+                                            MSGLEN ) == MSGLEN );
+
+    /* Read from the client */
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &client_context, received, MSGLEN )
+                 == MSGLEN );
+    TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+
+    exit:
+    mbedtls_message_socket_close( &server_context );
+    mbedtls_message_socket_close( &client_context );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_mock_queue_overflow_underflow( )
+{
+    enum { MSGLEN = 10 };
+    unsigned char message[MSGLEN], received[MSGLEN];
+    mbedtls_mock_socket client, server;
+    unsigned i;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &server_queue, &client_queue, 2,
+                                               &server,
+                                               &server_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &client_queue, &server_queue, 2,
+                                               &client,
+                                               &client_context ) == 0 );
+
+    /* Fill up the buffer with structured data so that unwanted changes
+     * can be detected */
+    for( i = 0; i < MSGLEN; i++ )
+    {
+        message[i] = i & 0xFF;
+    }
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
+                                                   MSGLEN*2 ) );
+
+    /* Send three message to the server, last one with an error */
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN - 1 ) == MSGLEN - 1 );
+
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN ) == MSGLEN );
+
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN )
+                 == MBEDTLS_TEST_ERROR_QUEUE_FULL );
+
+    /* Read three messages from the server, last one with an error */
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received,
+                                            MSGLEN - 1 ) == MSGLEN - 1 );
+
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MSGLEN );
+
+    TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_QUEUE_EMPTY );
+
+    exit:
+    mbedtls_message_socket_close( &server_context );
+    mbedtls_message_socket_close( &client_context );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_mock_socket_overflow( )
+{
+    enum { MSGLEN = 10 };
+    unsigned char message[MSGLEN], received[MSGLEN];
+    mbedtls_mock_socket client, server;
+    unsigned i;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &server_queue, &client_queue, 2,
+                                               &server,
+                                               &server_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &client_queue, &server_queue, 2,
+                                               &client,
+                                               &client_context ) == 0 );
+
+    /* Fill up the buffer with structured data so that unwanted changes
+     * can be detected */
+    for( i = 0; i < MSGLEN; i++ )
+    {
+        message[i] = i & 0xFF;
+    }
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
+                                                   MSGLEN ) );
+
+    /* Send two message to the server, second one with an error */
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN ) == MSGLEN );
+
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN )
+                 == MBEDTLS_TEST_ERROR_SEND_FAILED );
+
+    /* Read the only message from the server */
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MSGLEN );
+
+    TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+
+    exit:
+    mbedtls_message_socket_close( &server_context );
+    mbedtls_message_socket_close( &client_context );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_mock_truncated( )
+{
+    enum { MSGLEN = 10 };
+    unsigned char message[MSGLEN], received[MSGLEN];
+    mbedtls_mock_socket client, server;
+    unsigned i;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &server_queue, &client_queue, 2,
+                                               &server,
+                                               &server_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &client_queue, &server_queue, 2,
+                                               &client,
+                                               &client_context ) == 0 );
+
+    memset( received, 0, MSGLEN );
+    /* Fill up the buffer with structured data so that unwanted changes
+     * can be detected */
+    for( i = 0; i < MSGLEN; i++ )
+    {
+        message[i] = i & 0xFF;
+    }
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
+                                                   2 * MSGLEN ) );
+
+    /* Send two messages to the server, the second one small enough to fit in the
+     * receiver's buffer. */
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN ) == MSGLEN );
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN / 2 ) == MSGLEN / 2 );
+    /* Read a truncated message from the server */
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN/2 )
+                 == MSGLEN/2 );
+
+    /* Test that the first half of the message is valid, and second one isn't */
+    TEST_ASSERT( memcmp( message, received, MSGLEN/2 ) == 0 );
+    TEST_ASSERT( memcmp( message + MSGLEN/2, received + MSGLEN/2, MSGLEN/2 )
+                 != 0 );
+    memset( received, 0, MSGLEN );
+
+    /* Read a full message from the server */
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN/2 )
+                 == MSGLEN / 2 );
+
+    /* Test that the first half of the message is valid */
+    TEST_ASSERT( memcmp( message, received, MSGLEN/2 ) == 0 );
+
+    exit:
+    mbedtls_message_socket_close( &server_context );
+    mbedtls_message_socket_close( &client_context );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_mock_socket_read_error( )
+{
+    enum { MSGLEN = 10 };
+    unsigned char message[MSGLEN], received[MSGLEN];
+    mbedtls_mock_socket client, server;
+    unsigned i;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &server_queue, &client_queue, 1,
+                                               &server,
+                                               &server_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &client_queue, &server_queue, 1,
+                                               &client,
+                                               &client_context ) == 0 );
+
+    /* Fill up the buffer with structured data so that unwanted changes
+     * can be detected */
+    for( i = 0; i < MSGLEN; i++ )
+    {
+        message[i] = i & 0xFF;
+    }
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
+                                                   MSGLEN ) );
+
+    TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                            MSGLEN ) == MSGLEN );
+
+    /* Force a read error by disconnecting the socket by hand */
+    server.status = 0;
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_RECV_FAILED );
+    /* Return to a valid state */
+    server.status = MBEDTLS_MOCK_SOCKET_CONNECTED;
+
+    memset( received, 0, sizeof( received ) );
+
+    /* Test that even though the server tried to read once disconnected, the
+     * continuity is preserved */
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MSGLEN );
+
+    TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+
+    exit:
+    mbedtls_message_socket_close( &server_context );
+    mbedtls_message_socket_close( &client_context );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_mock_interleaved_one_way( )
+{
+    enum { MSGLEN = 10 };
+    unsigned char message[MSGLEN], received[MSGLEN];
+    mbedtls_mock_socket client, server;
+    unsigned i;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &server_queue, &client_queue, 3,
+                                               &server,
+                                               &server_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &client_queue, &server_queue, 3,
+                                               &client,
+                                               &client_context ) == 0 );
+
+    /* Fill up the buffer with structured data so that unwanted changes
+     * can be detected */
+    for( i = 0; i < MSGLEN; i++ )
+    {
+        message[i] = i & 0xFF;
+    }
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
+                                                   MSGLEN*3 ) );
+
+    /* Interleaved test - [2 sends, 1 read] twice, and then two reads
+     * (to wrap around the buffer) */
+    for( i = 0; i < 2; i++ )
+    {
+        TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                                MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                                MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received,
+                                                MSGLEN ) == MSGLEN );
+        TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+        memset( received, 0, sizeof( received ) );
+    }
+
+    for( i = 0; i < 2; i++ )
+    {
+        TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received,
+                                                MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+    }
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_QUEUE_EMPTY );
+    exit:
+    mbedtls_message_socket_close( &server_context );
+    mbedtls_message_socket_close( &client_context );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void ssl_message_mock_interleaved_two_ways( )
+{
+    enum { MSGLEN = 10 };
+    unsigned char message[MSGLEN], received[MSGLEN];
+    mbedtls_mock_socket client, server;
+    unsigned i;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &server_queue, &client_queue, 3,
+                                               &server,
+                                               &server_context ) == 0 );
+
+    TEST_ASSERT( mbedtls_message_socket_setup( &client_queue, &server_queue, 3,
+                                               &client,
+                                               &client_context ) == 0 );
+
+    /* Fill up the buffer with structured data so that unwanted changes
+     * can be detected */
+    for( i = 0; i < MSGLEN; i++ )
+    {
+        message[i] = i & 0xFF;
+    }
+    TEST_ASSERT( 0 == mbedtls_mock_socket_connect( &client, &server,
+                                                   MSGLEN*3 ) );
+
+    /* Interleaved test - [2 sends, 1 read] twice, both ways, and then two reads
+     * (to wrap around the buffer) both ways. */
+    for( i = 0; i < 2; i++ )
+    {
+        TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                                MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( mbedtls_mock_tcp_send_msg( &client_context, message,
+                                                MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( mbedtls_mock_tcp_send_msg( &server_context, message,
+                                                MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( mbedtls_mock_tcp_send_msg( &server_context, message,
+                                                MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received,
+                     MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+
+        memset( received, 0, sizeof( received ) );
+
+        TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &client_context, received,
+                     MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+
+        memset( received, 0, sizeof( received ) );
+    }
+
+    for( i = 0; i < 2; i++ )
+    {
+        TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received,
+                    MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+        memset( received, 0, sizeof( received ) );
+
+        TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &client_context, received,
+                     MSGLEN ) == MSGLEN );
+
+        TEST_ASSERT( memcmp( message, received, MSGLEN ) == 0 );
+        memset( received, 0, sizeof( received ) );
+    }
+
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &server_context, received, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_QUEUE_EMPTY );
+
+    TEST_ASSERT( mbedtls_mock_tcp_recv_msg( &client_context, received, MSGLEN )
+                 == MBEDTLS_TEST_ERROR_QUEUE_EMPTY );
+    exit:
+    mbedtls_message_socket_close( &server_context );
+    mbedtls_message_socket_close( &client_context );
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_SSL_DTLS_ANTI_REPLAY */
 void ssl_dtls_replay( data_t * prevs, data_t * new, int ret )
 {
@@ -1755,3 +2915,64 @@
 
 }
 /* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_ECDSA_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED:MBEDTLS_ECP_DP_SECP384R1_ENABLED:!MBEDTLS_USE_PSA_CRYPTO */
+void mbedtls_endpoint_sanity( int endpoint_type )
+{
+    enum { BUFFSIZE = 1024 };
+    mbedtls_endpoint ep;
+    int ret = -1;
+
+    ret = mbedtls_endpoint_init( NULL, endpoint_type );
+    TEST_ASSERT( MBEDTLS_ERR_SSL_BAD_INPUT_DATA == ret );
+
+    ret = mbedtls_endpoint_certificate_init( NULL );
+    TEST_ASSERT( MBEDTLS_ERR_SSL_BAD_INPUT_DATA == ret );
+
+    ret = mbedtls_endpoint_init( &ep, endpoint_type );
+    TEST_ASSERT( ret == 0 );
+
+exit:
+    mbedtls_endpoint_free( &ep );
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_ECDSA_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED:MBEDTLS_ECP_DP_SECP384R1_ENABLED:!MBEDTLS_USE_PSA_CRYPTO */
+void move_handshake_to_state(int endpoint_type, int state, int need_pass)
+{
+    enum { BUFFSIZE = 1024 };
+    mbedtls_endpoint base_ep, second_ep;
+    int ret = -1;
+
+    ret = mbedtls_endpoint_init( &base_ep, endpoint_type );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_endpoint_init( &second_ep,
+                            ( endpoint_type == MBEDTLS_SSL_IS_SERVER ) ?
+                            MBEDTLS_SSL_IS_CLIENT : MBEDTLS_SSL_IS_SERVER );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_mock_socket_connect( &(base_ep.socket),
+                                       &(second_ep.socket),
+                                       BUFFSIZE );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_move_handshake_to_state( &(base_ep.ssl),
+                                           &(second_ep.ssl),
+                                           state );
+    if( need_pass )
+    {
+        TEST_ASSERT( ret == 0 );
+        TEST_ASSERT( base_ep.ssl.state == state );
+    }
+    else
+    {
+        TEST_ASSERT( ret != 0 );
+        TEST_ASSERT( base_ep.ssl.state != state );
+    }
+
+exit:
+    mbedtls_endpoint_free( &base_ep );
+    mbedtls_endpoint_free( &second_ep );
+}
+/* END_CASE */
diff --git a/tests/suites/test_suite_version.data b/tests/suites/test_suite_version.data
index b6dca23..ff0612b 100644
--- a/tests/suites/test_suite_version.data
+++ b/tests/suites/test_suite_version.data
@@ -1,8 +1,8 @@
 Check compiletime library version
-check_compiletime_version:"2.19.1"
+check_compiletime_version:"2.20.0"
 
 Check runtime library version
-check_runtime_version:"2.19.1"
+check_runtime_version:"2.20.0"
 
 Check for MBEDTLS_VERSION_C
 check_feature:"MBEDTLS_VERSION_C":0