diff --git a/.github/issue_template.md b/.github/issue_template.md
index 33f68fb..5e9d83d 100644
--- a/.github/issue_template.md
+++ b/.github/issue_template.md
@@ -8,7 +8,7 @@
 ## Bug
 
 **OS**  
-mbed-OS|linux|windows|
+Mbed OS|linux|windows|
 
 **mbed TLS build:**  
 Version: x.x.x or git commit id  
@@ -38,4 +38,4 @@
 
 ## Question
 
-**Please first check for answers in the [mbed TLS knowledge Base](https://tls.mbed.org/kb), and preferebly file an issue in the [mbed TLS support forum](https://tls.mbed.org/discussions)**  
+**Please first check for answers in the [Mbed TLS knowledge Base](https://tls.mbed.org/kb), and preferably file an issue in the [Mbed TLS support forum](https://tls.mbed.org/discussions)**  
diff --git a/ChangeLog b/ChangeLog
index 1154075..0d323b1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,22 @@
      was independently reported by Tim Nordell via e-mail and by Florin Petriuc
      and sjorsdewit on GitHub. Fix proposed by Florin Petriuc in #1022. Fixes #707.
 
+Features
+   * Allow comments in test data files.
+
+Bugfix
+   * Fix ssl_parse_record_header() to silently discard invalid DTLS records
+     as recommended in RFC 6347 Section 4.1.2.7.
+   * Fix memory leak in mbedtls_ssl_set_hostname() when called multiple times.
+     Found by projectgus and jethrogb, #836.
+   * Fix usage help in ssl_server2 example. Found and fixed by Bei Lin.
+   * Parse signature algorithm extension when renegotiating. Previously,
+     renegotiated handshakes would only accept signatures using SHA-1
+     regardless of the peer's preferences, or fail if SHA-1 was disabled.
+   * Fix leap year calculation in x509_date_is_valid() to ensure that invalid
+     dates on leap years with 100 and 400 intervals are handled correctly. Found
+     by Nicholas Wilson. #694
+
 = mbed TLS 2.6.0 branch released 2017-08-10
 
 Security
diff --git a/README.md b/README.md
index 11b4ebf..4270e80 100644
--- a/README.md
+++ b/README.md
@@ -1,37 +1,37 @@
-README for mbed TLS
+README for Mbed TLS
 ===================
 
 Configuration
 -------------
 
-mbed TLS should build out of the box on most systems. Some platform specific options are available in the fully documented configuration file `include/mbedtls/config.h`, which is also the place where features can be selected. This file can be edited manually, or in a more programmatic way using the Perl script `scripts/config.pl` (use `--help` for usage instructions).
+Mbed TLS should build out of the box on most systems. Some platform specific options are available in the fully documented configuration file `include/mbedtls/config.h`, which is also the place where features can be selected. This file can be edited manually, or in a more programmatic way using the Perl script `scripts/config.pl` (use `--help` for usage instructions).
 
 Compiler options can be set using conventional environment variables such as `CC` and `CFLAGS` when using the Make and CMake build system (see below).
 
 Compiling
 ---------
 
-There are currently four active build systems used within mbed TLS releases:
+There are currently four active build systems used within Mbed TLS releases:
 
 -   yotta
--   Make
+-   GNU Make
 -   CMake
--   Microsoft Visual Studio (Visual Studio 6 and Visual Studio 2010)
+-   Microsoft Visual Studio (Microsoft Visual Studio 2010 or later)
 
-The main systems used for development are CMake and Make. Those systems are always complete and up-to-date. The others should reflect all changes present in the CMake and Make build system, although features may not be ported there automatically.
+The main systems used for development are CMake and GNU Make. Those systems are always complete and up-to-date. The others should reflect all changes present in the CMake and Make build system, although features may not be ported there automatically.
 
 Yotta, as a build system, is slightly different from the other build systems:
 
 -   it provides a minimalistic configuration file by default
--   depending on the yotta target, features of mbed OS may be used in examples and tests
+-   depending on the yotta target, features of Mbed OS may be used in examples and tests
 
 The Make and CMake build systems create three libraries: libmbedcrypto, libmbedx509, and libmbedtls. Note that libmbedtls depends on libmbedx509 and libmbedcrypto, and libmbedx509 depends on libmbedcrypto. As a result, some linkers will expect flags to be in a specific order, for example the GNU linker wants `-lmbedtls -lmbedx509 -lmbedcrypto`. Also, when loading shared libraries using dlopen(), you'll need to load libmbedcrypto first, then libmbedx509, before you can load libmbedtls.
 
 ### Yotta
 
-[yotta](http://yottabuild.org) is a package manager and build system developed by mbed, and is the build system of mbed OS 16.03. To install it on your platform, please follow the yotta [installation instructions](http://docs.yottabuild.org/#installing).
+[yotta](http://yottabuild.org) is a package manager and build system developed by Mbed, and is the build system of Mbed OS 16.03. To install it on your platform, please follow the yotta [installation instructions](http://docs.yottabuild.org/#installing).
 
-Once yotta is installed, you can use it to download the latest version of mbed TLS from the yotta registry with:
+Once yotta is installed, you can use it to download the latest version of Mbed TLS from the yotta registry with:
 
     yotta install mbedtls
 
@@ -39,24 +39,26 @@
 
     yotta build
 
-If, on the other hand, you already have a copy of mbed TLS from a source other than the yotta registry, for example from cloning our GitHub repository, or from downloading a tarball of the standalone edition, then you'll first need to generate the yotta module by running:
+If, on the other hand, you already have a copy of Mbed TLS from a source other than the yotta registry, for example from cloning our GitHub repository, or from downloading a tarball of the standalone edition, then you'll first need to generate the yotta module by running:
 
     yotta/create-module.sh
 
-This should be executed from the root mbed TLS project directory. This will create the yotta module in the `yotta/module` directory within it. You can then change to that directory and build as usual:
+This should be executed from the root Mbed TLS project directory. This will create the yotta module in the `yotta/module` directory within it. You can then change to that directory and build as usual:
 
     cd yotta/module
     yotta build
 
 In any case, you'll probably want to set the yotta target before building unless it has already been set globally. For more information on using yotta, please consult the [yotta documentation](http://docs.yottabuild.org/).
 
-For more details on the yotta/mbed OS edition of mbed TLS, including example programs, please consult the [Readme at the root of the yotta module](https://github.com/ARMmbed/mbedtls/blob/development/yotta/data/README.md).
+For more details on the yotta/Mbed OS edition of Mbed TLS, including example programs, please consult the [Readme at the root of the yotta module](https://github.com/ARMmbed/mbedtls/blob/development/yotta/data/README.md).
 
 ### Make
 
-We intentionally only use the minimum of `Make` functionality, as a lot of `Make` features are not supported on all different implementations of Make or on different platforms. As such, the Makefiles sometimes require some manual changes or export statements in order to work for your platform.
+We require GNU Make. To build the library and the sample programs, GNU Make and a C compiler are sufficient. Some of the more advanced build targets require some Unix/Linux tools.
 
-In order to build from the source code using Make, just enter at the command line:
+We intentionally only use a minimum of functionality in the makefiles in order to keep them as simple and independent of different toolchains as possible, to allow users to more easily move between different platforms. Users who need more features are recommended to use CMake.
+
+In order to build from the source code using GNU Make, just enter at the command line:
 
     make
 
@@ -76,9 +78,9 @@
 
 Setting the variable `SHARED` in your environment will build shared libraries in addition to the static libraries. Setting `DEBUG` gives you a debug build. You can override `CFLAGS` and `LDFLAGS` by setting them in your environment or on the make command line; if you do so, essential parts such as `-I` will still be preserved. Warning options may be overridden separately using `WARNING_CFLAGS`.
 
-Depending on your platform, you might run into some issues. Please check the Makefiles in `library/`, `programs/` and `tests/` for options to manually add or remove for specific platforms. You can also check [the mbed TLS Knowledge Base](https://tls.mbed.org/kb) for articles on your platform or issue.
+Depending on your platform, you might run into some issues. Please check the Makefiles in `library/`, `programs/` and `tests/` for options to manually add or remove for specific platforms. You can also check [the Mbed TLS Knowledge Base](https://tls.mbed.org/kb) for articles on your platform or issue.
 
-In case you find that you need to do something else as well, please let us know what, so we can add it to the [mbed TLS knowledge base](https://tls.mbed.org/kb).
+In case you find that you need to do something else as well, please let us know what, so we can add it to the [Mbed TLS knowledge base](https://tls.mbed.org/kb).
 
 ### CMake
 
@@ -141,7 +143,7 @@
 Tests
 -----
 
-mbed TLS includes an elaborate test suite in `tests/` that initially requires Perl to generate the tests files (e.g. `test\_suite\_mpi.c`). These files are generated from a `function file` (e.g. `suites/test\_suite\_mpi.function`) and a `data file` (e.g. `suites/test\_suite\_mpi.data`). The `function file` contains the test functions. The `data file` contains the test cases, specified as parameters that will be passed to the test function.
+Mbed TLS includes an elaborate test suite in `tests/` that initially requires Perl to generate the tests files (e.g. `test\_suite\_mpi.c`). These files are generated from a `function file` (e.g. `suites/test\_suite\_mpi.function`) and a `data file` (e.g. `suites/test\_suite\_mpi.data`). The `function file` contains the test functions. The `data file` contains the test cases, specified as parameters that will be passed to the test function.
 
 For machines with a Unix shell and OpenSSL (and optionally GnuTLS) installed, additional test scripts are available:
 
@@ -156,14 +158,14 @@
 
 We provide some non-standard configurations focused on specific use cases in the `configs/` directory. You can read more about those in `configs/README.txt`
 
-Porting mbed TLS
+Porting Mbed TLS
 ----------------
 
-mbed TLS can be ported to many different architectures, OS's and platforms. Before starting a port, you may find the following knowledge base articles useful:
+Mbed TLS can be ported to many different architectures, OS's and platforms. Before starting a port, you may find the following knowledge base articles useful:
 
--   [Porting mbed TLS to a new environment or OS](https://tls.mbed.org/kb/how-to/how-do-i-port-mbed-tls-to-a-new-environment-OS)
--   [What external dependencies does mbed TLS rely on?](https://tls.mbed.org/kb/development/what-external-dependencies-does-mbedtls-rely-on)
--   [How do I configure mbed TLS](https://tls.mbed.org/kb/compiling-and-building/how-do-i-configure-mbedtls)
+-   [Porting Mbed TLS to a new environment or OS](https://tls.mbed.org/kb/how-to/how-do-i-port-mbed-tls-to-a-new-environment-OS)
+-   [What external dependencies does Mbed TLS rely on?](https://tls.mbed.org/kb/development/what-external-dependencies-does-mbedtls-rely-on)
+-   [How do I configure Mbed TLS](https://tls.mbed.org/kb/compiling-and-building/how-do-i-configure-mbedtls)
 
 Contributing
 ------------
@@ -174,12 +176,12 @@
 -   We would ask that contributions conform to [our coding standards](https://tls.mbed.org/kb/development/mbedtls-coding-standards), and that contributions should be fully tested before submission.
 -   As with any open source project, contributions will be reviewed by the project team and community and may need some modifications to be accepted.
 
-To accept the Contributor’s Licence Agreement (CLA), individual contributors can do this by creating an mbed account and [accepting the online agreement here with a click through](https://developer.mbed.org/contributor_agreement/). Alternatively, for contributions from corporations, or those that do not wish to create an mbed account, a slightly different agreement can be found [here](https://www.mbed.com/en/about-mbed/contributor-license-agreements/). This agreement should be signed and returned to ARM as described in the instructions given.
+To accept the Contributor’s Licence Agreement (CLA), individual contributors can do this by creating an Mbed account and [accepting the online agreement here with a click through](https://os.mbed.com/contributor_agreement/). Alternatively, for contributions from corporations, or those that do not wish to create an Mbed account, a slightly different agreement can be found [here](https://www.mbed.com/en/about-mbed/contributor-license-agreements/). This agreement should be signed and returned to Arm as described in the instructions given.
 
 ### Making a Contribution
 
 1.  [Check for open issues](https://github.com/ARMmbed/mbedtls/issues) or [start a discussion](https://tls.mbed.org/discussions) around a feature idea or a bug.
-2.  Fork the [mbed TLS repository on GitHub](https://github.com/ARMmbed/mbedtls) to start making your changes. As a general rule, you should use the "development" branch as a basis.
+2.  Fork the [Mbed TLS repository on GitHub](https://github.com/ARMmbed/mbedtls) to start making your changes. As a general rule, you should use the "development" branch as a basis.
 3.  Write a test which shows that the bug was fixed or that the feature works as expected.
 4.  Send a pull request and bug us until it gets merged and published. Contributions may need some modifications, so work with us to get your change accepted. We will include your name in the ChangeLog :)
 
diff --git a/configs/README.txt b/configs/README.txt
index e9867bc..933fa7f 100644
--- a/configs/README.txt
+++ b/configs/README.txt
@@ -8,7 +8,7 @@
 them, you can pick one of the following methods:
 
 1. Replace the default file include/mbedtls/config.h with the chosen one.
-   (Depending on your compiler, you may need to ajust the line with
+   (Depending on your compiler, you may need to adjust the line with
    #include "mbedtls/check_config.h" then.)
 
 2. Define MBEDTLS_CONFIG_FILE and adjust the include path accordingly.
diff --git a/include/mbedtls/asn1.h b/include/mbedtls/asn1.h
index 082832c..e159e57 100644
--- a/include/mbedtls/asn1.h
+++ b/include/mbedtls/asn1.h
@@ -59,7 +59,7 @@
 
 /**
  * \name DER constants
- * These constants comply with DER encoded the ANS1 type tags.
+ * These constants comply with the DER encoded ASN.1 type tags.
  * DER encoding uses hexadecimal representation.
  * An example DER sequence is:\n
  * - 0x02 -- tag indicating INTEGER
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index cc00070..e98101e 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1794,15 +1794,22 @@
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
 /**
- * \brief          Set the hostname to check against the received server
- *                 certificate. It sets the ServerName TLS extension too,
- *                 if the extension is enabled.
- *                 (client-side only)
+ * \brief          Set or reset the hostname to check against the received 
+ *                 server certificate. It sets the ServerName TLS extension, 
+ *                 too, if that extension is enabled. (client-side only)
  *
  * \param ssl      SSL context
- * \param hostname the server hostname
+ * \param hostname the server hostname, may be NULL to clear hostname
+ 
+ * \note           Maximum hostname length MBEDTLS_SSL_MAX_HOST_NAME_LEN.
  *
- * \return         0 if successful or MBEDTLS_ERR_SSL_ALLOC_FAILED
+ * \return         0 if successful, MBEDTLS_ERR_SSL_ALLOC_FAILED on 
+ *                 allocation failure, MBEDTLS_ERR_SSL_BAD_INPUT_DATA on 
+ *                 too long input hostname.
+ *
+ *                 Hostname set to the one provided on success (cleared
+ *                 when NULL). On allocation failure hostname is cleared. 
+ *                 On too long input failure, old hostname is unchanged.
  */
 int mbedtls_ssl_set_hostname( mbedtls_ssl_context *ssl, const char *hostname );
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
diff --git a/library/net_sockets.c b/library/net_sockets.c
index 80be6ec..31c42db 100644
--- a/library/net_sockets.c
+++ b/library/net_sockets.c
@@ -63,8 +63,8 @@
 #endif
 #endif /* _MSC_VER */
 
-#define read(fd,buf,len)        recv(fd,(char*)buf,(int) len,0)
-#define write(fd,buf,len)       send(fd,(char*)buf,(int) len,0)
+#define read(fd,buf,len)        recv( fd, (char*)( buf ), (int)( len ), 0 )
+#define write(fd,buf,len)       send( fd, (char*)( buf ), (int)( len ), 0 )
 #define close(fd)               closesocket(fd)
 
 static int wsa_init_done = 0;
@@ -85,7 +85,7 @@
 #endif /* ( _WIN32 || _WIN32_WCE ) && !EFIX64 && !EFI32 */
 
 /* Some MS functions want int and MSVC warns if we pass size_t,
- * but the standard fucntions use socklen_t, so cast only for MSVC */
+ * but the standard functions use socklen_t, so cast only for MSVC */
 #if defined(_MSC_VER)
 #define MSVC_INT_CAST   (int)
 #else
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index a2b9f8c..544c8cf 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -80,6 +80,13 @@
     }
 
     /*
+     * Sect. 3, RFC 6066 (TLS Extensions Definitions)
+     *
+     * In order to provide any of the server names, clients MAY include an
+     * extension of type "server_name" in the (extended) client hello. The
+     * "extension_data" field of this extension SHALL contain
+     * "ServerNameList" where:
+     *
      * struct {
      *     NameType name_type;
      *     select (name_type) {
@@ -96,6 +103,7 @@
      * struct {
      *     ServerName server_name_list<1..2^16-1>
      * } ServerNameList;
+     *
      */
     *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME >> 8 ) & 0xFF );
     *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME      ) & 0xFF );
@@ -1440,9 +1448,6 @@
 #endif
     int handshake_failure = 0;
     const mbedtls_ssl_ciphersuite_t *suite_info;
-#if defined(MBEDTLS_DEBUG_C)
-    uint32_t t;
-#endif
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse server hello" ) );
 
@@ -1545,13 +1550,11 @@
         return( MBEDTLS_ERR_SSL_BAD_HS_PROTOCOL_VERSION );
     }
 
-#if defined(MBEDTLS_DEBUG_C)
-    t = ( (uint32_t) buf[2] << 24 )
-      | ( (uint32_t) buf[3] << 16 )
-      | ( (uint32_t) buf[4] <<  8 )
-      | ( (uint32_t) buf[5]       );
-    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, current time: %lu", t ) );
-#endif
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, current time: %lu",
+                           ( (uint32_t) buf[2] << 24 ) |
+                           ( (uint32_t) buf[3] << 16 ) |
+                           ( (uint32_t) buf[4] <<  8 ) |
+                           ( (uint32_t) buf[5]       ) ) );
 
     memcpy( ssl->handshake->randbytes + 32, buf + 2, 32 );
 
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index f137c3d..37f415d 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -1694,11 +1694,8 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
     defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
             case MBEDTLS_TLS_EXT_SIG_ALG:
-                    MBEDTLS_SSL_DEBUG_MSG( 3, ( "found signature_algorithms extension" ) );
-#if defined(MBEDTLS_SSL_RENEGOTIATION)
-                if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
-                    break;
-#endif
+                MBEDTLS_SSL_DEBUG_MSG( 3, ( "found signature_algorithms extension" ) );
+
                 ret = ssl_parse_signature_algorithms_ext( ssl, ext + 4, ext_size );
                 if( ret != 0 )
                     return( ret );
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index b6e0eaa..e19dfc9 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -3493,8 +3493,15 @@
         ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type" ) );
-        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
-                                        MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+        /* Silently ignore invalid DTLS records as recommended by RFC 6347
+         * Section 4.1.2.7 */
+        if( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+            mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                    MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
+
         return( MBEDTLS_ERR_SSL_INVALID_RECORD );
     }
 
@@ -6159,7 +6166,7 @@
 {
     conf->sig_hashes = hashes;
 }
-#endif
+#endif /* MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
 
 #if defined(MBEDTLS_ECP_C)
 /*
@@ -6170,36 +6177,53 @@
 {
     conf->curve_list = curve_list;
 }
-#endif
+#endif /* MBEDTLS_ECP_C */
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
 int mbedtls_ssl_set_hostname( mbedtls_ssl_context *ssl, const char *hostname )
 {
-    size_t hostname_len;
+    /* Initialize to suppress unnecessary compiler warning */
+    size_t hostname_len = 0;
+
+    /* Check if new hostname is valid before
+     * making any change to current one */
+    if( hostname != NULL )
+    {
+        hostname_len = strlen( hostname );
+
+        if( hostname_len > MBEDTLS_SSL_MAX_HOST_NAME_LEN )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    /* Now it's clear that we will overwrite the old hostname,
+     * so we can free it safely */
+
+    if( ssl->hostname != NULL )
+    {
+        mbedtls_zeroize( ssl->hostname, strlen( ssl->hostname ) );
+        mbedtls_free( ssl->hostname );
+    }
+
+    /* Passing NULL as hostname shall clear the old one */
 
     if( hostname == NULL )
-        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    {
+        ssl->hostname = NULL;
+    }
+    else
+    {
+        ssl->hostname = mbedtls_calloc( 1, hostname_len + 1 );
+        if( ssl->hostname == NULL )
+            return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
 
-    hostname_len = strlen( hostname );
+        memcpy( ssl->hostname, hostname, hostname_len );
 
-    if( hostname_len + 1 == 0 )
-        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
-
-    if( hostname_len > MBEDTLS_SSL_MAX_HOST_NAME_LEN )
-        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
-
-    ssl->hostname = mbedtls_calloc( 1, hostname_len + 1 );
-
-    if( ssl->hostname == NULL )
-        return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
-
-    memcpy( ssl->hostname, hostname, hostname_len );
-
-    ssl->hostname[hostname_len] = '\0';
+        ssl->hostname[hostname_len] = '\0';
+    }
 
     return( 0 );
 }
-#endif
+#endif /* MBEDTLS_X509_CRT_PARSE_C */
 
 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
 void mbedtls_ssl_conf_sni( mbedtls_ssl_config *conf,
diff --git a/library/x509.c b/library/x509.c
index e94a8a3..371d6da 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -496,9 +496,10 @@
     return( 0 );
 }
 
-static int x509_date_is_valid(const mbedtls_x509_time *t)
+static int x509_date_is_valid(const mbedtls_x509_time *t )
 {
     int ret = MBEDTLS_ERR_X509_INVALID_DATE;
+    int month_len;
 
     CHECK_RANGE( 0, 9999, t->year );
     CHECK_RANGE( 0, 23,   t->hour );
@@ -508,17 +509,22 @@
     switch( t->mon )
     {
         case 1: case 3: case 5: case 7: case 8: case 10: case 12:
-            CHECK_RANGE( 1, 31, t->day );
+            month_len = 31;
             break;
         case 4: case 6: case 9: case 11:
-            CHECK_RANGE( 1, 30, t->day );
+            month_len = 30;
             break;
         case 2:
-            CHECK_RANGE( 1, 28 + (t->year % 4 == 0), t->day );
+            if( ( !( t->year % 4 ) && t->year % 100 ) ||
+                !( t->year % 400 ) )
+                month_len = 29;
+            else
+                month_len = 28;
             break;
         default:
             return( ret );
     }
+    CHECK_RANGE( 1, month_len, t->day );
 
     return( 0 );
 }
diff --git a/programs/ssl/dtls_client.c b/programs/ssl/dtls_client.c
index e18ee42..f271bad 100644
--- a/programs/ssl/dtls_client.c
+++ b/programs/ssl/dtls_client.c
@@ -203,7 +203,7 @@
     /*
      * 4. Handshake
      */
-    mbedtls_printf( "  . Performing the SSL/TLS handshake..." );
+    mbedtls_printf( "  . Performing the DTLS handshake..." );
     fflush( stdout );
 
     do ret = mbedtls_ssl_handshake( &ssl );
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index a258868..1285abc 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -326,7 +326,7 @@
 #define USAGE \
     "\n usage: ssl_server2 param=<>...\n"                   \
     "\n acceptable parameters:\n"                           \
-    "    server_addr=%%d      default: (all interfaces)\n"  \
+    "    server_addr=%%s      default: (all interfaces)\n"  \
     "    server_port=%%d      default: 4433\n"              \
     "    debug_level=%%d      default: 0 (disabled)\n"      \
     "    nbio=%%d             default: 0 (blocking I/O)\n"  \
diff --git a/scripts/config.pl b/scripts/config.pl
index 406413b..5a06a33 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -56,7 +56,7 @@
     unset <symbol>          - Comments out the #define for the given symbol if
                               present in the configuration file.
     get <symbol>            - Finds the #define for the given symbol, returning
-                              an exitcode of 0 if the symbol is found, and -1 if
+                              an exitcode of 0 if the symbol is found, and 1 if
                               not. The value of the symbol is output if one is
                               specified in the configuration file.
     full                    - Uncomments all #define's in the configuration file
@@ -175,7 +175,10 @@
     $no_exclude_re = join '|', @non_excluded;
 }
 
-open my $config_write, '>', $config_file or die "write $config_file: $!\n";
+my $config_write = undef;
+if ($action ne "get") {
+    open $config_write, '>', $config_file or die "write $config_file: $!\n";
+}
 
 my $done;
 for my $line (@config_lines) {
@@ -205,17 +208,19 @@
             $done = 1;
         }
     } elsif (!$done && $action eq "get") {
-        if ($line =~ /^\s*#define\s*$name\s*([^\s]+)\s*\b/) {
+        if ($line =~ /^\s*#define\s*$name(?:\s+(.*?))\s*(?:$|\/\*|\/\/)/) {
             $value = $1;
             $done = 1;
         }
     }
 
-    print $config_write $line;
+    if (defined $config_write) {
+        print $config_write $line or die "write $config_file: $!\n";
+    }
 }
 
 # Did the set command work?
-if ($action eq "set"&& $force_option && !$done) {
+if ($action eq "set" && $force_option && !$done) {
 
     # If the force option was set, append the symbol to the end of the file
     my $line = "#define $name";
@@ -223,20 +228,22 @@
     $line .= "\n";
     $done = 1;
 
-    print $config_write $line;
+    print $config_write $line or die "write $config_file: $!\n";
 }
 
-close $config_write;
+if (defined $config_write) {
+    close $config_write or die "close $config_file: $!\n";
+}
 
 if ($action eq "get") {
-    if($done) {
+    if ($done) {
         if ($value ne '') {
-            print $value;
+            print "$value\n";
         }
         exit 0;
     } else {
         # If the symbol was not found, return an error
-        exit -1;
+        exit 1;
     }
 }
 
diff --git a/tests/scripts/generate_code.pl b/tests/scripts/generate_code.pl
index 84e949d..a486319 100755
--- a/tests/scripts/generate_code.pl
+++ b/tests/scripts/generate_code.pl
@@ -49,6 +49,27 @@
 #       file name is used to replace the symbol 'TESTCASE_FILENAME' in the main
 #       code file above.
 #
+#       A test data file consists of a sequence of paragraphs separated by
+#       a single empty line. Line breaks may be in Unix (LF) or Windows (CRLF)
+#       format. Lines starting with the character '#' are ignored
+#       (the parser behaves as if they were not present).
+#
+#       Each paragraph describes one test case and must consist of: (1) one
+#       line which is the test case name; (2) an optional line starting with
+#       the 11-character prefix "depends_on:"; (3) a line containing the test
+#       function to execute and its parameters.
+#
+#       A depends_on: line consists of a list of compile-time options
+#       separated by the character ':', with no whitespace. The test case
+#       is executed only if this compilation option is enabled in config.h.
+#
+#       The last line of each paragraph contains a test function name and
+#       a list of parameters separated by the character ':'. Running the
+#       test case calls this function with the specified parameters. Each
+#       parameter may either be an integer written in decimal or hexadecimal,
+#       or a string surrounded by double quotes which may not contain the
+#       ':' character.
+#
 
 use strict;
 
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index d4096e7..5dc47a3 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -321,6 +321,33 @@
     fi
 }
 
+# Given the client or server debug output, parse the unix timestamp that is
+# included in the first 4 bytes of the random bytes and check that it's within
+# acceptable bounds
+check_server_hello_time() {
+    # Extract the time from the debug (lvl 3) output of the client
+    SERVER_HELLO_TIME="$(sed -n 's/.*server hello, current time: //p' < "$1")"
+    # Get the Unix timestamp for now
+    CUR_TIME=$(date +'%s')
+    THRESHOLD_IN_SECS=300
+
+    # Check if the ServerHello time was printed
+    if [ -z "$SERVER_HELLO_TIME" ]; then
+        return 1
+    fi
+
+    # Check the time in ServerHello is within acceptable bounds
+    if [ $SERVER_HELLO_TIME -lt $(( $CUR_TIME - $THRESHOLD_IN_SECS )) ]; then
+        # The time in ServerHello is at least 5 minutes before now
+        return 1
+    elif [ $SERVER_HELLO_TIME -gt $(( $CUR_TIME + $THRESHOLD_IN_SECS )) ]; then
+        # The time in ServerHello is at least 5 minutes later than now
+        return 1
+    else
+        return 0
+    fi
+}
+
 # wait for client to terminate and set CLI_EXIT
 # must be called right after starting the client
 wait_client_done() {
@@ -357,9 +384,11 @@
 # Options:  -s pattern  pattern that must be present in server output
 #           -c pattern  pattern that must be present in client output
 #           -u pattern  lines after pattern must be unique in client output
+#           -f call shell function on client output
 #           -S pattern  pattern that must be absent in server output
 #           -C pattern  pattern that must be absent in client output
 #           -U pattern  lines after pattern must be unique in server output
+#           -F call shell function on server output
 run_test() {
     NAME="$1"
     shift 1
@@ -546,6 +575,18 @@
                     return
                 fi
                 ;;
+            "-F")
+                if ! $2 "$SRV_OUT"; then
+                    fail "function call to '$2' failed on Server output"
+                    return
+                fi
+                ;;
+            "-f")
+                if ! $2 "$CLI_OUT"; then
+                    fail "function call to '$2' failed on Client output"
+                    return
+                fi
+                ;;
 
             *)
                 echo "Unknown test: $1" >&2
@@ -682,6 +723,21 @@
             -s "Protocol is DTLSv1.2" \
             -s "Ciphersuite is TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384"
 
+# Test current time in ServerHello
+requires_config_enabled MBEDTLS_HAVE_TIME
+run_test    "Default, ServerHello contains gmt_unix_time" \
+            "$P_SRV debug_level=3" \
+            "$P_CLI debug_level=3" \
+            0 \
+            -s "Protocol is TLSv1.2" \
+            -s "Ciphersuite is TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384" \
+            -s "client hello v3, signature_algorithm ext: 6" \
+            -s "ECDHE curve: secp521r1" \
+            -S "error" \
+            -C "error" \
+            -f "check_server_hello_time" \
+            -F "check_server_hello_time"
+
 # Test for uniqueness of IVs in AEAD ciphersuites
 run_test    "Unique IV in GCM" \
             "$P_SRV exchanges=20 debug_level=4" \
@@ -1484,6 +1540,40 @@
             -s "=> renegotiate" \
             -s "write hello request"
 
+# Checks that no Signature Algorithm with SHA-1 gets negotiated. Negotiating SHA-1 would mean that
+# the server did not parse the Signature Algorithm extension. This test is valid only if an MD
+# algorithm stronger than SHA-1 is enabled in config.h
+run_test    "Renegotiation: Signature Algorithms parsing, client-initiated" \
+            "$P_SRV debug_level=3 exchanges=2 renegotiation=1 auth_mode=optional" \
+            "$P_CLI debug_level=3 exchanges=2 renegotiation=1 renegotiate=1" \
+            0 \
+            -c "client hello, adding renegotiation extension" \
+            -s "received TLS_EMPTY_RENEGOTIATION_INFO" \
+            -s "found renegotiation extension" \
+            -s "server hello, secure renegotiation extension" \
+            -c "found renegotiation extension" \
+            -c "=> renegotiate" \
+            -s "=> renegotiate" \
+            -S "write hello request" \
+            -S "client hello v3, signature_algorithm ext: 2" # Is SHA-1 negotiated?
+
+# Checks that no Signature Algorithm with SHA-1 gets negotiated. Negotiating SHA-1 would mean that
+# the server did not parse the Signature Algorithm extension. This test is valid only if an MD
+# algorithm stronger than SHA-1 is enabled in config.h
+run_test    "Renegotiation: Signature Algorithms parsing, server-initiated" \
+            "$P_SRV debug_level=3 exchanges=2 renegotiation=1 auth_mode=optional renegotiate=1" \
+            "$P_CLI debug_level=3 exchanges=2 renegotiation=1" \
+            0 \
+            -c "client hello, adding renegotiation extension" \
+            -s "received TLS_EMPTY_RENEGOTIATION_INFO" \
+            -s "found renegotiation extension" \
+            -s "server hello, secure renegotiation extension" \
+            -c "found renegotiation extension" \
+            -c "=> renegotiate" \
+            -s "=> renegotiate" \
+            -s "write hello request" \
+            -S "client hello v3, signature_algorithm ext: 2" # Is SHA-1 negotiated?
+
 run_test    "Renegotiation: double" \
             "$P_SRV debug_level=3 exchanges=2 renegotiation=1 auth_mode=optional renegotiate=1" \
             "$P_CLI debug_level=3 exchanges=2 renegotiation=1 renegotiate=1" \
diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 63815df..cac104a 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -99,7 +99,15 @@
 /*----------------------------------------------------------------------------*/
 /* Global variables */
 
-static int test_errors = 0;
+
+static struct
+{
+    int failed;
+    const char *test;
+    const char *filename;
+    int line_no;
+}
+test_info;
 
 
 /*----------------------------------------------------------------------------*/
@@ -395,10 +403,9 @@
 
 static void test_fail( const char *test, int line_no, const char* filename )
 {
-    test_errors++;
-    if( test_errors == 1 )
-        mbedtls_fprintf( stdout, "FAILED\n" );
-    mbedtls_fprintf( stdout, "  %s\n  at line %d, %s\n", test, line_no,
-                        filename );
+    test_info.failed = 1;
+    test_info.test = test;
+    test_info.line_no = line_no;
+    test_info.filename = filename;
 }
 
diff --git a/tests/suites/main_test.function b/tests/suites/main_test.function
index a7bb41d..120247e 100644
--- a/tests/suites/main_test.function
+++ b/tests/suites/main_test.function
@@ -136,18 +136,31 @@
     "TESTCASE_FILENAME"
 
 
+/** Retrieve one input line into buf, which must have room for len
+ * bytes. The trailing line break (if any) is stripped from the result.
+ * Lines beginning with the character '#' are skipped. Lines that are
+ * more than len-1 bytes long including the trailing line break are
+ * truncated; note that the following bytes remain in the input stream.
+ *
+ * \return 0 on success, -1 on error or end of file
+ */
 int get_line( FILE *f, char *buf, size_t len )
 {
     char *ret;
 
-    ret = fgets( buf, len, f );
-    if( ret == NULL )
-        return( -1 );
+    do
+    {
+        ret = fgets( buf, len, f );
+        if( ret == NULL )
+            return( -1 );
+    }
+    while( buf[0] == '#' );
 
-    if( strlen( buf ) && buf[strlen(buf) - 1] == '\n' )
-        buf[strlen(buf) - 1] = '\0';
-    if( strlen( buf ) && buf[strlen(buf) - 1] == '\r' )
-        buf[strlen(buf) - 1] = '\0';
+    ret = buf + strlen( buf );
+    if( ret-- > buf && *ret == '\n' )
+        *ret = '\0';
+    if( ret-- > buf && *ret == '\r' )
+        *ret = '\0';
 
     return( 0 );
 }
@@ -326,6 +339,9 @@
         testfile_count = 1;
     }
 
+    /* Initialize the struct that holds information about the last test */
+    memset( &test_info, 0, sizeof( test_info ) );
+
     /* Now begin to execute the tests in the testfiles */
     for ( testfile_index = 0;
           testfile_index < testfile_count;
@@ -356,7 +372,7 @@
 
             if( ( ret = get_line( file, buf, sizeof(buf) ) ) != 0 )
                 break;
-            mbedtls_fprintf( stdout, "%s%.66s", test_errors ? "\n" : "", buf );
+            mbedtls_fprintf( stdout, "%s%.66s", test_info.failed ? "\n" : "", buf );
             mbedtls_fprintf( stdout, " " );
             for( i = strlen( buf ) + 1; i < 67; i++ )
                 mbedtls_fprintf( stdout, "." );
@@ -396,11 +412,11 @@
                     break;
                 cnt = parse_arguments( buf, strlen(buf), params );
             }
- 
+
             // If there are no unmet dependencies execute the test
             if( unmet_dep_count == 0 )
             {
-                test_errors = 0;
+                test_info.failed = 0;
 
 #if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
                 /* Suppress all output from the library unless we're verbose
@@ -454,9 +470,20 @@
 
                 unmet_dep_count = 0;
             }
-            else if( ret == DISPATCH_TEST_SUCCESS && test_errors == 0 )
+            else if( ret == DISPATCH_TEST_SUCCESS )
             {
-                mbedtls_fprintf( stdout, "PASS\n" );
+                if( test_info.failed == 0 )
+                {
+                    mbedtls_fprintf( stdout, "PASS\n" );
+                }
+                else
+                {
+                    total_errors++;
+                    mbedtls_fprintf( stdout, "FAILED\n" );
+                    mbedtls_fprintf( stdout, "  %s\n  at line %d, %s\n",
+                                     test_info.test, test_info.line_no,
+                                     test_info.filename );
+                }
                 fflush( stdout );
             }
             else if( ret == DISPATCH_INVALID_TEST_DATA )
diff --git a/tests/suites/test_suite_md.data b/tests/suites/test_suite_md.data
index 71d1f6d..abd8e55 100644
--- a/tests/suites/test_suite_md.data
+++ b/tests/suites/test_suite_md.data
@@ -1,3 +1,4 @@
+# Tests of the generic message digest interface
 MD process
 mbedtls_md_process:
 
diff --git a/tests/suites/test_suite_mdx.data b/tests/suites/test_suite_mdx.data
index 2d403b4..3d063a4 100644
--- a/tests/suites/test_suite_mdx.data
+++ b/tests/suites/test_suite_mdx.data
@@ -1,3 +1,4 @@
+# Test MD2, MD4, MD5 and RIPEMD160
 mbedtls_md2 Test vector RFC1319 #1
 md2_text:"":"8350e5a3e24c153df2275c9f80692773"
 
diff --git a/tests/suites/test_suite_rsa.data b/tests/suites/test_suite_rsa.data
index 5013ac8..fc7d935 100644
--- a/tests/suites/test_suite_rsa.data
+++ b/tests/suites/test_suite_rsa.data
@@ -1,5 +1,6 @@
 RSA PKCS1 Verify v1.5 CAVS #1
 depends_on:MBEDTLS_SHA1_C:MBEDTLS_PKCS1_V15
+# Good padding but wrong hash
 mbedtls_rsa_pkcs1_verify:"d6248c3e96b1a7e5fea978870fcc4c9786b4e5156e16b7faef4557d667f730b8bc4c784ef00c624df5309513c3a5de8ca94c2152e0459618666d3148092562ebc256ffca45b27fd2d63c68bd5e0a0aefbe496e9e63838a361b1db6fc272464f191490bf9c029643c49d2d9cd08833b8a70b4b3431f56fb1eb55ccd39e77a9c92":MBEDTLS_RSA_PKCS_V15:MBEDTLS_MD_SHA1:1024:16:"e28a13548525e5f36dccb24ecb7cc332cc689dfd64012604c9c7816d72a16c3f5fcdc0e86e7c03280b1c69b586ce0cd8aec722cc73a5d3b730310bf7dfebdc77ce5d94bbc369dc18a2f7b07bd505ab0f82224aef09fdc1e5063234255e0b3c40a52e9e8ae60898eb88a766bdd788fe9493d8fd86bcdd2884d5c06216c65469e5":16:"3":"3203b7647fb7e345aa457681e5131777f1adc371f2fba8534928c4e52ef6206a856425d6269352ecbf64db2f6ad82397768cafdd8cd272e512d617ad67992226da6bc291c31404c17fd4b7e2beb20eff284a44f4d7af47fd6629e2c95809fa7f2241a04f70ac70d3271bb13258af1ed5c5988c95df7fa26603515791075feccd":MBEDTLS_ERR_RSA_VERIFY_FAILED
 
 RSA PKCS1 Verify v1.5 CAVS #2
@@ -24,6 +25,7 @@
 
 RSA PKCS1 Verify v1.5 CAVS #7
 depends_on:MBEDTLS_SHA512_C:MBEDTLS_PKCS1_V15
+# Bad padding after performing the public key operation
 mbedtls_rsa_pkcs1_verify:"d03f12276f6ba7545b8fce719471bd253791878809694e8754f3b389f26c9253a758ed28b4c62535a8d5702d7a778731d5759ff2b3b39b192db680e791632918b6093c0e8ca25c2bf756a07fde4144a37f769fe4054455a45cb8cefe4462e7a9a45ce71f2189b4fef01b47aee8585d44dc9d6fa627a3e5f08801871731f234cd":MBEDTLS_RSA_PKCS_V15:MBEDTLS_MD_SHA384:1024:16:"e28a13548525e5f36dccb24ecb7cc332cc689dfd64012604c9c7816d72a16c3f5fcdc0e86e7c03280b1c69b586ce0cd8aec722cc73a5d3b730310bf7dfebdc77ce5d94bbc369dc18a2f7b07bd505ab0f82224aef09fdc1e5063234255e0b3c40a52e9e8ae60898eb88a766bdd788fe9493d8fd86bcdd2884d5c06216c65469e5":16:"3":"d93a878c1ce86571590b0e43794b3edb23552797c4b8c9e3da4fe1cc4ac0566acd3b10541fe9a7a79f5ea4892d3069ca6903efb5c40c47eb8a9c781eb4249281d40c3d96aae16da1bb4daaece6a26eca5f41c062b4124a64fc9d340cba5ab0d1f5affff6515a87f0933774fd4322d2fa497cd6f708a429ca56dcb1fd3db623d0":MBEDTLS_ERR_RSA_INVALID_PADDING
 
 RSA PKCS1 Verify v1.5 CAVS #8
@@ -365,6 +367,7 @@
 mbedtls_rsa_gen_key:2048:3:0
 
 RSA Generate Key - 1025 bit key
+# mbedtls_rsa_gen_key only supports even-sized keys
 mbedtls_rsa_gen_key:1025:3:MBEDTLS_ERR_RSA_BAD_INPUT_DATA
 
 RSA PKCS1 Encrypt Bad RNG
diff --git a/tests/suites/test_suite_shax.data b/tests/suites/test_suite_shax.data
index ea2a183..ee8074d 100644
--- a/tests/suites/test_suite_shax.data
+++ b/tests/suites/test_suite_shax.data
@@ -1,3 +1,4 @@
+# Test the operation of SHA-1 and SHA-2
 SHA-1 Test Vector NIST CAVS #1
 depends_on:MBEDTLS_SHA1_C
 mbedtls_sha1:"":"da39a3ee5e6b4b0d3255bfef95601890afd80709"
diff --git a/tests/suites/test_suite_ssl.data b/tests/suites/test_suite_ssl.data
index a39f6f0..b92c1fe 100644
--- a/tests/suites/test_suite_ssl.data
+++ b/tests/suites/test_suite_ssl.data
@@ -54,3 +54,6 @@
 
 SSL DTLS replay: big jump then just delayed
 ssl_dtls_replay:"abcd12340000,abcd12340100":"abcd123400ff":0
+
+SSL SET_HOSTNAME memory leak: call ssl_set_hostname twice
+ssl_set_hostname_twice:"server0":"server1"
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 8d3448c..60683af 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -40,3 +40,16 @@
     mbedtls_ssl_config_free( &conf );
 }
 /* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C */
+void ssl_set_hostname_twice( char *hostname0, char *hostname1 )
+{
+    mbedtls_ssl_context ssl;
+    mbedtls_ssl_init( &ssl );
+
+    TEST_ASSERT( mbedtls_ssl_set_hostname( &ssl, hostname0 ) == 0 );
+    TEST_ASSERT( mbedtls_ssl_set_hostname( &ssl, hostname1 ) == 0 );
+
+    mbedtls_ssl_free( &ssl );
+}
+/* END_CASE */
\ No newline at end of file
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index b8c902e..d4cc11a 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -1670,3 +1670,18 @@
 depends_on:MBEDTLS_X509_USE_C
 x509_get_time:MBEDTLS_ASN1_UTC_TIME:"0011302359n0Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0
 
+X509 Get time (Generalized Time, year multiple of 100 but not 400 is not a leap year)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_GENERALIZED_TIME:"19000229000000Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0
+
+X509 Get time (Generalized Time, year multiple of 4 but not 100 is a leap year)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_GENERALIZED_TIME:"19920229000000Z":0:1992:2:29:0:0:0
+
+X509 Get time (Generalized Time, year multiple of 400 is a leap year)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_GENERALIZED_TIME:"20000229000000Z":0:2000:2:29:0:0:0
+
+X509 Get time (Generalized Time invalid leap year not multiple of 4, 100 or 400)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_GENERALIZED_TIME:"19910229000000Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0