Introduce new TLS error codes

Introduce new codes:
* MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION
* MBEDTLS_ERR_SSL_NO_APPLICATION_PROTOCOL

These are returned when the corresponding alert is raised.

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>

include/mbedtls/ssl.h

diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 95cf1fb..64f90fe 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -72,8 +72,8 @@
 #define MBEDTLS_ERR_SSL_NO_CIPHER_CHOSEN                  -0x7380  /**< The server has no ciphersuites in common with the client. */
 #define MBEDTLS_ERR_SSL_NO_RNG                            -0x7400  /**< No RNG was provided to the SSL module. */
 #define MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE             -0x7480  /**< No client certification received from the client, but required by the authentication mode. */
-/* NOTE: Error space gap */
-/* NOTE: Error space gap */
+#define MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION             -0x7500  /**< Client received an extended server hello containing an unsupported extension */
+#define MBEDTLS_ERR_SSL_NO_APPLICATION_PROTOCOL           -0x7580  /**< No ALPN protocols supported that the client advertises */
 #define MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED              -0x7600  /**< The own private key or pre-shared key is not set, but needed. */
 #define MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED                 -0x7680  /**< No CA Chain is set, but required to operate. */
 #define MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE                -0x7700  /**< An unexpected message was received from our peer. */

library/ssl_cli.c

diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index fc791d6..d588fcd 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1454,7 +1454,7 @@
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "CID extension unexpected" ) );
         mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                                         MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
-        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
     }
 
     if( len == 0 )
@@ -1509,7 +1509,7 @@
             ssl,
             MBEDTLS_SSL_ALERT_LEVEL_FATAL,
             MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
-        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+        return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
     }
 
     ((void) buf);

library/ssl_srv.c

diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index c41eff2..7e94102 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -749,7 +749,7 @@
     /* If we get there, no match was found */
     mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                             MBEDTLS_SSL_ALERT_MSG_NO_APPLICATION_PROTOCOL );
-    return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+    return( MBEDTLS_ERR_SSL_NO_APPLICATION_PROTOCOL );
 }
 #endif /* MBEDTLS_SSL_ALPN */