Merge mbedtls 2.16.6 into baremetal

Conflicts:
mbedtls.doxyfile - PROJECT_NAME - mbed TLS v2.16.6 chosen.
doc_mainpage.h - mbed TLS v2.16.6 version chosen.
hmac_drbg.h - line 260, extended description chosen.
            - line 313, extended description chosen.
            - line 338, extended description chosen.
version.h - 2.16.6 chosen.
CMakeLists.txt - 2.16.6 chosen.
test_suite_version.data - 2.16.6 chosen.
Makefile - 141 - manual correction - baremetal version of C_SOURCE_FILES
                 with variables for directories plus 2.16.6 CTAGS addition.
pkparse.c - lines 846 onwards - the asn1_get_nonzero_mpi implementation chosen.
ssl_tls.c - line 5269 - edited manually, left the ret=0, because baremetal has
            a different behaviour since commit 87b5626, but added a debug
            message that's new in 2.16.6.    
all.sh:
- component_build_deprecated - chosen the refactored version from 2.16.6,
                               but with extra flags from baremetal.
- rest of the _no_xxx tests - merged make options to have PTHREAD=1 and
                              other changes from 2.16.6 (like -O1 instead of -O0).
- component_build_arm_none_eabi_gcc_no_64bit_multiplication - added 
                              TINYCRYPT_BUILD=0 to the 2.16.6 version of make.

x509/req_app.c - left baremetal log but with mbedtls_exit( 0 ) call.
x509/crl_app.c - left baremetal log but with mbedtls_exit( 0 ) call.
x509/cert_app.c - left baremetal log but with mbedtls_exit( 0 ) call.
ssl/ssl_mail_client.c - left baremetal log but with mbedtls_exit( 0 ) call.
ssl/ssl_pthread_server.c - left baremetal log but with mbedtls_exit( 0 ) call.
ssl/ssl_fork_server.c - left baremetal log but with mbedtls_exit( 0 ) call.
ssl_client1.c - line 54 - left baremetal log but with mbedtls_exit( 0 ) call.
ssl_client2.c - line 54 - left baremetal log but with mbedtls_exit( 0 ) call.
              - line 132 - new options of both branches added.
              - skip close notify handled as in 2.16.6, but with `ssl` instead of `&ssl`.
              - Merged the 2.16.6 usage split with additional baremetal usages.
              - Merged options from baremetal and 2.16.6.
ssl_server.c - left baremetal log but with mbedtls_exit( 0 ) call.
ssl_server2.c - Merged the 2.16.6 usage split with additional baremetal usages.
config.pl - fixed missing defines from the documentation, removed duplicates,
            and reorganised so that the documentation and excluded list
            are ordered in the same way.
test_suite_x509parse.data - only added the two new pathlen tests.
x509_crt.c - change the return code by removing
             MBEDTLS_ERR_X509_INVALID_EXTENSIONS, since it's added by
             x509_crt_frame_parse_ext not by an "or", but by "+=".
Changelog - Assigned all entries to appropriate sections.
ssl-opt.sh - line 8263 - merged options.
           - removed lines 1165 - 1176 - there was a duplicate test, probably
             an artifact of previous merges.
check-files.py - sticked to old formatting.

Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index 207b0a2..3bf9e62 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -53,7 +53,7 @@
            "MBEDTLS_SSL_TLS_C and/or MBEDTLS_SSL_CLI_C and/or "
            "MBEDTLS_NET_C not defined, or "
            "neither MBEDTLS_CTR_DRBG_C nor MBEDTLS_HMAC_DRBG_C defined.\n");
-    return( 0 );
+    mbedtls_exit( 0 );
 }
 #else
 
@@ -131,6 +131,7 @@
 #define DFL_ETM                 -1
 #define DFL_SERIALIZE           0
 #define DFL_EXTENDED_MS_ENFORCE -1
+#define DFL_SKIP_CLOSE_NOTIFY   0
 
 #define GET_REQUEST "GET %s HTTP/1.0\r\nExtra-header: "
 #define GET_REQUEST_END "\r\n\r\n"
@@ -335,7 +336,9 @@
 #define USAGE_FORCE_VERSION ""
 #endif
 
-#define USAGE \
+/* USAGE is arbitrarily split to stay under the portable string literal
+ * length limit: 4095 bytes in C99. */
+#define USAGE1 \
     "\n usage: ssl_client2 param=<>...\n"                   \
     "\n acceptable parameters:\n"                           \
     "    server_name=%%s      default: localhost\n"         \
@@ -355,17 +358,22 @@
     "                        options: 1 (level-triggered, implies nbio=1),\n" \
     USAGE_READ_TIMEOUT                                                  \
     "    max_resend=%%d       default: 0 (no resend on timeout)\n" \
+    "    skip_close_notify=%%d default: 0 (send close_notify)\n" \
     "\n"                                                    \
     USAGE_DTLS                                              \
     USAGE_CID                                               \
-    "\n"                                                    \
+    "\n"
+
+#define USAGE2 \
     USAGE_AUTH_MODE                                         \
     USAGE_IO                                                \
     "\n"                                                    \
     USAGE_PSK                                               \
     USAGE_ECJPAKE                                           \
     USAGE_ECRESTART                                         \
-    "\n"                                                    \
+    "\n"
+
+#define USAGE3 \
     USAGE_ALLOW_LEGACY_RENEGO                               \
     USAGE_RENEGO                                            \
     "    exchanges=%%d        default: 1\n"                 \
@@ -385,7 +393,8 @@
     USAGE_CURVES                                            \
     USAGE_RECSPLIT                                          \
     USAGE_DHMLEN                                            \
-    "\n"                                                    \
+    "\n"
+#define USAGE4 \
     "    arc4=%%d             default: (library default: 0)\n" \
     "    allow_sha1=%%d       default: 0\n"                             \
     USAGE_MIN_VERSION                                                   \
@@ -466,6 +475,7 @@
     int serialize;              /* serialize/deserialize connection         */
     const char *cid_val_renego; /* the CID to use for incoming messages
                                  * after renegotiation                      */
+    int skip_close_notify;      /* skip sending the close_notify alert      */
 } opt;
 
 int query_config( const char *config );
@@ -1060,7 +1070,10 @@
         if( ret == 0 )
             ret = 1;
 
-        mbedtls_printf( USAGE );
+        mbedtls_printf( USAGE1 );
+        mbedtls_printf( USAGE2 );
+        mbedtls_printf( USAGE3 );
+        mbedtls_printf( USAGE4 );
 
         list = mbedtls_ssl_list_ciphersuites();
         while( *list )
@@ -1129,6 +1142,7 @@
     opt.etm                 = DFL_ETM;
     opt.dgram_packing       = DFL_DGRAM_PACKING;
     opt.serialize           = DFL_SERIALIZE;
+    opt.skip_close_notify   = DFL_SKIP_CLOSE_NOTIFY;
 
     for( i = 1; i < argc; i++ )
     {
@@ -1523,7 +1537,13 @@
         }
         else if( strcmp( p, "query_config" ) == 0 )
         {
-            return query_config( q );
+            mbedtls_exit( query_config( q ) );
+        }
+        else if( strcmp( p, "skip_close_notify" ) == 0 )
+        {
+            opt.skip_close_notify = atoi( q );
+            if( opt.skip_close_notify < 0 || opt.skip_close_notify > 1 )
+                goto usage;
         }
         else if( strcmp( p, "serialize") == 0 )
         {
@@ -2892,10 +2912,25 @@
     mbedtls_printf( "  . Closing the connection..." );
     fflush( stdout );
 
-    /* No error checking, the connection might be closed already */
-    do ret = mbedtls_ssl_close_notify( ssl );
-    while( ret == MBEDTLS_ERR_SSL_WANT_WRITE );
-    ret = 0;
+    /*
+     * Most of the time sending a close_notify before closing is the right
+     * thing to do. However, when the server already knows how many messages
+     * are expected and closes the connection by itself, this alert becomes
+     * redundant. Sometimes with DTLS this redundancy becomes a problem by
+     * leading to a race condition where the server might close the connection
+     * before seeing the alert, and since UDP is connection-less when the
+     * alert arrives it will be seen as a new connection, which will fail as
+     * the alert is clearly not a valid ClientHello. This may cause spurious
+     * failures in tests that use DTLS and resumption with ssl_server2 in
+     * ssl-opt.sh, avoided by enabling skip_close_notify client-side.
+     */
+    if( opt.skip_close_notify == 0 )
+    {
+        /* No error checking, the connection might be closed already */
+        do ret = mbedtls_ssl_close_notify( ssl );
+        while( ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+        ret = 0;
+    }
 
     mbedtls_printf( " done\n" );
 
@@ -3049,7 +3084,7 @@
     if( ret < 0 )
         ret = 1;
 
-    return( ret );
+    mbedtls_exit( ret );
 }
 #endif /* MBEDTLS_BIGNUM_C && MBEDTLS_ENTROPY_C && MBEDTLS_SSL_TLS_C &&
           MBEDTLS_SSL_CLI_C && MBEDTLS_NET_C && MBEDTLS_RSA_C &&