Merge remote-tracking branch 'origin/pr/2803' into development

* origin/pr/2803:
  Add a ChangeLog entry for mbedtls_net_close()
  Added mbedtls_net_close and use it in ssl_fork_server to correctly disassociate the client socket from the parent process and the server socket from the child process.

ChangeLog

@@ -18,6 +18,10 @@ Features
      verified and significantly faster, but is only supported on x86 platforms
      (32-bit and 64-bit) using GCC, Clang or Visual Studio. Contributed by
      Christoph Wintersteiger from Microsoft Research.
+   * Add mbedtls_net_close(), enabling the building of forking servers where
+     the parent process closes the client socket and continue accepting, and
+     the child process closes the listening socket and handles the client
+     socket. Contributed by Robert Larsen in #2803.
 
 API Changes
    * Add DER-encoded test CRTs to library/certs.c, allowing

include/mbedtls/net_sockets.h

@@ -257,6 +257,13 @@ int mbedtls_net_send( void *ctx, const unsigned char *buf, size_t len );
 int mbedtls_net_recv_timeout( void *ctx, unsigned char *buf, size_t len,
                       uint32_t timeout );
 
+/**
+ * \brief          Closes down the connection and free associated data
+ *
+ * \param ctx      The context to close
+ */
+void mbedtls_net_close( mbedtls_net_context *ctx );
+
 /**
  * \brief          Gracefully shutdown the connection and free associated data
  *

library/net_sockets.c

@@ -651,6 +651,19 @@ int mbedtls_net_send( void *ctx, const unsigned char *buf, size_t len )
     return( ret );
 }
 
+/*
+ * Close the connection
+ */
+void mbedtls_net_close( mbedtls_net_context *ctx )
+{
+    if( ctx->fd == -1 )
+        return;
+
+    close( ctx->fd );
+
+    ctx->fd = -1;
+}
+
 /*
  * Gracefully close the connection
  */

programs/ssl/ssl_fork_server.c

@@ -254,6 +254,7 @@ int main( void )
         if( pid != 0 )
         {
             mbedtls_printf( " ok\n" );
+            mbedtls_net_close( &client_fd );
 
             if( ( ret = mbedtls_ctr_drbg_reseed( &ctr_drbg,
                                          (const unsigned char *) "parent",
@@ -266,7 +267,7 @@ int main( void )
             continue;
         }
 
-        mbedtls_net_init( &listen_fd );
+        mbedtls_net_close( &listen_fd );
 
         pid = getpid();