Merge pull request #3809 from AndrzejKurek/refactor-variable-buffers

Refactor variable I/O buffers feature to reduce code duplication

include/mbedtls/check_config.h

@@ -886,6 +886,10 @@
 #error "MBEDTLS_SSL_DTLS_SRTP defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH) && ( !defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) )
+#error "MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH defined, but not all prerequisites"
+#endif
+
 /*
  * Avoid warning from -pedantic. This is a convenient place for this
  * workaround since this is included by every single file before the

include/mbedtls/config.h

@@ -1979,7 +1979,10 @@
 /**
  * \def MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH
  *
- * Enable modifying the maximum I/O buffer size.
+ * When this option is enabled, the SSL buffer will be resized automatically
+ * based on the negotiated maximum fragment length in each direction.
+ *
+ * Requires: MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
  */
 //#define MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH
 

include/mbedtls/ssl_internal.h

@@ -275,26 +275,26 @@
 #endif
 
 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
-static inline uint32_t mbedtls_ssl_get_output_buflen( const mbedtls_ssl_context *ctx )
+static inline size_t mbedtls_ssl_get_output_buflen( const mbedtls_ssl_context *ctx )
 {
 #if defined (MBEDTLS_SSL_DTLS_CONNECTION_ID)
-    return (uint32_t) mbedtls_ssl_get_output_max_frag_len( ctx )
+    return mbedtls_ssl_get_output_max_frag_len( ctx )
                + MBEDTLS_SSL_HEADER_LEN + MBEDTLS_SSL_PAYLOAD_OVERHEAD
                + MBEDTLS_SSL_CID_OUT_LEN_MAX;
 #else
-    return (uint32_t) mbedtls_ssl_get_output_max_frag_len( ctx )
+    return mbedtls_ssl_get_output_max_frag_len( ctx )
                + MBEDTLS_SSL_HEADER_LEN + MBEDTLS_SSL_PAYLOAD_OVERHEAD;
 #endif
 }
 
-static inline uint32_t mbedtls_ssl_get_input_buflen( const mbedtls_ssl_context *ctx )
+static inline size_t mbedtls_ssl_get_input_buflen( const mbedtls_ssl_context *ctx )
 {
 #if defined (MBEDTLS_SSL_DTLS_CONNECTION_ID)
-    return (uint32_t) mbedtls_ssl_get_input_max_frag_len( ctx )
+    return mbedtls_ssl_get_input_max_frag_len( ctx )
                + MBEDTLS_SSL_HEADER_LEN + MBEDTLS_SSL_PAYLOAD_OVERHEAD
                + MBEDTLS_SSL_CID_IN_LEN_MAX;
 #else
-    return (uint32_t) mbedtls_ssl_get_input_max_frag_len( ctx )
+    return mbedtls_ssl_get_input_max_frag_len( ctx )
                + MBEDTLS_SSL_HEADER_LEN + MBEDTLS_SSL_PAYLOAD_OVERHEAD;
 #endif
 }

library/ssl_tls.c

@@ -260,6 +260,70 @@ static int resize_buffer( unsigned char **buffer, size_t len_new, size_t *len_ol
 
     return 0;
 }
+
+static void handle_buffer_resizing( mbedtls_ssl_context *ssl, int downsizing,
+                                    size_t in_buf_new_len,
+                                    size_t out_buf_new_len )
+{
+    int modified = 0;
+    size_t written_in = 0, iv_offset_in = 0, len_offset_in = 0;
+    size_t written_out = 0, iv_offset_out = 0, len_offset_out = 0;
+    if( ssl->in_buf != NULL )
+    {
+        written_in = ssl->in_msg - ssl->in_buf;
+        iv_offset_in = ssl->in_iv - ssl->in_buf;
+        len_offset_in = ssl->in_len - ssl->in_buf;
+        if( downsizing ?
+            ssl->in_buf_len > in_buf_new_len && ssl->in_left < in_buf_new_len :
+            ssl->in_buf_len < in_buf_new_len )
+        {
+            if( resize_buffer( &ssl->in_buf, in_buf_new_len, &ssl->in_buf_len ) != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
+            }
+            else
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", in_buf_new_len ) );
+                modified = 1;
+            }
+        }
+    }
+
+    if( ssl->out_buf != NULL )
+    {
+        written_out = ssl->out_msg - ssl->out_buf;
+        iv_offset_out = ssl->out_iv - ssl->out_buf;
+        len_offset_out = ssl->out_len - ssl->out_buf;
+        if( downsizing ?
+            ssl->out_buf_len > out_buf_new_len && ssl->out_left < out_buf_new_len :
+            ssl->out_buf_len < out_buf_new_len )
+        {
+            if( resize_buffer( &ssl->out_buf, out_buf_new_len, &ssl->out_buf_len ) != 0 )
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
+            }
+            else
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", out_buf_new_len ) );
+                modified = 1;
+            }
+        }
+    }
+    if( modified )
+    {
+        /* Update pointers here to avoid doing it twice. */
+        mbedtls_ssl_reset_in_out_pointers( ssl );
+        /* Fields below might not be properly updated with record
+         * splitting or with CID, so they are manually updated here. */
+        ssl->out_msg = ssl->out_buf + written_out;
+        ssl->out_len = ssl->out_buf + len_offset_out;
+        ssl->out_iv = ssl->out_buf + iv_offset_out;
+
+        ssl->in_msg = ssl->in_buf + written_in;
+        ssl->in_len = ssl->in_buf + len_offset_in;
+        ssl->in_iv = ssl->in_buf + iv_offset_in;
+    }
+}
 #endif /* MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH */
 
 /*
@@ -3686,64 +3750,9 @@ static int ssl_handshake_init( mbedtls_ssl_context *ssl )
     }
 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
     /* If the buffers are too small - reallocate */
-    {
-        int modified = 0;
-        size_t written_in = 0, iv_offset_in = 0, len_offset_in = 0;
-        size_t written_out = 0, iv_offset_out = 0, len_offset_out = 0;
-        if( ssl->in_buf != NULL )
-        {
-            written_in = ssl->in_msg - ssl->in_buf;
-            iv_offset_in = ssl->in_iv - ssl->in_buf;
-            len_offset_in = ssl->in_len - ssl->in_buf;
-            if( ssl->in_buf_len < MBEDTLS_SSL_IN_BUFFER_LEN )
-            {
-                if( resize_buffer( &ssl->in_buf, MBEDTLS_SSL_IN_BUFFER_LEN,
-                                   &ssl->in_buf_len ) != 0 )
-                {
-                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
-                }
-                else
-                {
-                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", MBEDTLS_SSL_IN_BUFFER_LEN ) );
-                    modified = 1;
-                }
-            }
-        }
 
-        if( ssl->out_buf != NULL )
+    handle_buffer_resizing( ssl, 0, MBEDTLS_SSL_IN_BUFFER_LEN,
-        {
+                                    MBEDTLS_SSL_OUT_BUFFER_LEN );
-            written_out = ssl->out_msg - ssl->out_buf;
-            iv_offset_out = ssl->out_iv - ssl->out_buf;
-            len_offset_out = ssl->out_len - ssl->out_buf;
-            if( ssl->out_buf_len < MBEDTLS_SSL_OUT_BUFFER_LEN )
-            {
-                if( resize_buffer( &ssl->out_buf, MBEDTLS_SSL_OUT_BUFFER_LEN,
-                                   &ssl->out_buf_len ) != 0 )
-                {
-                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
-                }
-                else
-                {
-                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", MBEDTLS_SSL_OUT_BUFFER_LEN ) );
-                    modified = 1;
-                }
-            }
-        }
-        if( modified )
-        {
-            /* Update pointers here to avoid doing it twice. */
-            mbedtls_ssl_reset_in_out_pointers( ssl );
-            /* Fields below might not be properly updated with record
-             * splitting or with CID, so they are manually updated here. */
-            ssl->out_msg = ssl->out_buf + written_out;
-            ssl->out_len = ssl->out_buf + len_offset_out;
-            ssl->out_iv = ssl->out_buf + iv_offset_out;
-
-            ssl->in_msg = ssl->in_buf + written_in;
-            ssl->in_len = ssl->in_buf + len_offset_in;
-            ssl->in_iv = ssl->in_buf + iv_offset_in;
-        }
-    }
 #endif
 
     /* All pointers should exist and can be directly freed without issue */
@@ -6068,66 +6077,8 @@ void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
      * processes datagrams and the fact that a datagram is allowed to have
      * several records in it, it is possible that the I/O buffers are not
      * empty at this stage */
-    {
+    handle_buffer_resizing( ssl, 1, mbedtls_ssl_get_input_buflen( ssl ),
-        int modified = 0;
+                                    mbedtls_ssl_get_output_buflen( ssl ) );
-        uint32_t buf_len = mbedtls_ssl_get_input_buflen( ssl );
-        size_t written_in = 0, iv_offset_in = 0, len_offset_in = 0;
-        size_t written_out = 0, iv_offset_out = 0, len_offset_out = 0;
-        if( ssl->in_buf != NULL )
-        {
-            written_in = ssl->in_msg - ssl->in_buf;
-            iv_offset_in = ssl->in_iv - ssl->in_buf;
-            len_offset_in = ssl->in_len - ssl->in_buf;
-            if( ssl->in_buf_len > buf_len && ssl->in_left < buf_len )
-            {
-                if( resize_buffer( &ssl->in_buf, buf_len, &ssl->in_buf_len ) != 0 )
-                {
-                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
-                }
-                else
-                {
-                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", buf_len ) );
-                    modified = 1;
-                }
-            }
-        }
-
-
-        buf_len = mbedtls_ssl_get_output_buflen( ssl );
-        if(ssl->out_buf != NULL )
-        {
-            written_out = ssl->out_msg - ssl->out_buf;
-            iv_offset_out = ssl->out_iv - ssl->out_buf;
-            len_offset_out = ssl->out_len - ssl->out_buf;
-            if( ssl->out_buf_len > mbedtls_ssl_get_output_buflen( ssl ) &&
-                ssl->out_left < buf_len )
-            {
-                if( resize_buffer( &ssl->out_buf, buf_len, &ssl->out_buf_len ) != 0 )
-                {
-                    MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
-                }
-                else
-                {
-                    MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", buf_len ) );
-                    modified = 1;
-                }
-            }
-        }
-        if( modified )
-        {
-            /* Update pointers here to avoid doing it twice. */
-            mbedtls_ssl_reset_in_out_pointers( ssl );
-            /* Fields below might not be properly updated with record
-             * splitting or with CID, so they are manually updated here. */
-            ssl->out_msg = ssl->out_buf + written_out;
-            ssl->out_len = ssl->out_buf + len_offset_out;
-            ssl->out_iv = ssl->out_buf + iv_offset_out;
-
-            ssl->in_msg = ssl->in_buf + written_in;
-            ssl->in_len = ssl->in_buf + len_offset_in;
-            ssl->in_iv = ssl->in_buf + iv_offset_in;
-        }
-    }
 #endif
 }