Increase WebSocket frame size and improve large read handling
authorDavid M. Lee <dlee@digium.com>
Wed, 25 Feb 2015 20:47:39 +0000 (20:47 +0000)
committerDavid M. Lee <dlee@digium.com>
Wed, 25 Feb 2015 20:47:39 +0000 (20:47 +0000)
Some WebSocket applications, like [chan_respoke][], require a larger
frame size than the default 8k; this patch bumps the default to 16k.
This patch also fixes some problems exacerbated by large frames.

The sanity counter was decremented on every fread attempt in
ws_safe_read(), regardless of whether data was read from the socket or
not. For large frames, this could result in loss of sanity prior to
reading the entire frame. (16k frame / 1448 bytes per segment = 12
segments).

This patch changes the sanity counter so that it only decrements when
fread() doesn't read any bytes. This more closely matches the original
intention of ws_safe_read(), given that the error message is
"Websocket seems unresponsive".

This patch also properly logs EOF conditions, so disconnects are no
longer confused with unresponsive connections.

 [chan_respoke]: https://github.com/respoke/chan_respoke

Review: https://reviewboard.asterisk.org/r/4431/
........

Merged revisions 432236 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 432237 from http://svn.asterisk.org/svn/asterisk/branches/13

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@432238 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_http_websocket.c

index d1beae6..7e71f8b 100644 (file)
@@ -52,7 +52,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #define MAX_PROTOCOL_BUCKETS 7
 
 /*! \brief Size of the pre-determined buffer for WebSocket frames */
-#define MAXIMUM_FRAME_SIZE 8192
+#define MAXIMUM_FRAME_SIZE 16384
 
 /*! \brief Default reconstruction size for multi-frame payload reconstruction. If exceeded the next frame will start a
  *         payload.
@@ -413,18 +413,35 @@ int AST_OPTIONAL_API_NAME(ast_websocket_set_timeout)(struct ast_websocket *sessi
  */
 static inline int ws_safe_read(struct ast_websocket *session, char *buf, int len, enum ast_websocket_opcode *opcode)
 {
-       int sanity;
        size_t rlen;
        int xlen = len;
        char *rbuf = buf;
-       for (sanity = 10; sanity; sanity--) {
+       int sanity = 10;
+
+       for (;;) {
                clearerr(session->f);
                rlen = fread(rbuf, 1, xlen, session->f);
-               if (!rlen && ferror(session->f) && errno != EAGAIN) {
-                       ast_log(LOG_ERROR, "Error reading from web socket: %s\n", strerror(errno));
-                       *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
-                       session->closing = 1;
-                       return -1;
+               if (!rlen) {
+                       if (feof(session->f)) {
+                               ast_log(LOG_WARNING, "Web socket closed abruptly\n");
+                               *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
+                               session->closing = 1;
+                               return -1;
+                       }
+
+                       if (ferror(session->f) && errno != EAGAIN) {
+                               ast_log(LOG_ERROR, "Error reading from web socket: %s\n", strerror(errno));
+                               *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
+                               session->closing = 1;
+                               return -1;
+                       }
+
+                       if (!--sanity) {
+                               ast_log(LOG_WARNING, "Websocket seems unresponsive, disconnecting ...\n");
+                               *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
+                               session->closing = 1;
+                               return -1;
+                       }
                }
                xlen = xlen - rlen;
                rbuf = rbuf + rlen;
@@ -438,12 +455,6 @@ static inline int ws_safe_read(struct ast_websocket *session, char *buf, int len
                        return -1;
                }
        }
-       if (!sanity) {
-               ast_log(LOG_WARNING, "Websocket seems unresponsive, disconnecting ...\n");
-               *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
-               session->closing = 1;
-               return -1;
-       }
        return 0;
 }