Fix length bug in sending websocket frames

One part is a fix, where the frame was advertised to be bigger than it was. The other change is making it possible to send chunks larger than the initial buffer size, by resizing the buffer (and resetting it later).

Fix length bug in sending websocket frames
One part is a fix, where the frame was advertised to be bigger than it was. The other change is making it possible to send chunks larger than the initial buffer size, by resizing the buffer (and resetting it later).
Wiebe Cazemier
1 parent 67df67f0
Showing 3 changed files with 18 additions and 8 deletions
client.cpp
iowrapper.cpp
iowrapper.h
@@ -315,6 +315,7 @@ std::string Client::getKeepAliveInfoString() const
 void Client::resetBuffersIfEligible()
 {
     readbuf.resetSizeIfEligable(initialBufferSize);
+    ioWrapper.resetBuffersIfEligible();
     // Write buffers are written to from other threads, and this resetting takes place from the Client's own thread, so we need to lock.
     std::lock_guard<std::mutex> locker(writeBufMutex);
@@ -579,27 +579,28 @@ ssize_t IoWrapper::websocketBytesToReadBuffer(void *buf, const size_t nbytes, Io
  * @param nbytes. The amount of bytes. Can be 0, for just an empty websocket frame.
  * @return
  */
-ssize_t IoWrapper::writeAsMuchOfBufAsWebsocketFrame(const void *buf, size_t nbytes, WebsocketOpcode opcode)
+ssize_t IoWrapper::writeAsMuchOfBufAsWebsocketFrame(const void *buf, const size_t nbytes, WebsocketOpcode opcode)
 {
     // We do allow pong frames to generate a zero payload packet, but for binary, that's not necessary.
     if (nbytes == 0 && opcode == WebsocketOpcode::Binary)
         return 0;
-    ssize_t nBytesReal = 0;
+    websocketWriteRemainder.ensureFreeSpace(nbytes + WEBSOCKET_MAX_SENDING_HEADER_SIZE, 131072);
+    const ssize_t nBytesReal = std::min<size_t>(nbytes, websocketWriteRemainder.freeSpace() - WEBSOCKET_MAX_SENDING_HEADER_SIZE);
     // We normally wrap each write in a frame, but if a previous one didn't fit in the system's write buffers, we're still working on it.
     if (websocketWriteRemainder.freeSpace() > WEBSOCKET_MAX_SENDING_HEADER_SIZE)
     {
         uint8_t extended_payload_length_num_bytes = 0;
         uint8_t payload_length = 0;
-        if (nbytes < 126)
-            payload_length = nbytes;
-        else if (nbytes >= 126 && nbytes <= 0xFFFF)
+        if (nBytesReal < 126)
+            payload_length = nBytesReal;
+        else if (nBytesReal >= 126 && nBytesReal <= 0xFFFF)
         {
             payload_length = 126;
             extended_payload_length_num_bytes = 2;
         }
-        else if (nbytes > 0xFFFF)
+        else if (nBytesReal > 0xFFFF)
         {
             payload_length = 127;
             extended_payload_length_num_bytes = 8;
@@ -613,7 +614,6 @@ ssize_t IoWrapper::writeAsMuchOfBufAsWebsocketFrame(const void *buf, size_t nbyt
         const int header_length = x + extended_payload_length_num_bytes;
         // This block writes the extended payload length.
-        nBytesReal = std::min<size_t>(nbytes, websocketWriteRemainder.freeSpace() - header_length);
         const uint64_t nbytes64 = nBytesReal;
         for (int z = extended_payload_length_num_bytes - 1; z >= 0; z--)
         {
@@ -667,3 +667,10 @@ ssize_t IoWrapper::writeWebsocketAndOrSsl(int fd, const void *buf, size_t nbytes
         return n;
     }
 }
+
+void IoWrapper::resetBuffersIfEligible()
+{
+    const size_t sz = websocket ? initialBufferSize : 0;
+    websocketPendingBytes.resetSizeIfEligable(sz),
+    websocketWriteRemainder.resetSizeIfEligable(sz);
+}
@@ -118,7 +118,7 @@ class IoWrapper
     ssize_t websocketBytesToReadBuffer(void *buf, const size_t nbytes, IoWrapResult *error);
     ssize_t readOrSslRead(int fd, void *buf, size_t nbytes, IoWrapResult *error);
     ssize_t writeOrSslWrite(int fd, const void *buf, size_t nbytes, IoWrapResult *error);
-    ssize_t writeAsMuchOfBufAsWebsocketFrame(const void *buf, size_t nbytes, WebsocketOpcode opcode = WebsocketOpcode::Binary);
+    ssize_t writeAsMuchOfBufAsWebsocketFrame(const void *buf, const size_t nbytes, WebsocketOpcode opcode = WebsocketOpcode::Binary);
 public:
     IoWrapper(SSL *ssl, bool websocket, const size_t initialBufferSize, Client *parent);
     ~IoWrapper();
@@ -138,6 +138,8 @@ public:
     ssize_t readWebsocketAndOrSsl(int fd, void *buf, size_t nbytes, IoWrapResult *error);
     ssize_t writeWebsocketAndOrSsl(int fd, const void *buf, size_t nbytes, IoWrapResult *error);
+
+    void resetBuffersIfEligible();
 };
 #endif // IOWRAPPER_H