Handle websocket close frames

We interpret the close frames as closed transport, and therefore set 'error' to 'disconnected'. See code comments.

Handle websocket close frames
We interpret the close frames as closed transport, and therefore set 'error' to 'disconnected'. See code comments.
Wiebe Cazemier
1 parent e40fba1e
Showing 4 changed files with 45 additions and 5 deletions
iowrapper.cpp
iowrapper.h
utils.cpp
utils.h
@@ -406,11 +406,11 @@ ssize_t IoWrapper::readWebsocketAndOrSsl(int fd, void *buf, size_t nbytes, IoWra
             }
             else
             {
-                n = websocketBytesToReadBuffer(buf, nbytes);
+                n = websocketBytesToReadBuffer(buf, nbytes, error);
                 if (n > 0)
                     *error = IoWrapResult::Success;
-                else if (n == 0)
+                else if (n == 0 && *error != IoWrapResult::Disconnected)
                     *error = IoWrapResult::Wouldblock;
             }
         }
@@ -426,7 +426,7 @@ ssize_t IoWrapper::readWebsocketAndOrSsl(int fd, void *buf, size_t nbytes, IoWra
  * @param nbytes
  * @return
  */
-ssize_t IoWrapper::websocketBytesToReadBuffer(void *buf, const size_t nbytes)
+ssize_t IoWrapper::websocketBytesToReadBuffer(void *buf, const size_t nbytes, IoWrapResult *error)
 {
     const ssize_t targetBufMaxSize = nbytes;
     ssize_t nbytesRead = 0;
@@ -523,6 +523,8 @@ ssize_t IoWrapper::websocketBytesToReadBuffer(void *buf, const size_t nbytes)
             if (incompleteWebsocketRead.frame_bytes_left <= websocketPendingBytes.usedBytes())
             {
+                logger->logf(LOG_INFO, "Ponging websocket");
+
                 // Constructing a new temporary buffer because I need the reponse in one frame for writeAsMuchOfBufAsWebsocketFrame().
                 std::vector<char> response(incompleteWebsocketRead.frame_bytes_left);
                 websocketPendingBytes.read(response.data(), response.size());
@@ -532,11 +534,35 @@ ssize_t IoWrapper::websocketBytesToReadBuffer(void *buf, const size_t nbytes)
                 parentClient->setReadyForWriting(true);
             }
         }
+        else if (incompleteWebsocketRead.opcode == WebsocketOpcode::Close)
+        {
+            // MUST be a 2-byte unsigned integer (in network byte order) representing a status code with value /code/ defined
+            if (incompleteWebsocketRead.frame_bytes_left <= websocketPendingBytes.usedBytes()
+                && incompleteWebsocketRead.frame_bytes_left >= 2)
+            {
+                const uint8_t msb = *websocketPendingBytes.tailPtr() ^ incompleteWebsocketRead.getNextMaskingByte();
+                websocketPendingBytes.advanceTail(1);
+                const uint8_t lsb = *websocketPendingBytes.tailPtr() ^ incompleteWebsocketRead.getNextMaskingByte();
+                websocketPendingBytes.advanceTail(1);
+
+                const uint16_t code = msb << 8 | lsb;
+
+                // An actual MQTT disconnect doesn't send websocket close frames, or perhaps after the MQTT
+                // disconnect when it doesn't matter anymore. So, when users close the tab or stuff like that,
+                // we can consider it a closed transport i.e. failed connection. This means will messages
+                // will be sent.
+                parentClient->setDisconnectReason(websocketCloseCodeToString(code));
+                *error = IoWrapResult::Disconnected;
+
+                // There may be a UTF8 string with a reason in the packet still, but ignoring that for now.
+                incompleteWebsocketRead.reset();
+            }
+        }
         else
         {
             // Specs: "MQTT Control Packets MUST be sent in WebSocket binary data frames. If any other type of data frame is
             // received the recipient MUST close the Network Connection [MQTT-6.0.0-1]".
-            throw ProtocolError("Websocket frames must be 'binary' or 'ping'");
+            throw ProtocolError(formatString("Websocket frames must be 'binary' or 'ping'. Received: %d", incompleteWebsocketRead.opcode));
         }
         if (!incompleteWebsocketRead.sillWorkingOnFrame())
@@ -115,7 +115,7 @@ class IoWrapper
     Logger *logger = Logger::getInstance();
-    ssize_t websocketBytesToReadBuffer(void *buf, const size_t nbytes);
+    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);
@@ -633,3 +633,15 @@ std::string sockaddrToString(sockaddr *addr)
     return "[unknown address]";
 }
+
+const std::string websocketCloseCodeToString(uint16_t code)
+{
+    switch (code) {
+    case 1000:
+        return "Normal websocket close";
+    case 1001:
+        return "Browser navigating away from page";
+    default:
+        return formatString("Websocket status code %d", code);
+    }
+}
@@ -122,5 +122,7 @@ template&lt;typename ex&gt; void checkWritableDir(const std::string &amp;path)
     }
 }
+const std::string websocketCloseCodeToString(uint16_t code);
+
 #endif // UTILS_H