Websocket en-/decoding

- state is fully kept at connection, since curl_ws_send() and
  curl_ws_rec() have lifetime beyond usual transfers
- no more limit on frame sizes

Reported-by: simplerobot on github
Fixes #10962
Closes #10999

lib/easy.c

@@ -1223,6 +1223,26 @@ CURLcode curl_easy_recv(struct Curl_easy *data, void *buffer, size_t buflen,
   return CURLE_OK;
 }
 
+#ifdef USE_WEBSOCKETS
+CURLcode Curl_connect_only_attach(struct Curl_easy *data)
+{
+  curl_socket_t sfd;
+  CURLcode result;
+  struct connectdata *c = NULL;
+
+  result = easy_connection(data, &sfd, &c);
+  if(result)
+    return result;
+
+  if(!data->conn)
+    /* on first invoke, the transfer has been detached from the connection and
+       needs to be reattached */
+    Curl_attach_connection(data, c);
+
+  return CURLE_OK;
+}
+#endif /* USE_WEBSOCKETS */
+
 /*
  * Sends data over the connected socket.
  *

lib/easyif.h

@@ -30,6 +30,10 @@
 CURLcode Curl_senddata(struct Curl_easy *data, const void *buffer,
                        size_t buflen, ssize_t *n);
 
+#ifdef USE_WEBSOCKETS
+CURLcode Curl_connect_only_attach(struct Curl_easy *data);
+#endif
+
 #ifdef CURLDEBUG
 CURL_EXTERN CURLcode curl_easy_perform_ev(struct Curl_easy *easy);
 #endif

lib/http.h

@@ -212,10 +212,6 @@ struct HTTP {
     HTTPSEND_BODY     /* sending body */
   } sending;
 
-#ifdef USE_WEBSOCKETS
-  struct websocket ws;
-#endif
-
 #ifndef CURL_DISABLE_HTTP
   void *h2_ctx;              /* HTTP/2 implementation context */
   void *h3_ctx;              /* HTTP/3 implementation context */

lib/sendf.c

@@ -271,10 +271,8 @@ static CURLcode chop_write(struct Curl_easy *data,
   if(type & CLIENTWRITE_BODY) {
 #ifdef USE_WEBSOCKETS
     if(conn->handler->protocol & (CURLPROTO_WS|CURLPROTO_WSS)) {
-      struct HTTP *ws = data->req.p.http;
       writebody = Curl_ws_writecb;
-      ws->ws.data = data;
-      writebody_ptr = ws;
+      writebody_ptr = data;
     }
     else
 #endif

lib/urldata.h

@@ -1030,7 +1030,7 @@ struct connectdata {
     struct mqtt_conn mqtt;
 #endif
 #ifdef USE_WEBSOCKETS
-    struct ws_conn ws;
+    struct websocket *ws;
 #endif
   } proto;
 

lib/ws.h

@@ -33,28 +33,44 @@
 #define REQTYPE struct dynbuf
 #endif
 
-/* this is the largest single fragment size we support */
-#define MAX_WS_SIZE 65535
-
-/* part of 'struct HTTP', when used in the 'struct SingleRequest' in the
-   Curl_easy struct */
-struct websocket {
-  bool contfragment; /* set TRUE if the previous fragment sent was not final */
-  unsigned char mask[4]; /* 32 bit mask for this connection */
-  struct Curl_easy *data; /* used for write callback handling */
-  struct dynbuf buf;
-  size_t usedbuf; /* number of leading bytes in 'buf' the most recent complete
-                     websocket frame uses */
-  struct curl_ws_frame frame; /* the struct used for frame state */
-  size_t stillblen; /* number of bytes left in the buffer to deliver in
-                         the next curl_ws_recv() call */
-  const char *stillb; /* the stillblen pending bytes are here */
-  curl_off_t sleft; /* outstanding number of payload bytes left to send */
-  unsigned int xori; /* xor index */
+/* a client-side WS frame decoder, parsing frame headers and
+ * payload, keeping track of current position and stats */
+enum ws_dec_state {
+  WS_DEC_INIT,
+  WS_DEC_HEAD,
+  WS_DEC_PAYLOAD
 };
 
-struct ws_conn {
-  struct dynbuf early; /* data already read when switching to ws */
+struct ws_decoder {
+  int frame_age;        /* zero */
+  int frame_flags;      /* See the CURLWS_* defines */
+  curl_off_t payload_offset;   /* the offset parsing is at */
+  curl_off_t payload_len;
+  unsigned char head[10];
+  int head_len, head_total;
+  enum ws_dec_state state;
+};
+
+/* a client-side WS frame encoder, generating frame headers and
+ * converting payloads, tracking remaining data in current frame */
+struct ws_encoder {
+  curl_off_t payload_len;  /* payload length of current frame */
+  curl_off_t payload_remain;  /* remaining payload of current */
+  unsigned int xori; /* xor index */
+  unsigned char mask[4]; /* 32 bit mask for this connection */
+  unsigned char firstbyte; /* first byte of frame we encode */
+  bool contfragment; /* set TRUE if the previous fragment sent was not final */
+};
+
+/* A websocket connection with en- and decoder that treat frames
+ * and keep track of boundaries. */
+struct websocket {
+  struct Curl_easy *data; /* used for write callback handling */
+  struct ws_decoder dec;  /* decode of we frames */
+  struct ws_encoder enc;  /* decode of we frames */
+  struct bufq recvbuf;    /* raw data from the server */
+  struct bufq sendbuf;    /* raw data to be sent to the server */
+  struct curl_ws_frame frame;  /* the current WS FRAME received */
 };
 
 CURLcode Curl_ws_request(struct Curl_easy *data, REQTYPE *req);

tests/libtest/lib2304.c

@@ -67,6 +67,20 @@ static int recv_pong(CURL *curl, const char *exected_payload)
   return (int)result;
 }
 
+static int recv_any(CURL *curl)
+{
+  size_t rlen;
+  struct curl_ws_frame *meta;
+  char buffer[256];
+  CURLcode result = curl_ws_recv(curl, buffer, sizeof(buffer), &rlen, &meta);
+  if(result)
+    return result;
+
+  fprintf(stderr, "recv_any: got %u bytes rflags %x\n", (int)rlen,
+          meta->flags);
+  return 0;
+}
+
 /* just close the connection */
 static void websocket_close(CURL *curl)
 {
@@ -82,6 +96,7 @@ static void websocket(CURL *curl)
   int i = 0;
   fprintf(stderr, "ws: websocket() starts\n");
   do {
+    recv_any(curl);
     fprintf(stderr, "Send ping\n");
     if(ping(curl, "foobar"))
       return;