ws: corrected curlws_cont to reflect its documented purpose

Verified in test 2311

Closes #16512

lib/ws.c

@@ -168,6 +168,7 @@ static void ws_dec_reset(struct ws_decoder *dec)
   dec->payload_len = 0;
   dec->head_len = dec->head_total = 0;
   dec->state = WS_DEC_INIT;
+  dec->fin_bit = TRUE;
 }
 
 static void ws_dec_init(struct ws_decoder *dec)
@@ -187,6 +188,8 @@ static CURLcode ws_dec_read_head(struct ws_decoder *dec,
       dec->head[0] = *inbuf;
       Curl_bufq_skip(inraw, 1);
 
+      dec->fin_bit = (dec->head[0] & WSBIT_FIN) ? TRUE : FALSE;
+
       if(!ws_frame_rsv_supported(dec->head[0])) {
         failf(data, "WS: unknown reserved bit in frame header: %x",
               dec->head[0] & WSBIT_RSV_MASK);
@@ -370,11 +373,20 @@ static void update_meta(struct websocket *ws,
                         curl_off_t payload_len,
                         size_t cur_len)
 {
+  curl_off_t bytesleft = (payload_len - payload_offset - cur_len);
+
   ws->frame.age = frame_age;
   ws->frame.flags = frame_flags;
   ws->frame.offset = payload_offset;
   ws->frame.len = cur_len;
-  ws->frame.bytesleft = (payload_len - payload_offset - cur_len);
+  ws->frame.bytesleft = bytesleft;
+
+  if(!ws->dec.fin_bit || bytesleft > 0) {
+    ws->frame.flags |= CURLWS_CONT;
+  }
+  else {
+    ws->frame.flags &= ~CURLWS_CONT;
+  }
 }
 
 /* WebSockets decoding client writer */

lib/ws.h

@@ -43,6 +43,7 @@ struct ws_decoder {
   unsigned char head[10];
   int head_len, head_total;
   enum ws_dec_state state;
+  bool fin_bit;
 };
 
 /* a client-side WS frame encoder, generating frame headers and

tests/data/Makefile.am

@@ -257,7 +257,7 @@ test2100 \
 test2200 test2201 test2202 test2203 test2204 test2205 \
 \
 test2300 test2301 test2302 test2303 test2304 test2305 test2306 test2307 \
-test2308 test2309 test2310 \
+test2308 test2309 test2310 test2311 \
 \
 test2400 test2401 test2402 test2403 test2404 test2405 test2406 \
 \

tests/data/test2311

@@ -0,0 +1,59 @@
+<testcase>
+<info>
+<keywords>
+WebSockets
+</keywords>
+</info>
+
+#
+# Sends three 4097 bytes TEXT frames, as one single message
+<reply>
+<data nocheck="yes">
+HTTP/1.1 101 Switching to WebSockets
+Server: test-server/fake
+Upgrade: websocket
+Connection: Upgrade
+Something: else
+Sec-WebSocket-Accept: HkPsVga7+8LuxM4RGQ5p9tZHeYs=
+
+%hex[%01%7e%10%01]hex%%repeat[256 x helothisisdaniel]%
+%hex[%01%7e%10%01]hex%%repeat[256 x helothisisdaniel]%
+%hex[%81%7e%10%01]hex%%repeat[256 x helothisisdaniel]%
+</data>
+# allow upgrade
+<servercmd>
+upgrade
+</servercmd>
+</reply>
+
+#
+# Client-side
+<client>
+# require debug for the forced CURL_ENTROPY
+<features>
+Debug
+ws
+</features>
+<server>
+http
+</server>
+<name>
+WebSocket curl_ws_recv() loop reading three larger frames
+</name>
+<tool>
+lib%TESTNUMBER
+</tool>
+<command>
+ws://%HOSTIP:%HTTPPORT/%TESTNUMBER %LOGDIR/save%TESTNUMBER
+</command>
+</client>
+
+#
+<verify>
+<file name="%LOGDIR/save%TESTNUMBER" mode="text">
+%repeat[256 x helothisisdaniel]%
+%repeat[256 x helothisisdaniel]%
+%repeat[256 x helothisisdaniel]%
+</file>
+</verify>
+</testcase>

tests/libtest/Makefile.inc

@@ -74,6 +74,7 @@ LIBTESTPROGS = libauthretry libntlmconnect libprereq                     \
  lib1960 lib1964 \
  lib1970 lib1971 lib1972 lib1973 lib1974 lib1975 lib1977 \
  lib2301 lib2302 lib2304 lib2305 lib2306         lib2308 lib2309 lib2310 \
+ lib2311 \
  lib2402 lib2404 lib2405 \
  lib2502 \
  lib3010 lib3025 lib3026 lib3027 \
@@ -703,6 +704,9 @@ lib2309_LDADD = $(TESTUTIL_LIBS)
 lib2310_SOURCES = lib2310.c $(SUPPORTFILES) $(TESTUTIL) $(TSTTRACE) $(MULTIBYTE)
 lib2310_LDADD = $(TESTUTIL_LIBS)
 
+lib2311_SOURCES = lib2311.c $(SUPPORTFILES) $(TESTUTIL) $(TSTTRACE) $(MULTIBYTE)
+lib2311_LDADD = $(TESTUTIL_LIBS)
+
 lib2402_SOURCES = lib2402.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
 lib2402_LDADD = $(TESTUTIL_LIBS)
 

tests/libtest/lib2311.c

@@ -0,0 +1,115 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * SPDX-License-Identifier: curl
+ *
+ ***************************************************************************/
+
+#include "test.h"
+#include "testtrace.h"
+#include "memdebug.h"
+
+#ifndef CURL_DISABLE_WEBSOCKETS
+
+/* just close the connection */
+static void websocket_close(CURL *curl)
+{
+  size_t sent;
+  CURLcode result =
+    curl_ws_send(curl, "", 0, &sent, 0, CURLWS_CLOSE);
+  fprintf(stderr,
+          "ws: curl_ws_send returned %d, sent %d\n", result, (int)sent);
+}
+
+static void websocket(CURL *curl)
+{
+  char buffer[256];
+  const struct curl_ws_frame *meta;
+  size_t nread;
+  size_t i = 0;
+  FILE *save = fopen(libtest_arg2, FOPEN_WRITETEXT);
+  if(!save)
+    return;
+
+  /* Three 4097-bytes frames are expected, 12291 bytes */
+  while(true) {
+    CURLcode result =
+      curl_ws_recv(curl, buffer, sizeof(buffer), &nread, &meta);
+    if(result) {
+      if(result == CURLE_AGAIN)
+        /* crude busy-loop */
+        continue;
+      fclose(save);
+      printf("curl_ws_recv returned %d\n", result);
+      return;
+    }
+    printf("%d: nread %zu Age %d Flags %x "
+           "Offset %" CURL_FORMAT_CURL_OFF_T " "
+           "Bytesleft %" CURL_FORMAT_CURL_OFF_T "\n",
+           (int)i,
+           nread, meta->age, meta->flags, meta->offset, meta->bytesleft);
+    i += meta->len;
+    fwrite(buffer, 1, nread, save);
+    /* exit condition */
+    if(!(meta->flags & CURLWS_CONT)) {
+      break;
+    }
+  }
+  fclose(save);
+
+  websocket_close(curl);
+
+  assert(i == 12291);
+}
+
+CURLcode test(char *URL)
+{
+  CURL *curl;
+  CURLcode res = CURLE_OK;
+
+  global_init(CURL_GLOBAL_ALL);
+
+  curl = curl_easy_init();
+  if(curl) {
+    curl_easy_setopt(curl, CURLOPT_URL, URL);
+
+    /* use the callback style */
+    curl_easy_setopt(curl, CURLOPT_USERAGENT, "websocket/2304");
+    libtest_debug_config.nohex = 1;
+    libtest_debug_config.tracetime = 1;
+    curl_easy_setopt(curl, CURLOPT_DEBUGDATA, &libtest_debug_config);
+    curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, libtest_debug_cb);
+    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+    curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 2L); /* websocket style */
+    res = curl_easy_perform(curl);
+    fprintf(stderr, "curl_easy_perform() returned %d\n", res);
+    if(res == CURLE_OK)
+      websocket(curl);
+
+    /* always cleanup */
+    curl_easy_cleanup(curl);
+  }
+  curl_global_cleanup();
+  return res;
+}
+
+#else
+NO_SUPPORT_BUILT_IN
+#endif