websocket-cb: example doing WebSocket download using callback

Very basic

Closes #11260

diff --git a/docs/examples/Makefile.inc b/docs/examples/Makefile.inc
index 7e0d69c90da0f77d8878a61975cd36f187da975c..98e4bf533bd39de3213e64d811a033639070dc86 100644 (file)
--- a/docs/examples/Makefile.inc
+++ b/docs/examples/Makefile.inc
@@ -117,7 +117,8 @@ check_PROGRAMS = \
   smtp-vrfy \
   sslbackend \
   url2file \
-  urlapi
+  urlapi \
+  websocket-cb
 
 # These examples require external dependencies that may not be commonly
 # available on POSIX systems, so don't bother attempting to compile them here.

diff --git a/docs/examples/websocket-cb.c b/docs/examples/websocket-cb.c
new file mode 100644 (file)
index 0000000..f571746
--- /dev/null
+++ b/docs/examples/websocket-cb.c
@@ -0,0 +1,68 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  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
+ *
+ ***************************************************************************/
+/* <DESC>
+ * WebSocket download-only using write callback
+ * </DESC>
+ */
+#include <stdio.h>
+#include <curl/curl.h>
+
+static size_t writecb(char *b, size_t size, size_t nitems, void *p)
+{
+  CURL *easy = p;
+  size_t i;
+  struct curl_ws_frame *frame = curl_ws_meta(easy);
+  fprintf(stderr, "Type: %s\n", frame->flags & CURLWS_BINARY ?
+          "binary" : "text");
+  fprintf(stderr, "Bytes: %u", (unsigned int)(nitems * size));
+  for(i = 0; i < nitems; i++)
+    fprintf(stderr, "%02x ", (unsigned char)b[i]);
+  return nitems;
+}
+
+int main(void)
+{
+  CURL *curl;
+  CURLcode res;
+
+  curl = curl_easy_init();
+  if(curl) {
+    curl_easy_setopt(curl, CURLOPT_URL, "wss://example.com");
+
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writecb);
+    /* pass the easy handle to the callback */
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, curl);
+
+    /* Perform the request, res will get the return code */
+    res = curl_easy_perform(curl);
+    /* Check for errors */
+    if(res != CURLE_OK)
+      fprintf(stderr, "curl_easy_perform() failed: %s\n",
+              curl_easy_strerror(res));
+
+    /* always cleanup */
+    curl_easy_cleanup(curl);
+  }
+  return 0;
+}