examples/http2-pushinmemory: receive HTTP/2 pushed files in memory

Closes #3004

docs/examples/Makefile.inc

@@ -34,7 +34,7 @@ check_PROGRAMS = 10-at-a-time anyauthput cookie_interface debug fileupload \
   imap-tls imap-multi url2file sftpget ftpsget postinmemory http2-download \
   http2-upload http2-serverpush getredirect ftpuploadfrommem               \
   ftpuploadresume sslbackend postit2-formadd multi-formadd                 \
-  shared-connection-cache sftpuploadresume
+  shared-connection-cache sftpuploadresume http2-pushinmemory
 
 # These examples require external dependencies that may not be commonly
 # available on POSIX systems, so don't bother attempting to compile them here.

docs/examples/http2-pushinmemory.c

@@ -0,0 +1,188 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2018, 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.haxx.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.
+ *
+ ***************************************************************************/
+/* <DESC>
+ * HTTP/2 server push. Receive all data in memory.
+ * </DESC>
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* somewhat unix-specific */
+#include <sys/time.h>
+#include <unistd.h>
+
+/* curl stuff */
+#include <curl/curl.h>
+
+struct Memory {
+  char *memory;
+  size_t size;
+};
+
+static size_t
+write_cb(void *contents, size_t size, size_t nmemb, void *userp)
+{
+  size_t realsize = size * nmemb;
+  struct Memory *mem = (struct Memory *)userp;
+  char *ptr = realloc(mem->memory, mem->size + realsize + 1);
+  if(!ptr) {
+    /* out of memory! */
+    printf("not enough memory (realloc returned NULL)\n");
+    return 0;
+  }
+
+  mem->memory = ptr;
+  memcpy(&(mem->memory[mem->size]), contents, realsize);
+  mem->size += realsize;
+  mem->memory[mem->size] = 0;
+
+  return realsize;
+}
+
+#define MAX_FILES 10
+static struct Memory files[MAX_FILES];
+static int pushindex = 1;
+
+static void init_memory(struct Memory *chunk)
+{
+  chunk->memory = malloc(1);  /* grown as needed with realloc */
+  chunk->size = 0;            /* no data at this point */
+}
+
+static void setup(CURL *hnd)
+{
+  /* set the same URL */
+  curl_easy_setopt(hnd, CURLOPT_URL, "https://localhost:8443/index.html");
+
+  /* HTTP/2 please */
+  curl_easy_setopt(hnd, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_0);
+
+  /* we use a self-signed test server, skip verification during debugging */
+  curl_easy_setopt(hnd, CURLOPT_SSL_VERIFYPEER, 0L);
+  curl_easy_setopt(hnd, CURLOPT_SSL_VERIFYHOST, 0L);
+
+  /* write data to a struct  */
+  curl_easy_setopt(hnd, CURLOPT_WRITEFUNCTION, write_cb);
+  init_memory(&files[0]);
+  curl_easy_setopt(hnd, CURLOPT_WRITEDATA, &files[0]);
+
+  /* wait for pipe connection to confirm */
+  curl_easy_setopt(hnd, CURLOPT_PIPEWAIT, 1L);
+}
+
+/* called when there's an incoming push */
+static int server_push_callback(CURL *parent,
+                                CURL *easy,
+                                size_t num_headers,
+                                struct curl_pushheaders *headers,
+                                void *userp)
+{
+  char *headp;
+  int *transfers = (int *)userp;
+  (void)parent; /* we have no use for this */
+  (void)num_headers; /* unused */
+
+  if(pushindex == MAX_FILES)
+    /* can't fit anymore */
+    return CURL_PUSH_DENY;
+
+  /* write to this buffer */
+  init_memory(&files[pushindex]);
+  curl_easy_setopt(easy, CURLOPT_WRITEDATA, &files[pushindex]);
+  pushindex++;
+
+  headp = curl_pushheader_byname(headers, ":path");
+  if(headp)
+    fprintf(stderr, "* Pushed :path '%s'\n", headp /* skip :path + colon */);
+
+  (*transfers)++; /* one more */
+  return CURL_PUSH_OK;
+}
+
+
+/*
+ * Download a file over HTTP/2, take care of server push.
+ */
+int main(void)
+{
+  CURL *easy;
+  CURLM *multi;
+  int still_running; /* keep number of running handles */
+  int transfers = 1; /* we start with one */
+  int i;
+  struct CURLMsg *m;
+
+  /* init a multi stack */
+  multi = curl_multi_init();
+
+  easy = curl_easy_init();
+
+  /* set options */
+  setup(easy);
+
+  /* add the easy transfer */
+  curl_multi_add_handle(multi, easy);
+
+  curl_multi_setopt(multi, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
+  curl_multi_setopt(multi, CURLMOPT_PUSHFUNCTION, server_push_callback);
+  curl_multi_setopt(multi, CURLMOPT_PUSHDATA, &transfers);
+
+  while(transfers) {
+    int rc;
+    CURLMcode mcode = curl_multi_perform(multi, &still_running);
+    if(mcode)
+      break;
+
+    mcode = curl_multi_wait(multi, NULL, 0, 1000, &rc);
+    if(mcode)
+      break;
+
+
+    /*
+     * When doing server push, libcurl itself created and added one or more
+     * easy handles but *we* need to clean them up when they are done.
+     */
+    do {
+      int msgq = 0;;
+      m = curl_multi_info_read(multi, &msgq);
+      if(m && (m->msg == CURLMSG_DONE)) {
+        CURL *e = m->easy_handle;
+        transfers--;
+        curl_multi_remove_handle(multi, e);
+        curl_easy_cleanup(e);
+      }
+    } while(m);
+
+  }
+
+
+  curl_multi_cleanup(multi);
+
+  /* 'pushindex' is now the number of received transfers */
+  for(i = 0; i < pushindex; i++) {
+    /* do something fun with the data, and then free it when done */
+    free(files[i].memory);
+  }
+
+  return 0;
+}