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      7  *
      8  * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel (at) haxx.se>, et al.
      9  *
     10  * This software is licensed as described in the file COPYING, which
     11  * you should have received as part of this distribution. The terms
     12  * are also available at https://curl.haxx.se/docs/copyright.html.
     13  *
     14  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
     15  * copies of the Software, and permit persons to whom the Software is
     16  * furnished to do so, under the terms of the COPYING file.
     17  *
     18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
     19  * KIND, either express or implied.
     20  *
     21  ***************************************************************************/
     22 
     23 /* <DESC>
     24  * multi_socket API using libuv
     25  * </DESC>
     26  */
     27 /* Example application using the multi socket interface to download multiple
     28    files in parallel, powered by libuv.
     29 
     30    Requires libuv and (of course) libcurl.
     31 
     32    See https://nikhilm.github.com/uvbook/ for more information on libuv.
     33 */
     34 
     35 #include <stdio.h>
     36 #include <stdlib.h>
     37 #include <uv.h>
     38 #include <curl/curl.h>
     39 
     40 uv_loop_t *loop;
     41 CURLM *curl_handle;
     42 uv_timer_t timeout;
     43 
     44 typedef struct curl_context_s {
     45   uv_poll_t poll_handle;
     46   curl_socket_t sockfd;
     47 } curl_context_t;
     48 
     49 static curl_context_t* create_curl_context(curl_socket_t sockfd)
     50 {
     51   curl_context_t *context;
     52 
     53   context = (curl_context_t *) malloc(sizeof *context);
     54 
     55   context->sockfd = sockfd;
     56 
     57   uv_poll_init_socket(loop, &context->poll_handle, sockfd);
     58   context->poll_handle.data = context;
     59 
     60   return context;
     61 }
     62 
     63 static void curl_close_cb(uv_handle_t *handle)
     64 {
     65   curl_context_t *context = (curl_context_t *) handle->data;
     66   free(context);
     67 }
     68 
     69 static void destroy_curl_context(curl_context_t *context)
     70 {
     71   uv_close((uv_handle_t *) &context->poll_handle, curl_close_cb);
     72 }
     73 
     74 static void add_download(const char *url, int num)
     75 {
     76   char filename[50];
     77   FILE *file;
     78   CURL *handle;
     79 
     80   snprintf(filename, 50, "%d.download", num);
     81 
     82   file = fopen(filename, "wb");
     83   if(!file) {
     84     fprintf(stderr, "Error opening %s\n", filename);
     85     return;
     86   }
     87 
     88   handle = curl_easy_init();
     89   curl_easy_setopt(handle, CURLOPT_WRITEDATA, file);
     90   curl_easy_setopt(handle, CURLOPT_PRIVATE, file);
     91   curl_easy_setopt(handle, CURLOPT_URL, url);
     92   curl_multi_add_handle(curl_handle, handle);
     93   fprintf(stderr, "Added download %s -> %s\n", url, filename);
     94 }
     95 
     96 static void check_multi_info(void)
     97 {
     98   char *done_url;
     99   CURLMsg *message;
    100   int pending;
    101   CURL *easy_handle;
    102   FILE *file;
    103 
    104   while((message = curl_multi_info_read(curl_handle, &pending))) {
    105     switch(message->msg) {
    106     case CURLMSG_DONE:
    107       /* Do not use message data after calling curl_multi_remove_handle() and
    108          curl_easy_cleanup(). As per curl_multi_info_read() docs:
    109          "WARNING: The data the returned pointer points to will not survive
    110          calling curl_multi_cleanup, curl_multi_remove_handle or
    111          curl_easy_cleanup." */
    112       easy_handle = message->easy_handle;
    113 
    114       curl_easy_getinfo(easy_handle, CURLINFO_EFFECTIVE_URL, &done_url);
    115       curl_easy_getinfo(easy_handle, CURLINFO_PRIVATE, &file);
    116       printf("%s DONE\n", done_url);
    117 
    118       curl_multi_remove_handle(curl_handle, easy_handle);
    119       curl_easy_cleanup(easy_handle);
    120       if(file) {
    121         fclose(file);
    122       }
    123       break;
    124 
    125     default:
    126       fprintf(stderr, "CURLMSG default\n");
    127       break;
    128     }
    129   }
    130 }
    131 
    132 static void curl_perform(uv_poll_t *req, int status, int events)
    133 {
    134   int running_handles;
    135   int flags = 0;
    136   curl_context_t *context;
    137 
    138   if(events & UV_READABLE)
    139     flags |= CURL_CSELECT_IN;
    140   if(events & UV_WRITABLE)
    141     flags |= CURL_CSELECT_OUT;
    142 
    143   context = (curl_context_t *) req->data;
    144 
    145   curl_multi_socket_action(curl_handle, context->sockfd, flags,
    146                            &running_handles);
    147 
    148   check_multi_info();
    149 }
    150 
    151 static void on_timeout(uv_timer_t *req)
    152 {
    153   int running_handles;
    154   curl_multi_socket_action(curl_handle, CURL_SOCKET_TIMEOUT, 0,
    155                            &running_handles);
    156   check_multi_info();
    157 }
    158 
    159 static int start_timeout(CURLM *multi, long timeout_ms, void *userp)
    160 {
    161   if(timeout_ms < 0) {
    162     uv_timer_stop(&timeout);
    163   }
    164   else {
    165     if(timeout_ms == 0)
    166       timeout_ms = 1; /* 0 means directly call socket_action, but we'll do it
    167                          in a bit */
    168     uv_timer_start(&timeout, on_timeout, timeout_ms, 0);
    169   }
    170   return 0;
    171 }
    172 
    173 static int handle_socket(CURL *easy, curl_socket_t s, int action, void *userp,
    174                   void *socketp)
    175 {
    176   curl_context_t *curl_context;
    177   int events = 0;
    178 
    179   switch(action) {
    180   case CURL_POLL_IN:
    181   case CURL_POLL_OUT:
    182   case CURL_POLL_INOUT:
    183     curl_context = socketp ?
    184       (curl_context_t *) socketp : create_curl_context(s);
    185 
    186     curl_multi_assign(curl_handle, s, (void *) curl_context);
    187 
    188     if(action != CURL_POLL_IN)
    189       events |= UV_WRITABLE;
    190     if(action != CURL_POLL_OUT)
    191       events |= UV_READABLE;
    192 
    193     uv_poll_start(&curl_context->poll_handle, events, curl_perform);
    194     break;
    195   case CURL_POLL_REMOVE:
    196     if(socketp) {
    197       uv_poll_stop(&((curl_context_t*)socketp)->poll_handle);
    198       destroy_curl_context((curl_context_t*) socketp);
    199       curl_multi_assign(curl_handle, s, NULL);
    200     }
    201     break;
    202   default:
    203     abort();
    204   }
    205 
    206   return 0;
    207 }
    208 
    209 int main(int argc, char **argv)
    210 {
    211   loop = uv_default_loop();
    212 
    213   if(argc <= 1)
    214     return 0;
    215 
    216   if(curl_global_init(CURL_GLOBAL_ALL)) {
    217     fprintf(stderr, "Could not init curl\n");
    218     return 1;
    219   }
    220 
    221   uv_timer_init(loop, &timeout);
    222 
    223   curl_handle = curl_multi_init();
    224   curl_multi_setopt(curl_handle, CURLMOPT_SOCKETFUNCTION, handle_socket);
    225   curl_multi_setopt(curl_handle, CURLMOPT_TIMERFUNCTION, start_timeout);
    226 
    227   while(argc-- > 1) {
    228     add_download(argv[argc], argc);
    229   }
    230 
    231   uv_run(loop, UV_RUN_DEFAULT);
    232   curl_multi_cleanup(curl_handle);
    233 
    234   return 0;
    235 }
    236