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      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 /* <DESC>
     23  * An example of curl_easy_send() and curl_easy_recv() usage.
     24  * </DESC>
     25  */
     26 
     27 #include <stdio.h>
     28 #include <string.h>
     29 #include <curl/curl.h>
     30 
     31 /* Auxiliary function that waits on the socket. */
     32 static int wait_on_socket(curl_socket_t sockfd, int for_recv, long timeout_ms)
     33 {
     34   struct timeval tv;
     35   fd_set infd, outfd, errfd;
     36   int res;
     37 
     38   tv.tv_sec = timeout_ms / 1000;
     39   tv.tv_usec= (timeout_ms % 1000) * 1000;
     40 
     41   FD_ZERO(&infd);
     42   FD_ZERO(&outfd);
     43   FD_ZERO(&errfd);
     44 
     45   FD_SET(sockfd, &errfd); /* always check for error */
     46 
     47   if(for_recv) {
     48     FD_SET(sockfd, &infd);
     49   }
     50   else {
     51     FD_SET(sockfd, &outfd);
     52   }
     53 
     54   /* select() returns the number of signalled sockets or -1 */
     55   res = select(sockfd + 1, &infd, &outfd, &errfd, &tv);
     56   return res;
     57 }
     58 
     59 int main(void)
     60 {
     61   CURL *curl;
     62   CURLcode res;
     63   /* Minimalistic http request */
     64   const char *request = "GET / HTTP/1.0\r\nHost: example.com\r\n\r\n";
     65   curl_socket_t sockfd; /* socket */
     66   long sockextr;
     67   size_t iolen;
     68   curl_off_t nread;
     69 
     70   /* A general note of caution here: if you're using curl_easy_recv() or
     71      curl_easy_send() to implement HTTP or _any_ other protocol libcurl
     72      supports "natively", you're doing it wrong and you should stop.
     73 
     74      This example uses HTTP only to show how to use this API, it does not
     75      suggest that writing an application doing this is sensible.
     76   */
     77 
     78   curl = curl_easy_init();
     79   if(curl) {
     80     curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
     81     /* Do not do the transfer - only connect to host */
     82     curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
     83     res = curl_easy_perform(curl);
     84 
     85     if(CURLE_OK != res) {
     86       printf("Error: %s\n", strerror(res));
     87       return 1;
     88     }
     89 
     90     /* Extract the socket from the curl handle - we'll need it for waiting.
     91      * Note that this API takes a pointer to a 'long' while we use
     92      * curl_socket_t for sockets otherwise.
     93      */
     94     res = curl_easy_getinfo(curl, CURLINFO_LASTSOCKET, &sockextr);
     95 
     96     if(CURLE_OK != res) {
     97       printf("Error: %s\n", curl_easy_strerror(res));
     98       return 1;
     99     }
    100 
    101     sockfd = (curl_socket_t)sockextr;
    102 
    103     /* wait for the socket to become ready for sending */
    104     if(!wait_on_socket(sockfd, 0, 60000L)) {
    105       printf("Error: timeout.\n");
    106       return 1;
    107     }
    108 
    109     puts("Sending request.");
    110     /* Send the request. Real applications should check the iolen
    111      * to see if all the request has been sent */
    112     res = curl_easy_send(curl, request, strlen(request), &iolen);
    113 
    114     if(CURLE_OK != res) {
    115       printf("Error: %s\n", curl_easy_strerror(res));
    116       return 1;
    117     }
    118     puts("Reading response.");
    119 
    120     /* read the response */
    121     for(;;) {
    122       char buf[1024];
    123 
    124       wait_on_socket(sockfd, 1, 60000L);
    125       res = curl_easy_recv(curl, buf, 1024, &iolen);
    126 
    127       if(CURLE_OK != res)
    128         break;
    129 
    130       nread = (curl_off_t)iolen;
    131 
    132       printf("Received %" CURL_FORMAT_CURL_OFF_T " bytes.\n", nread);
    133     }
    134 
    135     /* always cleanup */
    136     curl_easy_cleanup(curl);
    137   }
    138   return 0;
    139 }
    140