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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 demonstrating how an application can pass in a custom
     24  * socket to libcurl to use. This example also handles the connect itself.
     25  * </DESC>
     26  */
     27 #include <stdio.h>
     28 #include <string.h>
     29 #include <stdlib.h>
     30 #include <curl/curl.h>
     31 
     32 #ifdef WIN32
     33 #include <windows.h>
     34 #include <winsock2.h>
     35 #include <ws2tcpip.h>
     36 #define close closesocket
     37 #else
     38 #include <sys/types.h>        /*  socket types              */
     39 #include <sys/socket.h>       /*  socket definitions        */
     40 #include <netinet/in.h>
     41 #include <arpa/inet.h>        /*  inet (3) funtions         */
     42 #include <unistd.h>           /*  misc. Unix functions      */
     43 #endif
     44 
     45 #include <errno.h>
     46 
     47 /* The IP address and port number to connect to */
     48 #define IPADDR "127.0.0.1"
     49 #define PORTNUM 80
     50 
     51 #ifndef INADDR_NONE
     52 #define INADDR_NONE 0xffffffff
     53 #endif
     54 
     55 static size_t write_data(void *ptr, size_t size, size_t nmemb, void *stream)
     56 {
     57   size_t written = fwrite(ptr, size, nmemb, (FILE *)stream);
     58   return written;
     59 }
     60 
     61 static curl_socket_t opensocket(void *clientp,
     62                                 curlsocktype purpose,
     63                                 struct curl_sockaddr *address)
     64 {
     65   curl_socket_t sockfd;
     66   (void)purpose;
     67   (void)address;
     68   sockfd = *(curl_socket_t *)clientp;
     69   /* the actual externally set socket is passed in via the OPENSOCKETDATA
     70      option */
     71   return sockfd;
     72 }
     73 
     74 static int sockopt_callback(void *clientp, curl_socket_t curlfd,
     75                             curlsocktype purpose)
     76 {
     77   (void)clientp;
     78   (void)curlfd;
     79   (void)purpose;
     80   /* This return code was added in libcurl 7.21.5 */
     81   return CURL_SOCKOPT_ALREADY_CONNECTED;
     82 }
     83 
     84 int main(void)
     85 {
     86   CURL *curl;
     87   CURLcode res;
     88   struct sockaddr_in servaddr;  /*  socket address structure  */
     89   curl_socket_t sockfd;
     90 
     91 #ifdef WIN32
     92   WSADATA wsaData;
     93   int initwsa;
     94 
     95   if((initwsa = WSAStartup(MAKEWORD(2, 0), &wsaData)) != 0) {
     96     printf("WSAStartup failed: %d\n", initwsa);
     97     return 1;
     98   }
     99 #endif
    100 
    101   curl = curl_easy_init();
    102   if(curl) {
    103     /*
    104      * Note that libcurl will internally think that you connect to the host
    105      * and port that you specify in the URL option.
    106      */
    107     curl_easy_setopt(curl, CURLOPT_URL, "http://99.99.99.99:9999");
    108 
    109     /* Create the socket "manually" */
    110     if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == CURL_SOCKET_BAD) {
    111       printf("Error creating listening socket.\n");
    112       return 3;
    113     }
    114 
    115     memset(&servaddr, 0, sizeof(servaddr));
    116     servaddr.sin_family = AF_INET;
    117     servaddr.sin_port   = htons(PORTNUM);
    118 
    119     if(INADDR_NONE == (servaddr.sin_addr.s_addr = inet_addr(IPADDR)))
    120       return 2;
    121 
    122     if(connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) ==
    123        -1) {
    124       close(sockfd);
    125       printf("client error: connect: %s\n", strerror(errno));
    126       return 1;
    127     }
    128 
    129     /* no progress meter please */
    130     curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 1L);
    131 
    132     /* send all data to this function  */
    133     curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
    134 
    135     /* call this function to get a socket */
    136     curl_easy_setopt(curl, CURLOPT_OPENSOCKETFUNCTION, opensocket);
    137     curl_easy_setopt(curl, CURLOPT_OPENSOCKETDATA, &sockfd);
    138 
    139     /* call this function to set options for the socket */
    140     curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
    141 
    142     curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
    143 
    144     res = curl_easy_perform(curl);
    145 
    146     curl_easy_cleanup(curl);
    147 
    148     if(res) {
    149       printf("libcurl error: %d\n", res);
    150       return 4;
    151     }
    152   }
    153   return 0;
    154 }
    155