NAME

       curl_easy_recv - receives raw data on an "easy" connection

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_recv(CURL *curl, void *buffer, size_t buflen, size_t *n);

DESCRIPTION

       This  function  receives raw data from the established connection. You may use it together
       with curl_easy_send(3) to implement custom protocols using libcurl. This functionality can
       be  particularly  useful  if  you use proxies and/or SSL encryption: libcurl takes care of
       proxy negotiation and connection setup.

       buffer is a pointer to your buffer memory that gets populated by the received data. buflen
       is  the  maximum  amount  of  data  you  can  get in that buffer. The variable n points to
       receives the number of received bytes.

       To  establish  the  connection,  set   CURLOPT_CONNECT_ONLY(3)   option   before   calling
       curl_easy_perform(3)  or  curl_multi_perform(3). Note that curl_easy_recv(3) does not work
       on connections that were created without this option.

       The call returns CURLE_AGAIN if there is  no  data  to  read  -  the  socket  is  used  in
       non-blocking  mode  internally.  When  CURLE_AGAIN  is returned, use your operating system
       facilities  like  select(2)  to  wait  for  data.  The  socket  may  be   obtained   using
       curl_easy_getinfo(3) with CURLINFO_ACTIVESOCKET(3).

       Wait  on the socket only if curl_easy_recv(3) returns CURLE_AGAIN.  The reason for this is
       libcurl or the SSL library may internally cache  some  data,  therefore  you  should  call
       curl_easy_recv(3) until all data is read which would include any cached data.

       Furthermore  if  you  wait  on  the  socket  and  it  tells  you  there  is  data to read,
       curl_easy_recv(3) may return CURLE_AGAIN if the only data that was read was  for  internal
       SSL processing, and no other data is available.

PROTOCOLS

       This functionality affects all supported protocols

EXAMPLE

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           CURLcode res;
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
           /* Do not do the transfer - only connect to host */
           curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
           res = curl_easy_perform(curl);

           if(res == CURLE_OK) {
             char buf[256];
             size_t nread;
             long sockfd;

             /* Extract the socket from the curl handle - we need it for waiting. */
             res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);

             /* read data */
             res = curl_easy_recv(curl, buf, sizeof(buf), &nread);
           }
         }
       }

AVAILABILITY

       Added in curl 7.18.2

RETURN VALUE

       On  success,  returns  CURLE_OK,  stores  the received data into buffer, and the number of
       bytes it actually read into *n.

       On failure, returns the appropriate error code.

       The function may return CURLE_AGAIN. In this case, use your operating system facilities to
       wait until data can be read, and retry.

       Reading exactly 0 bytes indicates a closed connection.

       If  there  is no socket available to use from the previous transfer, this function returns
       CURLE_UNSUPPORTED_PROTOCOL.

SEE ALSO

       curl_easy_getinfo(3), curl_easy_perform(3), curl_easy_send(3), curl_easy_setopt(3)