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Updated: Wednesday, July 27, 2022
 
 

CURLMOPT_SOCKETFUNCTION (3)

Name

CURLMOPT_SOCKETFUNCTION - callback informed about what to wait for

Synopsis

#include <curl/curl.h>

int socket_callback(CURL *easy,      /* easy handle */
curl_socket_t s, /* socket */
int what,        /* describes the socket */
void *userp,     /* private callback pointer */
void *socketp);  /* private socket pointer */

CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_SOCKETFUNCTION, socket_callback);

Description

curl_multi_setopt options                           CURLMOPT_SOCKETFUNCTION(3)



NAME
       CURLMOPT_SOCKETFUNCTION - callback informed about what to wait for

SYNOPSIS
       #include <curl/curl.h>

       int socket_callback(CURL *easy,      /* easy handle */
                           curl_socket_t s, /* socket */
                           int what,        /* describes the socket */
                           void *userp,     /* private callback pointer */
                           void *socketp);  /* private socket pointer */

       CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_SOCKETFUNCTION, socket_callback);

DESCRIPTION
       Pass a pointer to your callback function, which should match the proto-
       type shown above.

       When the curl_multi_socket_action(3) function is called, it informs the
       application  about  updates  in  the socket (file descriptor) status by
       doing none, one, or multiple calls to the socket_callback. The callback
       function  gets  status updates with changes since the previous time the
       callback was called. If the given callback pointer is set to  NULL,  no
       callback will be called.

CALLBACK ARGUMENTS
       easy identifies the specific transfer for which this update is related.

       s is the specific socket this function invocation concerns. If the what
       argument is not CURL_POLL_REMOVE then it holds information  about  what
       activity  on this socket the application is supposed to monitor. Subse-
       quent calls to this callback might update the what bits  for  a  socket
       that is already monitored.

       The  socket  callback  should  return 0 on success, and -1 on error. If
       this callback returns error, all transfers  currently  in  progress  in
       this multi handle will be aborted and fail.

       userp is set with CURLMOPT_SOCKETDATA(3).

       socketp is set with curl_multi_assign(3) or will be NULL.

       The  what  parameter  informs  the  callback on the status of the given
       socket. It can hold one of these values:

       CURL_POLL_IN
              Wait for incoming data. For the socket to become readable.

       CURL_POLL_OUT
              Wait for outgoing data. For the socket to become writable.

       CURL_POLL_INOUT
              Wait for incoming and outgoing data. For the  socket  to  become
              readable or writable.

       CURL_POLL_REMOVE
              The  specified  socket/file  descriptor  is  no  longer  used by
              libcurl.

DEFAULT
       NULL (no callback)

PROTOCOLS
       All

EXAMPLE
       static int sock_cb(CURL *e, curl_socket_t s, int what, void *cbp, void *sockp)
       {
         GlobalInfo *g = (GlobalInfo*) cbp;
         SockInfo *fdp = (SockInfo*) sockp;

         if(what == CURL_POLL_REMOVE) {
           remsock(fdp);
         }
         else {
           if(!fdp) {
             addsock(s, e, what, g);
           }
           else {
             setsock(fdp, s, e, what, g);
           }
         }
         return 0;
       }

       main()
       {
         GlobalInfo setup;
         /* ... use socket callback and custom pointer */
         curl_multi_setopt(multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
         curl_multi_setopt(multi, CURLMOPT_SOCKETDATA, &setup);
       }

AVAILABILITY
       Added in 7.15.4

RETURN VALUE
       Returns CURLM_OK.


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | web/curl         |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+

SEE ALSO
       CURLMOPT_SOCKETDATA(3),  curl_multi_socket_action(3),   CURLMOPT_TIMER-
       FUNCTION(3)



NOTES
       Source  code  for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-
       code-downloads.html.

       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source       was       downloaded      from       https://curl.se/down-
       load/curl-7.83.1.tar.bz2.

       Further information about this software can be found on the open source
       community website at http://curl.haxx.se/.



libcurl 7.83.1                 December 02, 2021
                                                    CURLMOPT_SOCKETFUNCTION(3)