curl/docs/libcurl/opts/CURLOPT_OPENSOCKETDATA.md
Daniel Stenberg eefcc1bda4
docs: introduce "curldown" for libcurl man page format
curldown is this new file format for libcurl man pages. It is markdown
inspired with differences:

- Each file has a set of leading headers with meta-data
- Supports a small subset of markdown
- Uses .md file extensions for editors/IDE/GitHub to treat them nicely
- Generates man pages very similar to the previous ones
- Generates man pages that still convert nicely to HTML on the website
- Detects and highlights mentions of curl symbols automatically (when
  their man page section is specified)

tools:

- cd2nroff: converts from curldown to nroff man page
- nroff2cd: convert an (old) nroff man page to curldown
- cdall: convert many nroff pages to curldown versions
- cd2cd: verifies and updates a curldown to latest curldown

This setup generates .3 versions of all the curldown versions at build time.

CI:

Since the documentation is now technically markdown in the eyes of many
things, the CI runs many more tests and checks on this documentation,
including proselint, link checkers and tests that make sure we capitalize the
first letter after a period...

Closes #12730
2024-01-23 00:29:02 +01:00

2.1 KiB

c SPDX-License-Identifier Title Section Source See-also
Copyright (C) Daniel Stenberg, <daniel.se>, et al. curl CURLOPT_OPENSOCKETDATA 3 libcurl
CURLOPT_CLOSESOCKETFUNCTION (3)
CURLOPT_OPENSOCKETFUNCTION (3)
CURLOPT_SOCKOPTFUNCTION (3)

NAME

CURLOPT_OPENSOCKETDATA - pointer passed to open socket callback

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_OPENSOCKETDATA, void *pointer);

DESCRIPTION

Pass a pointer that is untouched by libcurl and passed as the first argument in the open socket callback set with CURLOPT_OPENSOCKETFUNCTION(3).

DEFAULT

The default value of this parameter is NULL.

PROTOCOLS

All

EXAMPLE

/* make libcurl use the already established socket 'sockfd' */

static curl_socket_t opensocket(void *clientp,
                                curlsocktype purpose,
                                struct curl_sockaddr *address)
{
  curl_socket_t sockfd;
  sockfd = *(curl_socket_t *)clientp;
  /* the actual externally set socket is passed in via the OPENSOCKETDATA
     option */
  return sockfd;
}

static int sockopt_callback(void *clientp, curl_socket_t curlfd,
                            curlsocktype purpose)
{
  /* This return code was added in libcurl 7.21.5 */
  return CURL_SOCKOPT_ALREADY_CONNECTED;
}

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    extern int sockfd; /* the already connected one */

    /* libcurl thinks that you connect to the host
     * and port that you specify in the URL option. */
    curl_easy_setopt(curl, CURLOPT_URL, "http://99.99.99.99:9999");
    /* call this function to get a socket */
    curl_easy_setopt(curl, CURLOPT_OPENSOCKETFUNCTION, opensocket);
    curl_easy_setopt(curl, CURLOPT_OPENSOCKETDATA, &sockfd);

    /* call this function to set options for the socket */
    curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);

    res = curl_easy_perform(curl);

    curl_easy_cleanup(curl);
  }
}

AVAILABILITY

Added in 7.17.1

RETURN VALUE

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.