Tribblix: manual page: CURLOPT_UNIX_SOCKET

CURLOPT_UNIX_SOCKET_PATH(3) Introduction to Library Functions

NAME

CURLOPT_UNIX_SOCKET_PATH - Unix domain socket

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_UNIX_SOCKET_PATH, char *path);

DESCRIPTION

Enables the use of Unix domain sockets as connection endpoint and
sets the path to path. If path is NULL, then Unix domain sockets are
disabled.

When enabled, curl connects to the Unix domain socket instead of
establishing a TCP connection to the host. Since no network
connection is created, curl does not resolve the DNS hostname in the
URL.

The maximum path length on Cygwin, Linux and Solaris is 107. On other
platforms it might be even less.

Proxy and TCP options such as CURLOPT_TCP_NODELAY(3) are not
supported. Proxy options such as CURLOPT_PROXY(3) have no effect
either as these are TCP-oriented, and asking a proxy server to
connect to a certain Unix domain socket is not possible.

The application does not have to keep the string around after setting
this option.

Using this option multiple times makes the last set string override
the previous ones. Set it to NULL to disable its use again.

DEFAULT

NULL - no Unix domain sockets are used.

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_UNIX_SOCKET_PATH, "/tmp/httpd.sock");
curl_easy_setopt(curl, CURLOPT_URL, "http://localhost/");

curl_easy_perform(curl);
}
}

If you are on Linux and somehow have a need for paths larger than 107
bytes, you can use the proc filesystem to bypass the limitation:

int dirfd = open(long_directory_path_to_socket, O_DIRECTORY | O_RDONLY);
char path[108];
snprintf(path, sizeof(path), "/proc/self/fd/%d/httpd.sock", dirfd);
curl_easy_setopt(curl_handle, CURLOPT_UNIX_SOCKET_PATH, path);
/* Be sure to keep dirfd valid until you discard the handle */

AVAILABILITY

Added in curl 7.40.0

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).