CURLINFO_CONN_ID(3) Introduction to Library Functions CURLINFO_CONN_ID(3)

NAME

CURLINFO_CONN_ID - ID of the last connection

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_CONN_ID,
curl_off_t *conn_id);

DESCRIPTION

Pass a pointer to a curl_off_t to receive the connection identifier
last used by the handle. Stores -1 if there was no connection used.

The connection id is unique among all connections using the same
connection cache. This is implicitly the case for all connections in
the same multi handle.

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode result;

curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

/* Perform the request */
result = curl_easy_perform(curl);

if(!result) {
curl_off_t conn_id;
result = curl_easy_getinfo(curl, CURLINFO_CONN_ID, &conn_id);
if(!result) {
printf("Connection used: %" CURL_FORMAT_CURL_OFF_T "\n", conn_id);
}
}
}
}

AVAILABILITY

Added in curl 8.2.0

RETURN VALUE

curl_easy_getinfo(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).

SEE ALSO

CURLINFO_XFER_ID(3), curl_easy_getinfo(3), curl_easy_setopt(3)

libcurl 2026-01-08 CURLINFO_CONN_ID(3)