curl-w32/docs/libcurl/opts/CURLOPT_LOCALPORTRANGE.md

c	SPDX-License-Identifier	Title	Section	Source	See-also
Copyright (C) Daniel Stenberg, <daniel.se>, et al.	curl	CURLOPT_LOCALPORTRANGE	3	libcurl	CURLOPT_INTERFACE (3) CURLOPT_LOCALPORT (3)

NAME

CURLOPT_LOCALPORTRANGE - number of additional local ports to try

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_LOCALPORTRANGE,
                          long range);

DESCRIPTION

Pass a long. The range argument is the number of attempts libcurl makes to find a working local port number. It starts with the given CURLOPT_LOCALPORT(3) and adds one to the number for each retry. Setting this option to 1 or below makes libcurl only do one try for the exact port number. Port numbers by nature are scarce resources that are busy at times so setting this value to something too low might cause unnecessary connection setup failures.

DEFAULT

1

PROTOCOLS

All

EXAMPLE

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
    curl_easy_setopt(curl, CURLOPT_LOCALPORT, 49152L);
    /* and try 20 more ports following that */
    curl_easy_setopt(curl, CURLOPT_LOCALPORTRANGE, 20L);
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

AVAILABILITY

Added in 7.15.2

RETURN VALUE

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