CURLOPT_LOCALPORTRANGE - Man Page

number of additional local ports to try

Synopsis

#include <curl/curl.h>

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

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

Protocols

This functionality affects all supported protocols

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);
  }
}