xref: /aosp_15_r20/external/curl/docs/libcurl/opts/CURLOPT_LOCALPORTRANGE.md (revision 6236dae45794135f37c4eb022389c904c8b0090d)

---
c: Copyright (C) Daniel Stenberg, <[email protected]>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_LOCALPORTRANGE
Section: 3
Source: libcurl
See-also:
  - CURLOPT_INTERFACE (3)
  - CURLOPT_LOCALPORT (3)
Protocol:
  - All
Added-in: 7.15.2
---

# NAME

CURLOPT_LOCALPORTRANGE - number of additional local ports to try

# SYNOPSIS

~~~c
#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%

# EXAMPLE

~~~c
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%

# RETURN VALUE

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