CURLOPT_PROXYAUTH - Man Page

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXYAUTH, long bitmask);

Pass a long as parameter, which is set to a bitmask, to tell libcurl which HTTP authentication method(s) you want it to use for your proxy authentication. If more than one bit is set, libcurl first queries the site to see what authentication methods it supports and then it picks the best one you allow it to use. For some methods, this induces an extra network round-trip. Set the actual name and password with the CURLOPT_PROXYUSERPWD(3) option.

The bitmask can be constructed by the bits listed and described in the CURLOPT_HTTPAUTH(3) man page.

CURLAUTH_BASIC

This functionality affects all supported protocols

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode ret;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    /* use this proxy */
    curl_easy_setopt(curl, CURLOPT_PROXY, "http://local.example.com:1080");
    /* allow whatever auth the proxy speaks */
    curl_easy_setopt(curl, CURLOPT_PROXYAUTH, CURLAUTH_ANY);
    /* set the proxy credentials */
    curl_easy_setopt(curl, CURLOPT_PROXYUSERPWD, "james:007");
    ret = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Added in curl 7.10.7

Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or CURLE_NOT_BUILT_IN if the bitmask specified no supported authentication methods.

CURLOPT_HTTPAUTH(3), CURLOPT_PROXY(3), CURLOPT_PROXYPORT(3), CURLOPT_PROXYTYPE(3), CURLOPT_PROXYUSERPWD(3)

curl_easy_setopt(3), CURLINFO_PROXYAUTH_AVAIL(3), CURLOPT_AWS_SIGV4(3), CURLOPT_GSSAPI_DELEGATION(3), CURLOPT_HTTPAUTH(3), CURLOPT_NOPROXY(3), CURLOPT_PASSWORD(3), CURLOPT_PROXYPASSWORD(3), CURLOPT_PROXYUSERNAME(3), CURLOPT_PROXYUSERPWD(3), CURLOPT_USERNAME(3), libcurl-symbols(3), libcurl-tutorial(3).