SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXYUSERNAME,
char *username);
DESCRIPTION
Pass a char * as parameter, which should be pointing to the zero terminated user name to use for the transfer.CURLOPT_PROXYUSERNAME(3) sets the user name to be used in protocol authentication with the proxy.
To specify the proxy password use the CURLOPT_PROXYPASSWORD(3).