**************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
**************************************************************************

CURLINFO_PROXY_ERROR - get the detailed (SOCKS) proxy error

#include <curl/curl.h>

typedef enum {
 CURLPX_OK,
 CURLPX_BAD_ADDRESS_TYPE,
 CURLPX_BAD_VERSION,
 CURLPX_CLOSED,
 CURLPX_GSSAPI,
 CURLPX_GSSAPI_PERMSG,
 CURLPX_GSSAPI_PROTECTION,
 CURLPX_IDENTD,
 CURLPX_IDENTD_DIFFER,
 CURLPX_LONG_HOSTNAME,
 CURLPX_LONG_PASSWD,
 CURLPX_LONG_USER,
 CURLPX_NO_AUTH,
 CURLPX_RECV_ADDRESS,
 CURLPX_RECV_AUTH,
 CURLPX_RECV_CONNECT,
 CURLPX_RECV_REQACK,
 CURLPX_REPLY_ADDRESS_TYPE_NOT_SUPPORTED,
 CURLPX_REPLY_COMMAND_NOT_SUPPORTED,
 CURLPX_REPLY_CONNECTION_REFUSED,
 CURLPX_REPLY_GENERAL_SERVER_FAILURE,
 CURLPX_REPLY_HOST_UNREACHABLE,
 CURLPX_REPLY_NETWORK_UNREACHABLE,
 CURLPX_REPLY_NOT_ALLOWED,
 CURLPX_REPLY_TTL_EXPIRED,
 CURLPX_REPLY_UNASSIGNED,
 CURLPX_REQUEST_FAILED,
 CURLPX_RESOLVE_HOST,
 CURLPX_SEND_AUTH,
 CURLPX_SEND_CONNECT,
 CURLPX_SEND_REQUEST,
 CURLPX_UNKNOWN_FAIL,
 CURLPX_UNKNOWN_MODE,
 CURLPX_USER_REJECTED,
 CURLPX_LAST /* never use */
} CURLproxycode;

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_PROXY_ERROR, long *detail);

Pass a pointer to a long to receive a detailed error code when the most recent transfer returned a CURLE_PROXY error. The return value will match the CURLproxycode set. The returned value will be zero (equal to CURLPX_OK) if no such response code was available. All that can be done over SOCKS

CURL *curl = curl_easy_init();
if(curl) {
 CURLcode res;
 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

 curl_easy_setopt(curl, CURLOPT_PROXY, "socks5://127.0.0.1");
 res = curl_easy_perform(curl);
 if(res == CURLE_PROXY) {
 long proxycode;
 res = curl_easy_getinfo(curl, CURLINFO_PROXY_ERROR, &proxycode);
 if(!res && proxycode)
 printf("The detailed proxy error: %ld\\n", proxycode);
 }
 curl_easy_cleanup(curl);
}

Added in 7.73.0 Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. CURLINFO_RESPONSE_CODE "(3), " libcurl-errors "(3), " curl_easy_getinfo "(3), " curl_easy_setopt "(3), "