CURLOPT_PROXY_CAINFO(3)

NAME
CURLOPT_PROXY_CAINFO - path to proxy Certificate Authority (CA) bundle

SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_CAINFO, char *path);

DESCRIPTION
This option is for connecting to an HTTPS proxy, not an HTTPS server. Pass a char pointer to a null-terminated string naming a file holding one or more certificates to verify the HTTPS proxy with. If CURLOPT_PROXY_SSL_VERIFYPEER(3) is zero and you avoid verifying the server's certificate, CURLOPT_PROXY_CAINFO(3) need not even indicate an accessible file. This option is by default set to the system path where libcurl's CA certificate bundle is assumed to be stored, as established at build time. The application does not have to keep the string around after setting this option. Using this option multiple times makes the last set string override the previous ones. Set it to NULL to disable its use again and switches back to internal default. The default value for this can be figured out with CURLINFO_CAINFO(3).

DEFAULT
Built-in system specific

PROTOCOLS
This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. All TLS backends support this option.

EXAMPLE
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    /* using an HTTPS proxy */
    curl_easy_setopt(curl, CURLOPT_PROXY, "https://localhost:443");
    curl_easy_setopt(curl, CURLOPT_PROXY_CAINFO, "/etc/certs/cabundle.pem");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

NOTES
For TLS backends that do not support certificate files, the CURLOPT_PROXY_CAINFO(3) option is ignored. Refer to https://curl.se/docs/ssl-compared.html

AVAILABILITY
Added in curl 7.52.0

RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error. CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

SEE ALSO
CURLOPT_CAINFO(3), CURLOPT_CAINFO_BLOB(3), CURLOPT_CAPATH(3), CURLOPT_PROXY_CAINFO_BLOB(3), CURLOPT_PROXY_CAPATH(3), CURLOPT_PROXY_SSL_VERIFYHOST(3), CURLOPT_PROXY_SSL_VERIFYPEER(3), CURLOPT_SSL_VERIFYHOST(3), CURLOPT_SSL_VERIFYPEER(3)