CURLOPT_PROXY_CAINFO(3)

Usage

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

Overview

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.

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. only

All TLS backends support this option.

Examples

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