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.

       (iOS and macOS only) If curl is built  against  Secure  Transport,  then  this  option  is
       supported  for backward compatibility with other SSL engines, but it should not be set. If
       the option is not set, then curl uses the certificates in the system and user Keychain  to
       verify the peer, which is the preferred method of verifying the peer's certificate chain.

       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

       Returns   CURLE_OK   if   the   option  is  supported,  CURLE_UNKNOWN_OPTION  if  not,  or
       CURLE_OUT_OF_MEMORY if there was insufficient heap space.

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)