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

       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)

libcurl                                            2025-03-05                            CURLOPT_PROXY_CAINFO(3)