.\" generated by cd2nroff 0.1 from CURLOPT_PROXY_ISSUERCERT.md
.TH CURLOPT_PROXY_ISSUERCERT 3 "March 22 2024" libcurl
.SH NAME
CURLOPT_PROXY_ISSUERCERT \- proxy issuer SSL certificate filename
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_ISSUERCERT, char *file);
.fi
.SH DESCRIPTION
Pass a char pointer to a null\-terminated string naming a \fIfile\fP holding a CA
certificate in PEM format. If the option is set, an additional check against
the peer certificate is performed to verify the issuer of the HTTPS proxy is
indeed the one associated with the certificate provided by the option. This
additional check is useful in multi\-level PKI where one needs to enforce that
the peer certificate is from a specific branch of the tree.

This option makes sense only when used in combination with the
\fICURLOPT_PROXY_SSL_VERIFYPEER(3)\fP option. Otherwise, the result of the
check is not considered as failure.

A specific error code (CURLE_SSL_ISSUER_ERROR) is defined with the option,
which is returned if the setup of the SSL/TLS session has failed due to a
mismatch with the issuer of peer certificate
(\fICURLOPT_PROXY_SSL_VERIFYPEER(3)\fP has to be set too for the check to
fail).

The application does not have to keep the string around after setting this
option.
.SH DEFAULT
NULL
.SH PROTOCOLS
All TLS\-based protocols
.SH EXAMPLE
.nf
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_ISSUERCERT, "/etc/certs/cacert.pem");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
.fi
.SH AVAILABILITY
Added in 7.71.0. This option is supported by the OpenSSL backends.
.SH 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.
.SH SEE ALSO
.BR CURLOPT_ISSUERCERT (3),
.BR CURLOPT_PROXY_SSL_VERIFYHOST (3),
.BR CURLOPT_PROXY_SSL_VERIFYPEER (3),
.BR CURLOPT_SSL_VERIFYHOST (3),
.BR CURLOPT_SSL_VERIFYPEER (3)