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.TH CURLOPT_DOH_SSL_VERIFYPEER 3 "11 Feb 2021" libcurl libcurl
.SH NAME
CURLOPT_DOH_SSL_VERIFYPEER \- verify the DoH SSL certificate
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DOH_SSL_VERIFYPEER,
                          long verify);
.fi
.SH DESCRIPTION
Pass a long as parameter set to 1L to enable or 0L to disable.

This option tells curl to verify the authenticity of the DoH (DNS-over-HTTPS)
server's certificate. A value of 1 means curl verifies; 0 (zero) means it
does not.

This option is the DoH equivalent of \fICURLOPT_SSL_VERIFYPEER(3)\fP and
only affects requests to the DoH server.

When negotiating a TLS or SSL connection, the server sends a certificate
indicating its identity. Curl verifies whether the certificate is authentic,
i.e. that you can trust that the server is who the certificate says it is.
This trust is based on a chain of digital signatures, rooted in certification
authority (CA) certificates you supply.  curl uses a default bundle of CA
certificates (the path for that is determined at build time) and you can
specify alternate certificates with the \fICURLOPT_CAINFO(3)\fP option
or the \fICURLOPT_CAPATH(3)\fP option.

When \fICURLOPT_DOH_SSL_VERIFYPEER(3)\fP is enabled, and the verification
fails to prove that the certificate is authentic, the connection fails.  When
the option is zero, the peer certificate verification succeeds regardless.

Authenticating the certificate is not enough to be sure about the server. You
typically also want to ensure that the server is the server you mean to be
talking to.  Use \fICURLOPT_DOH_SSL_VERIFYHOST(3)\fP for that. The check
that the host name in the certificate is valid for the host name you are
connecting to is done independently of the
\fICURLOPT_DOH_SSL_VERIFYPEER(3)\fP option.

WARNING: disabling verification of the certificate allows bad guys to
man-in-the-middle the communication without you knowing it. Disabling
verification makes the communication insecure. Just having encryption on a
transfer is not enough as you cannot be sure that you are communicating with
the correct end-point.
.SH DEFAULT
1
.SH PROTOCOLS
DoH
.SH EXAMPLE
.nf
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

    curl_easy_setopt(curl, CURLOPT_DOH_URL,
                     "https://cloudflare-dns.com/dns-query");

    /* Disable certificate verification of the DoH server */
    curl_easy_setopt(curl, CURLOPT_DOH_SSL_VERIFYPEER, 0L);

    curl_easy_perform(curl);
  }
}
.fi
.SH AVAILABILITY
Added in 7.76.0

If built TLS enabled.
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
.SH "SEE ALSO"
.BR CURLOPT_CAINFO (3),
.BR CURLOPT_CAPATH (3),
.BR CURLOPT_DOH_SSL_VERIFYHOST (3),
.BR CURLOPT_PROXY_SSL_VERIFYHOST (3),
.BR CURLOPT_PROXY_SSL_VERIFYPEER (3),
.BR CURLOPT_SSL_VERIFYHOST (3),
.BR CURLOPT_SSL_VERIFYPEER (3)