curl/docs/libcurl/opts/CURLOPT_CAINFO.3

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.TH CURLOPT_CAINFO 3 "17 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options"
.SH NAME
CURLOPT_CAINFO \- path to Certificate Authority (CA) bundle
.SH SYNOPSIS
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CAINFO, char *path);
.SH DESCRIPTION
Pass a char * to a zero terminated string naming a file holding one or more
certificates to verify the peer with.

If \fICURLOPT_SSL_VERIFYPEER(3)\fP is zero and you avoid verifying the
server's certificate, \fICURLOPT_CAINFO(3)\fP need not even indicate an
accessible file.

This option is by default set to the system path where libcurl's cacert bundle
is assumed to be stored, as established at build time.

If curl is built against the NSS SSL library, the NSS PEM PKCS#11 module
(libnsspem.so) needs to be available for this option to work properly.
Starting with curl-7.55.0, if both \fICURLOPT_CAINFO(3)\fP and
\fICURLOPT_CAPATH(3)\fP are unset, NSS-linked libcurl tries to load
libnssckbi.so, which contains a more comprehensive set of trust information
than supported by nss-pem, because libnssckbi.so also includes information
about distrusted certificates.

(iOS and macOS) 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 will use the
certificates in the system and user Keychain to verify the peer, which is the
preferred method of verifying the peer's certificate chain.

(Schannel) This option is supported for Schannel in Windows 7 or later but we
recommend not using it until Windows 8 since it works better starting then.
Added in libcurl 7.60. This option is supported for backward compatibility
with other SSL engines; instead it is recommended to use Windows' store of
root certificates (the default for Schannel).

The application does not have to keep the string around after setting this
option.
.SH DEFAULT
Built-in system specific
.SH PROTOCOLS
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
  curl_easy_setopt(curl, CURLOPT_CAINFO, "/etc/certs/cabundle.pem");
  ret = curl_easy_perform(curl);
  curl_easy_cleanup(curl);
}
.fi
.SH AVAILABILITY
For SSL engines that don't support certificate files the CURLOPT_CAINFO option
is ignored. Refer to https://curl.haxx.se/docs/ssl-compared.html
.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_CAPATH "(3), "
.BR CURLOPT_SSL_VERIFYPEER "(3), " CURLOPT_SSL_VERIFYHOST "(3), "