115 lines
3.3 KiB
Markdown
115 lines
3.3 KiB
Markdown
|
---
|
||
|
|
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
|
||
|
|
SPDX-License-Identifier: curl
|
||
|
|
Title: CURLOPT_SSL_VERIFYHOST
|
||
|
|
Section: 3
|
||
|
|
Source: libcurl
|
||
|
|
See-also:
|
||
|
|
- CURLOPT_CAINFO (3)
|
||
|
|
- CURLOPT_PINNEDPUBLICKEY (3)
|
||
|
|
- CURLOPT_SSL_VERIFYPEER (3)
|
||
|
|
---
|
||
|
|
|
||
|
|
# NAME
|
||
|
|
|
||
|
|
CURLOPT_SSL_VERIFYHOST - verify the certificate's name against host
|
||
|
|
|
||
|
|
# SYNOPSIS
|
||
|
|
|
||
|
|
~~~c
|
||
|
|
#include <curl/curl.h>
|
||
|
|
|
||
|
|
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_VERIFYHOST, long verify);
|
||
|
|
~~~
|
||
|
|
|
||
|
|
# DESCRIPTION
|
||
|
|
|
||
|
|
Pass a long as parameter specifying what to *verify*.
|
||
|
|
|
||
|
|
This option determines whether libcurl verifies that the server cert is for
|
||
|
|
the server it is known as.
|
||
|
|
|
||
|
|
When negotiating TLS and SSL connections, the server sends a certificate
|
||
|
|
indicating its identity.
|
||
|
|
|
||
|
|
When CURLOPT_SSL_VERIFYHOST(3) is 2, that certificate must indicate that
|
||
|
|
the server is the server to which you meant to connect, or the connection
|
||
|
|
fails. Simply put, it means it has to have the same name in the certificate as
|
||
|
|
is in the URL you operate against.
|
||
|
|
|
||
|
|
Curl considers the server the intended one when the Common Name field or a
|
||
|
|
Subject Alternate Name field in the certificate matches the hostname in the
|
||
|
|
URL to which you told Curl to connect.
|
||
|
|
|
||
|
|
If *verify* value is set to 1:
|
||
|
|
|
||
|
|
In 7.28.0 and earlier: treated as a debug option of some sorts, not supported
|
||
|
|
anymore due to frequently leading to programmer mistakes.
|
||
|
|
|
||
|
|
From 7.28.1 to 7.65.3: setting it to 1 made curl_easy_setopt(3) return
|
||
|
|
an error and leaving the flag untouched.
|
||
|
|
|
||
|
|
From 7.66.0: treats 1 and 2 the same.
|
||
|
|
|
||
|
|
When the *verify* value is 0, the connection succeeds regardless of the
|
||
|
|
names in the certificate. Use that ability with caution!
|
||
|
|
|
||
|
|
The default value for this option is 2.
|
||
|
|
|
||
|
|
This option controls checking the server's certificate's claimed identity.
|
||
|
|
The server could be lying. To control lying, see CURLOPT_SSL_VERIFYPEER(3).
|
||
|
|
|
||
|
|
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.
|
||
|
|
|
||
|
|
When libcurl uses secure protocols it trusts responses and allows for example
|
||
|
|
HSTS and Alt-Svc information to be stored and used subsequently. Disabling
|
||
|
|
certificate verification can make libcurl trust and use such information from
|
||
|
|
malicious servers.
|
||
|
|
|
||
|
|
# LIMITATIONS
|
||
|
|
|
||
|
|
Secure Transport: If *verify* value is 0, then SNI is also disabled. SNI is
|
||
|
|
a TLS extension that sends the hostname to the server. The server may use that
|
||
|
|
information to do such things as sending back a specific certificate for the
|
||
|
|
hostname, or forwarding the request to a specific origin server. Some hostnames
|
||
|
|
may be inaccessible if SNI is not sent.
|
||
|
|
|
||
|
|
# DEFAULT
|
||
|
|
|
||
|
|
2
|
||
|
|
|
||
|
|
# PROTOCOLS
|
||
|
|
|
||
|
|
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
|
||
|
|
|
||
|
|
# EXAMPLE
|
||
|
|
|
||
|
|
~~~c
|
||
|
|
int main(void)
|
||
|
|
{
|
||
|
|
CURL *curl = curl_easy_init();
|
||
|
|
if(curl) {
|
||
|
|
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
|
||
|
|
|
||
|
|
/* Set the default value: strict name check please */
|
||
|
|
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 2L);
|
||
|
|
|
||
|
|
curl_easy_perform(curl);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
~~~
|
||
|
|
|
||
|
|
# AVAILABILITY
|
||
|
|
|
||
|
|
If built TLS enabled.
|
||
|
|
|
||
|
|
# RETURN VALUE
|
||
|
|
|
||
|
|
Returns CURLE_OK if TLS is supported, and CURLE_UNKNOWN_OPTION if not.
|
||
|
|
|
||
|
|
If 1 is set as argument, *CURLE_BAD_FUNCTION_ARGUMENT* is returned.
|