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 host name in the
URL to which you told Curl to connect.
When the verify value is 1, curl_easy_setopt will return an error
and the option value will not be changed. It was previously (in 7.28.0 and
earlier) a debug option of some sorts, but it is no longer supported due to
frequently leading to programmer mistakes. Future versions will stop returning
an error for 1 and just treat 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 servers certificates claimed identity.
The server could be lying. To control lying, see
CURLOPT_SSL_VERIFYPEER(3). If libcurl is built against NSS and
CURLOPT_SSL_VERIFYPEER(3) is zero, CURLOPT_SSL_VERIFYHOST(3) is
also set to zero and cannot be overridden.
CURL *curl = curl_easy_init();
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);