CURLOPT_SSH_HOSTKEYFUNCTION(3)                        Library Functions Manual

NAME
       CURLOPT_SSH_HOSTKEYFUNCTION - callback to check host key

SYNOPSIS
       #include <curl/curl.h>

       int keycallback(void *clientp,
                       int keytype,
                       const char *key,
                       size_t keylen);

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_HOSTKEYFUNCTION,
                                 keycallback);

DESCRIPTION
       Pass a pointer to your callback function, which should match the
       prototype shown above. It overrides CURLOPT_SSH_KNOWNHOSTS(3).

       This callback gets called when the verification of the SSH host key is
       needed.

       key is keylen bytes long and is the key to check. keytype says what
       type it is, from the CURLKHTYPE_* series in the curl_khtype enum.

       clientp is a custom pointer set with CURLOPT_SSH_HOSTKEYDATA(3).

       The callback MUST return one of the following return codes to tell
       libcurl how to act:

       CURLKHMATCH_OK
              The host key is accepted, the connection should continue.

       CURLKHMATCH_MISMATCH
              the host key is rejected, the connection is canceled.

DEFAULT
       NULL

PROTOCOLS
       SCP and SFTP

EXAMPLE
       struct mine {
         void *custom;
       };

       int hostkeycb(void *clientp,    /* passed with CURLOPT_SSH_HOSTKEYDATA */
                     int keytype,      /* CURLKHTYPE */
                     const char *key,  /* host key to check */
                     size_t keylen)    /* length of the key */
       {
         /* 'clientp' points to the callback_data struct */
         /* investigate the situation and return the correct value */
         return CURLKHMATCH_OK;
       }
       int main(void)
       {
         struct mine callback_data;
         CURL *curl = curl_easy_init();
         if(curl) {
           curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/thisfile.txt");
           curl_easy_setopt(curl, CURLOPT_SSH_HOSTKEYFUNCTION, hostkeycb);
           curl_easy_setopt(curl, CURLOPT_SSH_HOSTKEYDATA, &callback_data);

           curl_easy_perform(curl);
         }
       }

AVAILABILITY
       Added in 7.84.0 , work only with libssh2 backend.

RETURN VALUE
       Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
       if not.

SEE ALSO
       CURLOPT_SSH_HOSTKEYDATA(3), CURLOPT_SSH_KNOWNHOSTS(3)

libcurl                          April 26 2024  CURLOPT_SSH_HOSTKEYFUNCTION(3)