CURLOPT_SSH_KEYFUNCTION(3) curl_easy_setopt options CURLOPT_SSH_KEYFUNCTION(3)

NAME
       CURLOPT_SSH_KEYFUNCTION - callback for known host matching logic

SYNOPSIS
       #include <curl/curl.h>

       enum curl_khstat {
         CURLKHSTAT_FINE_ADD_TO_FILE,
         CURLKHSTAT_FINE,
         CURLKHSTAT_REJECT, /* reject the connection, return an error */
         CURLKHSTAT_DEFER,  /* do not accept it, but we can't answer right
                               now so this causes a CURLE_DEFER error but
                               otherwise the connection will be left intact
                               etc */
       };

       enum curl_khmatch {
         CURLKHMATCH_OK,       /* match */
         CURLKHMATCH_MISMATCH, /* host found, key mismatch! */
         CURLKHMATCH_MISSING,  /* no matching host/key found */
       };

       struct curl_khkey {
         const char *key; /* points to a zero-terminated string encoded with
                             base64 if len is zero, otherwise to the "raw"
                             data */
         size_t len;
         enum curl_khtype keytype;
       };

       int ssh_keycallback(CURL *easy,
                           const struct curl_khkey *knownkey,
                           const struct curl_khkey *foundkey,
                           enum curl_khmatch,
                           void *clientp);

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_KEYFUNCTION,
                                 ssh_keycallback);

DESCRIPTION
       Pass a pointer to your callback function, which should match the proto-
       type shown above.

       It gets called when the known_host matching has been done, to allow the
       application  to act and decide for libcurl how to proceed. The callback
       will only be called if CURLOPT_SSH_KNOWNHOSTS(3) is also set.

       This callback function gets passed the CURL handle, the  key  from  the
       known_hosts  file knownkey, the key from the remote site foundkey, info
       from libcurl on the matching status and a custom pointer (set with CUR-
       LOPT_SSH_KEYDATA(3)).  It MUST return one of the following return codes
       to tell libcurl how to act:

       CURLKHSTAT_FINE_ADD_TO_FILE
              The host+key is accepted and  libcurl  will  append  it  to  the
              known_hosts  file  before  continuing  with the connection. This
              will also add the host+key combo to the known_host pool kept  in
              memory if it wasn't already present there. The adding of data to
              the file is done by completely replacing the  file  with  a  new
              copy, so the permissions of the file must allow this.

       CURLKHSTAT_FINE
              The  host+key is accepted libcurl will continue with the connec-
              tion. This will also add the host+key combo  to  the  known_host
              pool kept in memory if it wasn't already present there.

       CURLKHSTAT_REJECT
              The  host+key  is  rejected. libcurl will deny the connection to
              continue and it will be closed.

       CURLKHSTAT_DEFER
              The host+key is rejected, but the SSH connection is asked to  be
              kept  alive.   This  feature could be used when the app wants to
              somehow return back and act on the host+key situation  and  then
              retry without needing the overhead of setting it up from scratch
              again.

DEFAULT
       NULL

PROTOCOLS
       SFTP and SCP

EXAMPLE
       TODO

AVAILABILITY
       Added in 7.19.6

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

SEE ALSO
       CURLOPT_SSH_KEYDATA(3), CURLOPT_SSH_KNOWNHOSTS(3),

libcurl 7.54.0                 February 03, 2016    CURLOPT_SSH_KEYFUNCTION(3)