int libssh2_knownhost_check(LIBSSH2_KNOWNHOSTS *hosts,
char *host, char *key, size_t keylen,
struct libssh2_knownhost **knownhost);
host is a pointer the host name in plain text. The host name can be the IP numerical address of the host or the full name.
key is a pointer to the key for the given host.
keylen is the total size in bytes of the key pointed to by the key argument
typemask is a bitmask that specifies format and info about the data passed to this function. Specificly, it details what format the host name is, what format the key is and what key type it is.
The host name is given as one of the following types: LIBSSH2_KNOWNHOST_TYPE_PLAIN or LIBSSH2_KNOWNHOST_TYPE_CUSTOM.
The key is encoded using one of the following encodings: LIBSSH2_KNOWNHOST_KEYENC_RAW or LIBSSH2_KNOWNHOST_KEYENC_BASE64.
knownhost if set to non-NULL, it must be a pointer to a 'struct libssh2_knownhost' pointer that gets filled in to point to info about a known host that matches or partially matches.
LIBSSH2_KNOWNHOST_CHECK_FAILURE - something prevented the check to be made
LIBSSH2_KNOWNHOST_CHECK_NOTFOUND - no host match was found
LIBSSH2_KNOWNHOST_CHECK_MATCH - hosts and keys match.
LIBSSH2_KNOWNHOST_CHECK_MISMATCH - host was found, but the keys didn't match!