Github user mike-jumper commented on a diff in the pull request:
https://github.com/apache/guacamole-server/pull/164#discussion_r191093916
--- Diff: src/common-ssh/ssh.c ---
@@ -518,6 +520,71 @@ guac_common_ssh_session*
guac_common_ssh_create_session(guac_client* client,
return NULL;
}
+ /* SSH known host key checking. */
+ LIBSSH2_KNOWNHOSTS *ssh_known_hosts = libssh2_knownhost_init(session);
+ int num_known_hosts = 0;
+
+ /* Add host key provided from settings */
+ if (host_key && strcmp(host_key, "") != 0) {
+
+ int kh_add = libssh2_knownhost_readline(ssh_known_hosts, host_key,
strlen(host_key),
+ LIBSSH2_KNOWNHOST_FILE_OPENSSH);
+ num_known_hosts++;
+
+ if (kh_add)
+ guac_client_log(client, GUAC_LOG_WARNING, "Failed to add
provided host key"
+ " to known hosts store for %s. Error was %d",
hostname, kh_add);
+
+ }
+
+ /* Otherwise, we look for a ssh_known_hosts file within GUACAMOLE_HOME
and read that in. */
+ else {
+ const char *known_hosts = "/etc/guacamole/ssh_known_hosts";
+ num_known_hosts = libssh2_knownhost_readfile(ssh_known_hosts,
known_hosts, LIBSSH2_KNOWNHOST_FILE_OPENSSH);
+ }
+
+ /* If we've found a provided set of host keys, check against them. */
+ if (num_known_hosts > 0) {
+ /* Get fingerprint of host we're connecting to */
+ size_t fp_len;
+ int fp_type;
+ const char *fingerprint = libssh2_session_hostkey(session,
&fp_len, &fp_type);
+
+ if (!fingerprint)
+ guac_client_abort(client, GUAC_PROTOCOL_STATUS_SERVER_ERROR,
+ "Failed to get fingerprint for host %s", hostname);
+
+ /* Check fingerprint against known hosts */
+ struct libssh2_knownhost *host;
+ int kh_check = libssh2_knownhost_checkp(ssh_known_hosts, hostname,
atoi(port),
--- End diff --
What happens here if `fingerprint` is `NULL`, as checked earlier?
---
