feat: implement proxy jump using libssh

tests: modify proxyjump tests to check for ssh_jump_info_struct

tests: add proxyjump functionality test

feat: add SSH_OPTIONS_PROXYJUMP

tests: proxyjump, check authentication

fix: ssh_socket_connect_proxyjump add exit label to exit on error

feat: implement io forwarding using pthread

feat: proxyjump: use threading instead of forking

feat: proxyjump: cancel forwarding threads on ssh_disconnect

fix: proxyjump remove ProxyJump bool and put pthread ifdefs

feat: use ssh_event for io forwarding instead of threads

reformat: tests to use assert_int_not_equal

fix: link to pthread

refactor: make function to free proxy jump list

docs: add comment for proxy jump channel

feat: add env variable to enable libssh proxy jump

feat: open channel for proxyjump like OpenSSH

feat: add more tests for proxy jump

fix: use a global variable to close io forwarding, this prevents segfaults

fix: handle proxy list in thread without creating copy
Signed-off-by: Gauravsingh Sisodia <xaerru@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Eshan Kelkar <eshankelkar@galorithm.com>

src/client.c

@@ -589,6 +589,13 @@ int ssh_connect(ssh_session session)
         session->session_state = SSH_SESSION_STATE_SOCKET_CONNECTED;
         ssh_socket_set_fd(session->socket, session->opts.fd);
         ret = SSH_OK;
+#ifndef _WIN32
+#ifdef HAVE_PTHREAD
+    } else if (ssh_libssh_proxy_jumps() &&
+               ssh_list_count(session->opts.proxy_jumps) != 0) {
+        ret = ssh_socket_connect_proxyjump(session->socket);
+#endif /* HAVE_PTHREAD */
+#endif /* _WIN32 */
     } else if (session->opts.ProxyCommand != NULL) {
 #ifdef WITH_EXEC
         ret = ssh_socket_connect_proxycommand(session->socket,
@@ -758,6 +765,7 @@ ssh_session_set_disconnect_message(ssh_session session, const char *message)
     return SSH_OK;
 }
 
+extern int proxy_disconnect;
 
 /**
  * @brief Disconnect from a session (client or server).
@@ -780,6 +788,14 @@ ssh_disconnect(ssh_session session)
         return;
     }
 
+#ifndef _WIN32
+    /* Only send the disconnect to all other threads when the root session calls
+     * ssh_disconnect() */
+    if (session->proxy_root) {
+        proxy_disconnect = 1;
+    }
+#endif
+
     if (session->disconnect_message == NULL) {
         session->disconnect_message = strdup("Bye Bye") ;
         if (session->disconnect_message == NULL) {