Ensure XID frame response is encoded as responses

Changes:

    * Modify patty_ax25_sock_send_xid() to require the 'cr' argument,
      which specifies whether the frame address field is to be encoded
      with the 'command' or 'response' bits set as appropriate

include/patty/ax25/sock.h

@@ -130,7 +130,8 @@ ssize_t patty_ax25_sock_send_sabme(patty_ax25_sock *sock, int pf);
 
 ssize_t patty_ax25_sock_send_disc(patty_ax25_sock *sock, int pf);
 
-ssize_t patty_ax25_sock_send_xid(patty_ax25_sock *sock);
+ssize_t patty_ax25_sock_send_xid(patty_ax25_sock *sock,
+                                 enum patty_ax25_frame_cr cr);
 
 ssize_t patty_ax25_sock_write(patty_ax25_sock *sock,
                               void *buf,

src/server.c

@@ -772,7 +772,7 @@ static int server_connect(patty_ax25_server *server,
      * Send an XID frame, to attempt to negotiate AX.25 v2.2 and its default
      * parameters.
      */
-    if (patty_ax25_sock_send_xid(sock) < 0) {
+    if (patty_ax25_sock_send_xid(sock, PATTY_AX25_FRAME_COMMAND) < 0) {
         response.ret = -1;
         response.eno = errno;
 
@@ -1396,7 +1396,7 @@ static int handle_xid(patty_ax25_server *server,
             goto error_sock_save_by_fd;
         }
 
-        return patty_ax25_sock_send_xid(remote);
+        return patty_ax25_sock_send_xid(remote, PATTY_AX25_FRAME_RESPONSE);
     }
 
     return reply_dm(iface, frame, PATTY_AX25_FRAME_FINAL);

src/sock.c

@@ -497,7 +497,8 @@ ssize_t patty_ax25_sock_send_disc(patty_ax25_sock *sock, int pf) {
                                 0);
 }
 
-ssize_t patty_ax25_sock_send_xid(patty_ax25_sock *sock) {
+ssize_t patty_ax25_sock_send_xid(patty_ax25_sock *sock,
+                                 enum patty_ax25_frame_cr cr) {
     patty_ax25_params params;
     char buf[256];
 
@@ -540,7 +541,7 @@ ssize_t patty_ax25_sock_send_xid(patty_ax25_sock *sock) {
     }
 
     return patty_ax25_sock_send(sock,
-                                PATTY_AX25_FRAME_COMMAND,
+                                cr,
                                 control_u(PATTY_AX25_FRAME_XID, 0),
                                 buf,
                                 encoded);