BGP: Shutdown communication (RFC 8203)

The patch implements BGP Administrative Shutdown Communication (RFC 8203)
allowing BGP operators to pass messages related to BGP session
administrative shutdown/restart. It handles both transmit and receive of
shutdown messages. Messages are logged and may be displayed by show
protocol all command.

Thanks to Job Snijders for the basic patch.

1 files changed, 46 insertions, 12 deletions

diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index ab87bdcc..af3b15b5 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -1494,38 +1494,72 @@ bgp_error_dsc(unsigned code, unsigned subcode)
   return buff;
 }
 
+/* RFC 8203 - shutdown communication message */
+static int
+bgp_handle_message(struct bgp_proto *p, byte *data, uint len, byte **bp)
+{
+  byte *msg = data + 1;
+  uint msg_len = data[0];
+  uint i;
+
+  /* Handle zero length message */
+  if (msg_len == 0)
+    return 1;
+
+  /* Handle proper message */
+  if ((msg_len > 128) && (msg_len + 1 > len))
+    return 0;
+
+  /* Some elementary cleanup */
+  for (i = 0; i < msg_len; i++)
+    if (msg[i] < ' ')
+      msg[i] = ' ';
+
+  proto_set_message(&p->p, msg, msg_len);
+  *bp += bsprintf(*bp, ": \"%s\"", p->p.message);
+  return 1;
+}
+
 void
 bgp_log_error(struct bgp_proto *p, u8 class, char *msg, unsigned code, unsigned subcode, byte *data, unsigned len)
 {
-  const byte *name;
-  byte *t, argbuf[36];
+  byte argbuf[256], *t = argbuf;
   unsigned i;
 
   /* Don't report Cease messages generated by myself */
   if (code == 6 && class == BE_BGP_TX)
     return;
 
-  name = bgp_error_dsc(code, subcode);
-  t = argbuf;
+  /* Reset shutdown message */
+  if ((code == 6) && ((subcode == 2) || (subcode == 4)))
+    proto_set_message(&p->p, NULL, 0);
+
   if (len)
     {
-      *t++ = ':';
-      *t++ = ' ';
-
+      /* Bad peer AS - we would like to print the AS */
       if ((code == 2) && (subcode == 2) && ((len == 2) || (len == 4)))
 	{
-	  /* Bad peer AS - we would like to print the AS */
-	  t += bsprintf(t, "%d", (len == 2) ? get_u16(data) : get_u32(data));
+	  t += bsprintf(t, ": %u", (len == 2) ? get_u16(data) : get_u32(data));
 	  goto done;
 	}
+
+      /* RFC 8203 - shutdown communication */
+      if (((code == 6) && ((subcode == 2) || (subcode == 4))))
+	if (bgp_handle_message(p, data, len, &t))
+	  goto done;
+
+      *t++ = ':';
+      *t++ = ' ';
       if (len > 16)
 	len = 16;
       for (i=0; i<len; i++)
 	t += bsprintf(t, "%02x", data[i]);
     }
- done:
+
+done:
   *t = 0;
-  log(L_REMOTE "%s: %s: %s%s", p->p.name, msg, name, argbuf);
+  const byte *dsc = bgp_error_dsc(code, subcode);
+  log(L_REMOTE "%s: %s: %s%s", p->p.name, msg, dsc, argbuf);
 }
 
 static void
@@ -1571,7 +1605,7 @@ bgp_rx_notification(struct bgp_conn *conn, byte *pkt, uint len)
   if (err) 
     {
       bgp_update_startup_delay(p);
-      bgp_stop(p, 0);
+      bgp_stop(p, 0, NULL, 0);
     }
 }