Better handle IPv6 routes advertisement (non-)support.

Don't try to enable multiprotocol BGP when the peer says it can't.

Signed-off-by: Benjamin Cama <benoar@dolka.fr>

diff --git a/bgp.c b/bgp.c
index d9c5818..7de3d3f 100644 (file)
--- a/bgp.c
+++ b/bgp.c
@@ -295,6 +295,8 @@ int bgp_start(struct bgp_peer *peer, char *name, int as, int keepalive,
                BGP_PATH_ATTR_MP_UNREACH_NLRI_PARTIAL_SIZE);
     }
 
+    peer->mp_handling = HandlingUnknown;
+
     LOG(4, 0, 0, "Initiating BGP connection to %s (routing %s)\n",
        name, enable ? "enabled" : "suspended");
 
@@ -967,8 +969,6 @@ static int bgp_connect(struct bgp_peer *peer)
 
     LOG(4, 0, 0, "BGP peer %s: state Active\n", inet_ntoa(addr.sin_addr));
 
-    peer->handle_ipv6_routes = 0;
-
     return bgp_send_open(peer);
 }
 
@@ -992,8 +992,6 @@ static int bgp_handle_connect(struct bgp_peer *peer)
 
     LOG(4, 0, 0, "BGP peer %s: state Active\n", peer->name);
 
-    peer->handle_ipv6_routes = 0;
-
     return bgp_send_open(peer);
 }
 
@@ -1260,7 +1258,7 @@ static int bgp_handle_input(struct bgp_peer *peer)
                        continue;
                    }
 
-                   peer->handle_ipv6_routes = 1;
+                   peer->mp_handling = HandleIPv6Routes;
                }
            }
 
@@ -1298,6 +1296,15 @@ static int bgp_handle_input(struct bgp_peer *peer)
                return 0;
            }
 
+           if (notification->error_code == BGP_ERR_OPEN
+                   && notification->error_subcode == BGP_ERR_OPN_UNSUP_PARAM)
+           {
+               LOG(4, 0, 0, "BGP peer %s doesn't support BGP Capabilities\n", peer->name);
+               peer->mp_handling = DoesntHandleIPv6Routes;
+               bgp_restart(peer);
+               return 0;
+           }
+
            if (notification->error_code == BGP_ERR_OPEN
                    && notification->error_subcode == BGP_ERR_OPN_UNSUP_CAP)
            {
@@ -1305,7 +1312,7 @@ static int bgp_handle_input(struct bgp_peer *peer)
                   an "unsupported capability" message, we disable IPv6 routes for
                   this peer */
                LOG(4, 0, 0, "BGP peer %s doesn't support IPv6 routes advertisement\n", peer->name);
-               peer->handle_ipv6_routes = 0;
+               peer->mp_handling = DoesntHandleIPv6Routes;
                break;
            }
 
@@ -1354,20 +1361,28 @@ static int bgp_send_open(struct bgp_peer *peer)
     data.hold_time = htons(peer->hold);
     data.identifier = my_address;
 
-    /* construct the param and capability */
-    cap_mp_ipv6.code = BGP_CAP_CODE_MP;
-    cap_mp_ipv6.len = sizeof(mp_ipv6);
-    memcpy(&cap_mp_ipv6.value, &mp_ipv6, cap_mp_ipv6.len);
+    /* if we know peer doesn't support MP (mp_handling == DoesntHandleIPv6Routes)
+       then don't add this parameter */
+    if (peer->mp_handling == HandlingUnknown
+           || peer->mp_handling == HandleIPv6Routes)
+    {
+       /* construct the param and capability */
+       cap_mp_ipv6.code = BGP_CAP_CODE_MP;
+       cap_mp_ipv6.len = sizeof(mp_ipv6);
+       memcpy(&cap_mp_ipv6.value, &mp_ipv6, cap_mp_ipv6.len);
 
-    param_cap_mp_ipv6.type = BGP_PARAM_TYPE_CAPABILITY;
-    param_cap_mp_ipv6.len = 2 + sizeof(mp_ipv6);
-    memcpy(&param_cap_mp_ipv6.value, &cap_mp_ipv6, param_cap_mp_ipv6.len);
+       param_cap_mp_ipv6.type = BGP_PARAM_TYPE_CAPABILITY;
+       param_cap_mp_ipv6.len = 2 + sizeof(mp_ipv6);
+       memcpy(&param_cap_mp_ipv6.value, &cap_mp_ipv6, param_cap_mp_ipv6.len);
 
-    data.opt_len = 2 + param_cap_mp_ipv6.len;
-    memcpy(&data.opt_params, &param_cap_mp_ipv6, data.opt_len);
+       data.opt_len = 2 + param_cap_mp_ipv6.len;
+       memcpy(&data.opt_params, &param_cap_mp_ipv6, data.opt_len);
+    }
+    else
+       data.opt_len = 0;
 
-    memcpy(peer->outbuf->packet.data, &data, BGP_DATA_OPEN_SIZE);
-    len += BGP_DATA_OPEN_SIZE;
+    memcpy(peer->outbuf->packet.data, &data, BGP_DATA_OPEN_SIZE + data.opt_len);
+    len += BGP_DATA_OPEN_SIZE + data.opt_len;
 
     peer->outbuf->packet.header.len = htons(len);
     peer->outbuf->done = 0;

diff --git a/bgp.h b/bgp.h
index 6dbfbf8..8702838 100644 (file)
--- a/bgp.h
+++ b/bgp.h
@@ -209,6 +209,12 @@ struct bgp_buf {
     size_t done;                       /* bytes sent/recvd */
 };
 
+enum bgp_mp_handling {
+    HandleIPv6Routes,
+    DoesntHandleIPv6Routes,
+    HandlingUnknown,
+};
+
 /* state */
 struct bgp_peer {
     char name[32];                     /* peer name */
@@ -237,7 +243,7 @@ struct bgp_peer {
     int path_attr_len_without_nexthop; /* length of path attrs  without NEXT_HOP */
     uint32_t events;                   /* events to poll */
     struct event_data edata;           /* poll data */
-    int handle_ipv6_routes;            /* can handle IPv6 routes advertisements */
+    enum bgp_mp_handling mp_handling;  /* how it handles IPv6 routes advertisements */
     int update_routes6;                        /* UPDATE required for IPv6 routes */
     struct bgp_route6_list *routes6;   /* IPv6 routes known by this peer */
     char mp_reach_nlri_partial[BGP_PATH_ATTR_MP_REACH_NLRI_PARTIAL_SIZE];