bgpd: Treat as withdraw if we receive as path with AS_SET / AS_CONFED_SET

For now, only if the knob is enabled. Later this gonna be (most likely) removed
and routes with AS_SET / AS_CONFED_SET will be denied by default.

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>

diff --git a/bgpd/bgp_attr.c b/bgpd/bgp_attr.c
index 0135acec8f300ec0e0ab5fe6d55415a376ca3ea6..d91c717f37cde3e993a5672956ce6d26ae954027 100644 (file)
--- a/bgpd/bgp_attr.c
+++ b/bgpd/bgp_attr.c
@@ -1515,6 +1515,19 @@ static int bgp_attr_aspath(struct bgp_attr_parser_args *args)
                                          0);
        }
 
+       /* Conformant BGP speakers SHOULD NOT send BGP
+        * UPDATE messages containing AS_SET or AS_CONFED_SET.  Upon receipt of
+        * such messages, conformant BGP speakers SHOULD use the "Treat-as-
+        * withdraw" error handling behavior as per [RFC7606].
+        */
+       if (peer->bgp->reject_as_sets && aspath_check_as_sets(attr->aspath)) {
+               flog_err(EC_BGP_ATTR_MAL_AS_PATH,
+                        "AS_SET and AS_CONFED_SET are deprecated from %pBP",
+                        peer);
+               return bgp_attr_malformed(args, BGP_NOTIFY_UPDATE_MAL_AS_PATH,
+                                         0);
+       }
+
        /* Set aspath attribute flag. */
        attr->flag |= ATTR_FLAG_BIT(BGP_ATTR_AS_PATH);
 
@@ -1595,6 +1608,19 @@ static int bgp_attr_as4_path(struct bgp_attr_parser_args *args,
                                          0);
        }
 
+       /* Conformant BGP speakers SHOULD NOT send BGP
+        * UPDATE messages containing AS_SET or AS_CONFED_SET.  Upon receipt of
+        * such messages, conformant BGP speakers SHOULD use the "Treat-as-
+        * withdraw" error handling behavior as per [RFC7606].
+        */
+       if (peer->bgp->reject_as_sets && aspath_check_as_sets(attr->aspath)) {
+               flog_err(EC_BGP_ATTR_MAL_AS_PATH,
+                        "AS_SET and AS_CONFED_SET are deprecated from %pBP",
+                        peer);
+               return bgp_attr_malformed(args, BGP_NOTIFY_UPDATE_MAL_AS_PATH,
+                                         0);
+       }
+
        /* Set aspath attribute flag. */
        attr->flag |= ATTR_FLAG_BIT(BGP_ATTR_AS4_PATH);