BGP: Fix processing of IPv6 Flowspec

During NLRI parsing of IPv6 Flowspec, dst prefix was not properly
extracted from NLRI, therefore a received flow was stored in a different
position in flowspec routing table, and was not reachable by command
'show route <flow>'.

Add proper prefix part accessors to flowspec code and use them from BGP
NLRI parsing code.

Thanks to Alex D. for the bugreport.

1 files changed, 2 insertions, 10 deletions

diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index c3bd600a..0bc63c55 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -1831,13 +1831,9 @@ bgp_decode_nlri_flow4(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
     }
 
     /* Decode dst prefix */
-    ip4_addr px = IP4_NONE;
+    ip4_addr px = flow_read_ip4_part(data);
     uint pxlen = data[1];
 
-    // FIXME: Use some generic function
-    memcpy(&px, data+2, BYTES(pxlen));
-    px = ip4_and(ip4_ntoh(px), ip4_mkmask(pxlen));
-
     /* Prepare the flow */
     net_addr *n = alloca(sizeof(struct net_addr_flow4) + flen);
     net_fill_flow4(n, px, pxlen, pos, flen);
@@ -1923,13 +1919,9 @@ bgp_decode_nlri_flow6(struct bgp_parse_state *s, byte *pos, uint len, rta *a)
     }
 
     /* Decode dst prefix */
-    ip6_addr px = IP6_NONE;
+    ip6_addr px = flow_read_ip6_part(data);
     uint pxlen = data[1];
 
-    // FIXME: Use some generic function
-    memcpy(&px, data+2, BYTES(pxlen));
-    px = ip6_and(ip6_ntoh(px), ip6_mkmask(pxlen));
-
     /* Prepare the flow */
     net_addr *n = alloca(sizeof(struct net_addr_flow6) + flen);
     net_fill_flow6(n, px, pxlen, pos, flen);