bgp: ignore link-local address

According to RFC 2545, both a global address and a link-local address
can be sent as a next_hop address in BGPUpdate message.
Since the link-local address is not needed in Ryu BGP,
Ryu BGP ignore it if the address family is IPv6 unicast.

Signed-off-by: Hiroshi Yokoi <yokoi.hiroshi@po.ntts.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

1 files changed, 10 insertions, 0 deletions

diff --git a/ryu/lib/packet/bgp.py b/ryu/lib/packet/bgp.py
index 60e3b49c..ff6d7afe 100644
--- a/ryu/lib/packet/bgp.py
+++ b/ryu/lib/packet/bgp.py
@@ -2014,6 +2014,16 @@ class BGPPathAttributeMpReachNLRI(_PathAttribute):
         elif afi == addr_family.IP:
             next_hop = addrconv.ipv4.bin_to_text(next_hop_bin)
         elif afi == addr_family.IP6:
+            # next_hop_bin can include global address and link-local address
+            # according to RFC2545. Since a link-local address isn't needed in
+            # Ryu BGPSpeaker, we ignore it if both addresses were sent.
+            # The link-local address is supposed to follow after
+            # a global address and next_hop_len will be 32 bytes,
+            # so we use the first 16 bytes, which is a global address,
+            # as a next_hop and change the next_hop_len to 16.
+            if next_hop_len == 32:
+                next_hop_bin = next_hop_bin[:16]
+                next_hop_len = 16
             next_hop = addrconv.ipv6.bin_to_text(next_hop_bin)
         else:
             raise ValueError('Invalid address familly(%d)' % afi)