BGP flowspec IPv6 redirect

[rzalamena]

Bug Report

Describe the bug

ExaBGP 3.4.17 works with the following configuration file:

neighbor 10.0.1.1 {
router-id 10.0.1.101;
local-address 10.0.1.101;
local-as 100;
peer-as 100;
flow {
route {
match {
source 1.1.1.2/32;
destination 3.3.3.3/32;
packet-length <200;
}
then {
redirect 50.0.0.2;
rate-limit 55;
}
}
#end route 1
route {
match {
source 1::2/128/0;
destination 3::3/128/0;
packet-length <200;
}
then {
redirect 50::2;
rate-limit 55;
}
}
#end route 2
}
}

(
A bit more of context:

origin: https://github.com/FRRouting/frr/blob/master/tests/topotests/bgp_flowspec/peer1/exabgp.cfg

This is part of the FRR test framework and I'm working on migrating from ExaBGP 3.4 to 4.x.
)

However ExaBGP 4.x has problem parsing that line. I've managed to get it running with the following patch:

--- /usr/local/lib/python3.8/dist-packages/exabgp/configuration/flow/parser.py  2020-11-09 13:23:47.452170848 +0000
+++ /home/rzalamena/exabgp-fixed/configuration/flow/parser.py   2020-11-09 13:20:24.863148297 +0000
@@ -299,8 +299,17 @@
         return NoNextHop, ExtendedCommunities().add(TrafficRedirect(asn, route_target))
     else:
         elements = data.split(':')
-        ip = ':'.join(elements[:-1])
-        asn = int(elements[-1])
+        if count == 2:
+            ip = data
+            return IP.create(ip), ExtendedCommunities().add(TrafficNextHopSimpson(False))
+        else:
+            ip = ':'.join(elements[:-1])
+            asn = int(elements[-1])
+            return IP.create(ip), ExtendedCommunities().add(TrafficRedirectIPv6(ip, asn))

The patch makes FRR's configuration test work, but it is not correct because it assumes IPv6 addresses will only have two ::. I think the more correct fix is to enclose the IPv6 address with something (e.g. [1:2:3:4]:5000) so there is no confusion when using plain IPv6 or when using redirect with ASN/community.

(don't forget to use that patch with these PRs to get it working: #1002 and #1003)

Please let me know what should be the solution here (if there is any). I'm no expert in this so that is why I'm opening this issue.

To Reproduce

Just run exabgp --validate on the configuration above.

Expected behavior

It should work like in ExaBGP 3.4.17.

Environment

• OS: Ubuntu 20.04
• Version: any ExaBGP 4.x

[thomas-mangin]

Yes, I see the point. I will need to patch this on master and the 4.2 branch.

[thomas-mangin]

Thank you - sorry for the time it took me to do this.