flowspec: Add sub-command for FlowSpec with SR Policy

[y-kzm]

This PR adds sub-command for FlowSpec with SR Policy as defined in draft-ietf-idr-ts-flowspec-srv6-policy-05.

• Usage Examples:

  • Option 1: section-5 Fig2

  $ gobgp global rib -a ipv6-flowspec add match destination 2001:db8::/64 then redirect fd00:1::1:0 color 100 prefix 2001:db8:2:2::/64 locator-node-length 24 function-length 16 behavior END_DT6
  $ gobgp global rib -a ipv6-flowspec
     Network                        Next Hop             AS_PATH              Age        Attrs
  *> [destination: 2001:db8::/64/0] fictitious                                00:00:21   [{Origin: ?} {Extcomms: [100]} {Extcomms: [redirect: fd00:1::1:0]} {Prefix SID attributes: {SRv6 L3 Service Attribute: {SRv6 Information Sub TLV: SID: 2001:db8:2:2:: Flag: 0 Endpoint Behavior: 18 {SRv6 Structure Sub Sub TLV: [ Locator Block Length: 64, Locator Node Length: 24, Function Length: 16, Argument Length: 0, Transposition Length: 0, Transposition Offset: 0] } } } }]
  

  • Option 2: section-5 Fig3

  $ gobgp global rib -a ipv6-flowspec add match destination 2001:db8::/64 then redirect fd00:1::1:0 color 100
  $ gobgp global rib -a ipv6-flowspec
     Network                        Next Hop             AS_PATH              Age        Attrs
  *> [destination: 2001:db8::/64/0] fictitious                                00:00:02   [{Origin: ?} {Extcomms: [100]} {Extcomms: [redirect: fd00:1::1:0]}]
  

[y-kzm]

@fujita I've fixed the flowspec error.
But I couldn't find the cause of the error in graceful-restart.
I tried to replicate it locally, but it didn't occur. I think it might be a temporary issue.
Could you rerun the workflow?