On Fri, Oct 14, 2016 at 10:44:33AM +0200, Peter Hessler wrote:
> While working on Large Communities, I realized that I would really like
> to easily see and know when I am receiving "unknown" attributes.
>
> Patch for tcpdump is easy, if it doesn't have a decoder, just print the
> type and length. You can use -X to see the raw hex.
>
> Path for bgpctl is a bit more involved. This shows us the type, flags,
> len and if len is not zero, the local-endian hex dump.
>
> OK?
>
>
> Example tcpdump:
> BGP (UPDATE: (Path attributes: (ORIGIN[T] IGP)
> (AS_PATH[T] 65000)
> (NEXT_HOP[T] 192.168.50.62)
> (#30[OTP] unknown type 30 len:24))
> (NLRI: 1.2.3.4/32)) (DF) (ttl 64, id 14847, len 127)
>
> Example bgpctl:
>
> BGP routing table entry for 72.10.114.0/24
> 29140 2603 11164 22742
> Nexthop 172.16.255.1 (via 172.16.255.1) from 172.16.255.1 (217.31.95.174)
> Origin IGP, metric 0, localpref 100, weight 0, external, valid, best
> Last update: 2d15h36m ago
> Communities: 2603:302 2603:501 2603:11164 2603:64110 2603:64113
> 11164:1160 11164:7500 11164:51240 11164:52100 11164:52200
> Ext. communities: rt 2603:434300002, rt 22742:777
> Unknown Attribute #20 flags [OTP] len 14: 00 01 00 00 58 d6 00 00 02 8e
> cf d2 8d b5
>
>
>
> Index: usr.sbin/tcpdump/print-bgp.c
> ===================================================================
> RCS file: /cvs/openbsd/src/usr.sbin/tcpdump/print-bgp.c,v
> retrieving revision 1.19
> diff -u -p -u -p -r1.19 print-bgp.c
> --- usr.sbin/tcpdump/print-bgp.c 13 Oct 2016 08:48:15 -0000 1.19
> +++ usr.sbin/tcpdump/print-bgp.c 14 Oct 2016 08:39:04 -0000
> @@ -713,6 +713,7 @@ bgp_attr_print(const struct bgp_attr *at
> }
> break;
> default:
> + printf(" unknown type %u len %u", attr->bgpa_type, len);
> break;
> }
> return 1;
> Index: usr.sbin/bgpctl/bgpctl.c
> ===================================================================
> RCS file: /cvs/openbsd/src/usr.sbin/bgpctl/bgpctl.c,v
> retrieving revision 1.188
> diff -u -p -u -p -r1.188 bgpctl.c
> --- usr.sbin/bgpctl/bgpctl.c 3 Jun 2016 17:36:37 -0000 1.188
> +++ usr.sbin/bgpctl/bgpctl.c 14 Oct 2016 08:30:44 -0000
> @@ -1393,6 +1393,7 @@ show_attr(void *b, u_int16_t len)
> u_int32_t as;
> u_int16_t alen, ioff;
> u_int8_t flags, type;
> + int i;
>
> if (len < 3)
> errx(1, "show_attr: too short bgp attr");
> @@ -1448,8 +1449,29 @@ show_attr(void *b, u_int16_t len)
> show_ext_community(data, alen);
> printf("\n");
> break;
> + case ATTR_ATOMIC_AGGREGATE:
> + /* ignore */
> + break;
> default:
> /* ignore unknown attributes */
> + printf(" Unknown Attribute #%u", type);
> + if (flags) {
> + printf(" flags [");
> + if (flags & ATTR_OPTIONAL)
> + printf("O");
> + if (flags & ATTR_TRANSITIVE)
> + printf("T");
> + if (flags & ATTR_PARTIAL)
> + printf("P");
> + printf("]");
> + }
> + printf(" len %u", alen);
> + if (alen) {
> + printf(":");
> + for (i=0; i < alen; i++)
> + printf(" %02x", *(data+i) & 0xFF);
> + }
> + printf("\n");
> break;
> }
> }
>
>
bgpctl diff OK claudio@. For tcpdump I think it is a good start but it
would be nice to dump more info as well (like the flags and maybe even the
data).
--
:wq Claudio
