}
}
+/*
+ * RFC4684 (Section 4)/RFC2858 (Section 4).
+ * RTC membership prefix is structured as follows
+ * [prefix-len] [origin-as] [route-target]
+ * The route-target is encoded as RT ext-comms.
+ * Prefix-len may be 0, 32..96
+ *
+ * Note that pptr is not packet data - it is
+ * a buffer owned by our caller - therefore GET_*
+ * macros can not be used.
+ */
+static char *
+bgp_rt_prefix_print(netdissect_options *ndo,
+ const u_char *pptr,
+ u_int plen)
+{
+ /* allocate space for the largest possible string */
+ char rtc_prefix_in_hex[20] = "";
+ u_int rtc_prefix_in_hex_len = 0;
+ static char output[60]; /* max response string */
+ uint16_t ec_type = 0;
+ u_int octet_count;
+ u_int i;
+
+ if (plen == 0) {
+ snprintf(output, sizeof(output), "route-target: 0:0/0");
+ return (output);
+ }
+
+ /* hex representation of the prefix */
+ octet_count = (plen+7)/8;
+ for (i=0; i<octet_count; i++) {
+ rtc_prefix_in_hex_len += snprintf(rtc_prefix_in_hex+rtc_prefix_in_hex_len,
+ sizeof(rtc_prefix_in_hex)-rtc_prefix_in_hex_len,
+ "%02x%s", *(pptr+i),
+ ((i%2 == 1) && (i<octet_count-1)) ? " " : "");
+ }
+
+ if (plen < 16) {
+ /*
+ * The prefix is too short to include the full ext-comm type,
+ * so we have no way to parse it further.
+ */
+ snprintf(output, sizeof(output), "route-target: partial-type: (%s/%d)",
+ rtc_prefix_in_hex, plen);
+ return (output);
+ }
+
+ /*
+ * get the ext-comm type
+ * Note: pptr references a static 8 octet buffer with unused bits set to 0,
+ * hense EXTRACT_*() macros are safe.
+ */
+ ec_type = EXTRACT_BE_U_2(pptr);
+ switch (ec_type) {
+ case BGP_EXT_COM_RT_0:
+ /* 2-byte-AS:number fmt */
+ snprintf(output, sizeof(output), "route-target: %u:%u/%d (%s)",
+ EXTRACT_BE_U_2(pptr+2),
+ EXTRACT_BE_U_4(pptr+4),
+ plen, rtc_prefix_in_hex);
+ break;
+
+ case BGP_EXT_COM_RT_1:
+ /* IP-address:AS fmt */
+ snprintf(output, sizeof(output), "route-target: %u.%u.%u.%u:%u/%d (%s)",
+ *(pptr+2), *(pptr+3), *(pptr+4), *(pptr+5),
+ EXTRACT_BE_U_2(pptr+6), plen, rtc_prefix_in_hex);
+ break;
+
+ case BGP_EXT_COM_RT_2:
+ /* 4-byte-AS:number fmt */
+ snprintf(output, sizeof(output), "route-target: %s:%u/%d (%s)",
+ as_printf(ndo, astostr, sizeof(astostr), EXTRACT_BE_U_4(pptr+2)),
+ EXTRACT_BE_U_2(pptr+6), plen, rtc_prefix_in_hex);
+ break;
+
+ default:
+ snprintf(output, sizeof(output), "route target: unknown-type(%04x) (%s/%d)",
+ ec_type,
+ rtc_prefix_in_hex, plen);
+ break;
+ }
+ return (output);
+}
+
/* RFC 4684 */
static int
decode_rt_routing_info(netdissect_options *ndo,
const u_char *pptr)
{
+ uint8_t route_target[8];
u_int plen;
char asbuf[sizeof(astostr)]; /* bgp_vpn_rd_print() overwrites astostr */
+ u_int num_octets;
/* NLRI "prefix length" from RFC 2858 Section 4. */
ND_TCHECK_1(pptr);
plen -= 32; /* adjust prefix length */
- /* An extended community is 8 octets, so the remaining prefix
- * length must be 64.
- */
- if (64 != plen) {
- ND_PRINT("\n\t (illegal prefix length)");
+ if (64 < plen) {
+ ND_PRINT("\n\t (illegal prefix length)");
return -1;
}
- ND_TCHECK_LEN(pptr + 5, 8);
- ND_PRINT("\n\t origin AS: %s, route target ", asbuf);
- bgp_extended_community_print(ndo, pptr + 5);
- return 5 + 8;
+ /* From now on (plen + 7) / 8 evaluates to { 0, 1, 2, ..., 8 }
+ * and gives the number of octets in the variable-length "route
+ * target" field inside this NLRI "prefix". Look for it.
+ */
+ memset(&route_target, 0, sizeof(route_target));
+ num_octets = (plen + 7) / 8;
+ ND_TCHECK_LEN(pptr[5], num_octets);
+ memcpy(&route_target, &pptr[5], num_octets);
+ /* If mask-len is not on octet boundary, ensure all extra bits are 0 */
+ if (plen % 8) {
+ ((u_char *)&route_target)[num_octets - 1] &=
+ ((0xff00 >> (plen % 8)) & 0xff);
+ }
+ ND_PRINT("\n\t origin AS: %s, %s",
+ asbuf,
+ bgp_rt_prefix_print(ndo, (u_char *)&route_target, plen));
+ return 5 + num_octets;
trunc:
return -2;
}
--- /dev/null
+ 1 15:01:45.841851 IP (tos 0x0, ttl 64, id 62521, offset 0, flags [DF], proto TCP (6), length 110)
+ 1.0.0.2.42195 > 1.0.0.1.179: Flags [P.], cksum 0x6f82 (correct), seq 1362195181:1362195239, ack 648591571, win 58, options [nop,nop,TS val 2630416124 ecr 2630387382], length 58: BGP
+ Update Message (2), length: 58
+ Origin (1), length: 1, Flags [T]: EGP
+ AS Path (2), length: 4, Flags [T]: 200
+ Next Hop (3), length: 4, Flags [T]: 0.0.0.0
+ Multi-Protocol Reach NLRI (14), length: 14, Flags [O]:
+ AFI: IPv4 (1), vendor specific SAFI: Route Target Routing Information (132)
+ nexthop: 1.0.0.2, nh-length: 4, no SNPA
+ origin AS: 22, route-target: 0:0/0
+ 2 15:01:45.887255 IP (tos 0xc0, ttl 1, id 16100, offset 0, flags [DF], proto TCP (6), length 52)
+ 1.0.0.1.179 > 1.0.0.2.42195: Flags [.], cksum 0x0391 (correct), ack 58, win 57, options [nop,nop,TS val 2630416135 ecr 2630416124], length 0
+ 3 15:01:45.887452 IP (tos 0x0, ttl 64, id 62522, offset 0, flags [DF], proto TCP (6), length 176)
+ 1.0.0.2.42195 > 1.0.0.1.179: Flags [P.], cksum 0xeffc (correct), seq 58:182, ack 1, win 58, options [nop,nop,TS val 2630416136 ecr 2630416135], length 124: BGP
+ Update Message (2), length: 60
+ Origin (1), length: 1, Flags [T]: EGP
+ AS Path (2), length: 4, Flags [T]: 200
+ Next Hop (3), length: 4, Flags [T]: 0.0.0.0
+ Multi-Protocol Reach NLRI (14), length: 16, Flags [O]:
+ AFI: IPv4 (1), vendor specific SAFI: Route Target Routing Information (132)
+ nexthop: 1.0.0.2, nh-length: 4, no SNPA
+ origin AS: 22, route-target: 0:0/16 (0002)
+ Update Message (2), length: 64
+ Origin (1), length: 1, Flags [T]: EGP
+ AS Path (2), length: 4, Flags [T]: 200
+ Next Hop (3), length: 4, Flags [T]: 0.0.0.0
+ Multi-Protocol Reach NLRI (14), length: 20, Flags [O]:
+ AFI: IPv4 (1), vendor specific SAFI: Route Target Routing Information (132)
+ nexthop: 1.0.0.2, nh-length: 4, no SNPA
+ origin AS: 22, route-target: 65536:0/48 (0202 0001 0000)
+ 4 15:01:45.887461 IP (tos 0xc0, ttl 1, id 16101, offset 0, flags [DF], proto TCP (6), length 52)
+ 1.0.0.1.179 > 1.0.0.2.42195: Flags [.], cksum 0x0308 (correct), ack 182, win 57, options [nop,nop,TS val 2630416136 ecr 2630416136], length 0
+ 5 15:01:45.902997 IP (tos 0x0, ttl 64, id 62523, offset 0, flags [DF], proto TCP (6), length 118)
+ 1.0.0.2.42195 > 1.0.0.1.179: Flags [P.], cksum 0xf60d (correct), seq 182:248, ack 1, win 58, options [nop,nop,TS val 2630416139 ecr 2630416136], length 66: BGP
+ Update Message (2), length: 66
+ Origin (1), length: 1, Flags [T]: EGP
+ AS Path (2), length: 4, Flags [T]: 200
+ Next Hop (3), length: 4, Flags [T]: 0.0.0.0
+ Multi-Protocol Reach NLRI (14), length: 22, Flags [O]:
+ AFI: IPv4 (1), vendor specific SAFI: Route Target Routing Information (132)
+ nexthop: 1.0.0.2, nh-length: 4, no SNPA
+ origin AS: 22, route-target: 1:65537/64 (0002 0001 0001 0001)
+ 6 15:01:45.903022 IP (tos 0xc0, ttl 1, id 16102, offset 0, flags [DF], proto TCP (6), length 52)
+ 1.0.0.1.179 > 1.0.0.2.42195: Flags [.], cksum 0x02c0 (correct), ack 248, win 57, options [nop,nop,TS val 2630416139 ecr 2630416139], length 0
+ 7 15:01:45.922092 IP (tos 0x0, ttl 64, id 62524, offset 0, flags [DF], proto TCP (6), length 118)
+ 1.0.0.2.42195 > 1.0.0.1.179: Flags [P.], cksum 0x6d25 (correct), seq 248:314, ack 1, win 58, options [nop,nop,TS val 2630416144 ecr 2630416139], length 66: BGP
+ Update Message (2), length: 66
+ Origin (1), length: 1, Flags [T]: EGP
+ AS Path (2), length: 4, Flags [T]: 200
+ Next Hop (3), length: 4, Flags [T]: 0.0.0.0
+ Multi-Protocol Reach NLRI (14), length: 22, Flags [O]:
+ AFI: IPv4 (1), vendor specific SAFI: Route Target Routing Information (132)
+ nexthop: 1.0.0.2, nh-length: 4, no SNPA
+ origin AS: 22, route-target: 100000:65535/64 (0202 0001 86a0 ffff)
+ 8 15:01:45.922106 IP (tos 0xc0, ttl 1, id 16103, offset 0, flags [DF], proto TCP (6), length 52)
+ 1.0.0.1.179 > 1.0.0.2.42195: Flags [.], cksum 0x0274 (correct), ack 314, win 57, options [nop,nop,TS val 2630416144 ecr 2630416144], length 0
+ 9 15:01:45.945988 IP (tos 0x0, ttl 64, id 62525, offset 0, flags [DF], proto TCP (6), length 106)
+ 1.0.0.2.42195 > 1.0.0.1.179: Flags [P.], cksum 0x00d3 (correct), seq 314:368, ack 1, win 58, options [nop,nop,TS val 2630416150 ecr 2630416144], length 54: BGP
+ Update Message (2), length: 54
+ Origin (1), length: 1, Flags [T]: EGP
+ AS Path (2), length: 4, Flags [T]: 200
+ Next Hop (3), length: 4, Flags [T]: 0.0.0.0
+ Multi-Protocol Unreach NLRI (15), length: 10, Flags [O]:
+ AFI: IPv4 (1), vendor specific SAFI: Route Target Routing Information (132)
+ origin AS: 23, route-target: 0.0.0.0:0/16 (0102)
+ 10 15:01:45.946014 IP (tos 0xc0, ttl 1, id 16104, offset 0, flags [DF], proto TCP (6), length 52)
+ 1.0.0.1.179 > 1.0.0.2.42195: Flags [.], cksum 0x0232 (correct), ack 368, win 57, options [nop,nop,TS val 2630416150 ecr 2630416150], length 0
+ 11 15:01:45.972778 IP (tos 0x0, ttl 64, id 62526, offset 0, flags [DF], proto TCP (6), length 111)
+ 1.0.0.2.42195 > 1.0.0.1.179: Flags [P.], cksum 0x1757 (correct), seq 368:427, ack 1, win 58, options [nop,nop,TS val 2630416157 ecr 2630416150], length 59: BGP
+ Update Message (2), length: 59
+ Origin (1), length: 1, Flags [T]: EGP
+ AS Path (2), length: 4, Flags [T]: 200
+ Next Hop (3), length: 4, Flags [T]: 0.0.0.0
+ Multi-Protocol Unreach NLRI (15), length: 15, Flags [O]:
+ AFI: IPv4 (1), vendor specific SAFI: Route Target Routing Information (132)
+ origin AS: 23, route-target: 1.2.3.4:57344/51 (0102 0102 0304 e0)
+ 12 15:01:45.972789 IP (tos 0xc0, ttl 1, id 16105, offset 0, flags [DF], proto TCP (6), length 52)
+ 1.0.0.1.179 > 1.0.0.2.42195: Flags [.], cksum 0x01e9 (correct), ack 427, win 57, options [nop,nop,TS val 2630416157 ecr 2630416157], length 0
+ 13 15:01:45.997647 IP (tos 0x0, ttl 64, id 62527, offset 0, flags [DF], proto TCP (6), length 112)
+ 1.0.0.2.42195 > 1.0.0.1.179: Flags [P.], cksum 0xf5ff (correct), seq 427:487, ack 1, win 58, options [nop,nop,TS val 2630416163 ecr 2630416157], length 60: BGP
+ Update Message (2), length: 60
+ Origin (1), length: 1, Flags [T]: EGP
+ AS Path (2), length: 4, Flags [T]: 200
+ Next Hop (3), length: 4, Flags [T]: 0.0.0.0
+ Multi-Protocol Unreach NLRI (15), length: 16, Flags [O]:
+ AFI: IPv4 (1), vendor specific SAFI: Route Target Routing Information (132)
+ origin AS: 23, route-target: 1.2.3.4:65535/64 (0102 0102 0304 ffff)
+ 14 15:01:45.997673 IP (tos 0xc0, ttl 1, id 16106, offset 0, flags [DF], proto TCP (6), length 52)
+ 1.0.0.1.179 > 1.0.0.2.42195: Flags [.], cksum 0x01a1 (correct), ack 487, win 57, options [nop,nop,TS val 2630416163 ecr 2630416163], length 0
projects / tcpdump / commitdiff
