print-bgp.c

来自「TCPDUMP的C语言源代码,是在数据链路层的应用」· C语言 代码 · 共 1,792 行 · 第 1/5 页

	if (152 < plen)
		return -1;

	memset(&addr, 0, sizeof(addr));
	TCHECK2(pptr[12], (plen + 7) / 8);
	memcpy(&addr, &pptr[12], (plen + 7) / 8);
	if (plen % 8) {
		addr[(plen + 7) / 8 - 1] &=
			((0xff00 >> (plen % 8)) & 0xff);
	}
        /* the label may get offsetted by 4 bits so lets shift it right */
	snprintf(buf, buflen, "RD: %s, %s/%d, label:%u %s",
                 bgp_vpn_rd_print(pptr+4),
                 isonsap_string(addr,(plen + 7) / 8),
                 plen,
                 EXTRACT_24BITS(pptr+1)>>4,
                 ((pptr[3]&1)==0) ? "(BOGUS: Bottom of Stack NOT set!)" : "(bottom)" );

	return 12 + (plen + 7) / 8;

trunc:
	return -2;
}

/*
 * bgp_attr_get_as_size
 *
 * Try to find the size of the ASs encoded in an as-path. It is not obvious, as
 * both Old speakers that do not support 4 byte AS, and the new speakers that do
 * support, exchange AS-Path with the same path-attribute type value 0x02.
 */
static int
bgp_attr_get_as_size (u_int8_t bgpa_type, const u_char *pptr, int len)
{
    const u_char *tptr = pptr;

    /*
     * If the path attribute is the optional AS4 path type, then we already
     * know, that ASs must be encoded in 4 byte format.
     */
    if (bgpa_type == BGPTYPE_AS4_PATH) {
        return 4;
    }

    /*
     * Let us assume that ASs are of 2 bytes in size, and check if the AS-Path
     * TLV is good. If not, ask the caller to try with AS encoded as 4 bytes
     * each.
     */
    while (tptr < pptr + len) {
        TCHECK(tptr[0]);

        /*
         * If we do not find a valid segment type, our guess might be wrong.
         */
        if (tptr[0] < BGP_AS_SEG_TYPE_MIN || tptr[0] > BGP_AS_SEG_TYPE_MAX) {
            goto trunc;
        }
        TCHECK(tptr[1]);
        tptr += 2 + tptr[1] * 2;
    }

    /*
     * If we correctly reached end of the AS path attribute data content,
     * then most likely ASs were indeed encoded as 2 bytes.
     */
    if (tptr == pptr + len) {
        return 2;
    }

trunc:

    /*
     * We can come here, either we did not have enough data, or if we
     * try to decode 4 byte ASs in 2 byte format. Either way, return 4,
     * so that calller can try to decode each AS as of 4 bytes. If indeed
     * there was not enough data, it will crib and end the parse anyways.
     */
   return 4;
}

static int
bgp_attr_print(const struct bgp_attr *attr, const u_char *pptr, int len)
{
	int i;
	u_int16_t af;
	u_int8_t safi, snpa, nhlen;
        union { /* copy buffer for bandwidth values */
            float f; 
            u_int32_t i;
        } bw;
	int advance;
	int tlen;
	const u_char *tptr;
	char buf[MAXHOSTNAMELEN + 100];
	char tokbuf[TOKBUFSIZE];
        int  as_size;

        tptr = pptr;
        tlen=len;

	switch (attr->bgpa_type) {
	case BGPTYPE_ORIGIN:
		if (len != 1)
			printf("invalid len");
		else {
			TCHECK(*tptr);
			printf("%s", tok2strbuf(bgp_origin_values,
						"Unknown Origin Typecode",
						tptr[0],
						tokbuf, sizeof(tokbuf)));
		}
		break;


        /*
         * Process AS4 byte path and AS2 byte path attributes here.
         */
	case BGPTYPE_AS4_PATH:
	case BGPTYPE_AS_PATH:
		if (len % 2) {
			printf("invalid len");
			break;
		}
                if (!len) {
			printf("empty");
			break;
                }

                /*
                 * BGP updates exchanged between New speakers that support 4
                 * byte AS, ASs are always encoded in 4 bytes. There is no
                 * definitive way to find this, just by the packet's
                 * contents. So, check for packet's TLV's sanity assuming
                 * 2 bytes first, and it does not pass, assume that ASs are
                 * encoded in 4 bytes format and move on.
                 */
                as_size = bgp_attr_get_as_size(attr->bgpa_type, pptr, len);

		while (tptr < pptr + len) {
			TCHECK(tptr[0]);
                        printf("%s", tok2strbuf(bgp_as_path_segment_open_values,
						"?", tptr[0],
						tokbuf, sizeof(tokbuf)));
                        for (i = 0; i < tptr[1] * as_size; i += as_size) {
                            TCHECK2(tptr[2 + i], as_size);
                            printf("%u ",
                                   as_size == 2 ?  EXTRACT_16BITS(&tptr[2 + i]) :
                                                   EXTRACT_32BITS(&tptr[2 + i]));
                        }
			TCHECK(tptr[0]);
                        printf("%s", tok2strbuf(bgp_as_path_segment_close_values,
						"?", tptr[0],
						tokbuf, sizeof(tokbuf)));
                        TCHECK(tptr[1]);
                        tptr += 2 + tptr[1] * as_size;
		}
		break;
	case BGPTYPE_NEXT_HOP:
		if (len != 4)
			printf("invalid len");
		else {
			TCHECK2(tptr[0], 4);
			printf("%s", getname(tptr));
		}
		break;
	case BGPTYPE_MULTI_EXIT_DISC:
	case BGPTYPE_LOCAL_PREF:
		if (len != 4)
			printf("invalid len");
		else {
			TCHECK2(tptr[0], 4);
			printf("%u", EXTRACT_32BITS(tptr));
		}
		break;
	case BGPTYPE_ATOMIC_AGGREGATE:
		if (len != 0)
			printf("invalid len");
		break;
	case BGPTYPE_AGGREGATOR:
		if (len != 6) {
			printf("invalid len");
			break;
		}
		TCHECK2(tptr[0], 6);
		printf(" AS #%u, origin %s", EXTRACT_16BITS(tptr),
			getname(tptr + 2));
		break;
	case BGPTYPE_AGGREGATOR4:
		if (len != 8) {
			printf("invalid len");
			break;
		}
		TCHECK2(tptr[0], 8);
		printf(" AS #%u, origin %s", EXTRACT_32BITS(tptr),
			getname(tptr + 4));
		break;
	case BGPTYPE_COMMUNITIES:
		if (len % 4) {
			printf("invalid len");
			break;
		}
		while (tlen>0) {
			u_int32_t comm;
			TCHECK2(tptr[0], 4);
			comm = EXTRACT_32BITS(tptr);
			switch (comm) {
			case BGP_COMMUNITY_NO_EXPORT:
				printf(" NO_EXPORT");
				break;
			case BGP_COMMUNITY_NO_ADVERT:
				printf(" NO_ADVERTISE");
				break;
			case BGP_COMMUNITY_NO_EXPORT_SUBCONFED:
				printf(" NO_EXPORT_SUBCONFED");
				break;
			default:
				printf("%u:%u%s",
                                       (comm >> 16) & 0xffff,
                                       comm & 0xffff,
                                       (tlen>4) ? ", " : "");
				break;
			}
                        tlen -=4;
                        tptr +=4;
		}
		break;
        case BGPTYPE_ORIGINATOR_ID:
		if (len != 4) {
			printf("invalid len");
			break;
		}
		TCHECK2(tptr[0], 4);
                printf("%s",getname(tptr));
                break;
        case BGPTYPE_CLUSTER_LIST:
		if (len % 4) {
			printf("invalid len");
			break;
		}
                while (tlen>0) {
			TCHECK2(tptr[0], 4);
                        printf("%s%s",
                               getname(tptr),
                                (tlen>4) ? ", " : "");
                        tlen -=4;
                        tptr +=4;
                }
                break;
	case BGPTYPE_MP_REACH_NLRI:
		TCHECK2(tptr[0], 3);
		af = EXTRACT_16BITS(tptr);
		safi = tptr[2];
	
                printf("\n\t    AFI: %s (%u), %sSAFI: %s (%u)",
                       tok2strbuf(af_values, "Unknown AFI", af,
				  tokbuf, sizeof(tokbuf)),
                       af,
                       (safi>128) ? "vendor specific " : "", /* 128 is meanwhile wellknown */
                       tok2strbuf(bgp_safi_values, "Unknown SAFI", safi,
				  tokbuf, sizeof(tokbuf)),
                       safi);

                switch(af<<8 | safi) {
                case (AFNUM_INET<<8 | SAFNUM_UNICAST):
                case (AFNUM_INET<<8 | SAFNUM_MULTICAST):
                case (AFNUM_INET<<8 | SAFNUM_UNIMULTICAST):
                case (AFNUM_INET<<8 | SAFNUM_LABUNICAST):
                case (AFNUM_INET<<8 | SAFNUM_RT_ROUTING_INFO):
                case (AFNUM_INET<<8 | SAFNUM_VPNUNICAST):
                case (AFNUM_INET<<8 | SAFNUM_VPNMULTICAST):
                case (AFNUM_INET<<8 | SAFNUM_VPNUNIMULTICAST):
                case (AFNUM_INET<<8 | SAFNUM_MULTICAST_VPN):
#ifdef INET6
                case (AFNUM_INET6<<8 | SAFNUM_UNICAST):
                case (AFNUM_INET6<<8 | SAFNUM_MULTICAST):
                case (AFNUM_INET6<<8 | SAFNUM_UNIMULTICAST):
                case (AFNUM_INET6<<8 | SAFNUM_LABUNICAST):
                case (AFNUM_INET6<<8 | SAFNUM_VPNUNICAST):
                case (AFNUM_INET6<<8 | SAFNUM_VPNMULTICAST):
                case (AFNUM_INET6<<8 | SAFNUM_VPNUNIMULTICAST):
#endif
                case (AFNUM_NSAP<<8 | SAFNUM_UNICAST):
                case (AFNUM_NSAP<<8 | SAFNUM_MULTICAST):
                case (AFNUM_NSAP<<8 | SAFNUM_UNIMULTICAST):
                case (AFNUM_NSAP<<8 | SAFNUM_VPNUNICAST):
                case (AFNUM_NSAP<<8 | SAFNUM_VPNMULTICAST):
                case (AFNUM_NSAP<<8 | SAFNUM_VPNUNIMULTICAST):
                case (AFNUM_L2VPN<<8 | SAFNUM_VPNUNICAST):
                case (AFNUM_L2VPN<<8 | SAFNUM_VPNMULTICAST):
                case (AFNUM_L2VPN<<8 | SAFNUM_VPNUNIMULTICAST):
                case (AFNUM_VPLS<<8 | SAFNUM_VPLS):
                    break;
                default:
                    TCHECK2(tptr[0], tlen);
                    printf("\n\t    no AFI %u / SAFI %u decoder",af,safi);
                    if (vflag <= 1)
                        print_unknown_data(tptr,"\n\t    ",tlen);
                    goto done;
                    break;
                }

                tptr +=3;

		TCHECK(tptr[0]);
		nhlen = tptr[0];
                tlen = nhlen;
                tptr++;

		if (tlen) {
                    printf("\n\t    nexthop: ");
                    while (tlen > 0) {
                        switch(af<<8 | safi) {
                        case (AFNUM_INET<<8 | SAFNUM_UNICAST):
                        case (AFNUM_INET<<8 | SAFNUM_MULTICAST):
                        case (AFNUM_INET<<8 | SAFNUM_UNIMULTICAST):
                        case (AFNUM_INET<<8 | SAFNUM_LABUNICAST):
                        case (AFNUM_INET<<8 | SAFNUM_RT_ROUTING_INFO):
                        case (AFNUM_INET<<8 | SAFNUM_MULTICAST_VPN):
                            if (tlen < (int)sizeof(struct in_addr)) {
                                printf("invalid len");
                                tlen = 0;
                            } else {
                                TCHECK2(tptr[0], sizeof(struct in_addr));
                                printf("%s",getname(tptr));
                                tlen -= sizeof(struct in_addr);
                                tptr += sizeof(struct in_addr);
                            }
                            break;
                        case (AFNUM_INET<<8 | SAFNUM_VPNUNICAST):
                        case (AFNUM_INET<<8 | SAFNUM_VPNMULTICAST):
                        case (AFNUM_INET<<8 | SAFNUM_VPNUNIMULTICAST):
                            if (tlen < (int)(sizeof(struct in_addr)+BGP_VPN_RD_LEN)) {
                                printf("invalid len");
                                tlen = 0;
                            } else {
                                TCHECK2(tptr[0], sizeof(struct in_addr)+BGP_VPN_RD_LEN);
                                printf("RD: %s, %s",
                                       bgp_vpn_rd_print(tptr),
                                       getname(tptr+BGP_VPN_RD_LEN));
                                tlen -= (sizeof(struct in_addr)+BGP_VPN_RD_LEN);
                                tptr += (sizeof(struct in_addr)+BGP_VPN_RD_LEN);
                            }
                            break;
#ifdef INET6
                        case (AFNUM_INET6<<8 | SAFNUM_UNICAST):
                        case (AFNUM_INET6<<8 | SAFNUM_MULTICAST):
                        case (AFNUM_INET6<<8 | SAFNUM_UNIMULTICAST):
                        case (AFNUM_INET6<<8 | SAFNUM_LABUNICAST):
                            if (tlen < (int)sizeof(struct in6_addr)) {
                                printf("invalid len");
                                tlen = 0;
                            } else {
                                TCHECK2(tptr[0], sizeof(struct in6_addr));
                                printf("%s", getname6(tptr));
                                tlen -= sizeof(struct in6_addr);
                                tptr += sizeof(struct in6_addr);
                            }