X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/b751376719cfe1924aa07ab8fd364ec1a55c04b3..296d466cd6bbf2f7e75e15bb6a01268e88c76ed0:/print-icmp.c diff --git a/print-icmp.c b/print-icmp.c index 2c4dde25..9b53a48a 100644 --- a/print-icmp.c +++ b/print-icmp.c @@ -21,9 +21,7 @@ /* \summary: Internet Control Message Protocol (ICMP) printer */ -#ifdef HAVE_CONFIG_H #include -#endif #include "netdissect-stdinc.h" @@ -86,13 +84,10 @@ struct icmp { #define icmp_data icmp_dun.id_data }; -#define ICMP_MPLS_EXT_EXTRACT_VERSION(x) (((x)&0xf0)>>4) -#define ICMP_MPLS_EXT_VERSION 2 - /* * Lower bounds on packet lengths for various types. * For the error advice packets must first insure that the - * packet is large enought to contain the returned ip header. + * packet is large enough to contain the returned ip header. * Only then can we do the check to see if 64 bits of packet * data have been returned, since we need to check the returned * ip header length. @@ -150,7 +145,7 @@ struct icmp { ((type) == ICMP_UNREACH || (type) == ICMP_SOURCEQUENCH || \ (type) == ICMP_REDIRECT || (type) == ICMP_TIMXCEED || \ (type) == ICMP_PARAMPROB) -#define ICMP_MPLS_EXT_TYPE(type) \ +#define ICMP_MULTIPART_EXT_TYPE(type) \ ((type) == ICMP_UNREACH || \ (type) == ICMP_TIMXCEED || \ (type) == ICMP_PARAMPROB) @@ -221,13 +216,17 @@ struct id_rdiscovery { }; /* - * draft-bonica-internet-icmp-08 + * RFC 4884 - Extended ICMP to Support Multi-Part Messages + * + * This is a general extension mechanism, based on the mechanism + * in draft-bonica-icmp-mpls-02 ICMP Extensions for MultiProtocol + * Label Switching. * * The Destination Unreachable, Time Exceeded * and Parameter Problem messages are slightly changed as per - * the above draft. A new Length field gets added to give - * the caller an idea about the length of the piggypacked - * IP packet before the MPLS extension header starts. + * the above RFC. A new Length field gets added to give + * the caller an idea about the length of the piggybacked + * IP packet before the extension header starts. * * The Length field represents length of the padded "original datagram" * field measured in 32-bit words. @@ -259,15 +258,34 @@ struct icmp_ext_t { nd_byte icmp_ext_data[1]; }; -struct icmp_mpls_ext_object_header_t { +/* + * Extract version from the first octet of icmp_ext_version_res. + */ +#define ICMP_EXT_EXTRACT_VERSION(x) (((x)&0xf0)>>4) + +/* + * Current version. + */ +#define ICMP_EXT_VERSION 2 + +/* + * Extension object class numbers. + * + * Class 1 dates back to draft-bonica-icmp-mpls-02. + */ + +/* rfc4950 */ +#define MPLS_STACK_ENTRY_OBJECT_CLASS 1 + +struct icmp_multipart_ext_object_header_t { nd_uint16_t length; nd_uint8_t class_num; nd_uint8_t ctype; }; -static const struct tok icmp_mpls_ext_obj_values[] = { +static const struct tok icmp_multipart_ext_obj_values[] = { { 1, "MPLS Stack Entry" }, - { 2, "Extended Payload" }, + { 2, "Interface Identification" }, { 0, NULL} }; @@ -305,8 +323,7 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * const struct udphdr *ouh; const uint8_t *obj_tptr; uint32_t raw_label; - const u_char *snapend_save; - const struct icmp_mpls_ext_object_header_t *icmp_mpls_ext_object_header; + const struct icmp_multipart_ext_object_header_t *icmp_multipart_ext_object_header; u_int hlen, mtu, obj_tlen, obj_class_num, obj_ctype; uint16_t dport; char buf[MAXHOSTNAMELEN + 100]; @@ -318,14 +335,12 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * ip = (const struct ip *)bp2; str = buf; - ND_TCHECK_1(dp->icmp_code); icmp_type = GET_U_1(dp->icmp_type); icmp_code = GET_U_1(dp->icmp_code); switch (icmp_type) { case ICMP_ECHO: case ICMP_ECHOREPLY: - ND_TCHECK_2(dp->icmp_seq); (void)snprintf(buf, sizeof(buf), "echo %s, id %u, seq %u", icmp_type == ICMP_ECHO ? "request" : "reply", @@ -334,7 +349,6 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * break; case ICMP_UNREACH: - ND_TCHECK_4(dp->icmp_ip.ip_dst); switch (icmp_code) { case ICMP_UNREACH_NET: @@ -350,7 +364,6 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * break; case ICMP_UNREACH_PROTOCOL: - ND_TCHECK_1(dp->icmp_ip.ip_p); (void)snprintf(buf, sizeof(buf), "%s protocol %u unreachable", GET_IPADDR_STRING(dp->icmp_ip.ip_dst), @@ -362,7 +375,6 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * oip = &dp->icmp_ip; hlen = IP_HL(oip) * 4; ouh = (const struct udphdr *)(((const u_char *)oip) + hlen); - ND_TCHECK_2(ouh->uh_dport); dport = GET_BE_U_2(ouh->uh_dport); ip_proto = GET_U_1(oip->ip_p); switch (ip_proto) { @@ -483,7 +495,6 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * break; case ICMP_REDIRECT: - ND_TCHECK_4(dp->icmp_ip.ip_dst); switch (icmp_code) { case ICMP_REDIRECT_NET: @@ -599,7 +610,6 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * (void)snprintf(buf, sizeof(buf), "parameter problem - code %u", icmp_code); else { - ND_TCHECK_1(dp->icmp_pptr); (void)snprintf(buf, sizeof(buf), "parameter problem - octet %u", GET_U_1(dp->icmp_pptr)); @@ -607,13 +617,11 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * break; case ICMP_MASKREPLY: - ND_TCHECK_4(dp->icmp_mask); (void)snprintf(buf, sizeof(buf), "address mask is 0x%08x", GET_BE_U_4(dp->icmp_mask)); break; case ICMP_TSTAMP: - ND_TCHECK_2(dp->icmp_seq); (void)snprintf(buf, sizeof(buf), "time stamp query id %u seq %u", GET_BE_U_2(dp->icmp_id), @@ -657,30 +665,42 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * /* * print the remnants of the IP packet. - * save the snaplength as this may get overidden in the IP printer. + * save the snaplength as this may get overridden in the IP printer. */ if (ndo->ndo_vflag >= 1 && ICMP_ERRTYPE(icmp_type)) { + const u_char *snapend_save; + bp += 8; ND_PRINT("\n\t"); ip = (const struct ip *)bp; - snapend_save = ndo->ndo_snapend; - ND_TCHECK_2(ip->ip_len); + snapend_save = ndo->ndo_snapend; + /* + * Update the snapend because extensions (MPLS, ...) may be + * present after the IP packet. In this case the current + * (outer) packet's snapend is not what ip_print() needs to + * decode an IP packet nested in the middle of an ICMP payload. + * + * This prevents that, in ip_print(), for the nested IP packet, + * the remaining length < remaining caplen. + */ + ndo->ndo_snapend = ND_MIN(bp + GET_BE_U_2(ip->ip_len), + ndo->ndo_snapend); ip_print(ndo, bp, GET_BE_U_2(ip->ip_len)); - ndo->ndo_snapend = snapend_save; + ndo->ndo_snapend = snapend_save; } /* ndo_protocol reassignment after ip_print() call */ ndo->ndo_protocol = "icmp"; /* - * Attempt to decode the MPLS extensions only for some ICMP types. + * Attempt to decode multi-part message extensions (rfc4884) only for some ICMP types. */ - if (ndo->ndo_vflag >= 1 && plen > ICMP_EXTD_MINLEN && ICMP_MPLS_EXT_TYPE(icmp_type)) { + if (ndo->ndo_vflag >= 1 && plen > ICMP_EXTD_MINLEN && ICMP_MULTIPART_EXT_TYPE(icmp_type)) { ND_TCHECK_SIZE(ext_dp); /* - * Check first if the mpls extension header shows a non-zero length. + * Check first if the multi-part extension header shows a non-zero length. * If the length field is not set then silently verify the checksum * to check if an extension header is present. This is expedient, * however not all implementations set the length field proper. @@ -694,14 +714,14 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * } } - ND_PRINT("\n\tMPLS extension v%u", - ICMP_MPLS_EXT_EXTRACT_VERSION(*(ext_dp->icmp_ext_version_res))); + ND_PRINT("\n\tICMP Multi-Part extension v%u", + ICMP_EXT_EXTRACT_VERSION(*(ext_dp->icmp_ext_version_res))); /* * Sanity checking of the header. */ - if (ICMP_MPLS_EXT_EXTRACT_VERSION(*(ext_dp->icmp_ext_version_res)) != - ICMP_MPLS_EXT_VERSION) { + if (ICMP_EXT_EXTRACT_VERSION(*(ext_dp->icmp_ext_version_res)) != + ICMP_EXT_VERSION) { ND_PRINT(" packet not supported"); return; } @@ -719,37 +739,36 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * hlen -= 4; /* subtract common header size */ obj_tptr = (const uint8_t *)ext_dp->icmp_ext_data; - while (hlen > sizeof(struct icmp_mpls_ext_object_header_t)) { + while (hlen > sizeof(struct icmp_multipart_ext_object_header_t)) { - icmp_mpls_ext_object_header = (const struct icmp_mpls_ext_object_header_t *)obj_tptr; - ND_TCHECK_SIZE(icmp_mpls_ext_object_header); - obj_tlen = GET_BE_U_2(icmp_mpls_ext_object_header->length); - obj_class_num = GET_U_1(icmp_mpls_ext_object_header->class_num); - obj_ctype = GET_U_1(icmp_mpls_ext_object_header->ctype); - obj_tptr += sizeof(struct icmp_mpls_ext_object_header_t); + icmp_multipart_ext_object_header = (const struct icmp_multipart_ext_object_header_t *)obj_tptr; + ND_TCHECK_SIZE(icmp_multipart_ext_object_header); + obj_tlen = GET_BE_U_2(icmp_multipart_ext_object_header->length); + obj_class_num = GET_U_1(icmp_multipart_ext_object_header->class_num); + obj_ctype = GET_U_1(icmp_multipart_ext_object_header->ctype); + obj_tptr += sizeof(struct icmp_multipart_ext_object_header_t); ND_PRINT("\n\t %s Object (%u), Class-Type: %u, length %u", - tok2str(icmp_mpls_ext_obj_values,"unknown",obj_class_num), + tok2str(icmp_multipart_ext_obj_values,"unknown",obj_class_num), obj_class_num, obj_ctype, obj_tlen); - hlen-=sizeof(struct icmp_mpls_ext_object_header_t); /* length field includes tlv header */ + hlen-=sizeof(struct icmp_multipart_ext_object_header_t); /* length field includes tlv header */ /* infinite loop protection */ if ((obj_class_num == 0) || - (obj_tlen < sizeof(struct icmp_mpls_ext_object_header_t))) { + (obj_tlen < sizeof(struct icmp_multipart_ext_object_header_t))) { return; } - obj_tlen-=sizeof(struct icmp_mpls_ext_object_header_t); + obj_tlen-=sizeof(struct icmp_multipart_ext_object_header_t); switch (obj_class_num) { - case 1: + case MPLS_STACK_ENTRY_OBJECT_CLASS: switch(obj_ctype) { case 1: - ND_TCHECK_4(obj_tptr); raw_label = GET_BE_U_4(obj_tptr); - ND_PRINT("\n\t label %u, exp %u", MPLS_LABEL(raw_label), MPLS_EXP(raw_label)); + ND_PRINT("\n\t label %u, tc %u", MPLS_LABEL(raw_label), MPLS_TC(raw_label)); if (MPLS_STACK(raw_label)) ND_PRINT(", [S]"); ND_PRINT(", ttl %u", MPLS_TTL(raw_label)); @@ -759,11 +778,6 @@ icmp_print(netdissect_options *ndo, const u_char *bp, u_int plen, const u_char * } break; - /* - * FIXME those are the defined objects that lack a decoder - * you are welcome to contribute code ;-) - */ - case 2: default: print_unknown_data(ndo, obj_tptr, "\n\t ", obj_tlen); break;