/* $NetBSD: print-ip.c,v 1.6 2004/09/27 23:04:24 dyoung Exp $ */ /* * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that: (1) source code distributions * retain the above copyright notice and this paragraph in its entirety, (2) * distributions including binary code include the above copyright notice and * this paragraph in its entirety in the documentation or other materials * provided with the distribution, and (3) all advertising materials mentioning * features or use of this software display the following acknowledgement: * ``This product includes software developed by the University of California, * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of * the University nor the names of its contributors may be used to endorse * or promote products derived from this software without specific prior * written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ #include #ifndef lint #if 0 static const char rcsid[] _U_ = "@(#) Header: /tcpdump/master/tcpdump/print-ip.c,v 1.128.2.6 2004/03/24 09:01:39 guy Exp (LBL)"; #else __RCSID("$NetBSD: print-ip.c,v 1.6 2004/09/27 23:04:24 dyoung Exp $"); #endif #endif #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include #include "addrtoname.h" #include "interface.h" #include "extract.h" /* must come after interface.h */ #include "ip.h" #include "ipproto.h" /* * print the recorded route in an IP RR, LSRR or SSRR option. */ static void ip_printroute(const char *type, register const u_char *cp, u_int length) { register u_int ptr; register u_int len; if (length < 3) { printf(" [bad length %u]", length); return; } printf(" %s{", type); if ((length + 1) & 3) printf(" [bad length %u]", length); ptr = cp[2] - 1; if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1) printf(" [bad ptr %u]", cp[2]); type = ""; for (len = 3; len < length; len += 4) { if (ptr == len) type = "#"; printf("%s%s", type, ipaddr_string(&cp[len])); type = " "; } printf("%s}", ptr == len? "#" : ""); } /* * If source-routing is present, return the final destination. * Otherwise, return IP destination. * * This is used for UDP and TCP pseudo-header in the checksum * calculation. */ u_int32_t ip_finddst(const struct ip *ip) { int length; int len; const u_char *cp; u_int32_t retval; cp = (const u_char *)(ip + 1); length = (IP_HL(ip) << 2) - sizeof(struct ip); for (; length > 0; cp += len, length -= len) { int tt; TCHECK(*cp); tt = *cp; if (tt == IPOPT_NOP || tt == IPOPT_EOL) len = 1; else { TCHECK(cp[1]); len = cp[1]; } if (len < 2) { return 0; } TCHECK2(*cp, len); switch (tt) { case IPOPT_SSRR: case IPOPT_LSRR: if (len < 7) return 0; memcpy(&retval, cp + len - 4, 4); return retval; } } return ip->ip_dst.s_addr; trunc: return 0; } static void ip_printts(register const u_char *cp, u_int length) { register u_int ptr; register u_int len; int hoplen; const char *type; if (length < 4) { printf("[bad length %d]", length); return; } printf(" TS{"); hoplen = ((cp[3]&0xF) != IPOPT_TS_TSONLY) ? 8 : 4; if ((length - 4) & (hoplen-1)) printf("[bad length %d]", length); ptr = cp[2] - 1; len = 0; if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1) printf("[bad ptr %d]", cp[2]); switch (cp[3]&0xF) { case IPOPT_TS_TSONLY: printf("TSONLY"); break; case IPOPT_TS_TSANDADDR: printf("TS+ADDR"); break; /* * prespecified should really be 3, but some ones might send 2 * instead, and the IPOPT_TS_PRESPEC constant can apparently * have both values, so we have to hard-code it here. */ case 2: printf("PRESPEC2.0"); break; case 3: /* IPOPT_TS_PRESPEC */ printf("PRESPEC"); break; default: printf("[bad ts type %d]", cp[3]&0xF); goto done; } type = " "; for (len = 4; len < length; len += hoplen) { if (ptr == len) type = " ^ "; printf("%s%d@%s", type, EXTRACT_32BITS(&cp[len+hoplen-4]), hoplen!=8 ? "" : ipaddr_string(&cp[len])); type = " "; } done: printf("%s", ptr == len ? " ^ " : ""); if (cp[3]>>4) printf(" [%d hops not recorded]} ", cp[3]>>4); else printf("}"); } /* * print IP options. */ static void ip_optprint(register const u_char *cp, u_int length) { register u_int len; for (; length > 0; cp += len, length -= len) { int tt; TCHECK(*cp); tt = *cp; if (tt == IPOPT_NOP || tt == IPOPT_EOL) len = 1; else { TCHECK(cp[1]); len = cp[1]; if (len < 2) { printf("[|ip op len %d]", len); return; } TCHECK2(*cp, len); } switch (tt) { case IPOPT_EOL: printf(" EOL"); if (length > 1) printf("-%d", length - 1); return; case IPOPT_NOP: printf(" NOP"); break; case IPOPT_TS: ip_printts(cp, len); break; #ifndef IPOPT_SECURITY #define IPOPT_SECURITY 130 #endif /* IPOPT_SECURITY */ case IPOPT_SECURITY: printf(" SECURITY{%d}", len); break; case IPOPT_RR: ip_printroute("RR", cp, len); break; case IPOPT_SSRR: ip_printroute("SSRR", cp, len); break; case IPOPT_LSRR: ip_printroute("LSRR", cp, len); break; #ifndef IPOPT_RA #define IPOPT_RA 148 /* router alert */ #endif case IPOPT_RA: printf(" RA"); if (len != 4) printf("{%d}", len); else { TCHECK(cp[3]); if (cp[2] || cp[3]) printf("%d.%d", cp[2], cp[3]); } break; default: printf(" IPOPT-%d{%d}", cp[0], len); break; } } return; trunc: printf("[|ip]"); } /* * compute an IP header checksum. * don't modifiy the packet. */ u_short in_cksum(const u_short *addr, register u_int len, int csum) { int nleft = len; const u_short *w = addr; u_short answer; int sum = csum; /* * Our algorithm is simple, using a 32 bit accumulator (sum), * we add sequential 16 bit words to it, and at the end, fold * back all the carry bits from the top 16 bits into the lower * 16 bits. */ while (nleft > 1) { sum += *w++; nleft -= 2; } if (nleft == 1) sum += htons(*(u_char *)w<<8); /* * add back carry outs from top 16 bits to low 16 bits */ sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ sum += (sum >> 16); /* add carry */ answer = ~sum; /* truncate to 16 bits */ return (answer); } /* * Given the host-byte-order value of the checksum field in a packet * header, and the network-byte-order computed checksum of the data * that the checksum covers (including the checksum itself), compute * what the checksum field *should* have been. */ u_int16_t in_cksum_shouldbe(u_int16_t sum, u_int16_t computed_sum) { u_int32_t shouldbe; /* * The value that should have gone into the checksum field * is the negative of the value gotten by summing up everything * *but* the checksum field. * * We can compute that by subtracting the value of the checksum * field from the sum of all the data in the packet, and then * computing the negative of that value. * * "sum" is the value of the checksum field, and "computed_sum" * is the negative of the sum of all the data in the packets, * so that's -(-computed_sum - sum), or (sum + computed_sum). * * All the arithmetic in question is one's complement, so the * addition must include an end-around carry; we do this by * doing the arithmetic in 32 bits (with no sign-extension), * and then adding the upper 16 bits of the sum, which contain * the carry, to the lower 16 bits of the sum, and then do it * again in case *that* sum produced a carry. * * As RFC 1071 notes, the checksum can be computed without * byte-swapping the 16-bit words; summing 16-bit words * on a big-endian machine gives a big-endian checksum, which * can be directly stuffed into the big-endian checksum fields * in protocol headers, and summing words on a little-endian * machine gives a little-endian checksum, which must be * byte-swapped before being stuffed into a big-endian checksum * field. * * "computed_sum" is a network-byte-order value, so we must put * it in host byte order before subtracting it from the * host-byte-order value from the header; the adjusted checksum * will be in host byte order, which is what we'll return. */ shouldbe = sum; shouldbe += ntohs(computed_sum); shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16); shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16); return shouldbe; } #ifndef IP_MF #define IP_MF 0x2000 #endif /* IP_MF */ #ifndef IP_DF #define IP_DF 0x4000 #endif /* IP_DF */ #define IP_RES 0x8000 static struct tok ip_frag_values[] = { { IP_MF, "+" }, { IP_DF, "DF" }, { IP_RES, "rsvd" }, /* The RFC3514 evil ;-) bit */ { 0, NULL } }; /* * print an IP datagram. */ void ip_print(register const u_char *bp, register u_int length) { register const struct ip *ip; register u_int hlen, len, len0, off; const u_char *ipend; register const u_char *cp; u_char nh; int advance; struct protoent *proto; u_int16_t sum, ip_sum; ip = (const struct ip *)bp; if (IP_V(ip) != 4) { /* print version if != 4 */ printf("IP%u ", IP_V(ip)); if (IP_V(ip) == 6) printf(", wrong link-layer encapsulation"); } else printf("IP "); if ((u_char *)(ip + 1) > snapend) { printf("[|ip]"); return; } if (length < sizeof (struct ip)) { (void)printf("truncated-ip %d", length); return; } hlen = IP_HL(ip) * 4; if (hlen < sizeof (struct ip)) { (void)printf("bad-hlen %u", hlen); return; } len = EXTRACT_16BITS(&ip->ip_len); if (length < len) (void)printf("truncated-ip - %u bytes missing! ", len - length); if (len < hlen) { (void)printf("bad-len %u", len); return; } /* * Cut off the snapshot length to the end of the IP payload. */ ipend = bp + len; if (ipend < snapend) snapend = ipend; len -= hlen; len0 = len; off = EXTRACT_16BITS(&ip->ip_off); if (vflag) { (void)printf("(tos 0x%x", (int)ip->ip_tos); /* ECN bits */ if (ip->ip_tos & 0x03) { switch (ip->ip_tos & 0x03) { case 1: (void)printf(",ECT(1)"); break; case 2: (void)printf(",ECT(0)"); break; case 3: (void)printf(",CE"); } } if (ip->ip_ttl >= 1) (void)printf(", ttl %3u", ip->ip_ttl); /* * for the firewall guys, print id, offset. * On all but the last stick a "+" in the flags portion. * For unfragmented datagrams, note the don't fragment flag. */ (void)printf(", id %u, offset %u, flags [%s]", EXTRACT_16BITS(&ip->ip_id), (off & 0x1fff) * 8, bittok2str(ip_frag_values, "none", off & 0xe000 )); (void)printf(", length: %u", EXTRACT_16BITS(&ip->ip_len)); if ((hlen - sizeof(struct ip)) > 0) { (void)printf(", optlength: %u (", hlen - (u_int)sizeof(struct ip)); ip_optprint((u_char *)(ip + 1), hlen - sizeof(struct ip)); printf(" )"); } if ((u_char *)ip + hlen <= snapend) { sum = in_cksum((const u_short *)ip, hlen, 0); if (sum != 0) { ip_sum = EXTRACT_16BITS(&ip->ip_sum); (void)printf(", bad cksum %x (->%x)!", ip_sum, in_cksum_shouldbe(ip_sum, sum)); } } printf(") "); } /* * If this is fragment zero, hand it to the next higher * level protocol. */ if ((off & 0x1fff) == 0) { cp = (const u_char *)ip + hlen; nh = ip->ip_p; if (nh != IPPROTO_TCP && nh != IPPROTO_UDP && nh != IPPROTO_SCTP) { (void)printf("%s > %s: ", ipaddr_string(&ip->ip_src), ipaddr_string(&ip->ip_dst)); } again: switch (nh) { case IPPROTO_AH: nh = *cp; advance = ah_print(cp); if (advance <= 0) break; cp += advance; len -= advance; goto again; case IPPROTO_ESP: { int enh, padlen; advance = esp_print(cp, (const u_char *)ip, &enh, &padlen); if (advance <= 0) break; cp += advance; len -= advance + padlen; nh = enh & 0xff; goto again; } case IPPROTO_IPCOMP: { int enh; advance = ipcomp_print(cp, &enh); if (advance <= 0) break; cp += advance; len -= advance; nh = enh & 0xff; goto again; } case IPPROTO_SCTP: sctp_print(cp, (const u_char *)ip, len); break; case IPPROTO_TCP: tcp_print(cp, len, (const u_char *)ip, (off &~ 0x6000)); break; case IPPROTO_UDP: udp_print(cp, len, (const u_char *)ip, (off &~ 0x6000)); break; case IPPROTO_ICMP: /* pass on the MF bit plus the offset to detect fragments */ icmp_print(cp, len, (const u_char *)ip, (off & 0x3fff)); break; case IPPROTO_IGRP: igrp_print(cp, len, (const u_char *)ip); break; case IPPROTO_ND: (void)printf(" nd %d", len); break; case IPPROTO_EGP: egp_print(cp); break; case IPPROTO_OSPF: ospf_print(cp, len, (const u_char *)ip); break; case IPPROTO_IGMP: igmp_print(cp, len); break; case IPPROTO_IPV4: /* DVMRP multicast tunnel (ip-in-ip encapsulation) */ ip_print(cp, len); if (! vflag) { printf(" (ipip-proto-4)"); return; } break; #ifdef INET6 case IPPROTO_IPV6: /* ip6-in-ip encapsulation */ ip6_print(cp, len); break; #endif /*INET6*/ case IPPROTO_RSVP: rsvp_print(cp, len); break; case IPPROTO_GRE: /* do it */ gre_print(cp, len); break; case IPPROTO_MOBILE: mobile_print(cp, len); break; case IPPROTO_PIM: pim_print(cp, len); break; case IPPROTO_VRRP: vrrp_print(cp, len, ip->ip_ttl); break; default: if ((proto = getprotobynumber(nh)) != NULL) (void)printf(" %s", proto->p_name); else (void)printf(" ip-proto-%d", nh); printf(" %d", len); break; } } else { /* Ultra quiet now means that all this stuff should be suppressed */ if (qflag > 1) return; /* * if this isn't the first frag, we're missing the * next level protocol header. print the ip addr * and the protocol. */ if (off & 0x1fff) { (void)printf("%s > %s:", ipaddr_string(&ip->ip_src), ipaddr_string(&ip->ip_dst)); if ((proto = getprotobynumber(ip->ip_p)) != NULL) (void)printf(" %s", proto->p_name); else (void)printf(" ip-proto-%d", ip->ip_p); } } } void ipN_print(register const u_char *bp, register u_int length) { struct ip *ip, hdr; ip = (struct ip *)bp; if (length < 4) { (void)printf("truncated-ip %d", length); return; } memcpy (&hdr, (char *)ip, 4); switch (IP_V(&hdr)) { case 4: ip_print (bp, length); return; #ifdef INET6 case 6: ip6_print (bp, length); return; #endif default: (void)printf("unknown ip %d", IP_V(&hdr)); return; } }