The Tcpdump Group git mirrors - tcpdump/blob - print-ip.c

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 #ifndef lint
  23 static const char rcsid[] =
  24     "@(#) $Header: /tcpdump/master/tcpdump/print-ip.c,v 1.80 2000-01-25 01:03:23 fenner Exp $ (LBL)";
  25 #endif
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <sys/param.h>
  32 #include <sys/time.h>
  33 #include <sys/socket.h>
  34
  35 #include <netinet/in.h>
  36 #include <netinet/in_systm.h>
  37 #include <netinet/ip.h>
  38 #include <netinet/ip_var.h>
  39 #include <netinet/udp.h>
  40 #include <netinet/udp_var.h>
  41 #include <netinet/tcp.h>
  42
  43 #ifdef HAVE_MALLOC_H
  44 #include <malloc.h>
  45 #endif
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50
  51 #include "addrtoname.h"
  52 #include "interface.h"
  53 #include "extract.h"                    /* must come after interface.h */
  54
  55 /* Compatibility */
  56 #ifndef IPPROTO_ND
  57 #define IPPROTO_ND      77
  58 #endif
  59
  60 #ifndef IN_CLASSD
  61 #define IN_CLASSD(i) (((int32_t)(i) & 0xf0000000) == 0xe0000000)
  62 #endif
  63
  64 /* (following from ipmulti/mrouted/prune.h) */
  65
  66 /*
  67  * The packet format for a traceroute request.
  68  */
  69 struct tr_query {
  70         u_int  tr_src;                  /* traceroute source */
  71         u_int  tr_dst;                  /* traceroute destination */
  72         u_int  tr_raddr;                /* traceroute response address */
  73         u_int  tr_rttlqid;              /* response ttl and qid */
  74 };
  75
  76 #define TR_GETTTL(x)            (int)(((x) >> 24) & 0xff)
  77 #define TR_GETQID(x)            ((x) & 0x00ffffff)
  78
  79 /*
  80  * Traceroute response format.  A traceroute response has a tr_query at the
  81  * beginning, followed by one tr_resp for each hop taken.
  82  */
  83 struct tr_resp {
  84         u_int tr_qarr;                  /* query arrival time */
  85         u_int tr_inaddr;                /* incoming interface address */
  86         u_int tr_outaddr;               /* outgoing interface address */
  87         u_int tr_rmtaddr;               /* parent address in source tree */
  88         u_int tr_vifin;                 /* input packet count on interface */
  89         u_int tr_vifout;                /* output packet count on interface */
  90         u_int tr_pktcnt;                /* total incoming packets for src-grp */
  91         u_char  tr_rproto;              /* routing proto deployed on router */
  92         u_char  tr_fttl;                /* ttl required to forward on outvif */
  93         u_char  tr_smask;               /* subnet mask for src addr */
  94         u_char  tr_rflags;              /* forwarding error codes */
  95 };
  96
  97 /* defs within mtrace */
  98 #define TR_QUERY 1
  99 #define TR_RESP 2
 100
 101 /* fields for tr_rflags (forwarding error codes) */
 102 #define TR_NO_ERR       0
 103 #define TR_WRONG_IF     1
 104 #define TR_PRUNED       2
 105 #define TR_OPRUNED      3
 106 #define TR_SCOPED       4
 107 #define TR_NO_RTE       5
 108 #define TR_NO_FWD       7
 109 #define TR_NO_SPACE     0x81
 110 #define TR_OLD_ROUTER   0x82
 111
 112 /* fields for tr_rproto (routing protocol) */
 113 #define TR_PROTO_DVMRP  1
 114 #define TR_PROTO_MOSPF  2
 115 #define TR_PROTO_PIM    3
 116 #define TR_PROTO_CBT    4
 117
 118 static void print_mtrace(register const u_char *bp, register u_int len)
 119 {
 120         register struct tr_query *tr = (struct tr_query *)(bp + 8);
 121
 122         printf("mtrace %lu: %s to %s reply-to %s",
 123                 (u_long)TR_GETQID(ntohl(tr->tr_rttlqid)),
 124                 ipaddr_string(&tr->tr_src), ipaddr_string(&tr->tr_dst),
 125                 ipaddr_string(&tr->tr_raddr));
 126         if (IN_CLASSD(ntohl(tr->tr_raddr)))
 127                 printf(" with-ttl %d", TR_GETTTL(ntohl(tr->tr_rttlqid)));
 128 }
 129
 130 static void print_mresp(register const u_char *bp, register u_int len)
 131 {
 132         register struct tr_query *tr = (struct tr_query *)(bp + 8);
 133
 134         printf("mresp %lu: %s to %s reply-to %s",
 135                 (u_long)TR_GETQID(ntohl(tr->tr_rttlqid)),
 136                 ipaddr_string(&tr->tr_src), ipaddr_string(&tr->tr_dst),
 137                 ipaddr_string(&tr->tr_raddr));
 138         if (IN_CLASSD(ntohl(tr->tr_raddr)))
 139                 printf(" with-ttl %d", TR_GETTTL(ntohl(tr->tr_rttlqid)));
 140 }
 141
 142 static void
 143 igmp_print(register const u_char *bp, register u_int len,
 144            register const u_char *bp2)
 145 {
 146         register const struct ip *ip;
 147
 148         ip = (const struct ip *)bp2;
 149         (void)printf("%s > %s: ",
 150                 ipaddr_string(&ip->ip_src),
 151                 ipaddr_string(&ip->ip_dst));
 152
 153         if (qflag) {
 154                 (void)printf("igmp");
 155                 return;
 156         }
 157
 158         TCHECK2(bp[0], 8);
 159         switch (bp[0]) {
 160         case 0x11:
 161                 (void)printf("igmp query");
 162                 if (EXTRACT_32BITS(&bp[4]))
 163                         (void)printf(" [gaddr %s]", ipaddr_string(&bp[4]));
 164                 if (len != 8)
 165                         (void)printf(" [len %d]", len);
 166                 break;
 167         case 0x12:
 168                 (void)printf("igmp v1 report %s", ipaddr_string(&bp[4]));
 169                 if (len != 8)
 170                         (void)printf(" [len %d]", len);
 171                 break;
 172         case 0x16:
 173                 (void)printf("igmp v2 report %s", ipaddr_string(&bp[4]));
 174                 break;
 175         case 0x17:
 176                 (void)printf("igmp leave %s", ipaddr_string(&bp[4]));
 177                 break;
 178         case 0x13:
 179                 (void)printf("igmp dvmrp");
 180                 if (len < 8)
 181                         (void)printf(" [len %d]", len);
 182                 else
 183                         dvmrp_print(bp, len);
 184                 break;
 185         case 0x14:
 186                 (void)printf("igmp pimv1");
 187                 pimv1_print(bp, len);
 188                 break;
 189         case 0x1e:
 190                 print_mresp(bp, len);
 191                 break;
 192         case 0x1f:
 193                 print_mtrace(bp, len);
 194                 break;
 195         default:
 196                 (void)printf("igmp-%d", bp[0]);
 197                 break;
 198         }
 199
 200         if (vflag && TTEST2(bp[0], len)) {
 201                 /* Check the IGMP checksum */
 202                 if (in_cksum((const u_short*)bp, len, 0))
 203                         printf(" bad igmp cksum %x!", EXTRACT_16BITS(&bp[2]));
 204         }
 205         return;
 206 trunc:
 207         fputs("[|igmp]", stdout);
 208 }
 209
 210 /*
 211  * print the recorded route in an IP RR, LSRR or SSRR option.
 212  */
 213 static void
 214 ip_printroute(const char *type, register const u_char *cp, u_int length)
 215 {
 216         register u_int ptr = cp[2] - 1;
 217         register u_int len;
 218
 219         printf(" %s{", type);
 220         if ((length + 1) & 3)
 221                 printf(" [bad length %d]", length);
 222         if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1)
 223                 printf(" [bad ptr %d]", cp[2]);
 224
 225         type = "";
 226         for (len = 3; len < length; len += 4) {
 227                 if (ptr == len)
 228                         type = "#";
 229                 printf("%s%s", type, ipaddr_string(&cp[len]));
 230                 type = " ";
 231         }
 232         printf("%s}", ptr == len? "#" : "");
 233 }
 234
 235 static void
 236 ip_printts(register const u_char *cp, u_int length)
 237 {
 238         register u_int ptr = cp[2] - 1;
 239         register u_int len = 0;
 240         int hoplen;
 241         char *type;
 242
 243         printf(" TS{");
 244         hoplen = ((cp[3]&0xF) != IPOPT_TS_TSONLY) ? 8 : 4;
 245         if ((length - 4) & (hoplen-1))
 246                 printf("[bad length %d]", length);
 247         if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1)
 248                 printf("[bad ptr %d]", cp[2]);
 249         switch (cp[3]&0xF) {
 250         case IPOPT_TS_TSONLY:
 251                 printf("TSONLY");
 252                 break;
 253         case IPOPT_TS_TSANDADDR:
 254                 printf("TS+ADDR");
 255                 break;
 256         /*
 257          * prespecified should really be 3, but some ones might send 2
 258          * instead, and the IPOPT_TS_PRESPEC constant can apparently
 259          * have both values, so we have to hard-code it here.
 260          */
 261
 262         case 2:
 263                 printf("PRESPEC2.0");
 264                 break;
 265         case 3:                 /* IPOPT_TS_PRESPEC */
 266                 printf("PRESPEC");
 267                 break;
 268         default:
 269                 printf("[bad ts type %d]", cp[3]&0xF);
 270                 goto done;
 271         }
 272
 273         type = " ";
 274         for (len = 4; len < length; len += hoplen) {
 275                 if (ptr == len)
 276                         type = " ^ ";
 277                 printf("%s%d@%s", type, EXTRACT_32BITS(&cp[len+hoplen-4]),
 278                        hoplen!=8 ? "" : ipaddr_string(&cp[len]));
 279                 type = " ";
 280         }
 281
 282 done:
 283         printf("%s", ptr == len ? " ^ " : "");
 284
 285         if (cp[3]>>4)
 286                 printf(" [%d hops not recorded]} ", cp[3]>>4);
 287         else
 288                 printf("}");
 289 }
 290
 291 /*
 292  * print IP options.
 293  */
 294 static void
 295 ip_optprint(register const u_char *cp, u_int length)
 296 {
 297         register u_int len;
 298
 299         for (; length > 0; cp += len, length -= len) {
 300                 int tt = *cp;
 301
 302                 len = (tt == IPOPT_NOP || tt == IPOPT_EOL) ? 1 : cp[1];
 303                 if (len <= 0) {
 304                         printf("[|ip op len %d]", len);
 305                         return;
 306                 }
 307                 if (&cp[1] >= snapend || cp + len > snapend) {
 308                         printf("[|ip]");
 309                         return;
 310                 }
 311                 switch (tt) {
 312
 313                 case IPOPT_EOL:
 314                         printf(" EOL");
 315                         if (length > 1)
 316                                 printf("-%d", length - 1);
 317                         return;
 318
 319                 case IPOPT_NOP:
 320                         printf(" NOP");
 321                         break;
 322
 323                 case IPOPT_TS:
 324                         ip_printts(cp, len);
 325                         break;
 326
 327 #ifndef IPOPT_SECURITY
 328 #define IPOPT_SECURITY 130
 329 #endif /* IPOPT_SECURITY */
 330                 case IPOPT_SECURITY:
 331                         printf(" SECURITY{%d}", len);
 332                         break;
 333
 334                 case IPOPT_RR:
 335                         ip_printroute("RR", cp, len);
 336                         break;
 337
 338                 case IPOPT_SSRR:
 339                         ip_printroute("SSRR", cp, len);
 340                         break;
 341
 342                 case IPOPT_LSRR:
 343                         ip_printroute("LSRR", cp, len);
 344                         break;
 345
 346 #ifndef IPOPT_RA
 347 #define IPOPT_RA 148            /* router alert */
 348 #endif
 349                 case IPOPT_RA:
 350                         printf(" RA");
 351                         if (len != 4)
 352                                 printf("{%d}", len);
 353                         else if (cp[2] || cp[3])
 354                                 printf("%d.%d", cp[2], cp[3]);
 355                         break;
 356
 357                 default:
 358                         printf(" IPOPT-%d{%d}", cp[0], len);
 359                         break;
 360                 }
 361         }
 362 }
 363
 364 /*
 365  * compute an IP header checksum.
 366  * don't modifiy the packet.
 367  */
 368 u_short
 369 in_cksum(const u_short *addr, register int len, u_short csum)
 370 {
 371         int nleft = len;
 372         const u_short *w = addr;
 373         u_short answer;
 374         int sum = csum;
 375
 376         /*
 377          *  Our algorithm is simple, using a 32 bit accumulator (sum),
 378          *  we add sequential 16 bit words to it, and at the end, fold
 379          *  back all the carry bits from the top 16 bits into the lower
 380          *  16 bits.
 381          */
 382         while (nleft > 1)  {
 383                 sum += *w++;
 384                 nleft -= 2;
 385         }
 386         if (nleft == 1)
 387                 sum += htons(*(u_char *)w<<8);
 388
 389         /*
 390          * add back carry outs from top 16 bits to low 16 bits
 391          */
 392         sum = (sum >> 16) + (sum & 0xffff);     /* add hi 16 to low 16 */
 393         sum += (sum >> 16);                     /* add carry */
 394         answer = ~sum;                          /* truncate to 16 bits */
 395         return (answer);
 396 }
 397
 398 /*
 399  * print an IP datagram.
 400  */
 401 void
 402 ip_print(register const u_char *bp, register u_int length)
 403 {
 404         register const struct ip *ip;
 405         register u_int hlen, len, len0, off;
 406         register const u_char *cp;
 407         u_char nh;
 408         int advance;
 409
 410         ip = (const struct ip *)bp;
 411 #ifdef LBL_ALIGN
 412         /*
 413          * If the IP header is not aligned, copy into abuf.
 414          * This will never happen with BPF.  It does happen raw packet
 415          * dumps from -r.
 416          */
 417         if ((long)ip & 3) {
 418                 static u_char *abuf = NULL;
 419                 static int didwarn = 0;
 420
 421                 if (abuf == NULL) {
 422                         abuf = (u_char *)malloc(snaplen);
 423                         if (abuf == NULL)
 424                                 error("ip_print: malloc");
 425                 }
 426                 memcpy((char *)abuf, (char *)ip, min(length, snaplen));
 427                 snapend += abuf - (u_char *)ip;
 428                 packetp = abuf;
 429                 ip = (struct ip *)abuf;
 430                 /* We really want libpcap to give us aligned packets */
 431                 if (!didwarn) {
 432                         warning("compensating for unaligned libpcap packets");
 433                         ++didwarn;
 434                 }
 435         }
 436 #endif
 437         if ((u_char *)(ip + 1) > snapend) {
 438                 printf("[|ip]");
 439                 return;
 440         }
 441         if (length < sizeof (struct ip)) {
 442                 (void)printf("truncated-ip %d", length);
 443                 return;
 444         }
 445         hlen = ip->ip_hl * 4;
 446         if (hlen < sizeof (struct ip)) {
 447                 (void)printf("bad-hlen %d", hlen);
 448                 return;
 449         }
 450
 451         len = ntohs(ip->ip_len);
 452         if (length < len)
 453                 (void)printf("truncated-ip - %d bytes missing!",
 454                         len - length);
 455         len -= hlen;
 456         len0 = len;
 457
 458         /*
 459          * If this is fragment zero, hand it to the next higher
 460          * level protocol.
 461          */
 462         off = ntohs(ip->ip_off);
 463         if ((off & 0x1fff) == 0) {
 464                 cp = (const u_char *)ip + hlen;
 465                 nh = ip->ip_p;
 466
 467                 if (nh != IPPROTO_TCP && nh != IPPROTO_UDP) {
 468                         (void)printf("%s > %s: ", ipaddr_string(&ip->ip_src),
 469                                 ipaddr_string(&ip->ip_dst));
 470                 }
 471 again:
 472                 switch (nh) {
 473
 474 #ifndef IPPROTO_AH
 475 #define IPPROTO_AH      51
 476 #endif
 477                 case IPPROTO_AH:
 478                         nh = *cp;
 479                         advance = ah_print(cp, (const u_char *)ip);
 480                         cp += advance;
 481                         len -= advance;
 482                         goto again;
 483
 484 #ifndef IPPROTO_ESP
 485 #define IPPROTO_ESP     50
 486 #endif
 487                 case IPPROTO_ESP:
 488                     {
 489                         int enh;
 490                         advance = esp_print(cp, (const u_char *)ip, &enh);
 491                         cp += advance;
 492                         len -= advance;
 493                         if (enh < 0)
 494                                 break;
 495                         nh = enh & 0xff;
 496                         goto again;
 497                     }
 498
 499 #ifndef IPPROTO_IPCOMP
 500 #define IPPROTO_IPCOMP  108
 501 #endif
 502                 case IPPROTO_IPCOMP:
 503                     {
 504                         int enh;
 505                         advance = ipcomp_print(cp, (const u_char *)ip, &enh);
 506                         cp += advance;
 507                         len -= advance;
 508                         if (enh < 0)
 509                                 break;
 510                         nh = enh & 0xff;
 511                         goto again;
 512                     }
 513
 514                 case IPPROTO_TCP:
 515                         tcp_print(cp, len, (const u_char *)ip);
 516                         break;
 517
 518                 case IPPROTO_UDP:
 519                         udp_print(cp, len, (const u_char *)ip);
 520                         break;
 521
 522                 case IPPROTO_ICMP:
 523                         icmp_print(cp, len, (const u_char *)ip);
 524                         break;
 525
 526 #ifndef IPPROTO_IGRP
 527 #define IPPROTO_IGRP 9
 528 #endif
 529                 case IPPROTO_IGRP:
 530                         igrp_print(cp, len, (const u_char *)ip);
 531                         break;
 532
 533                 case IPPROTO_ND:
 534 #if 0
 535                         (void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
 536                                 ipaddr_string(&ip->ip_dst));
 537 #endif
 538                         (void)printf(" nd %d", len);
 539                         break;
 540
 541                 case IPPROTO_EGP:
 542                         egp_print(cp, len, (const u_char *)ip);
 543                         break;
 544
 545 #ifndef IPPROTO_OSPF
 546 #define IPPROTO_OSPF 89
 547 #endif
 548                 case IPPROTO_OSPF:
 549                         ospf_print(cp, len, (const u_char *)ip);
 550                         break;
 551
 552 #ifndef IPPROTO_IGMP
 553 #define IPPROTO_IGMP 2
 554 #endif
 555                 case IPPROTO_IGMP:
 556                         igmp_print(cp, len, (const u_char *)ip);
 557                         break;
 558
 559                 case 4:
 560                         /* DVMRP multicast tunnel (ip-in-ip encapsulation) */
 561 #if 0
 562                         if (vflag)
 563                                 (void)printf("%s > %s: ",
 564                                              ipaddr_string(&ip->ip_src),
 565                                              ipaddr_string(&ip->ip_dst));
 566 #endif
 567                         ip_print(cp, len);
 568                         if (! vflag) {
 569                                 printf(" (ipip)");
 570                                 return;
 571                         }
 572                         break;
 573
 574 #ifdef INET6
 575 #ifndef IP6PROTO_ENCAP
 576 #define IP6PROTO_ENCAP 41
 577 #endif
 578                 case IP6PROTO_ENCAP:
 579                         /* ip6-in-ip encapsulation */
 580 #if 0
 581                         if (vflag)
 582                                 (void)printf("%s > %s: ",
 583                                              ipaddr_string(&ip->ip_src),
 584                                              ipaddr_string(&ip->ip_dst));
 585 #endif
 586                         ip6_print(cp, len);
 587                         if (! vflag) {
 588                                 printf(" (encap)");
 589                                 return;
 590                         }
 591                         break;
 592 #endif /*INET6*/
 593
 594
 595 #ifndef IPPROTO_GRE
 596 #define IPPROTO_GRE 47
 597 #endif
 598                 case IPPROTO_GRE:
 599                         if (vflag)
 600                                 (void)printf("gre %s > %s: ",
 601                                              ipaddr_string(&ip->ip_src),
 602                                              ipaddr_string(&ip->ip_dst));
 603                         /* do it */
 604                         gre_print(cp, len);
 605                         if (! vflag) {
 606                                 printf(" (gre encap)");
 607                                 return;
 608                         }
 609                         break;
 610
 611 #ifndef IPPROTO_MOBILE
 612 #define IPPROTO_MOBILE 55
 613 #endif
 614                 case IPPROTO_MOBILE:
 615                         if (vflag)
 616                                 (void)printf("mobile %s > %s: ",
 617                                              ipaddr_string(&ip->ip_src),
 618                                              ipaddr_string(&ip->ip_dst));
 619                         mobile_print(cp, len);
 620                         if (! vflag) {
 621                                 printf(" (mobile encap)");
 622                                 return;
 623                         }
 624                         break;
 625
 626 #ifndef IPPROTO_PIM
 627 #define IPPROTO_PIM     103
 628 #endif
 629                 case IPPROTO_PIM:
 630                         pim_print(cp, len);
 631                         break;
 632
 633                 default:
 634 #if 0
 635                         (void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
 636                                 ipaddr_string(&ip->ip_dst));
 637 #endif
 638                         (void)printf(" ip-proto-%d %d", nh, len);
 639                         break;
 640                 }
 641         }
 642
 643         /* Ultra quiet now means that all this stuff should be suppressed */
 644         /* res 3-Nov-98 */
 645         if (qflag > 1) return;
 646
 647
 648         /*
 649          * for fragmented datagrams, print id:size@offset.  On all
 650          * but the last stick a "+".  For unfragmented datagrams, note
 651          * the don't fragment flag.
 652          */
 653         len = len0;     /* get the original length */
 654         if (off & 0x3fff) {
 655                 /*
 656                  * if this isn't the first frag, we're missing the
 657                  * next level protocol header.  print the ip addr.
 658                  */
 659                 if (off & 0x1fff)
 660                         (void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
 661                                       ipaddr_string(&ip->ip_dst));
 662 #ifndef IP_MF
 663 #define IP_MF 0x2000
 664 #endif /* IP_MF */
 665 #ifndef IP_DF
 666 #define IP_DF 0x4000
 667 #endif /* IP_DF */
 668                 (void)printf(" (frag %d:%u@%d%s)", ntohs(ip->ip_id), len,
 669                         (off & 0x1fff) * 8,
 670                         (off & IP_MF)? "+" : "");
 671
 672         } else if (off & IP_DF)
 673                 (void)printf(" (DF)");
 674
 675         if (ip->ip_tos) {
 676                 (void)printf(" [tos 0x%x", (int)ip->ip_tos);
 677                 /* ECN bits */
 678                 if (ip->ip_tos&0x02) {
 679                         (void)printf(",ECT");
 680                         if (ip->ip_tos&0x01)
 681                                 (void)printf(",CE");
 682                 }
 683                 (void)printf("] ");
 684         }
 685
 686         if (ip->ip_ttl <= 1)
 687                 (void)printf(" [ttl %d]", (int)ip->ip_ttl);
 688
 689         if (vflag) {
 690                 int sum;
 691                 char *sep = "";
 692
 693                 printf(" (");
 694                 if (ip->ip_ttl > 1) {
 695                         (void)printf("%sttl %d", sep, (int)ip->ip_ttl);
 696                         sep = ", ";
 697                 }
 698                 if ((off & 0x3fff) == 0) {
 699                         (void)printf("%sid %d", sep, (int)ntohs(ip->ip_id));
 700                         sep = ", ";
 701                 }
 702                 if ((u_char *)ip + hlen <= snapend) {
 703                         sum = in_cksum((const u_short *)ip, hlen, 0);
 704                         if (sum != 0) {
 705                                 (void)printf("%sbad cksum %x!", sep,
 706                                              ntohs(ip->ip_sum));
 707                                 sep = ", ";
 708                         }
 709                 }
 710                 if ((hlen -= sizeof(struct ip)) > 0) {
 711                         (void)printf("%soptlen=%d", sep, hlen);
 712                         ip_optprint((u_char *)(ip + 1), hlen);
 713                 }
 714                 printf(")");
 715         }
 716 }