package/network/services/dnsmasq/patches/0004-Add-packet-dump-debugging-facility.patch

   1 From 6b17335209639a56f214d011eaed4ebcde8dd276 Mon Sep 17 00:00:00 2001
   2 From: Simon Kelley <simon@thekelleys.org.uk>
   3 Date: Tue, 8 May 2018 18:32:14 +0100
   4 Subject: [PATCH 04/10] Add packet-dump debugging facility.
   5
   6 Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
   7 ---
   8  CHANGELOG      |   6 ++
   9  Makefile       |   2 +-
  10  bld/Android.mk |   3 +-
  11  man/dnsmasq.8  |   7 ++
  12  src/config.h   |  16 ++++-
  13  src/dnsmasq.c  |  16 ++++-
  14  src/dnsmasq.h  |  29 +++++++-
  15  src/dump.c     | 210 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  16  src/forward.c  |  37 ++++++++--
  17  src/option.c   |  14 ++++
  18  10 files changed, 329 insertions(+), 11 deletions(-)
  19  create mode 100644 src/dump.c
  20
  21 --- a/CHANGELOG
  22 +++ b/CHANGELOG
  23 @@ -17,6 +17,12 @@ version 2.80
  24          Fix DHCP broken-ness when --no-ping AND --dhcp-sequential-ip
  25         are set. Thanks to Daniel Miess for help with this.
  26
  27 +       Add a facilty to store DNS packets sent/recieved in a
  28 +       pcap-format file for later debugging. The file location
  29 +       is given by the --dumpfile option, and a bitmap controlling
  30 +       which packets should be dumped is given by the --dumpmask
  31 +       option.
  32 +
  33
  34  version 2.79
  35         Fix parsing of CNAME arguments, which are confused by extra spaces.
  36 --- a/Makefile
  37 +++ b/Makefile
  38 @@ -76,7 +76,7 @@ objs = cache.o rfc1035.o util.o option.o
  39         helper.o tftp.o log.o conntrack.o dhcp6.o rfc3315.o \
  40         dhcp-common.o outpacket.o radv.o slaac.o auth.o ipset.o \
  41         domain.o dnssec.o blockdata.o tables.o loop.o inotify.o \
  42 -       poll.o rrfilter.o edns0.o arp.o crypto.o
  43 +       poll.o rrfilter.o edns0.o arp.o crypto.o dump.o
  44
  45  hdrs = dnsmasq.h config.h dhcp-protocol.h dhcp6-protocol.h \
  46         dns-protocol.h radv-protocol.h ip6addr.h
  47 --- a/bld/Android.mk
  48 +++ b/bld/Android.mk
  49 @@ -10,7 +10,8 @@ LOCAL_SRC_FILES :=  bpf.c cache.c dbus.c
  50                     dhcp6.c rfc3315.c dhcp-common.c outpacket.c \
  51                     radv.c slaac.c auth.c ipset.c domain.c \
  52                     dnssec.c dnssec-openssl.c blockdata.c tables.c \
  53 -                   loop.c inotify.c poll.c rrfilter.c edns0.c arp.c crypto.c
  54 +                   loop.c inotify.c poll.c rrfilter.c edns0.c arp.c \
  55 +                   crypto.c dump.c
  56
  57  LOCAL_MODULE := dnsmasq
  58
  59 --- a/man/dnsmasq.8
  60 +++ b/man/dnsmasq.8
  61 @@ -647,6 +647,13 @@ V4 mapped IPv6 addresses, which have a r
  62  The address range can be of the form
  63  <ip address>,<ip address> or <ip address>/<netmask> in both forms of the option.
  64  .TP
  65 +.B --dumpfile=<path/to/file>
  66 +Specify the location of a pcap-format file which dnsmasq uses to dump copies of network packets for debugging purposes. If the file exists when dnsmasq starts, it is not deleted; new packets are added to the end.
  67 +.TP
  68 +.B --dumpmask=<mask>
  69 +Specify which types of packets should be added to the dumpfile. The argument should be the OR of the bitmasks for each type of packet to be dumped: it can be specified in hex by preceding the number with 0x in  the normal way. Each time a packet is written to the dumpfile, dnsmasq logs the packet sequence and the mask
  70 +representing its type. The current types are: 0x0001 - DNS queries from clients 0x0002 DNS replies to clients 0x0004 - DNS queries to upstream 0x0008 - DNS replies from upstream 0x0010 - queries send upstream for DNSSEC validation 0x0020 - replies to queries for DNSSEC validation 0x0040 - replies to client queries which fail DNSSEC validation 0x0080 replies to queries for DNSSEC validation which fail validation.
  71 +.TP
  72  .B --add-mac[=base64|text]
  73  Add the MAC address of the requestor to DNS queries which are
  74  forwarded upstream. This may be used to DNS filtering by the upstream
  75 --- a/src/config.h
  76 +++ b/src/config.h
  77 @@ -117,6 +117,9 @@ HAVE_AUTH
  78  HAVE_DNSSEC
  79     include DNSSEC validator.
  80
  81 +HAVE_DUMPFILE
  82 +   include code to dump packets to a libpcap-format file for debugging.
  83 +
  84  HAVE_LOOP
  85     include functionality to probe for and remove DNS forwarding loops.
  86
  87 @@ -132,6 +135,7 @@ NO_DHCP6
  88  NO_SCRIPT
  89  NO_LARGEFILE
  90  NO_AUTH
  91 +NO_DUMPFILE
  92  NO_INOTIFY
  93     these are available to explicitly disable compile time options which would
  94     otherwise be enabled automatically (HAVE_IPV6, >2Gb file sizes) or
  95 @@ -164,6 +168,7 @@ RESOLVFILE
  96  #define HAVE_AUTH
  97  #define HAVE_IPSET
  98  #define HAVE_LOOP
  99 +#define HAVE_DUMPFILE
 100
 101  /* Build options which require external libraries.
 102
 103 @@ -363,6 +368,10 @@ HAVE_SOCKADDR_SA_LEN
 104  #undef HAVE_LOOP
 105  #endif
 106
 107 +#ifdef NO_DUMPFILE
 108 +#undef HAVE_DUMPFILE
 109 +#endif
 110 +
 111  #if defined (HAVE_LINUX_NETWORK) && !defined(NO_INOTIFY)
 112  #define HAVE_INOTIFY
 113  #endif
 114 @@ -451,8 +460,11 @@ static char *compile_opts =
 115  #ifndef HAVE_INOTIFY
 116  "no-"
 117  #endif
 118 -"inotify";
 119 -
 120 +"inotify "
 121 +#ifndef HAVE_DUMPFILE
 122 +"no-"
 123 +#endif
 124 +"dumpfile";
 125
 126  #endif
 127
 128 --- a/src/dnsmasq.c
 129 +++ b/src/dnsmasq.c
 130 @@ -366,7 +366,16 @@ int main (int argc, char **argv)
 131    else
 132      daemon->inotifyfd = -1;
 133  #endif
 134 -
 135 +
 136 +  if (daemon->dump_file)
 137 +#ifdef HAVE_DUMPFILE
 138 +    dump_init();
 139 +  else
 140 +    daemon->dumpfd = -1;
 141 +#else
 142 +  die(_("Packet dumps not available: set HAVE_DUMP in src/config.h"), NULL, EC_BADCONF);
 143 +#endif
 144 +
 145    if (option_bool(OPT_DBUS))
 146  #ifdef HAVE_DBUS
 147      {
 148 @@ -1424,6 +1433,11 @@ static void async_event(int pipe, time_t
 149
 150         if (daemon->runfile)
 151           unlink(daemon->runfile);
 152 +
 153 +#ifdef HAVE_DUMPFILE
 154 +       if (daemon->dumpfd != -1)
 155 +         close(daemon->dumpfd);
 156 +#endif
 157
 158         my_syslog(LOG_INFO, _("exiting on receipt of SIGTERM"));
 159         flush_log();
 160 --- a/src/dnsmasq.h
 161 +++ b/src/dnsmasq.h
 162 @@ -119,6 +119,9 @@ typedef unsigned long long u64;
 163  #include <net/if_arp.h>
 164  #include <netinet/in_systm.h>
 165  #include <netinet/ip.h>
 166 +#ifdef HAVE_IPV6
 167 +#include <netinet/ip6.h>
 168 +#endif
 169  #include <netinet/ip_icmp.h>
 170  #include <sys/uio.h>
 171  #include <syslog.h>
 172 @@ -598,6 +601,16 @@ struct hostsfile {
 173    unsigned int index; /* matches to cache entries for logging */
 174  };
 175
 176 +/* packet-dump flags */
 177 +#define DUMP_QUERY     0x0001
 178 +#define DUMP_REPLY     0x0002
 179 +#define DUMP_UP_QUERY  0x0004
 180 +#define DUMP_UP_REPLY  0x0008
 181 +#define DUMP_SEC_QUERY 0x0010
 182 +#define DUMP_SEC_REPLY 0x0020
 183 +#define DUMP_BOGUS     0x0040
 184 +#define DUMP_SEC_BOGUS 0x0080
 185 +
 186
 187  /* DNSSEC status values. */
 188  #define STAT_SECURE             1
 189 @@ -1020,14 +1033,14 @@ extern struct daemon {
 190    unsigned int duid_enterprise, duid_config_len;
 191    unsigned char *duid_config;
 192    char *dbus_name;
 193 +  char *dump_file;
 194 +  int dump_mask;
 195    unsigned long soa_sn, soa_refresh, soa_retry, soa_expiry;
 196  #ifdef OPTION6_PREFIX_CLASS
 197    struct prefix_class *prefix_classes;
 198  #endif
 199  #ifdef HAVE_DNSSEC
 200    struct ds_config *ds;
 201 -  int dnssec_no_time_check;
 202 -  int back_to_the_future;
 203    char *timestamp_file;
 204  #endif
 205
 206 @@ -1040,6 +1053,8 @@ extern struct daemon {
 207    char *workspacename; /* ditto */
 208    char *rr_status; /* flags for individual RRs */
 209    int rr_status_sz;
 210 +  int dnssec_no_time_check;
 211 +  int back_to_the_future;
 212  #endif
 213    unsigned int local_answer, queries_forwarded, auth_answer;
 214    struct frec *frec_list;
 215 @@ -1094,6 +1109,10 @@ extern struct daemon {
 216    char *addrbuff;
 217    char *addrbuff2; /* only allocated when OPT_EXTRALOG */
 218
 219 +#ifdef HAVE_DUMPFILE
 220 +  /* file for packet dumps. */
 221 +  int dumpfd;
 222 +#endif
 223  } *daemon;
 224
 225  /* cache.c */
 226 @@ -1588,3 +1607,9 @@ int check_source(struct dns_header *head
 227  /* arp.c */
 228  int find_mac(union mysockaddr *addr, unsigned char *mac, int lazy, time_t now);
 229  int do_arp_script_run(void);
 230 +
 231 +/* dump.c */
 232 +#ifdef HAVE_DUMPFILE
 233 +void dump_init(void);
 234 +void dump_packet(int mask, void *packet, size_t len, union mysockaddr *src, union mysockaddr *dst);
 235 +#endif
 236 --- /dev/null
 237 +++ b/src/dump.c
 238 @@ -0,0 +1,210 @@
 239 +/* dnsmasq is Copyright (c) 2000-2018 Simon Kelley
 240 +
 241 +   This program is free software; you can redistribute it and/or modify
 242 +   it under the terms of the GNU General Public License as published by
 243 +   the Free Software Foundation; version 2 dated June, 1991, or
 244 +   (at your option) version 3 dated 29 June, 2007.
 245 +
 246 +   This program is distributed in the hope that it will be useful,
 247 +   but WITHOUT ANY WARRANTY; without even the implied warranty of
 248 +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 249 +   GNU General Public License for more details.
 250 +
 251 +   You should have received a copy of the GNU General Public License
 252 +   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 253 +*/
 254 +
 255 +#include "dnsmasq.h"
 256 +
 257 +#ifdef HAVE_DUMPFILE
 258 +
 259 +static u32 packet_count;
 260 +
 261 +/* https://wiki.wireshark.org/Development/LibpcapFileFormat */
 262 +struct pcap_hdr_s {
 263 +        u32 magic_number;   /* magic number */
 264 +        u16 version_major;  /* major version number */
 265 +        u16 version_minor;  /* minor version number */
 266 +        u32 thiszone;       /* GMT to local correction */
 267 +        u32 sigfigs;        /* accuracy of timestamps */
 268 +        u32 snaplen;        /* max length of captured packets, in octets */
 269 +        u32 network;        /* data link type */
 270 +};
 271 +
 272 +struct pcaprec_hdr_s {
 273 +        u32 ts_sec;         /* timestamp seconds */
 274 +        u32 ts_usec;        /* timestamp microseconds */
 275 +        u32 incl_len;       /* number of octets of packet saved in file */
 276 +        u32 orig_len;       /* actual length of packet */
 277 +};
 278 +
 279 +
 280 +void dump_init(void)
 281 +{
 282 +  struct stat buf;
 283 +  struct pcap_hdr_s header;
 284 +  struct pcaprec_hdr_s pcap_header;
 285 +
 286 +  packet_count = 0;
 287 +
 288 +  if (stat(daemon->dump_file, &buf) == -1)
 289 +    {
 290 +      /* doesn't exist, create and add header */
 291 +      header.magic_number = 0xa1b2c3d4;
 292 +      header.version_major = 2;
 293 +      header.version_minor = 4;
 294 +      header.thiszone = 0;
 295 +      header.sigfigs = 0;
 296 +      header.snaplen = daemon->edns_pktsz + 200; /* slop for IP/UDP headers */
 297 +      header.network = 101; /* DLT_RAW http://www.tcpdump.org/linktypes.html */
 298 +
 299 +      if (errno != ENOENT ||
 300 +         (daemon->dumpfd = creat(daemon->dump_file, S_IRUSR | S_IWUSR)) == -1 ||
 301 +         !read_write(daemon->dumpfd, (void *)&header, sizeof(header), 0))
 302 +       die(_("cannot create %s: %s"), daemon->dump_file, EC_FILE);
 303 +    }
 304 +  else if ((daemon->dumpfd = open(daemon->dump_file, O_APPEND | O_RDWR)) == -1 ||
 305 +          !read_write(daemon->dumpfd, (void *)&header, sizeof(header), 1) ||
 306 +          header.magic_number != 0xa1b2c3d4)
 307 +    die(_("cannot access %s: %s"), daemon->dump_file, EC_FILE);
 308 +  else
 309 +    {
 310 +      /* count existing records */
 311 +      while (read_write(daemon->dumpfd, (void *)&pcap_header, sizeof(pcap_header), 1))
 312 +       {
 313 +         lseek(daemon->dumpfd, pcap_header.incl_len, SEEK_CUR);
 314 +         packet_count++;
 315 +       }
 316 +    }
 317 +}
 318 +
 319 +void dump_packet(int mask, void *packet, size_t len, union mysockaddr *src, union mysockaddr *dst)
 320 +{
 321 +  struct ip ip;
 322 +#ifdef HAVE_IPV6
 323 +  struct ip6_hdr ip6;
 324 +  int family;
 325 +#endif
 326 +  struct udphdr {
 327 +    u16 uh_sport;               /* source port */
 328 +    u16 uh_dport;               /* destination port */
 329 +    u16 uh_ulen;                /* udp length */
 330 +    u16 uh_sum;                 /* udp checksum */
 331 +  } udp;
 332 +  struct pcaprec_hdr_s pcap_header;
 333 +  struct timeval time;
 334 +  u32 i, sum;
 335 +  void *iphdr;
 336 +  size_t ipsz;
 337 +  int rc;
 338 +
 339 +  if (daemon->dumpfd == -1 || !(mask & daemon->dump_mask))
 340 +    return;
 341 +
 342 +  /* So wireshark can Id the packet. */
 343 +  udp.uh_sport = udp.uh_dport = htons(NAMESERVER_PORT);
 344 +
 345 +#ifdef HAVE_IPV6
 346 +  if (src)
 347 +    family = src->sa.sa_family;
 348 +  else
 349 +    family = dst->sa.sa_family;
 350 +
 351 +  if (family == AF_INET6)
 352 +    {
 353 +      iphdr = &ip6;
 354 +      ipsz = sizeof(ip6);
 355 +      memset(&ip6, 0, sizeof(ip6));
 356 +
 357 +      ip6.ip6_vfc = 6 << 4;
 358 +      ip6.ip6_plen = htons(sizeof(struct udphdr) + len);
 359 +      ip6.ip6_nxt = IPPROTO_UDP;
 360 +      ip6.ip6_hops = 64;
 361 +
 362 +      if (src)
 363 +       {
 364 +         memcpy(&ip6.ip6_src, &src->in6.sin6_addr, IN6ADDRSZ);
 365 +         udp.uh_sport = src->in6.sin6_port;
 366 +       }
 367 +
 368 +      if (dst)
 369 +       {
 370 +         memcpy(&ip6.ip6_dst, &dst->in6.sin6_addr, IN6ADDRSZ);
 371 +         udp.uh_dport = dst->in6.sin6_port;
 372 +       }
 373 +
 374 +      /* start UDP checksum */
 375 +      for (sum = 0, i = 0; i < IN6ADDRSZ; i++)
 376 +       sum += ((u16 *)&ip6.ip6_src)[i];
 377 +    }
 378 +  else
 379 +#endif
 380 +    {
 381 +      iphdr = &ip;
 382 +      ipsz = sizeof(ip);
 383 +      memset(&ip, 0, sizeof(ip));
 384 +
 385 +      ip.ip_v = IPVERSION;
 386 +      ip.ip_hl = sizeof(struct ip) / 4;
 387 +      ip.ip_len = htons(sizeof(struct ip) + sizeof(struct udphdr) + len);
 388 +      ip.ip_ttl = IPDEFTTL;
 389 +      ip.ip_p = IPPROTO_UDP;
 390 +
 391 +      if (src)
 392 +       {
 393 +         ip.ip_src = src->in.sin_addr;
 394 +         udp.uh_sport = src->in.sin_port;
 395 +       }
 396 +
 397 +      if (dst)
 398 +       {
 399 +         ip.ip_dst = dst->in.sin_addr;
 400 +         udp.uh_dport = dst->in.sin_port;
 401 +       }
 402 +
 403 +      ip.ip_sum = 0;
 404 +      for (sum = 0, i = 0; i < sizeof(struct ip) / 2; i++)
 405 +       sum += ((u16 *)&ip)[i];
 406 +      while (sum >> 16)
 407 +       sum = (sum & 0xffff) + (sum >> 16);
 408 +      ip.ip_sum = (sum == 0xffff) ? sum : ~sum;
 409 +
 410 +      /* start UDP checksum */
 411 +      sum = ip.ip_src.s_addr & 0xffff;
 412 +      sum += (ip.ip_src.s_addr >> 16) & 0xffff;
 413 +      sum += ip.ip_dst.s_addr & 0xffff;
 414 +      sum += (ip.ip_dst.s_addr >> 16) & 0xffff;
 415 +    }
 416 +
 417 +  if (len & 1)
 418 +    ((unsigned char *)packet)[len] = 0; /* for checksum, in case length is odd. */
 419 +
 420 +  udp.uh_sum = 0;
 421 +  udp.uh_ulen = htons(sizeof(struct udphdr) + len);
 422 +  sum += htons(IPPROTO_UDP);
 423 +  sum += htons(sizeof(struct udphdr) + len);
 424 +  for (i = 0; i < sizeof(struct udphdr)/2; i++)
 425 +    sum += ((u16 *)&udp)[i];
 426 +  for (i = 0; i < (len + 1) / 2; i++)
 427 +    sum += ((u16 *)packet)[i];
 428 +  while (sum >> 16)
 429 +    sum = (sum & 0xffff) + (sum >> 16);
 430 +  udp.uh_sum = (sum == 0xffff) ? sum : ~sum;
 431 +
 432 +  rc = gettimeofday(&time, NULL);
 433 +  pcap_header.ts_sec = time.tv_sec;
 434 +  pcap_header.ts_usec = time.tv_usec;
 435 +  pcap_header.incl_len = pcap_header.orig_len = ipsz + sizeof(udp) + len;
 436 +
 437 +  if (rc == -1 ||
 438 +      !read_write(daemon->dumpfd, (void *)&pcap_header, sizeof(pcap_header), 0) ||
 439 +      !read_write(daemon->dumpfd, iphdr, ipsz, 0) ||
 440 +      !read_write(daemon->dumpfd, (void *)&udp, sizeof(udp), 0) ||
 441 +      !read_write(daemon->dumpfd, (void *)packet, len, 0))
 442 +    my_syslog(LOG_ERR, _("failed to write packet dump"));
 443 +  else
 444 +    my_syslog(LOG_INFO, _("dumping UDP packet %u mask 0x%04x"), ++packet_count, mask);
 445 +
 446 +}
 447 +
 448 +#endif
 449 --- a/src/forward.c
 450 +++ b/src/forward.c
 451 @@ -508,6 +508,10 @@ static int forward_query(int udpfd, unio
 452
 453               if (errno == 0)
 454                 {
 455 +#ifdef HAVE_DUMPFILE
 456 +                 dump_packet(DUMP_UP_QUERY, (void *)header, plen, NULL, &start->addr);
 457 +#endif
 458 +
 459                   /* Keep info in case we want to re-send this packet */
 460                   daemon->srv_save = start;
 461                   daemon->packet_len = plen;
 462 @@ -769,7 +773,7 @@ void reply_query(int fd, int family, tim
 463  #endif
 464
 465    header = (struct dns_header *)daemon->packet;
 466 -
 467 +
 468    if (n < (int)sizeof(struct dns_header) || !(header->hb3 & HB3_QR))
 469      return;
 470
 471 @@ -796,6 +800,12 @@ void reply_query(int fd, int family, tim
 472    if (!(forward = lookup_frec(ntohs(header->id), hash)))
 473      return;
 474
 475 +#ifdef HAVE_DUMPFILE
 476 +  dump_packet((forward->flags & (FREC_DNSKEY_QUERY | FREC_DS_QUERY)) ? DUMP_SEC_REPLY : DUMP_UP_REPLY,
 477 +             (void *)header, n, &serveraddr, NULL);
 478 +#endif
 479 +
 480 +
 481    /* log_query gets called indirectly all over the place, so
 482       pass these in global variables - sorry. */
 483    daemon->log_display_id = forward->log_id;
 484 @@ -934,6 +944,11 @@ void reply_query(int fd, int family, tim
 485                     status = dnssec_validate_reply(now, header, n, daemon->namebuff, daemon->keyname, &forward->class,
 486                                                    !option_bool(OPT_DNSSEC_IGN_NS) && (server->flags & SERV_DO_DNSSEC),
 487                                                    NULL, NULL);
 488 +#ifdef HAVE_DUMPFILE
 489 +                 if (status == STAT_BOGUS)
 490 +                   dump_packet((forward->flags & (FREC_DNSKEY_QUERY | FREC_DS_QUERY)) ? DUMP_SEC_BOGUS : DUMP_BOGUS,
 491 +                               header, (size_t)n, &serveraddr, NULL);
 492 +#endif
 493                 }
 494
 495               /* Can't validate, as we're missing key data. Put this
 496 @@ -1060,6 +1075,11 @@ void reply_query(int fd, int family, tim
 497                                 setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int));
 498                             }
 499  #endif
 500 +
 501 +#ifdef HAVE_DUMPFILE
 502 +                         dump_packet(DUMP_SEC_QUERY, (void *)header, (size_t)nn, NULL, &server->addr);
 503 +#endif
 504 +
 505                           while (retry_send(sendto(fd, (char *)header, nn, 0,
 506                                                    &server->addr.sa,
 507                                                    sa_len(&server->addr))));
 508 @@ -1114,8 +1134,8 @@ void reply_query(int fd, int family, tim
 509               bogusanswer = 1;
 510             }
 511         }
 512 -#endif
 513 -
 514 +#endif
 515 +
 516        /* restore CD bit to the value in the query */
 517        if (forward->flags & FREC_CHECKING_DISABLED)
 518         header->hb4 |= HB4_CD;
 519 @@ -1141,6 +1161,11 @@ void reply_query(int fd, int family, tim
 520               nn = resize_packet(header, nn, NULL, 0);
 521             }
 522  #endif
 523 +
 524 +#ifdef HAVE_DUMPFILE
 525 +         dump_packet(DUMP_REPLY, daemon->packet, (size_t)nn, NULL, &forward->source);
 526 +#endif
 527 +
 528           send_from(forward->fd, option_bool(OPT_NOWILD) || option_bool (OPT_CLEVERBIND), daemon->packet, nn,
 529                     &forward->source, &forward->dest, forward->iface);
 530         }
 531 @@ -1394,7 +1419,11 @@ void receive_query(struct listener *list
 532       pass these in global variables - sorry. */
 533    daemon->log_display_id = ++daemon->log_id;
 534    daemon->log_source_addr = &source_addr;
 535 -
 536 +
 537 +#ifdef HAVE_DUMPFILE
 538 +  dump_packet(DUMP_QUERY, daemon->packet, (size_t)n, &source_addr, NULL);
 539 +#endif
 540 +
 541    if (extract_request(header, (size_t)n, daemon->namebuff, &type))
 542      {
 543  #ifdef HAVE_AUTH
 544 --- a/src/option.c
 545 +++ b/src/option.c
 546 @@ -161,6 +161,8 @@ struct myoption {
 547  #define LOPT_TFTP_MTU      349
 548  #define LOPT_REPLY_DELAY   350
 549  #define LOPT_RAPID_COMMIT  351
 550 +#define LOPT_DUMPFILE      352
 551 +#define LOPT_DUMPMASK      353
 552
 553  #ifdef HAVE_GETOPT_LONG
 554  static const struct option opts[] =
 555 @@ -327,6 +329,8 @@ static const struct myoption opts[] =
 556      { "dhcp-ttl", 1, 0 , LOPT_DHCPTTL },
 557      { "dhcp-reply-delay", 1, 0, LOPT_REPLY_DELAY },
 558      { "dhcp-rapid-commit", 0, 0, LOPT_RAPID_COMMIT },
 559 +    { "dumpfile", 1, 0, LOPT_DUMPFILE },
 560 +    { "dumpmask", 1, 0, LOPT_DUMPMASK },
 561      { NULL, 0, 0, 0 }
 562    };
 563
 564 @@ -500,6 +504,8 @@ static struct {
 565    { LOPT_DHCPTTL, ARG_ONE, "<ttl>", gettext_noop("Set TTL in DNS responses with DHCP-derived addresses."), NULL },
 566    { LOPT_REPLY_DELAY, ARG_ONE, "<integer>", gettext_noop("Delay DHCP replies for at least number of seconds."), NULL },
 567    { LOPT_RAPID_COMMIT, OPT_RAPID_COMMIT, NULL, gettext_noop("Enables DHCPv4 Rapid Commit option."), NULL },
 568 +  { LOPT_DUMPFILE, ARG_ONE, "<path>", gettext_noop("Path to debug packet dump file"), NULL },
 569 +  { LOPT_DUMPMASK, ARG_ONE, "<hex>", gettext_noop("Mask which packets to dump"), NULL },
 570    { 0, 0, NULL, NULL, NULL }
 571  };
 572
 573 @@ -1811,6 +1817,14 @@ static int one_opt(int option, char *arg
 574         ret_err(_("bad MX target"));
 575        break;
 576
 577 +    case LOPT_DUMPFILE:  /* --dumpfile */
 578 +      daemon->dump_file = opt_string_alloc(arg);
 579 +      break;
 580 +
 581 +    case LOPT_DUMPMASK:  /* --dumpmask */
 582 +      daemon->dump_mask = strtol(arg, NULL, 0);
 583 +      break;
 584 +
 585  #ifdef HAVE_DHCP
 586      case 'l':  /* --dhcp-leasefile */
 587        daemon->lease_file = opt_string_alloc(arg);