networking/nslookup.c

   1 /* vi: set sw=4 ts=4: */
   2
   3 //config:config NSLOOKUP
   4 //config:       bool "nslookup (4.5 kb)"
   5 //config:       default y
   6 //config:       help
   7 //config:       nslookup is a tool to query Internet name servers.
   8 //config:
   9 //config:config FEATURE_NSLOOKUP_BIG
  10 //config:       bool "Use internal resolver code instead of libc"
  11 //config:       depends on NSLOOKUP
  12 //config:       default y
  13 //config:
  14 //config:config FEATURE_NSLOOKUP_LONG_OPTIONS
  15 //config:       bool "Enable long options"
  16 //config:       default y
  17 //config:       depends on FEATURE_NSLOOKUP_BIG && LONG_OPTS
  18
  19 //applet:IF_NSLOOKUP(APPLET(nslookup, BB_DIR_USR_BIN, BB_SUID_DROP))
  20
  21 //kbuild:lib-$(CONFIG_NSLOOKUP) += nslookup.o
  22
  23 //usage:#define nslookup_trivial_usage
  24 //usage:       IF_FEATURE_NSLOOKUP_BIG("[-type=QUERY_TYPE] [-debug] ") "HOST [DNS_SERVER]"
  25 //usage:#define nslookup_full_usage "\n\n"
  26 //usage:       "Query DNS about HOST"
  27 //usage:       IF_FEATURE_NSLOOKUP_BIG("\n")
  28 //usage:       IF_FEATURE_NSLOOKUP_BIG("\nQUERY_TYPE: soa,ns,a,"IF_FEATURE_IPV6("aaaa,")"cname,mx,txt,ptr,any")
  29 //usage:#define nslookup_example_usage
  30 //usage:       "$ nslookup localhost\n"
  31 //usage:       "Server:     default\n"
  32 //usage:       "Address:    default\n"
  33 //usage:       "\n"
  34 //usage:       "Name:       debian\n"
  35 //usage:       "Address:    127.0.0.1\n"
  36
  37 #include <resolv.h>
  38 #include <net/if.h>     /* for IFNAMSIZ */
  39 //#include <arpa/inet.h>
  40 //#include <netdb.h>
  41 #include "libbb.h"
  42 #include "common_bufsiz.h"
  43
  44
  45 #if !ENABLE_FEATURE_NSLOOKUP_BIG
  46
  47 /*
  48  * Mini nslookup implementation for busybox
  49  *
  50  * Copyright (C) 1999,2000 by Lineo, inc. and John Beppu
  51  * Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
  52  *
  53  * Correct default name server display and explicit name server option
  54  * added by Ben Zeckel <bzeckel@hmc.edu> June 2001
  55  *
  56  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  57  */
  58
  59 /*
  60  * I'm only implementing non-interactive mode;
  61  * I totally forgot nslookup even had an interactive mode.
  62  *
  63  * This applet is the only user of res_init(). Without it,
  64  * you may avoid pulling in _res global from libc.
  65  */
  66
  67 /* Examples of 'standard' nslookup output
  68  * $ nslookup yahoo.com
  69  * Server:         128.193.0.10
  70  * Address:        128.193.0.10#53
  71  *
  72  * Non-authoritative answer:
  73  * Name:   yahoo.com
  74  * Address: 216.109.112.135
  75  * Name:   yahoo.com
  76  * Address: 66.94.234.13
  77  *
  78  * $ nslookup 204.152.191.37
  79  * Server:         128.193.4.20
  80  * Address:        128.193.4.20#53
  81  *
  82  * Non-authoritative answer:
  83  * 37.191.152.204.in-addr.arpa     canonical name = 37.32-27.191.152.204.in-addr.arpa.
  84  * 37.32-27.191.152.204.in-addr.arpa       name = zeus-pub2.kernel.org.
  85  *
  86  * Authoritative answers can be found from:
  87  * 32-27.191.152.204.in-addr.arpa  nameserver = ns1.kernel.org.
  88  * 32-27.191.152.204.in-addr.arpa  nameserver = ns2.kernel.org.
  89  * 32-27.191.152.204.in-addr.arpa  nameserver = ns3.kernel.org.
  90  * ns1.kernel.org  internet address = 140.211.167.34
  91  * ns2.kernel.org  internet address = 204.152.191.4
  92  * ns3.kernel.org  internet address = 204.152.191.36
  93  */
  94
  95 static int print_host(const char *hostname, const char *header)
  96 {
  97         /* We can't use xhost2sockaddr() - we want to get ALL addresses,
  98          * not just one */
  99         struct addrinfo *result = NULL;
 100         int rc;
 101         struct addrinfo hint;
 102
 103         memset(&hint, 0 , sizeof(hint));
 104         /* hint.ai_family = AF_UNSPEC; - zero anyway */
 105         /* Needed. Or else we will get each address thrice (or more)
 106          * for each possible socket type (tcp,udp,raw...): */
 107         hint.ai_socktype = SOCK_STREAM;
 108         // hint.ai_flags = AI_CANONNAME;
 109         rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result);
 110
 111         if (rc == 0) {
 112                 struct addrinfo *cur = result;
 113                 unsigned cnt = 0;
 114
 115                 printf("%-10s %s\n", header, hostname);
 116                 // puts(cur->ai_canonname); ?
 117                 while (cur) {
 118                         char *dotted, *revhost;
 119                         dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr);
 120                         revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr);
 121
 122                         printf("Address %u: %s%c", ++cnt, dotted, revhost ? ' ' : '\n');
 123                         if (revhost) {
 124                                 puts(revhost);
 125                                 if (ENABLE_FEATURE_CLEAN_UP)
 126                                         free(revhost);
 127                         }
 128                         if (ENABLE_FEATURE_CLEAN_UP)
 129                                 free(dotted);
 130                         cur = cur->ai_next;
 131                 }
 132         } else {
 133 #if ENABLE_VERBOSE_RESOLUTION_ERRORS
 134                 bb_error_msg("can't resolve '%s': %s", hostname, gai_strerror(rc));
 135 #else
 136                 bb_error_msg("can't resolve '%s'", hostname);
 137 #endif
 138         }
 139         if (ENABLE_FEATURE_CLEAN_UP && result)
 140                 freeaddrinfo(result);
 141         return (rc != 0);
 142 }
 143
 144 /* lookup the default nameserver and display it */
 145 static void server_print(void)
 146 {
 147         char *server;
 148         struct sockaddr *sa;
 149
 150 #if ENABLE_FEATURE_IPV6
 151         sa = (struct sockaddr*)_res._u._ext.nsaddrs[0];
 152         if (!sa)
 153 #endif
 154                 sa = (struct sockaddr*)&_res.nsaddr_list[0];
 155         server = xmalloc_sockaddr2dotted_noport(sa);
 156
 157         print_host(server, "Server:");
 158         if (ENABLE_FEATURE_CLEAN_UP)
 159                 free(server);
 160         bb_putchar('\n');
 161 }
 162
 163 /* alter the global _res nameserver structure to use
 164    an explicit dns server instead of what is in /etc/resolv.conf */
 165 static void set_default_dns(const char *server)
 166 {
 167         len_and_sockaddr *lsa;
 168
 169         if (!server)
 170                 return;
 171
 172         /* NB: this works even with, say, "[::1]:5353"! :) */
 173         lsa = xhost2sockaddr(server, 53);
 174
 175         if (lsa->u.sa.sa_family == AF_INET) {
 176                 _res.nscount = 1;
 177                 /* struct copy */
 178                 _res.nsaddr_list[0] = lsa->u.sin;
 179         }
 180 #if ENABLE_FEATURE_IPV6
 181         /* Hoped libc can cope with IPv4 address there too.
 182          * No such luck, glibc 2.4 segfaults even with IPv6,
 183          * maybe I misunderstand how to make glibc use IPv6 addr?
 184          * (uclibc 0.9.31+ should work) */
 185         if (lsa->u.sa.sa_family == AF_INET6) {
 186                 // glibc neither SEGVs nor sends any dgrams with this
 187                 // (strace shows no socket ops):
 188                 //_res.nscount = 0;
 189                 _res._u._ext.nscount = 1;
 190                 /* store a pointer to part of malloc'ed lsa */
 191                 _res._u._ext.nsaddrs[0] = &lsa->u.sin6;
 192                 /* must not free(lsa)! */
 193         }
 194 #endif
 195 }
 196
 197 int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 198 int nslookup_main(int argc, char **argv)
 199 {
 200         /* We allow 1 or 2 arguments.
 201          * The first is the name to be looked up and the second is an
 202          * optional DNS server with which to do the lookup.
 203          * More than 3 arguments is an error to follow the pattern of the
 204          * standard nslookup */
 205         if (!argv[1] || argv[1][0] == '-' || argc > 3)
 206                 bb_show_usage();
 207
 208         /* initialize DNS structure _res used in printing the default
 209          * name server and in the explicit name server option feature. */
 210         res_init();
 211         /* rfc2133 says this enables IPv6 lookups */
 212         /* (but it also says "may be enabled in /etc/resolv.conf") */
 213         /*_res.options |= RES_USE_INET6;*/
 214
 215         set_default_dns(argv[2]);
 216
 217         server_print();
 218
 219         /* getaddrinfo and friends are free to request a resolver
 220          * reinitialization. Just in case, set_default_dns() again
 221          * after getaddrinfo (in server_print). This reportedly helps
 222          * with bug 675 "nslookup does not properly use second argument"
 223          * at least on Debian Wheezy and Openwrt AA (eglibc based).
 224          */
 225         set_default_dns(argv[2]);
 226
 227         return print_host(argv[1], "Name:");
 228 }
 229
 230
 231 #else /****** A version from LEDE / OpenWRT ******/
 232
 233 /*
 234  * musl compatible nslookup
 235  *
 236  * Copyright (C) 2017 Jo-Philipp Wich <jo@mein.io>
 237  *
 238  * Permission to use, copy, modify, and/or distribute this software for any
 239  * purpose with or without fee is hereby granted, provided that the above
 240  * copyright notice and this permission notice appear in all copies.
 241  *
 242  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 243  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 244  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 245  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 246  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 247  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 248  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 249  */
 250
 251 #if 0
 252 # define dbg(...) fprintf(stderr, __VA_ARGS__)
 253 #else
 254 # define dbg(...) ((void)0)
 255 #endif
 256
 257 struct ns {
 258         const char *name;
 259         len_and_sockaddr *lsa;
 260         int failures;
 261         int replies;
 262 };
 263
 264 struct query {
 265         const char *name;
 266         unsigned qlen;
 267 //      unsigned latency;
 268 //      uint8_t rcode;
 269         unsigned char query[512];
 270 //      unsigned char reply[512];
 271 };
 272
 273 static const struct {
 274         unsigned char type;
 275         char name[7];
 276 } qtypes[] = {
 277         { ns_t_soa,   "SOA"   },
 278         { ns_t_ns,    "NS"    },
 279         { ns_t_a,     "A"     },
 280 #if ENABLE_FEATURE_IPV6
 281         { ns_t_aaaa,  "AAAA"  },
 282 #endif
 283         { ns_t_cname, "CNAME" },
 284         { ns_t_mx,    "MX"    },
 285         { ns_t_txt,   "TXT"   },
 286         { ns_t_ptr,   "PTR"   },
 287         { ns_t_any,   "ANY"   },
 288 };
 289
 290 static const char *const rcodes[] = {
 291         "NOERROR",    // 0
 292         "FORMERR",    // 1
 293         "SERVFAIL",   // 2
 294         "NXDOMAIN",   // 3
 295         "NOTIMP",     // 4
 296         "REFUSED",    // 5
 297         "YXDOMAIN",   // 6
 298         "YXRRSET",    // 7
 299         "NXRRSET",    // 8
 300         "NOTAUTH",    // 9
 301         "NOTZONE",    // 10
 302         "11",         // 11 not assigned
 303         "12",         // 12 not assigned
 304         "13",         // 13 not assigned
 305         "14",         // 14 not assigned
 306         "15",         // 15 not assigned
 307 };
 308
 309 #if ENABLE_FEATURE_IPV6
 310 static const char v4_mapped[12] = { 0,0,0,0, 0,0,0,0, 0,0,0xff,0xff };
 311 #endif
 312
 313 struct globals {
 314         unsigned default_port;
 315         unsigned default_retry;
 316         unsigned default_timeout;
 317         unsigned query_count;
 318         unsigned serv_count;
 319         struct ns *server;
 320         struct query *query;
 321         char *search;
 322         smalluint have_search_directive;
 323 } FIX_ALIASING;
 324 #define G (*(struct globals*)bb_common_bufsiz1)
 325 #define INIT_G() do { \
 326         setup_common_bufsiz(); \
 327         G.default_port = 53; \
 328         G.default_retry = 2; \
 329         G.default_timeout = 5; \
 330 } while (0)
 331
 332 enum {
 333         OPT_debug = (1 << 0),
 334 };
 335
 336 static int parse_reply(const unsigned char *msg, size_t len)
 337 {
 338         HEADER *header;
 339
 340         ns_msg handle;
 341         ns_rr rr;
 342         int i, n, rdlen;
 343         const char *format = NULL;
 344         char astr[INET6_ADDRSTRLEN], dname[MAXDNAME];
 345         const unsigned char *cp;
 346
 347         header = (HEADER *)msg;
 348         if (!header->aa)
 349                 printf("Non-authoritative answer:\n");
 350
 351         if (ns_initparse(msg, len, &handle) != 0) {
 352                 //printf("Unable to parse reply: %s\n", strerror(errno));
 353                 return -1;
 354         }
 355
 356         for (i = 0; i < ns_msg_count(handle, ns_s_an); i++) {
 357                 if (ns_parserr(&handle, ns_s_an, i, &rr) != 0) {
 358                         //printf("Unable to parse resource record: %s\n", strerror(errno));
 359                         return -1;
 360                 }
 361
 362                 rdlen = ns_rr_rdlen(rr);
 363
 364                 switch (ns_rr_type(rr))
 365                 {
 366                 case ns_t_a:
 367                         if (rdlen != 4) {
 368                                 dbg("unexpected A record length %d\n", rdlen);
 369                                 return -1;
 370                         }
 371                         inet_ntop(AF_INET, ns_rr_rdata(rr), astr, sizeof(astr));
 372                         printf("Name:\t%s\nAddress: %s\n", ns_rr_name(rr), astr);
 373                         break;
 374
 375 #if ENABLE_FEATURE_IPV6
 376                 case ns_t_aaaa:
 377                         if (rdlen != 16) {
 378                                 dbg("unexpected AAAA record length %d\n", rdlen);
 379                                 return -1;
 380                         }
 381                         inet_ntop(AF_INET6, ns_rr_rdata(rr), astr, sizeof(astr));
 382                         /* bind-utils-9.11.3 uses the same format for A and AAAA answers */
 383                         printf("Name:\t%s\nAddress: %s\n", ns_rr_name(rr), astr);
 384                         break;
 385 #endif
 386
 387                 case ns_t_ns:
 388                         if (!format)
 389                                 format = "%s\tnameserver = %s\n";
 390                         /* fall through */
 391
 392                 case ns_t_cname:
 393                         if (!format)
 394                                 format = "%s\tcanonical name = %s\n";
 395                         /* fall through */
 396
 397                 case ns_t_ptr:
 398                         if (!format)
 399                                 format = "%s\tname = %s\n";
 400                         if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
 401                                         ns_rr_rdata(rr), dname, sizeof(dname)) < 0
 402                         ) {
 403                                 //printf("Unable to uncompress domain: %s\n", strerror(errno));
 404                                 return -1;
 405                         }
 406                         printf(format, ns_rr_name(rr), dname);
 407                         break;
 408
 409                 case ns_t_mx:
 410                         if (rdlen < 2) {
 411                                 printf("MX record too short\n");
 412                                 return -1;
 413                         }
 414                         n = ns_get16(ns_rr_rdata(rr));
 415                         if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
 416                                         ns_rr_rdata(rr) + 2, dname, sizeof(dname)) < 0
 417                         ) {
 418                                 //printf("Cannot uncompress MX domain: %s\n", strerror(errno));
 419                                 return -1;
 420                         }
 421                         printf("%s\tmail exchanger = %d %s\n", ns_rr_name(rr), n, dname);
 422                         break;
 423
 424                 case ns_t_txt:
 425                         if (rdlen < 1) {
 426                                 //printf("TXT record too short\n");
 427                                 return -1;
 428                         }
 429                         n = *(unsigned char *)ns_rr_rdata(rr);
 430                         if (n > 0) {
 431                                 memset(dname, 0, sizeof(dname));
 432                                 memcpy(dname, ns_rr_rdata(rr) + 1, n);
 433                                 printf("%s\ttext = \"%s\"\n", ns_rr_name(rr), dname);
 434                         }
 435                         break;
 436
 437                 case ns_t_soa:
 438                         if (rdlen < 20) {
 439                                 dbg("SOA record too short:%d\n", rdlen);
 440                                 return -1;
 441                         }
 442
 443                         printf("%s\n", ns_rr_name(rr));
 444
 445                         cp = ns_rr_rdata(rr);
 446                         n = ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
 447                                                cp, dname, sizeof(dname));
 448                         if (n < 0) {
 449                                 //printf("Unable to uncompress domain: %s\n", strerror(errno));
 450                                 return -1;
 451                         }
 452
 453                         printf("\torigin = %s\n", dname);
 454                         cp += n;
 455
 456                         n = ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
 457                                                cp, dname, sizeof(dname));
 458                         if (n < 0) {
 459                                 //printf("Unable to uncompress domain: %s\n", strerror(errno));
 460                                 return -1;
 461                         }
 462
 463                         printf("\tmail addr = %s\n", dname);
 464                         cp += n;
 465
 466                         printf("\tserial = %lu\n", ns_get32(cp));
 467                         cp += 4;
 468
 469                         printf("\trefresh = %lu\n", ns_get32(cp));
 470                         cp += 4;
 471
 472                         printf("\tretry = %lu\n", ns_get32(cp));
 473                         cp += 4;
 474
 475                         printf("\texpire = %lu\n", ns_get32(cp));
 476                         cp += 4;
 477
 478                         printf("\tminimum = %lu\n", ns_get32(cp));
 479                         break;
 480
 481                 default:
 482                         break;
 483                 }
 484         }
 485
 486         return i;
 487 }
 488
 489 /*
 490  * Function logic borrowed & modified from musl libc, res_msend.c
 491  * G.query_count is always > 0.
 492  */
 493 static int send_queries(struct ns *ns)
 494 {
 495         unsigned char reply[512];
 496         uint8_t rcode;
 497         len_and_sockaddr *local_lsa;
 498         struct pollfd pfd;
 499         int servfail_retry = 0;
 500         int n_replies = 0;
 501 //      int save_idx = 0;
 502         unsigned retry_interval;
 503         unsigned timeout = G.default_timeout * 1000;
 504         unsigned tstart, tsent, tcur;
 505
 506         pfd.events = POLLIN;
 507         pfd.fd = xsocket_type(&local_lsa, ns->lsa->u.sa.sa_family, SOCK_DGRAM);
 508         /*
 509          * local_lsa has "null" address and port 0 now.
 510          * bind() ensures we have a *particular port* selected by kernel
 511          * and remembered in fd, thus later recv(fd)
 512          * receives only packets sent to this port.
 513          */
 514         xbind(pfd.fd, &local_lsa->u.sa, local_lsa->len);
 515         free(local_lsa);
 516         /* Make read/writes know the destination */
 517         xconnect(pfd.fd, &ns->lsa->u.sa, ns->lsa->len);
 518         ndelay_on(pfd.fd);
 519
 520         retry_interval = timeout / G.default_retry;
 521         tstart = tcur = monotonic_ms();
 522         goto send;
 523
 524         while (tcur - tstart < timeout) {
 525                 int qn;
 526                 int recvlen;
 527
 528                 if (tcur - tsent >= retry_interval) {
 529  send:
 530                         for (qn = 0; qn < G.query_count; qn++) {
 531                                 if (G.query[qn].qlen == 0)
 532                                         continue; /* this one was replied already */
 533
 534                                 if (write(pfd.fd, G.query[qn].query, G.query[qn].qlen) < 0) {
 535                                         bb_perror_msg("write to '%s'", ns->name);
 536                                         n_replies = -1; /* "no go, try next server" */
 537                                         goto ret;
 538                                 }
 539                                 dbg("query %u sent\n", qn);
 540                         }
 541                         tsent = tcur;
 542                         servfail_retry = 2 * G.query_count;
 543                 }
 544
 545                 /* Wait for a response, or until time to retry */
 546                 if (poll(&pfd, 1, retry_interval - (tcur - tsent)) <= 0)
 547                         goto next;
 548
 549                 recvlen = read(pfd.fd, reply, sizeof(reply));
 550                 if (recvlen < 0) {
 551                         bb_perror_msg("read");
 552  next:
 553                         tcur = monotonic_ms();
 554                         continue;
 555                 }
 556
 557                 if (ns->replies++ == 0) {
 558                         printf("Server:\t\t%s\n", ns->name);
 559                         printf("Address:\t%s\n\n",
 560                                 auto_string(xmalloc_sockaddr2dotted(&ns->lsa->u.sa))
 561                         );
 562                         /* In "Address", bind-utils-9.11.3 show port after a hash: "1.2.3.4#53" */
 563                         /* Should we do the same? */
 564                 }
 565
 566                 /* Non-identifiable packet */
 567                 if (recvlen < 4) {
 568                         dbg("read is too short:%d\n", recvlen);
 569                         goto next;
 570                 }
 571
 572                 /* Find which query this answer goes with, if any */
 573 //              qn = save_idx;
 574                 qn = 0;
 575                 for (;;) {
 576                         if (memcmp(reply, G.query[qn].query, 2) == 0) {
 577                                 dbg("response matches query %u\n", qn);
 578                                 break;
 579                         }
 580                         if (++qn >= G.query_count) {
 581                                 dbg("response does not match any query\n");
 582                                 goto next;
 583                         }
 584                 }
 585
 586                 if (G.query[qn].qlen == 0) {
 587                         dbg("dropped duplicate response to query %u\n", qn);
 588                         goto next;
 589                 }
 590
 591                 rcode = reply[3] & 0x0f;
 592                 dbg("query %u rcode:%s\n", qn, rcodes[rcode]);
 593
 594                 /* Retry immediately on SERVFAIL */
 595                 if (rcode == 2) {
 596                         ns->failures++;
 597                         if (servfail_retry) {
 598                                 servfail_retry--;
 599                                 write(pfd.fd, G.query[qn].query, G.query[qn].qlen);
 600                                 dbg("query %u resent\n", qn);
 601                                 goto next;
 602                         }
 603                 }
 604
 605                 /* Process reply */
 606                 G.query[qn].qlen = 0; /* flag: "reply received" */
 607                 tcur = monotonic_ms();
 608 #if 1
 609                 if (option_mask32 & OPT_debug) {
 610                         printf("Query #%d completed in %ums:\n", qn, tcur - tstart);
 611                 }
 612                 if (rcode != 0) {
 613                         printf("** server can't find %s: %s\n",
 614                                         G.query[qn].name, rcodes[rcode]);
 615                 } else {
 616                         if (parse_reply(reply, recvlen) < 0)
 617                                 printf("*** Can't find %s: Parse error\n", G.query[qn].name);
 618                 }
 619                 bb_putchar('\n');
 620                 n_replies++;
 621                 if (n_replies >= G.query_count)
 622                         goto ret;
 623 #else
 624 //used to store replies and process them later
 625                 G.query[qn].latency = tcur - tstart;
 626                 n_replies++;
 627                 if (qn != save_idx) {
 628                         /* "wrong" receive buffer, move to correct one */
 629                         memcpy(G.query[qn].reply, G.query[save_idx].reply, recvlen);
 630                         continue;
 631                 }
 632                 /* G.query[0..save_idx] have replies, move to next one, if exists */
 633                 for (;;) {
 634                         save_idx++;
 635                         if (save_idx >= G.query_count)
 636                                 goto ret; /* all are full: we have all results */
 637                         if (!G.query[save_idx].rlen)
 638                                 break; /* this one is empty */
 639                 }
 640 #endif
 641         } /* while() */
 642
 643  ret:
 644         close(pfd.fd);
 645
 646         return n_replies;
 647 }
 648
 649 static void add_ns(const char *addr)
 650 {
 651         struct ns *ns;
 652         unsigned count;
 653
 654         dbg("%s: addr:'%s'\n", __func__, addr);
 655
 656         count = G.serv_count++;
 657
 658         G.server = xrealloc_vector(G.server, /*8=2^3:*/ 3, count);
 659         ns = &G.server[count];
 660         ns->name = addr;
 661         ns->lsa = xhost2sockaddr(addr, G.default_port);
 662         /*ns->replies = 0; - already is */
 663         /*ns->failures = 0; - already is */
 664 }
 665
 666 static void parse_resolvconf(void)
 667 {
 668         FILE *resolv;
 669
 670         resolv = fopen("/etc/resolv.conf", "r");
 671         if (resolv) {
 672                 char line[512]; /* "search" is defined to be up to 256 chars */
 673
 674                 while (fgets(line, sizeof(line), resolv)) {
 675                         char *p, *arg;
 676
 677                         p = strtok(line, " \t\n");
 678                         if (!p)
 679                                 continue;
 680                         dbg("resolv_key:'%s'\n", p);
 681                         arg = strtok(NULL, "\n");
 682                         dbg("resolv_arg:'%s'\n", arg);
 683                         if (!arg)
 684                                 continue;
 685
 686                         if (strcmp(p, "domain") == 0) {
 687                                 /* domain DOM */
 688                                 if (!G.have_search_directive)
 689                                         goto set_search;
 690                                 continue;
 691                         }
 692                         if (strcmp(p, "search") == 0) {
 693                                 /* search DOM1 DOM2... */
 694                                 G.have_search_directive = 1;
 695  set_search:
 696                                 free(G.search);
 697                                 G.search = xstrdup(arg);
 698                                 dbg("search='%s'\n", G.search);
 699                                 continue;
 700                         }
 701
 702                         if (strcmp(p, "nameserver") != 0)
 703                                 continue;
 704
 705                         /* nameserver DNS */
 706                         add_ns(xstrdup(arg));
 707                 }
 708
 709                 fclose(resolv);
 710         }
 711
 712         if (!G.search) {
 713                 /* default search domain is domain part of hostname */
 714                 char *h = safe_gethostname();
 715                 char *d = strchr(h, '.');
 716                 if (d) {
 717                         G.search = d + 1;
 718                         dbg("search='%s' (from hostname)\n", G.search);
 719                 }
 720                 /* else free(h); */
 721         }
 722
 723         /* Cater for case of "domain ." in resolv.conf */
 724         if (G.search && LONE_CHAR(G.search, '.'))
 725                 G.search = NULL;
 726 }
 727
 728 static void add_query(int type, const char *dname)
 729 {
 730         struct query *new_q;
 731         unsigned count;
 732         ssize_t qlen;
 733
 734         count = G.query_count++;
 735
 736         G.query = xrealloc_vector(G.query, /*4=2^2:*/ 2, count);
 737         new_q = &G.query[count];
 738
 739         dbg("new query#%u type %u for '%s'\n", count, type, dname);
 740         new_q->name = dname;
 741
 742         qlen = res_mkquery(QUERY, dname, C_IN, type,
 743                         /*data:*/ NULL, /*datalen:*/ 0,
 744                         /*newrr:*/ NULL,
 745                         new_q->query, sizeof(new_q->query)
 746         );
 747         new_q->qlen = qlen;
 748 }
 749
 750 static void add_query_with_search(int type, const char *dname)
 751 {
 752         char *s;
 753
 754         if (type == T_PTR || !G.search || strchr(dname, '.')) {
 755                 add_query(type, dname);
 756                 return;
 757         }
 758
 759         s = G.search;
 760         for (;;) {
 761                 char *fullname, *e;
 762
 763                 e = skip_non_whitespace(s);
 764                 fullname = xasprintf("%s.%.*s", dname, (int)(e - s), s);
 765                 add_query(type, fullname);
 766                 s = skip_whitespace(e);
 767                 if (!*s)
 768                         break;
 769         }
 770 }
 771
 772 static char *make_ptr(const char *addrstr)
 773 {
 774         unsigned char addr[16];
 775
 776 #if ENABLE_FEATURE_IPV6
 777         if (inet_pton(AF_INET6, addrstr, addr)) {
 778                 if (memcmp(addr, v4_mapped, 12) != 0) {
 779                         int i;
 780                         char resbuf[80];
 781                         char *ptr = resbuf;
 782                         for (i = 0; i < 16; i++) {
 783                                 *ptr++ = 0x20 | bb_hexdigits_upcase[(unsigned char)addr[15 - i] & 0xf];
 784                                 *ptr++ = '.';
 785                                 *ptr++ = 0x20 | bb_hexdigits_upcase[(unsigned char)addr[15 - i] >> 4];
 786                                 *ptr++ = '.';
 787                         }
 788                         strcpy(ptr, "ip6.arpa");
 789                         return xstrdup(resbuf);
 790                 }
 791                 return xasprintf("%u.%u.%u.%u.in-addr.arpa",
 792                                 addr[15], addr[14], addr[13], addr[12]);
 793         }
 794 #endif
 795
 796         if (inet_pton(AF_INET, addrstr, addr)) {
 797                 return xasprintf("%u.%u.%u.%u.in-addr.arpa",
 798                         addr[3], addr[2], addr[1], addr[0]);
 799         }
 800
 801         return NULL;
 802 }
 803
 804 int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 805 int nslookup_main(int argc UNUSED_PARAM, char **argv)
 806 {
 807         unsigned types;
 808         int rc;
 809         int err;
 810
 811         INIT_G();
 812
 813         /* manpage: "Options can also be specified on the command line
 814          * if they precede the arguments and are prefixed with a hyphen."
 815          */
 816         types = 0;
 817         argv++;
 818         for (;;) {
 819                 const char *options =
 820 // bind-utils-9.11.3 accept these:
 821 // class=   cl=
 822 // type=    ty= querytype= query= qu= q=
 823 // domain=  do=
 824 // port=    po=
 825 // timeout= t=
 826 // retry=   ret=
 827 // ndots=
 828 // recurse
 829 // norecurse
 830 // defname
 831 // nodefname
 832 // vc
 833 // novc
 834 // debug
 835 // nodebug
 836 // d2
 837 // nod2
 838 // search
 839 // nosearch
 840 // sil
 841 // fail
 842 // nofail
 843 // ver (prints version and exits)
 844                         "type\0"      /* 0 */
 845                         "querytype\0" /* 1 */
 846                         "port\0"      /* 2 */
 847                         "retry\0"     /* 3 */
 848                         "debug\0"     /* 4 */
 849                         "t\0" /* disambiguate with "type": else -t=2 fails */
 850                         "timeout\0"   /* 6 */
 851                         "";
 852                 int i;
 853                 char *arg;
 854                 char *val;
 855
 856                 if (!*argv)
 857                         bb_show_usage();
 858                 if (argv[0][0] != '-')
 859                         break;
 860
 861                 /* Separate out "=val" part */
 862                 arg = (*argv++) + 1;
 863                 val = strchrnul(arg, '=');
 864                 if (*val)
 865                         *val++ = '\0';
 866
 867                 i = index_in_substrings(options, arg);
 868                 //bb_error_msg("i:%d arg:'%s' val:'%s'", i, arg, val);
 869                 if (i < 0)
 870                         bb_show_usage();
 871
 872                 if (i <= 1) {
 873                         for (i = 0;; i++) {
 874                                 if (i == ARRAY_SIZE(qtypes))
 875                                         bb_error_msg_and_die("invalid query type \"%s\"", val);
 876                                 if (strcasecmp(qtypes[i].name, val) == 0)
 877                                         break;
 878                         }
 879                         types |= (1 << i);
 880                         continue;
 881                 }
 882                 if (i == 2) {
 883                         G.default_port = xatou_range(val, 1, 0xffff);
 884                 }
 885                 if (i == 3) {
 886                         G.default_retry = xatou_range(val, 1, INT_MAX);
 887                 }
 888                 if (i == 4) {
 889                         option_mask32 |= OPT_debug;
 890                 }
 891                 if (i > 4) {
 892                         G.default_timeout = xatou_range(val, 1, INT_MAX / 1000);
 893                 }
 894         }
 895
 896         /* Use given DNS server if present */
 897         if (argv[1]) {
 898                 if (argv[2])
 899                         bb_show_usage();
 900                 add_ns(argv[1]);
 901         } else {
 902                 parse_resolvconf();
 903                 /* Fall back to localhost if we could not find NS in resolv.conf */
 904                 if (G.serv_count == 0)
 905                         add_ns("127.0.0.1");
 906         }
 907
 908         if (types == 0) {
 909                 /* No explicit type given, guess query type.
 910                  * If we can convert the domain argument into a ptr (means that
 911                  * inet_pton() could read it) we assume a PTR request, else
 912                  * we issue A+AAAA queries and switch to an output format
 913                  * mimicking the one of the traditional nslookup applet.
 914                  */
 915                 char *ptr;
 916
 917                 ptr = make_ptr(argv[0]);
 918                 if (ptr) {
 919                         add_query(T_PTR, ptr);
 920                 } else {
 921                         add_query_with_search(T_A, argv[0]);
 922 #if ENABLE_FEATURE_IPV6
 923                         add_query_with_search(T_AAAA, argv[0]);
 924 #endif
 925                 }
 926         } else {
 927                 int c;
 928                 for (c = 0; c < ARRAY_SIZE(qtypes); c++) {
 929                         if (types & (1 << c))
 930                                 add_query_with_search(qtypes[c].type, argv[0]);
 931                 }
 932         }
 933
 934         for (rc = 0; rc < G.serv_count;) {
 935                 int c;
 936
 937                 c = send_queries(&G.server[rc]);
 938                 if (c > 0) {
 939                         /* more than zero replies received */
 940 #if 0 /* which version does this? */
 941                         if (option_mask32 & OPT_debug) {
 942                                 printf("Replies:\t%d\n", G.server[rc].replies);
 943                                 printf("Failures:\t%d\n\n", G.server[rc].failures);
 944                         }
 945 #endif
 946                         break;
 947 //FIXME: we "break" even though some queries may still be not answered, and other servers may know them?
 948                 }
 949                 /* c = 0: timed out waiting for replies */
 950                 /* c < 0: error (message already printed) */
 951                 rc++;
 952                 if (rc >= G.serv_count) {
 953 //
 954 // NB: bind-utils-9.11.3 behavior (all to stdout, not stderr):
 955 //
 956 // $ nslookup gmail.com 8.8.8.8
 957 // ;; connection timed out; no servers could be reached
 958 //
 959 // Using TCP mode:
 960 // $ nslookup -vc gmail.com 8.8.8.8; echo EXITCODE:$?
 961 //     <~10 sec>
 962 // ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
 963 //     <~10 sec>
 964 // ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
 965 //     <~10 sec>
 966 // ;; connection timed out; no servers could be reached
 967 // ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
 968 //     <empty line>
 969 // EXITCODE:1
 970 // $ _
 971                         printf(";; connection timed out; no servers could be reached\n\n");
 972                         return EXIT_FAILURE;
 973                 }
 974         }
 975
 976         err = 0;
 977         for (rc = 0; rc < G.query_count; rc++) {
 978                 if (G.query[rc].qlen) {
 979                         printf("*** Can't find %s: No answer\n", G.query[rc].name);
 980                         err = 1;
 981                 }
 982         }
 983         if (err) /* should this affect exicode too? */
 984                 bb_putchar('\n');
 985
 986         if (ENABLE_FEATURE_CLEAN_UP) {
 987                 free(G.server);
 988                 free(G.query);
 989         }
 990
 991         return EXIT_SUCCESS;
 992 }
 993
 994 #endif