mdw@git.distorted.org.uk Git - adns/blob - src/addrfam.c

   1 /*
   2  * addrfam.c
   3  * - address-family specific code
   4  */
   5 /*
   6  *  This file is part of adns, which is
   7  *    Copyright (C) 1997-2000,2003,2006  Ian Jackson
   8  *    Copyright (C) 1999-2000,2003,2006  Tony Finch
   9  *    Copyright (C) 1991 Massachusetts Institute of Technology
  10  *  (See the file INSTALL for full details.)
  11  *
  12  *  This program is free software; you can redistribute it and/or modify
  13  *  it under the terms of the GNU General Public License as published by
  14  *  the Free Software Foundation; either version 2, or (at your option)
  15  *  any later version.
  16  *
  17  *  This program is distributed in the hope that it will be useful,
  18  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  *  GNU General Public License for more details.
  21  *
  22  *  You should have received a copy of the GNU General Public License
  23  *  along with this program; if not, write to the Free Software Foundation,
  24  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 #include <stdlib.h>
  28 #include <errno.h>
  29 #include <limits.h>
  30 #include <unistd.h>
  31 #include <inttypes.h>
  32 #include <stddef.h>
  33
  34 #include <sys/types.h>
  35 #include <netdb.h>
  36 #include <sys/socket.h>
  37 #include <netinet/in.h>
  38 #include <arpa/inet.h>
  39 #include <netinet/in.h>
  40 #include <net/if.h>
  41
  42 #include "internal.h"
  43
  44 /*
  45  * General address-family operations.
  46  */
  47
  48 #define SIN(sa) ((struct sockaddr_in *)(sa))
  49 #define CSIN(sa) ((const struct sockaddr_in *)(sa))
  50
  51 #define SIN6(sa) ((struct sockaddr_in6 *)(sa))
  52 #define CSIN6(sa) ((const struct sockaddr_in6 *)(sa))
  53
  54 /* This gadget (thanks, Richard Kettlewell) makes sure that we handle the
  55  * same set of address families in each switch. */
  56 #define AF_CASES(pre)                                                   \
  57   case AF_INET: goto pre##_inet;                                        \
  58   case AF_INET6: goto pre##_inet6
  59
  60 static void unknown_af(int af) {
  61   fprintf(stderr, "ADNS INTERNAL: unknown address family %d\n", af);
  62   abort();
  63 }
  64
  65 int adns__af_supported_p(int af)
  66 {
  67   switch (af) {
  68     AF_CASES(af);
  69     af_inet: af_inet6: return 1;
  70     default: return 0;
  71   }
  72 }
  73
  74 int adns__sockaddr_equal_p(const struct sockaddr *sa,
  75                            const struct sockaddr *sb)
  76 {
  77   if (sa->sa_family != sb->sa_family) return 0;
  78   switch (sa->sa_family) {
  79     AF_CASES(af);
  80     af_inet: {
  81       const struct sockaddr_in *sina = CSIN(sa), *sinb = CSIN(sb);
  82       return (sina->sin_addr.s_addr == sinb->sin_addr.s_addr &&
  83               sina->sin_port == sinb->sin_port);
  84     }
  85     af_inet6: {
  86       /* Don't check the flowlabel.  That's apparently useful for routing
  87        * performance, but doesn't affect the address in any important
  88        * respect.
  89        */
  90       const struct sockaddr_in6 *sin6a = CSIN6(sa), *sin6b = CSIN6(sb);
  91       return (memcmp(sin6a->sin6_addr.s6_addr,
  92                      sin6b->sin6_addr.s6_addr,
  93                      sizeof(sin6a->sin6_addr.s6_addr)) == 0 &&
  94               sin6a->sin6_port == sin6b->sin6_port &&
  95               sin6a->sin6_scope_id == sin6b->sin6_scope_id);
  96     }
  97     default:
  98       unknown_af(sa->sa_family);
  99       return -1;
 100   }
 101 }
 102
 103 int adns__gen_pton(const char *p, int *af_r, union gen_addr *addr_r)
 104 {
 105   static const int aflist[] = { AF_INET6, AF_INET };
 106   int i, rc;
 107
 108   for (i = 0; i < sizeof(aflist)/sizeof(*aflist); i++) {
 109     rc = inet_pton(aflist[i], p, addr_r);
 110     assert(rc >= 0);
 111     if (rc) { *af_r = aflist[i]; return 1; }
 112   }
 113   return 0;
 114 }
 115
 116 int adns__addr_width(int af)
 117 {
 118   switch (af) {
 119     AF_CASES(af);
 120     af_inet: return 32;
 121     af_inet6: return 128;
 122     default: unknown_af(af); return -1;
 123   }
 124 }
 125
 126 void adns__prefix_mask(int af, int len, union gen_addr *mask_r)
 127 {
 128   switch (af) {
 129     AF_CASES(af);
 130     af_inet:
 131       assert(len <= 32);
 132       mask_r->v4.s_addr = htonl(!len ? 0 : 0xffffffff << (32 - len));
 133       break;
 134     af_inet6: {
 135       int i = len/8, j = len%8;
 136       unsigned char *m = mask_r->v6.s6_addr;
 137
 138       assert(len <= 128);
 139       memset(m, 0xff, i);
 140       if (j) m[i++] = (0xff << (8-j)) & 0xff;
 141       memset(m+i, 0, 16-i);
 142     } break;
 143     default:
 144       unknown_af(af);
 145       break;
 146   }
 147 }
 148
 149 int adns__guess_prefix_length(int af, const union gen_addr *addr)
 150 {
 151   switch (af) {
 152     AF_CASES(af);
 153     af_inet: {
 154       unsigned a = (ntohl(addr->v4.s_addr) >> 24) & 0xff;
 155
 156       if (a < 128) return 8;
 157       else if (a < 192) return 16;
 158       else if (a < 224) return 24;
 159       else return -1;
 160     } break;
 161     af_inet6:
 162       return 64;
 163     default:
 164       unknown_af(af);
 165       return -1;
 166   }
 167 }
 168
 169 int adns__addr_match_p(int addraf, const union gen_addr *addr,
 170                        int netaf, const union gen_addr *base,
 171                        const union gen_addr *mask)
 172 {
 173   if (addraf != netaf) return 0;
 174   switch (addraf) {
 175     AF_CASES(af);
 176     af_inet:
 177       return (addr->v4.s_addr & mask->v4.s_addr) == base->v4.s_addr;
 178     af_inet6: {
 179       int i;
 180       const char *a = addr->v6.s6_addr;
 181       const char *b = base->v6.s6_addr;
 182       const char *m = mask->v6.s6_addr;
 183
 184       for (i = 0; i < 16; i++)
 185         if ((a[i] & m[i]) != b[i]) return 0;
 186       return 1;
 187     } break;
 188     default:
 189       unknown_af(addraf);
 190       return -1;
 191   }
 192 }
 193
 194 const void *adns__sockaddr_to_inaddr(const struct sockaddr *sa)
 195 {
 196   switch (sa->sa_family) {
 197     AF_CASES(af);
 198     af_inet: return &CSIN(sa)->sin_addr;
 199     af_inet6: return &CSIN6(sa)->sin6_addr;
 200     default: unknown_af(sa->sa_family); return 0;
 201   }
 202 }
 203
 204 /*
 205  * addr2text and text2addr
 206  */
 207
 208 #define ADDRFAM_DEBUG
 209 #ifdef ADDRFAM_DEBUG
 210 # define af_debug(fmt,...) \
 211   (fprintf(stderr, "%s: " fmt "\n", __func__, __VA_ARGS__))
 212 #else
 213 # define af_debug(fmt,...) ((void)("" fmt "", __VA_ARGS__))
 214 #endif
 215
 216 int adns_text2addr(const char *addr, uint16_t port, struct sockaddr *sa,
 217                    socklen_t *salen /* set if OK or ENOSPC */) {
 218   int af;
 219   char copybuf[INET6_ADDRSTRLEN];
 220   const char *parse=addr;
 221   const char *scopestr=0;
 222   socklen_t needlen;
 223   void *dst;
 224   uint16_t *portp;
 225
 226 #define INVAL(how) do{                          \
 227   af_debug("invalid: %s: `%s'", how, addr);     \
 228   return EINVAL;                                \
 229 }while(0)
 230
 231 #define AFCORE(INETx,SINx,sinx)                 \
 232     af= AF_##INETx;                             \
 233     dst = &SINx(sa)->sinx##_addr;               \
 234     portp = &SINx(sa)->sinx##_port;             \
 235     needlen= sizeof(*SINx(sa));
 236
 237   if (!strchr(addr, ':')) { /* INET */
 238
 239     AFCORE(INET,SIN,sin);
 240
 241   } else { /* INET6 */
 242
 243     AFCORE(INET6,SIN6,sin6);
 244
 245     const char *percent= strchr(addr, '%');
 246     if (percent) {
 247       ptrdiff_t lhslen = percent - addr;
 248       if (lhslen >= INET6_ADDRSTRLEN) INVAL("scoped addr lhs too long");
 249       memcpy(copybuf, addr, lhslen);
 250       copybuf[lhslen]= 0;
 251
 252       parse= copybuf;
 253       scopestr= percent+1;
 254
 255       af_debug("will parse scoped address `%s' %% `%s'", parse, scopestr);
 256     }
 257
 258   }
 259
 260 #undef AFCORE
 261
 262   if (*salen < needlen) {
 263     *salen = needlen;
 264     return ENOSPC;
 265   }
 266   *salen = needlen;
 267
 268   memset(sa, 0, needlen);
 269
 270   sa->sa_family= af;
 271   *portp = htons(port);
 272
 273   int r= inet_pton(af,parse,dst);
 274   if (!r) INVAL("inet_pton rejected");
 275   if (r<0) {
 276     af_debug("inet_pton failed on `%s'", parse);
 277     return errno;
 278   }
 279
 280   if (scopestr) {
 281     errno=0;
 282     char *ep;
 283     unsigned long scope= strtoul(scopestr,&ep,10);
 284     if (errno==ERANGE) INVAL("numeric scope id too large for unsigned long");
 285     assert(!errno);
 286     if (!*ep) {
 287       if (scope > ~(uint32_t)0)
 288         INVAL("numeric scope id too large for uint32_t");
 289     } else { /* !!*ep */
 290       const struct in6_addr *in6= &SIN6(sa)->sin6_addr;
 291       if (!IN6_IS_ADDR_LINKLOCAL(in6) &&
 292           !IN6_IS_ADDR_MC_LINKLOCAL(in6)) {
 293         af_debug("cannot convert non-numeric scope"
 294                  " in non-link-local addr `%s'", addr);
 295         return ENOSYS;
 296       }
 297       errno= 0;
 298       scope= if_nametoindex(scopestr);
 299       if (!scope) {
 300         /* RFC3493 says "No errors are defined".  It's not clear
 301          * whether that is supposed to mean if_nametoindex "can't
 302          * fail" (other than by the supplied name not being that of an
 303          * interface) which seems unrealistic, or that it conflates
 304          * all its errors together by failing to set errno, or simply
 305          * that they didn't bother to document the errors.
 306          *
 307          * glibc, FreeBSD and OpenBSD all set errno (to ENXIO when
 308          * appropriate).  See Debian bug #749349.
 309          *
 310          * We attempt to deal with this by clearing errno to start
 311          * with, and then perhaps mapping the results. */
 312         af_debug("if_nametoindex rejected scope name (errno=%s)",
 313                  strerror(errno));
 314         if (errno==0) {
 315           return ENXIO;
 316         } else if (errno==EAFNOSUPPORT || errno==EINVAL ||
 317                    errno==ENOSPC || errno==ENOSYS) {
 318           /* we use these for other purposes, urgh. */
 319           perror("adns: adns_text2addr: if_nametoindex"
 320                  " failed with unexpected error");
 321           return EIO;
 322         } else {
 323           return errno;
 324         }
 325       } else { /* ix>0 */
 326         if (scope > ~(uint32_t)0) {
 327           fprintf(stderr,"adns: adns_text2addr: if_nametoindex"
 328                   " returned an interface index >=2^32 which will not fit"
 329                   " in sockaddr_in6.sin6_scope_id");
 330           return EIO;
 331         }
 332       }
 333     } /* else; !!*ep */
 334
 335     SIN6(sa)->sin6_scope_id= scope;
 336   } /* if (scopestr) */
 337
 338   return 0;
 339 }
 340
 341 int adns_addr2text(const struct sockaddr *sa,
 342                    char *addr_buffer, int *addr_buflen,
 343                    int *port_r) {
 344   const void *src;
 345   int port;
 346
 347   if (*addr_buflen < ADNS_ADDR2TEXT_BUFLEN) {
 348     *addr_buflen = ADNS_ADDR2TEXT_BUFLEN;
 349     return ENOSPC;
 350   }
 351
 352   switch (sa->sa_family) {
 353     AF_CASES(af);
 354     af_inet:  src= &CSIN(sa)->sin_addr;    port= CSIN(sa)->sin_port;    break;
 355     af_inet6: src= &CSIN6(sa)->sin6_addr;  port= CSIN6(sa)->sin6_port;  break;
 356     default: return EAFNOSUPPORT;
 357   }
 358
 359   const char *ok= inet_ntop(sa->sa_family, src, addr_buffer, *addr_buflen);
 360   assert(ok);
 361
 362   if (sa->sa_family == AF_INET6) {
 363     uint32_t scope = CSIN6(sa)->sin6_scope_id;
 364     if (scope) {
 365       int scopeoffset = strlen(addr_buffer);
 366       int remain = *addr_buflen - scopeoffset;
 367       int r = snprintf(addr_buffer + scopeoffset, remain,
 368                        "%%%"PRIu32"", scope);
 369       assert(r < *addr_buflen - scopeoffset);
 370       af_debug("printed scoped address `%s'", addr_buffer);
 371     }
 372   }
 373
 374   if (port_r) *port_r= ntohs(port);
 375   return 0;
 376 }
 377
 378 /*
 379  * Reverse-domain parsing and construction.
 380  */
 381
 382 int adns__make_reverse_domain(const struct sockaddr *sa,
 383                               const char *zone,
 384                               char **buf_io, size_t bufsz,
 385                               char **buf_free_r)
 386 {
 387   size_t req;
 388   char *p;
 389   unsigned c, y;
 390   unsigned long aa;
 391   const unsigned char *ap;
 392   int i, j;
 393
 394   switch (sa->sa_family) {
 395     AF_CASES(af);
 396     af_inet:
 397       req = 4 * 4;
 398       if (!zone) zone = "in-addr.arpa";
 399       break;
 400     af_inet6:
 401       req = 2 * 32;
 402       if (!zone) zone = "ip6.arpa";
 403       break;
 404     default:
 405       return ENOSYS;
 406   }
 407
 408   req += strlen(zone) + 1;
 409   if (req <= bufsz)
 410     p = *buf_io;
 411   else {
 412     p = malloc(req); if (!p) return errno;
 413     *buf_free_r = p;
 414   }
 415
 416   *buf_io = p;
 417   switch (sa->sa_family) {
 418     AF_CASES(bf);
 419     bf_inet:
 420       aa = ntohl(CSIN(sa)->sin_addr.s_addr);
 421       for (i = 0; i < 4; i++) {
 422         p += sprintf(p, "%d", (int)(aa & 0xff));
 423         *p++ = '.';
 424         aa >>= 8;
 425       }
 426       break;
 427     bf_inet6:
 428       ap = CSIN6(sa)->sin6_addr.s6_addr + 16;
 429       for (i = 0; i < 16; i++) {
 430         c = *--ap;
 431         for (j = 0; j < 2; j++) {
 432           y = c & 0xf;
 433           if (y < 10) *p++ = y + '0';
 434           else *p++ = y - 10 + 'a';
 435           c >>= 4;
 436           *p++ = '.';
 437         }
 438       }
 439       break;
 440     default:
 441       unknown_af(sa->sa_family);
 442   }
 443
 444   strcpy(p, zone);
 445   return 0;
 446 }
 447
 448
 449 static int inet_rev_parsecomp(const char *p, size_t n)
 450 {
 451   int i = 0;
 452   if (n > 3) return -1;
 453
 454   while (n--) {
 455     if ('0' <= *p && *p <= '9') i = 10*i + *p++ - '0';
 456     else return -1;
 457   }
 458   return i;
 459 }
 460
 461 static void inet_rev_mkaddr(union gen_addr *addr, const byte *ipv)
 462 {
 463   addr->v4.s_addr = htonl((ipv[3]<<24) | (ipv[2]<<16) |
 464                           (ipv[1]<<8) | (ipv[0]));
 465 }
 466
 467 static int inet6_rev_parsecomp(const char *p, size_t n)
 468 {
 469   if (n != 1) return -1;
 470   else if ('0' <= *p && *p <= '9') return *p - '0';
 471   else if ('a' <= *p && *p <= 'f') return *p - 'a' + 10;
 472   else if ('A' <= *p && *p <= 'F') return *p - 'a' + 10;
 473   else return -1;
 474 }
 475
 476 static void inet6_rev_mkaddr(union gen_addr *addr, const byte *ipv)
 477 {
 478   unsigned char *a = addr->v6.s6_addr;
 479   int i;
 480
 481   for (i = 0; i < 16; i++)
 482     a[i] = (ipv[31-2*i] << 4) | (ipv[30-2*i] << 0);
 483 }
 484
 485 static const struct revparse_domain {
 486   int af;                               /* address family */
 487   int nrevlab;                          /* n of reverse-address labels */
 488   adns_rrtype rrtype;                   /* forward-lookup type */
 489
 490   int (*rev_parsecomp)(const char *p, size_t n);
 491   /* parse a single component from a label; return the integer value, or -1
 492    * if it was unintelligible.
 493    */
 494
 495   void (*rev_mkaddr)(union gen_addr *addr, const byte *ipv);
 496   /* write out the parsed address from a vector of parsed components */
 497
 498   const char *const tail[3];            /* tail label names */
 499 } revparse_domains[NREVDOMAINS] = {
 500   { AF_INET, 4, adns_r_a, inet_rev_parsecomp, inet_rev_mkaddr,
 501     { DNS_INADDR_ARPA, 0 } },
 502   { AF_INET6, 32, adns_r_aaaa, inet6_rev_parsecomp, inet6_rev_mkaddr,
 503     { DNS_IP6_ARPA, 0 } },
 504 };
 505
 506 #define REVDOMAIN_MAP(rps, labnum) \
 507   ((labnum) ? (rps)->map : (1 << NREVDOMAINS) - 1)
 508
 509 int adns__revparse_label(struct revparse_state *rps, int labnum,
 510                          const char *label, int lablen)
 511 {
 512   unsigned f = REVDOMAIN_MAP(rps, labnum);
 513   const struct revparse_domain *rpd;
 514   const char *tp;
 515   unsigned d;
 516   int i, ac;
 517
 518   for (rpd=revparse_domains, i=0, d=1; i<NREVDOMAINS; rpd++, i++, d <<= 1) {
 519     if (!(f & d)) continue;
 520     if (labnum >= rpd->nrevlab) {
 521       tp = rpd->tail[labnum - rpd->nrevlab];
 522       if (!tp || strncmp(label, tp, lablen) != 0 || tp[lablen])
 523         goto mismatch;
 524     } else {
 525       ac = rpd->rev_parsecomp(label, lablen);
 526       if (ac < 0) goto mismatch;
 527       assert(labnum < sizeof(rps->ipv[i]));
 528       rps->ipv[i][labnum] = ac;
 529     }
 530     continue;
 531
 532   mismatch:
 533     f &= ~d;
 534     if (!f) return -1;
 535   }
 536
 537   rps->map = f;
 538   return 0;
 539 }
 540
 541 int adns__revparse_done(struct revparse_state *rps, int nlabels,
 542                         adns_rrtype *rrtype_r, struct af_addr *addr_r)
 543 {
 544   unsigned f = REVDOMAIN_MAP(rps, nlabels);
 545   const struct revparse_domain *rpd;
 546   unsigned d;
 547   int i, found = -1;
 548
 549   for (rpd=revparse_domains, i=0, d=1; i<NREVDOMAINS; rpd++, i++, d <<= 1) {
 550     if (!(f & d)) continue;
 551     if (nlabels >= rpd->nrevlab && !rpd->tail[nlabels - rpd->nrevlab])
 552       { found = i; continue; }
 553     f &= ~d;
 554     if (!f) return -1;
 555   }
 556   assert(found >= 0); assert(f == (1 << found));
 557
 558   rpd = &revparse_domains[found];
 559   *rrtype_r = rpd->rrtype;
 560   addr_r->af = rpd->af;
 561   rpd->rev_mkaddr(&addr_r->addr, rps->ipv[found]);
 562   return 0;
 563 }