Do address-family dispatch with lots of switchy functions.

[adns] / src / addrfam.c

/*
 * addrfam.c
 * - address-family specific code
 */
/*
 *  This file is part of adns, which is
 *    Copyright (C) 1997-2000,2003,2006  Ian Jackson
 *    Copyright (C) 1999-2000,2003,2006  Tony Finch
 *    Copyright (C) 1991 Massachusetts Institute of Technology
 *  (See the file INSTALL for full details.)
 *  
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software Foundation,
 *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 */

#include <stdlib.h>
#include <errno.h>
#include <limits.h>
#include <unistd.h>

#include <sys/types.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "internal.h"

/*
 * General address-family operations.
 */

#define SIN(sa) ((struct sockaddr_in *)(sa))
#define CSIN(sa) ((const struct sockaddr_in *)(sa))

#define SIN6(sa) ((struct sockaddr_in6 *)(sa))
#define CSIN6(sa) ((const struct sockaddr_in6 *)(sa))

/* This gadget (thanks, Richard Kettlewell) makes sure that we handle the
 * same set of address families in each switch. */
#define AF_CASES(pre)							\
  case AF_INET: goto pre##_inet;					\
  case AF_INET6: goto pre##_inet6

static void unknown_af(int af) {
  fprintf(stderr, "ADNS INTERNAL: unknown address family %d\n", af);
  abort();
}

int adns__af_supported_p(int af)
{
  switch (af) {
    AF_CASES(af);
    af_inet: af_inet6: return 1;
    default: return 0;
  }
}

int adns__sockaddr_equal_p(const struct sockaddr *sa,
			   const struct sockaddr *sb)
{
  if (sa->sa_family != sb->sa_family) return 0;
  switch (sa->sa_family) {
    AF_CASES(af);
    af_inet: {
      const struct sockaddr_in *sina = CSIN(sa), *sinb = CSIN(sb);
      return (sina->sin_addr.s_addr == sinb->sin_addr.s_addr &&
	      sina->sin_port == sinb->sin_port);
    }
    af_inet6: {
      /* Don't check the flowlabel.  That's apparently useful for routing
       * performance, but doesn't affect the address in any important
       * respect.
       */
      const struct sockaddr_in6 *sin6a = CSIN6(sa), *sin6b = CSIN6(sb);
      return (memcmp(sin6a->sin6_addr.s6_addr,
		     sin6b->sin6_addr.s6_addr,
		     sizeof(sin6a->sin6_addr.s6_addr)) == 0 &&
	      sin6a->sin6_port == sin6b->sin6_port &&
	      sin6a->sin6_scope_id == sin6b->sin6_scope_id);
    }
    default:
      unknown_af(sa->sa_family);
      return -1;
  }
}

int adns__gen_pton(const char *p, int *af_r, union gen_addr *addr_r)
{
  static const int aflist[] = { AF_INET6, AF_INET };
  int i, rc;

  for (i = 0; i < sizeof(aflist)/sizeof(*aflist); i++) {
    rc = inet_pton(aflist[i], p, addr_r);
    assert(rc >= 0);
    if (rc) { *af_r = aflist[i]; return 1; }
  }
  return 0;
}

int adns__addr_width(int af)
{
  switch (af) {
    AF_CASES(af);
    af_inet: return 32;
    af_inet6: return 128;
    default: unknown_af(af); return -1;
  }
}

void adns__prefix_mask(int af, int len, union gen_addr *mask_r)
{
  switch (af) {
    AF_CASES(af);
    af_inet:
      assert(len <= 32);
      mask_r->v4.s_addr = htonl(!len ? 0 : 0xffffffff << (32 - len));
      break;
    af_inet6: {
      int i = len/8, j = len%8;
      unsigned char *m = mask_r->v6.s6_addr;

      assert(len <= 128);
      memset(m, 0xff, i);
      if (j) m[i++] = (0xff << (8-j)) & 0xff;
      memset(m+i, 0, 16-i);
    } break;
    default:
      unknown_af(af);
      break;
  }
}

int adns__guess_prefix_length(int af, const union gen_addr *addr)
{
  switch (af) {
    AF_CASES(af);
    af_inet: {
      unsigned a = (ntohl(addr->v4.s_addr) >> 24) & 0xff;

      if (a < 128) return 8;
      else if (a < 192) return 16;
      else if (a < 224) return 24;
      else return -1;
    } break;
    af_inet6:
      return 64;
    default:
      unknown_af(af);
      return -1;
  }
}

int adns__addr_match_p(int addraf, const union gen_addr *addr,
		       int netaf, const union gen_addr *base,
		       const union gen_addr *mask)
{
  if (addraf != netaf) return 0;
  switch (addraf) {
    AF_CASES(af);
    af_inet:
      return (addr->v4.s_addr & mask->v4.s_addr) == base->v4.s_addr;
    af_inet6: {
      int i;
      const char *a = addr->v6.s6_addr;
      const char *b = base->v6.s6_addr;
      const char *m = mask->v6.s6_addr;

      for (i = 0; i < 16; i++)
	if ((a[i] & m[i]) != b[i]) return 0;
      return 1;
    } break;
    default:
      unknown_af(addraf);
      return -1;
  }
}

const void *adns__sockaddr_to_inaddr(const struct sockaddr *sa)
{
  switch (sa->sa_family) {
    AF_CASES(af);
    af_inet: return &CSIN(sa)->sin_addr;
    af_inet6: return &CSIN6(sa)->sin6_addr;
    default: unknown_af(sa->sa_family); return 0;
  }
}

/*
 * Reverse-domain parsing and construction.
 */

int adns__make_reverse_domain(const struct sockaddr *sa,
			      const char *zone,
			      char **buf_io, size_t bufsz,
			      char **buf_free_r)
{
  size_t req;
  char *p;
  unsigned c, y;
  unsigned long aa;
  const unsigned char *ap;
  int i, j;

  switch (sa->sa_family) {
    AF_CASES(af);
    af_inet:
      req = 4 * 4;
      if (!zone) zone = "in-addr.arpa";
      break;
    af_inet6:
      req = 2 * 32;
      if (!zone) zone = "ip6.arpa";
      break;
    default:
      return ENOSYS;
  }

  req += strlen(zone) + 1;
  if (req <= bufsz)
    p = *buf_io;
  else {
    p = malloc(req); if (!p) return errno;
    *buf_free_r = p;
  }

  *buf_io = p;
  switch (sa->sa_family) {
    AF_CASES(bf);
    bf_inet:
      aa = ntohl(CSIN(sa)->sin_addr.s_addr);
      for (i = 0; i < 4; i++) {
	p += sprintf(p, "%d", (int)(aa & 0xff));
	*p++ = '.';
	aa >>= 8;
      }
      break;
    bf_inet6:
      ap = CSIN6(sa)->sin6_addr.s6_addr + 16;
      for (i = 0; i < 16; i++) {
	c = *--ap;
	for (j = 0; j < 2; j++) {
	  y = c & 0xf;
	  if (y < 10) *p++ = y + '0';
	  else *p++ = y - 10 + 'a';
	  c >>= 4;
	  *p++ = '.';
	}
      }
      break;
    default:
      unknown_af(sa->sa_family);
  }

  strcpy(p, zone);
  return 0;
}


static int inet_rev_parsecomp(const char *p, size_t n)
{
  int i = 0;
  if (n > 3) return -1;

  while (n--) {
    if ('0' <= *p && *p <= '9') i = 10*i + *p++ - '0';
    else return -1;
  }
  return i;
}

static void inet_rev_mkaddr(union gen_addr *addr, const byte *ipv)
{
  addr->v4.s_addr = htonl((ipv[3]<<24) | (ipv[2]<<16) |
			  (ipv[1]<<8) | (ipv[0]));
}

static int inet6_rev_parsecomp(const char *p, size_t n)
{
  if (n != 1) return -1;
  else if ('0' <= *p && *p <= '9') return *p - '0';
  else if ('a' <= *p && *p <= 'f') return *p - 'a' + 10;
  else if ('A' <= *p && *p <= 'F') return *p - 'a' + 10;
  else return -1;
}

static void inet6_rev_mkaddr(union gen_addr *addr, const byte *ipv)
{
  unsigned char *a = addr->v6.s6_addr;
  int i;

  for (i = 0; i < 16; i++)
    a[i] = (ipv[31-2*i] << 4) | (ipv[30-2*i] << 0);
}

static const struct revparse_domain {
  int af;				/* address family */
  int nrevlab;				/* n of reverse-address labels */
  adns_rrtype rrtype;			/* forward-lookup type */

  int (*rev_parsecomp)(const char *p, size_t n);
  /* parse a single component from a label; return the integer value, or -1
   * if it was unintelligible.
   */

  void (*rev_mkaddr)(union gen_addr *addr, const byte *ipv);
  /* write out the parsed address from a vector of parsed components */

  const char *const tail[3];		/* tail label names */
} revparse_domains[NREVDOMAINS] = {
  { AF_INET, 4, adns_r_a, inet_rev_parsecomp, inet_rev_mkaddr,
    { DNS_INADDR_ARPA, 0 } },
  { AF_INET6, 32, adns_r_aaaa, inet6_rev_parsecomp, inet6_rev_mkaddr,
    { DNS_IP6_ARPA, 0 } },
};

#define REVDOMAIN_MAP(rps, labnum) \
  ((labnum) ? (rps)->map : (1 << NREVDOMAINS) - 1)

int adns__revparse_label(struct revparse_state *rps, int labnum,
			 const char *label, int lablen)
{
  unsigned f = REVDOMAIN_MAP(rps, labnum);
  const struct revparse_domain *rpd;
  const char *tp;
  unsigned d;
  int i, ac;

  for (rpd=revparse_domains, i=0, d=1; i<NREVDOMAINS; rpd++, i++, d <<= 1) {
    if (!(f & d)) continue;
    if (labnum >= rpd->nrevlab) {
      tp = rpd->tail[labnum - rpd->nrevlab];
      if (!tp || strncmp(label, tp, lablen) != 0 || tp[lablen])
	goto mismatch;
    } else {
      ac = rpd->rev_parsecomp(label, lablen);
      if (ac < 0) goto mismatch;
      assert(labnum < sizeof(rps->ipv[i]));
      rps->ipv[i][labnum] = ac;
    }
    continue;

  mismatch:
    f &= ~d;
    if (!f) return -1;
  }

  rps->map = f;
  return 0;
}

int adns__revparse_done(struct revparse_state *rps, int nlabels,
			adns_rrtype *rrtype_r, struct af_addr *addr_r)
{
  unsigned f = REVDOMAIN_MAP(rps, nlabels);
  const struct revparse_domain *rpd;
  unsigned d;
  int i, found = -1;

  for (rpd=revparse_domains, i=0, d=1; i<NREVDOMAINS; rpd++, i++, d <<= 1) {
    if (!(f & d)) continue;
    if (nlabels >= rpd->nrevlab && !rpd->tail[nlabels - rpd->nrevlab])
      { found = i; continue; }
    f &= ~d;
    if (!f) return -1;
  }
  assert(found >= 0); assert(f == (1 << found));

  rpd = &revparse_domains[found];
  *rrtype_r = rpd->rrtype;
  addr_r->af = rpd->af;
  rpd->rev_mkaddr(&addr_r->addr, rps->ipv[found]);
  return 0;
}