implement scope flags

[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 <inttypes.h>
#include <stddef.h>
#include <stdbool.h>

#include <sys/types.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <net/if.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;
  }
}

/*
 * addr2text and text2addr
 */

#define ADDRFAM_DEBUG
#ifdef ADDRFAM_DEBUG
static void af_debug_func(const char *fmt, ...) {
  int esave= errno;
  va_list al;
  va_start(al,fmt);
  vfprintf(stderr,fmt,al);
  va_end(al);
  errno= esave;
}
# define af_debug(fmt,...) \
  (af_debug_func("%s: " fmt "\n", __func__, __VA_ARGS__))
#else
# define af_debug(fmt,...) ((void)("" fmt "", __VA_ARGS__))
#endif

static bool addrtext_our_errno(int e) {
  return
    e==EAFNOSUPPORT ||
    e==EINVAL ||
    e==ENOSPC ||
    e==ENOSYS;
}

static bool addrtext_scope_use_ifname(const struct sockaddr *sa) {
  const struct in6_addr *in6= &CSIN6(sa)->sin6_addr;
  return
    IN6_IS_ADDR_LINKLOCAL(in6) ||
    IN6_IS_ADDR_MC_LINKLOCAL(in6);
}

int adns_text2addr(const char *addr, uint16_t port, struct sockaddr *sa,
                   socklen_t *salen /* set if OK or ENOSPC */) {
  int af;
  char copybuf[INET6_ADDRSTRLEN];
  const char *parse=addr;
  const char *scopestr=0;
  socklen_t needlen;
  void *dst;
  uint16_t *portp;

#define INVAL(how) do{                          \
  af_debug("invalid: %s: `%s'", how, addr);     \
  return EINVAL;                                \
}while(0)

#define AFCORE(INETx,SINx,sinx)                 \
    af= AF_##INETx;                             \
    dst = &SINx(sa)->sinx##_addr;               \
    portp = &SINx(sa)->sinx##_port;             \
    needlen= sizeof(*SINx(sa));

  if (!strchr(addr, ':')) { /* INET */

    AFCORE(INET,SIN,sin);

  } else { /* INET6 */

    AFCORE(INET6,SIN6,sin6);

    const char *percent= strchr(addr, '%');
    if (percent) {
      ptrdiff_t lhslen = percent - addr;
      if (lhslen >= INET6_ADDRSTRLEN) INVAL("scoped addr lhs too long");
      memcpy(copybuf, addr, lhslen);
      copybuf[lhslen]= 0;

      parse= copybuf;
      scopestr= percent+1;

      af_debug("will parse scoped addr `%s' %% `%s'", parse, scopestr);
    }

  }

#undef AFCORE

  if (scopestr && (flags & adns_qf_addrlit_scope_forbid))
    INVAL("scoped addr but _scope_forbid");

  if (*salen < needlen) {
    *salen = needlen;
    return ENOSPC;
  }
  *salen = needlen;

  memset(sa, 0, needlen);

  sa->sa_family= af;
  *portp = htons(port);

  int r= inet_pton(af,parse,dst);
  if (!r) INVAL("inet_pton rejected");
  if (r<0) {
    af_debug("inet_pton failed on `%s'", parse);
    return errno;
  }

  if (scopestr) {
    errno=0;
    char *ep;
    unsigned long scope= strtoul(scopestr,&ep,10);
    if (errno==ERANGE) INVAL("numeric scope id too large for unsigned long");
    assert(!errno);
    if (!*ep) {
      if (scope > ~(uint32_t)0)
        INVAL("numeric scope id too large for uint32_t");
    } else { /* !!*ep */
      if (flags & adns_qf_addrlit_scope_numeric)
        INVAL("non-numeric scope but _scope_numeric");
      if (!addrtext_scope_use_ifname(sa)) {
        af_debug("cannot convert non-numeric scope"
                 " in non-link-local addr `%s'", addr);
        return ENOSYS;
      }
      errno= 0;
      scope= if_nametoindex(scopestr);
      if (!scope) {
        /* RFC3493 says "No errors are defined".  It's not clear
         * whether that is supposed to mean if_nametoindex "can't
         * fail" (other than by the supplied name not being that of an
         * interface) which seems unrealistic, or that it conflates
         * all its errors together by failing to set errno, or simply
         * that they didn't bother to document the errors.
         *
         * glibc, FreeBSD and OpenBSD all set errno (to ENXIO when
         * appropriate).  See Debian bug #749349.
         *
         * We attempt to deal with this by clearing errno to start
         * with, and then perhaps mapping the results. */
        af_debug("if_nametoindex rejected scope name (errno=%s)",
                 strerror(errno));
        if (errno==0) {
          return ENXIO;
        } else if (addrtext_our_errno(errno)) {
          /* we use these for other purposes, urgh. */
          perror("adns: adns_text2addr: if_nametoindex"
                 " failed with unexpected error");
          return EIO;
        } else {
          return errno;
        }
      } else { /* ix>0 */
        if (scope > ~(uint32_t)0) {
          fprintf(stderr,"adns: adns_text2addr: if_nametoindex"
                  " returned an interface index >=2^32 which will not fit"
                  " in sockaddr_in6.sin6_scope_id");
          return EIO;
        }
      }
    } /* else; !!*ep */

    SIN6(sa)->sin6_scope_id= scope;
  } /* if (scopestr) */

  return 0;
}

int adns_addr2text(const struct sockaddr *sa,
                   char *addr_buffer, int *addr_buflen,
                   int *port_r) {
  const void *src;
  int port;

  if (*addr_buflen < ADNS_ADDR2TEXT_BUFLEN) {
    *addr_buflen = ADNS_ADDR2TEXT_BUFLEN;
    return ENOSPC;
  }

  switch (sa->sa_family) {
    AF_CASES(af);
    af_inet:  src= &CSIN(sa)->sin_addr;    port= CSIN(sa)->sin_port;    break;
    af_inet6: src= &CSIN6(sa)->sin6_addr;  port= CSIN6(sa)->sin6_port;  break;
    default: return EAFNOSUPPORT;
  }

  const char *ok= inet_ntop(sa->sa_family, src, addr_buffer, *addr_buflen);
  assert(ok);

  if (sa->sa_family == AF_INET6) {
    uint32_t scope = CSIN6(sa)->sin6_scope_id;
    if (scope) {
      if (flags & adns_qf_addrlit_scope_forbid)
        return EINVAL;
      int scopeoffset = strlen(addr_buffer);
      int remain = *addr_buflen - scopeoffset;
      char *scopeptr =  addr_buffer + scopeoffset;
      assert(remain >= IF_NAMESIZE+1/*%*/);
      *scopeptr++= '%'; remain--;
      bool parsedname = 0;
      af_debug("will print scoped addr %s %% %"PRIu32"", addr_buffer, scope);
      if (scope <= UINT_MAX /* so we can pass it to if_indextoname */
          && !(flags & adns_qf_addrlit_scope_numeric)
          && addrtext_scope_use_ifname(sa)) {
        parsedname = if_indextoname(scope, scopeptr);
        if (!parsedname) {
          af_debug("if_indextoname rejected scope (errno=%s)",
                   strerror(errno));
          if (errno==ENXIO) {
            /* fair enough, show it as a number then */
          } else if (addrtext_our_errno(errno)) {
            /* we use these for other purposes, urgh. */
            perror("adns: adns_addr2text: if_indextoname"
                   " failed with unexpected error");
            return EIO;
          } else {
            return errno;
          }
        }
      }
      if (!parsedname) {
        int r = snprintf(scopeptr, remain,
                         "%"PRIu32"", scope);
        assert(r < *addr_buflen - scopeoffset);
      }
      af_debug("printed scoped addr `%s'", addr_buffer);
    }
  }

  if (port_r) *port_r= ntohs(port);
  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;
}