dnsmasq/src/util.c

/* dnsmasq is Copyright (c) 2000-2009 Simon Kelley

   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; version 2 dated June, 1991, or
   (at your option) version 3 dated 29 June, 2007.

   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, see <http://www.gnu.org/licenses/>.
*/

/* The SURF random number generator was taken from djbdns-1.05, by
   Daniel J Bernstein, which is public domain. */


#include "dnsmasq.h"

#ifdef HAVE_BROKEN_RTC
#include <sys/times.h>
#endif

#ifdef LOCALEDIR
#include <idna.h>
#endif

#ifdef HAVE_ARC4RANDOM
void rand_init(void)
{
  return;
}

unsigned short rand16(void)
{
   return (unsigned short) (arc4random() >> 15);
}

#else

/* SURF random number generator */

typedef unsigned int uint32;

static uint32 seed[32];
static uint32 in[12];
static uint32 out[8];

void rand_init()
{
  int fd = open(RANDFILE, O_RDONLY);

  if (fd == -1 ||
      !read_write(fd, (unsigned char *)&seed, sizeof(seed), 1) ||
      !read_write(fd, (unsigned char *)&in, sizeof(in), 1))
    die(_("failed to seed the random number generator: %s"), NULL, EC_MISC);

  close(fd);
}

#define ROTATE(x,b) (((x) << (b)) | ((x) >> (32 - (b))))
#define MUSH(i,b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x,b));

static void surf(void)
{
  uint32 t[12]; uint32 x; uint32 sum = 0;
  int r; int i; int loop;

  for (i = 0;i < 12;++i) t[i] = in[i] ^ seed[12 + i];
  for (i = 0;i < 8;++i) out[i] = seed[24 + i];
  x = t[11];
  for (loop = 0;loop < 2;++loop) {
    for (r = 0;r < 16;++r) {
      sum += 0x9e3779b9;
      MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13)
      MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13)
      MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13)
    }
    for (i = 0;i < 8;++i) out[i] ^= t[i + 4];
  }
}

unsigned short rand16(void)
{
  static int outleft = 0;

  if (!outleft) {
    if (!++in[0]) if (!++in[1]) if (!++in[2]) ++in[3];
    surf();
    outleft = 8;
  }

  return (unsigned short) out[--outleft];
}

#endif

static int check_name(char *in)
{
  /* remove trailing .
     also fail empty string and label > 63 chars */
  size_t dotgap = 0, l = strlen(in);
  char c;
  int nowhite = 0;

  if (l == 0 || l > MAXDNAME) return 0;

  if (in[l-1] == '.')
    {
      if (l == 1) return 0;
      in[l-1] = 0;
    }

  for (; (c = *in); in++)
    {
      if (c == '.')
	dotgap = 0;
      else if (++dotgap > MAXLABEL)
	return 0;
      else if (isascii(c) && iscntrl(c))
	/* iscntrl only gives expected results for ascii */
	return 0;
#ifndef LOCALEDIR
      else if (!isascii(c))
	return 0;
#endif
      else if (c != ' ')
	nowhite = 1;
    }

  if (!nowhite)
    return 0;

  return 1;
}

/* Hostnames have a more limited valid charset than domain names
   so check for legal char a-z A-Z 0-9 - _
   Note that this may receive a FQDN, so only check the first label
   for the tighter criteria. */
int legal_hostname(char *name)
{
  char c;

  if (!check_name(name))
    return 0;

  for (; (c = *name); name++)
    /* check for legal char a-z A-Z 0-9 - _ . */
    {
      if ((c >= 'A' && c <= 'Z') ||
	  (c >= 'a' && c <= 'z') ||
	  (c >= '0' && c <= '9') ||
	  c == '-' || c == '_')
	continue;

      /* end of hostname part */
      if (c == '.')
	return 1;

      return 0;
    }

  return 1;
}

char *canonicalise(char *in, int *nomem)
{
  char *ret = NULL;
#ifdef LOCALEDIR
  int rc;
#endif

  if (nomem)
    *nomem = 0;

  if (!check_name(in))
    return NULL;

#ifdef LOCALEDIR
  if ((rc = idna_to_ascii_lz(in, &ret, 0)) != IDNA_SUCCESS)
    {
      if (ret)
	free(ret);

      if (nomem && (rc == IDNA_MALLOC_ERROR || rc == IDNA_DLOPEN_ERROR))
	{
	  my_syslog(LOG_ERR, _("failed to allocate memory"));
	  *nomem = 1;
	}

      return NULL;
    }
#else
  if ((ret = whine_malloc(strlen(in)+1)))
    strcpy(ret, in);
  else if (nomem)
    *nomem = 1;
#endif

  return ret;
}

unsigned char *do_rfc1035_name(unsigned char *p, char *sval)
{
  int j;

  while (sval && *sval)
    {
      unsigned char *cp = p++;
      for (j = 0; *sval && (*sval != '.'); sval++, j++)
	*p++ = *sval;
      *cp  = j;
      if (*sval)
	sval++;
    }
  return p;
}

/* for use during startup */
void *safe_malloc(size_t size)
{
  void *ret = malloc(size);

  if (!ret)
    die(_("could not get memory"), NULL, EC_NOMEM);

  return ret;
}

void safe_pipe(int *fd, int read_noblock)
{
  if (pipe(fd) == -1 ||
      !fix_fd(fd[1]) ||
      (read_noblock && !fix_fd(fd[0])))
    die(_("cannot create pipe: %s"), NULL, EC_MISC);
}

void *whine_malloc(size_t size)
{
  void *ret = malloc(size);

  if (!ret)
    my_syslog(LOG_ERR, _("failed to allocate %d bytes"), (int) size);

  return ret;
}

int sockaddr_isequal(union mysockaddr *s1, union mysockaddr *s2)
{
  if (s1->sa.sa_family == s2->sa.sa_family)
    {
      if (s1->sa.sa_family == AF_INET &&
	  s1->in.sin_port == s2->in.sin_port &&
	  s1->in.sin_addr.s_addr == s2->in.sin_addr.s_addr)
	return 1;
#ifdef HAVE_IPV6
      if (s1->sa.sa_family == AF_INET6 &&
	  s1->in6.sin6_port == s2->in6.sin6_port &&
	  IN6_ARE_ADDR_EQUAL(&s1->in6.sin6_addr, &s2->in6.sin6_addr))
	return 1;
#endif
    }
  return 0;
}

int sa_len(union mysockaddr *addr)
{
#ifdef HAVE_SOCKADDR_SA_LEN
  return addr->sa.sa_len;
#else
#ifdef HAVE_IPV6
  if (addr->sa.sa_family == AF_INET6)
    return sizeof(addr->in6);
  else
#endif
    return sizeof(addr->in);
#endif
}

/* don't use strcasecmp and friends here - they may be messed up by LOCALE */
int hostname_isequal(char *a, char *b)
{
  unsigned int c1, c2;

  do {
    c1 = (unsigned char) *a++;
    c2 = (unsigned char) *b++;

    if (c1 >= 'A' && c1 <= 'Z')
      c1 += 'a' - 'A';
    if (c2 >= 'A' && c2 <= 'Z')
      c2 += 'a' - 'A';

    if (c1 != c2)
      return 0;
  } while (c1);

  return 1;
}

time_t dnsmasq_time(void)
{
#ifdef HAVE_BROKEN_RTC
  struct tms dummy;
  static long tps = 0;

  if (tps == 0)
    tps = sysconf(_SC_CLK_TCK);

  return (time_t)(times(&dummy)/tps);
#else
  return time(NULL);
#endif
}

int is_same_net(struct in_addr a, struct in_addr b, struct in_addr mask)
{
  return (a.s_addr & mask.s_addr) == (b.s_addr & mask.s_addr);
}

/* returns port number from address */
int prettyprint_addr(union mysockaddr *addr, char *buf)
{
  int port = 0;

#ifdef HAVE_IPV6
  if (addr->sa.sa_family == AF_INET)
    {
      inet_ntop(AF_INET, &addr->in.sin_addr, buf, ADDRSTRLEN);
      port = ntohs(addr->in.sin_port);
    }
  else if (addr->sa.sa_family == AF_INET6)
    {
      inet_ntop(AF_INET6, &addr->in6.sin6_addr, buf, ADDRSTRLEN);
      port = ntohs(addr->in6.sin6_port);
    }
#else
  strcpy(buf, inet_ntoa(addr->in.sin_addr));
  port = ntohs(addr->in.sin_port);
#endif

  return port;
}

void prettyprint_time(char *buf, unsigned int t)
{
  if (t == 0xffffffff)
    sprintf(buf, _("infinite"));
  else
    {
      unsigned int x, p = 0;
       if ((x = t/86400))
	p += sprintf(&buf[p], "%dd", x);
       if ((x = (t/3600)%24))
	p += sprintf(&buf[p], "%dh", x);
      if ((x = (t/60)%60))
	p += sprintf(&buf[p], "%dm", x);
      if ((x = t%60))
	p += sprintf(&buf[p], "%ds", x);
    }
}


/* in may equal out, when maxlen may be -1 (No max len). */
int parse_hex(char *in, unsigned char *out, int maxlen,
	      unsigned int *wildcard_mask, int *mac_type)
{
  int mask = 0, i = 0;
  char *r;

  if (mac_type)
    *mac_type = 0;

  while (maxlen == -1 || i < maxlen)
    {
      for (r = in; *r != 0 && *r != ':' && *r != '-'; r++);
      if (*r == 0)
	maxlen = i;

      if (r != in )
	{
	  if (*r == '-' && i == 0 && mac_type)
	   {
	      *r = 0;
	      *mac_type = strtol(in, NULL, 16);
	      mac_type = NULL;
	   }
	  else
	    {
	      *r = 0;
	      mask = mask << 1;
	      if (strcmp(in, "*") == 0)
		mask |= 1;
	      else
		out[i] = strtol(in, NULL, 16);
	      i++;
	    }
	}
      in = r+1;
    }

  if (wildcard_mask)
    *wildcard_mask = mask;

  return i;
}

/* return 0 for no match, or (no matched octets) + 1 */
int memcmp_masked(unsigned char *a, unsigned char *b, int len, unsigned int mask)
{
  int i, count;
  for (count = 1, i = len - 1; i >= 0; i--, mask = mask >> 1)
    if (!(mask & 1))
      {
	if (a[i] == b[i])
	  count++;
	else
	  return 0;
      }
  return count;
}

/* _note_ may copy buffer */
int expand_buf(struct iovec *iov, size_t size)
{
  void *new;

  if (size <= (size_t)iov->iov_len)
    return 1;

  if (!(new = whine_malloc(size)))
    {
      errno = ENOMEM;
      return 0;
    }

  if (iov->iov_base)
    {
      memcpy(new, iov->iov_base, iov->iov_len);
      free(iov->iov_base);
    }

  iov->iov_base = new;
  iov->iov_len = size;

  return 1;
}

char *print_mac(char *buff, unsigned char *mac, int len)
{
  char *p = buff;
  int i;

  if (len == 0)
    sprintf(p, "<null>");
  else
    for (i = 0; i < len; i++)
      p += sprintf(p, "%.2x%s", mac[i], (i == len - 1) ? "" : ":");

  return buff;
}

void bump_maxfd(int fd, int *max)
{
  if (fd > *max)
    *max = fd;
}

int retry_send(void)
{
   struct timespec waiter;
   if (errno == EAGAIN)
     {
       waiter.tv_sec = 0;
       waiter.tv_nsec = 10000;
       nanosleep(&waiter, NULL);
       return 1;
     }

   if (errno == EINTR)
     return 1;

   return 0;
}

int read_write(int fd, unsigned char *packet, int size, int rw)
{
  ssize_t n, done;

  for (done = 0; done < size; done += n)
    {
    retry:
      if (rw)
        n = read(fd, &packet[done], (size_t)(size - done));
      else
        n = write(fd, &packet[done], (size_t)(size - done));

      if (n == 0)
        return 0;
      else if (n == -1)
        {
          if (retry_send() || errno == ENOMEM || errno == ENOBUFS)
            goto retry;
          else
            return 0;
        }
    }
  return 1;
}