utils.c

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/*
 * Asterisk -- A telephony toolkit for Linux.
 *
 * Utility functions
 *
 * Copyright (C) 2004, Digium
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License
 */

#include <ctype.h>
#include <string.h>
#include <asterisk/lock.h>
#include <asterisk/utils.h>

#if defined(__FreeBSD__)

/* duh? ERANGE value copied from web... */
#define ERANGE 34
#undef gethostbyname

AST_MUTEX_DEFINE_STATIC(__mutex);

int gethostbyname_r (const char *name, struct hostent *ret, char *buf,
         size_t buflen, struct hostent **result, 
         int *h_errnop) 
{
   int hsave;
   struct hostent *ph;
   ast_mutex_lock(&__mutex); /* begin critical area */
   hsave = h_errno;

   ph = gethostbyname(name);
   *h_errnop = h_errno; /* copy h_errno to *h_herrnop */
   if (ph == NULL) {
      *result = NULL;
   } else {
      char **p, **q;
      char *pbuf;
      int nbytes=0;
      int naddr=0, naliases=0;
      /* determine if we have enough space in buf */

      /* count how many addresses */
      for (p = ph->h_addr_list; *p != 0; p++) {
         nbytes += ph->h_length; /* addresses */
         nbytes += sizeof(*p); /* pointers */
         naddr++;
      }
      nbytes += sizeof(*p); /* one more for the terminating NULL */

      /* count how many aliases, and total length of strings */
      for (p = ph->h_aliases; *p != 0; p++) {
         nbytes += (strlen(*p)+1); /* aliases */
         nbytes += sizeof(*p);  /* pointers */
         naliases++;
      }
      nbytes += sizeof(*p); /* one more for the terminating NULL */

      /* here nbytes is the number of bytes required in buffer */
      /* as a terminator must be there, the minimum value is ph->h_length */
      if(nbytes > buflen) {
         *result = NULL;
         ast_mutex_unlock(&__mutex); /* end critical area */
         return ERANGE; /* not enough space in buf!! */
      }

      /* There is enough space. Now we need to do a deep copy! */
      /* Allocation in buffer:
         from [0] to [(naddr-1) * sizeof(*p)]:
         pointers to addresses
         at [naddr * sizeof(*p)]:
         NULL
         from [(naddr+1) * sizeof(*p)] to [(naddr+naliases) * sizeof(*p)] :
         pointers to aliases
         at [(naddr+naliases+1) * sizeof(*p)]:
         NULL
         then naddr addresses (fixed length), and naliases aliases (asciiz).
      */

      *ret = *ph;   /* copy whole structure (not its address!) */

      /* copy addresses */
      q = (char **)buf; /* pointer to pointers area (type: char **) */
      ret->h_addr_list = q; /* update pointer to address list */
      pbuf = buf + ((naddr+naliases+2)*sizeof(*p)); /* skip that area */
      for (p = ph->h_addr_list; *p != 0; p++) {
         memcpy(pbuf, *p, ph->h_length); /* copy address bytes */
         *q++ = pbuf; /* the pointer is the one inside buf... */
         pbuf += ph->h_length; /* advance pbuf */
      }
      *q++ = NULL; /* address list terminator */

      /* copy aliases */
      ret->h_aliases = q; /* update pointer to aliases list */
      for (p = ph->h_aliases; *p != 0; p++) {
         strcpy(pbuf, *p); /* copy alias strings */
         *q++ = pbuf; /* the pointer is the one inside buf... */
         pbuf += strlen(*p); /* advance pbuf */
         *pbuf++ = 0; /* string terminator */
      }
      *q++ = NULL; /* terminator */

      strcpy(pbuf, ph->h_name); /* copy alias strings */
      ret->h_name = pbuf;
      pbuf += strlen(ph->h_name); /* advance pbuf */
      *pbuf++ = 0; /* string terminator */

      *result = ret;  /* and let *result point to structure */

   }
   h_errno = hsave;  /* restore h_errno */
   ast_mutex_unlock(&__mutex); /* end critical area */

   return (*result == NULL); /* return 0 on success, non-zero on error */
}


#endif

struct hostent *ast_gethostbyname(const char *host, struct ast_hostent *hp)
{
   int res;
   int herrno;
   const char *s;
   struct hostent *result = NULL;
   /* Although it is perfectly legitimate to lookup a pure integer, for
      the sake of the sanity of people who like to name their peers as
      integers, we break with tradition and refuse to look up a
      pure integer */
   s = host;
   while(s && *s) {
      if (!isdigit(*s))
         break;
      s++;
   }
   if (!s || !*s)
      return NULL;
   res = gethostbyname_r(host, &hp->hp, hp->buf, sizeof(hp->buf), &result, &herrno);

   if (res || !result || !hp->hp.h_addr_list || !hp->hp.h_addr_list[0])
      return NULL;
   return &hp->hp;
}

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