dist/ntp/libntp/numtohost.c

   1 /*      $NetBSD: numtohost.c,v 1.2 2003/12/04 16:23:37 drochner Exp $   */
   2
   3 /*
   4  * numtohost - convert network number to host name.
   5  */
   6
   7 #include "ntp_fp.h"
   8 #include "ntp_stdlib.h"
   9 #include "lib_strbuf.h"
  10
  11 #define LOOPBACKNET     0x7f000000
  12 #define LOOPBACKHOST    0x7f000001
  13 #define LOOPBACKNETMASK 0xff000000
  14
  15 char *
  16 numtohost(
  17         u_int32 netnum
  18         )
  19 {
  20         char *bp;
  21         struct hostent *hp;
  22
  23         /*
  24          * This is really gross, but saves lots of hanging looking for
  25          * hostnames for the radio clocks.  Don't bother looking up
  26          * addresses on the loopback network except for the loopback
  27          * host itself.
  28          */
  29         if ((((ntohl(netnum) & LOOPBACKNETMASK) == LOOPBACKNET)
  30              && (ntohl(netnum) != LOOPBACKHOST))
  31             || ((hp = gethostbyaddr((char *)&netnum, sizeof netnum, AF_INET))
  32                 == 0))
  33             return numtoa(netnum);
  34
  35         LIB_GETBUF(bp);
  36
  37         bp[LIB_BUFLENGTH-1] = '\0';
  38         (void) strncpy(bp, hp->h_name, LIB_BUFLENGTH-1);
  39         return bp;
  40 }