external/ibm-public/postfix/dist/src/util/get_domainname.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      get_domainname 3
   6 /* SUMMARY
   7 /*      network domain name lookup
   8 /* SYNOPSIS
   9 /*      #include <get_domainname.h>
  10 /*
  11 /*      const char *get_domainname()
  12 /* DESCRIPTION
  13 /*      get_domainname() returns the local domain name as obtained
  14 /*      by stripping the hostname component from the result from
  15 /*      get_hostname().  The result is the hostname when get_hostname()
  16 /*      does not return a FQDN form ("foo"), or its result has only two
  17 /*      components ("foo.com").
  18 /* DIAGNOSTICS
  19 /*      Fatal errors: no hostname, invalid hostname.
  20 /* SEE ALSO
  21 /*      get_hostname(3)
  22 /* LICENSE
  23 /* .ad
  24 /* .fi
  25 /*      The Secure Mailer license must be distributed with this software.
  26 /* AUTHOR(S)
  27 /*      Wietse Venema
  28 /*      IBM T.J. Watson Research
  29 /*      P.O. Box 704
  30 /*      Yorktown Heights, NY 10598, USA
  31 /*--*/
  32
  33 /* System library. */
  34
  35 #include <sys_defs.h>
  36 #include <string.h>
  37
  38 /* Utility library. */
  39
  40 #include "mymalloc.h"
  41 #include "get_hostname.h"
  42 #include "get_domainname.h"
  43
  44 /* Local stuff. */
  45
  46 static char *my_domain_name;
  47
  48 /* get_domainname - look up my domain name */
  49
  50 const char *get_domainname(void)
  51 {
  52     const char *host;
  53     const char *dot;
  54
  55     /*
  56      * Use the hostname when it is not a FQDN ("foo"), or when the hostname
  57      * actually is a domain name ("foo.com").
  58      */
  59     if (my_domain_name == 0) {
  60         host = get_hostname();
  61         if ((dot = strchr(host, '.')) == 0 || strchr(dot + 1, '.') == 0) {
  62             my_domain_name = mystrdup(host);
  63         } else {
  64             my_domain_name = mystrdup(dot + 1);
  65         }
  66     }
  67     return (my_domain_name);
  68 }