pith/osdep/domnames.c

   1 #if !defined(lint) && !defined(DOS)
   2 static char rcsid[] = "$Id: domnames.c 1176 2008-09-29 21:16:42Z hubert@u.washington.edu $";
   3 #endif
   4
   5 /*
   6  * ========================================================================
   7  * Copyright 2013-2021 Eduardo Chappa
   8  * Copyright 2008 University of Washington
   9  *
  10  * Licensed under the Apache License, Version 2.0 (the "License");
  11  * you may not use this file except in compliance with the License.
  12  * You may obtain a copy of the License at
  13  *
  14  *     http://www.apache.org/licenses/LICENSE-2.0
  15  *
  16  * ========================================================================
  17  */
  18
  19 #include <system.h>
  20 #include <general.h>
  21
  22 #include "domnames.h"
  23
  24
  25 /*----------------------------------------------------------------------
  26        Get the current host and domain names
  27
  28     Args: hostname   -- buffer to return the hostname in
  29           hsize      -- size of buffer above
  30           domainname -- buffer to return domain name in
  31           dsize      -- size of buffer above
  32
  33   Result: The system host and domain names are returned. If the full host
  34           name is akbar.cac.washington.edu then the domainname is
  35           cac.washington.edu.
  36
  37 On Internet connected hosts this look up uses /etc/hosts and DNS to
  38 figure all this out. On other less well connected machines some other
  39 file may be read. If there is no notion of a domain name the domain
  40 name may be left blank. On a PC where there really isn't a host name
  41 this should return blank strings. The .pinerc will take care of
  42 configuring the domain names. That is, this should only return the
  43 native system's idea of what the names are if the system has such
  44 a concept.
  45  ----*/
  46 void
  47 getdomainnames(char *hostname, int hsize, char *domainname, int dsize)
  48 {
  49 #if HAVE_NETDB_H
  50     char           *dn, hname[MAX_ADDRESS+1];
  51     struct hostent *he;
  52     char          **alias;
  53     char           *maybe = NULL;
  54
  55     if(gethostname(hname, MAX_ADDRESS))
  56       hname[0] = 0xff;
  57
  58     /* sanity check of hostname string */
  59     for(dn = hname; (*dn > 0x20) && (*dn < 0x7f); ++dn)
  60       ;
  61
  62     if(*dn){            /* if invalid string returned, return "unknown" */
  63       strncpy(domainname, "unknown", dsize-1);
  64       domainname[dsize-1] = '\0';
  65       strncpy(hostname, "unknown", hsize-1);
  66       hostname[hsize-1] = '\0';
  67       return;
  68     }
  69
  70     he = gethostbyname(hname);
  71     hostname[0] = '\0';
  72
  73     if(he == NULL){
  74         strncpy(hostname, hname, hsize-1);
  75         hostname[hsize-1] = '\0';
  76     }
  77     else{
  78         /*
  79          * If no dot in hostname it may be the case that there
  80          * is an alias which is really the fully-qualified
  81          * hostname. This could happen if the administrator has
  82          * (incorrectly) put the unqualified name first in the
  83          * hosts file, for example. The problem with looking for
  84          * an alias with a dot is that now we're guessing, since
  85          * the aliases aren't supposed to be the official hostname.
  86          * We'll compromise and only use an alias if the primary
  87          * name has no dot and exactly one of the aliases has a
  88          * dot.
  89          */
  90         strncpy(hostname, he->h_name, hsize-1);
  91         hostname[hsize-1] = '\0';
  92         if(strchr(hostname, '.') == NULL){              /* no dot in hostname */
  93             for(alias = he->h_aliases; *alias; alias++){
  94                 if(strchr(*alias, '.') != NULL){        /* found one */
  95                     if(maybe){          /* oops, this is the second one */
  96                         maybe = NULL;
  97                         break;
  98                     }
  99                     else
 100                       maybe = *alias;
 101                 }
 102             }
 103
 104             if(maybe){
 105                 strncpy(hostname, maybe, hsize-1);
 106                 hostname[hsize-1] = '\0';
 107             }
 108         }
 109     }
 110
 111     hostname[hsize-1] = '\0';
 112
 113     if((dn = strchr(hostname, '.')) != NULL)
 114       strncpy(domainname, dn+1, dsize-1);
 115     else
 116       strncpy(domainname, hostname, dsize-1);
 117
 118     domainname[dsize-1] = '\0';
 119 #else  /* !HAVE_NETDB_H */
 120     /* should only be _WINDOWS */
 121
 122 #ifdef _WINDOWS
 123     char *p;
 124     extern char *mylocalhost(void);
 125
 126     hostname[0] = domainname[0] = '\0';
 127     if(p = mylocalhost())
 128       snprintf(hostname, hsize, "%s", p);
 129
 130     snprintf(domainname, dsize, "%s",
 131             (hostname[0] && hostname[0] != '[' && (p = strchr(hostname,'.')))
 132               ? p+1 : hostname);
 133 #else /* !_WINDOWS */
 134
 135     char *p, hname[MAX_ADDRESS+1];
 136
 137     hostname[0] = domainname[0] = '\0';
 138     if(gethostname(hname, MAX_ADDRESS) == 0)
 139       snprintf(hostname, hsize, "%s", hname);
 140
 141     snprintf(domainname, dsize, "%s",
 142             (hostname[0] && hostname[0] != '[' && (p = strchr(hostname,'.')))
 143               ? p+1 : hostname);
 144 #endif /* !_WINDOWS */
 145 #endif /* !HAVE_NETDB_H */
 146 }