pith/osdep/domnames.c

   1 /*
   2  * ========================================================================
   3  * Copyright 2013-2022 Eduardo Chappa
   4  * Copyright 2008 University of Washington
   5  *
   6  * Licensed under the Apache License, Version 2.0 (the "License");
   7  * you may not use this file except in compliance with the License.
   8  * You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * ========================================================================
  13  */
  14
  15 #include <system.h>
  16 #include <general.h>
  17
  18 #include "domnames.h"
  19
  20
  21 /*----------------------------------------------------------------------
  22        Get the current host and domain names
  23
  24     Args: hostname   -- buffer to return the hostname in
  25           hsize      -- size of buffer above
  26           domainname -- buffer to return domain name in
  27           dsize      -- size of buffer above
  28
  29   Result: The system host and domain names are returned. If the full host
  30           name is akbar.cac.washington.edu then the domainname is
  31           cac.washington.edu.
  32
  33 On Internet connected hosts this look up uses /etc/hosts and DNS to
  34 figure all this out. On other less well connected machines some other
  35 file may be read. If there is no notion of a domain name the domain
  36 name may be left blank. On a PC where there really isn't a host name
  37 this should return blank strings. The .pinerc will take care of
  38 configuring the domain names. That is, this should only return the
  39 native system's idea of what the names are if the system has such
  40 a concept.
  41  ----*/
  42 void
  43 getdomainnames(char *hostname, int hsize, char *domainname, int dsize)
  44 {
  45 #if HAVE_NETDB_H
  46     char           *dn, hname[MAX_ADDRESS+1];
  47     struct hostent *he;
  48     char          **alias;
  49     char           *maybe = NULL;
  50
  51     if(gethostname(hname, MAX_ADDRESS))
  52       hname[0] = 0xff;
  53
  54     /* sanity check of hostname string */
  55     for(dn = hname; (*dn > 0x20) && (*dn < 0x7f); ++dn)
  56       ;
  57
  58     if(*dn){            /* if invalid string returned, return "unknown" */
  59       strncpy(domainname, "unknown", dsize-1);
  60       domainname[dsize-1] = '\0';
  61       strncpy(hostname, "unknown", hsize-1);
  62       hostname[hsize-1] = '\0';
  63       return;
  64     }
  65
  66     he = gethostbyname(hname);
  67     hostname[0] = '\0';
  68
  69     if(he == NULL){
  70         strncpy(hostname, hname, hsize-1);
  71         hostname[hsize-1] = '\0';
  72     }
  73     else{
  74         /*
  75          * If no dot in hostname it may be the case that there
  76          * is an alias which is really the fully-qualified
  77          * hostname. This could happen if the administrator has
  78          * (incorrectly) put the unqualified name first in the
  79          * hosts file, for example. The problem with looking for
  80          * an alias with a dot is that now we're guessing, since
  81          * the aliases aren't supposed to be the official hostname.
  82          * We'll compromise and only use an alias if the primary
  83          * name has no dot and exactly one of the aliases has a
  84          * dot.
  85          */
  86         strncpy(hostname, he->h_name, hsize-1);
  87         hostname[hsize-1] = '\0';
  88         if(strchr(hostname, '.') == NULL){              /* no dot in hostname */
  89             for(alias = he->h_aliases; *alias; alias++){
  90                 if(strchr(*alias, '.') != NULL){        /* found one */
  91                     if(maybe){          /* oops, this is the second one */
  92                         maybe = NULL;
  93                         break;
  94                     }
  95                     else
  96                       maybe = *alias;
  97                 }
  98             }
  99
 100             if(maybe){
 101                 strncpy(hostname, maybe, hsize-1);
 102                 hostname[hsize-1] = '\0';
 103             }
 104         }
 105     }
 106
 107     hostname[hsize-1] = '\0';
 108
 109     if((dn = strchr(hostname, '.')) != NULL)
 110       strncpy(domainname, dn+1, dsize-1);
 111     else
 112       strncpy(domainname, hostname, dsize-1);
 113
 114     domainname[dsize-1] = '\0';
 115 #else  /* !HAVE_NETDB_H */
 116     /* should only be _WINDOWS */
 117
 118 #ifdef _WINDOWS
 119     char *p;
 120     extern char *mylocalhost(void);
 121
 122     hostname[0] = domainname[0] = '\0';
 123     if(p = mylocalhost())
 124       snprintf(hostname, hsize, "%s", p);
 125
 126     snprintf(domainname, dsize, "%s",
 127             (hostname[0] && hostname[0] != '[' && (p = strchr(hostname,'.')))
 128               ? p+1 : hostname);
 129 #else /* !_WINDOWS */
 130
 131     char *p, hname[MAX_ADDRESS+1];
 132
 133     hostname[0] = domainname[0] = '\0';
 134     if(gethostname(hname, MAX_ADDRESS) == 0)
 135       snprintf(hostname, hsize, "%s", hname);
 136
 137     snprintf(domainname, dsize, "%s",
 138             (hostname[0] && hostname[0] != '[' && (p = strchr(hostname,'.')))
 139               ? p+1 : hostname);
 140 #endif /* !_WINDOWS */
 141 #endif /* !HAVE_NETDB_H */
 142 }