trimdomain.c

   1 /*-
   2  * Copyright (c) 2001 Brian Somers <brian@Awfulhak.org>
   3  *   Based on original work by Atsushi Murai <amurai@FreeBSD.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  */
  28
  29 #include <sys/cdefs.h>
  30
  31 #include <sys/param.h>
  32
  33 #include <libutil.h>
  34 #include <string.h>
  35 #include <unistd.h>
  36
  37 void trimdomain(char *_fullhost, size_t _hostsize);
  38
  39 static int      isDISP(const char *);
  40
  41 /*-
  42  * Trim the current domain name from fullhost, but only if the result
  43  * is less than or equal to hostsize in length.
  44  *
  45  * This function understands $DISPLAY type fullhosts.
  46  *
  47  * For example:
  48  *
  49  *     trimdomain("abcde.my.domain", 5)       ->   "abcde"
  50  *     trimdomain("abcde.my.domain", 4)       ->   "abcde.my.domain"
  51  *     trimdomain("abcde.my.domain:0.0", 9)   ->   "abcde:0.0"
  52  *     trimdomain("abcde.my.domain:0.0", 8)   ->   "abcde.my.domain:0.0"
  53  */
  54 void
  55 trimdomain(char *fullhost, size_t hostsize)
  56 {
  57         static size_t dlen;
  58         static int first = 1;
  59         static char domain[MAXHOSTNAMELEN];
  60         char *end, *s;
  61         size_t len;
  62
  63         if (first) {
  64                 /* XXX: Should we assume that our domain is this persistent ? */
  65                 first = 0;
  66                 if (gethostname(domain, sizeof(domain) - 1) == 0 &&
  67                     (s = strchr(domain, '.')) != NULL)
  68                         memmove(domain, s + 1, strlen(s + 1) + 1);
  69                 else
  70                         domain[0] = '\0';
  71                 dlen = strlen(domain);
  72         }
  73
  74         if (domain[0] == '\0')
  75                 return;
  76
  77         s = fullhost;
  78         end = (char *)((uintptr_t)s + hostsize + 1);
  79         if ((s = memchr(s, '.', (size_t)(end - s))) != NULL) {
  80                 if (strncasecmp(s + 1, domain, dlen) == 0) {
  81                         if (s[dlen + 1] == '\0') {
  82                                 /* Found -- lose the domain. */
  83                                 *s = '\0';
  84                         } else if (s[dlen + 1] == ':' &&
  85                             isDISP(s + dlen + 2) &&
  86                             (len = strlen(s + dlen + 1)) < (size_t)(end - s)) {
  87                                 /* Found -- shuffle the DISPLAY back. */
  88                                 memmove(s, s + dlen + 1, len + 1);
  89                         }
  90                 }
  91         }
  92 }
  93
  94 /*
  95  * Is the given string NN or NN.NN where ``NN'' is an all-numeric string ?
  96  */
  97 static int
  98 isDISP(const char *disp)
  99 {
 100         size_t w;
 101         int res;
 102
 103         w = strspn(disp, "0123456789");
 104         res = 0;
 105         if (w > 0) {
 106                 if (disp[w] == '\0')
 107                         res = 1;        /* NN */
 108                 else if (disp[w] == '.') {
 109                         disp += w + 1;
 110                         w = strspn(disp, "0123456789");
 111                         if (w > 0 && disp[w] == '\0')
 112                                 res = 1;        /* NN.NN */
 113                 }
 114         }
 115         return (res);
 116 }