trimdomain.c revision 74288 
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 * $FreeBSD: head/lib/libutil/trimdomain.c 74288 2001-03-15 08:30:05Z brian $
28 */
29
30#include <sys/param.h>
31
32#include <libutil.h>
33#include <string.h>
34#include <unistd.h>
35
36static int	isDISP(const char *);
37
38/*-
39 * Trim the current domain name from fullhost, but only if the result
40 * is less than or equal to hostsize in length.
41 *
42 * This function understands $DISPLAY type fullhosts.
43 *
44 * For example:
45 *
46 *     trimdomain("abcde.my.domain", 5)       ->   "abcde"
47 *     trimdomain("abcde.my.domain", 4)       ->   "abcde.my.domain"
48 *     trimdomain("abcde.my.domain:0.0", 9)   ->   "abcde:0.0"
49 *     trimdomain("abcde.my.domain:0.0", 8)   ->   "abcde.my.domain:0.0"
50 */
51void
52trimdomain(char *fullhost, int hostsize)
53{
54	static char	domain[MAXHOSTNAMELEN];
55	static int	first = 1;
56	static size_t	dlen;
57	char	       *s, *end;
58	size_t		len;
59
60	if (first) {
61		/* XXX: Should we assume that our domain is this persistent ? */
62		first = 0;
63		if (gethostname(domain, sizeof(domain) - 1) == 0 &&
64		    (s = strchr(domain, '.')) != NULL)
65			memmove(domain, s + 1, strlen(s + 1) + 1);
66		else
67			domain[0] = '\0';
68		dlen = strlen(domain);
69	}
70
71	if (domain[0] == '\0')
72		return;
73
74	s = fullhost;
75	end = s + hostsize + 1;
76	for (; (s = memchr(s, '.', end - s)) != NULL; s++) {
77		if (strncasecmp(s + 1, domain, dlen) == 0) {
78			if (s[dlen + 1] == '\0') {
79				/* Found -- lose the domain. */
80				*s = '\0';
81				break;
82			} else if (s[dlen + 1] == ':' &&
83			    isDISP(s + dlen + 2) &&
84			    (len = strlen(s + dlen + 1)) < end - s) {
85				/* Found -- shuffle the DISPLAY back. */
86				memmove(s, s + dlen + 1, len + 1);
87				break;
88			}
89		}
90	}
91}
92
93/*
94 * Is the given string NN or NN.NN where ``NN'' is an all-numeric string ?
95 */
96static int
97isDISP(const char *disp)
98{
99	int	res, w;
100
101	w = strspn(disp, "0123456789");
102	res = 0;
103	if (w > 0) {
104		if (disp[w] == '\0')
105			res = 1;	/* NN */
106		else if (disp[w] == '.') {
107			disp += w + 1;
108			w = strspn(disp, "0123456789");
109			if (w > 0 && disp[w] == '\0')
110				res = 1;	/* NN.NN */
111		}
112	}
113
114	return (res);
115}
116