trimdomain.c revision 84225 
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__FBSDID("$FreeBSD: head/lib/libutil/trimdomain.c 84225 2001-09-30 22:35:07Z dillon $");
31
32#include <sys/param.h>
33
34#include <libutil.h>
35#include <string.h>
36#include <unistd.h>
37
38static int	isDISP(const char *);
39
40/*-
41 * Trim the current domain name from fullhost, but only if the result
42 * is less than or equal to hostsize in length.
43 *
44 * This function understands $DISPLAY type fullhosts.
45 *
46 * For example:
47 *
48 *     trimdomain("abcde.my.domain", 5)       ->   "abcde"
49 *     trimdomain("abcde.my.domain", 4)       ->   "abcde.my.domain"
50 *     trimdomain("abcde.my.domain:0.0", 9)   ->   "abcde:0.0"
51 *     trimdomain("abcde.my.domain:0.0", 8)   ->   "abcde.my.domain:0.0"
52 */
53void
54trimdomain(char *fullhost, int hostsize)
55{
56	static size_t dlen;
57	static int first = 1;
58	static char domain[MAXHOSTNAMELEN];
59	char *end, *s;
60	size_t len;
61
62	if (first) {
63		/* XXX: Should we assume that our domain is this persistent ? */
64		first = 0;
65		if (gethostname(domain, sizeof(domain) - 1) == 0 &&
66		    (s = strchr(domain, '.')) != NULL)
67			memmove(domain, s + 1, strlen(s + 1) + 1);
68		else
69			domain[0] = '\0';
70		dlen = strlen(domain);
71	}
72
73	if (domain[0] == '\0')
74		return;
75
76	s = fullhost;
77	end = s + hostsize + 1;
78	for (; (s = memchr(s, '.', end - s)) != NULL; s++) {
79		if (strncasecmp(s + 1, domain, dlen) == 0) {
80			if (s[dlen + 1] == '\0') {
81				/* Found -- lose the domain. */
82				*s = '\0';
83				break;
84			} else if (s[dlen + 1] == ':' &&
85			    isDISP(s + dlen + 2) &&
86			    (len = strlen(s + dlen + 1)) < end - s) {
87				/* Found -- shuffle the DISPLAY back. */
88				memmove(s, s + dlen + 1, len + 1);
89				break;
90			}
91		}
92	}
93}
94
95/*
96 * Is the given string NN or NN.NN where ``NN'' is an all-numeric string ?
97 */
98static int
99isDISP(const char *disp)
100{
101	int res, w;
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}
117