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