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
37 static 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 */
52 void
trimdomain(char * fullhost,int hostsize)53 trimdomain(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 */
95 static int
isDISP(const char * disp)96 isDISP(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