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 void freebsd15_trimdomain(char *, int);
38 static 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 */
53 void
trimdomain(char * fullhost,size_t hostsize)54 trimdomain(char *fullhost, size_t 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 /*
77 * Clamp hostsize down if it's out-of-bounds of fullhost, to avoid any
78 * kind of out-of-bounds read in the below memchr().
79 */
80 hostsize = strnlen(fullhost, hostsize);
81
82 s = fullhost;
83 end = s + hostsize + 1;
84 if ((s = memchr(s, '.', (size_t)(end - s))) != NULL) {
85 if (strncasecmp(s + 1, domain, dlen) == 0) {
86 if (s[dlen + 1] == '\0') {
87 /* Found -- lose the domain. */
88 *s = '\0';
89 } else if (s[dlen + 1] == ':' &&
90 isDISP(s + dlen + 2) &&
91 (len = strlen(s + dlen + 1)) < (size_t)(end - s)) {
92 /* Found -- shuffle the DISPLAY back. */
93 memmove(s, s + dlen + 1, len + 1);
94 }
95 }
96 }
97 }
98
99 void
freebsd15_trimdomain(char * fullhost,int hostsize)100 freebsd15_trimdomain(char *fullhost, int hostsize)
101 {
102 /*
103 * Note that we intentionally aren't doing anything here about a
104 * negative `hostsize`, to preserve historical behavior. Functionally,
105 * it would have ended up as a very large size passing to the memchr(3),
106 * thus either appearing to work or reading off the end of the buffer if
107 * `fullhost` is actually malformed.
108 */
109 trimdomain(fullhost, hostsize);
110 }
111
112 __sym_compat(trimdomain, freebsd15_trimdomain, FBSD_1.8);
113
114 /*
115 * Is the given string NN or NN.NN where ``NN'' is an all-numeric string ?
116 */
117 static int
isDISP(const char * disp)118 isDISP(const char *disp)
119 {
120 size_t w;
121 int res;
122
123 w = strspn(disp, "0123456789");
124 res = 0;
125 if (w > 0) {
126 if (disp[w] == '\0')
127 res = 1; /* NN */
128 else if (disp[w] == '.') {
129 disp += w + 1;
130 w = strspn(disp, "0123456789");
131 if (w > 0 && disp[w] == '\0')
132 res = 1; /* NN.NN */
133 }
134 }
135 return (res);
136 }
137