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 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 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 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