1 /* $OpenBSD: ethers.c,v 1.27 2019/01/25 00:19:25 millert Exp $ */
2
3 /*
4 * Copyright (c) 1998 Todd C. Miller <millert@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 /*
20 * ethers(3) a la Sun.
21 * Originally Written by Roland McGrath <roland@frob.com> 10/14/93.
22 * Substantially modified by Todd C. Miller <millert@openbsd.org>
23 */
24
25 #include <sys/types.h>
26 #include <sys/socket.h>
27 #include <net/if.h>
28 #include <netinet/in.h>
29 #include <netinet/if_ether.h>
30 #include <paths.h>
31 #include <errno.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <ctype.h>
36 #include <limits.h>
37
38 #ifndef _PATH_ETHERS
39 #define _PATH_ETHERS "/etc/ethers"
40 #endif
41
42 static char * _ether_aton(const char *, struct ether_addr *);
43
44 char *
ether_ntoa(struct ether_addr * e)45 ether_ntoa(struct ether_addr *e)
46 {
47 static char a[] = "xx:xx:xx:xx:xx:xx";
48
49 (void)snprintf(a, sizeof a, "%02x:%02x:%02x:%02x:%02x:%02x",
50 e->ether_addr_octet[0], e->ether_addr_octet[1],
51 e->ether_addr_octet[2], e->ether_addr_octet[3],
52 e->ether_addr_octet[4], e->ether_addr_octet[5]);
53
54 return (a);
55 }
56
57 static char *
_ether_aton(const char * s,struct ether_addr * e)58 _ether_aton(const char *s, struct ether_addr *e)
59 {
60 int i;
61 long l;
62 char *pp;
63
64 while (isspace((unsigned char)*s))
65 s++;
66
67 /* expect 6 hex octets separated by ':' or space/NUL if last octet */
68 for (i = 0; i < 6; i++) {
69 l = strtol(s, &pp, 16);
70 if (pp == s || l > 0xFF || l < 0)
71 return (NULL);
72 if (!(*pp == ':' ||
73 (i == 5 && (isspace((unsigned char)*pp) ||
74 *pp == '\0'))))
75 return (NULL);
76 e->ether_addr_octet[i] = (u_char)l;
77 s = pp + 1;
78 }
79
80 /* return character after the octets ala strtol(3) */
81 return (pp);
82 }
83
84 struct ether_addr *
ether_aton(const char * s)85 ether_aton(const char *s)
86 {
87 static struct ether_addr n;
88
89 return (_ether_aton(s, &n) ? &n : NULL);
90 }
91
92 int
ether_ntohost(char * hostname,struct ether_addr * e)93 ether_ntohost(char *hostname, struct ether_addr *e)
94 {
95 FILE *f;
96 char buf[BUFSIZ+1], *p;
97 size_t len;
98 struct ether_addr try;
99
100 f = fopen(_PATH_ETHERS, "re");
101 if (f == NULL)
102 return (-1);
103 while ((p = fgetln(f, &len)) != NULL) {
104 if (p[len-1] == '\n')
105 len--;
106 if (len > sizeof(buf) - 2)
107 continue;
108 (void)memcpy(buf, p, len);
109 buf[len] = '\n'; /* code assumes newlines later on */
110 buf[len+1] = '\0';
111 /* A + in the file meant try YP, ignore it. */
112 if (!strncmp(buf, "+\n", sizeof(buf)))
113 continue;
114 if (ether_line(buf, &try, hostname) == 0 &&
115 memcmp(&try, e, sizeof(try)) == 0) {
116 (void)fclose(f);
117 return (0);
118 }
119 }
120 (void)fclose(f);
121 errno = ENOENT;
122 return (-1);
123 }
124
125 int
ether_hostton(const char * hostname,struct ether_addr * e)126 ether_hostton(const char *hostname, struct ether_addr *e)
127 {
128 FILE *f;
129 char buf[BUFSIZ+1], *p;
130 char try[HOST_NAME_MAX+1];
131 size_t len;
132
133 f = fopen(_PATH_ETHERS, "re");
134 if (f==NULL)
135 return (-1);
136
137 while ((p = fgetln(f, &len)) != NULL) {
138 if (p[len-1] == '\n')
139 len--;
140 if (len > sizeof(buf) - 2)
141 continue;
142 memcpy(buf, p, len);
143 buf[len] = '\n'; /* code assumes newlines later on */
144 buf[len+1] = '\0';
145 /* A + in the file meant try YP, ignore it. */
146 if (!strncmp(buf, "+\n", sizeof(buf)))
147 continue;
148 if (ether_line(buf, e, try) == 0 && strcmp(hostname, try) == 0) {
149 (void)fclose(f);
150 return (0);
151 }
152 }
153 (void)fclose(f);
154 errno = ENOENT;
155 return (-1);
156 }
157
158 int
ether_line(const char * line,struct ether_addr * e,char * hostname)159 ether_line(const char *line, struct ether_addr *e, char *hostname)
160 {
161 char *p;
162 size_t n;
163
164 /* Parse "xx:xx:xx:xx:xx:xx" */
165 if ((p = _ether_aton(line, e)) == NULL || (*p != ' ' && *p != '\t'))
166 goto bad;
167
168 /* Now get the hostname */
169 while (isspace((unsigned char)*p))
170 p++;
171 if (*p == '\0')
172 goto bad;
173 n = strcspn(p, " \t\n");
174 if (n >= HOST_NAME_MAX+1)
175 goto bad;
176 strlcpy(hostname, p, n + 1);
177 return (0);
178
179 bad:
180 errno = EINVAL;
181 return (-1);
182 }
183 DEF_WEAK(ether_line);
184