xref: /freebsd/lib/libc/net/linkaddr.c (revision a7623790fb345e6dc986dfd31df0ace115e6f2e4)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1990, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)linkaddr.c	8.1 (Berkeley) 6/4/93";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #include <sys/types.h>
39 #include <sys/socket.h>
40 #include <net/if.h>
41 #include <net/if_dl.h>
42 #include <string.h>
43 
44 /* States*/
45 #define NAMING	0
46 #define GOTONE	1
47 #define GOTTWO	2
48 #define RESET	3
49 /* Inputs */
50 #define	DIGIT	(4*0)
51 #define	END	(4*1)
52 #define DELIM	(4*2)
53 #define LETTER	(4*3)
54 
55 void
56 link_addr(const char *addr, struct sockaddr_dl *sdl)
57 {
58 	char *cp = sdl->sdl_data;
59 	char *cplim = sdl->sdl_len + (char *)sdl;
60 	int byte = 0, state = NAMING, new;
61 
62 	bzero((char *)&sdl->sdl_family, sdl->sdl_len - 1);
63 	sdl->sdl_family = AF_LINK;
64 	do {
65 		state &= ~LETTER;
66 		if ((*addr >= '0') && (*addr <= '9')) {
67 			new = *addr - '0';
68 		} else if ((*addr >= 'a') && (*addr <= 'f')) {
69 			new = *addr - 'a' + 10;
70 		} else if ((*addr >= 'A') && (*addr <= 'F')) {
71 			new = *addr - 'A' + 10;
72 		} else if (*addr == 0) {
73 			state |= END;
74 		} else if (state == NAMING &&
75 			   (((*addr >= 'A') && (*addr <= 'Z')) ||
76 			   ((*addr >= 'a') && (*addr <= 'z'))))
77 			state |= LETTER;
78 		else
79 			state |= DELIM;
80 		addr++;
81 		switch (state /* | INPUT */) {
82 		case NAMING | DIGIT:
83 		case NAMING | LETTER:
84 			*cp++ = addr[-1];
85 			continue;
86 		case NAMING | DELIM:
87 			state = RESET;
88 			sdl->sdl_nlen = cp - sdl->sdl_data;
89 			continue;
90 		case GOTTWO | DIGIT:
91 			*cp++ = byte;
92 			/* FALLTHROUGH */
93 		case RESET | DIGIT:
94 			state = GOTONE;
95 			byte = new;
96 			continue;
97 		case GOTONE | DIGIT:
98 			state = GOTTWO;
99 			byte = new + (byte << 4);
100 			continue;
101 		default: /* | DELIM */
102 			state = RESET;
103 			*cp++ = byte;
104 			byte = 0;
105 			continue;
106 		case GOTONE | END:
107 		case GOTTWO | END:
108 			*cp++ = byte;
109 			/* FALLTHROUGH */
110 		case RESET | END:
111 			break;
112 		}
113 		break;
114 	} while (cp < cplim);
115 	sdl->sdl_alen = cp - LLADDR(sdl);
116 	new = cp - (char *)sdl;
117 	if (new > sizeof(*sdl))
118 		sdl->sdl_len = new;
119 	return;
120 }
121 
122 static const char hexlist[] = "0123456789abcdef";
123 
124 char *
125 link_ntoa(const struct sockaddr_dl *sdl)
126 {
127 	static char obuf[64];
128 	_Static_assert(sizeof(obuf) >= IFNAMSIZ + 20, "obuf is too small");
129 	char *out;
130 	const u_char *in, *inlim;
131 	int namelen, i, rem;
132 
133 	namelen = (sdl->sdl_nlen <= IFNAMSIZ) ? sdl->sdl_nlen : IFNAMSIZ;
134 
135 	out = obuf;
136 	rem = sizeof(obuf);
137 	if (namelen > 0) {
138 		bcopy(sdl->sdl_data, out, namelen);
139 		out += namelen;
140 		rem -= namelen;
141 		if (sdl->sdl_alen > 0) {
142 			*out++ = ':';
143 			rem--;
144 		}
145 	}
146 
147 	in = (const u_char *)sdl->sdl_data + sdl->sdl_nlen;
148 	inlim = in + sdl->sdl_alen;
149 
150 	while (in < inlim && rem > 1) {
151 		if (in != (const u_char *)sdl->sdl_data + sdl->sdl_nlen) {
152 			*out++ = '.';
153 			rem--;
154 		}
155 		i = *in++;
156 		if (i > 0xf) {
157 			if (rem < 3)
158 				break;
159 			*out++ = hexlist[i >> 4];
160 			*out++ = hexlist[i & 0xf];
161 			rem -= 2;
162 		} else {
163 			if (rem < 2)
164 				break;
165 			*out++ = hexlist[i];
166 			rem--;
167 		}
168 	}
169 	*out = 0;
170 	return (obuf);
171 }
172