xref: /freebsd/lib/libc/net/linkaddr.c (revision dc36d6f9bb1753f3808552f3afd30eda9a7b206a)
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 #include <sys/types.h>
33 #include <sys/socket.h>
34 #include <net/if.h>
35 #include <net/if_dl.h>
36 #include <string.h>
37 
38 /* States*/
39 #define NAMING	0
40 #define GOTONE	1
41 #define GOTTWO	2
42 #define RESET	3
43 /* Inputs */
44 #define	DIGIT	(4*0)
45 #define	END	(4*1)
46 #define DELIM	(4*2)
47 #define LETTER	(4*3)
48 
49 void
link_addr(const char * addr,struct sockaddr_dl * sdl)50 link_addr(const char *addr, struct sockaddr_dl *sdl)
51 {
52 	char *cp = sdl->sdl_data;
53 	char *cplim = sdl->sdl_len + (char *)sdl;
54 	int byte = 0, state = NAMING, new;
55 
56 	bzero((char *)&sdl->sdl_family, sdl->sdl_len - 1);
57 	sdl->sdl_family = AF_LINK;
58 	do {
59 		state &= ~LETTER;
60 		if ((*addr >= '0') && (*addr <= '9')) {
61 			new = *addr - '0';
62 		} else if ((*addr >= 'a') && (*addr <= 'f')) {
63 			new = *addr - 'a' + 10;
64 		} else if ((*addr >= 'A') && (*addr <= 'F')) {
65 			new = *addr - 'A' + 10;
66 		} else if (*addr == 0) {
67 			state |= END;
68 		} else if (state == NAMING &&
69 			   (((*addr >= 'A') && (*addr <= 'Z')) ||
70 			   ((*addr >= 'a') && (*addr <= 'z'))))
71 			state |= LETTER;
72 		else
73 			state |= DELIM;
74 		addr++;
75 		switch (state /* | INPUT */) {
76 		case NAMING | DIGIT:
77 		case NAMING | LETTER:
78 			*cp++ = addr[-1];
79 			continue;
80 		case NAMING | DELIM:
81 			state = RESET;
82 			sdl->sdl_nlen = cp - sdl->sdl_data;
83 			continue;
84 		case GOTTWO | DIGIT:
85 			*cp++ = byte;
86 			/* FALLTHROUGH */
87 		case RESET | DIGIT:
88 			state = GOTONE;
89 			byte = new;
90 			continue;
91 		case GOTONE | DIGIT:
92 			state = GOTTWO;
93 			byte = new + (byte << 4);
94 			continue;
95 		default: /* | DELIM */
96 			state = RESET;
97 			*cp++ = byte;
98 			byte = 0;
99 			continue;
100 		case GOTONE | END:
101 		case GOTTWO | END:
102 			*cp++ = byte;
103 			/* FALLTHROUGH */
104 		case RESET | END:
105 			break;
106 		}
107 		break;
108 	} while (cp < cplim);
109 	sdl->sdl_alen = cp - LLADDR(sdl);
110 	new = cp - (char *)sdl;
111 	if (new > sizeof(*sdl))
112 		sdl->sdl_len = new;
113 	return;
114 }
115 
116 static const char hexlist[] = "0123456789abcdef";
117 
118 char *
link_ntoa(const struct sockaddr_dl * sdl)119 link_ntoa(const struct sockaddr_dl *sdl)
120 {
121 	static char obuf[64];
122 	_Static_assert(sizeof(obuf) >= IFNAMSIZ + 20, "obuf is too small");
123 	char *out;
124 	const u_char *in, *inlim;
125 	int namelen, i, rem;
126 
127 	namelen = (sdl->sdl_nlen <= IFNAMSIZ) ? sdl->sdl_nlen : IFNAMSIZ;
128 
129 	out = obuf;
130 	rem = sizeof(obuf);
131 	if (namelen > 0) {
132 		bcopy(sdl->sdl_data, out, namelen);
133 		out += namelen;
134 		rem -= namelen;
135 		if (sdl->sdl_alen > 0) {
136 			*out++ = ':';
137 			rem--;
138 		}
139 	}
140 
141 	in = (const u_char *)sdl->sdl_data + sdl->sdl_nlen;
142 	inlim = in + sdl->sdl_alen;
143 
144 	while (in < inlim && rem > 1) {
145 		if (in != (const u_char *)sdl->sdl_data + sdl->sdl_nlen) {
146 			*out++ = '.';
147 			rem--;
148 		}
149 		i = *in++;
150 		if (i > 0xf) {
151 			if (rem < 3)
152 				break;
153 			*out++ = hexlist[i >> 4];
154 			*out++ = hexlist[i & 0xf];
155 			rem -= 2;
156 		} else {
157 			if (rem < 2)
158 				break;
159 			*out++ = hexlist[i];
160 			rem--;
161 		}
162 	}
163 	*out = 0;
164 	return (obuf);
165 }
166