1/*	$OpenBSD: inet_ntop.c,v 1.8 2008/12/09 19:38:38 otto Exp $	*/
2
3/* Copyright (c) 1996 by Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
10 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
11 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
12 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
13 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
14 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
15 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
16 * SOFTWARE.
17 */
18
19/* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */
20
21#include "includes.h"
22
23#ifndef HAVE_INET_NTOP
24
25#include <sys/param.h>
26#include <sys/types.h>
27#include <sys/socket.h>
28#include <netinet/in.h>
29#include <arpa/inet.h>
30#include <arpa/nameser.h>
31#include <string.h>
32#include <errno.h>
33#include <stdio.h>
34
35#ifndef IN6ADDRSZ
36#define IN6ADDRSZ   16   /* IPv6 T_AAAA */
37#endif
38
39#ifndef INT16SZ
40#define INT16SZ     2    /* for systems without 16-bit ints */
41#endif
42
43/*
44 * WARNING: Don't even consider trying to compile this on a system where
45 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
46 */
47
48static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
49static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
50
51/* char *
52 * inet_ntop(af, src, dst, size)
53 *	convert a network format address to presentation format.
54 * return:
55 *	pointer to presentation format address (`dst'), or NULL (see errno).
56 * author:
57 *	Paul Vixie, 1996.
58 */
59const char *
60inet_ntop(int af, const void *src, char *dst, socklen_t size)
61{
62	switch (af) {
63	case AF_INET:
64		return (inet_ntop4(src, dst, (size_t)size));
65	case AF_INET6:
66		return (inet_ntop6(src, dst, (size_t)size));
67	default:
68		errno = EAFNOSUPPORT;
69		return (NULL);
70	}
71	/* NOTREACHED */
72}
73
74/* const char *
75 * inet_ntop4(src, dst, size)
76 *	format an IPv4 address, more or less like inet_ntoa()
77 * return:
78 *	`dst' (as a const)
79 * notes:
80 *	(1) uses no statics
81 *	(2) takes a u_char* not an in_addr as input
82 * author:
83 *	Paul Vixie, 1996.
84 */
85static const char *
86inet_ntop4(const u_char *src, char *dst, size_t size)
87{
88	static const char fmt[] = "%u.%u.%u.%u";
89	char tmp[sizeof "255.255.255.255"];
90	int l;
91
92	l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
93	if (l <= 0 || l >= size) {
94		errno = ENOSPC;
95		return (NULL);
96	}
97	strlcpy(dst, tmp, size);
98	return (dst);
99}
100
101/* const char *
102 * inet_ntop6(src, dst, size)
103 *	convert IPv6 binary address into presentation (printable) format
104 * author:
105 *	Paul Vixie, 1996.
106 */
107static const char *
108inet_ntop6(const u_char *src, char *dst, size_t size)
109{
110	/*
111	 * Note that int32_t and int16_t need only be "at least" large enough
112	 * to contain a value of the specified size.  On some systems, like
113	 * Crays, there is no such thing as an integer variable with 16 bits.
114	 * Keep this in mind if you think this function should have been coded
115	 * to use pointer overlays.  All the world's not a VAX.
116	 */
117	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
118	char *tp, *ep;
119	struct { int base, len; } best, cur;
120	u_int words[IN6ADDRSZ / INT16SZ];
121	int i;
122	int advance;
123
124	/*
125	 * Preprocess:
126	 *	Copy the input (bytewise) array into a wordwise array.
127	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
128	 */
129	memset(words, '\0', sizeof words);
130	for (i = 0; i < IN6ADDRSZ; i++)
131		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
132	best.base = -1;
133	cur.base = -1;
134	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
135		if (words[i] == 0) {
136			if (cur.base == -1)
137				cur.base = i, cur.len = 1;
138			else
139				cur.len++;
140		} else {
141			if (cur.base != -1) {
142				if (best.base == -1 || cur.len > best.len)
143					best = cur;
144				cur.base = -1;
145			}
146		}
147	}
148	if (cur.base != -1) {
149		if (best.base == -1 || cur.len > best.len)
150			best = cur;
151	}
152	if (best.base != -1 && best.len < 2)
153		best.base = -1;
154
155	/*
156	 * Format the result.
157	 */
158	tp = tmp;
159	ep = tmp + sizeof(tmp);
160	for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
161		/* Are we inside the best run of 0x00's? */
162		if (best.base != -1 && i >= best.base &&
163		    i < (best.base + best.len)) {
164			if (i == best.base) {
165				if (tp + 1 >= ep)
166					return (NULL);
167				*tp++ = ':';
168			}
169			continue;
170		}
171		/* Are we following an initial run of 0x00s or any real hex? */
172		if (i != 0) {
173			if (tp + 1 >= ep)
174				return (NULL);
175			*tp++ = ':';
176		}
177		/* Is this address an encapsulated IPv4? */
178		if (i == 6 && best.base == 0 &&
179		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
180			if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
181				return (NULL);
182			tp += strlen(tp);
183			break;
184		}
185		advance = snprintf(tp, ep - tp, "%x", words[i]);
186		if (advance <= 0 || advance >= ep - tp)
187			return (NULL);
188		tp += advance;
189	}
190	/* Was it a trailing run of 0x00's? */
191	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
192		if (tp + 1 >= ep)
193			return (NULL);
194		*tp++ = ':';
195	}
196	if (tp + 1 >= ep)
197		return (NULL);
198	*tp++ = '\0';
199
200	/*
201	 * Check for overflow, copy, and we're done.
202	 */
203	if ((size_t)(tp - tmp) > size) {
204		errno = ENOSPC;
205		return (NULL);
206	}
207	strlcpy(dst, tmp, size);
208	return (dst);
209}
210
211#endif /* !HAVE_INET_NTOP */
212