1/*
2 * Copyright (C) 1996-2001  Internet Software Consortium.
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
9 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
10 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
11 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
13 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
14 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
15 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18
19#include "replace.h"
20#include "system/network.h"
21
22#define NS_INT16SZ	 2
23#define NS_IN6ADDRSZ	16
24
25/*
26 * WARNING: Don't even consider trying to compile this on a system where
27 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
28 */
29
30static const char *inet_ntop4(const unsigned char *src, char *dst,
31			      socklen_t size);
32
33#ifdef AF_INET6
34static const char *inet_ntop6(const unsigned char *src, char *dst,
35			      socklen_t size);
36#endif
37
38/* char *
39 * isc_net_ntop(af, src, dst, size)
40 *	convert a network format address to presentation format.
41 * return:
42 *	pointer to presentation format address (`dst'), or NULL (see errno).
43 * author:
44 *	Paul Vixie, 1996.
45 */
46const char *
47rep_inet_ntop(int af, const void *src, char *dst, socklen_t size)
48{
49	switch (af) {
50	case AF_INET:
51		return (inet_ntop4(src, dst, size));
52#ifdef AF_INET6
53	case AF_INET6:
54		return (inet_ntop6(src, dst, size));
55#endif
56	default:
57		errno = EAFNOSUPPORT;
58		return (NULL);
59	}
60	/* NOTREACHED */
61}
62
63/* const char *
64 * inet_ntop4(src, dst, size)
65 *	format an IPv4 address
66 * return:
67 *	`dst' (as a const)
68 * notes:
69 *	(1) uses no statics
70 *	(2) takes a unsigned char* not an in_addr as input
71 * author:
72 *	Paul Vixie, 1996.
73 */
74static const char *
75inet_ntop4(const unsigned char *src, char *dst, socklen_t size)
76{
77	static const char *fmt = "%u.%u.%u.%u";
78	char tmp[sizeof "255.255.255.255"];
79	size_t len;
80
81	len = snprintf(tmp, sizeof tmp, fmt, src[0], src[1], src[2], src[3]);
82	if (len >= size) {
83		errno = ENOSPC;
84		return (NULL);
85	}
86	memcpy(dst, tmp, len + 1);
87
88	return (dst);
89}
90
91/* const char *
92 * isc_inet_ntop6(src, dst, size)
93 *	convert IPv6 binary address into presentation (printable) format
94 * author:
95 *	Paul Vixie, 1996.
96 */
97#ifdef AF_INET6
98static const char *
99inet_ntop6(const unsigned char *src, char *dst, socklen_t size)
100{
101	/*
102	 * Note that int32_t and int16_t need only be "at least" large enough
103	 * to contain a value of the specified size.  On some systems, like
104	 * Crays, there is no such thing as an integer variable with 16 bits.
105	 * Keep this in mind if you think this function should have been coded
106	 * to use pointer overlays.  All the world's not a VAX.
107	 */
108	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
109	struct { int base, len; } best, cur;
110	unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
111	int i, inc;
112
113	/*
114	 * Preprocess:
115	 *	Copy the input (bytewise) array into a wordwise array.
116	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
117	 */
118	memset(words, '\0', sizeof words);
119	for (i = 0; i < NS_IN6ADDRSZ; i++)
120		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
121	best.base = -1;
122	best.len = 0;
123	cur.base = -1;
124	cur.len = 0;
125	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
126		if (words[i] == 0) {
127			if (cur.base == -1)
128				cur.base = i, cur.len = 1;
129			else
130				cur.len++;
131		} else {
132			if (cur.base != -1) {
133				if (best.base == -1 || cur.len > best.len)
134					best = cur;
135				cur.base = -1;
136			}
137		}
138	}
139	if (cur.base != -1) {
140		if (best.base == -1 || cur.len > best.len)
141			best = cur;
142	}
143	if (best.base != -1 && best.len < 2)
144		best.base = -1;
145
146	/*
147	 * Format the result.
148	 */
149	tp = tmp;
150	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
151		/* Are we inside the best run of 0x00's? */
152		if (best.base != -1 && i >= best.base &&
153		    i < (best.base + best.len)) {
154			if (i == best.base)
155				*tp++ = ':';
156			continue;
157		}
158		/* Are we following an initial run of 0x00s or any real hex? */
159		if (i != 0)
160			*tp++ = ':';
161		/* Is this address an encapsulated IPv4? */
162		if (i == 6 && best.base == 0 &&
163		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
164			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
165				return (NULL);
166			tp += strlen(tp);
167			break;
168		}
169		inc = snprintf(tp, 5, "%x", words[i]);
170		if (inc >= 5) {
171			abort();
172		}
173		tp += inc;
174	}
175	/* Was it a trailing run of 0x00's? */
176	if (best.base != -1 && (best.base + best.len) ==
177	    (NS_IN6ADDRSZ / NS_INT16SZ))
178		*tp++ = ':';
179	*tp++ = '\0';
180
181	/*
182	 * Check for overflow, copy, and we're done.
183	 */
184	if ((size_t)(tp - tmp) > size) {
185		errno = ENOSPC;
186		return (NULL);
187	}
188	memcpy(dst, tmp, tp - tmp);
189	return (dst);
190}
191#endif /* AF_INET6 */
192