/contrib/bind9/lib/lwres/lwinetntop.c

  1/*
  2 * Copyright (C) 2004, 2005, 2007  Internet Systems Consortium, Inc. ("ISC")
  3 * Copyright (C) 1996-2001, 2003  Internet Software Consortium.
  4 *
  5 * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
 10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 11 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 15 * PERFORMANCE OF THIS SOFTWARE.
 16 */
 17
 18/*! \file lwinetntop.c
 19 */
 20#if defined(LIBC_SCCS) && !defined(lint)
 21static char rcsid[] =
 22	"$Id: lwinetntop.c,v 1.18 2007/06/19 23:47:22 tbox Exp $";
 23#endif /* LIBC_SCCS and not lint */
 24
 25#include <config.h>
 26
 27#include <errno.h>
 28#include <stdio.h>
 29#include <string.h>
 30
 31#include <lwres/net.h>
 32#include "print_p.h"
 33
 34#define NS_INT16SZ	 2
 35#define NS_IN6ADDRSZ	16
 36
 37/*
 38 * WARNING: Don't even consider trying to compile this on a system where
 39 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
 40 */
 41
 42static const char *inet_ntop4(const unsigned char *src, char *dst,
 43			      size_t size);
 44
 45#ifdef AF_INET6
 46static const char *inet_ntop6(const unsigned char *src, char *dst,
 47			      size_t size);
 48#endif
 49
 50/*! char *
 51 * lwres_net_ntop(af, src, dst, size)
 52 *	convert a network format address to presentation format.
 53 * return:
 54 *	pointer to presentation format address (`dst'), or NULL (see errno).
 55 * author:
 56 *	Paul Vixie, 1996.
 57 */
 58const char *
 59lwres_net_ntop(int af, const void *src, char *dst, size_t size) {
 60	switch (af) {
 61	case AF_INET:
 62		return (inet_ntop4(src, dst, size));
 63#ifdef AF_INET6
 64	case AF_INET6:
 65		return (inet_ntop6(src, dst, size));
 66#endif
 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
 77 * return:
 78 *	`dst' (as a const)
 79 * notes:
 80 *	(1) uses no statics
 81 *	(2) takes a unsigned char* not an in_addr as input
 82 * author:
 83 *	Paul Vixie, 1996.
 84 */
 85static const char *
 86inet_ntop4(const unsigned char *src, char *dst, size_t size) {
 87	static const char fmt[] = "%u.%u.%u.%u";
 88	char tmp[sizeof("255.255.255.255")];
 89	size_t len;
 90
 91	len = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
 92	if (len >= size) {
 93		errno = ENOSPC;
 94		return (NULL);
 95	}
 96	strcpy(dst, tmp);
 97
 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 */
107#ifdef AF_INET6
108static const char *
109inet_ntop6(const unsigned char *src, char *dst, size_t size) {
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")], *tp;
118	struct { int base, len; } best, cur;
119	unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
120	int i;
121
122	/*
123	 * Preprocess:
124	 *	Copy the input (bytewise) array into a wordwise array.
125	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
126	 */
127	memset(words, '\0', sizeof(words));
128	for (i = 0; i < NS_IN6ADDRSZ; i++)
129		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
130	best.base = -1;
131	best.len = 0;
132	cur.base = -1;
133	cur.len = 0;
134	for (i = 0; i < (NS_IN6ADDRSZ / NS_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	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
160		/* Are we inside the best run of 0x00's? */
161		if (best.base != -1 && i >= best.base &&
162		    i < (best.base + best.len)) {
163			if (i == best.base)
164				*tp++ = ':';
165			continue;
166		}
167		/* Are we following an initial run of 0x00s or any real hex? */
168		if (i != 0)
169			*tp++ = ':';
170		/* Is this address an encapsulated IPv4? */
171		if (i == 6 && best.base == 0 &&
172		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
173			if (!inet_ntop4(src+12, tp,
174					sizeof(tmp) - (tp - tmp)))
175				return (NULL);
176			tp += strlen(tp);
177			break;
178		}
179		tp += sprintf(tp, "%x", words[i]); /* XXX */
180	}
181	/* Was it a trailing run of 0x00's? */
182	if (best.base != -1 && (best.base + best.len) ==
183	    (NS_IN6ADDRSZ / NS_INT16SZ))
184		*tp++ = ':';
185	*tp++ = '\0';
186
187	/*
188	 * Check for overflow, copy, and we're done.
189	 */
190	if ((size_t)(tp - tmp) > size) {
191		errno = ENOSPC;
192		return (NULL);
193	}
194	strcpy(dst, tmp);
195	return (dst);
196}
197#endif /* AF_INET6 */