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inet_net_ntop.c revision 1.2 
      1 /*
      2  * Copyright (c) 1996,1999 by 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 DISCLAIMS
      9  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
     10  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
     11  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
     12  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
     13  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
     14  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
     15  * SOFTWARE.
     16  */
     17 
     18 #include <sys/cdefs.h>
     19 #if defined(LIBC_SCCS) && !defined(lint)
     20 #ifdef notdef
     21 static const char rcsid[] = "Id: inet_net_ntop.c,v 1.1.2.1 2002/08/02 02:17:21 marka Exp ";
     22 #else
     23 __RCSID("$NetBSD: inet_net_ntop.c,v 1.2 2009/02/07 07:25:22 lukem Exp $");
     24 #endif
     25 #endif
     26 
     27 #include "port_before.h"
     28 
     29 #include "namespace.h"
     30 #include <sys/types.h>
     31 #include <sys/socket.h>
     32 #include <netinet/in.h>
     33 #include <arpa/inet.h>
     34 
     35 #include <errno.h>
     36 #include <stdio.h>
     37 #include <string.h>
     38 #include <stdlib.h>
     39 
     40 #include "port_after.h"
     41 
     42 #ifdef __weak_alias
     43 __weak_alias(inet_net_ntop,_inet_net_ntop)
     44 #endif
     45 
     46 #ifdef SPRINTF_CHAR
     47 # define SPRINTF(x) strlen(sprintf/**/x)
     48 #else
     49 # define SPRINTF(x) sprintf x
     50 #endif
     51 
     52 static char *	inet_net_ntop_ipv4 __P((const u_char *src, int bits,
     53 					char *dst, size_t size));
     54 static char *	inet_net_ntop_ipv6 __P((const u_char *src, int bits,
     55 					char *dst, size_t size));
     56 
     57 /*
     58  * char *
     59  * inet_net_ntop(af, src, bits, dst, size)
     60  *	convert network number from network to presentation format.
     61  *	generates CIDR style result always.
     62  * return:
     63  *	pointer to dst, or NULL if an error occurred (check errno).
     64  * author:
     65  *	Paul Vixie (ISC), July 1996
     66  */
     67 char *
     68 inet_net_ntop(af, src, bits, dst, size)
     69 	int af;
     70 	const void *src;
     71 	int bits;
     72 	char *dst;
     73 	size_t size;
     74 {
     75 	switch (af) {
     76 	case AF_INET:
     77 		return (inet_net_ntop_ipv4(src, bits, dst, size));
     78 	case AF_INET6:
     79 		return (inet_net_ntop_ipv6(src, bits, dst, size));
     80 	default:
     81 		errno = EAFNOSUPPORT;
     82 		return (NULL);
     83 	}
     84 }
     85 
     86 /*
     87  * static char *
     88  * inet_net_ntop_ipv4(src, bits, dst, size)
     89  *	convert IPv4 network number from network to presentation format.
     90  *	generates CIDR style result always.
     91  * return:
     92  *	pointer to dst, or NULL if an error occurred (check errno).
     93  * note:
     94  *	network byte order assumed.  this means 192.5.5.240/28 has
     95  *	0b11110000 in its fourth octet.
     96  * author:
     97  *	Paul Vixie (ISC), July 1996
     98  */
     99 static char *
    100 inet_net_ntop_ipv4(src, bits, dst, size)
    101 	const u_char *src;
    102 	int bits;
    103 	char *dst;
    104 	size_t size;
    105 {
    106 	char *odst = dst;
    107 	char *t;
    108 	u_int m;
    109 	int b;
    110 
    111 	if (bits < 0 || bits > 32) {
    112 		errno = EINVAL;
    113 		return (NULL);
    114 	}
    115 
    116 	if (bits == 0) {
    117 		if (size < sizeof "0")
    118 			goto emsgsize;
    119 		*dst++ = '0';
    120 		size--;
    121 		*dst = '\0';
    122 	}
    123 
    124 	/* Format whole octets. */
    125 	for (b = bits / 8; b > 0; b--) {
    126 		if (size <= sizeof "255.")
    127 			goto emsgsize;
    128 		t = dst;
    129 		dst += SPRINTF((dst, "%u", *src++));
    130 		if (b > 1) {
    131 			*dst++ = '.';
    132 			*dst = '\0';
    133 		}
    134 		size -= (size_t)(dst - t);
    135 	}
    136 
    137 	/* Format partial octet. */
    138 	b = bits % 8;
    139 	if (b > 0) {
    140 		if (size <= sizeof ".255")
    141 			goto emsgsize;
    142 		t = dst;
    143 		if (dst != odst)
    144 			*dst++ = '.';
    145 		m = ((1 << b) - 1) << (8 - b);
    146 		dst += SPRINTF((dst, "%u", *src & m));
    147 		size -= (size_t)(dst - t);
    148 	}
    149 
    150 	/* Format CIDR /width. */
    151 	if (size <= sizeof "/32")
    152 		goto emsgsize;
    153 	dst += SPRINTF((dst, "/%u", bits));
    154 	return (odst);
    155 
    156  emsgsize:
    157 	errno = EMSGSIZE;
    158 	return (NULL);
    159 }
    160 
    161 /*
    162  * static char *
    163  * inet_net_ntop_ipv6(src, bits, fakebits, dst, size)
    164  *	convert IPv6 network number from network to presentation format.
    165  *	generates CIDR style result always. Picks the shortest representation
    166  *	unless the IP is really IPv4.
    167  *	always prints specified number of bits (bits).
    168  * return:
    169  *	pointer to dst, or NULL if an error occurred (check errno).
    170  * note:
    171  *	network byte order assumed.  this means 192.5.5.240/28 has
    172  *	0x11110000 in its fourth octet.
    173  * author:
    174  *	Vadim Kogan (UCB), June 2001
    175  *  Original version (IPv4) by Paul Vixie (ISC), July 1996
    176  */
    177 
    178 static char *
    179 inet_net_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
    180 	u_int	m;
    181 	int	b;
    182 	size_t	p;
    183 	size_t	zero_s, zero_l, tmp_zero_s, tmp_zero_l;
    184 	size_t	i;
    185 	int	is_ipv4 = 0;
    186 	unsigned char inbuf[16];
    187 	char outbuf[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];
    188 	char	*cp;
    189 	size_t	words;
    190 	u_char	*s;
    191 
    192 	if (bits < 0 || bits > 128) {
    193 		errno = EINVAL;
    194 		return (NULL);
    195 	}
    196 
    197 	cp = outbuf;
    198 
    199 	if (bits == 0) {
    200 		*cp++ = ':';
    201 		*cp++ = ':';
    202 		*cp = '\0';
    203 	} else {
    204 		/* Copy src to private buffer.  Zero host part. */
    205 		p = (bits + 7) / 8;
    206 		memcpy(inbuf, src, p);
    207 		memset(inbuf + p, 0, 16 - p);
    208 		b = bits % 8;
    209 		if (b != 0) {
    210 			m = ~0 << (8 - b);
    211 			inbuf[p-1] &= m;
    212 		}
    213 
    214 		s = inbuf;
    215 
    216 		/* how many words need to be displayed in output */
    217 		words = (bits + 15) / 16;
    218 		if (words == 1)
    219 			words = 2;
    220 
    221 		/* Find the longest substring of zero's */
    222 		zero_s = zero_l = tmp_zero_s = tmp_zero_l = 0;
    223 		for (i = 0; i < (words * 2); i += 2) {
    224 			if ((s[i] | s[i+1]) == 0) {
    225 				if (tmp_zero_l == 0)
    226 					tmp_zero_s = i / 2;
    227 				tmp_zero_l++;
    228 			} else {
    229 				if (tmp_zero_l && zero_l < tmp_zero_l) {
    230 					zero_s = tmp_zero_s;
    231 					zero_l = tmp_zero_l;
    232 					tmp_zero_l = 0;
    233 				}
    234 			}
    235 		}
    236 
    237 		if (tmp_zero_l && zero_l < tmp_zero_l) {
    238 			zero_s = tmp_zero_s;
    239 			zero_l = tmp_zero_l;
    240 		}
    241 
    242 		if (zero_l != words && zero_s == 0 && ((zero_l == 6) ||
    243 		    ((zero_l == 5 && s[10] == 0xff && s[11] == 0xff) ||
    244 		    ((zero_l == 7 && s[14] != 0 && s[15] != 1)))))
    245 			is_ipv4 = 1;
    246 
    247 		/* Format whole words. */
    248 		for (p = 0; p < words; p++) {
    249 			if (zero_l != 0 && p >= zero_s && p < zero_s + zero_l) {
    250 				/* Time to skip some zeros */
    251 				if (p == zero_s)
    252 					*cp++ = ':';
    253 				if (p == words - 1)
    254 					*cp++ = ':';
    255 				s++;
    256 				s++;
    257 				continue;
    258 			}
    259 
    260 			if (is_ipv4 && p > 5 ) {
    261 				*cp++ = (p == 6) ? ':' : '.';
    262 				cp += SPRINTF((cp, "%u", *s++));
    263 				/* we can potentially drop the last octet */
    264 				if (p != 7 || bits > 120) {
    265 					*cp++ = '.';
    266 					cp += SPRINTF((cp, "%u", *s++));
    267 				}
    268 			} else {
    269 				if (cp != outbuf)
    270 					*cp++ = ':';
    271 				cp += SPRINTF((cp, "%x", *s * 256 + s[1]));
    272 				s += 2;
    273 			}
    274 		}
    275 	}
    276 	/* Format CIDR /width. */
    277 	(void)SPRINTF((cp, "/%u", bits));
    278 	if (strlen(outbuf) + 1 > size)
    279 		goto emsgsize;
    280 	strcpy(dst, outbuf);
    281 
    282 	return (dst);
    283 
    284 emsgsize:
    285 	errno = EMSGSIZE;
    286 	return (NULL);
    287 }
    288