Source File ip/inet_ntop.c

    1    | /*	$OpenBSD: inet_ntop.c,v 1.1 1997/03/13 19:07:32 downsj 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   | #define __P(a) a
    19   |
    20   | #if defined(LIBC_SCCS) && !defined(lint)
    21   | #if 0
    22   | static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $";
    23   | #else
    24   | static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.1 1997/03/13 19:07:32 downsj Exp $";
    25   | #endif
    26   | #endif /* LIBC_SCCS and not lint */
    27   |
    28   | #include <sys/param.h>
    29   | #include <sys/types.h>
    30   | #include <sys/socket.h>
    31   | #include <netinet/in.h>
    32   | #include <arpa/inet.h>
    33   | #include <arpa/nameser.h>
    34   |
    35   | #include <string.h>
    36   | #include <errno.h>
    37   | #include <stdio.h>
    38   |
    39   | #include "inet6def.h"
    40   |
    41   | /*
    42   |  * WARNING: Don't even consider trying to compile this on a system where
    43   |  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
    44   |  */
    45   |
    46   | static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size));
    47   | static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size));
    48   |
    49   | /* char *
    50   |  * inet_ntop(af, src, dst, size)
    51   |  *	convert a network format address to presentation format.
    52   |  * return:
    53   |  *	pointer to presentation format address (`dst'), or NULL (see errno).
    54   |  * author:
    55   |  *	Paul Vixie, 1996.
    56   |  */
    57   | const char *
    58   | inet_ntop(af, src, dst, size)
    59   | 	int af;
    60   | 	const void *src;
    61   | 	char *dst;
    62   | 	size_t size;
    63   | {
    64   | 	switch (af) {
    65   | 	case AF_INET:
    66   | 		return (inet_ntop4(src, dst, size));
    67   | 	case AF_INET6:
    68   | 		return (inet_ntop6(src, dst, size));
    69   | 	default:
    70   | 		errno = EAFNOSUPPORT;
    71   | 		return (NULL);
    72   | 	}
    73   | 	/* NOTREACHED */
    74   | }
    75   |
    76   | /* const char *
    77   |  * inet_ntop4(src, dst, size)
    78   |  *	format an IPv4 address, more or less like inet_ntoa()
    79   |  * return:
    80   |  *	`dst' (as a const)
    81   |  * notes:
    82   |  *	(1) uses no statics
    83   |  *	(2) takes a u_char* not an in_addr as input
    84   |  * author:
    85   |  *	Paul Vixie, 1996.
    86   |  */
    87   | static const char *
    88   | inet_ntop4(src, dst, size)
    89   | 	const u_char *src;
    90   | 	char *dst;
    91   | 	size_t size;
    92   | {
    93   | 	static const char fmt[] = "%u.%u.%u.%u";
    94   | 	char tmp[sizeof "255.255.255.255"];
    95   |
    96   | 	if (sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) > size) {
    97   | 		errno = ENOSPC;
    98   | 		return (NULL);
    99   | 	}
    100  | 	strcpy(dst, tmp);
    101  | 	return (dst);
    102  | }
    103  |
    104  | /* const char *
    105  |  * inet_ntop6(src, dst, size)
    106  |  *	convert IPv6 binary address into presentation (printable) format
    107  |  * author:
    108  |  *	Paul Vixie, 1996.
    109  |  */
    110  | static const char *
    111  | inet_ntop6(src, dst, size)
    112  | 	const u_char *src;
    113  | 	char *dst;
    114  | 	size_t size;
    115  | {
    116  | 	/*
    117  | 	 * Note that int32_t and int16_t need only be "at least" large enough
    118  | 	 * to contain a value of the specified size.  On some systems, like
    119  | 	 * Crays, there is no such thing as an integer variable with 16 bits.
    120  | 	 * Keep this in mind if you think this function should have been coded
    121  | 	 * to use pointer overlays.  All the world's not a VAX.
    122  | 	 */
    123  | 	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
    124  | 	struct { int base, len; } best, cur;
    125  | 	u_int words[IN6ADDRSZ / INT16SZ];
    126  | 	int i;
    127  |
    128  | 	/*
    129  | 	 * Preprocess:
    130  | 	 *	Copy the input (bytewise) array into a wordwise array.
    131  | 	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
    132  | 	 */
    133  | 	memset(words, '\0', sizeof words);
    134  | 	for (i = 0; i < IN6ADDRSZ; i++)
    135  | 		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
    136  | 	best.base = -1;
    137  | 	cur.base = -1;
    138  | 	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
    139  | 		if (words[i] == 0) {
    140  | 			if (cur.base == -1)
    141  | 				cur.base = i, cur.len = 1;
    142  | 			else
    143  | 				cur.len++;
    144  | 		} else {
    145  | 			if (cur.base != -1) {
    146  | 				if (best.base == -1 || cur.len > best.len)
    147  | 					best = cur;
    148  | 				cur.base = -1;
    149  | 			}
    150  | 		}
    151  | 	}
    152  | 	if (cur.base != -1) {
    153  | 		if (best.base == -1 || cur.len > best.len)
    154  | 			best = cur;
    155  | 	}
    156  | 	if (best.base != -1 && best.len < 2)
    157  | 		best.base = -1;
    158  |
    159  | 	/*
    160  | 	 * Format the result.
    161  | 	 */
    162  | 	tp = tmp;
    163  | 	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
    164  | 		/* Are we inside the best run of 0x00's? */
    165  | 		if (best.base != -1 && i >= best.base &&
    166  | 		    i < (best.base + best.len)) {
    167  | 			if (i == best.base)
    168  | 				*tp++ = ':';
    169  | 			continue;
    170  | 		}
    171  | 		/* Are we following an initial run of 0x00s or any real hex? */
    172  | 		if (i != 0)
    173  | 			*tp++ = ':';
    174  | 		/* Is this address an encapsulated IPv4? */
    175  | 		if (i == 6 && best.base == 0 &&
    176  | 		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
    177  | 			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
    178  | 				return (NULL);
    179  | 			tp += strlen(tp);
    180  | 			break;
    181  | 		}
    182  | 		tp += sprintf(tp, "%x", words[i]);
    183  | 	}
    184  | 	/* Was it a trailing run of 0x00's? */
    185  | 	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
    186  | 		*tp++ = ':';
    187  | 	*tp++ = '\0';
    188  |
    189  | 	/*
    190  | 	 * Check for overflow, copy, and we're done.
    191  | 	 */
    192  | 	if ((size_t)(tp - tmp) > size) {
    193  | 		errno = ENOSPC;
    194  | 		return (NULL);
    195  | 	}
    196  | 	strcpy(dst, tmp);
    197  | 	return (dst);
    198  | }