1 /* inet_ntop.c -- convert IPv4 and IPv6 addresses from binary to text form
3 Copyright (C) 2005-2006, 2008-2011 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
20 * Copyright (c) 1996-1999 by Internet Software Consortium.
22 * Permission to use, copy, modify, and distribute this software for any
23 * purpose with or without fee is hereby granted, provided that the above
24 * copyright notice and this permission notice appear in all copies.
26 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
27 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
29 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
30 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
31 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
32 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
39 #include <arpa/inet.h>
45 #define NS_IN6ADDRSZ 16
49 * WARNING: Don't even consider trying to compile this on a system where
50 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
52 typedef int verify_int_size[4 <= sizeof (int) ? 1 : -1];
54 static const char *inet_ntop4 (const unsigned char *src, char *dst, socklen_t size);
56 static const char *inet_ntop6 (const unsigned char *src, char *dst, socklen_t size);
61 * inet_ntop(af, src, dst, size)
62 * convert a network format address to presentation format.
64 * pointer to presentation format address (`dst'), or NULL (see errno).
69 inet_ntop (int af, const void *restrict src,
70 char *restrict dst, socklen_t cnt)
76 return (inet_ntop4 (src, dst, cnt));
81 return (inet_ntop6 (src, dst, cnt));
92 * inet_ntop4(src, dst, size)
93 * format an IPv4 address
98 * (2) takes a u_char* not an in_addr as input
103 inet_ntop4 (const unsigned char *src, char *dst, socklen_t size)
105 char tmp[sizeof "255.255.255.255"];
108 len = sprintf (tmp, "%u.%u.%u.%u", src[0], src[1], src[2], src[3]);
118 return strcpy (dst, tmp);
124 * inet_ntop6(src, dst, size)
125 * convert IPv6 binary address into presentation (printable) format
130 inet_ntop6 (const unsigned char *src, char *dst, socklen_t size)
133 * Note that int32_t and int16_t need only be "at least" large enough
134 * to contain a value of the specified size. On some systems, like
135 * Crays, there is no such thing as an integer variable with 16 bits.
136 * Keep this in mind if you think this function should have been coded
137 * to use pointer overlays. All the world's not a VAX.
139 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
144 unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
149 * Copy the input (bytewise) array into a wordwise array.
150 * Find the longest run of 0x00's in src[] for :: shorthanding.
152 memset (words, '\0', sizeof words);
153 for (i = 0; i < NS_IN6ADDRSZ; i += 2)
154 words[i / 2] = (src[i] << 8) | src[i + 1];
157 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
162 cur.base = i, cur.len = 1;
170 if (best.base == -1 || cur.len > best.len)
178 if (best.base == -1 || cur.len > best.len)
181 if (best.base != -1 && best.len < 2)
188 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)
190 /* Are we inside the best run of 0x00's? */
191 if (best.base != -1 && i >= best.base && i < (best.base + best.len))
197 /* Are we following an initial run of 0x00s or any real hex? */
200 /* Is this address an encapsulated IPv4? */
201 if (i == 6 && best.base == 0 &&
202 (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
204 if (!inet_ntop4 (src + 12, tp, sizeof tmp - (tp - tmp)))
210 int len = sprintf (tp, "%x", words[i]);
216 /* Was it a trailing run of 0x00's? */
217 if (best.base != -1 && (best.base + best.len) ==
218 (NS_IN6ADDRSZ / NS_INT16SZ))
223 * Check for overflow, copy, and we're done.
225 if ((socklen_t) (tp - tmp) > size)
231 return strcpy (dst, tmp);