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* Copyright (C) 1996-2001 Internet Software Consortium.
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
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* DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
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* INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
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* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
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* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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#if defined(LIBC_SCCS) && !defined(lint)
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"$Id: inet_ntop.c,v 1.13 2001/11/27 01:56:00 gson Exp $";
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#endif /* LIBC_SCCS and not lint */
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#include "ntp_sprintf.h"
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#define NS_IN6ADDRSZ 16
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* WARNING: Don't even consider trying to compile this on a system where
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* sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
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static const char *inet_ntop4(const unsigned char *src, char *dst,
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static const char *inet_ntop6(const unsigned char *src, char *dst,
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* isc_net_ntop(af, src, dst, size)
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* convert a network format address to presentation format.
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* pointer to presentation format address (`dst'), or NULL (see errno).
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isc_net_ntop(int af, const void *src, char *dst, size_t size)
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return (inet_ntop4(src, dst, size));
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return (inet_ntop6(src, dst, size));
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* inet_ntop4(src, dst, size)
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* format an IPv4 address
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* (2) takes a unsigned char* not an in_addr as input
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inet_ntop4(const unsigned char *src, char *dst, size_t size)
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static const char *fmt = "%u.%u.%u.%u";
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char tmp[sizeof("255.255.255.255")];
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if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size)
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* isc_inet_ntop6(src, dst, size)
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* convert IPv6 binary address into presentation (printable) format
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inet_ntop6(const unsigned char *src, char *dst, size_t size)
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* Note that int32_t and int16_t need only be "at least" large enough
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* to contain a value of the specified size. On some systems, like
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* Crays, there is no such thing as an integer variable with 16 bits.
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* Keep this in mind if you think this function should have been coded
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* to use pointer overlays. All the world's not a VAX.
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char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
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struct { int base, len; } best, cur;
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unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
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* Copy the input (bytewise) array into a wordwise array.
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* Find the longest run of 0x00's in src[] for :: shorthanding.
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memset(words, '\0', sizeof(words));
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for (i = 0; i < NS_IN6ADDRSZ; i++)
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words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
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for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
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cur.base = i, cur.len = 1;
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if (cur.base != -1) {
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if (best.base == -1 || cur.len > best.len)
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if (cur.base != -1) {
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if (best.base == -1 || cur.len > best.len)
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if (best.base != -1 && best.len < 2)
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for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
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/* Are we inside the best run of 0x00's? */
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if (best.base != -1 && i >= best.base &&
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i < (best.base + best.len)) {
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/* Are we following an initial run of 0x00s or any real hex? */
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/* Is this address an encapsulated IPv4? */
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if (i == 6 && best.base == 0 &&
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(best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
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if (!inet_ntop4(src+12, tp,
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sizeof(tmp) - (tp - tmp)))
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tp += SPRINTF((tp, "%x", words[i]));
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/* Was it a trailing run of 0x00's? */
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if (best.base != -1 && (best.base + best.len) ==
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(NS_IN6ADDRSZ / NS_INT16SZ))
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* Check for overflow, copy, and we're done.
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if ((size_t)(tp - tmp) > size) {
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#endif /* AF_INET6 */