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https://github.com/matrix-construct/construct
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63 lines
2.2 KiB
C
63 lines
2.2 KiB
C
/*
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* charybdis: A slightly useful ircd.
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* ipv4_from_ipv6.c: Finds IPv4 addresses behind IPv6 transition technologies
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*
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* Copyright (C) 2012 Jilles Tjoelker
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "stdinc.h"
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#include "ipv4_from_ipv6.h"
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#ifdef RB_IPV6
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int
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ipv4_from_ipv6(const struct sockaddr_in6 *restrict ip6,
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struct sockaddr_in *restrict ip4)
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{
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int i;
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if (!memcmp(ip6->sin6_addr.s6_addr, "\x20\x02", 2))
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{
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/* 6to4 and similar */
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memcpy(&ip4->sin_addr, ip6->sin6_addr.s6_addr + 2, 4);
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}
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else if (!memcmp(ip6->sin6_addr.s6_addr, "\x20\x01\x00\x00", 4))
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{
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/* Teredo */
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for (i = 0; i < 4; i++)
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((uint8_t *)&ip4->sin_addr)[i] = 0xFF ^
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ip6->sin6_addr.s6_addr[12 + i];
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}
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else
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return 0;
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SET_SS_LEN(ip4, sizeof(struct sockaddr_in));
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ip4->sin_family = AF_INET;
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ip4->sin_port = 0;
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return 1;
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}
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#endif /* RB_IPV6 */
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