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      1 /*
      2  * edns-subnet/edns-subnet.c - Subnet option related constants
      3  *
      4  * Copyright (c) 2013, NLnet Labs. All rights reserved.
      5  *
      6  * This software is open source.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  *
     12  * Redistributions of source code must retain the above copyright notice,
     13  * this list of conditions and the following disclaimer.
     14  *
     15  * Redistributions in binary form must reproduce the above copyright notice,
     16  * this list of conditions and the following disclaimer in the documentation
     17  * and/or other materials provided with the distribution.
     18  *
     19  * Neither the name of the NLNET LABS nor the names of its contributors may
     20  * be used to endorse or promote products derived from this software without
     21  * specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     24  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     26  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     27  * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
     29  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     30  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     31  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     32  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     33  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     34  */
     35 /**
     36  * \file
     37  * Subnet option related constants.
     38  */
     39 
     40 #include "config.h"
     41 
     42 #ifdef CLIENT_SUBNET /* keeps splint happy */
     43 #include "edns-subnet/edns-subnet.h"
     44 #include <string.h>
     45 
     46 int
     47 copy_clear(uint8_t* dst, size_t dstlen, uint8_t* src, size_t srclen, size_t n)
     48 {
     49 	size_t intpart = n / 8;  /* bytes */
     50 	size_t fracpart = n % 8; /* bits */
     51 	size_t written = intpart;
     52 	if (intpart > dstlen || intpart > srclen)
     53 		return 1;
     54 	if (fracpart && (intpart+1 > dstlen || intpart+1 > srclen))
     55 		return 1;
     56 	memcpy(dst, src, intpart);
     57 	if (fracpart) {
     58 		dst[intpart] = src[intpart] & ~(0xFF >> fracpart);
     59 		written++;
     60 	}
     61 	memset(dst + written, 0, dstlen - written);
     62 	return 0;
     63 }
     64 
     65 #endif /* CLIENT_SUBNET */
     66