1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright (c) 1996-2001 by Sun Microsystems, Inc. 24 * All rights reserved. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 #include <sys/types.h> 30 #include <strings.h> 31 #include <netinet/in.h> 32 #include "v4_sum_impl.h" 33 34 /* 35 * RFC 768 pseudo header. Used in calculating UDP checksums. 36 */ 37 struct pseudo_udp { 38 struct in_addr src; 39 struct in_addr dst; 40 uint8_t notused; /* always zero */ 41 uint8_t proto; /* protocol used */ 42 uint16_t len; /* UDP len */ 43 }; 44 45 /* 46 * One's complement checksum of pseudo header, udp header, and data. 47 * Must be MT SAFE. 48 */ 49 uint16_t 50 udp_chksum(struct udphdr *udph, const struct in_addr *src, 51 const struct in_addr *dst, uint8_t proto) 52 { 53 struct pseudo_udp ck; 54 uint16_t *end_pseudo_hdr = (uint16_t *)(&ck + 1); 55 uint16_t *sp = (uint16_t *)&ck; 56 uint_t sum = 0; 57 uint16_t cnt; 58 59 /* 60 * Start on the pseudo header. Note that pseudo_udp already takes 61 * acount for the udphdr... 62 */ 63 64 bzero(&ck, sizeof (ck)); 65 66 /* struct copies */ 67 ck.src = *src; 68 ck.dst = *dst; 69 ck.len = udph->uh_ulen; 70 ck.proto = proto; 71 72 /* 73 * If the packet is an odd length, zero the pad byte for checksum 74 * purposes [doesn't hurt data] 75 */ 76 77 cnt = ntohs(ck.len) + sizeof (ck); 78 if (cnt & 1) { 79 ((caddr_t)udph)[ntohs(udph->uh_ulen)] = '\0'; 80 cnt++; /* make even */ 81 } 82 83 for (cnt >>= 1; cnt != 0; cnt--) { 84 85 sum += *sp++; 86 if (sum >= BIT_WRAP) { 87 /* Wrap carries into low bit */ 88 sum -= BIT_WRAP; 89 sum++; 90 } 91 92 /* 93 * If we've finished checking the pseudo-header, move 94 * onto the udp header and data. 95 */ 96 97 if (sp == end_pseudo_hdr) 98 sp = (uint16_t *)udph; 99 } 100 101 return (~sum == 0 ? ~0 : ~sum); 102 } 103