sctp_crc32.c revision 234995
1/*- 2 * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved. 3 * Copyright (c) 2008-2011, by Randall Stewart. All rights reserved. 4 * Copyright (c) 2008-2011, by Michael Tuexen. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions are met: 8 * 9 * a) Redistributions of source code must retain the above copyright notice, 10 * this list of conditions and the following disclaimer. 11 * 12 * b) Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in 14 * the documentation and/or other materials provided with the distribution. 15 * 16 * c) Neither the name of Cisco Systems, Inc. nor the names of its 17 * contributors may be used to endorse or promote products derived 18 * from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 22 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 30 * THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33/* $KAME: sctp_crc32.c,v 1.12 2005/03/06 16:04:17 itojun Exp $ */ 34 35 36#include <sys/cdefs.h> 37__FBSDID("$FreeBSD: head/sys/netinet/sctp_crc32.c 234995 2012-05-04 09:27:00Z tuexen $"); 38 39#include <netinet/sctp_os.h> 40#include <netinet/sctp.h> 41#include <netinet/sctp_crc32.h> 42#include <netinet/sctp_pcb.h> 43 44 45#if !defined(SCTP_WITH_NO_CSUM) 46 47static uint32_t 48sctp_finalize_crc32c(uint32_t crc32c) 49{ 50 uint32_t result; 51 52#if BYTE_ORDER == BIG_ENDIAN 53 uint8_t byte0, byte1, byte2, byte3; 54 55#endif 56 /* Complement the result */ 57 result = ~crc32c; 58#if BYTE_ORDER == BIG_ENDIAN 59 /* 60 * For BIG-ENDIAN.. aka Motorola byte order the result is in 61 * little-endian form. So we must manually swap the bytes. Then we 62 * can call htonl() which does nothing... 63 */ 64 byte0 = result & 0x000000ff; 65 byte1 = (result >> 8) & 0x000000ff; 66 byte2 = (result >> 16) & 0x000000ff; 67 byte3 = (result >> 24) & 0x000000ff; 68 crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3); 69#else 70 /* 71 * For INTEL platforms the result comes out in network order. No 72 * htonl is required or the swap above. So we optimize out both the 73 * htonl and the manual swap above. 74 */ 75 crc32c = result; 76#endif 77 return (crc32c); 78} 79 80uint32_t 81sctp_calculate_cksum(struct mbuf *m, uint32_t offset) 82{ 83 /* 84 * given a mbuf chain with a packetheader offset by 'offset' 85 * pointing at a sctphdr (with csum set to 0) go through the chain 86 * of SCTP_BUF_NEXT()'s and calculate the SCTP checksum. This also 87 * has a side bonus as it will calculate the total length of the 88 * mbuf chain. Note: if offset is greater than the total mbuf 89 * length, checksum=1, pktlen=0 is returned (ie. no real error code) 90 */ 91 uint32_t base = 0xffffffff; 92 struct mbuf *at; 93 94 at = m; 95 /* find the correct mbuf and offset into mbuf */ 96 while ((at != NULL) && (offset > (uint32_t) SCTP_BUF_LEN(at))) { 97 offset -= SCTP_BUF_LEN(at); /* update remaining offset 98 * left */ 99 at = SCTP_BUF_NEXT(at); 100 } 101 while (at != NULL) { 102 if ((SCTP_BUF_LEN(at) - offset) > 0) { 103 base = calculate_crc32c(base, 104 (unsigned char *)(SCTP_BUF_AT(at, offset)), 105 (unsigned int)(SCTP_BUF_LEN(at) - offset)); 106 } 107 if (offset) { 108 /* we only offset once into the first mbuf */ 109 if (offset < (uint32_t) SCTP_BUF_LEN(at)) 110 offset = 0; 111 else 112 offset -= SCTP_BUF_LEN(at); 113 } 114 at = SCTP_BUF_NEXT(at); 115 } 116 base = sctp_finalize_crc32c(base); 117 return (base); 118} 119 120#endif /* !defined(SCTP_WITH_NO_CSUM) */ 121 122 123void 124sctp_delayed_cksum(struct mbuf *m, uint32_t offset) 125{ 126#if defined(SCTP_WITH_NO_CSUM) 127 panic("sctp_delayed_cksum() called when using no SCTP CRC."); 128#else 129 uint32_t checksum; 130 131 checksum = sctp_calculate_cksum(m, offset); 132 SCTP_STAT_DECR(sctps_sendhwcrc); 133 SCTP_STAT_INCR(sctps_sendswcrc); 134 offset += offsetof(struct sctphdr, checksum); 135 136 if (offset + sizeof(uint32_t) > (uint32_t) (m->m_len)) { 137 SCTP_PRINTF("sctp_delayed_cksum(): m->len: %d, off: %d.\n", 138 (uint32_t) m->m_len, offset); 139 /* 140 * XXX this shouldn't happen, but if it does, the correct 141 * behavior may be to insert the checksum in the appropriate 142 * next mbuf in the chain. 143 */ 144 return; 145 } 146 *(uint32_t *) (m->m_data + offset) = checksum; 147#endif 148} 149