/* $OpenBSD: in4_cksum.c,v 1.11 2022/02/01 15:30:10 miod Exp $ */ /* $KAME: in4_cksum.c,v 1.10 2001/11/30 10:06:15 itojun Exp $ */ /* $NetBSD: in_cksum.c,v 1.13 1996/10/13 02:03:03 christos Exp $ */ /* * Copyright (C) 1999 WIDE Project. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * Copyright (c) 1988, 1992, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 */ #include <sys/param.h> #include <sys/mbuf.h> #include <sys/systm.h> #include <sys/socket.h> #include <sys/socketvar.h> #include <netinet/in.h> #include <netinet/ip.h> #include <netinet/ip_var.h> /* * Checksum routine for Internet Protocol family headers (Portable Version). * This is only for IPv4 pseudo header checksum. * No need to clear non-pseudo-header fields in IPv4 header. * len is for actual payload size, and does not include IPv4 header and * skipped header chain (off + len should be equal to the whole packet). * * This routine is very heavily used in the network * code and should be modified for each CPU to be as fast as possible. */ #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} int in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len) { u_int16_t *w; int sum = 0; int mlen = 0; int byte_swapped = 0; union { struct ipovly ipov; u_int16_t w[10]; } u; union { u_int8_t c[2]; u_int16_t s; } s_util; union { u_int16_t s[2]; u_int32_t l; } l_util; if (nxt != 0) { /* pseudo header */ if (off < sizeof(struct ipovly)) panic("in4_cksum: offset too short"); if (m->m_len < sizeof(struct ip)) panic("in4_cksum: bad mbuf chain"); u.ipov.ih_x1[8] = 0; u.ipov.ih_pr = nxt; u.ipov.ih_len = htons(len); u.ipov.ih_src = mtod(m, struct ip *)->ip_src; u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst; w = u.w; /* assumes sizeof(ipov) == 20 and first 8 bytes are zeroes */ sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9]; } /* skip unnecessary part */ while (m && off > 0) { if (m->m_len > off) break; off -= m->m_len; m = m->m_next; } for (;m && len; m = m->m_next) { if (m->m_len == 0) continue; w = (u_int16_t *)(mtod(m, caddr_t) + off); if (mlen == -1) { /* * The first byte of this mbuf is the continuation * of a word spanning between this mbuf and the * last mbuf. * * s_util.c[0] is already saved when scanning previous * mbuf. */ s_util.c[1] = *(u_int8_t *)w; sum += s_util.s; w = (u_int16_t *)((u_int8_t *)w + 1); mlen = m->m_len - off - 1; len--; } else mlen = m->m_len - off; off = 0; if (len < mlen) mlen = len; len -= mlen; /* * Force to even boundary. */ if ((1 & (long) w) && (mlen > 0)) { REDUCE; sum <<= 8; s_util.c[0] = *(u_int8_t *)w; w = (u_int16_t *)((int8_t *)w + 1); mlen--; byte_swapped = 1; } /* * Unroll the loop to make overhead from * branches &c small. */ while ((mlen -= 32) >= 0) { sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; w += 16; } mlen += 32; while ((mlen -= 8) >= 0) { sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; w += 4; } mlen += 8; if (mlen == 0 && byte_swapped == 0) continue; REDUCE; while ((mlen -= 2) >= 0) { sum += *w++; } if (byte_swapped) { REDUCE; sum <<= 8; byte_swapped = 0; if (mlen == -1) { s_util.c[1] = *(u_int8_t *)w; sum += s_util.s; mlen = 0; } else mlen = -1; } else if (mlen == -1) s_util.c[0] = *(u_int8_t *)w; } if (len) printf("cksum4: out of data\n"); if (mlen == -1) { /* The last mbuf has odd # of bytes. Follow the standard (the odd byte may be shifted left by 8 bits or not as determined by endian-ness of the machine) */ s_util.c[1] = 0; sum += s_util.s; } REDUCE; return (~sum & 0xffff); }
