Current Path : /sys/netinet/libalias/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
Current File : //sys/netinet/libalias/alias_util.c |
/*- * Copyright (c) 2001 Charles Mott <cm@linktel.net> * 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD: release/9.1.0/sys/netinet/libalias/alias_util.c 174348 2007-12-06 09:31:13Z des $"); /* Alias_util.c contains general utilities used by other functions in the packet aliasing module. At the moment, there are functions for computing IP header and TCP packet checksums. The checksum routines are based upon example code in a Unix networking text written by Stevens (sorry, I can't remember the title -- but at least this is a good author). Initial Version: August, 1996 (cjm) Version 1.7: January 9, 1997 Added differential checksum update function. */ #ifdef _KERNEL #include <sys/param.h> #include <sys/proc.h> #else #include <sys/types.h> #include <stdio.h> #endif #include <netinet/in_systm.h> #include <netinet/in.h> #include <netinet/ip.h> #include <netinet/tcp.h> #ifdef _KERNEL #include <netinet/libalias/alias.h> #include <netinet/libalias/alias_local.h> #else #include "alias.h" #include "alias_local.h" #endif /* * Note: the checksum routines assume that the actual checksum word has * been zeroed out. If the checksum word is filled with the proper value, * then these routines will give a result of zero (useful for testing * purposes); */ u_short LibAliasInternetChecksum(struct libalias *la __unused, u_short * ptr, int nbytes) { int sum, oddbyte; LIBALIAS_LOCK(la); sum = 0; while (nbytes > 1) { sum += *ptr++; nbytes -= 2; } if (nbytes == 1) { oddbyte = 0; ((u_char *) & oddbyte)[0] = *(u_char *) ptr; ((u_char *) & oddbyte)[1] = 0; sum += oddbyte; } sum = (sum >> 16) + (sum & 0xffff); sum += (sum >> 16); LIBALIAS_UNLOCK(la); return (~sum); } #ifndef _KERNEL u_short IpChecksum(struct ip *pip) { return (LibAliasInternetChecksum(NULL, (u_short *) pip, (pip->ip_hl << 2))); } u_short TcpChecksum(struct ip *pip) { u_short *ptr; struct tcphdr *tc; int nhdr, ntcp, nbytes; int sum, oddbyte; nhdr = pip->ip_hl << 2; ntcp = ntohs(pip->ip_len) - nhdr; tc = (struct tcphdr *)ip_next(pip); ptr = (u_short *) tc; /* Add up TCP header and data */ nbytes = ntcp; sum = 0; while (nbytes > 1) { sum += *ptr++; nbytes -= 2; } if (nbytes == 1) { oddbyte = 0; ((u_char *) & oddbyte)[0] = *(u_char *) ptr; ((u_char *) & oddbyte)[1] = 0; sum += oddbyte; } /* "Pseudo-header" data */ ptr = (void *)&pip->ip_dst; sum += *ptr++; sum += *ptr; ptr = (void *)&pip->ip_src; sum += *ptr++; sum += *ptr; sum += htons((u_short) ntcp); sum += htons((u_short) pip->ip_p); /* Roll over carry bits */ sum = (sum >> 16) + (sum & 0xffff); sum += (sum >> 16); /* Return checksum */ return ((u_short) ~ sum); } #endif /* not _KERNEL */ void DifferentialChecksum(u_short * cksum, void *newp, void *oldp, int n) { int i; int accumulate; u_short *new = newp; u_short *old = oldp; accumulate = *cksum; for (i = 0; i < n; i++) { accumulate -= *new++; accumulate += *old++; } if (accumulate < 0) { accumulate = -accumulate; accumulate = (accumulate >> 16) + (accumulate & 0xffff); accumulate += accumulate >> 16; *cksum = (u_short) ~ accumulate; } else { accumulate = (accumulate >> 16) + (accumulate & 0xffff); accumulate += accumulate >> 16; *cksum = (u_short) accumulate; } }