1706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh/*- 2706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * Copyright (c) 2000 Ruslan Ermilov and Brian Somers <brian@Awfulhak.org> 3706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * All rights reserved. 4706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * 5706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * Redistribution and use in source and binary forms, with or without 6706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * modification, are permitted provided that the following conditions 7706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * are met: 8706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * 1. Redistributions of source code must retain the above copyright 9706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * notice, this list of conditions and the following disclaimer. 10706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * 2. Redistributions in binary form must reproduce the above copyright 11706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * notice, this list of conditions and the following disclaimer in the 12706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * documentation and/or other materials provided with the distribution. 13706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * 14706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * SUCH DAMAGE. 25706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * 26706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * $FreeBSD: src/usr.sbin/ppp/tcpmss.c,v 1.8.26.1 2010/12/21 17:10:29 kensmith Exp $ 27706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh */ 28706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 29706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <sys/param.h> 30706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 31706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <sys/socket.h> 32706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <net/route.h> 33706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <netinet/in_systm.h> 34706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <netinet/in.h> 35706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <netinet/ip.h> 36706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <netinet/tcp.h> 37706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <sys/un.h> 38706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 39706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include <termios.h> 40706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 41706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "layer.h" 42706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "defs.h" 43706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "log.h" 44706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "timer.h" 45706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "fsm.h" 46706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "mbuf.h" 47706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "throughput.h" 48706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "lqr.h" 49706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "hdlc.h" 50706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "lcp.h" 51706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "ccp.h" 52706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "link.h" 53706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "iplist.h" 54706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "slcompress.h" 55706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "ncpaddr.h" 56706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "ipcp.h" 57706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "filter.h" 58706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "descriptor.h" 59706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "mp.h" 60706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "iface.h" 61706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#ifndef NORADIUS 62706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "radius.h" 63706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#endif 64706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "ipv6cp.h" 65706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "ncp.h" 66706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#include "bundle.h" 67706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 68706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 69706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh/*- 70706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * We are in a liberal position about MSS 71706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * (RFC 879, section 7). 72706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh */ 73706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#define MAXMSS(mtu) ((mtu) - sizeof(struct ip) - sizeof(struct tcphdr) - 12) 74706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 75706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 76706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh/*- 77706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * The following macro is used to update an 78706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * internet checksum. "acc" is a 32-bit 79706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * accumulation of all the changes to the 80706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * checksum (adding in old 16-bit words and 81706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * subtracting out new words), and "cksum" 82706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * is the checksum value to be updated. 83706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh */ 84706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh#define ADJUST_CHECKSUM(acc, cksum) { \ 85706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh acc += cksum; \ 86706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (acc < 0) { \ 87706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh acc = -acc; \ 88706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh acc = (acc >> 16) + (acc & 0xffff); \ 89706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh acc += acc >> 16; \ 90706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh cksum = (u_short) ~acc; \ 91706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh } else { \ 92706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh acc = (acc >> 16) + (acc & 0xffff); \ 93706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh acc += acc >> 16; \ 94706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh cksum = (u_short) acc; \ 95706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh } \ 96706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh} 97706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 98706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yehstatic void 99706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi YehMSSFixup(struct tcphdr *tc, size_t pktlen, u_int16_t maxmss) 100706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh{ 101706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh size_t hlen, olen, optlen; 102706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh u_char *opt; 103706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh u_int16_t *mss; 104706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh int accumulate; 105706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 106706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh hlen = tc->th_off << 2; 107706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 108706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh /* Invalid header length or header without options. */ 109706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (hlen <= sizeof(struct tcphdr) || hlen > pktlen) 110706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh return; 111706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 112706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh /* MSS option only allowed within SYN packets. */ 113706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (!(tc->th_flags & TH_SYN)) 114706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh return; 115706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 116706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh for (olen = hlen - sizeof(struct tcphdr), opt = (u_char *)(tc + 1); 117706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh olen > 0; olen -= optlen, opt += optlen) { 118706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (*opt == TCPOPT_EOL) 119706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh break; 120706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh else if (*opt == TCPOPT_NOP) 121706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh optlen = 1; 122706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh else { 123706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh optlen = *(opt + 1); 124706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (optlen <= 0 || optlen > olen) 125706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh break; 126706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (*opt == TCPOPT_MAXSEG) { 127706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (optlen != TCPOLEN_MAXSEG) 128706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh continue; 129706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh mss = (u_int16_t *)(opt + 2); 130706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (ntohs(*mss) > maxmss) { 131706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh log_Printf(LogDEBUG, "MSS: %u -> %u\n", 132706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh ntohs(*mss), maxmss); 133706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh accumulate = *mss; 134706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh *mss = htons(maxmss); 135706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh accumulate -= *mss; 136706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh ADJUST_CHECKSUM(accumulate, tc->th_sum); 137706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh } 138706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh } 139706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh } 140706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh } 141706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh} 142706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 143706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yehstatic struct mbuf * 144706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yehtcpmss_Check(struct bundle *bundle, struct mbuf *bp) 145706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh{ 146706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh struct ip *pip; 147706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh size_t hlen, plen; 148706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 149706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (!Enabled(bundle, OPT_TCPMSSFIXUP)) 150706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh return bp; 151706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 152706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh bp = m_pullup(bp); 153706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh plen = m_length(bp); 154706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh pip = (struct ip *)MBUF_CTOP(bp); 155706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh hlen = pip->ip_hl << 2; 156706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 157706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh /* 158706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * Check for MSS option only for TCP packets with zero fragment offsets 159706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh * and correct total and header lengths. 160706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh */ 161706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh if (pip->ip_p == IPPROTO_TCP && (ntohs(pip->ip_off) & IP_OFFMASK) == 0 && 162706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh ntohs(pip->ip_len) == plen && hlen <= plen && 163706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh plen >= sizeof(struct tcphdr) + hlen) 164706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh MSSFixup((struct tcphdr *)(MBUF_CTOP(bp) + hlen), plen - hlen, 165706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh MAXMSS(bundle->iface->mtu)); 166706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 167706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh return bp; 168706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh} 169706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 170706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yehstatic struct mbuf * 171706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yehtcpmss_LayerPush(struct bundle *bundle, struct link *l __unused, 172706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh struct mbuf *bp, int pri __unused, u_short *proto __unused) 173706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh{ 174706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh return tcpmss_Check(bundle, bp); 175706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh} 176706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 177706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yehstatic struct mbuf * 178706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yehtcpmss_LayerPull(struct bundle *bundle, struct link *l __unused, 179706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh struct mbuf *bp, u_short *proto __unused) 180706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh{ 181706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh return tcpmss_Check(bundle, bp); 182706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh} 183706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh 184706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yehstruct layer tcpmsslayer = 185706e567fc5ff6b79738a5f470e5aa7b2cae76459Chia-chi Yeh { LAYER_PROTO, "tcpmss", tcpmss_LayerPush, tcpmss_LayerPull }; 186