slcompress.c revision 30715
16059Samurai/* 26059Samurai * Routines to compress and uncompess tcp packets (for transmission 36059Samurai * over low speed serial lines. 46059Samurai * 56059Samurai * Copyright (c) 1989 Regents of the University of California. 66059Samurai * All rights reserved. 76059Samurai * 86059Samurai * Redistribution and use in source and binary forms are permitted 96059Samurai * provided that the above copyright notice and this paragraph are 106059Samurai * duplicated in all such forms and that any documentation, 116059Samurai * advertising materials, and other materials related to such 126059Samurai * distribution and use acknowledge that the software was developed 136059Samurai * by the University of California, Berkeley. The name of the 146059Samurai * University may not be used to endorse or promote products derived 156059Samurai * from this software without specific prior written permission. 166059Samurai * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 176059Samurai * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 186059Samurai * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 196059Samurai * 2030715Sbrian * $Id: slcompress.c,v 1.12 1997/10/12 21:43:55 brian Exp $ 218857Srgrimes * 226059Samurai * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989: 236059Samurai * - Initial distribution. 246059Samurai */ 2528679Sbrian 2630715Sbrian#include <sys/param.h> 276059Samurai#include <netinet/in_systm.h> 286059Samurai#include <netinet/in.h> 296059Samurai#include <netinet/tcp.h> 306059Samurai#include <netinet/ip.h> 3130715Sbrian 3230715Sbrian#include <stdio.h> 3330715Sbrian#include <string.h> 3430715Sbrian 3530715Sbrian#include "mbuf.h" 3630715Sbrian#include "log.h" 3730715Sbrian#include "defs.h" 386059Samurai#include "slcompress.h" 3926516Sbrian#include "loadalias.h" 4030715Sbrian#include "command.h" 4126516Sbrian#include "vars.h" 426059Samurai 4330715Sbrianstatic struct slstat { 4430715Sbrian int sls_packets; /* outbound packets */ 4530715Sbrian int sls_compressed; /* outbound compressed packets */ 4630715Sbrian int sls_searches; /* searches for connection state */ 4730715Sbrian int sls_misses; /* times couldn't find conn. state */ 4830715Sbrian int sls_uncompressedin; /* inbound uncompressed packets */ 4930715Sbrian int sls_compressedin; /* inbound compressed packets */ 5030715Sbrian int sls_errorin; /* inbound unknown type packets */ 5130715Sbrian int sls_tossed; /* inbound packets tossed because of error */ 5230715Sbrian} slstat; 536059Samurai 546059Samurai#define INCR(counter) slstat.counter++; 556059Samurai 566059Samuraivoid 5730187Sbriansl_compress_init(struct slcompress * comp, int max_state) 586059Samurai{ 5928679Sbrian register u_int i; 6028679Sbrian register struct cstate *tstate = comp->tstate; 616059Samurai 6230715Sbrian memset(comp, '\0', sizeof(*comp)); 6330187Sbrian for (i = max_state; i > 0; --i) { 6428679Sbrian tstate[i].cs_id = i; 6528679Sbrian tstate[i].cs_next = &tstate[i - 1]; 6628679Sbrian } 6730187Sbrian tstate[0].cs_next = &tstate[max_state]; 6828679Sbrian tstate[0].cs_id = 0; 6928679Sbrian comp->last_cs = &tstate[0]; 7028679Sbrian comp->last_recv = 255; 7128679Sbrian comp->last_xmit = 255; 7228679Sbrian comp->flags = SLF_TOSS; 736059Samurai} 746059Samurai 756059Samurai 766059Samurai/* ENCODE encodes a number that is known to be non-zero. ENCODEZ 776059Samurai * checks for zero (since zero has to be encoded in the long, 3 byte 786059Samurai * form). 796059Samurai */ 806059Samurai#define ENCODE(n) { \ 816059Samurai if ((u_short)(n) >= 256) { \ 826059Samurai *cp++ = 0; \ 836059Samurai cp[1] = (n); \ 846059Samurai cp[0] = (n) >> 8; \ 856059Samurai cp += 2; \ 866059Samurai } else { \ 876059Samurai *cp++ = (n); \ 886059Samurai } \ 896059Samurai} 906059Samurai#define ENCODEZ(n) { \ 916059Samurai if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \ 926059Samurai *cp++ = 0; \ 936059Samurai cp[1] = (n); \ 946059Samurai cp[0] = (n) >> 8; \ 956059Samurai cp += 2; \ 966059Samurai } else { \ 976059Samurai *cp++ = (n); \ 986059Samurai } \ 996059Samurai} 1006059Samurai 1016059Samurai#define DECODEL(f) { \ 1026059Samurai if (*cp == 0) {\ 1036059Samurai (f) = htonl(ntohl(f) + ((cp[1] << 8) | cp[2])); \ 1046059Samurai cp += 3; \ 1056059Samurai } else { \ 1066059Samurai (f) = htonl(ntohl(f) + (u_long)*cp++); \ 1076059Samurai } \ 1086059Samurai} 1096059Samurai 1106059Samurai#define DECODES(f) { \ 1116059Samurai if (*cp == 0) {\ 1126059Samurai (f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \ 1136059Samurai cp += 3; \ 1146059Samurai } else { \ 1156059Samurai (f) = htons(ntohs(f) + (u_long)*cp++); \ 1166059Samurai } \ 1176059Samurai} 1186059Samurai 1196059Samurai#define DECODEU(f) { \ 1206059Samurai if (*cp == 0) {\ 1216059Samurai (f) = htons((cp[1] << 8) | cp[2]); \ 1226059Samurai cp += 3; \ 1236059Samurai } else { \ 1246059Samurai (f) = htons((u_long)*cp++); \ 1256059Samurai } \ 1266059Samurai} 1276059Samurai 1286059Samurai 1296059Samuraiu_char 13028679Sbriansl_compress_tcp(struct mbuf * m, 13128679Sbrian struct ip * ip, 13228679Sbrian struct slcompress * comp, 13328679Sbrian int compress_cid) 1346059Samurai{ 13528679Sbrian register struct cstate *cs = comp->last_cs->cs_next; 13628679Sbrian register u_int hlen = ip->ip_hl; 13728679Sbrian register struct tcphdr *oth; 13828679Sbrian register struct tcphdr *th; 13928679Sbrian register u_int deltaS, deltaA; 14028679Sbrian register u_int changes = 0; 14128679Sbrian u_char new_seq[16]; 14228679Sbrian register u_char *cp = new_seq; 1436059Samurai 14428679Sbrian /* 14528679Sbrian * Bail if this is an IP fragment or if the TCP packet isn't `compressible' 14628679Sbrian * (i.e., ACK isn't set or some other control bit is set). (We assume that 14728679Sbrian * the caller has already made sure the packet is IP proto TCP). 14828679Sbrian */ 14928679Sbrian if ((ip->ip_off & htons(0x3fff)) || m->cnt < 40) { 15028679Sbrian LogPrintf(LogDEBUG, "??? 1 ip_off = %x, cnt = %d\n", 15128679Sbrian ip->ip_off, m->cnt); 15228679Sbrian LogDumpBp(LogDEBUG, "", m); 15328679Sbrian return (TYPE_IP); 15428679Sbrian } 15528679Sbrian th = (struct tcphdr *) & ((int *) ip)[hlen]; 15628679Sbrian if ((th->th_flags & (TH_SYN | TH_FIN | TH_RST | TH_ACK)) != TH_ACK) { 15728679Sbrian LogPrintf(LogDEBUG, "??? 2 th_flags = %x\n", th->th_flags); 15828679Sbrian LogDumpBp(LogDEBUG, "", m); 15928679Sbrian return (TYPE_IP); 16028679Sbrian } 1616059Samurai 16228679Sbrian /* 16328679Sbrian * Packet is compressible -- we're going to send either a COMPRESSED_TCP or 16428679Sbrian * UNCOMPRESSED_TCP packet. Either way we need to locate (or create) the 16528679Sbrian * connection state. Special case the most recently used connection since 16628679Sbrian * it's most likely to be used again & we don't have to do any reordering 16728679Sbrian * if it's used. 16828679Sbrian */ 16928679Sbrian INCR(sls_packets) 17028679Sbrian if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr || 17128679Sbrian ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr || 17228679Sbrian *(int *) th != ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl]) { 1736059Samurai 17428679Sbrian /* 17528679Sbrian * Wasn't the first -- search for it. 17628679Sbrian * 17728679Sbrian * States are kept in a circularly linked list with last_cs pointing to the 17828679Sbrian * end of the list. The list is kept in lru order by moving a state to 17928679Sbrian * the head of the list whenever it is referenced. Since the list is 18028679Sbrian * short and, empirically, the connection we want is almost always near 18128679Sbrian * the front, we locate states via linear search. If we don't find a 18228679Sbrian * state for the datagram, the oldest state is (re-)used. 18328679Sbrian */ 18428679Sbrian register struct cstate *lcs; 18528679Sbrian register struct cstate *lastcs = comp->last_cs; 1866059Samurai 18728679Sbrian do { 18828679Sbrian lcs = cs; 18928679Sbrian cs = cs->cs_next; 19028679Sbrian INCR(sls_searches) 19128679Sbrian if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr 19228679Sbrian && ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr 19328679Sbrian && *(int *) th == ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl]) 19428679Sbrian goto found; 19528679Sbrian } while (cs != lastcs); 1966059Samurai 19728679Sbrian /* 19828679Sbrian * Didn't find it -- re-use oldest cstate. Send an uncompressed packet 19928679Sbrian * that tells the other side what connection number we're using for this 20028679Sbrian * conversation. Note that since the state list is circular, the oldest 20128679Sbrian * state points to the newest and we only need to set last_cs to update 20228679Sbrian * the lru linkage. 20328679Sbrian */ 20428679Sbrian INCR(sls_misses) 20528679Sbrian comp->last_cs = lcs; 2066059Samurai#define THOFFSET(th) (th->th_off) 20728679Sbrian hlen += th->th_off; 20828679Sbrian hlen <<= 2; 20928679Sbrian if (hlen > m->cnt) 21028679Sbrian return (TYPE_IP); 21128679Sbrian goto uncompressed; 2126059Samurai 21328679Sbrianfound: 2146059Samurai 21528679Sbrian /* 21628679Sbrian * Found it -- move to the front on the connection list. 21728679Sbrian */ 21828679Sbrian if (cs == lastcs) 21928679Sbrian comp->last_cs = lcs; 22028679Sbrian else { 22128679Sbrian lcs->cs_next = cs->cs_next; 22228679Sbrian cs->cs_next = lastcs->cs_next; 22328679Sbrian lastcs->cs_next = cs; 22428679Sbrian } 22528679Sbrian } 2266059Samurai 22728679Sbrian /* 22828679Sbrian * Make sure that only what we expect to change changed. The first line of 22928679Sbrian * the `if' checks the IP protocol version, header length & type of 23028679Sbrian * service. The 2nd line checks the "Don't fragment" bit. The 3rd line 23128679Sbrian * checks the time-to-live and protocol (the protocol check is unnecessary 23228679Sbrian * but costless). The 4th line checks the TCP header length. The 5th line 23328679Sbrian * checks IP options, if any. The 6th line checks TCP options, if any. If 23428679Sbrian * any of these things are different between the previous & current 23528679Sbrian * datagram, we send the current datagram `uncompressed'. 23628679Sbrian */ 23728679Sbrian oth = (struct tcphdr *) & ((int *) &cs->cs_ip)[hlen]; 23828679Sbrian deltaS = hlen; 23928679Sbrian hlen += th->th_off; 24028679Sbrian hlen <<= 2; 24128679Sbrian if (hlen > m->cnt) 24228679Sbrian return (TYPE_IP); 2436059Samurai 24428679Sbrian if (((u_short *) ip)[0] != ((u_short *) & cs->cs_ip)[0] || 24528679Sbrian ((u_short *) ip)[3] != ((u_short *) & cs->cs_ip)[3] || 24628679Sbrian ((u_short *) ip)[4] != ((u_short *) & cs->cs_ip)[4] || 24728679Sbrian THOFFSET(th) != THOFFSET(oth) || 24828679Sbrian (deltaS > 5 && 24930715Sbrian memcmp(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) || 25028679Sbrian (THOFFSET(th) > 5 && 25130715Sbrian memcmp(th + 1, oth + 1, (THOFFSET(th) - 5) << 2))) { 25228679Sbrian goto uncompressed; 25328679Sbrian } 2546059Samurai 25528679Sbrian /* 25628679Sbrian * Figure out which of the changing fields changed. The receiver expects 25728679Sbrian * changes in the order: urgent, window, ack, seq (the order minimizes the 25828679Sbrian * number of temporaries needed in this section of code). 25928679Sbrian */ 26028679Sbrian if (th->th_flags & TH_URG) { 26128679Sbrian deltaS = ntohs(th->th_urp); 26228679Sbrian ENCODEZ(deltaS); 26328679Sbrian changes |= NEW_U; 26428679Sbrian } else if (th->th_urp != oth->th_urp) { 2656059Samurai 26628679Sbrian /* 26728679Sbrian * argh! URG not set but urp changed -- a sensible implementation should 26828679Sbrian * never do this but RFC793 doesn't prohibit the change so we have to 26928679Sbrian * deal with it. 27028679Sbrian */ 27128679Sbrian goto uncompressed; 27228679Sbrian } 27328679Sbrian deltaS = (u_short) (ntohs(th->th_win) - ntohs(oth->th_win)); 27428679Sbrian if (deltaS) { 27528679Sbrian ENCODE(deltaS); 27628679Sbrian changes |= NEW_W; 27728679Sbrian } 27828679Sbrian deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack); 27928679Sbrian if (deltaA) { 28028679Sbrian if (deltaA > 0xffff) { 28128679Sbrian goto uncompressed; 28228679Sbrian } 28328679Sbrian ENCODE(deltaA); 28428679Sbrian changes |= NEW_A; 28528679Sbrian } 28628679Sbrian deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq); 28728679Sbrian if (deltaS) { 28828679Sbrian if (deltaS > 0xffff) { 28928679Sbrian goto uncompressed; 29028679Sbrian } 29128679Sbrian ENCODE(deltaS); 29228679Sbrian changes |= NEW_S; 29328679Sbrian } 29428679Sbrian switch (changes) { 2956059Samurai 29628679Sbrian case 0: 2976059Samurai 29828679Sbrian /* 29928679Sbrian * Nothing changed. If this packet contains data and the last one didn't, 30028679Sbrian * this is probably a data packet following an ack (normal on an 30128679Sbrian * interactive connection) and we send it compressed. Otherwise it's 30228679Sbrian * probably a retransmit, retransmitted ack or window probe. Send it 30328679Sbrian * uncompressed in case the other side missed the compressed version. 30428679Sbrian */ 30528679Sbrian if (ip->ip_len != cs->cs_ip.ip_len && 30628679Sbrian ntohs(cs->cs_ip.ip_len) == hlen) 30728679Sbrian break; 3086059Samurai 30928679Sbrian /* (fall through) */ 3106059Samurai 31128679Sbrian case SPECIAL_I: 31228679Sbrian case SPECIAL_D: 3136059Samurai 31428679Sbrian /* 31528679Sbrian * actual changes match one of our special case encodings -- send packet 31628679Sbrian * uncompressed. 31728679Sbrian */ 31828679Sbrian goto uncompressed; 3196059Samurai 32028679Sbrian case NEW_S | NEW_A: 32128679Sbrian if (deltaS == deltaA && 32228679Sbrian deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { 32328679Sbrian /* special case for echoed terminal traffic */ 32428679Sbrian changes = SPECIAL_I; 32528679Sbrian cp = new_seq; 32628679Sbrian } 32728679Sbrian break; 3286059Samurai 32928679Sbrian case NEW_S: 33028679Sbrian if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) { 33128679Sbrian /* special case for data xfer */ 33228679Sbrian changes = SPECIAL_D; 33328679Sbrian cp = new_seq; 33428679Sbrian } 33528679Sbrian break; 33628679Sbrian } 3376059Samurai 33828679Sbrian deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id); 33928679Sbrian if (deltaS != 1) { 34028679Sbrian ENCODEZ(deltaS); 34128679Sbrian changes |= NEW_I; 34228679Sbrian } 34328679Sbrian if (th->th_flags & TH_PUSH) 34428679Sbrian changes |= TCP_PUSH_BIT; 3456059Samurai 34628679Sbrian /* 34728679Sbrian * Grab the cksum before we overwrite it below. Then update our state with 34828679Sbrian * this packet's header. 34928679Sbrian */ 35028679Sbrian deltaA = ntohs(th->th_sum); 35130715Sbrian memcpy(&cs->cs_ip, ip, hlen); 3526059Samurai 35328679Sbrian /* 35428679Sbrian * We want to use the original packet as our compressed packet. (cp - 35528679Sbrian * new_seq) is the number of bytes we need for compressed sequence numbers. 35628679Sbrian * In addition we need one byte for the change mask, one for the connection 35728679Sbrian * id and two for the tcp checksum. So, (cp - new_seq) + 4 bytes of header 35828679Sbrian * are needed. hlen is how many bytes of the original packet to toss so 35928679Sbrian * subtract the two to get the new packet size. 36028679Sbrian */ 36128679Sbrian deltaS = cp - new_seq; 36228679Sbrian cp = (u_char *) ip; 36328679Sbrian 36428679Sbrian /* 36528679Sbrian * Since fastq traffic can jump ahead of the background traffic, we don't 36628679Sbrian * know what order packets will go on the line. In this case, we always 36728679Sbrian * send a "new" connection id so the receiver state stays synchronized. 36828679Sbrian */ 36930187Sbrian if (comp->last_xmit == cs->cs_id && compress_cid) { 37028679Sbrian hlen -= deltaS + 3; 37128679Sbrian cp += hlen; 37228679Sbrian *cp++ = changes; 37330187Sbrian } else { 37428679Sbrian comp->last_xmit = cs->cs_id; 37528679Sbrian hlen -= deltaS + 4; 37628679Sbrian cp += hlen; 37728679Sbrian *cp++ = changes | NEW_C; 37828679Sbrian *cp++ = cs->cs_id; 37928679Sbrian } 38028679Sbrian m->cnt -= hlen; 38128679Sbrian m->offset += hlen; 38228679Sbrian *cp++ = deltaA >> 8; 38328679Sbrian *cp++ = deltaA; 38430715Sbrian memcpy(cp, new_seq, deltaS); 38528679Sbrian INCR(sls_compressed) 38628679Sbrian return (TYPE_COMPRESSED_TCP); 3876059Samurai 38828679Sbrian /* 38928679Sbrian * Update connection state cs & send uncompressed packet ('uncompressed' 39028679Sbrian * means a regular ip/tcp packet but with the 'conversation id' we hope to 39128679Sbrian * use on future compressed packets in the protocol field). 39228679Sbrian */ 3936059Samuraiuncompressed: 39430715Sbrian memcpy(&cs->cs_ip, ip, hlen); 39528679Sbrian ip->ip_p = cs->cs_id; 39628679Sbrian comp->last_xmit = cs->cs_id; 39728679Sbrian return (TYPE_UNCOMPRESSED_TCP); 3986059Samurai} 3996059Samurai 4006059Samurai 4016059Samuraiint 40228679Sbriansl_uncompress_tcp(u_char ** bufp, 40328679Sbrian int len, 40428679Sbrian u_int type, 40528679Sbrian struct slcompress * comp) 4066059Samurai{ 40728679Sbrian register u_char *cp; 40828679Sbrian register u_int hlen, changes; 40928679Sbrian register struct tcphdr *th; 41028679Sbrian register struct cstate *cs; 41128679Sbrian register struct ip *ip; 4126059Samurai 41328679Sbrian switch (type) { 4146059Samurai 41528679Sbrian case TYPE_UNCOMPRESSED_TCP: 41628679Sbrian ip = (struct ip *) * bufp; 41728679Sbrian if (ip->ip_p >= MAX_STATES) 41828679Sbrian goto bad; 41928679Sbrian cs = &comp->rstate[comp->last_recv = ip->ip_p]; 42028679Sbrian comp->flags &= ~SLF_TOSS; 42128679Sbrian ip->ip_p = IPPROTO_TCP; 4226059Samurai 42328679Sbrian /* 42428679Sbrian * Calculate the size of the TCP/IP header and make sure that we don't 42528679Sbrian * overflow the space we have available for it. 42628679Sbrian */ 42728679Sbrian hlen = ip->ip_hl << 2; 42828679Sbrian if (hlen + sizeof(struct tcphdr) > len) 42928679Sbrian goto bad; 43028679Sbrian th = (struct tcphdr *) & ((char *) ip)[hlen]; 43128679Sbrian hlen += THOFFSET(th) << 2; 43228679Sbrian if (hlen > MAX_HDR) 43328679Sbrian goto bad; 43430715Sbrian memcpy(&cs->cs_ip, ip, hlen); 43530357Sbrian cs->cs_ip.ip_sum = 0; 43628679Sbrian cs->cs_hlen = hlen; 43728679Sbrian INCR(sls_uncompressedin) 43828679Sbrian return (len); 4396059Samurai 44028679Sbrian default: 44128679Sbrian goto bad; 4426059Samurai 44328679Sbrian case TYPE_COMPRESSED_TCP: 44428679Sbrian break; 44528679Sbrian } 44628679Sbrian /* We've got a compressed packet. */ 44728679Sbrian INCR(sls_compressedin) 44828679Sbrian cp = *bufp; 44928679Sbrian changes = *cp++; 45028679Sbrian LogPrintf(LogDEBUG, "compressed: changes = %02x\n", changes); 45128679Sbrian if (changes & NEW_C) { 4526059Samurai 45328679Sbrian /* 45428679Sbrian * Make sure the state index is in range, then grab the state. If we have 45528679Sbrian * a good state index, clear the 'discard' flag. 45628679Sbrian */ 45728679Sbrian if (*cp >= MAX_STATES || comp->last_recv == 255) 45828679Sbrian goto bad; 4596059Samurai 46028679Sbrian comp->flags &= ~SLF_TOSS; 46128679Sbrian comp->last_recv = *cp++; 46228679Sbrian } else { 4636059Samurai 46428679Sbrian /* 46528679Sbrian * this packet has an implicit state index. If we've had a line error 46628679Sbrian * since the last time we got an explicit state index, we have to toss 46728679Sbrian * the packet. 46828679Sbrian */ 46928679Sbrian if (comp->flags & SLF_TOSS) { 47028679Sbrian INCR(sls_tossed) 47128679Sbrian return (0); 47228679Sbrian } 47328679Sbrian } 47428679Sbrian cs = &comp->rstate[comp->last_recv]; 47528679Sbrian hlen = cs->cs_ip.ip_hl << 2; 47628679Sbrian th = (struct tcphdr *) & ((u_char *) & cs->cs_ip)[hlen]; 47728679Sbrian th->th_sum = htons((*cp << 8) | cp[1]); 47828679Sbrian cp += 2; 47928679Sbrian if (changes & TCP_PUSH_BIT) 48028679Sbrian th->th_flags |= TH_PUSH; 48128679Sbrian else 48228679Sbrian th->th_flags &= ~TH_PUSH; 48328679Sbrian 48428679Sbrian switch (changes & SPECIALS_MASK) { 48528679Sbrian case SPECIAL_I: 48628679Sbrian { 48728679Sbrian register u_int i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen; 48828679Sbrian 48928679Sbrian th->th_ack = htonl(ntohl(th->th_ack) + i); 49028679Sbrian th->th_seq = htonl(ntohl(th->th_seq) + i); 49128679Sbrian } 49228679Sbrian break; 49328679Sbrian 49428679Sbrian case SPECIAL_D: 49528679Sbrian th->th_seq = htonl(ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len) 49628679Sbrian - cs->cs_hlen); 49728679Sbrian break; 49828679Sbrian 49928679Sbrian default: 50028679Sbrian if (changes & NEW_U) { 50128679Sbrian th->th_flags |= TH_URG; 50228679Sbrian DECODEU(th->th_urp) 50328679Sbrian } else 50428679Sbrian th->th_flags &= ~TH_URG; 50528679Sbrian if (changes & NEW_W) 50628679Sbrian DECODES(th->th_win) 50728679Sbrian if (changes & NEW_A) 50828679Sbrian DECODEL(th->th_ack) 50928679Sbrian if (changes & NEW_S) { 51028679Sbrian LogPrintf(LogDEBUG, "NEW_S: %02x, %02x, %02x\n", 51128679Sbrian *cp, cp[1], cp[2]); 51228679Sbrian DECODEL(th->th_seq) 5136059Samurai } 51428679Sbrian break; 51528679Sbrian } 51628679Sbrian if (changes & NEW_I) { 51728679Sbrian DECODES(cs->cs_ip.ip_id) 51828679Sbrian } else 51928679Sbrian cs->cs_ip.ip_id = htons(ntohs(cs->cs_ip.ip_id) + 1); 5206059Samurai 52128679Sbrian LogPrintf(LogDEBUG, "Uncompress: id = %04x, seq = %08x\n", 52228679Sbrian cs->cs_ip.ip_id, ntohl(th->th_seq)); 52326516Sbrian 52428679Sbrian /* 52528679Sbrian * At this point, cp points to the first byte of data in the packet. If 52628679Sbrian * we're not aligned on a 4-byte boundary, copy the data down so the ip & 52728679Sbrian * tcp headers will be aligned. Then back up cp by the tcp/ip header 52828679Sbrian * length to make room for the reconstructed header (we assume the packet 52928679Sbrian * we were handed has enough space to prepend 128 bytes of header). Adjust 53028679Sbrian * the length to account for the new header & fill in the IP total length. 53128679Sbrian */ 53228679Sbrian len -= (cp - *bufp); 53328679Sbrian if (len < 0) 5346059Samurai 53528679Sbrian /* 53628679Sbrian * we must have dropped some characters (crc should detect this but the 53728679Sbrian * old slip framing won't) 53828679Sbrian */ 53928679Sbrian goto bad; 54028679Sbrian 5416059Samurai#ifdef notdef 54228679Sbrian if ((int) cp & 3) { 54328679Sbrian if (len > 0) 54430715Sbrian (void) bcopy(cp, (caddr_t) ((int) cp & ~3), len); 54528679Sbrian cp = (u_char *) ((int) cp & ~3); 54628679Sbrian } 5476059Samurai#endif 5486059Samurai 54928679Sbrian cp -= cs->cs_hlen; 55028679Sbrian len += cs->cs_hlen; 55128679Sbrian cs->cs_ip.ip_len = htons(len); 55230715Sbrian memcpy(cp, &cs->cs_ip, cs->cs_hlen); 55328679Sbrian *bufp = cp; 5546059Samurai 55528679Sbrian /* recompute the ip header checksum */ 55628679Sbrian { 55728679Sbrian register u_short *bp = (u_short *) cp; 55828679Sbrian 55928679Sbrian for (changes = 0; hlen > 0; hlen -= 2) 56028679Sbrian changes += *bp++; 56128679Sbrian changes = (changes & 0xffff) + (changes >> 16); 56228679Sbrian changes = (changes & 0xffff) + (changes >> 16); 56328679Sbrian ((struct ip *) cp)->ip_sum = ~changes; 56428679Sbrian } 56528679Sbrian return (len); 5666059Samuraibad: 56728679Sbrian comp->flags |= SLF_TOSS; 56828679Sbrian INCR(sls_errorin) 56928679Sbrian return (0); 5706059Samurai} 5716059Samurai 5726059Samuraiint 5736059SamuraiReportCompress() 5746059Samurai{ 57526516Sbrian if (!VarTerm) 57626516Sbrian return 1; 57726516Sbrian 57826516Sbrian fprintf(VarTerm, "Out: %d (compress) / %d (total)", 57928679Sbrian slstat.sls_compressed, slstat.sls_packets); 58026516Sbrian fprintf(VarTerm, " %d (miss) / %d (search)\n", 58128679Sbrian slstat.sls_misses, slstat.sls_searches); 58226516Sbrian fprintf(VarTerm, "In: %d (compress), %d (uncompress)", 58328679Sbrian slstat.sls_compressedin, slstat.sls_uncompressedin); 58426516Sbrian fprintf(VarTerm, " %d (error), %d (tossed)\n", 58528679Sbrian slstat.sls_errorin, slstat.sls_tossed); 58626516Sbrian return 0; 5876059Samurai} 588