+++ /dev/null
-/*
- * Routines to compress and uncompess tcp packets (for transmission
- * over low speed serial lines.
- *
- * Copyright (c) 1989 Regents of the University of California.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms are permitted
- * provided that the above copyright notice and this paragraph are
- * duplicated in all such forms and that any documentation,
- * advertising materials, and other materials related to such
- * distribution and use acknowledge that the software was developed
- * by the University of California, Berkeley. The name of the
- * University may not be used to endorse or promote products derived
- * from this software without specific prior written permission.
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
- * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
- *
- * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
- * Initial distribution.
- *
- * Modified June 1993 by Paul Mackerras, paulus@cs.anu.edu.au,
- * so that the entire packet being decompressed doesn't have
- * to be in contiguous memory (just the compressed header).
- *
- * Modified March 1998 by Guy Lancaster, glanca@gesn.com,
- * for a 16 bit processor.
- */
-
-#include "lwip/opt.h"
-
-#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
-
-#include "ppp_impl.h"
-#include "pppdebug.h"
-
-#include "vj.h"
-
-#include <string.h>
-
-#if VJ_SUPPORT
-
-#if LINK_STATS
-#define INCR(counter) ++comp->stats.counter
-#else
-#define INCR(counter)
-#endif
-
-void
-vj_compress_init(struct vjcompress *comp)
-{
- register u_char i;
- register struct cstate *tstate = comp->tstate;
-
-#if MAX_SLOTS == 0
- memset((char *)comp, 0, sizeof(*comp));
-#endif
- comp->maxSlotIndex = MAX_SLOTS - 1;
- comp->compressSlot = 0; /* Disable slot ID compression by default. */
- for (i = MAX_SLOTS - 1; i > 0; --i) {
- tstate[i].cs_id = i;
- tstate[i].cs_next = &tstate[i - 1];
- }
- tstate[0].cs_next = &tstate[MAX_SLOTS - 1];
- tstate[0].cs_id = 0;
- comp->last_cs = &tstate[0];
- comp->last_recv = 255;
- comp->last_xmit = 255;
- comp->flags = VJF_TOSS;
-}
-
-
-/* ENCODE encodes a number that is known to be non-zero. ENCODEZ
- * checks for zero (since zero has to be encoded in the long, 3 byte
- * form).
- */
-#define ENCODE(n) { \
- if ((u_short)(n) >= 256) { \
- *cp++ = 0; \
- cp[1] = (u_char)(n); \
- cp[0] = (u_char)((n) >> 8); \
- cp += 2; \
- } else { \
- *cp++ = (u_char)(n); \
- } \
-}
-#define ENCODEZ(n) { \
- if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \
- *cp++ = 0; \
- cp[1] = (u_char)(n); \
- cp[0] = (u_char)((n) >> 8); \
- cp += 2; \
- } else { \
- *cp++ = (u_char)(n); \
- } \
-}
-
-#define DECODEL(f) { \
- if (*cp == 0) {\
- u32_t tmp = ntohl(f) + ((cp[1] << 8) | cp[2]); \
- (f) = htonl(tmp); \
- cp += 3; \
- } else { \
- u32_t tmp = ntohl(f) + (u32_t)*cp++; \
- (f) = htonl(tmp); \
- } \
-}
-
-#define DECODES(f) { \
- if (*cp == 0) {\
- u_short tmp = ntohs(f) + (((u_short)cp[1] << 8) | cp[2]); \
- (f) = htons(tmp); \
- cp += 3; \
- } else { \
- u_short tmp = ntohs(f) + (u_short)*cp++; \
- (f) = htons(tmp); \
- } \
-}
-
-#define DECODEU(f) { \
- if (*cp == 0) {\
- (f) = htons(((u_short)cp[1] << 8) | cp[2]); \
- cp += 3; \
- } else { \
- (f) = htons((u_short)*cp++); \
- } \
-}
-
-/*
- * vj_compress_tcp - Attempt to do Van Jacobson header compression on a
- * packet. This assumes that nb and comp are not null and that the first
- * buffer of the chain contains a valid IP header.
- * Return the VJ type code indicating whether or not the packet was
- * compressed.
- */
-u_int
-vj_compress_tcp(struct vjcompress *comp, struct pbuf *pb)
-{
- register struct ip_hdr *ip = (struct ip_hdr *)pb->payload;
- register struct cstate *cs = comp->last_cs->cs_next;
- register u_short hlen = IPH_HL(ip);
- register struct tcp_hdr *oth;
- register struct tcp_hdr *th;
- register u_short deltaS, deltaA;
- register u_long deltaL;
- register u_int changes = 0;
- u_char new_seq[16];
- register u_char *cp = new_seq;
-
- /*
- * Check that the packet is IP proto TCP.
- */
- if (IPH_PROTO(ip) != IP_PROTO_TCP) {
- return (TYPE_IP);
- }
-
- /*
- * Bail if this is an IP fragment or if the TCP packet isn't
- * `compressible' (i.e., ACK isn't set or some other control bit is
- * set).
- */
- if ((IPH_OFFSET(ip) & PP_HTONS(0x3fff)) || pb->tot_len < 40) {
- return (TYPE_IP);
- }
- th = (struct tcp_hdr *)&((long *)ip)[hlen];
- if ((TCPH_FLAGS(th) & (TCP_SYN|TCP_FIN|TCP_RST|TCP_ACK)) != TCP_ACK) {
- return (TYPE_IP);
- }
- /*
- * Packet is compressible -- we're going to send either a
- * COMPRESSED_TCP or UNCOMPRESSED_TCP packet. Either way we need
- * to locate (or create) the connection state. Special case the
- * most recently used connection since it's most likely to be used
- * again & we don't have to do any reordering if it's used.
- */
- INCR(vjs_packets);
- if (!ip_addr_cmp(&ip->src, &cs->cs_ip.src)
- || !ip_addr_cmp(&ip->dest, &cs->cs_ip.dest)
- || *(long *)th != ((long *)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]) {
- /*
- * Wasn't the first -- search for it.
- *
- * States are kept in a circularly linked list with
- * last_cs pointing to the end of the list. The
- * list is kept in lru order by moving a state to the
- * head of the list whenever it is referenced. Since
- * the list is short and, empirically, the connection
- * we want is almost always near the front, we locate
- * states via linear search. If we don't find a state
- * for the datagram, the oldest state is (re-)used.
- */
- register struct cstate *lcs;
- register struct cstate *lastcs = comp->last_cs;
-
- do {
- lcs = cs; cs = cs->cs_next;
- INCR(vjs_searches);
- if (ip_addr_cmp(&ip->src, &cs->cs_ip.src)
- && ip_addr_cmp(&ip->dest, &cs->cs_ip.dest)
- && *(long *)th == ((long *)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]) {
- goto found;
- }
- } while (cs != lastcs);
-
- /*
- * Didn't find it -- re-use oldest cstate. Send an
- * uncompressed packet that tells the other side what
- * connection number we're using for this conversation.
- * Note that since the state list is circular, the oldest
- * state points to the newest and we only need to set
- * last_cs to update the lru linkage.
- */
- INCR(vjs_misses);
- comp->last_cs = lcs;
- hlen += TCPH_HDRLEN(th);
- hlen <<= 2;
- /* Check that the IP/TCP headers are contained in the first buffer. */
- if (hlen > pb->len) {
- return (TYPE_IP);
- }
- goto uncompressed;
-
- found:
- /*
- * Found it -- move to the front on the connection list.
- */
- if (cs == lastcs) {
- comp->last_cs = lcs;
- } else {
- lcs->cs_next = cs->cs_next;
- cs->cs_next = lastcs->cs_next;
- lastcs->cs_next = cs;
- }
- }
-
- oth = (struct tcp_hdr *)&((long *)&cs->cs_ip)[hlen];
- deltaS = hlen;
- hlen += TCPH_HDRLEN(th);
- hlen <<= 2;
- /* Check that the IP/TCP headers are contained in the first buffer. */
- if (hlen > pb->len) {
- PPPDEBUG(LOG_INFO, ("vj_compress_tcp: header len %d spans buffers\n", hlen));
- return (TYPE_IP);
- }
-
- /*
- * Make sure that only what we expect to change changed. The first
- * line of the `if' checks the IP protocol version, header length &
- * type of service. The 2nd line checks the "Don't fragment" bit.
- * The 3rd line checks the time-to-live and protocol (the protocol
- * check is unnecessary but costless). The 4th line checks the TCP
- * header length. The 5th line checks IP options, if any. The 6th
- * line checks TCP options, if any. If any of these things are
- * different between the previous & current datagram, we send the
- * current datagram `uncompressed'.
- */
- if (((u_short *)ip)[0] != ((u_short *)&cs->cs_ip)[0]
- || ((u_short *)ip)[3] != ((u_short *)&cs->cs_ip)[3]
- || ((u_short *)ip)[4] != ((u_short *)&cs->cs_ip)[4]
- || TCPH_HDRLEN(th) != TCPH_HDRLEN(oth)
- || (deltaS > 5 && BCMP(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2))
- || (TCPH_HDRLEN(th) > 5 && BCMP(th + 1, oth + 1, (TCPH_HDRLEN(th) - 5) << 2))) {
- goto uncompressed;
- }
-
- /*
- * Figure out which of the changing fields changed. The
- * receiver expects changes in the order: urgent, window,
- * ack, seq (the order minimizes the number of temporaries
- * needed in this section of code).
- */
- if (TCPH_FLAGS(th) & TCP_URG) {
- deltaS = ntohs(th->urgp);
- ENCODEZ(deltaS);
- changes |= NEW_U;
- } else if (th->urgp != oth->urgp) {
- /* argh! URG not set but urp changed -- a sensible
- * implementation should never do this but RFC793
- * doesn't prohibit the change so we have to deal
- * with it. */
- goto uncompressed;
- }
-
- if ((deltaS = (u_short)(ntohs(th->wnd) - ntohs(oth->wnd))) != 0) {
- ENCODE(deltaS);
- changes |= NEW_W;
- }
-
- if ((deltaL = ntohl(th->ackno) - ntohl(oth->ackno)) != 0) {
- if (deltaL > 0xffff) {
- goto uncompressed;
- }
- deltaA = (u_short)deltaL;
- ENCODE(deltaA);
- changes |= NEW_A;
- }
-
- if ((deltaL = ntohl(th->seqno) - ntohl(oth->seqno)) != 0) {
- if (deltaL > 0xffff) {
- goto uncompressed;
- }
- deltaS = (u_short)deltaL;
- ENCODE(deltaS);
- changes |= NEW_S;
- }
-
- switch(changes) {
- case 0:
- /*
- * Nothing changed. If this packet contains data and the
- * last one didn't, this is probably a data packet following
- * an ack (normal on an interactive connection) and we send
- * it compressed. Otherwise it's probably a retransmit,
- * retransmitted ack or window probe. Send it uncompressed
- * in case the other side missed the compressed version.
- */
- if (IPH_LEN(ip) != IPH_LEN(&cs->cs_ip) &&
- ntohs(IPH_LEN(&cs->cs_ip)) == hlen) {
- break;
- }
-
- /* (fall through) */
-
- case SPECIAL_I:
- case SPECIAL_D:
- /*
- * actual changes match one of our special case encodings --
- * send packet uncompressed.
- */
- goto uncompressed;
-
- case NEW_S|NEW_A:
- if (deltaS == deltaA && deltaS == ntohs(IPH_LEN(&cs->cs_ip)) - hlen) {
- /* special case for echoed terminal traffic */
- changes = SPECIAL_I;
- cp = new_seq;
- }
- break;
-
- case NEW_S:
- if (deltaS == ntohs(IPH_LEN(&cs->cs_ip)) - hlen) {
- /* special case for data xfer */
- changes = SPECIAL_D;
- cp = new_seq;
- }
- break;
- }
-
- deltaS = (u_short)(ntohs(IPH_ID(ip)) - ntohs(IPH_ID(&cs->cs_ip)));
- if (deltaS != 1) {
- ENCODEZ(deltaS);
- changes |= NEW_I;
- }
- if (TCPH_FLAGS(th) & TCP_PSH) {
- changes |= TCP_PUSH_BIT;
- }
- /*
- * Grab the cksum before we overwrite it below. Then update our
- * state with this packet's header.
- */
- deltaA = ntohs(th->chksum);
- BCOPY(ip, &cs->cs_ip, hlen);
-
- /*
- * We want to use the original packet as our compressed packet.
- * (cp - new_seq) is the number of bytes we need for compressed
- * sequence numbers. In addition we need one byte for the change
- * mask, one for the connection id and two for the tcp checksum.
- * So, (cp - new_seq) + 4 bytes of header are needed. hlen is how
- * many bytes of the original packet to toss so subtract the two to
- * get the new packet size.
- */
- deltaS = (u_short)(cp - new_seq);
- if (!comp->compressSlot || comp->last_xmit != cs->cs_id) {
- comp->last_xmit = cs->cs_id;
- hlen -= deltaS + 4;
- if(pbuf_header(pb, -hlen)){
- /* Can we cope with this failing? Just assert for now */
- LWIP_ASSERT("pbuf_header failed\n", 0);
- }
- cp = (u_char *)pb->payload;
- *cp++ = (u_char)(changes | NEW_C);
- *cp++ = cs->cs_id;
- } else {
- hlen -= deltaS + 3;
- if(pbuf_header(pb, -hlen)) {
- /* Can we cope with this failing? Just assert for now */
- LWIP_ASSERT("pbuf_header failed\n", 0);
- }
- cp = (u_char *)pb->payload;
- *cp++ = (u_char)changes;
- }
- *cp++ = (u_char)(deltaA >> 8);
- *cp++ = (u_char)deltaA;
- BCOPY(new_seq, cp, deltaS);
- INCR(vjs_compressed);
- return (TYPE_COMPRESSED_TCP);
-
- /*
- * Update connection state cs & send uncompressed packet (that is,
- * a regular ip/tcp packet but with the 'conversation id' we hope
- * to use on future compressed packets in the protocol field).
- */
-uncompressed:
- BCOPY(ip, &cs->cs_ip, hlen);
- IPH_PROTO_SET(ip, cs->cs_id);
- comp->last_xmit = cs->cs_id;
- return (TYPE_UNCOMPRESSED_TCP);
-}
-
-/*
- * Called when we may have missed a packet.
- */
-void
-vj_uncompress_err(struct vjcompress *comp)
-{
- comp->flags |= VJF_TOSS;
- INCR(vjs_errorin);
-}
-
-/*
- * "Uncompress" a packet of type TYPE_UNCOMPRESSED_TCP.
- * Return 0 on success, -1 on failure.
- */
-int
-vj_uncompress_uncomp(struct pbuf *nb, struct vjcompress *comp)
-{
- register u_int hlen;
- register struct cstate *cs;
- register struct ip_hdr *ip;
-
- ip = (struct ip_hdr *)nb->payload;
- hlen = IPH_HL(ip) << 2;
- if (IPH_PROTO(ip) >= MAX_SLOTS
- || hlen + sizeof(struct tcp_hdr) > nb->len
- || (hlen += TCPH_HDRLEN(((struct tcp_hdr *)&((char *)ip)[hlen])) << 2)
- > nb->len
- || hlen > MAX_HDR) {
- PPPDEBUG(LOG_INFO, ("vj_uncompress_uncomp: bad cid=%d, hlen=%d buflen=%d\n",
- IPH_PROTO(ip), hlen, nb->len));
- comp->flags |= VJF_TOSS;
- INCR(vjs_errorin);
- return -1;
- }
- cs = &comp->rstate[comp->last_recv = IPH_PROTO(ip)];
- comp->flags &=~ VJF_TOSS;
- IPH_PROTO_SET(ip, IP_PROTO_TCP);
- BCOPY(ip, &cs->cs_ip, hlen);
- cs->cs_hlen = (u_short)hlen;
- INCR(vjs_uncompressedin);
- return 0;
-}
-
-/*
- * Uncompress a packet of type TYPE_COMPRESSED_TCP.
- * The packet is composed of a buffer chain and the first buffer
- * must contain an accurate chain length.
- * The first buffer must include the entire compressed TCP/IP header.
- * This procedure replaces the compressed header with the uncompressed
- * header and returns the length of the VJ header.
- */
-int
-vj_uncompress_tcp(struct pbuf **nb, struct vjcompress *comp)
-{
- u_char *cp;
- struct tcp_hdr *th;
- struct cstate *cs;
- u_short *bp;
- struct pbuf *n0 = *nb;
- u32_t tmp;
- u_int vjlen, hlen, changes;
-
- INCR(vjs_compressedin);
- cp = (u_char *)n0->payload;
- changes = *cp++;
- if (changes & NEW_C) {
- /*
- * Make sure the state index is in range, then grab the state.
- * If we have a good state index, clear the 'discard' flag.
- */
- if (*cp >= MAX_SLOTS) {
- PPPDEBUG(LOG_INFO, ("vj_uncompress_tcp: bad cid=%d\n", *cp));
- goto bad;
- }
-
- comp->flags &=~ VJF_TOSS;
- comp->last_recv = *cp++;
- } else {
- /*
- * this packet has an implicit state index. If we've
- * had a line error since the last time we got an
- * explicit state index, we have to toss the packet.
- */
- if (comp->flags & VJF_TOSS) {
- PPPDEBUG(LOG_INFO, ("vj_uncompress_tcp: tossing\n"));
- INCR(vjs_tossed);
- return (-1);
- }
- }
- cs = &comp->rstate[comp->last_recv];
- hlen = IPH_HL(&cs->cs_ip) << 2;
- th = (struct tcp_hdr *)&((u_char *)&cs->cs_ip)[hlen];
- th->chksum = htons((*cp << 8) | cp[1]);
- cp += 2;
- if (changes & TCP_PUSH_BIT) {
- TCPH_SET_FLAG(th, TCP_PSH);
- } else {
- TCPH_UNSET_FLAG(th, TCP_PSH);
- }
-
- switch (changes & SPECIALS_MASK) {
- case SPECIAL_I:
- {
- register u32_t i = ntohs(IPH_LEN(&cs->cs_ip)) - cs->cs_hlen;
- /* some compilers can't nest inline assembler.. */
- tmp = ntohl(th->ackno) + i;
- th->ackno = htonl(tmp);
- tmp = ntohl(th->seqno) + i;
- th->seqno = htonl(tmp);
- }
- break;
-
- case SPECIAL_D:
- /* some compilers can't nest inline assembler.. */
- tmp = ntohl(th->seqno) + ntohs(IPH_LEN(&cs->cs_ip)) - cs->cs_hlen;
- th->seqno = htonl(tmp);
- break;
-
- default:
- if (changes & NEW_U) {
- TCPH_SET_FLAG(th, TCP_URG);
- DECODEU(th->urgp);
- } else {
- TCPH_UNSET_FLAG(th, TCP_URG);
- }
- if (changes & NEW_W) {
- DECODES(th->wnd);
- }
- if (changes & NEW_A) {
- DECODEL(th->ackno);
- }
- if (changes & NEW_S) {
- DECODEL(th->seqno);
- }
- break;
- }
- if (changes & NEW_I) {
- DECODES(cs->cs_ip._id);
- } else {
- IPH_ID_SET(&cs->cs_ip, ntohs(IPH_ID(&cs->cs_ip)) + 1);
- IPH_ID_SET(&cs->cs_ip, htons(IPH_ID(&cs->cs_ip)));
- }
-
- /*
- * At this point, cp points to the first byte of data in the
- * packet. Fill in the IP total length and update the IP
- * header checksum.
- */
- vjlen = (u_short)(cp - (u_char*)n0->payload);
- if (n0->len < vjlen) {
- /*
- * We must have dropped some characters (crc should detect
- * this but the old slip framing won't)
- */
- PPPDEBUG(LOG_INFO, ("vj_uncompress_tcp: head buffer %d too short %d\n",
- n0->len, vjlen));
- goto bad;
- }
-
-#if BYTE_ORDER == LITTLE_ENDIAN
- tmp = n0->tot_len - vjlen + cs->cs_hlen;
- IPH_LEN_SET(&cs->cs_ip, htons((u_short)tmp));
-#else
- IPH_LEN_SET(&cs->cs_ip, htons(n0->tot_len - vjlen + cs->cs_hlen));
-#endif
-
- /* recompute the ip header checksum */
- bp = (u_short *) &cs->cs_ip;
- IPH_CHKSUM_SET(&cs->cs_ip, 0);
- for (tmp = 0; hlen > 0; hlen -= 2) {
- tmp += *bp++;
- }
- tmp = (tmp & 0xffff) + (tmp >> 16);
- tmp = (tmp & 0xffff) + (tmp >> 16);
- IPH_CHKSUM_SET(&cs->cs_ip, (u_short)(~tmp));
-
- /* Remove the compressed header and prepend the uncompressed header. */
- if(pbuf_header(n0, -((s16_t)(vjlen)))) {
- /* Can we cope with this failing? Just assert for now */
- LWIP_ASSERT("pbuf_header failed\n", 0);
- goto bad;
- }
-
- if(LWIP_MEM_ALIGN(n0->payload) != n0->payload) {
- struct pbuf *np, *q;
- u8_t *bufptr;
-
- np = pbuf_alloc(PBUF_RAW, n0->len + cs->cs_hlen, PBUF_POOL);
- if(!np) {
- PPPDEBUG(LOG_WARNING, ("vj_uncompress_tcp: realign failed\n"));
- goto bad;
- }
-
- if(pbuf_header(np, -cs->cs_hlen)) {
- /* Can we cope with this failing? Just assert for now */
- LWIP_ASSERT("pbuf_header failed\n", 0);
- goto bad;
- }
-
- bufptr = n0->payload;
- for(q = np; q != NULL; q = q->next) {
- MEMCPY(q->payload, bufptr, q->len);
- bufptr += q->len;
- }
-
- if(n0->next) {
- pbuf_chain(np, n0->next);
- pbuf_dechain(n0);
- }
- pbuf_free(n0);
- n0 = np;
- }
-
- if(pbuf_header(n0, cs->cs_hlen)) {
- struct pbuf *np;
-
- LWIP_ASSERT("vj_uncompress_tcp: cs->cs_hlen <= PBUF_POOL_BUFSIZE", cs->cs_hlen <= PBUF_POOL_BUFSIZE);
- np = pbuf_alloc(PBUF_RAW, cs->cs_hlen, PBUF_POOL);
- if(!np) {
- PPPDEBUG(LOG_WARNING, ("vj_uncompress_tcp: prepend failed\n"));
- goto bad;
- }
- pbuf_cat(np, n0);
- n0 = np;
- }
- LWIP_ASSERT("n0->len >= cs->cs_hlen", n0->len >= cs->cs_hlen);
- MEMCPY(n0->payload, &cs->cs_ip, cs->cs_hlen);
-
- *nb = n0;
-
- return vjlen;
-
-bad:
- comp->flags |= VJF_TOSS;
- INCR(vjs_errorin);
- return (-1);
-}
-
-#endif /* VJ_SUPPORT */
-
-#endif /* PPP_SUPPORT */
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