Diff: lwip/netif/ppp/vj.c

Revision:

12:8dc6b255af6c

Parent:

11:da4498f591ee

--- a/lwip/netif/ppp/vj.c	Thu Aug 05 15:01:33 2010 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,652 +0,0 @@
-/*
- * 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.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_OFFSET(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_OFFSET(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_OFFSET(th) != TCPH_OFFSET(oth) 
-      || (deltaS > 5 && BCMP(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) 
-      || (TCPH_OFFSET(th) > 5 && BCMP(th + 1, oth + 1, (TCPH_OFFSET(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_OFFSET(((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 = (u8_t *)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 */