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-rw-r--r--lwip/src/netif/ppp/vj.c685
1 files changed, 685 insertions, 0 deletions
diff --git a/lwip/src/netif/ppp/vj.c b/lwip/src/netif/ppp/vj.c
new file mode 100644
index 0000000..3fecba6
--- /dev/null
+++ b/lwip/src/netif/ppp/vj.c
@@ -0,0 +1,685 @@
+/*
+ * 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 "netif/ppp/ppp_opts.h"
+#if PPP_SUPPORT && VJ_SUPPORT /* don't build if not configured for use in lwipopts.h */
+
+#include "netif/ppp/ppp_impl.h"
+#include "netif/ppp/pppdebug.h"
+
+#include "netif/ppp/vj.h"
+
+#include <string.h>
+
+#if LINK_STATS
+#define INCR(counter) ++comp->stats.counter
+#else
+#define INCR(counter)
+#endif
+
+void
+vj_compress_init(struct vjcompress *comp)
+{
+ u8_t i;
+ 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 ((u16_t)(n) >= 256) { \
+ *cp++ = 0; \
+ cp[1] = (u8_t)(n); \
+ cp[0] = (u8_t)((n) >> 8); \
+ cp += 2; \
+ } else { \
+ *cp++ = (u8_t)(n); \
+ } \
+}
+#define ENCODEZ(n) { \
+ if ((u16_t)(n) >= 256 || (u16_t)(n) == 0) { \
+ *cp++ = 0; \
+ cp[1] = (u8_t)(n); \
+ cp[0] = (u8_t)((n) >> 8); \
+ cp += 2; \
+ } else { \
+ *cp++ = (u8_t)(n); \
+ } \
+}
+
+#define DECODEL(f) { \
+ if (*cp == 0) {\
+ u32_t tmp_ = lwip_ntohl(f) + ((cp[1] << 8) | cp[2]); \
+ (f) = lwip_htonl(tmp_); \
+ cp += 3; \
+ } else { \
+ u32_t tmp_ = lwip_ntohl(f) + (u32_t)*cp++; \
+ (f) = lwip_htonl(tmp_); \
+ } \
+}
+
+#define DECODES(f) { \
+ if (*cp == 0) {\
+ u16_t tmp_ = lwip_ntohs(f) + (((u16_t)cp[1] << 8) | cp[2]); \
+ (f) = lwip_htons(tmp_); \
+ cp += 3; \
+ } else { \
+ u16_t tmp_ = lwip_ntohs(f) + (u16_t)*cp++; \
+ (f) = lwip_htons(tmp_); \
+ } \
+}
+
+#define DECODEU(f) { \
+ if (*cp == 0) {\
+ (f) = lwip_htons(((u16_t)cp[1] << 8) | cp[2]); \
+ cp += 3; \
+ } else { \
+ (f) = lwip_htons((u16_t)*cp++); \
+ } \
+}
+
+/* Helper structures for unaligned *u32_t and *u16_t accesses */
+#ifdef PACK_STRUCT_USE_INCLUDES
+# include "arch/bpstruct.h"
+#endif
+PACK_STRUCT_BEGIN
+struct vj_u32_t {
+ PACK_STRUCT_FIELD(u32_t v);
+} PACK_STRUCT_STRUCT;
+PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+# include "arch/epstruct.h"
+#endif
+
+#ifdef PACK_STRUCT_USE_INCLUDES
+# include "arch/bpstruct.h"
+#endif
+PACK_STRUCT_BEGIN
+struct vj_u16_t {
+ PACK_STRUCT_FIELD(u16_t v);
+} PACK_STRUCT_STRUCT;
+PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+# include "arch/epstruct.h"
+#endif
+
+/*
+ * 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.
+ */
+u8_t
+vj_compress_tcp(struct vjcompress *comp, struct pbuf **pb)
+{
+ struct pbuf *np = *pb;
+ struct ip_hdr *ip = (struct ip_hdr *)np->payload;
+ struct cstate *cs = comp->last_cs->cs_next;
+ u16_t ilen = IPH_HL(ip);
+ u16_t hlen;
+ struct tcp_hdr *oth;
+ struct tcp_hdr *th;
+ u16_t deltaS, deltaA = 0;
+ u32_t deltaL;
+ u32_t changes = 0;
+ u8_t new_seq[16];
+ u8_t *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)) || np->tot_len < 40) {
+ return (TYPE_IP);
+ }
+ th = (struct tcp_hdr *)&((struct vj_u32_t*)ip)[ilen];
+ if ((TCPH_FLAGS(th) & (TCP_SYN|TCP_FIN|TCP_RST|TCP_ACK)) != TCP_ACK) {
+ return (TYPE_IP);
+ }
+
+ /* Check that the TCP/IP headers are contained in the first buffer. */
+ hlen = ilen + TCPH_HDRLEN(th);
+ hlen <<= 2;
+ if (np->len < hlen) {
+ PPPDEBUG(LOG_INFO, ("vj_compress_tcp: header len %d spans buffers\n", hlen));
+ return (TYPE_IP);
+ }
+
+ /* TCP stack requires that we don't change the packet payload, therefore we copy
+ * the whole packet before compression. */
+ np = pbuf_clone(PBUF_RAW, PBUF_RAM, *pb);
+ if (!np) {
+ return (TYPE_IP);
+ }
+
+ *pb = np;
+ ip = (struct ip_hdr *)np->payload;
+
+ /*
+ * 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 (!ip4_addr_cmp(&ip->src, &cs->cs_ip.src)
+ || !ip4_addr_cmp(&ip->dest, &cs->cs_ip.dest)
+ || (*(struct vj_u32_t*)th).v != (((struct vj_u32_t*)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]).v) {
+ /*
+ * 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.
+ */
+ struct cstate *lcs;
+ struct cstate *lastcs = comp->last_cs;
+
+ do {
+ lcs = cs; cs = cs->cs_next;
+ INCR(vjs_searches);
+ if (ip4_addr_cmp(&ip->src, &cs->cs_ip.src)
+ && ip4_addr_cmp(&ip->dest, &cs->cs_ip.dest)
+ && (*(struct vj_u32_t*)th).v == (((struct vj_u32_t*)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]).v) {
+ 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;
+ 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 *)&((struct vj_u32_t*)&cs->cs_ip)[ilen];
+ deltaS = ilen;
+
+ /*
+ * 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 ((((struct vj_u16_t*)ip)[0]).v != (((struct vj_u16_t*)&cs->cs_ip)[0]).v
+ || (((struct vj_u16_t*)ip)[3]).v != (((struct vj_u16_t*)&cs->cs_ip)[3]).v
+ || (((struct vj_u16_t*)ip)[4]).v != (((struct vj_u16_t*)&cs->cs_ip)[4]).v
+ || 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 = lwip_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 = (u16_t)(lwip_ntohs(th->wnd) - lwip_ntohs(oth->wnd))) != 0) {
+ ENCODE(deltaS);
+ changes |= NEW_W;
+ }
+
+ if ((deltaL = lwip_ntohl(th->ackno) - lwip_ntohl(oth->ackno)) != 0) {
+ if (deltaL > 0xffff) {
+ goto uncompressed;
+ }
+ deltaA = (u16_t)deltaL;
+ ENCODE(deltaA);
+ changes |= NEW_A;
+ }
+
+ if ((deltaL = lwip_ntohl(th->seqno) - lwip_ntohl(oth->seqno)) != 0) {
+ if (deltaL > 0xffff) {
+ goto uncompressed;
+ }
+ deltaS = (u16_t)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) &&
+ lwip_ntohs(IPH_LEN(&cs->cs_ip)) == hlen) {
+ break;
+ }
+ /* no 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 == lwip_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 == lwip_ntohs(IPH_LEN(&cs->cs_ip)) - hlen) {
+ /* special case for data xfer */
+ changes = SPECIAL_D;
+ cp = new_seq;
+ }
+ break;
+ default:
+ break;
+ }
+
+ deltaS = (u16_t)(lwip_ntohs(IPH_ID(ip)) - lwip_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 = lwip_ntohs(th->chksum);
+ MEMCPY(&cs->cs_ip, 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 = (u16_t)(cp - new_seq);
+ if (!comp->compressSlot || comp->last_xmit != cs->cs_id) {
+ comp->last_xmit = cs->cs_id;
+ hlen -= deltaS + 4;
+ if (pbuf_remove_header(np, hlen)){
+ /* Can we cope with this failing? Just assert for now */
+ LWIP_ASSERT("pbuf_remove_header failed\n", 0);
+ }
+ cp = (u8_t*)np->payload;
+ *cp++ = (u8_t)(changes | NEW_C);
+ *cp++ = cs->cs_id;
+ } else {
+ hlen -= deltaS + 3;
+ if (pbuf_remove_header(np, hlen)) {
+ /* Can we cope with this failing? Just assert for now */
+ LWIP_ASSERT("pbuf_remove_header failed\n", 0);
+ }
+ cp = (u8_t*)np->payload;
+ *cp++ = (u8_t)changes;
+ }
+ *cp++ = (u8_t)(deltaA >> 8);
+ *cp++ = (u8_t)deltaA;
+ MEMCPY(cp, new_seq, 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:
+ MEMCPY(&cs->cs_ip, 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)
+{
+ u32_t hlen;
+ struct cstate *cs;
+ 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_BYTES((struct tcp_hdr *)&((char *)ip)[hlen]))
+ > 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));
+ vj_uncompress_err(comp);
+ return -1;
+ }
+ cs = &comp->rstate[comp->last_recv = IPH_PROTO(ip)];
+ comp->flags &=~ VJF_TOSS;
+ IPH_PROTO_SET(ip, IP_PROTO_TCP);
+ /* copy from/to bigger buffers checked above instead of cs->cs_ip and ip
+ just to help static code analysis to see this is correct ;-) */
+ MEMCPY(&cs->cs_hdr, nb->payload, hlen);
+ cs->cs_hlen = (u16_t)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)
+{
+ u8_t *cp;
+ struct tcp_hdr *th;
+ struct cstate *cs;
+ struct vj_u16_t *bp;
+ struct pbuf *n0 = *nb;
+ u32_t tmp;
+ u32_t vjlen, hlen, changes;
+
+ INCR(vjs_compressedin);
+ cp = (u8_t*)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 *)&((u8_t*)&cs->cs_ip)[hlen];
+ th->chksum = lwip_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:
+ {
+ u32_t i = lwip_ntohs(IPH_LEN(&cs->cs_ip)) - cs->cs_hlen;
+ /* some compilers can't nest inline assembler.. */
+ tmp = lwip_ntohl(th->ackno) + i;
+ th->ackno = lwip_htonl(tmp);
+ tmp = lwip_ntohl(th->seqno) + i;
+ th->seqno = lwip_htonl(tmp);
+ }
+ break;
+
+ case SPECIAL_D:
+ /* some compilers can't nest inline assembler.. */
+ tmp = lwip_ntohl(th->seqno) + lwip_ntohs(IPH_LEN(&cs->cs_ip)) - cs->cs_hlen;
+ th->seqno = lwip_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, lwip_ntohs(IPH_ID(&cs->cs_ip)) + 1);
+ IPH_ID_SET(&cs->cs_ip, lwip_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 = (u16_t)(cp - (u8_t*)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, lwip_htons((u16_t)tmp));
+#else
+ IPH_LEN_SET(&cs->cs_ip, lwip_htons(n0->tot_len - vjlen + cs->cs_hlen));
+#endif
+
+ /* recompute the ip header checksum */
+ bp = (struct vj_u16_t*) &cs->cs_ip;
+ IPH_CHKSUM_SET(&cs->cs_ip, 0);
+ for (tmp = 0; hlen > 0; hlen -= 2) {
+ tmp += (*bp++).v;
+ }
+ tmp = (tmp & 0xffff) + (tmp >> 16);
+ tmp = (tmp & 0xffff) + (tmp >> 16);
+ IPH_CHKSUM_SET(&cs->cs_ip, (u16_t)(~tmp));
+
+ /* Remove the compressed header and prepend the uncompressed header. */
+ if (pbuf_remove_header(n0, vjlen)) {
+ /* Can we cope with this failing? Just assert for now */
+ LWIP_ASSERT("pbuf_remove_header failed\n", 0);
+ goto bad;
+ }
+
+ if(LWIP_MEM_ALIGN(n0->payload) != n0->payload) {
+ struct pbuf *np;
+
+#if IP_FORWARD
+ /* If IP forwarding is enabled we are using a PBUF_LINK packet type so
+ * the packet is being allocated with enough header space to be
+ * forwarded (to Ethernet for example).
+ */
+ np = pbuf_alloc(PBUF_LINK, n0->len + cs->cs_hlen, PBUF_POOL);
+#else /* IP_FORWARD */
+ np = pbuf_alloc(PBUF_RAW, n0->len + cs->cs_hlen, PBUF_POOL);
+#endif /* IP_FORWARD */
+ if(!np) {
+ PPPDEBUG(LOG_WARNING, ("vj_uncompress_tcp: realign failed\n"));
+ goto bad;
+ }
+
+ if (pbuf_remove_header(np, cs->cs_hlen)) {
+ /* Can we cope with this failing? Just assert for now */
+ LWIP_ASSERT("pbuf_remove_header failed\n", 0);
+ goto bad;
+ }
+
+ pbuf_take(np, n0->payload, n0->len);
+
+ if(n0->next) {
+ pbuf_chain(np, n0->next);
+ pbuf_dechain(n0);
+ }
+ pbuf_free(n0);
+ n0 = np;
+ }
+
+ if (pbuf_add_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:
+ vj_uncompress_err(comp);
+ return (-1);
+}
+
+#endif /* PPP_SUPPORT && VJ_SUPPORT */