static struct mbuf *
sync_LayerPush(struct bundle *bundle, struct link *l, struct mbuf *bp,
int pri, u_short *proto)
{
log_DumpBp(LogSYNC, "Write", bp);
m_settype(bp, MB_SYNCOUT);
return bp;
}
static struct mbuf *
sync_LayerPull(struct bundle *b, struct link *l, struct mbuf *bp,
u_short *proto)
{
struct physical *p = link2physical(l);
if (!p)
log_Printf(LogERROR, "Can't Pull a sync packet from a logical link\n");
else {
log_DumpBp(LogSYNC, "Read", bp);
/* Either done here or by the HDLC layer */
p->hdlc.lqm.SaveInOctets += m_length(bp) + 1;
p->hdlc.lqm.SaveInPackets++;
m_settype(bp, MB_SYNCIN);
}
return bp;
}
static void
ChapOutput(struct physical *physical, u_int code, u_int id,
const u_char *ptr, int count, const char *text)
{
int plen;
struct fsmheader lh;
struct mbuf *bp;
plen = sizeof(struct fsmheader) + count;
lh.code = code;
lh.id = id;
lh.length = htons(plen);
bp = m_get(plen, MB_CHAPOUT);
memcpy(MBUF_CTOP(bp), &lh, sizeof(struct fsmheader));
if (count)
memcpy(MBUF_CTOP(bp) + sizeof(struct fsmheader), ptr, count);
log_DumpBp(LogDEBUG, "ChapOutput", bp);
if (text == NULL)
log_Printf(LogPHASE, "Chap Output: %s\n", chapcodes[code]);
else
log_Printf(LogPHASE, "Chap Output: %s (%s)\n", chapcodes[code], text);
link_PushPacket(&physical->link, bp, physical->dl->bundle,
LINK_QUEUES(&physical->link) - 1, PROTO_CHAP);
}
u_char
sl_compress_tcp(struct mbuf * m,
struct ip * ip,
struct slcompress *comp,
struct slstat *slstat,
int compress_cid)
{
register struct cstate *cs = comp->last_cs->cs_next;
register u_int hlen = ip->ip_hl;
register struct tcphdr *oth;
register struct tcphdr *th;
register u_int deltaS, deltaA;
register u_int changes = 0;
u_char new_seq[16];
register u_char *cp = new_seq;
/*
* 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). (We assume that
* the caller has already made sure the packet is IP proto TCP).
*/
if ((ip->ip_off & htons(0x3fff)) || m->m_len < 40) {
log_Printf(LogDEBUG, "??? 1 ip_off = %x, m_len = %lu\n",
ntohs(ip->ip_off), (unsigned long)m->m_len);
log_DumpBp(LogDEBUG, "", m);
return (TYPE_IP);
}
th = (struct tcphdr *) & ((int *) ip)[hlen];
if ((th->th_flags & (TH_SYN | TH_FIN | TH_RST | TH_ACK)) != TH_ACK) {
log_Printf(LogDEBUG, "??? 2 th_flags = %x\n", th->th_flags);
log_DumpBp(LogDEBUG, "", m);
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.
*/
slstat->sls_packets++;
if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr ||
ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr ||
*(int *) th != ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl]) {
/*
* 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;
slstat->sls_searches++;
if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr
&& ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr
&& *(int *) th == ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl])
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.
*/
slstat->sls_misses++;
comp->last_cs = lcs;
#define THOFFSET(th) (th->th_off)
hlen += th->th_off;
hlen <<= 2;
if (hlen > m->m_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;
}
}
/*
* 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'.
*/
oth = (struct tcphdr *) & ((int *) &cs->cs_ip)[hlen];
deltaS = hlen;
hlen += th->th_off;
hlen <<= 2;
if (hlen > m->m_len)
return (TYPE_IP);
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] ||
THOFFSET(th) != THOFFSET(oth) ||
(deltaS > 5 &&
memcmp(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) ||
(THOFFSET(th) > 5 &&
memcmp(th + 1, oth + 1, (THOFFSET(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 (th->th_flags & TH_URG) {
deltaS = ntohs(th->th_urp);
ENCODEZ(deltaS);
changes |= NEW_U;
} else if (th->th_urp != oth->th_urp) {
/*
* 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;
}
deltaS = (u_short) (ntohs(th->th_win) - ntohs(oth->th_win));
if (deltaS) {
ENCODE(deltaS);
changes |= NEW_W;
}
deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack);
if (deltaA) {
if (deltaA > 0xffff) {
goto uncompressed;
}
ENCODE(deltaA);
changes |= NEW_A;
}
deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq);
if (deltaS) {
if (deltaS > 0xffff) {
goto uncompressed;
}
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 (ip->ip_len != cs->cs_ip.ip_len &&
ntohs(cs->cs_ip.ip_len) == hlen)
break;
/* FALLTHROUGH */
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(cs->cs_ip.ip_len) - hlen) {
/* special case for echoed terminal traffic */
changes = SPECIAL_I;
cp = new_seq;
}
break;
case NEW_S:
if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
/* special case for data xfer */
changes = SPECIAL_D;
cp = new_seq;
}
break;
}
deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id);
if (deltaS != 1) {
ENCODEZ(deltaS);
changes |= NEW_I;
}
if (th->th_flags & TH_PUSH)
changes |= TCP_PUSH_BIT;
/*
* Grab the cksum before we overwrite it below. Then update our state with
* this packet's header.
*/
deltaA = ntohs(th->th_sum);
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 = cp - new_seq;
cp = (u_char *) ip;
/*
* Since fastq traffic can jump ahead of the background traffic, we don't
* know what order packets will go on the line. In this case, we always
* send a "new" connection id so the receiver state stays synchronized.
*/
if (comp->last_xmit == cs->cs_id && compress_cid) {
hlen -= deltaS + 3;
cp += hlen;
*cp++ = changes;
} else {
comp->last_xmit = cs->cs_id;
hlen -= deltaS + 4;
cp += hlen;
*cp++ = changes | NEW_C;
*cp++ = cs->cs_id;
}
m->m_len -= hlen;
m->m_offset += hlen;
*cp++ = deltaA >> 8;
*cp++ = deltaA;
memcpy(cp, new_seq, deltaS);
slstat->sls_compressed++;
return (TYPE_COMPRESSED_TCP);
/*
* Update connection state cs & send uncompressed packet ('uncompressed'
* means 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);
ip->ip_p = cs->cs_id;
comp->last_xmit = cs->cs_id;
return (TYPE_UNCOMPRESSED_TCP);
}
