From 56909f6cc6f48c5a163fcd09e26c6700017e12f4 Mon Sep 17 00:00:00 2001
From: brian <brian@cvs.openbsd.org>
Date: Sat, 10 Jan 1998 01:55:18 +0000
Subject: Implement Reset{Req,Ack} properly, as per rfc 1962. (I completely
 mis-read the rfc last time 'round!)

This means:
  o Better CCP/WARN Reset diagnostics.
  o After we've sent a REQ and before we've received an ACK, we drop
    incoming compressed data and send another REQ.
  o Before sending an ACK, re-sequence all pending PRI_NORMAL data in
    the modem queue so that pending packets won't get to the peer
    *after* the ResetAck.
  o Send ACKs with the `identifier' from the REQ frame.
  o After we've received a correct ACK, duplicate ACKs are ok (and will
    reset our history).
  o Incorrect ACKs (not matching the last REQ) are moaned about and dropped.

Also,

  o Calculate the correct FCS after compressing a packet.  DEFLATE
    *may* produce an mbuf with more than a single link in the chain,
    but HdlcOutput didn't know how to calculate the FCS :-(
  o Make `struct fsm'::reqid a u_char, not an int.
    This fix will prevent us from sending id `255' 2,000,000,000 times
    before wrapping to `0' for another 2,000,000,000 sends :-/
  o Bump the version number a little (it should already have been at 1.6).

The end result:  DEFLATE now works over an unreliable link layer.
                 I can txfr a 1.5Mb kernel over a (rather bad) null-modem
                 cable at an average of 21679 bytes per second using rcp.
Repeat after me: Don't test compression using a loopback ppp/tcp setup as
                 we never lose packets and therefore never have to reset!
---
 usr.sbin/ppp/modem.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

(limited to 'usr.sbin/ppp/modem.c')

diff --git a/usr.sbin/ppp/modem.c b/usr.sbin/ppp/modem.c
index e4b8d98e95c..b1bb7808b4a 100644
--- a/usr.sbin/ppp/modem.c
+++ b/usr.sbin/ppp/modem.c
@@ -17,7 +17,7 @@
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
- * $Id: modem.c,v 1.7 1997/12/30 23:22:37 brian Exp $
+ * $Id: modem.c,v 1.8 1998/01/10 01:55:16 brian Exp $
  *
  *  TODO:
  */
@@ -94,7 +94,7 @@ Enqueue(struct mqueue * queue, struct mbuf * bp)
 }
 
 struct mbuf *
-Dequeue(struct mqueue * queue)
+Dequeue(struct mqueue *queue)
 {
   struct mbuf *bp;
 
@@ -112,6 +112,14 @@ Dequeue(struct mqueue * queue)
   return (bp);
 }
 
+void
+SequenceQueues()
+{
+  LogPrintf(LogDEBUG, "SequenceQueues\n");
+  while (OutputQueues[PRI_NORMAL].qlen)
+    Enqueue(OutputQueues + PRI_LINK, Dequeue(OutputQueues + PRI_NORMAL));
+}
+
 static struct speeds {
   int nspeed;
   speed_t speed;
-- 
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