freebsd-dev/usr.sbin/ppp/modem.h
brian 7d986324c0 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.

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!
1998-01-10 01:55:11 +00:00

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1.6 KiB
C

/*
* Written by Toshiharu OHNO (tony-o@iij.ad.jp)
*
* Copyright (C) 1993, Internet Initiative Japan, Inc. All rights reserverd.
*
* 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 Internet Initiative Japan. The name of the
* IIJ 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.
*
* $Id: modem.h,v 1.14 1997/11/22 03:37:41 brian Exp $
*
* TODO:
*/
extern int RawModem(void);
extern void UpModem(int);
extern void DownModem(int);
extern void WriteModem(int, const char *, int);
extern void ModemStartOutput(int);
extern int OpenModem(void);
extern int ModemSpeed(void);
extern int ModemQlen(void);
extern int DialModem(void);
extern speed_t IntToSpeed(int);
extern void ModemTimeout(void *v);
extern void DownConnection(void);
extern void ModemOutput(int, struct mbuf *);
extern int ChangeParity(const char *);
extern void HangupModem(int);
extern int ShowModemStatus(struct cmdargs const *);
extern void Enqueue(struct mqueue *, struct mbuf *);
extern struct mbuf *Dequeue(struct mqueue *);
extern void SequenceQueues(void);
extern void ModemAddInOctets(int);
extern void ModemAddOutOctets(int);