From owner-cvs-all  Wed Nov 24 18:47:10 1999
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From: Brian Somers <brian@FreeBSD.org>
Date: Wed, 24 Nov 1999 18:47:06 -0800 (PST)
To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: cvs commit: src/usr.sbin/ppp bundle.c bundle.h command.c
         datalink.c datalink.h ether.c i4b.c mp.c physical.c physical.h
         tty.c udp.c
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brian       1999/11/24 18:47:06 PST

  Modified files:
    usr.sbin/ppp         bundle.c bundle.h command.c datalink.c 
                         datalink.h ether.c i4b.c mp.c physical.c 
                         physical.h tty.c udp.c 
  Log:
  Rewrite the link descriptor transfer code in MP mode.
  
  Previously, ppp attempted to bind() to a local domain tcp socket
  based on the peer authname & enddisc.  If it succeeded, it listen()ed
  and became MP server.  If it failed, it connect()ed and became MP
  client.  The server then select()ed on the descriptor, accept()ed
  it and wrote its pid to it then read the link data & link file descriptor,
  and finally sent an ack (``!'').  The client would read() the server
  pid, transfer the link lock to that pid, send the link data & descriptor
  and read the ack.  It would then close the descriptor and clean up.
  
  There was a race between the bind() and listen() where someone could
  attempt to connect() and fail.
  
  This change removes the race.  Now ppp makes the RCVBUF big enough on a
  socket descriptor and attempts to bind() to a local domain *udp* socket
  (same name as before).  If it succeeds, it becomes MP server.  If it
  fails, it sets the SNDBUF and connect()s, becoming MP client.  The server
  select()s on the descriptor and recvmsg()s the message, insisting on at
  least two descriptors (plus the link data).  It uses the second descriptor
  to write() its pid then read()s an ack (``!'').  The client creates a
  socketpair() and sendmsg()s the link data, link descriptor and one of
  the socketpair descriptors.  It then read()s the server pid from the
  other socketpair descriptor, transfers any locks and write()s an ack.
  
  Now, there can be no race, and a connect() failure indicates a stale
  socket file.
  
  This also fixes MP ppp over ethernet, where the struct msghdr was being
  misconstructed when transferring the control socket descriptor.
  
  Also, if we fail to send the link, don't hang around in a ``session
  owner'' state, just do the setsid() and fork() if it's required to
  disown a tty.
  
  UDP idea suggested by: Chris Bennet from Mindspring at FreeBSDCon
  
  Revision  Changes    Path
  1.76      +136 -82   src/usr.sbin/ppp/bundle.c
  1.30      +3 -2      src/usr.sbin/ppp/bundle.h
  1.223     +2 -2      src/usr.sbin/ppp/command.c
  1.52      +5 -6      src/usr.sbin/ppp/datalink.c
  1.12      +2 -2      src/usr.sbin/ppp/datalink.h
  1.8       +2 -2      src/usr.sbin/ppp/ether.c
  1.6       +2 -2      src/usr.sbin/ppp/i4b.c
  1.33      +36 -25    src/usr.sbin/ppp/mp.c
  1.31      +20 -14    src/usr.sbin/ppp/physical.c
  1.19      +5 -5      src/usr.sbin/ppp/physical.h
  1.19      +2 -2      src/usr.sbin/ppp/tty.c
  1.9       +2 -2      src/usr.sbin/ppp/udp.c



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