router/functions:
	To test  $(lreplace ...)  function
	To document  lreplace, and lappend

Known/suspected bugs/Missing Features on current Zmailer sources

- Somewhere ? (smtpserver, and perhaps smtp transport agent ?)
	Implement OUTBOUND message size limit mechanism.
	Possibly a multi-value system which works against
	IP/reversed domain information, and adjust maximum
	inbound message size at the smtpserver per that
	given server.

	A further complication is need to limit outbound
	email's sizes when the inbound size is limited so
	that our system will not send out anything to which
	error report size is larger than out inbound limit.

	Problem being, of course, that outbound channels
	need to interrogate that same configuration mechanism
	to do "Sorry, this is too large for sending" processing.


- scheduler:
	Sometimes will generate spurious successfull-delivery-
	reports when the command is retried, and the tag selector
	is unable to start the real processor.

	resync mechanism needs to be rewritten; now it throws away
	all info about the file, while it should only scan thru all
	data, and sync in-core status with the file.
		(incomplete code skeleton written for this)
		( sync_cfps() is that skeleton.. )

	- Delivery messages plain-text part needs easier human
	  understandable format on the messages.

	- Does the NOTIFY=SUCCESS work ok ?
		[2.99.49b2 - now it should ("ok3" status code)]

	Have two waiting threads (one message each):
	- start both of them with ETRN
	- both issue report of "retryat +nn"
	- both are rescheduled about immediately..
	- system spins (FAST) on those two...
		(Fixed ?  Haven't seen this for a while)

	- New cfg param:  maxha -- max age that a child-process can be
	  active, and the scheduler will wait for that much after the
	  feed for any "#hungry" message from (to detect hung-up processes)
	- Another:  maxlife  -- maximum lifetime for a transport agent
	  for limiting the time a smtp-channel stays open for a long-
	  living connection...

- smtpserver
  - VERIFY: behaviour on BDAT (and DATA) phases when the disk fills
  -	Report that if the router subprocess crashes, interactive
	processing goes into mixed state -- it reports 2XX, and
	yet claims to be in wrong state (MAIL FROM or RCPT TO ?
	I have forgotten..)

  - accept email to postmaster(s), never mind what else policy testers
    have determined...
  - "-s" option processing is entirely wrong...
  - The connection source IP reversal is not verified paranoidly, we
    may accept people who claim dishonest reversals..  (But then we
    can test against their IP address..)
  - Have some flag passing mechanism from the initial policy db
    back to the smtpserver proper so that it can:
	- give more meaningfull explanations of rejection reason
	- run more verification subroutines on addresses per policy
	  driver control; namely  "this domain can be valid source only
				   when it is coming from this IP address"
	  type of checkup...
  - more complete address processing into policytest() routines
  - Complete the fqdn address top-level domain existence verification
    test activation based on:
	- If policytest is in use, do it
	- If "-sR" mode is on, do it

- "make install" does not handle manual-page installation properly,
  also alternate-root installation has a few odd ends (vacation
  man-page, libc/libzmailer.a, (libc)include/zmailer.h )

- Integrate transports/fuzzyalias/ into the configuration system

- Manuals leave a lot to desire.. Especially a good users/administrators
  manual is in need
	[July 1997: technical writers are hard at work on this one]
	[April 1998: Completing the work is at Matti's hands..]


- All transport agents:
	- Unify the content MIME processing routines;  Construct them
	  to be a common sub-layer ?
	- Do not decode Q-P or Base-64 if the resulting material exceeds
	  RFC-821/RFC-822 line length limits (or whatever limits have
	  been set).

- transports/sm/sm.c:
	- what UID it runs programs like procmail with ?
	  What uid it should run them ?
	  I don't think the current (up to 2.99.49p*) way of running
	  procmail/cyrus is entirely safe.
	- I have gotten comments that they are suid/sgid root/root
	  at most installations, and indeed so procmail is at my
	  workstation too...
	- DSN handling flags ?
	- "localize" the destination address properly.  That is, strip
	  quotes from around a quoted destination address according to
	  the RFC822 syntax. -- Is this always correct ?

- router:
	- Log-file option does not set (reliably) the logfile
	  to be something else, than the default.
	** Well...  See  $MAILSHARE/cf/standard.cf:  dribble routine, and
	** especially its calls!  Not so easy to configure externally...
	- SIGHUP log close/reopen does not work quite as one would
	  want it to work.  In fact it does not close the files, rather
	  opens new ones after it has dup()ed old descriptors away from
	  the harms way..  e.g. it leaks log-files..

- post-install-check
	- check existence of mailq/tcp in /etc/services
	- check MAILVAR/MAILSHARE/POSTOFFICE protections
	- check "nobody" and "daemon" accounts

- systemwide .forward checker
	- iterate all users in the system
	- check peoples directory ownerships and permissions
	- check peoples .forward ownerships and permissions

- Need a program to verify that given configuration is ok, checks
  for things like:
	- "nobody" userid
	- scheduler's resource control working to the maximum
	  extend that system supports
	- mmap() correct operation  (GNU autoconf does this)
	- sprintf() return type is autoconfigured correctly

- Need a program to run thru various file permission checks:
	- $MAILVAR/db/ -dir, and files in it
	- $MAILVAR/lists/ -dir, and files in it
	- ~/.forward -files (and home directories)

- transports/smtp/smtp.c: (and scheduler)
	- VERIFY: BDAT (and DATA) status processing in case the remote
	  yields disk-full temporary error.
	- To rewrite the MX processing in streamlined flashion (see next)
	- In case two domains have common (sub-)set of MX servers, and
	  we have been feeding mail to domain A thru MX-server B, and
	  now we change to deliver domain C which too has MX-server B.
	  We are to reuse the already open channel to server B to feed
	  the message out even though the domain C might have had server
	  D with lower preferrence..
	  (Noting that all MX-hosts with same or larger privilege,
	   than ourselves are to be pre-removed from the list!)

- IPv6 stuff:
	- lib/selfaddrs.c: Don't properly do automatic IPv6 interface address
			   picking (IPv4 is ok)
	- libc/myhostname.c: don't do automatic IPv6
	- scheduler/mailq.c: don't do IPv6 connect
	- transports/hold/hold.c: incomplete NS/AAAA, no IPv6 PTR
	- transports/mailbox/mailbox.c: BIFF gethostbyname() ?

- whole chain (smtpserver/router/mailbox+hold):
	- Have a NEW pseudoheader (NRCPT) in addition to the ORCPT, which
	  we now (in not completely kosher manner) create, if we don't get
	  it originally.  That is, similar entry for traversing unchanged
	  thru the router to tell what address we got as input.
	  (Thru some pseudo-alias..)
	- Retain (in some TA-header object) the original "MAIL FROM:<..>"
	  address, and be able to store it into the MAILBOX channel.
	  (That is, don't let the routing process to alter this!)

- transports/mailbox/mailbox.c:
	- Store the ORCPT information into a "X-Orcpt-To: "-header
	- Store the NRCPT information into a "X-InRcpt-To: "-header
	- Store the ENVID information into a "X-Envid: "-header
	- Store the original FROM:<..> into a "X-OrigFrom: "-header

	- Provide aforementioned "headers" also as environment variables
	  to the pipes
	- At the router:run_rfc822(): if the message has these headers,
	  purge them away.

- Autoconfig problems:
	- System mailbox locking schemes are sometimes non-obvious..
	- For the last PERHAPS must back introduce the host-configuring
	  for describing host-system dependencies like mailbox-lock schemes

- Got mail with a suggestion: (via zmailer-list)

 I suggest you to improve the 'crossbar' function of 'router'.
 It might return a list of header rewrite functions as well
 as a single function like now. So different rewrite methods
 could be applied for sender and recipient addresses.
 The crossbar() C function contains some comment that refers
 to some similar thing, but I found it unimplemented.
         /*    
          * We expect to see something like
          * (rewrite (fc fh fu) (tc th tu)) or
          * ((address-rewrite header-rewrite) (fc fh fu) (tc th tu))
          * back from the crossbar function.
          */

- When killing previous routers/scheduler/smtpserver, should wait
  the previous process group leader to die before writing over
  the  $POSTOFFICE/.pid.KIND -file.

- Co-ordinated shutdown for the scheduler -- send a signal to it
  (SIGQUIT), and it sends out newlines to all processes still
  receiving anything from the scheduler, and shuts the feed channels
  down from the scheduler to the transporters.  Then it will spend
  some time (infinity?) to get responces from the transporters.
  When all childs are dead, it can exit.
	20-Jan-97: Sort of facility exists now..

- DSN (Delivery Status Notification) mechanism does not (yet) report
  on "DELAY".

- BUG! mailbox has a file creation failure window:
        - mailbox1 tests to see if the mailbox exists, and it does not
        - mailbox2 tests to see if the mailbox exists, and it does not
        - mailbox1 tries to do exclusive file creation (and succeeds)
        - mailbox2 tries to do exclusive file creation (and fails)
  Time in between test, and creation is milliseconds, but if system
  process scheduling hits in between, both believe to be acting in void.
  This can propably be triggered by NOT having the target file in existence,
  and sending a message with two addresses, one straight to the recipient
  mailbox, and another via some alias.  System starts TWO mailbox programs
  to feed the messages.  Try it enough times, and it will occur.
	(18 Aug 1996 -- Fixed ? By allowing 'EEXIST' return from file
	 creation, and understanding it as a result from a race above.))

- Want to have more interactivity at the scheduler status and control
  mechanisms.  Especially thinking a new two-way system where there
  can be multiple manager interfaces acting at the scheduler ``mailq''
  port issueing commands (queries), and receiving responces.
  With authentication, could do queue purges, rerouteing commands, etc.

- 'channel error' detection is partial at places;
	transporters: hold, errormail

- router/rfc822.c:  sequencer()
	Consider providing some data/function/whatever telling to
	the configuration script how many "Received:" headers there
	are so that the message can be trapped for a loop-prevention
	in the script, and not hardwired in the sequencer() code.
	(Now has a global variable that gets the count of "Received:"
	 headers, but the loop-count exceeded trap is done in the
	 same C-code without calling the scripts...)

- transporters: Truly full-scale MIME-conversion facilities are in need!

- transporters: When decoding MIME-QP the final line MAY be of
		".....=", which means there is no final NEWLINE.
	Fixed on SMTP, must fix on MAILBOX, and SM!  (4-Jan-95)
	(Prepared to do it, however only on SMTP it is fatal -- I think..)

- Configuration files, esp.   cf/aliases.cf   has controversy in it.
  Many people think it is broken (I tend to agree) - 940614/mea

- Canned error messages are abysmal -- they need more complete ways to
  configure what is told and how, whole error facility needs an overhaul
  in fact..  (See mention above about: IETF NOTARY)

- Sometimes incoming SMTP can be a hellish load, need to introduce
  a load-limited incoming SMTP acceptor (smtpserver/smtpserver.c)
  (Rayan wrote it, but never released it..)
	13-Dec-94:  It exists for Linux ....
	23-Dec-94:  Pulled bits from "top" -program.  Now it
		    exists also for Suns..

  A discussion on the ZMailer -list revealed that the acceptance blocking
  is a BIG can of worms, and that even the  BSD-sendmail has had a long
  journey along the rocky path to "get it right"...  (5-Jan-95)

  Hmm.. Perhaps we could do a `single process doing multi-stream reception ?'
  it would require fairly large rewrite of the SMTP-server..

  Also: What to do when there are more incoming SMTP sessions than the
  process can have open file descriptors ?  Two for each way of SMTP (for
  stdio library!) channel, one for each spool file in active use at the
  input phase, and one for log. (The stdio is used only for SMTP responses,
  and for spooling out the accumulated message.  Thus there SHOULD be enough
  resources for all uses -- except when the system runs out of FDs per any
  individual process..)

- Processing of several headers is questionable/lack of:
	From: <>  -- should be valid! --- now is (940626/mea)
	Return-Path: <> -- ANYTHING ACCEPTED -- header removed! (961114/mea)
		
	Generic: header wrapping within N chars (like to 80-chars
		 space of BITNET) and also infinite wide systems,
		 like News.. (transports/libta/writeheaders.c ?)

	Generic: RFC-1342 aka. non-US-ASCII chars in the headers..
		 Auto-conversion and wrapping

- On the zmailer@nic.funet.fi -list there has been also talk about
  a desire to replace the zmsh with some other language, like Scheme..
  I am not sure a lispish language is good one -- should postmasters
  be Lisp-Hackers to configure the ZMailer ?
