Known/suspected bugs/Missing Features on current Zmailer sources

- smtpserver / router:
	- more complete address processing into policytest() routines
	- smtp-server to optionally verify the MAIL FROM:<..> address
	  to be routeable -- valid MX/A existing.

- scheduler/ta:
	- Does the NOTIFY=SUCCESS work ok ?
		[2.99.49b2 - now it should]

- transports/sm/sm.c:
	- DSN handling flags ?

- 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...

- 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)

- scheduler:
	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...

- transports/sm/sm.c:
	- "localize" the destination address properly.  That is, strip
	  quotes from around a quoted destination address according to
	  the RFC822 syntax.
	- Is this always correct ?

- transports/smtp/smtp.c:
	- under some conditions the status report that the remote system
	  gives (ENHANCEDSTATUSCODES) are not brought into the proper
	  status report  (At nic:  "Mail -v @mea.tmt.tele.fi:mea@utu.fi"
	  which becomes blocked by the anti-relay policy...)
	- pipelined mode needs a recheck to the status analysis of the
	  MAIL FROM:<>, RCPT TO:<>, DATA -phase.  If the MAIL/RCPT cmds
	  gave non-ok (no RCPT gave OK), the reception of false from
	  the DATA is no surprise, and SHOULD NOT be treated as permanent
	  error even though it may present a 5XX code..
		[done? need to verify!]
	- 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..
	  (Noteing that all MX-hosts with same or larger privilege,
	   than ourselves are to be pre-removed from the list!)
	- To support RFC-1830 SMTP extension: CHUNKING

- 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() ?

- scheduler:
	- 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...

- 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

- Scheduler eats way too much memory, when some huge lists
  flow thru it -- all recipient channels/hosts PLUS the whole
  transport specifications file.  With TA's doing statistics
  logging, the scheduler should not need to keep those copies
  of the file's full TA-spec files in scheduler's core.
	4-Feb-97: Now it won't...  It is up to the transport-agents to
				   do the verbose logging on a file

- 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.

- Need to add the  sdbm ( support/sdbm/ )  in NDBM compability mode to
  the system in case the system does not have  <ndbm.h>  in it, nor
  libdbm.a -- low priotity..

- Add LDAP databases to router!
	(sendmail-8.8.x has/will get LDAP)

- '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...)

- Manuals leave a lot to desire.. Especially a good users/administrators
  manual is in need

- 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..)

- Alias processing by "newaliases" (printaliases: run_praliases)
  is "interesting" -- if sysadm wants to add an alias like:
	"Example Name": realname
  That just doesn't work..  (jeah, sure I want to use such aliases :)  )
	29-1-97: Now it works :) (2.99.46b)

- 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 ?
