docs/diploma

annotate thesis/tex/4-MasqmailsFuture.tex @ 137:c60b164bfd3c

rearranging of ch04
author meillo@marmaro.de
date Wed, 10 Dec 2008 21:12:09 +0100
parents 653ff21b89be
children 002fd18820cc
rev   line source
meillo@109 1 \chapter{\masqmail's present and future}
meillo@93 2
meillo@137 3 \section{Existing code base}
meillo@137 4 Here regarded is version 0.2.21 of \masqmail. This is the last version released by \person{Oliver Kurth}, and the basis for my thesis.
meillo@93 5
meillo@137 6 \subsubsection*{Features}
meillo@93 7
meillo@137 8 \masqmail\ accepts mail on the command line and via \SMTP. Mail queueing and alias expansion is supported. \masqmail\ is able to deliver mail to local mailboxes (in \name{mbox} or \name{maildir} format) or pass it to a \name{mail delivery agent} (like \name{procmail}). Mail destinated to remote locations is sent using \SMTP.
meillo@93 9
meillo@137 10 Outgoing \SMTP\ connections feature \SMTP-\NAME{AUTH} and \SMTP-after-\NAME{POP} authentication, but incoming \SMTP\ does not.
meillo@137 11 %todo: what about SSL/TLS encryption?
meillo@93 12
meillo@137 13 The \masqmail\ executable can be called under various names for sendmail-compatibility reasons. This is organized by symbolic links with different names pointing to the \masqmail\ executable. The \sendmail\ names are \path{/usr/lib/sendmail} and \path{/usr/sbin/sendmail} because many programs expect the \mta\ to be located there. Further more \sendmail\ supports calling it with a different name instead of supplying command line arguments. The best known of this shortcuts is \path{mailq}, which is equivilent to calling it with the argument \verb+-bq+. \masqmail\ recognizes the names \path{mailq}, \path{smtpd}, \path{mailrm}, \path{runq}, \path{rmail}, and \path{in.smtpd}. The first two are inspired by \sendmail. Not implemented is the name \path{newaliases} because \masqmail\ does not generate binary representations of the alias file.\footnote{A shell script located named \path{newaliases}, that invokes \texttt{masqmail -bi}, can provide the command to satisfy other software needing it.} \path{hoststat} and \path{purgestat} are missing for sendmail-compatibility.
meillo@109 14 %masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd
meillo@109 15 %sendmail: hoststat, mailq, newaliases, purgestat, smtpd
meillo@109 16
meillo@137 17 Additional to the \mta\ job, \masqmail\ also offers mail retrieval services with being a \NAME{POP3} client. It can fetch mail from different remote locations, dependent on the active online route.
meillo@109 18
meillo@137 19
meillo@137 20
meillo@137 21 \subsubsection*{The code}
meillo@137 22
meillo@137 23 \masqmail\ is written in the C programming language. The program, as of version 0.2.21, consists of 34 source code and eight header files, containing about 9,000 lines of code\footnote{Measured with \name{sloccount} by David A.\ Wheeler.}. Additionally, it includes a \name{base64} implementation (about 300 lines) and \name{md5} code (about 150 lines). For systems that do not provide \name{libident}, this library is distributed as well (circa 600 lines); an available shared library however has higher precedence in linking.
meillo@137 24
meillo@137 25 The only mandatory dependency is \name{glib}---a cross-platform software utility library, originated in the \NAME{GTK+} project. It provides safer replacements for many standard library functions. It also offers handy data containers, easy-to-use implementations of data structures, and much more.
meillo@137 26
meillo@109 27
meillo@109 28 With \masqmail\ comes the small tool \path{mservdetect}; it helps setting up a configuration that uses the \name{mserver} system to detect the online state. Two other binaries get compiled for testing purposes: \path{readtest} and \path{smtpsend}. All three programms use \masqmail\ source code; they only add a file with a \verb+main()+ function each.
meillo@109 29
meillo@93 30
meillo@137 31 \masqmail\ does not provide an interface to plug in modules with additional functionality. There exists no add-on or module system. The code is only separated by function to the various source files. Some functional parts can be included or excluded by defining symbols. Adding maildir support at compile time, means giving the option \verb+--enable-maildir+ to the \path{configure} call. This preserves the concerning code to get removed by the preprocessor. Unfortunately the \verb+#ifdef+s are scattered through all the source, leading to a FIXME(holperig) code base.
meillo@93 32
meillo@132 33
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meillo@137 37 \section{Directions to go}
meillo@132 38
meillo@132 39 << plans to get masqmail more popular again (if that is the goal) >> %FIXME
meillo@132 40
meillo@132 41
meillo@137 42 \subsection{\masqmail\ in five years}
meillo@137 43
meillo@137 44 Now how could \masqmail\ be like in, say, five years?
meillo@137 45
meillo@137 46 << requirements >> %FIXME
meillo@137 47
meillo@137 48 << which parts to do >> %FIXME
meillo@137 49
meillo@137 50 << how to make masqmail future-safe >> %FIXME
meillo@137 51
meillo@137 52 << how to advertise masqmail >> %FIXME
meillo@137 53
meillo@137 54 << why is it worth to revive masqmail? >> %FIXME
meillo@137 55
meillo@137 56
meillo@137 57
meillo@137 58 << concrete decisions based on results of the last 2 chapters >> %FIXME
meillo@137 59
meillo@137 60
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meillo@137 62
meillo@132 63 \subsection{Architecture}
meillo@132 64
meillo@132 65 << architecture diagram >>
meillo@132 66
meillo@132 67 (ssl) -> msg-in (local or remote protocol handlers) -> spam-filter (and more) -> queue -> msg-out (local-delivery by MDA, or remote-protocol-handlers) -> (ssl)
meillo@132 68
meillo@132 69 A design from scratch?
meillo@132 70
meillo@132 71 << what would be needed (effort) >> %FIXME
meillo@132 72
meillo@132 73 << would one create it at all? >> %FIXME
meillo@132 74
meillo@132 75 << should it be done? >> %FIXME
meillo@132 76
meillo@132 77
meillo@132 78
meillo@132 79 \subsection{local mail delivery}
meillo@132 80 But for example delivery of mail to local users is \emph{not} what \mta{}s should care about, although most \MTA\ are able to deliver mail, and many do. (\name{mail delivery agents}, like \name{procmail} and \name{maildrop}, are the right programs for this job.)
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meillo@132 83
meillo@132 84 \subsection{various protocols}
meillo@132 85 protocols like \NAME{SMTP} and \NAME{UUCP}, between which mail is transferred.\footnote{\sendmail{}'s initial purpose was moving mail between \NAME{UUCP}, \NAME{SMTP}, and \name{Berknet}.}
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meillo@132 92 http://fanf.livejournal.com/50917.html %how not to design an mta - the sendmail command
meillo@132 93 http://fanf.livejournal.com/51349.html %how not to design an mta - partitioning for security
meillo@132 94 http://fanf.livejournal.com/61132.html %how not to design an mta - local delivery
meillo@132 95 http://fanf.livejournal.com/64941.html %how not to design an mta - spool file format
meillo@132 96 http://fanf.livejournal.com/65203.html %how not to design an mta - spool file logistics
meillo@132 97 http://fanf.livejournal.com/65911.html %how not to design an mta - more about log-structured MTA queues
meillo@132 98 http://fanf.livejournal.com/67297.html %how not to design an mta - more log-structured MTA queues
meillo@132 99 http://fanf.livejournal.com/70432.html %how not to design an mta - address verification
meillo@132 100 http://fanf.livejournal.com/72258.html %how not to design an mta - content scanning
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meillo@99 112
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meillo@93 116 \section{Work to do}
meillo@93 117
meillo@99 118 << which parts to take out and do within the thesis >> %FIXME
meillo@93 119
meillo@133 120