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1 \chapter{\masqmail's present and future}
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2
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3 \section{Existing code base}
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4 Here regarded is version 0.2.21 of \masqmail. This is the last version released by Oliver \person{Kurth}, and the basis for my thesis.
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5
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6
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7 \subsubsection*{Features}
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8
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9 \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\ or can be piped to commands, being gatesways to \NAME{UUCP} or \NAME{FAX} for example.
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10
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11 Outgoing \SMTP\ connections feature \SMTP-\NAME{AUTH} and \SMTP-after-\NAME{POP} authentication, but incoming connections do not. Using wrappers for outgoing connections is supported. This offers a two way communication through a wrapper application like \name{openssl}.
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12 %todo: what about SSL/TLS encryption?
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13
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14 \masqmail\ focuses on non-permanent online connections, thus a concept of online routes is used. One may configure any amount of routes to send mail. Each route can have criterias, like matching \texttt{From:} or \texttt{To:} headers, to determine if mail is allowed to be sent using it. Mail to destinations outside the local net gets queued until \masqmail\ is informed about the existance of a online connection.
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15
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16 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.
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17 %masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd
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18 %sendmail: hoststat, mailq, newaliases, purgestat, smtpd
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19
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20 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.
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21
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22
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23
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24 \subsubsection*{The code}
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25
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26 \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.
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27
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28 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.
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29
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30
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31 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.
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32
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33
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34 \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.
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35
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36
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37
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38
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39
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40 \section{Directions to go}
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41
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42 << plans to get masqmail more popular again (if that is the goal) >>
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43
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44
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45 \subsection{\masqmail\ in five years}
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46
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47 Now how could \masqmail\ be like in, say, five years?
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48
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49 << requirements >>
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50
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51 << which parts to do >>
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52
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53 << how to make masqmail future-safe >>
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54
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55 << how to advertise masqmail >>
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56
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57 << why is it worth to revive masqmail? >>
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58
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59
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60 << short term goals --- long term goals >>
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61
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62 << concrete decisions based on results of the last 2 chapters >>
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63
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64
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65
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66
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67 \subsection{Architecture}
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68
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69 << architecture diagram >>
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70
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71 (ssl) -> msg-in (local or remote protocol handlers) -> spam-filter (and more) -> queue -> msg-out (local-delivery by MDA, or remote-protocol-handlers) -> (ssl)
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72
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73 A design from scratch?
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74
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75 << what would be needed (effort) >>
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76
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77 << would one create it at all? >>
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78
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79 << should it be done? >>
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80
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81
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82
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83 \subsection{local mail delivery}
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84 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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85
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86
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87
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88 \subsection{various protocols}
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89 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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90
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91
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92
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93
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94
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95
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96 http://fanf.livejournal.com/50917.html %how not to design an mta - the sendmail command
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97 http://fanf.livejournal.com/51349.html %how not to design an mta - partitioning for security
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98 http://fanf.livejournal.com/61132.html %how not to design an mta - local delivery
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99 http://fanf.livejournal.com/64941.html %how not to design an mta - spool file format
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100 http://fanf.livejournal.com/65203.html %how not to design an mta - spool file logistics
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101 http://fanf.livejournal.com/65911.html %how not to design an mta - more about log-structured MTA queues
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102 http://fanf.livejournal.com/67297.html %how not to design an mta - more log-structured MTA queues
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103 http://fanf.livejournal.com/70432.html %how not to design an mta - address verification
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104 http://fanf.livejournal.com/72258.html %how not to design an mta - content scanning
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105
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106
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107
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119
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120 \section{Work to do}
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121
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122 << which parts to take out and do within the thesis >>
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123
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124
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