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comparison thesis/tex/1-Introduction.tex @ 238:d60e5843db7f
moved text from ch04 to ch01
| author | meillo@marmaro.de |
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| date | Sat, 10 Jan 2009 22:26:29 +0100 |
| parents | c5f44219bc5d |
| children | da83360f8442 |
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| 122 \section{Existing code base} | |
| 123 | |
| 124 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. | |
| 125 | |
| 126 | |
| 127 \subsubsection*{The source code} | |
| 128 | |
| 129 \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 has higher precedence in linking, though. | |
| 130 | |
| 131 The only mandatory dependency is \name{glib}---a cross-platform software utility library, originated in the \NAME{GTK+} project. It provides safe replacements for many standard library functions, especially for the string functions. It also offers handy data containers, easy-to-use implementations of data structures, and much more. | |
| 132 | |
| 133 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 programs use \masqmail\ source code; they only add a file with a \verb+main()+ function each. | |
| 134 | |
| 135 \masqmail\ lacks 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 at compile time. Adding maildir support, 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 code that is hard to read. | |
| 136 %fixme: refer to ifdef-considered-harmful ? | |
| 137 | |
| 138 | |
| 139 | |
| 140 \subsubsection*{Features} | |
| 141 \label{sec:masqmail-features} | |
| 142 | |
| 143 \masqmail\ supports two channels for incoming mail: (1) Standard input, used when \path{masqmail} is executed on the command line and (2) a \NAME{TCP} socket, used by local or remote clients that talk \SMTP. The outgoing channels for mail are: (1) direct delivery to local mailboxes (in \name{mbox} or \name{maildir} format), (2) local pipes to pass mail to a program (e.g.\ gateways to \NAME{UUCP}, gateways to fax, or \NAME{MDA}s), and (3) \NAME{TCP} sockets to transfer mail to other \MTA{}s using the \SMTP\ protocol. | |
| 144 | |
| 145 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 allows encrypted communication through a gateway application like \name{openssl}. | |
| 146 | |
| 147 Mail queuing and alias expansion is both supported. | |
| 148 | |
| 149 \masqmail\ focuses on non-permanent online connections, thus a concept of online routes is used. One may configure any number of routes to send mail. Each route can have criteria to determine if some message is allowed to be sent over it. This concept is explained in section \ref{sec:masqmail-routes} in detail. Mail to destinations outside the local network gets queued until an online connections is available. | |
| 150 | |
| 151 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 equivalent to calling it with the argument \verb+-bq+. \masqmail\ recognizes the shortcuts \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 shortcut \path{newaliases} because \masqmail\ does not generate binary representations of the alias file.\footnote{A shell script 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 complete sendmail-compatibility. | |
| 152 %masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd | |
| 153 %sendmail: hoststat, mailq, newaliases, purgestat, smtpd | |
| 154 | |
| 155 Additional to the \mta\ job, \masqmail\ also offers mail retrieval services by being a \NAME{POP3} client. It can fetch mail from different remote locations, dependent on the active online connection. | |
| 156 | |
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| 158 | |
| 159 | |
| 160 | |
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| 163 | |
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| 165 | |
| 122 \subsubsection*{What makes it special} | 166 \subsubsection*{What makes it special} |
| 123 | 167 |
| 124 As main advantage, \masqmail\ makes it easy to set up an \MTA\ on workstations or notebooks without the need to do complex configuration or to be an mail server expert. | 168 As main advantage, \masqmail\ makes it easy to set up an \MTA\ on workstations or notebooks without the need to do complex configuration or to be an mail server expert. |
| 125 | 169 |
| 126 Workstations use %FIXME | 170 Workstations use %FIXME |