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Sieve implementation for Dovecot v1.2
Sieve is a machine language specifically tailored for internet message
filtering. This package compiles into a Sieve plugin for the Dovecot local
delivery agent called Deliver. The plugin adds Sieve filtering support to the
delivery process.
Previously, the same functionality was provided by the cmusieve plugin for
Dovecot. This old plugin is based on the CMU Sieve implementation included with
the Cyrus project. This new package provides a complete rewrite of the Sieve
engine integrating it tightly with Dovecot. The actual execution of the Sieve
actions is based on the original cmusieve plugin, but only on the code added to
The main reason for rewriting the Sieve engine is to provide more reliable
script execution and to provide better error messages to users and system
administrators. Also, since the Sieve language evolves quickly, with new
language extensions published every year, the aim is to provide support for
quickly extending the engine with new features.
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* Well-structured 3-stage compiler:
Uses dovecot framework and avoids using lex/yacc. Compiler doesn't bail on
first error, but tries to find more. Produced errors are aimed to be useful
and generally user-comprehensible. Things like 'Generic error' are a nuisance
of the past.
* Highly extendable with new sieve capabilities:
This keeps the possibility of plugins in mind. It should eventually provide
the necessary infrastructure for at least all currently known (proposed)
extensions. The goal is to keep the extension interface provided by sieve
engine as generic as possible, i.e. without explicit support for specific
extensions. New similar extensions can then use the same interface methods
without changes to the sieve engine code. If an extension is not loaded using
the require command, the compiler truly does not know of its existance.
* Supports almost all extensions provided by the original CMUSieve plugin:
Currently only the notify extension is missing. In addition, it has support
for the new and very useful variables extension (see next section).
* Supported by ManageSieve service:
This Sieve implementation is supported by the ManageSieve implementation for
Dovecot v1.2. Therefore, ManageSieve support can be added to Dovecot for the
new Sieve plugin just as for the cmusieve plugin.
* Testsuite included:
This package includes a testsuite to automatically asses whether the compiled
sieve engine works correctly. The testsuite is an extension to the Sieve
language and is therefore easily extended with new tests. Currently, the
testsuite is limited to testing script processing. The performed actions are
not tested automatically yet.
Implementation Status
---------------------
The the core of the language (as specified in RFC 5228) is fully supported. In
addition to that, this Sieve implementation features various extensions. The
following list outlines the implementation status of each supported extension:
Base specification (RFC5228):
fileinto: full
reject: full (without Dovecot LMTP currently no refuse support)
envelope: full
encoded-character: full
Other RFCs/drafts:
subaddress: mostly full; not configurable
comparator-i;ascii-numeric: full
relational: full
copy: full
regex: mostly full; but suboptimal and no UTF-8
body: mostly full, but text body-transform implementation is simple
include: mostly full; needs some more work (no external binaries)
vacation: mostly full; no support for required References header and
imapflags: full
variables: mostly full; currently no support for future namespaces
All implemented extensions are like the engine itself currently experimental.
A status of 'full' does not necessarily mean that the extension is bug-free or
even fully RFC-compliant.
Many more extensions to the language exist. Not all of these extensions are
useful for Dovecot in particular, but many of them are. Currently, the author
has taken notice of the following extensions:
editheader: planned, needs additional support from Dovecot though.
mimeloop: planned
These extensions will be added as soon as the necessary infrastructure is
available. Extensions already supported by cmusieve have priority, meaning that
notify is next in line.
Compiling and Configuring
-------------------------
Stephan Bosch
committed
Refer to INSTALL file.
Using
-----
The main purpose of this package is to replace the existing cmusieve plugin that
is currently available for Dovecot's deliver. With this respect it is currently
not very different from the cmusieve plugin implementation.
Unlike cmusieve, this sieve module logs runtime errors to <scriptfile>.log if
it can and not <scriptfile>.err. It appends new timestamped log entries to the
end of the logfile. If the log grows too large (currently > 10kB), the logfile
is rotated to <scriptfile>.log.0 and <scriptfile>.log starts out empty again.
The cmusieve plugin compiled the script into a file with an appended c, e.g.
'test.sievec'. This new implementation recognizes scripts to have the .sieve
extension. The binary is (by default) written to a file with extension .svbin.
This means that the default .dovecot.sieve is compiled into .dovecot.svbin.
Included scripts are currently always compiled into the main binary, meaning
that no other files are written and no permission to do so is necessary for the
global script directories.
To test the sieve engine outside deliver it is useful to execute the binaries
that exist in the src/sieve-bin/ directory of this package. After installation,
these scripts are available in the dovecot lib directory. The following commands
are available:
Compiles the script and produces a sieve binary. However, when the -d option is
provided, a code dump is written to the output file. When the output file is '-'
the dump output is written to stdout (only if -d is specified).
--
sieved <bin-file> [<dump-file>]
Reads a sieve binary and produces a code dump. The optional dump-file parameter
provides the means to specify a file to which the dump is to be written.
Otherwise, the dump is printed to stdout.
sieve-test [-r <recipient address>][-s <envelope sender>]
[-m <mailbox>][-d <dump filename>][-c][-t] <scriptfile> <mailfile>
Reads mail message from the specified mailfile and executes the specified sieve
script to produce a verdict. This prints a list of actions that would
have been performed on this message.
-r envelope recipient address
-s envelope sender
-m the mailbox where the keep action should store
-d causes a dump of the generated code to be written to the specified
file. Using - as filename causes the dump to be written to stdout
-c force compilation (ignore any existing binary)
-t enable trace simple debugging; prints all encountered byte code
instructions on stdout.
--
sieve-exec
Currently undocumented (will be merged with sieve-test).
--
Various example scripts are bundled in the directory 'examples'.
Known issues
------------
Most open issues are outlined in the TODO file. The more generic ones are (re-)
listed here:
- Compile errors are sometimes a bit obscure and long. This needs work.
Suggestions for improvement are welcome.
Authors
-------
Refer to AUTHORS file.
Contact Info
------------
Stephan Bosch <stephan at rename-it dot nl>
IRC: Freenode, #dovecot, S[r]us
Please use the Dovecot mailing list <dovecot at dovecot.org> for questions about
this package. You can post to the list without subscribing, the mail then waits
in a moderator queue for a while. See http://dovecot.org/mailinglists.html