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diff --git a/README_FILES/PCRE_README b/README_FILES/PCRE_README new file mode 100644 index 0000000..788859a --- /dev/null +++ b/README_FILES/PCRE_README @@ -0,0 +1,69 @@ +PPoossttffiixx PPCCRREE SSuuppppoorrtt + +------------------------------------------------------------------------------- + +PPCCRREE ((PPeerrll CCoommppaattiibbllee RReegguullaarr EExxpprreessssiioonnss)) mmaapp ssuuppppoorrtt + +The optional "pcre" map type allows you to specify regular expressions with the +PERL style notation such as \s for space and \S for non-space. The main +benefit, however, is that pcre lookups are often faster than regexp lookups. +This is because the pcre implementation is often more efficient than the POSIX +regular expression implementation that you find on many systems. + +A description of how to use pcre tables, including examples, is given in the +pcre_table(5) manual page. Information about PCRE itself can be found at http:/ +/www.pcre.org/. + +BBuuiillddiinngg PPoossttffiixx wwiitthh PPCCRREE ssuuppppoorrtt + +These instructions assume that you build Postfix from source code as described +in the INSTALL document. Some modification may be required if you build Postfix +from a vendor-specific source package. + +Note: to use pcre with Debian GNU/Linux's Postfix, all you need is to install +the postfix-pcre package and you're done. There is no need to recompile +Postfix. + +In some future, Postfix will have a plug-in interface for adding map types. +Until then, you need to compile PCRE support into Postfix. + +First of all, you need the PCRE library (Perl Compatible Regular Expressions), +which can be obtained from: + + ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/. + +NOTE: pcre versions prior to 2.06 cannot be used. + +In order to build Postfix with PCRE support you need to add -DHAS_PCRE and a - +I option for the PCRE include file to CCARGS, and add the path to the PCRE +library to AUXLIBS_PCRE, for example: + + make -f Makefile.init makefiles \ + "CCARGS=-DHAS_PCRE `pcre-config --cflags`" \ + "AUXLIBS_PCRE=`pcre-config --libs`" + +Postfix versions before 3.0 use AUXLIBS instead of AUXLIBS_PCRE. With Postfix +3.0 and later, the old AUXLIBS variable still supports building a statically- +loaded PCRE database client, but only the new AUXLIBS_PCRE variable supports +building a dynamically-loaded or statically-loaded PCRE database client. + + Failure to use the AUXLIBS_PCRE variable will defeat the purpose of dynamic + database client loading. Every Postfix executable file will have PCRE + library dependencies. And that was exactly what dynamic database client + loading was meant to avoid. + +TThhiinnggss ttoo kknnooww + + * When Postfix searches a pcre: or regexp: lookup table, each pattern is + applied to the entire input string. Depending on the application, that + string is an entire client hostname, an entire client IP address, or an + entire mail address. Thus, no parent domain or parent network search is + done, "user@domain" mail addresses are not broken up into their user and + domain constituent parts, and "user+foo" is not broken up into user and + foo. + + * Regular expression tables such as pcre: or regexp: are not allowed to do + $number substitution in lookup results that can be security sensitive: + currently, that restriction applies to the local aliases(5) database or the + virtual(8) delivery agent tables. + |