-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.27 2005/03/08 11:38:21 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.29 2005/03/22 15:02:34 ph10 Exp $
New Features in Exim
--------------------
Version 4.51
------------
-PH/01. The format in which GnuTLS parameters are written to the gnutls-param
- file in the spool directory has been changed. This change has been made
- to alleviate problems that some people had with the generation of the
- parameters by Exim when /dev/random was exhausted. In this situation,
- Exim would hang until /dev/random acquired some more entropy.
-
- The new code exports and imports the DH and RSA parameters in PEM
- format. This means that the parameters can be generated externally using
- the certtool command that is part of GnuTLS.
-
- To replace the parameters with new ones, instead of deleting the file
- and letting Exim re-create it, you can generate new parameters using
- certtool and, when this has been done, replace Exim's cache file by
- renaming. The relevant commands are something like this:
-
- # rm -f new.params
- # touch new.params
- # chown exim:exim new.params
- # chmod 0400 new.params
- # certtool --generate-privkey --bits 512 >new.params
- # echo "" >>new.params
- # certtool --generate-dh-params --bits 1024 >> new.params
- # mv new.params params
-
- If Exim never has to generate the parameters itself, the possibility of
- stalling is removed.
+PH/01 The format in which GnuTLS parameters are written to the gnutls-param
+ file in the spool directory has been changed. This change has been made
+ to alleviate problems that some people had with the generation of the
+ parameters by Exim when /dev/random was exhausted. In this situation,
+ Exim would hang until /dev/random acquired some more entropy.
+
+ The new code exports and imports the DH and RSA parameters in PEM
+ format. This means that the parameters can be generated externally using
+ the certtool command that is part of GnuTLS.
+
+ To replace the parameters with new ones, instead of deleting the file
+ and letting Exim re-create it, you can generate new parameters using
+ certtool and, when this has been done, replace Exim's cache file by
+ renaming. The relevant commands are something like this:
+
+ # rm -f new.params
+ # touch new.params
+ # chown exim:exim new.params
+ # chmod 0400 new.params
+ # certtool --generate-privkey --bits 512 >new.params
+ # echo "" >>new.params
+ # certtool --generate-dh-params --bits 1024 >> new.params
+ # mv new.params params
+
+ If Exim never has to generate the parameters itself, the possibility of
+ stalling is removed.
+
+PH/02 A new expansion item for dynamically loading and calling a locally-
+ written C function is now provided, if Exim is compiled with
+
+ EXPAND_DLFUNC=yes
+
+ set in Local/Makefile. The facility is not included by default (a
+ suitable error is given if you try to use it when it is not there.)
+
+ If you enable EXPAND_DLFUNC, you should also be aware of the new redirect
+ router option forbid_filter_dlfunc. If you have unprivileged users on
+ your system who are permitted to create filter files, you might want to
+ set forbid_filter_dlfunc=true in the appropriate router, to stop them
+ using ${dlfunc to run code within Exim.
+
+ You load and call an external function like this:
+
+ ${dlfunc{/some/file}{function}{arg1}{arg2}...}
+
+ Once loaded, Exim remembers the dynamically loaded object so that it
+ doesn't reload the same object file in the same Exim process (but of
+ course Exim does start new processes frequently).
+
+ There may be from zero to eight arguments to the function. When compiling
+ a local function that is to be called in this way, local_scan.h should be
+ included. The Exim variables and functions that are defined by that API
+ are also available for dynamically loaded functions. The function itself
+ must have the following type:
+
+ int dlfunction(uschar **yield, int argc, uschar *argv[])
+
+ Where "uschar" is a typedef for "unsigned char" in local_scan.h. The
+ function should return one of the following values:
+
+ OK Success. The string that is placed in "yield" is put into
+ the expanded string that is being built.
+
+ FAIL A non-forced expansion failure occurs, with the error
+ message taken from "yield", if it is set.
+
+ FAIL_FORCED A forced expansion failure occurs, with the error message
+ taken from "yield" if it is set.
+
+ ERROR Same as FAIL, except that a panic log entry is written.
+
+ When compiling a function that is to be used in this way with gcc,
+ you need to add -shared to the gcc command. Also, in the Exim build-time
+ configuration, you must add -export-dynamic to EXTRALIBS.
Version 4.50
git://git.exim.org / exim.git / blobdiff