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$Cambridge: exim/doc/doc-txt/NewStuff,v 1.37 2005/04/27 13:29:32 ph10 Exp $
New Features in Exim
--------------------
This file contains descriptions of new features that have been added to Exim,
but have not yet made it into the main manual (which is most conveniently
updated when there is a relatively large batch of changes). The doc/ChangeLog
file contains a listing of all changes, including bug fixes.
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/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.
TF/01 $received_time is a new expansion variable containing the time and date
as a number of seconds since the start of the Unix epoch when the
current message was received.
PH/03 There is a new value for RADIUS_LIB_TYPE that can be set in
Local/Makefile. It is RADIUSCLIENTNEW, and it requests that the new API,
in use from radiusclient 0.4.0 onwards, be used. It does not appear to be
possible to detect the different versions automatically.
PH/04 There is a new option called acl_not_smtp_mime that allows you to scan
MIME parts in non-SMTP messages. It operates in exactly the same way as
acl_smtp_mime
PH/05 It is now possible to redefine a macro within the configuration file.
The macro must have been previously defined within the configuration (or
an included file). A definition on the command line using the -D option
causes all definitions and redefinitions within the file to be ignored.
In other words, -D overrides any values that are set in the file.
Redefinition is specified by using '==' instead of '='. For example:
MAC1 = initial value
...
MAC1 == updated value
Redefinition does not alter the order in which the macros are applied to
the subsequent lines of the configuration file. It is still the same
order in which the macros were originally defined. All that changes is
the macro's value. Redefinition makes it possible to accumulate values.
For example:
MAC1 = initial value
...
MAC1 == MAC1 and something added
This can be helpful in situations where the configuration file is built
from a number of other files.
PH/06 Macros may now be defined or redefined between router, transport,
authenticator, or ACL definitions, as well as in the main part of the
configuration. They may not, however, be changed within an individual
driver or ACL, or in the local_scan, retry, or rewrite sections of the
configuration.
PH/07 $acl_verify_message is now set immediately after the failure of a
verification in an ACL, and so is available in subsequent modifiers. In
particular, the message can be preserved by coding like this:
warn !verify = sender
set acl_m0 = $acl_verify_message
Previously, $acl_verify_message was set only while expanding "message"
and "log_message" when a very denied access.
PH/08 The redirect router has two new options, sieve_useraddress and
sieve_subaddress. These are passed to a Sieve filter to specify the :user
and :subaddress parts of an address. Both options are unset by default.
However, when a Sieve filter is run, if sieve_useraddress is unset, the
entire original local part (including any prefix or suffix) is used for
:user. An unset subaddress is treated as an empty subaddress.
PH/09 Quota values can be followed by G as well as K and M.
PH/10 $message_linecount is a new variable that contains the total number of
lines in the header and body of the message. Compare $body_linecount,
which is the count for the body only. During the DATA and
content-scanning ACLs, $message_linecount contains the number of lines
received. Before delivery happens (that is, before filters, routers, and
transports run) the count is increased to include the Received: header
line that Exim standardly adds, and also any other header lines that are
added by ACLs. The blank line that separates the message header from the
body is not counted. Here is an example of the use of this variable in a
DATA ACL:
deny message = Too many lines in message header
condition = \
${if <{250}{${eval: $message_linecount - $body_linecount}}}
In the MAIL and RCPT ACLs, the value is zero because at that stage the
message has not yet been received.
Version 4.50
------------
The documentation is up-to-date for the 4.50 release.
****
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