Tidy up "make" output along the lines of a 2.6 kernel make (just a short
[exim.git] / doc / doc-txt / NewStuff
c1ac6996 1$Cambridge: exim/doc/doc-txt/NewStuff,v 1.41 2005/05/17 09:53:34 ph10 Exp $
3New Features in Exim
6This file contains descriptions of new features that have been added to Exim,
7but have not yet made it into the main manual (which is most conveniently
8updated when there is a relatively large batch of changes). The doc/ChangeLog
9file contains a listing of all changes, including bug fixes.
12Exim version 4.52
15TF/01 Support for checking Client SMTP Authorization has been added. CSA is a
16 system which allows a site to advertise which machines are and are not
17 permitted to send email. This is done by placing special SRV records in
18 the DNS, which are looked up using the client's HELO domain. At this
19 time CSA is still an Internet-Draft.
21 Client SMTP Authorization checks are performed by the ACL condition
22 verify=csa. This will fail if the client is not authorized. If there is
23 a DNS problem, or if no valid CSA SRV record is found, or if the client
24 is authorized, the condition succeeds. These three cases can be
25 distinguished using the expansion variable $csa_status, which can take
26 one of the values "fail", "defer", "unknown", or "ok". The condition
27 does not itself defer because that would be likely to cause problems
28 for legitimate email.
30 The error messages produced by the CSA code include slightly more
31 detail. If $csa_status is "defer" this may be because of problems
32 looking up the CSA SRV record, or problems looking up the CSA target
33 address record. There are four reasons for $csa_status being "fail":
34 the client's host name is explicitly not authorized; the client's IP
35 address does not match any of the CSA target IP addresses; the client's
36 host name is authorized but it has no valid target IP addresses (e.g.
37 the target's addresses are IPv6 and the client is using IPv4); or the
38 client's host name has no CSA SRV record but a parent domain has
39 asserted that all subdomains must be explicitly authorized.
41 The verify=csa condition can take an argument which is the domain to
42 use for the DNS query. The default is verify=csa/$sender_helo_name.
44 This implementation includes an extension to CSA. If the query domain
45 is an address literal such as [], or if it is a bare IP
46 address, Exim will search for CSA SRV records in the reverse DNS as if
47 the HELO domain was e.g. Therefore it is
48 meaningful to say, for example, verify=csa/$sender_host_address - in
49 fact, this is the check that Exim performs if the client does not say
50 HELO. This extension can be turned off by setting the main
51 configuration option dns_csa_use_reverse = false.
53 If a CSA SRV record is not found for the domain itself, then a search
54 is performed through its parent domains for a record which might be
55 making assertions about subdomains. The maximum depth of this search is
56 limited using the main configuration option dns_csa_search_limit, which
57 takes the value 5 by default. Exim does not look for CSA SRV records in
58 a top level domain, so the default settings handle HELO domains as long
59 as seven (hostname.five.four.three.two.one.com) which encompasses the
60 vast majority of legitimate HELO domains.
62 The dnsdb lookup also has support for CSA. Although dnsdb already
63 supports SRV lookups, this is not sufficient because of the extra
64 parent domain search behaviour of CSA, and (as with PTR lookups)
65 dnsdb also turns IP addresses into lookups in the reverse DNS space.
66 The result of ${lookup dnsdb {csa=$sender_helo_name} } has two
67 space-separated fields: an authorization code and a target host name.
68 The authorization code can be "Y" for yes, "N" for no, "X" for explicit
69 authorization required but absent, or "?" for unknown.
71PH/01 The amount of output produced by the "make" process has been reduced,
72 because the compile lines are often rather long, making it all pretty
73 unreadable. The new style is along the lines of the 2.6 Linux kernel:
74 just a short line for each module that is being compiled or linked.
75 However, it is still possible to get the full output, by calling "make"
76 like this:
78 FULLECHO='' make -e
80 The value of FULLECHO defaults to "@", the flag character that suppresses
81 command reflection in "make". When you ask for the full output, it is
82 given in addition to the the short output.
e5a9dba6 84
85Version 4.51
88PH/01 The format in which GnuTLS parameters are written to the gnutls-param
89 file in the spool directory has been changed. This change has been made
90 to alleviate problems that some people had with the generation of the
91 parameters by Exim when /dev/random was exhausted. In this situation,
92 Exim would hang until /dev/random acquired some more entropy.
94 The new code exports and imports the DH and RSA parameters in PEM
95 format. This means that the parameters can be generated externally using
96 the certtool command that is part of GnuTLS.
98 To replace the parameters with new ones, instead of deleting the file
99 and letting Exim re-create it, you can generate new parameters using
100 certtool and, when this has been done, replace Exim's cache file by
101 renaming. The relevant commands are something like this:
103 # rm -f new.params
104 # touch new.params
105 # chown exim:exim new.params
106 # chmod 0400 new.params
107 # certtool --generate-privkey --bits 512 >new.params
108 # echo "" >>new.params
109 # certtool --generate-dh-params --bits 1024 >> new.params
110 # mv new.params params
112 If Exim never has to generate the parameters itself, the possibility of
113 stalling is removed.
115PH/02 A new expansion item for dynamically loading and calling a locally-
116 written C function is now provided, if Exim is compiled with
120 set in Local/Makefile. The facility is not included by default (a
121 suitable error is given if you try to use it when it is not there.)
123 If you enable EXPAND_DLFUNC, you should also be aware of the new redirect
124 router option forbid_filter_dlfunc. If you have unprivileged users on
125 your system who are permitted to create filter files, you might want to
126 set forbid_filter_dlfunc=true in the appropriate router, to stop them
127 using ${dlfunc to run code within Exim.
129 You load and call an external function like this:
131 ${dlfunc{/some/file}{function}{arg1}{arg2}...}
133 Once loaded, Exim remembers the dynamically loaded object so that it
134 doesn't reload the same object file in the same Exim process (but of
135 course Exim does start new processes frequently).
137 There may be from zero to eight arguments to the function. When compiling
138 a local function that is to be called in this way, local_scan.h should be
139 included. The Exim variables and functions that are defined by that API
140 are also available for dynamically loaded functions. The function itself
141 must have the following type:
143 int dlfunction(uschar **yield, int argc, uschar *argv[])
145 Where "uschar" is a typedef for "unsigned char" in local_scan.h. The
146 function should return one of the following values:
148 OK Success. The string that is placed in "yield" is put into
149 the expanded string that is being built.
151 FAIL A non-forced expansion failure occurs, with the error
152 message taken from "yield", if it is set.
154 FAIL_FORCED A forced expansion failure occurs, with the error message
155 taken from "yield" if it is set.
157 ERROR Same as FAIL, except that a panic log entry is written.
159 When compiling a function that is to be used in this way with gcc,
160 you need to add -shared to the gcc command. Also, in the Exim build-time
161 configuration, you must add -export-dynamic to EXTRALIBS.
b5aea5e1 162
163TF/01 $received_time is a new expansion variable containing the time and date
164 as a number of seconds since the start of the Unix epoch when the
165 current message was received.
b5aea5e1 166
167PH/03 There is a new value for RADIUS_LIB_TYPE that can be set in
168 Local/Makefile. It is RADIUSCLIENTNEW, and it requests that the new API,
169 in use from radiusclient 0.4.0 onwards, be used. It does not appear to be
170 possible to detect the different versions automatically.
172PH/04 There is a new option called acl_not_smtp_mime that allows you to scan
173 MIME parts in non-SMTP messages. It operates in exactly the same way as
174 acl_smtp_mime
176PH/05 It is now possible to redefine a macro within the configuration file.
177 The macro must have been previously defined within the configuration (or
178 an included file). A definition on the command line using the -D option
179 causes all definitions and redefinitions within the file to be ignored.
180 In other words, -D overrides any values that are set in the file.
181 Redefinition is specified by using '==' instead of '='. For example:
183 MAC1 = initial value
184 ...
185 MAC1 == updated value
187 Redefinition does not alter the order in which the macros are applied to
188 the subsequent lines of the configuration file. It is still the same
189 order in which the macros were originally defined. All that changes is
190 the macro's value. Redefinition makes it possible to accumulate values.
191 For example:
193 MAC1 = initial value
194 ...
195 MAC1 == MAC1 and something added
197 This can be helpful in situations where the configuration file is built
198 from a number of other files.
200PH/06 Macros may now be defined or redefined between router, transport,
201 authenticator, or ACL definitions, as well as in the main part of the
202 configuration. They may not, however, be changed within an individual
203 driver or ACL, or in the local_scan, retry, or rewrite sections of the
204 configuration.
206PH/07 $acl_verify_message is now set immediately after the failure of a
207 verification in an ACL, and so is available in subsequent modifiers. In
208 particular, the message can be preserved by coding like this:
210 warn !verify = sender
211 set acl_m0 = $acl_verify_message
213 Previously, $acl_verify_message was set only while expanding "message"
214 and "log_message" when a very denied access.
216PH/08 The redirect router has two new options, sieve_useraddress and
217 sieve_subaddress. These are passed to a Sieve filter to specify the :user
218 and :subaddress parts of an address. Both options are unset by default.
219 However, when a Sieve filter is run, if sieve_useraddress is unset, the
220 entire original local part (including any prefix or suffix) is used for
221 :user. An unset subaddress is treated as an empty subaddress.
475fe28a 222
223PH/09 Quota values can be followed by G as well as K and M.
225PH/10 $message_linecount is a new variable that contains the total number of
226 lines in the header and body of the message. Compare $body_linecount,
227 which is the count for the body only. During the DATA and
228 content-scanning ACLs, $message_linecount contains the number of lines
229 received. Before delivery happens (that is, before filters, routers, and
230 transports run) the count is increased to include the Received: header
231 line that Exim standardly adds, and also any other header lines that are
232 added by ACLs. The blank line that separates the message header from the
233 body is not counted. Here is an example of the use of this variable in a
236 deny message = Too many lines in message header
237 condition = \
238 ${if <{250}{${eval: $message_linecount - $body_linecount}}}
240 In the MAIL and RCPT ACLs, the value is zero because at that stage the
241 message has not yet been received.
243PH/11 In a ${run expansion, the variable $value (which contains the standard
244 output) is now also usable in the "else" string.
246PH/12 In a pipe transport, although a timeout while waiting for the pipe
247 process to complete was treated as a delivery failure, a timeout while
248 writing the message to the pipe was logged, but erroneously treated as a
249 successful delivery. Such timeouts include transport filter timeouts. For
250 consistency with the overall process timeout, these timeouts are now
251 treated as errors, giving rise to delivery failures by default. However,
252 there is now a new Boolean option for the pipe transport called
253 timeout_defer, which, if set TRUE, converts the failures into defers for
254 both kinds of timeout. A transport filter timeout is now identified in
255 the log output.
7766a4f0 257
f7b63901 258Version 4.50
b9e40c51 261The documentation is up-to-date for the 4.50 release.