Commit | Line | Data |
---|---|---|
13b685f9 | 1 | $Cambridge: exim/doc/doc-txt/NewStuff,v 1.57 2005/08/01 13:20:28 ph10 Exp $ |
495ae4b0 PH |
2 | |
3 | New Features in Exim | |
4 | -------------------- | |
5 | ||
6 | This file contains descriptions of new features that have been added to Exim, | |
7 | but have not yet made it into the main manual (which is most conveniently | |
8 | updated when there is a relatively large batch of changes). The doc/ChangeLog | |
9 | file contains a listing of all changes, including bug fixes. | |
10 | ||
e3a311ba TK |
11 | Exim version 4.53 |
12 | ----------------- | |
13 | ||
14 | TK/01 Added the "success_on_redirect" address verification option. When an | |
15 | address generates new addresses during routing, Exim will abort | |
16 | verification with "success" when more than one address has been | |
17 | generated, but continue to verify a single new address. The latter | |
18 | does not happen when the new "success_on_redirect" option is set, like | |
19 | ||
20 | require verify = recipient/success_on_redirect/callout=10s | |
21 | ||
22 | In that case, verification will succeed when a router generates a new | |
23 | address. | |
24 | ||
13b685f9 PH |
25 | PH/01 Support for SQLite database lookups has been added. This is another |
26 | query-style lookup, but it is slightly different from the others because | |
27 | a file name is required in addition to the SQL query. This is because an | |
28 | SQLite database is a single file and there is no daemon as in other SQL | |
29 | databases. The interface to Exim requires the name of the file, as an | |
30 | absolute path, to be given at the start of the query. It is separated | |
31 | from the query by white space. This means that the path name cannot | |
32 | contain white space. Here is a lookup expansion example: | |
33 | ||
34 | ${lookup sqlite {/some/thing/sqlitedb \ | |
35 | select name from aliases where id='ph10';}} | |
36 | ||
37 | In a list, the syntax is similar. For example: | |
38 | ||
39 | domainlist relay_domains = sqlite;/some/thing/sqlitedb \ | |
40 | select * from relays where ip='$sender_host_address'; | |
41 | ||
42 | The only character affected by the ${quote_sqlite: operator is a single | |
43 | quote, which it doubles. | |
44 | ||
45 | Note that you must set LOOKUP_SQLITE=yes in Local/Makefile in order to | |
46 | obtain SQLite support, and you will also need to add -lsqlite3 to the | |
47 | EXTRALIBS setting. And of course, you have to install SQLite on your | |
48 | host first. | |
49 | ||
495ae4b0 | 50 | |
e5a9dba6 PH |
51 | Exim version 4.52 |
52 | ----------------- | |
53 | ||
54 | TF/01 Support for checking Client SMTP Authorization has been added. CSA is a | |
55 | system which allows a site to advertise which machines are and are not | |
56 | permitted to send email. This is done by placing special SRV records in | |
57 | the DNS, which are looked up using the client's HELO domain. At this | |
58 | time CSA is still an Internet-Draft. | |
59 | ||
60 | Client SMTP Authorization checks are performed by the ACL condition | |
61 | verify=csa. This will fail if the client is not authorized. If there is | |
62 | a DNS problem, or if no valid CSA SRV record is found, or if the client | |
63 | is authorized, the condition succeeds. These three cases can be | |
64 | distinguished using the expansion variable $csa_status, which can take | |
65 | one of the values "fail", "defer", "unknown", or "ok". The condition | |
66 | does not itself defer because that would be likely to cause problems | |
67 | for legitimate email. | |
68 | ||
69 | The error messages produced by the CSA code include slightly more | |
70 | detail. If $csa_status is "defer" this may be because of problems | |
71 | looking up the CSA SRV record, or problems looking up the CSA target | |
72 | address record. There are four reasons for $csa_status being "fail": | |
73 | the client's host name is explicitly not authorized; the client's IP | |
74 | address does not match any of the CSA target IP addresses; the client's | |
75 | host name is authorized but it has no valid target IP addresses (e.g. | |
76 | the target's addresses are IPv6 and the client is using IPv4); or the | |
77 | client's host name has no CSA SRV record but a parent domain has | |
78 | asserted that all subdomains must be explicitly authorized. | |
79 | ||
80 | The verify=csa condition can take an argument which is the domain to | |
81 | use for the DNS query. The default is verify=csa/$sender_helo_name. | |
82 | ||
83 | This implementation includes an extension to CSA. If the query domain | |
84 | is an address literal such as [192.0.2.95], or if it is a bare IP | |
85 | address, Exim will search for CSA SRV records in the reverse DNS as if | |
86 | the HELO domain was e.g. 95.2.0.192.in-addr.arpa. Therefore it is | |
87 | meaningful to say, for example, verify=csa/$sender_host_address - in | |
88 | fact, this is the check that Exim performs if the client does not say | |
89 | HELO. This extension can be turned off by setting the main | |
90 | configuration option dns_csa_use_reverse = false. | |
91 | ||
92 | If a CSA SRV record is not found for the domain itself, then a search | |
93 | is performed through its parent domains for a record which might be | |
94 | making assertions about subdomains. The maximum depth of this search is | |
95 | limited using the main configuration option dns_csa_search_limit, which | |
96 | takes the value 5 by default. Exim does not look for CSA SRV records in | |
97 | a top level domain, so the default settings handle HELO domains as long | |
98 | as seven (hostname.five.four.three.two.one.com) which encompasses the | |
99 | vast majority of legitimate HELO domains. | |
100 | ||
101 | The dnsdb lookup also has support for CSA. Although dnsdb already | |
102 | supports SRV lookups, this is not sufficient because of the extra | |
103 | parent domain search behaviour of CSA, and (as with PTR lookups) | |
104 | dnsdb also turns IP addresses into lookups in the reverse DNS space. | |
105 | The result of ${lookup dnsdb {csa=$sender_helo_name} } has two | |
106 | space-separated fields: an authorization code and a target host name. | |
107 | The authorization code can be "Y" for yes, "N" for no, "X" for explicit | |
108 | authorization required but absent, or "?" for unknown. | |
109 | ||
c1ac6996 PH |
110 | PH/01 The amount of output produced by the "make" process has been reduced, |
111 | because the compile lines are often rather long, making it all pretty | |
112 | unreadable. The new style is along the lines of the 2.6 Linux kernel: | |
113 | just a short line for each module that is being compiled or linked. | |
114 | However, it is still possible to get the full output, by calling "make" | |
115 | like this: | |
116 | ||
117 | FULLECHO='' make -e | |
118 | ||
119 | The value of FULLECHO defaults to "@", the flag character that suppresses | |
120 | command reflection in "make". When you ask for the full output, it is | |
121 | given in addition to the the short output. | |
122 | ||
4df1e33e | 123 | TF/02 There have been two changes concerned with submission mode: |
87ba3f5f | 124 | |
4df1e33e TF |
125 | Until now submission mode always left the return path alone, whereas |
126 | locally-submitted messages from untrusted users have the return path | |
127 | fixed to the user's email address. Submission mode now fixes the return | |
128 | path to the same address as is used to create the Sender: header. If | |
129 | /sender_retain is specified then both the Sender: header and the return | |
130 | path are left alone. | |
87ba3f5f | 131 | |
4df1e33e TF |
132 | Note that the changes caused by submission mode take effect after the |
133 | predata ACL. This means that any sender checks performed before the | |
134 | fix-ups will use the untrusted sender address specified by the user, not | |
135 | the trusted sender address specified by submission mode. Although this | |
136 | might be slightly unexpected, it does mean that you can configure ACL | |
137 | checks to spot that a user is trying to spoof another's address, for | |
138 | example. | |
87ba3f5f | 139 | |
4df1e33e TF |
140 | There is also a new /name= option for submission mode which allows you |
141 | to specify the user's full name to be included in the Sender: header. | |
142 | For example: | |
143 | ||
144 | accept authenticated = * | |
145 | control = submission/name=${lookup {$authenticated_id} \ | |
146 | lsearch {/etc/exim/namelist} } | |
147 | ||
148 | The namelist file contains entries like | |
149 | ||
150 | fanf: Tony Finch | |
151 | ||
152 | And the resulting Sender: header looks like | |
153 | ||
154 | Sender: Tony Finch <fanf@exim.org> | |
155 | ||
156 | TF/03 The control = fakereject ACL modifier now has a fakedefer counterpart, | |
29aba418 TF |
157 | which works in exactly the same way except it causes a fake SMTP 450 |
158 | response after the message data instead of a fake SMTP 550 response. | |
159 | You must take care when using fakedefer because it will cause messages | |
160 | to be duplicated when the sender retries. Therefore you should not use | |
161 | fakedefer if the message will be delivered normally. | |
162 | ||
870f6ba8 TF |
163 | TF/04 There is a new ratelimit ACL condition which can be used to measure |
164 | and control the rate at which clients can send email. This is more | |
165 | powerful than the existing smtp_ratelimit_* options, because those | |
166 | options only control the rate of commands in a single SMTP session, | |
167 | whereas the new ratelimit condition works across all connections | |
168 | (concurrent and sequential) to the same host. | |
169 | ||
170 | The syntax of the ratelimit condition is: | |
171 | ||
172 | ratelimit = <m> / <p> / <options> / <key> | |
173 | ||
3348576f TF |
174 | If the average client sending rate is less than m messages per time |
175 | period p then the condition is false, otherwise it is true. | |
870f6ba8 TF |
176 | |
177 | The parameter p is the smoothing time constant, in the form of an Exim | |
178 | time interval e.g. 8h for eight hours. A larger time constant means it | |
179 | takes Exim longer to forget a client's past behaviour. The parameter m is | |
180 | the maximum number of messages that a client can send in a fast burst. By | |
181 | increasing both m and p but keeping m/p constant, you can allow a client | |
182 | to send more messages in a burst without changing its overall sending | |
183 | rate limit. Conversely, if m and p are both small then messages must be | |
184 | sent at an even rate. | |
185 | ||
186 | The key is used to look up the data used to calcluate the client's | |
187 | average sending rate. This data is stored in a database maintained by | |
188 | Exim in its spool directory alongside the retry database etc. For | |
189 | example, you can limit the sending rate of each authenticated user, | |
190 | independent of the computer they are sending from, by setting the key | |
191 | to $authenticated_id. The default key is $sender_host_address. | |
dceb978c TF |
192 | Internally, Exim includes the smoothing constant p and the options in |
193 | the lookup key because they alter the meaning of the stored data. | |
194 | This is not true for the limit m, so you can alter the configured | |
195 | maximum rate and Exim will still remember clients' past behaviour, | |
196 | but if you alter the other ratelimit parameters Exim will effectively | |
197 | forget their past behaviour. | |
870f6ba8 TF |
198 | |
199 | Each ratelimit condition can have up to two options. The first option | |
200 | specifies what Exim measures the rate of, and the second specifies how | |
201 | Exim handles excessively fast clients. | |
202 | ||
203 | The per_mail option means that it measures the client's rate of sending | |
204 | messages. This is the default if none of the per_* options is specified. | |
205 | ||
206 | The per_conn option means that it measures the client's connection rate. | |
207 | ||
208 | The per_byte option limits the sender's email bandwidth. Note that it | |
209 | is best to use this option in the DATA ACL; if it is used in an earlier | |
210 | ACL it relies on the SIZE parameter on the MAIL command, which may be | |
211 | inaccurate or completely missing. You can follow the limit m in the | |
212 | configuration with K, M, or G to specify limits in kilobytes, | |
213 | megabytes, or gigabytes respectively. | |
214 | ||
215 | The per_cmd option means that Exim recomputes the rate every time the | |
216 | condition is processed, which can be used to limit the SMTP command rate. | |
217 | The alias per_rcpt is provided for use in the RCPT ACL instead of per_cmd | |
218 | to make it clear that the effect is to limit the rate at which recipients | |
219 | are accepted. Note that in this case the rate limiting engine will see a | |
220 | message with many recipients as a large high-speed burst. | |
221 | ||
222 | If a client's average rate is greater than the maximum, the rate | |
223 | limiting engine can react in two possible ways, depending on the | |
224 | presence of the strict or leaky options. This is independent of the | |
225 | other counter-measures (e.g. rejecting the message) that may be | |
226 | specified by the rest of the ACL. The default mode is leaky, which | |
227 | avoids a sender's over-aggressive retry rate preventing it from getting | |
228 | any email through. | |
229 | ||
230 | The strict option means that the client's recorded rate is always | |
231 | updated. The effect of this is that Exim measures the client's average | |
232 | rate of attempts to send email, which can be much higher than the | |
233 | maximum. If the client is over the limit it will be subjected to | |
234 | counter-measures until it slows down below the maximum rate. | |
235 | ||
236 | The leaky option means that the client's recorded rate is not updated | |
237 | if it is above the limit. The effect of this is that Exim measures the | |
238 | client's average rate of successfully sent email, which cannot be | |
239 | greater than the maximum. If the client is over the limit it will | |
240 | suffer some counter-measures, but it will still be able to send email | |
241 | at the configured maximum rate, whatever the rate of its attempts. | |
242 | ||
243 | As a side-effect, the ratelimit condition will set the expansion | |
244 | variables $sender_rate containing the client's computed rate, | |
245 | $sender_rate_limit containing the configured value of m, and | |
246 | $sender_rate_period containing the configured value of p. | |
247 | ||
248 | Exim's other ACL facilities are used to define what counter-measures | |
249 | are taken when the rate limit is exceeded. This might be anything from | |
250 | logging a warning (e.g. while measuring existing sending rates in order | |
251 | to define our policy), through time delays to slow down fast senders, | |
252 | up to rejecting the message. For example, | |
253 | ||
254 | # Log all senders' rates | |
255 | warn | |
256 | ratelimit = 0 / 1h / strict | |
257 | log_message = \ | |
258 | Sender rate $sender_rate > $sender_rate_limit / $sender_rate_period | |
259 | ||
260 | # Slow down fast senders | |
261 | warn | |
262 | ratelimit = 100 / 1h / per_rcpt / strict | |
263 | delay = ${eval: 10 * ($sender_rate - $sender_rate_limit) } | |
264 | ||
265 | # Keep authenticated users under control | |
266 | deny | |
267 | ratelimit = 100 / 1d / strict / $authenticated_id | |
268 | ||
269 | # System-wide rate limit | |
270 | defer | |
271 | message = Sorry, too busy. Try again later. | |
272 | ratelimit = 10 / 1s / $primary_hostname | |
273 | ||
274 | # Restrict incoming rate from each host, with a default rate limit | |
275 | # set using a macro and special cases looked up in a table. | |
276 | defer | |
277 | message = Sender rate $sender_rate exceeds \ | |
278 | $sender_rate_limit messages per $sender_rate_period | |
279 | ratelimit = ${lookup {$sender_host_address} \ | |
280 | cdb {DB/ratelimits.cdb} \ | |
281 | {$value} {RATELIMIT} } | |
282 | ||
894a6bd8 TF |
283 | Warning: if you have a busy server with a lot of ratelimit tests, |
284 | especially with the per_rcpt option, you may suffer from a performance | |
285 | bottleneck caused by locking on the ratelimit hints database. Apart from | |
286 | making your ACLs less complicated, you can reduce the problem by using a | |
287 | RAM disk for Exim's hints directory, /var/spool/exim/db/. However this | |
288 | means that Exim will lose its hints data after a reboot (including retry | |
289 | hints, the callout cache, and ratelimit data). | |
290 | ||
7d50add3 TK |
291 | TK/01 Added an 'spf' lookup type that will return an SPF result for a given |
292 | email address (the key) and an IP address (the database): | |
293 | ||
294 | ${lookup {tom@duncanthrax.net} spf{217.115.139.137}} | |
295 | ||
296 | The lookup will return the same result strings as they can appear in | |
297 | $spf_result (pass,fail,softfail,neutral,none,err_perm,err_temp). The | |
298 | lookup is armored in EXPERIMENTAL_SPF. Currently, only IPv4 addresses | |
299 | are supported. | |
300 | ||
301 | Patch submitted by Chris Webb <chris@arachsys.com>. | |
302 | ||
2a4be8f9 PH |
303 | PH/02 There's a new verify callout option, "fullpostmaster", which first acts |
304 | as "postmaster" and checks the recipient <postmaster@domain>. If that | |
305 | fails, it tries just <postmaster>, without a domain, in accordance with | |
306 | the specification in RFC 2821. | |
307 | ||
ef213c3b PH |
308 | PH/03 The action of the auto_thaw option has been changed. It no longer applies |
309 | to frozen bounce messages. | |
310 | ||
0cd68797 TK |
311 | TK/02 There are two new expansion items to help with the implementation of |
312 | the BATV "prvs" scheme in an Exim configuration: | |
313 | ||
314 | ||
315 | ${prvs {<ADDRESS>}{<KEY>}{[KEYNUM]}} | |
316 | ||
317 | The "prvs" expansion item takes three arguments: A qualified RFC2821 | |
318 | email address, a key and an (optional) key number. All arguments are | |
319 | expanded before being used, so it is easily possible to lookup a key | |
320 | and key number using the address as the lookup key. The key number is | |
321 | optional and defaults to "0". The item will expand to a "prvs"-signed | |
322 | email address, to be typically used with the "return_path" option on | |
323 | a smtp transport. The decision if BATV should be used with a given | |
324 | sender/recipient pair should be done on router level, to avoid having | |
325 | to set "max_rcpt = 1" on the transport. | |
326 | ||
327 | ||
328 | ${prvscheck {<ADDRESS>}{<SECRET>}{<RETURN_STRING>}} | |
329 | ||
330 | The "prvscheck" expansion item takes three arguments. Argument 1 is | |
331 | expanded first. When the expansion does not yield a SYNTACTICALLY | |
332 | valid "prvs"-scheme address, the whole "prvscheck" item expands to | |
333 | the empty string. If <ADDRESS> is a "prvs"-encoded address after | |
334 | expansion, two expansion variables are set up: | |
335 | ||
336 | $prvscheck_address Contains the "prvs"-decoded version of | |
337 | the address from argument 1. | |
338 | ||
339 | $prvscheck_keynum Contains the key number extracted from | |
340 | the "prvs"-address in argument 1. | |
341 | ||
342 | These two variables can be used in the expansion code of argument 2 | |
343 | to retrieve the <SECRET>. The VALIDITY of the "prvs"-signed address | |
344 | is then checked. The result is stored in yet another expansion | |
345 | variable: | |
346 | ||
347 | $prvscheck_result Contains the result of a "prvscheck" | |
348 | expansion: Unset (the empty string) for | |
349 | failure, "1" for success. | |
350 | ||
351 | The "prvscheck" expansion expands to the empty string if <ADDRESS> | |
352 | is not a SYNTACTICALLY valid "prvs"-scheme address. Otherwise, | |
353 | argument 3 defines what "prvscheck" expands to: If argument 3 | |
354 | is the empty string, "prvscheck" expands to the decoded version | |
355 | of the address (no matter if it is CRYPTOGRAPHICALLY valid or not). | |
356 | If argument 3 expands to a non-empty string, "prvscheck" expands | |
357 | to that string. | |
358 | ||
359 | ||
360 | Usage example | |
361 | ------------- | |
362 | ||
363 | Macro: | |
364 | ||
365 | PRVSCHECK_SQL = ${lookup mysql{SELECT secret FROM batv_prvs WHERE \ | |
366 | sender='${quote_mysql:$prvscheck_address}'}{$value}} | |
367 | ||
368 | RCPT ACL: | |
369 | ||
370 | # Bounces: drop unsigned addresses for BATV senders | |
371 | deny message = This address does not send an unsigned reverse path. | |
372 | senders = : | |
373 | recipients = +batv_recipients | |
374 | ||
375 | # Bounces: In case of prvs-signed address, check signature. | |
376 | deny message = Invalid reverse path signature. | |
377 | senders = : | |
378 | condition = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{1}} | |
379 | !condition = $prvscheck_result | |
380 | ||
381 | Top-Level Router: | |
382 | ||
383 | batv_redirect: | |
384 | driver = redirect | |
385 | data = ${prvscheck {$local_part@$domain}{PRVSCHECK_SQL}{}} | |
386 | ||
387 | Transport (referenced by router that makes decision if | |
388 | BATV is applicable): | |
389 | ||
390 | external_smtp_batv: | |
391 | driver = smtp | |
392 | return_path = ${prvs {$return_path} \ | |
393 | {${lookup mysql{SELECT \ | |
394 | secret FROM batv_prvs WHERE \ | |
395 | sender='${quote_mysql:$sender_address}'} \ | |
396 | {$value}fail}}} | |
397 | ||
4aee0225 PH |
398 | PH/04 There are two new options that control the retrying done by the daemon |
399 | at startup when it cannot immediately bind a socket (typically because | |
400 | the socket is already in use). The default values reproduce what were | |
401 | built-in constants previously: daemon_startup_retries defines the number | |
402 | of retries after the first failure (default 9); daemon_startup_sleep | |
403 | defines the length of time to wait between retries (default 30s). | |
0cd68797 | 404 | |
32d668a5 PH |
405 | PH/05 There is now a new ${if condition called "match_ip". It is similar to |
406 | match_domain, etc. It must be followed by two argument strings. The first | |
407 | (after expansion) must be an IP address or an empty string. The second | |
408 | (after expansion) is a restricted host list that can match only an IP | |
409 | address, not a host name. For example: | |
410 | ||
411 | ${if match_ip{$sender_host_address}{1.2.3.4:5.6.7.8}{...}{...}} | |
412 | ||
413 | The specific types of host list item that are permitted in the list are | |
414 | shown below. Consult the manual section on host lists for further | |
415 | details. | |
416 | ||
417 | . An IP address, optionally with a CIDR mask. | |
418 | ||
419 | . A single asterisk matches any IP address. | |
420 | ||
421 | . An empty item matches only if the IP address is empty. This could be | |
422 | useful for testing for a locally submitted message or one from specific | |
423 | hosts in a single test such as | |
424 | ||
425 | ${if match_ip{$sender_host_address}{:4.3.2.1:...}{...}{...}} | |
426 | ||
427 | where the first item in the list is the empty string. | |
428 | ||
429 | . The item @[] matches any of the local host's interface addresses. | |
430 | ||
431 | . Lookups are assumed to be "net-" style lookups, even if "net-" is not | |
432 | specified. Thus, the following are equivalent: | |
433 | ||
434 | ${if match_ip{$sender_host_address}{lsearch;/some/file}... | |
435 | ${if match_ip{$sender_host_address}{net-lsearch;/some/file}... | |
436 | ||
437 | You do need to specify the "net-" prefix if you want to specify a | |
438 | specific address mask, for example, by using "net24-". | |
439 | ||
056eb8b5 PH |
440 | PH/06 The "+all" debug selector used to set the flags for all possible output; |
441 | it is something that people tend to use semi-automatically when | |
442 | generating debug output for me or for the list. However, by including | |
443 | "+memory", an awful lot of output that is very rarely of interest was | |
444 | generated. I have changed this so that "+all" no longer includes | |
445 | "+memory". However, "-all" still turns everything off. | |
446 | ||
e5a9dba6 | 447 | |
b5aea5e1 PH |
448 | Version 4.51 |
449 | ------------ | |
450 | ||
1a46a8c5 PH |
451 | PH/01 The format in which GnuTLS parameters are written to the gnutls-param |
452 | file in the spool directory has been changed. This change has been made | |
453 | to alleviate problems that some people had with the generation of the | |
454 | parameters by Exim when /dev/random was exhausted. In this situation, | |
455 | Exim would hang until /dev/random acquired some more entropy. | |
456 | ||
457 | The new code exports and imports the DH and RSA parameters in PEM | |
458 | format. This means that the parameters can be generated externally using | |
459 | the certtool command that is part of GnuTLS. | |
460 | ||
461 | To replace the parameters with new ones, instead of deleting the file | |
462 | and letting Exim re-create it, you can generate new parameters using | |
463 | certtool and, when this has been done, replace Exim's cache file by | |
464 | renaming. The relevant commands are something like this: | |
465 | ||
466 | # rm -f new.params | |
467 | # touch new.params | |
468 | # chown exim:exim new.params | |
469 | # chmod 0400 new.params | |
470 | # certtool --generate-privkey --bits 512 >new.params | |
471 | # echo "" >>new.params | |
472 | # certtool --generate-dh-params --bits 1024 >> new.params | |
473 | # mv new.params params | |
474 | ||
475 | If Exim never has to generate the parameters itself, the possibility of | |
476 | stalling is removed. | |
477 | ||
478 | PH/02 A new expansion item for dynamically loading and calling a locally- | |
479 | written C function is now provided, if Exim is compiled with | |
480 | ||
481 | EXPAND_DLFUNC=yes | |
482 | ||
483 | set in Local/Makefile. The facility is not included by default (a | |
484 | suitable error is given if you try to use it when it is not there.) | |
4754440d PH |
485 | |
486 | If you enable EXPAND_DLFUNC, you should also be aware of the new redirect | |
487 | router option forbid_filter_dlfunc. If you have unprivileged users on | |
488 | your system who are permitted to create filter files, you might want to | |
489 | set forbid_filter_dlfunc=true in the appropriate router, to stop them | |
490 | using ${dlfunc to run code within Exim. | |
491 | ||
492 | You load and call an external function like this: | |
1a46a8c5 PH |
493 | |
494 | ${dlfunc{/some/file}{function}{arg1}{arg2}...} | |
495 | ||
4754440d PH |
496 | Once loaded, Exim remembers the dynamically loaded object so that it |
497 | doesn't reload the same object file in the same Exim process (but of | |
498 | course Exim does start new processes frequently). | |
1a46a8c5 PH |
499 | |
500 | There may be from zero to eight arguments to the function. When compiling | |
501 | a local function that is to be called in this way, local_scan.h should be | |
502 | included. The Exim variables and functions that are defined by that API | |
503 | are also available for dynamically loaded functions. The function itself | |
504 | must have the following type: | |
505 | ||
506 | int dlfunction(uschar **yield, int argc, uschar *argv[]) | |
507 | ||
508 | Where "uschar" is a typedef for "unsigned char" in local_scan.h. The | |
509 | function should return one of the following values: | |
510 | ||
511 | OK Success. The string that is placed in "yield" is put into | |
512 | the expanded string that is being built. | |
513 | ||
514 | FAIL A non-forced expansion failure occurs, with the error | |
515 | message taken from "yield", if it is set. | |
516 | ||
517 | FAIL_FORCED A forced expansion failure occurs, with the error message | |
518 | taken from "yield" if it is set. | |
519 | ||
520 | ERROR Same as FAIL, except that a panic log entry is written. | |
521 | ||
522 | When compiling a function that is to be used in this way with gcc, | |
523 | you need to add -shared to the gcc command. Also, in the Exim build-time | |
524 | configuration, you must add -export-dynamic to EXTRALIBS. | |
b5aea5e1 | 525 | |
7dbf77c9 PH |
526 | TF/01 $received_time is a new expansion variable containing the time and date |
527 | as a number of seconds since the start of the Unix epoch when the | |
528 | current message was received. | |
b5aea5e1 | 529 | |
7766a4f0 PH |
530 | PH/03 There is a new value for RADIUS_LIB_TYPE that can be set in |
531 | Local/Makefile. It is RADIUSCLIENTNEW, and it requests that the new API, | |
532 | in use from radiusclient 0.4.0 onwards, be used. It does not appear to be | |
533 | possible to detect the different versions automatically. | |
534 | ||
54cdb463 PH |
535 | PH/04 There is a new option called acl_not_smtp_mime that allows you to scan |
536 | MIME parts in non-SMTP messages. It operates in exactly the same way as | |
537 | acl_smtp_mime | |
538 | ||
cf00dad6 PH |
539 | PH/05 It is now possible to redefine a macro within the configuration file. |
540 | The macro must have been previously defined within the configuration (or | |
541 | an included file). A definition on the command line using the -D option | |
542 | causes all definitions and redefinitions within the file to be ignored. | |
543 | In other words, -D overrides any values that are set in the file. | |
544 | Redefinition is specified by using '==' instead of '='. For example: | |
545 | ||
546 | MAC1 = initial value | |
547 | ... | |
548 | MAC1 == updated value | |
549 | ||
550 | Redefinition does not alter the order in which the macros are applied to | |
551 | the subsequent lines of the configuration file. It is still the same | |
552 | order in which the macros were originally defined. All that changes is | |
553 | the macro's value. Redefinition makes it possible to accumulate values. | |
554 | For example: | |
555 | ||
556 | MAC1 = initial value | |
557 | ... | |
558 | MAC1 == MAC1 and something added | |
559 | ||
560 | This can be helpful in situations where the configuration file is built | |
561 | from a number of other files. | |
562 | ||
563 | PH/06 Macros may now be defined or redefined between router, transport, | |
564 | authenticator, or ACL definitions, as well as in the main part of the | |
565 | configuration. They may not, however, be changed within an individual | |
566 | driver or ACL, or in the local_scan, retry, or rewrite sections of the | |
567 | configuration. | |
568 | ||
475fe28a PH |
569 | PH/07 $acl_verify_message is now set immediately after the failure of a |
570 | verification in an ACL, and so is available in subsequent modifiers. In | |
571 | particular, the message can be preserved by coding like this: | |
572 | ||
573 | warn !verify = sender | |
574 | set acl_m0 = $acl_verify_message | |
575 | ||
576 | Previously, $acl_verify_message was set only while expanding "message" | |
577 | and "log_message" when a very denied access. | |
578 | ||
e4a89c47 PH |
579 | PH/08 The redirect router has two new options, sieve_useraddress and |
580 | sieve_subaddress. These are passed to a Sieve filter to specify the :user | |
581 | and :subaddress parts of an address. Both options are unset by default. | |
582 | However, when a Sieve filter is run, if sieve_useraddress is unset, the | |
583 | entire original local part (including any prefix or suffix) is used for | |
584 | :user. An unset subaddress is treated as an empty subaddress. | |
475fe28a | 585 | |
be22d70e PH |
586 | PH/09 Quota values can be followed by G as well as K and M. |
587 | ||
2e0c1448 PH |
588 | PH/10 $message_linecount is a new variable that contains the total number of |
589 | lines in the header and body of the message. Compare $body_linecount, | |
590 | which is the count for the body only. During the DATA and | |
591 | content-scanning ACLs, $message_linecount contains the number of lines | |
592 | received. Before delivery happens (that is, before filters, routers, and | |
593 | transports run) the count is increased to include the Received: header | |
594 | line that Exim standardly adds, and also any other header lines that are | |
595 | added by ACLs. The blank line that separates the message header from the | |
596 | body is not counted. Here is an example of the use of this variable in a | |
597 | DATA ACL: | |
598 | ||
599 | deny message = Too many lines in message header | |
600 | condition = \ | |
601 | ${if <{250}{${eval: $message_linecount - $body_linecount}}} | |
602 | ||
603 | In the MAIL and RCPT ACLs, the value is zero because at that stage the | |
604 | message has not yet been received. | |
605 | ||
d20976dc PH |
606 | PH/11 In a ${run expansion, the variable $value (which contains the standard |
607 | output) is now also usable in the "else" string. | |
608 | ||
2e2a30b4 PH |
609 | PH/12 In a pipe transport, although a timeout while waiting for the pipe |
610 | process to complete was treated as a delivery failure, a timeout while | |
611 | writing the message to the pipe was logged, but erroneously treated as a | |
612 | successful delivery. Such timeouts include transport filter timeouts. For | |
613 | consistency with the overall process timeout, these timeouts are now | |
614 | treated as errors, giving rise to delivery failures by default. However, | |
615 | there is now a new Boolean option for the pipe transport called | |
616 | timeout_defer, which, if set TRUE, converts the failures into defers for | |
617 | both kinds of timeout. A transport filter timeout is now identified in | |
618 | the log output. | |
619 | ||
7766a4f0 | 620 | |
f7b63901 | 621 | Version 4.50 |
35edf2ff PH |
622 | ------------ |
623 | ||
b9e40c51 | 624 | The documentation is up-to-date for the 4.50 release. |
495ae4b0 PH |
625 | |
626 | **** |