X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/1a46a8c5c398c91f20c3f4def0ceb448ec8de96a..e5a9dba621b4301bfbe2bc05576ddc5ec752b1b5:/doc/doc-txt/NewStuff?ds=sidebyside diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff index 383c0f6f4..98c6fe258 100644 --- a/doc/doc-txt/NewStuff +++ b/doc/doc-txt/NewStuff @@ -1,4 +1,4 @@ -$Cambridge: exim/doc/doc-txt/NewStuff,v 1.28 2005/03/22 14:11:54 ph10 Exp $ +$Cambridge: exim/doc/doc-txt/NewStuff,v 1.40 2005/05/10 10:19:11 ph10 Exp $ New Features in Exim -------------------- @@ -9,6 +9,66 @@ updated when there is a relatively large batch of changes). The doc/ChangeLog file contains a listing of all changes, including bug fixes. +Exim version 4.52 +----------------- + +TF/01 Support for checking Client SMTP Authorization has been added. CSA is a + system which allows a site to advertise which machines are and are not + permitted to send email. This is done by placing special SRV records in + the DNS, which are looked up using the client's HELO domain. At this + time CSA is still an Internet-Draft. + + Client SMTP Authorization checks are performed by the ACL condition + verify=csa. This will fail if the client is not authorized. If there is + a DNS problem, or if no valid CSA SRV record is found, or if the client + is authorized, the condition succeeds. These three cases can be + distinguished using the expansion variable $csa_status, which can take + one of the values "fail", "defer", "unknown", or "ok". The condition + does not itself defer because that would be likely to cause problems + for legitimate email. + + The error messages produced by the CSA code include slightly more + detail. If $csa_status is "defer" this may be because of problems + looking up the CSA SRV record, or problems looking up the CSA target + address record. There are four reasons for $csa_status being "fail": + the client's host name is explicitly not authorized; the client's IP + address does not match any of the CSA target IP addresses; the client's + host name is authorized but it has no valid target IP addresses (e.g. + the target's addresses are IPv6 and the client is using IPv4); or the + client's host name has no CSA SRV record but a parent domain has + asserted that all subdomains must be explicitly authorized. + + The verify=csa condition can take an argument which is the domain to + use for the DNS query. The default is verify=csa/$sender_helo_name. + + This implementation includes an extension to CSA. If the query domain + is an address literal such as [192.0.2.95], or if it is a bare IP + address, Exim will search for CSA SRV records in the reverse DNS as if + the HELO domain was e.g. 95.2.0.192.in-addr.arpa. Therefore it is + meaningful to say, for example, verify=csa/$sender_host_address - in + fact, this is the check that Exim performs if the client does not say + HELO. This extension can be turned off by setting the main + configuration option dns_csa_use_reverse = false. + + If a CSA SRV record is not found for the domain itself, then a search + is performed through its parent domains for a record which might be + making assertions about subdomains. The maximum depth of this search is + limited using the main configuration option dns_csa_search_limit, which + takes the value 5 by default. Exim does not look for CSA SRV records in + a top level domain, so the default settings handle HELO domains as long + as seven (hostname.five.four.three.two.one.com) which encompasses the + vast majority of legitimate HELO domains. + + The dnsdb lookup also has support for CSA. Although dnsdb already + supports SRV lookups, this is not sufficient because of the extra + parent domain search behaviour of CSA, and (as with PTR lookups) + dnsdb also turns IP addresses into lookups in the reverse DNS space. + The result of ${lookup dnsdb {csa=$sender_helo_name} } has two + space-separated fields: an authorization code and a target host name. + The authorization code can be "Y" for yes, "N" for no, "X" for explicit + authorization required but absent, or "?" for unknown. + + Version 4.51 ------------ @@ -46,12 +106,20 @@ PH/02 A new expansion item for dynamically loading and calling a locally- 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.) - You load and call the function like this: + + 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 it so that it doesn't reload it in the same - Exim process (but of course Exim does start new processes frequently). + 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 @@ -79,6 +147,100 @@ PH/02 A new expansion item for dynamically loading and calling a locally- 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. + +PH/11 In a ${run expansion, the variable $value (which contains the standard + output) is now also usable in the "else" string. + +PH/12 In a pipe transport, although a timeout while waiting for the pipe + process to complete was treated as a delivery failure, a timeout while + writing the message to the pipe was logged, but erroneously treated as a + successful delivery. Such timeouts include transport filter timeouts. For + consistency with the overall process timeout, these timeouts are now + treated as errors, giving rise to delivery failures by default. However, + there is now a new Boolean option for the pipe transport called + timeout_defer, which, if set TRUE, converts the failures into defers for + both kinds of timeout. A transport filter timeout is now identified in + the log output. + Version 4.50 ------------