Typo in doc source.

[users/jgh/exim.git] / doc / doc-docbook / spec.xfpt

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 3e21c0291a9b6dc6d294457108b2564a6c33a617..d2653eaf46d0016ba943c2d82ae408fae479c951 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -41,16 +41,19 @@
 .book
 
 . /////////////////////////////////////////////////////////////////////////////
 .book
 
 . /////////////////////////////////////////////////////////////////////////////

-. These definitions set some parameters and save some typing. Remember that
-. the <bookinfo> element must also be updated for each new edition.
+. These definitions set some parameters and save some typing.
+. Update the Copyright year (only) when changing content.

 . /////////////////////////////////////////////////////////////////////////////
 
 .set previousversion "4.80"
 . /////////////////////////////////////////////////////////////////////////////
 
 .set previousversion "4.80"

-.set version "4.80"
+.include ./local_params

 
 .set ACL "access control lists (ACLs)"
 .set I   "&nbsp;&nbsp;&nbsp;&nbsp;"
 
 
 .set ACL "access control lists (ACLs)"
 .set I   "&nbsp;&nbsp;&nbsp;&nbsp;"
 

+.macro copyyear
+2012
+.endmacro

 
 . /////////////////////////////////////////////////////////////////////////////
 . Additional xfpt markup used by this document, over and above the default
 
 . /////////////////////////////////////////////////////////////////////////////
 . Additional xfpt markup used by this document, over and above the default


@@ -170,15 +173,23 @@
 <bookinfo>
 <title>Specification of the Exim Mail Transfer Agent</title>
 <titleabbrev>The Exim MTA</titleabbrev>
 <bookinfo>
 <title>Specification of the Exim Mail Transfer Agent</title>
 <titleabbrev>The Exim MTA</titleabbrev>

-<date>17 May 2012</date>
+<date>
+.fulldate
+</date>

 <author><firstname>Exim</firstname><surname>Maintainers</surname></author>
 <authorinitials>EM</authorinitials>
 <revhistory><revision>
 <author><firstname>Exim</firstname><surname>Maintainers</surname></author>
 <authorinitials>EM</authorinitials>
 <revhistory><revision>

-  <revnumber>4.80</revnumber>
-  <date>17 May 2012</date>
+  <revnumber>
+.version
+  </revnumber>
+  <date>
+.fulldate
+  </date>

   <authorinitials>EM</authorinitials>
 </revision></revhistory>
   <authorinitials>EM</authorinitials>
 </revision></revhistory>

-<copyright><year>2012</year><holder>University of Cambridge</holder></copyright>
+<copyright><year>
+.copyyear
+           </year><holder>University of Cambridge</holder></copyright>

 </bookinfo>
 .literal off
 
 </bookinfo>
 .literal off
 


@@ -367,7 +378,7 @@ contributors.
 
 .new
 .cindex "documentation"
 
 .new
 .cindex "documentation"

-This edition of the Exim specification applies to version &version; of Exim.
+This edition of the Exim specification applies to version &version() of Exim.

 Substantive changes from the &previousversion; edition are marked in some
 renditions of the document; this paragraph is so marked if the rendition is
 capable of showing a change indicator.
 Substantive changes from the &previousversion; edition are marked in some
 renditions of the document; this paragraph is so marked if the rendition is
 capable of showing a change indicator.


@@ -735,6 +746,7 @@ the Exim documentation, &"spool"& is always used in the first sense.
 .cindex "incorporated code"
 .cindex "regular expressions" "library"
 .cindex "PCRE"
 .cindex "incorporated code"
 .cindex "regular expressions" "library"
 .cindex "PCRE"

+.cindex "OpenDMARC"

 A number of pieces of external code are included in the Exim distribution.
 
 .ilist
 A number of pieces of external code are included in the Exim distribution.
 
 .ilist


@@ -859,6 +871,14 @@ ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 SOFTWARE.
 .endblockquote
 
 SOFTWARE.
 .endblockquote
 

+.next
+.cindex "opendmarc" "acknowledgment"
+The DMARC implementation uses the OpenDMARC library which is Copyrighted by
+The Trusted Domain Project. Portions of Exim source which use OpenDMARC
+derived code are indicated in the respective source files. The full OpenDMARC
+license is provided in the LICENSE.opendmarc file contained in the distributed
+source code.
+

 .next
 Many people have contributed code fragments, some large, some small, that were
 not covered by any specific licence requirements. It is assumed that the
 .next
 Many people have contributed code fragments, some large, some small, that were
 not covered by any specific licence requirements. It is assumed that the


@@ -1618,7 +1638,7 @@ for only a short time (see &%timeout_frozen_after%& and
 .section "Unpacking" "SECID23"
 Exim is distributed as a gzipped or bzipped tar file which, when unpacked,
 creates a directory with the name of the current release (for example,
 .section "Unpacking" "SECID23"
 Exim is distributed as a gzipped or bzipped tar file which, when unpacked,
 creates a directory with the name of the current release (for example,

-&_exim-&version;_&) into which the following files are placed:
+&_exim-&version()_&) into which the following files are placed:

 
 .table2 140pt
 .irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments"
 
 .table2 140pt
 .irow &_ACKNOWLEDGMENTS_& "contains some acknowledgments"


@@ -2314,7 +2334,7 @@ INFO_DIRECTORY, as described in section &<<SECTinsinfdoc>>& below.
 For the utility programs, old versions are renamed by adding the suffix &_.O_&
 to their names. The Exim binary itself, however, is handled differently. It is
 installed under a name that includes the version number and the compile number,
 For the utility programs, old versions are renamed by adding the suffix &_.O_&
 to their names. The Exim binary itself, however, is handled differently. It is
 installed under a name that includes the version number and the compile number,

-for example &_exim-&version;-1_&. The script then arranges for a symbolic link
+for example &_exim-&version()-1_&. The script then arranges for a symbolic link

 called &_exim_& to point to the binary. If you are updating a previous version
 of Exim, the script takes care to ensure that the name &_exim_& is never absent
 from the directory (as seen by other processes).
 called &_exim_& to point to the binary. If you are updating a previous version
 of Exim, the script takes care to ensure that the name &_exim_& is never absent
 from the directory (as seen by other processes).


@@ -4324,7 +4344,7 @@ For compatibility with Sendmail, this option is equivalent to
 It sets the incoming protocol and host name (for trusted callers). The
 host name and its colon can be omitted when only the protocol is to be set.
 Note the Exim already has two private options, &%-pd%& and &%-ps%&, that refer
 It sets the incoming protocol and host name (for trusted callers). The
 host name and its colon can be omitted when only the protocol is to be set.
 Note the Exim already has two private options, &%-pd%& and &%-ps%&, that refer

-to embedded Perl. It is therefore impossible to set a protocol value of &`p`&
+to embedded Perl. It is therefore impossible to set a protocol value of &`d`&

 or &`s`& using this option (but that does not seem a real limitation).
 
 .vitem &%-q%&
 or &`s`& using this option (but that does not seem a real limitation).
 
 .vitem &%-q%&


@@ -11739,6 +11759,12 @@ envelope sender.
 .vindex "&$return_size_limit$&"
 This is an obsolete name for &$bounce_return_size_limit$&.
 
 .vindex "&$return_size_limit$&"
 This is an obsolete name for &$bounce_return_size_limit$&.
 

+.vitem &$router_name$&
+.cindex "router" "name"
+.cindex "name" "of router"
+.vindex "&$router_name$&"
+During the running of a router this variable contains its name.
+

 .vitem &$runrc$&
 .cindex "return code" "from &%run%& expansion"
 .vindex "&$runrc$&"
 .vitem &$runrc$&
 .cindex "return code" "from &%run%& expansion"
 .vindex "&$runrc$&"


@@ -12193,6 +12219,12 @@ This variable contains the numerical value of the local timezone, for example:
 This variable contains the UTC date and time in &"Zulu"& format, as specified
 by ISO 8601, for example: 20030221154023Z.
 
 This variable contains the UTC date and time in &"Zulu"& format, as specified
 by ISO 8601, for example: 20030221154023Z.
 

+.vitem &$transport_name$&
+.cindex "transport" "name"
+.cindex "name" "of transport"
+.vindex "&$transport_name$&"
+During the running of a transport, this variable contains its name.
+

 .vitem &$value$&
 .vindex "&$value$&"
 This variable contains the result of an expansion lookup, extraction operation,
 .vitem &$value$&
 .vindex "&$value$&"
 This variable contains the result of an expansion lookup, extraction operation,


@@ -16043,6 +16075,9 @@ use OpenSSL with a directory.
 
 See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
 
 
 See &<<SECTtlssni>>& for discussion of when this option might be re-expanded.
 

+A forced expansion failure or setting to an empty string is equivalent to
+being unset.
+

 
 .option tls_verify_hosts main "host list&!!" unset
 .cindex "TLS" "client certificate verification"
 
 .option tls_verify_hosts main "host list&!!" unset
 .cindex "TLS" "client certificate verification"


@@ -16409,7 +16444,8 @@ be specified using &%condition%&.
 .option debug_print routers string&!! unset
 .cindex "testing" "variables in drivers"
 If this option is set and debugging is enabled (see the &%-d%& command line
 .option debug_print routers string&!! unset
 .cindex "testing" "variables in drivers"
 If this option is set and debugging is enabled (see the &%-d%& command line

-option), the string is expanded and included in the debugging output.
+option) or in address-testing mode (see the &%-bt%& command line option),
+the string is expanded and included in the debugging output.

 If expansion of the string fails, the error message is written to the debugging
 output, and Exim carries on processing.
 This option is provided to help with checking out the values of variables and
 If expansion of the string fails, the error message is written to the debugging
 output, and Exim carries on processing.
 This option is provided to help with checking out the values of variables and


@@ -16418,6 +16454,7 @@ option appears not to be working, &%debug_print%& can be used to output the
 variables it references. The output happens after checks for &%domains%&,
 &%local_parts%&, and &%check_local_user%& but before any other preconditions
 are tested. A newline is added to the text if it does not end with one.
 variables it references. The output happens after checks for &%domains%&,
 &%local_parts%&, and &%check_local_user%& but before any other preconditions
 are tested. A newline is added to the text if it does not end with one.

+The variable &$router_name$& contains the name of the router.

 
 
 
 
 
 


@@ -19578,6 +19615,8 @@ so on when debugging driver configurations. For example, if a &%headers_add%&
 option is not working properly, &%debug_print%& could be used to output the
 variables it references. A newline is added to the text if it does not end with
 one.
 option is not working properly, &%debug_print%& could be used to output the
 variables it references. A newline is added to the text if it does not end with
 one.

+The variables &$transport_name$& and &$router_name$& contain the name of the
+transport and the router that called it.

 
 
 .option delivery_date_add transports boolean false
 
 
 .option delivery_date_add transports boolean false


@@ -21571,10 +21610,10 @@ that are routed to the transport.
 .vindex "&$address_pipe$&"
 A router redirects an address directly to a pipe command (for example, from an
 alias or forward file). In this case, &$address_pipe$& contains the text of the
 .vindex "&$address_pipe$&"
 A router redirects an address directly to a pipe command (for example, from an
 alias or forward file). In this case, &$address_pipe$& contains the text of the

-pipe command, and the &%command%& option on the transport is ignored. If only
-one address is being transported (&%batch_max%& is not greater than one, or
-only one address was redirected to this pipe command), &$local_part$& contains
-the local part that was redirected.
+pipe command, and the &%command%& option on the transport is ignored unless
+&%force_command%& is set. If only one address is being transported
+(&%batch_max%& is not greater than one, or only one address was redirected to
+this pipe command), &$local_part$& contains the local part that was redirected.

 .endlist
 
 
 .endlist
 
 


@@ -21682,6 +21721,15 @@ inserted in the argument list at that point &'as a separate argument'&. This
 avoids any problems with spaces or shell metacharacters, and is of use when a
 &(pipe)& transport is handling groups of addresses in a batch.
 
 avoids any problems with spaces or shell metacharacters, and is of use when a
 &(pipe)& transport is handling groups of addresses in a batch.
 

+If &%force_command%& is enabled on the transport, Special handling takes place
+for an argument that consists of precisely the text &`$address_pipe`&.  It
+is handled similarly to &$pipe_addresses$& above.  It is expanded and each
+argument is inserted in the argument list at that point
+&'as a separate argument'&.  The &`$address_pipe`& item does not need to be
+the only item in the argument; in fact, if it were then &%force_command%&
+should behave as a no-op.  Rather, it should be used to adjust the command
+run while preserving the argument vector separation.
+

 After splitting up into arguments and expansion, the resulting command is run
 in a subprocess directly from the transport, &'not'& under a shell. The
 message that is being delivered is supplied on the standard input, and the
 After splitting up into arguments and expansion, the resulting command is run
 in a subprocess directly from the transport, &'not'& under a shell. The
 message that is being delivered is supplied on the standard input, and the


@@ -21834,6 +21882,23 @@ a bounce message is sent. If &%freeze_signal%& is set, the message will be
 frozen in Exim's queue instead.
 
 
 frozen in Exim's queue instead.
 
 

+.option force_command pipe boolean false
+.cindex "force command"
+.cindex "&(pipe)& transport", "force command"
+Normally when a router redirects an address directly to a pipe command
+the &%command%& option on the transport is ignored.  If &%force_command%&
+is set, the &%command%& option will used. This is especially
+useful for forcing a wrapper or additional argument to be added to the
+command. For example:
+.code
+command = /usr/bin/remote_exec myhost -- $address_pipe
+force_command
+.endd
+
+Note that &$address_pipe$& is handled specially in &%command%& when
+&%force_command%& is set, expanding out to the original argument vector as
+separate items, similarly to a Unix shell &`"$@"`& construct.
+

 .option ignore_status pipe boolean false
 If this option is true, the status returned by the subprocess that is set up to
 run the command is ignored, and Exim behaves as if zero had been returned.
 .option ignore_status pipe boolean false
 If this option is true, the status returned by the subprocess that is set up to
 run the command is ignored, and Exim behaves as if zero had been returned.


@@ -33649,9 +33714,9 @@ intermediate address(es) exist between the original and the final address, the
 last of these is given in parentheses after the final address. The R and T
 fields record the router and transport that were used to process the address.
 
 last of these is given in parentheses after the final address. The R and T
 fields record the router and transport that were used to process the address.
 

-If SMTP AUTH was used for the deliver there is an additional item A=
+If SMTP AUTH was used for the delivery there is an additional item A=

 followed by the name of the authenticator that was used.
 followed by the name of the authenticator that was used.

-If an authenticated identification was set up by the authenticator’s client_set_id
+If an authenticated identification was set up by the authenticator's &%client_set_id%&

 option, this is logged too, separated by a colon from the authenticator name.
 
 If a shadow transport was run after a successful local delivery, the log line
 option, this is logged too, separated by a colon from the authenticator name.
 
 If a shadow transport was run after a successful local delivery, the log line


@@ -33767,7 +33832,7 @@ at the end of its processing.
 A summary of the field identifiers that are used in log lines is shown in
 the following table:
 .display
 A summary of the field identifiers that are used in log lines is shown in
 the following table:
 .display

-&`A   `&        authenticator name (and optional id)
+&`A   `&        authenticator name (and optional id and sender)

 &`C   `&        SMTP confirmation on delivery
 &`    `&        command list for &"no mail in SMTP session"&
 &`CV  `&        certificate verification status
 &`C   `&        SMTP confirmation on delivery
 &`    `&        command list for &"no mail in SMTP session"&
 &`CV  `&        certificate verification status


@@ -33884,6 +33949,7 @@ selection marked by asterisks:
 &`*smtp_confirmation          `&  SMTP confirmation on => lines
 &` smtp_connection            `&  SMTP connections
 &` smtp_incomplete_transaction`&  incomplete SMTP transactions
 &`*smtp_confirmation          `&  SMTP confirmation on => lines
 &` smtp_connection            `&  SMTP connections
 &` smtp_incomplete_transaction`&  incomplete SMTP transactions

+&` smtp_mailauth              `&  AUTH argument to MAIL commands

 &` smtp_no_mail               `&  session with no MAIL commands
 &` smtp_protocol_error        `&  SMTP protocol errors
 &` smtp_syntax_error          `&  SMTP syntax errors
 &` smtp_no_mail               `&  session with no MAIL commands
 &` smtp_protocol_error        `&  SMTP protocol errors
 &` smtp_syntax_error          `&  SMTP syntax errors


@@ -34152,6 +34218,11 @@ the last 20 are listed, preceded by &"..."&. However, with the default
 setting of 10 for &%smtp_accep_max_nonmail%&, the connection will in any case
 have been aborted before 20 non-mail commands are processed.
 .next
 setting of 10 for &%smtp_accep_max_nonmail%&, the connection will in any case
 have been aborted before 20 non-mail commands are processed.
 .next

+&%smtp_mailauth%&: A third subfield with the authenticated sender,
+colon-separated, is appended to the A= item for a message arrival or delivery
+log line, if an AUTH argument to the SMTP MAIL command (see &<<SECTauthparamail>>&)
+was accepted or used.
+.next

 .cindex "log" "SMTP protocol error"
 .cindex "SMTP" "logging protocol error"
 &%smtp_protocol_error%&: A log line is written for every SMTP protocol error
 .cindex "log" "SMTP protocol error"
 .cindex "SMTP" "logging protocol error"
 &%smtp_protocol_error%&: A log line is written for every SMTP protocol error


@@ -35554,6 +35625,50 @@ are given in chapter &<<CHAPappendfile>>&.
 
 
 
 
 
 

+.section "Running local commands" "SECTsecconslocalcmds"
+There are a number of ways in which an administrator can configure Exim to run
+commands based upon received, untrustworthy, data. Further, in some
+configurations a user who can control a &_.forward_& file can also arrange to
+run commands. Configuration to check includes, but is not limited to:
+
+.ilist
+Use of &%use_shell%& in the pipe transport: various forms of shell command
+injection may be possible with this option present. It is dangerous and should
+be used only with considerable caution. Consider constraints which whitelist
+allowed characters in a variable which is to be used in a pipe transport that
+has &%use_shell%& enabled.
+.next
+A number of options such as &%forbid_filter_run%&, &%forbid_filter_perl%&,
+&%forbid_filter_dlfunc%& and so forth which restrict facilities available to
+&_.forward_& files in a redirect router. If Exim is running on a central mail
+hub to which ordinary users do not have shell access, but home directories are
+NFS mounted (for instance) then administrators should review the list of these
+forbid options available, and should bear in mind that the options that may
+need forbidding can change as new features are added between releases.
+.next
+The &%${run...}%& expansion item does not use a shell by default, but
+administrators can configure use of &_/bin/sh_& as part of the command.
+Such invocations should be viewed with prejudicial suspicion.
+.next
+Administrators who use embedded Perl are advised to explore how Perl's
+taint checking might apply to their usage.
+.next
+Use of &%${expand...}%& is somewhat analagous to shell's eval builtin and
+administrators are well advised to view its use with suspicion, in case (for
+instance) it allows a local-part to contain embedded Exim directives.
+.next
+Use of &%${match_local_part...}%& and friends becomes more dangerous if
+Exim was built with EXPAND_LISTMATCH_RHS defined: the second string in
+each can reference arbitrary lists and files, rather than just being a list
+of opaque strings.
+The EXPAND_LISTMATCH_RHS option was added and set false by default because of
+real-world security vulnerabilities caused by its use with untrustworthy data
+injected in, for SQL injection attacks.
+Consider the use of the &%inlisti%& expansion condition instead.
+.endlist
+
+
+

 .section "IPv4 source routing" "SECID272"
 .cindex "source routing" "in IP packets"
 .cindex "IP source routing"
 .section "IPv4 source routing" "SECID272"
 .cindex "source routing" "in IP packets"
 .cindex "IP source routing"


@@ -36308,6 +36423,12 @@ Add to &_src/config.h.defaults_& the line:
 Edit &_src/drtables.c_&, adding conditional code to pull in the private header
 and create a table entry as is done for all the other drivers and lookup types.
 .next
 Edit &_src/drtables.c_&, adding conditional code to pull in the private header
 and create a table entry as is done for all the other drivers and lookup types.
 .next

+Edit &_scripts/lookups-Makefile_& if this is a new lookup; there is a for-loop
+near the bottom, ranging the &`name_mod`& variable over a list of all lookups.
+Add your &`NEWDRIVER`& to that list.
+As long as the dynamic module would be named &_newdriver.so_&, you can use the
+simple form that most lookups have.
+.next

 Edit &_Makefile_& in the appropriate sub-directory (&_src/routers_&,
 &_src/transports_&, &_src/auths_&, or &_src/lookups_&); add a line for the new
 driver or lookup type and add it to the definition of OBJ.
 Edit &_Makefile_& in the appropriate sub-directory (&_src/routers_&,
 &_src/transports_&, &_src/auths_&, or &_src/lookups_&); add a line for the new
 driver or lookup type and add it to the definition of OBJ.