xref: /netbsd/src/external/ibm-public/postfix/dist/src/local/local.c

/*        $NetBSD: local.c,v 1.5 2025/02/25 19:15:46 christos Exp $   */

/*++
/* NAME
/*        local 8
/* SUMMARY
/*        Postfix local mail delivery
/* SYNOPSIS
/*        \fBlocal\fR [generic Postfix daemon options]
/* DESCRIPTION
/*        The \fBlocal\fR(8) daemon processes delivery requests from the
/*        Postfix queue manager to deliver mail to local recipients.
/*        Each delivery request specifies a queue file, a sender address,
/*        a domain or host to deliver to, and one or more recipients.
/*        This program expects to be run from the \fBmaster\fR(8) process
/*        manager.
/*
/*        The \fBlocal\fR(8) daemon updates queue files and marks recipients
/*        as finished, or it informs the queue manager that delivery should
/*        be tried again at a later time. Delivery status reports are sent
/*        to the \fBbounce\fR(8), \fBdefer\fR(8) or \fBtrace\fR(8) daemon as
/*        appropriate.
/* CASE FOLDING
/* .ad
/* .fi
/*        All delivery decisions are made using the bare recipient
/*        name (i.e. the address localpart), folded to lower case.
/*        See also under ADDRESS EXTENSION below for a few exceptions.
/* SYSTEM-WIDE AND USER-LEVEL ALIASING
/* .ad
/* .fi
/*        The system administrator can set up one or more system-wide
/*        \fBsendmail\fR-style alias databases.
/*        Users can have \fBsendmail\fR-style ~/.\fBforward\fR files.
/*        Mail for \fIname\fR is delivered to the alias \fIname\fR, to
/*        destinations in ~\fIname\fR/.\fBforward\fR, to the mailbox owned
/*        by the user \fIname\fR, or it is sent back as undeliverable.
/*
/*        The system administrator can specify a comma/space separated list
/*        of ~\fR/.\fBforward\fR like files through the \fBforward_path\fR
/*        configuration parameter. Upon delivery, the local delivery agent
/*        tries each pathname in the list until a file is found.
/*
/*        Delivery via ~/.\fBforward\fR files is done with the privileges
/*        of the recipient.
/*        Thus, ~/.\fBforward\fR like files must be readable by the
/*        recipient, and their parent directory needs to have "execute"
/*        permission for the recipient.
/*
/*        The \fBforward_path\fR parameter is subject to interpolation of
/*        \fB$user\fR (recipient username), \fB$home\fR (recipient home
/*        directory), \fB$shell\fR (recipient shell), \fB$recipient\fR
/*        (complete recipient address), \fB$extension\fR (recipient address
/*        extension), \fB$domain\fR (recipient domain), \fB$local\fR
/*        (entire recipient address localpart) and
/*        \fB$recipient_delimiter.\fR The forms \fI${name?value}\fR
/*        and \fI${name?{value}}\fR (Postfix 3.0 and later) expand
/*        conditionally to \fIvalue\fR when \fI$name\fR is defined,
/*        and the forms \fI${name:value}\fR \fI${name:{value}}\fR
/*        (Postfix 3.0 and later) expand conditionally to \fIvalue\fR
/*        when \fI$name\fR is not defined.  The form
/*        \fI${name?{value1}:{value2}}\fR (Postfix 3.0 and later)
/*        expands conditionally to \fIvalue1\fR when \fI$name\fR is
/*        defined, or \fIvalue2\fR otherwise. Characters that may
/*        have special meaning to the shell or file system are replaced
/*        with underscores. The list of acceptable characters is
/*        specified with the \fBforward_expansion_filter\fR configuration
/*        parameter.
/*
/*        An alias or ~/.\fBforward\fR file may list any combination of external
/*        commands, destination file names, \fB:include:\fR directives, or
/*        mail addresses.
/*        See \fBaliases\fR(5) for a precise description. Each line in a
/*        user's .\fBforward\fR file has the same syntax as the right-hand part
/*        of an alias.
/*
/*        When an address is found in its own alias expansion, delivery is
/*        made to the user instead. When a user is listed in the user's own
/*        ~/.\fBforward\fR file, delivery is made to the user's mailbox instead.
/*        An empty ~/.\fBforward\fR file means do not forward mail.
/*
/*        In order to prevent the mail system from using up unreasonable
/*        amounts of memory, input records read from \fB:include:\fR or from
/*        ~/.\fBforward\fR files are broken up into chunks of length
/*        \fBline_length_limit\fR.
/*
/*        While expanding aliases, ~/.\fBforward\fR files, and so on, the
/*        program attempts to avoid duplicate deliveries. The
/*        \fBduplicate_filter_limit\fR configuration parameter limits the
/*        number of remembered recipients.
/* MAIL FORWARDING
/* .ad
/* .fi
/*        For the sake of reliability, forwarded mail is re-submitted as
/*        a new message, so that each recipient has a separate on-file
/*        delivery status record.
/*
/*        In order to stop mail forwarding loops early, the software adds an
/*        optional
/*        \fBDelivered-To:\fR header with the final envelope recipient address. If
/*        mail arrives for a recipient that is already listed in a
/*        \fBDelivered-To:\fR header, the message is bounced.
/* MAILBOX DELIVERY
/* .ad
/* .fi
/*        The default per-user mailbox is a file in the UNIX mail spool
/*        directory (\fB/var/mail/\fIuser\fR or \fB/var/spool/mail/\fIuser\fR);
/*        the location can be specified with the \fBmail_spool_directory\fR
/*        configuration parameter. Specify a name ending in \fB/\fR for
/*        \fBqmail\fR-compatible \fBmaildir\fR delivery.
/*
/*        Alternatively, the per-user mailbox can be a file in the user's home
/*        directory with a name specified via the \fBhome_mailbox\fR
/*        configuration parameter. Specify a relative path name. Specify a name
/*        ending in \fB/\fR for \fBqmail\fR-compatible \fBmaildir\fR delivery.
/*
/*        Mailbox delivery can be delegated to an external command specified
/*        with the \fBmailbox_command_maps\fR and \fBmailbox_command\fR
/*        configuration parameters. The command
/*        executes with the privileges of the recipient user (exceptions:
/*        secondary groups are not enabled; in case of delivery as root,
/*        the command executes with the privileges of \fBdefault_privs\fR).
/*
/*        Mailbox delivery can be delegated to alternative message transports
/*        specified in the \fBmaster.cf\fR file.
/*        The \fBmailbox_transport_maps\fR and \fBmailbox_transport\fR
/*        configuration parameters specify an optional
/*        message transport that is to be used for all local recipients,
/*        regardless of whether they are found in the UNIX passwd database.
/*        The \fBfallback_transport_maps\fR and
/*        \fBfallback_transport\fR parameters specify an optional
/*        message transport
/*        for recipients that are not found in the aliases(5) or UNIX
/*        passwd database.
/*
/*        In the case of UNIX-style mailbox delivery,
/*        the \fBlocal\fR(8) daemon prepends a "\fBFrom \fIsender time_stamp\fR"
/*        envelope header to each message, prepends an
/*        \fBX-Original-To:\fR header with the recipient address as given to
/*        Postfix, prepends an
/*        optional \fBDelivered-To:\fR header
/*        with the final envelope recipient address, prepends a \fBReturn-Path:\fR
/*        header with the envelope sender address, prepends a \fB>\fR character
/*        to lines beginning with "\fBFrom \fR", and appends an empty line.
/*        The mailbox is locked for exclusive access while delivery is in
/*        progress. In case of problems, an attempt is made to truncate the
/*        mailbox to its original length.
/*
/*        In the case of \fBmaildir\fR delivery, the local daemon prepends
/*        an optional
/*        \fBDelivered-To:\fR header with the final envelope recipient address,
/*        prepends an
/*        \fBX-Original-To:\fR header with the recipient address as given to
/*        Postfix,
/*        and prepends a \fBReturn-Path:\fR header with the envelope sender
/*        address.
/* EXTERNAL COMMAND DELIVERY
/* .ad
/* .fi
/*        The \fBallow_mail_to_commands\fR configuration parameter restricts
/*        delivery to external commands. The default setting (\fBalias,
/*        forward\fR) forbids command destinations in \fB:include:\fR files.
/*
/*        Optionally, the process working directory is changed to the path
/*        specified with \fBcommand_execution_directory\fR (Postfix 2.2 and
/*        later). Failure to change directory causes mail to be deferred.
/*
/*        The \fBcommand_execution_directory\fR parameter value is subject
/*        to interpolation of \fB$user\fR (recipient username),
/*        \fB$home\fR (recipient home directory), \fB$shell\fR
/*        (recipient shell), \fB$recipient\fR (complete recipient
/*        address), \fB$extension\fR (recipient address extension),
/*        \fB$domain\fR (recipient domain), \fB$local\fR (entire
/*        recipient address localpart) and \fB$recipient_delimiter.\fR
/*        The forms \fI${name?value}\fR and \fI${name?{value}}\fR
/*        (Postfix 3.0 and later) expand conditionally to \fIvalue\fR
/*        when \fI$name\fR is defined, and the forms \fI${name:value}\fR
/*        and \fI${name:{value}}\fR (Postfix 3.0 and later) expand
/*        conditionally to \fIvalue\fR when \fI$name\fR is not defined.
/*        The form \fI${name?{value1}:{value2}}\fR (Postfix 3.0 and
/*        later) expands conditionally to \fIvalue1\fR when \fI$name\fR
/*        is defined, or \fIvalue2\fR otherwise. Characters that may
/*        have special meaning to the shell or file system are replaced
/*        with underscores. The list of acceptable characters
/*        is specified with the \fBexecution_directory_expansion_filter\fR
/*        configuration parameter.
/*
/*        The command is executed directly where possible. Assistance by the
/*        shell (\fB/bin/sh\fR on UNIX systems) is used only when the command
/*        contains shell magic characters, or when the command invokes a shell
/*        built-in command.
/*
/*        A limited amount of command output (standard output and standard
/*        error) is captured for inclusion with non-delivery status reports.
/*        A command is forcibly terminated if it does not complete within
/*        \fBcommand_time_limit\fR seconds.  Command exit status codes are
/*        expected to follow the conventions defined in <\fBsysexits.h\fR>.
/*        Exit status 0 means normal successful completion.
/*
/*        Postfix version 2.3 and later support RFC 3463-style enhanced
/*        status codes.  If a command terminates with a non-zero exit
/*        status, and the command output begins with an enhanced
/*        status code, this status code takes precedence over the
/*        non-zero exit status.
/*
/*        A limited amount of message context is exported via environment
/*        variables. Characters that may have special meaning to the shell
/*        are replaced with underscores.  The list of acceptable characters
/*        is specified with the \fBcommand_expansion_filter\fR configuration
/*        parameter.
/* .IP \fBSHELL\fR
/*        The envelope recipient user's login shell.
/* .IP \fBHOME\fR
/*        The envelope recipient user's home directory.
/* .IP \fBUSER\fR
/*        The bare envelope recipient name.
/* .IP \fBEXTENSION\fR
/*        The optional envelope recipient address extension.
/* .IP \fBDOMAIN\fR
/*        The envelope recipient address domain part.
/* .IP \fBLOGNAME\fR
/*        The bare envelope recipient name.
/* .IP \fBLOCAL\fR
/*        The entire envelope recipient address localpart (text to
/*        the left of the rightmost @ character).
/* .IP \fBORIGINAL_RECIPIENT\fR
/*        The entire envelope recipient address, before any address
/*        rewriting or aliasing (Postfix 2.5 and later).
/* .IP \fBRECIPIENT\fR
/*        The entire envelope recipient address.
/* .IP \fBSENDER\fR
/*        The entire envelope sender address.
/* .IP \fBENVID\fR
/*        The optional RFC 3461 envelope ID. Available as of Postfix
/*        3.9.
/* .PP
/*        Additional remote client information is made available via
/*        the following environment variables:
/* .IP \fBCLIENT_ADDRESS\fR
/*        Remote client network address. Available as of Postfix 2.2.
/* .IP \fBCLIENT_HELO\fR
/*        Remote client EHLO command parameter. Available as of Postfix 2.2.
/* .IP \fBCLIENT_HOSTNAME\fR
/*        Remote client hostname. Available as of Postfix 2.2.
/* .IP \fBCLIENT_PROTOCOL\fR
/*        Remote client protocol. Available as of Postfix 2.2.
/* .IP \fBSASL_METHOD\fR
/*        SASL authentication method specified in the
/*        remote client AUTH command. Available as of Postfix 2.2.
/* .IP \fBSASL_SENDER\fR
/*        SASL sender address specified in the remote client MAIL
/*        FROM command. Available as of Postfix 2.2.
/* .IP \fBSASL_USERNAME\fR
/*        SASL username specified in the remote client AUTH command.
/*        Available as of Postfix 2.2.
/* .PP
/*        The \fBPATH\fR environment variable is always reset to a
/*        system-dependent default path, and environment variables
/*        whose names are blessed by the \fBexport_environment\fR
/*        configuration parameter are exported unchanged.
/*
/*        The current working directory is the mail queue directory.
/*
/*        The \fBlocal\fR(8) daemon prepends a "\fBFrom \fIsender time_stamp\fR"
/*        envelope header to each message, prepends an
/*        \fBX-Original-To:\fR header with the recipient address as given to
/*        Postfix, prepends an
/*        optional \fBDelivered-To:\fR
/*        header with the final recipient envelope address, prepends a
/*        \fBReturn-Path:\fR header with the sender envelope address,
/*        and appends no empty line.
/* EXTERNAL FILE DELIVERY
/* .ad
/* .fi
/*        The delivery format depends on the destination filename syntax.
/*        The default is to use UNIX-style mailbox format.  Specify a name
/*        ending in \fB/\fR for \fBqmail\fR-compatible \fBmaildir\fR delivery.
/*
/*        The \fBallow_mail_to_files\fR configuration parameter restricts
/*        delivery to external files. The default setting (\fBalias,
/*        forward\fR) forbids file destinations in \fB:include:\fR files.
/*
/*        In the case of UNIX-style mailbox delivery,
/*        the \fBlocal\fR(8) daemon prepends a "\fBFrom \fIsender time_stamp\fR"
/*        envelope header to each message, prepends an
/*        \fBX-Original-To:\fR header with the recipient address as given to
/*        Postfix, prepends an
/*        optional \fBDelivered-To:\fR
/*        header with the final recipient envelope address, prepends a \fB>\fR
/*        character to lines beginning with "\fBFrom \fR", and appends an
/*        empty line.
/*        The envelope sender address is available in the \fBReturn-Path:\fR
/*        header.
/*        When the destination is a regular file, it is locked for exclusive
/*        access while delivery is in progress. In case of problems, an attempt
/*        is made to truncate a regular file to its original length.
/*
/*        In the case of \fBmaildir\fR delivery, the local daemon prepends
/*        an optional
/*        \fBDelivered-To:\fR header with the final envelope recipient address,
/*        and prepends an
/*        \fBX-Original-To:\fR header with the recipient address as given to
/*        Postfix.
/*        The envelope sender address is available in the \fBReturn-Path:\fR
/*        header.
/* ADDRESS EXTENSION
/* .ad
/* .fi
/*        The optional \fBrecipient_delimiter\fR configuration parameter
/*        specifies how to separate address extensions from local recipient
/*        names.
/*
/*        For example, with "\fBrecipient_delimiter = +\fR", mail for
/*        \fIname\fR+\fIfoo\fR is delivered to the alias \fIname\fR+\fIfoo\fR
/*        or to the alias \fIname\fR, to the destinations listed in
/*        ~\fIname\fR/.\fBforward\fR+\fIfoo\fR or in ~\fIname\fR/.\fBforward\fR,
/*        to the mailbox owned by the user \fIname\fR, or it is sent back as
/*        undeliverable.
/* DELIVERY RIGHTS
/* .ad
/* .fi
/*        Deliveries to external files and external commands are made with
/*        the rights of the receiving user on whose behalf the delivery is made.
/*        In the absence of a user context, the \fBlocal\fR(8) daemon uses the
/*        owner rights of the \fB:include:\fR file or alias database.
/*        When those files are owned by the superuser, delivery is made with
/*        the rights specified with the \fBdefault_privs\fR configuration
/*        parameter.
/* STANDARDS
/*        RFC 822 (ARPA Internet Text Messages)
/*        RFC 3463 (Enhanced status codes)
/* DIAGNOSTICS
/*        Problems and transactions are logged to \fBsyslogd\fR(8)
/*        or \fBpostlogd\fR(8).
/*        Corrupted message files are marked so that the queue
/*        manager can move them to the \fBcorrupt\fR queue afterwards.
/*
/*        Depending on the setting of the \fBnotify_classes\fR parameter,
/*        the postmaster is notified of bounces and of other trouble.
/* SECURITY
/* .ad
/* .fi
/*        The \fBlocal\fR(8) delivery agent needs a dual personality
/*        1) to access the private Postfix queue and IPC mechanisms,
/*        2) to impersonate the recipient and deliver to recipient-specified
/*        files or commands. It is therefore security sensitive.
/*
/*        The \fBlocal\fR(8) delivery agent disallows regular expression
/*        substitution of $1 etc. in \fBalias_maps\fR, because that
/*        would open a security hole.
/*
/*        The \fBlocal\fR(8) delivery agent will silently ignore
/*        requests to use the \fBproxymap\fR(8) server within
/*        \fBalias_maps\fR. Instead it will open the table directly.
/*        Before Postfix version 2.2, the \fBlocal\fR(8) delivery
/*        agent will terminate with a fatal error.
/* BUGS
/*        For security reasons, the message delivery status of external commands
/*        or of external files is never checkpointed to file. As a result,
/*        the program may occasionally deliver more than once to a command or
/*        external file. Better safe than sorry.
/*
/*        Mutually-recursive aliases or ~/.\fBforward\fR files are not detected
/*        early.  The resulting mail forwarding loop is broken by the use of the
/*        \fBDelivered-To:\fR message header.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/*        Changes to \fBmain.cf\fR are picked up automatically, as \fBlocal\fR(8)
/*        processes run for only a limited amount of time. Use the command
/*        "\fBpostfix reload\fR" to speed up a change.
/*
/*        The text below provides only a parameter summary. See
/*        \fBpostconf\fR(5) for more details including examples.
/* COMPATIBILITY CONTROLS
/* .ad
/* .fi
/* .IP "\fBbiff (yes)\fR"
/*        Whether or not to use the local biff service.
/* .IP "\fBexpand_owner_alias (no)\fR"
/*        When delivering to an alias "\fIaliasname\fR" that has an
/*        "owner-\fIaliasname\fR" companion alias, set the envelope sender
/*        address to the expansion of the "owner-\fIaliasname\fR" alias.
/* .IP "\fBowner_request_special (yes)\fR"
/*        Enable special treatment for owner-\fIlistname\fR entries in the
/*        \fBaliases\fR(5) file, and don't split owner-\fIlistname\fR and
/*        \fIlistname\fR-request address localparts when the recipient_delimiter
/*        is set to "-".
/* .IP "\fBsun_mailtool_compatibility (no)\fR"
/*        Obsolete SUN mailtool compatibility feature.
/* .PP
/*        Available in Postfix version 2.3 and later:
/* .IP "\fBfrozen_delivered_to (yes)\fR"
/*        Update the \fBlocal\fR(8) delivery agent's idea of the Delivered-To:
/*        address (see prepend_delivered_header) only once, at the start of
/*        a delivery attempt; do not update the Delivered-To: address while
/*        expanding aliases or .forward files.
/* .PP
/*        Available in Postfix version 2.5.3 and later:
/* .IP "\fBstrict_mailbox_ownership (yes)\fR"
/*        Defer delivery when a mailbox file is not owned by its recipient.
/* .IP "\fBreset_owner_alias (no)\fR"
/*        Reset the \fBlocal\fR(8) delivery agent's idea of the owner-alias
/*        attribute, when delivering mail to a child alias that does not have
/*        its own owner alias.
/* .PP
/*        Available in Postfix version 3.0 and later:
/* .IP "\fBlocal_delivery_status_filter ($default_delivery_status_filter)\fR"
/*        Optional filter for the \fBlocal\fR(8) delivery agent to change the
/*        status code or explanatory text of successful or unsuccessful
/*        deliveries.
/* DELIVERY METHOD CONTROLS
/* .ad
/* .fi
/*        The precedence of \fBlocal\fR(8) delivery methods from high to low is:
/*        aliases, .forward files, mailbox_transport_maps,
/*        mailbox_transport, mailbox_command_maps, mailbox_command,
/*        home_mailbox, mail_spool_directory, fallback_transport_maps,
/*        fallback_transport, and luser_relay.
/* .IP "\fBalias_maps (see 'postconf -d' output)\fR"
/*        Optional lookup tables that are searched only with an email address
/*        localpart (no domain) and that apply only to \fBlocal\fR(8) recipients;
/*        this is unlike virtual_alias_maps that are often searched with a
/*        full email address (including domain) and that apply to all recipients:
/*        \fBlocal\fR(8), virtual, and remote.
/* .IP "\fBforward_path (see 'postconf -d' output)\fR"
/*        The \fBlocal\fR(8) delivery agent search list for finding a .forward
/*        file with user-specified delivery methods.
/* .IP "\fBmailbox_transport_maps (empty)\fR"
/*        Optional lookup tables with per-recipient message delivery
/*        transports to use for \fBlocal\fR(8) mailbox delivery, whether or not the
/*        recipients are found in the UNIX passwd database.
/* .IP "\fBmailbox_transport (empty)\fR"
/*        Optional message delivery transport that the \fBlocal\fR(8) delivery
/*        agent should use for mailbox delivery to all local recipients,
/*        whether or not they are found in the UNIX passwd database.
/* .IP "\fBmailbox_command_maps (empty)\fR"
/*        Optional lookup tables with per-recipient external commands to use
/*        for \fBlocal\fR(8) mailbox delivery.
/* .IP "\fBmailbox_command (empty)\fR"
/*        Optional external command that the \fBlocal\fR(8) delivery agent should
/*        use for mailbox delivery.
/* .IP "\fBhome_mailbox (empty)\fR"
/*        Optional pathname of a mailbox file relative to a \fBlocal\fR(8) user's
/*        home directory.
/* .IP "\fBmail_spool_directory (see 'postconf -d' output)\fR"
/*        The directory where \fBlocal\fR(8) UNIX-style mailboxes are kept.
/* .IP "\fBfallback_transport_maps (empty)\fR"
/*        Optional lookup tables with per-recipient message delivery
/*        transports for recipients that the \fBlocal\fR(8) delivery agent could
/*        not find in the \fBaliases\fR(5) or UNIX password database.
/* .IP "\fBfallback_transport (empty)\fR"
/*        Optional message delivery transport that the \fBlocal\fR(8) delivery
/*        agent should use for names that are not found in the \fBaliases\fR(5)
/*        or UNIX password database.
/* .IP "\fBluser_relay (empty)\fR"
/*        Optional catch-all destination for unknown \fBlocal\fR(8) recipients.
/* .PP
/*        Available in Postfix version 2.2 and later:
/* .IP "\fBcommand_execution_directory (empty)\fR"
/*        The \fBlocal\fR(8) delivery agent working directory for delivery to
/*        external commands.
/* MAILBOX LOCKING CONTROLS
/* .ad
/* .fi
/* .IP "\fBdeliver_lock_attempts (20)\fR"
/*        The maximal number of attempts to acquire an exclusive lock on a
/*        mailbox file or \fBbounce\fR(8) logfile.
/* .IP "\fBdeliver_lock_delay (1s)\fR"
/*        The time between attempts to acquire an exclusive lock on a mailbox
/*        file or \fBbounce\fR(8) logfile.
/* .IP "\fBstale_lock_time (500s)\fR"
/*        The time after which a stale exclusive mailbox lockfile is removed.
/* .IP "\fBmailbox_delivery_lock (see 'postconf -d' output)\fR"
/*        How to lock a UNIX-style \fBlocal\fR(8) mailbox before attempting delivery.
/* RESOURCE AND RATE CONTROLS
/* .ad
/* .fi
/* .IP "\fBcommand_time_limit (1000s)\fR"
/*        Time limit for delivery to external commands.
/* .IP "\fBduplicate_filter_limit (1000)\fR"
/*        The maximal number of addresses remembered by the address
/*        duplicate filter for \fBaliases\fR(5) or \fBvirtual\fR(5) alias expansion, or
/*        for \fBshowq\fR(8) queue displays.
/* .IP "\fBmailbox_size_limit (51200000)\fR"
/*        The maximal size of any \fBlocal\fR(8) individual mailbox or maildir
/*        file, or zero (no limit).
/* .PP
/*        Implemented in the qmgr(8) daemon:
/* .IP "\fBlocal_destination_concurrency_limit (2)\fR"
/*        The maximal number of parallel deliveries via the local mail
/*        delivery transport to the same recipient (when
/*        "local_destination_recipient_limit = 1") or the maximal number of
/*        parallel deliveries to the same local domain (when
/*        "local_destination_recipient_limit > 1").
/* .IP "\fBlocal_destination_recipient_limit (1)\fR"
/*        The maximal number of recipients per message delivery via the
/*        local mail delivery transport.
/* SECURITY CONTROLS
/* .ad
/* .fi
/* .IP "\fBallow_mail_to_commands (alias, forward)\fR"
/*        Restrict \fBlocal\fR(8) mail delivery to external commands.
/* .IP "\fBallow_mail_to_files (alias, forward)\fR"
/*        Restrict \fBlocal\fR(8) mail delivery to external files.
/* .IP "\fBcommand_expansion_filter (see 'postconf -d' output)\fR"
/*        Restrict the characters that the \fBlocal\fR(8) delivery agent allows in
/*        $name expansions of $mailbox_command and $command_execution_directory.
/* .IP "\fBdefault_privs (nobody)\fR"
/*        The default rights used by the \fBlocal\fR(8) delivery agent for delivery
/*        to an external file or command.
/* .IP "\fBforward_expansion_filter (see 'postconf -d' output)\fR"
/*        Restrict the characters that the \fBlocal\fR(8) delivery agent allows in
/*        $name expansions of $forward_path.
/* .PP
/*        Available in Postfix version 2.2 and later:
/* .IP "\fBexecution_directory_expansion_filter (see 'postconf -d' output)\fR"
/*        Restrict the characters that the \fBlocal\fR(8) delivery agent allows
/*        in $name expansions of $command_execution_directory.
/* .PP
/*        Available in Postfix version 2.5.3 and later:
/* .IP "\fBstrict_mailbox_ownership (yes)\fR"
/*        Defer delivery when a mailbox file is not owned by its recipient.
/* MISCELLANEOUS CONTROLS
/* .ad
/* .fi
/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
/*        The default location of the Postfix main.cf and master.cf
/*        configuration files.
/* .IP "\fBdaemon_timeout (18000s)\fR"
/*        How much time a Postfix daemon process may take to handle a
/*        request before it is terminated by a built-in watchdog timer.
/* .IP "\fBdelay_logging_resolution_limit (2)\fR"
/*        The maximal number of digits after the decimal point when logging
/*        delay values.
/* .IP "\fBexport_environment (see 'postconf -d' output)\fR"
/*        The list of environment variables that a Postfix process will export
/*        to non-Postfix processes.
/* .IP "\fBipc_timeout (3600s)\fR"
/*        The time limit for sending or receiving information over an internal
/*        communication channel.
/* .IP "\fBlocal_command_shell (empty)\fR"
/*        Optional shell program for \fBlocal\fR(8) delivery to non-Postfix commands.
/* .IP "\fBmax_idle (100s)\fR"
/*        The maximum amount of time that an idle Postfix daemon process waits
/*        for an incoming connection before terminating voluntarily.
/* .IP "\fBmax_use (100)\fR"
/*        The maximal number of incoming connections that a Postfix daemon
/*        process will service before terminating voluntarily.
/* .IP "\fBprepend_delivered_header (command, file, forward)\fR"
/*        The message delivery contexts where the Postfix \fBlocal\fR(8) delivery
/*        agent prepends a Delivered-To:  message header with the address
/*        that the mail was delivered to.
/* .IP "\fBprocess_id (read-only)\fR"
/*        The process ID of a Postfix command or daemon process.
/* .IP "\fBprocess_name (read-only)\fR"
/*        The process name of a Postfix command or daemon process.
/* .IP "\fBpropagate_unmatched_extensions (canonical, virtual)\fR"
/*        What address lookup tables copy an address extension from the lookup
/*        key to the lookup result.
/* .IP "\fBqueue_directory (see 'postconf -d' output)\fR"
/*        The location of the Postfix top-level queue directory.
/* .IP "\fBrecipient_delimiter (empty)\fR"
/*        The set of characters that can separate an email address
/*        localpart, user name, or a .forward file name from its extension.
/* .IP "\fBrequire_home_directory (no)\fR"
/*        Require that a \fBlocal\fR(8) recipient's home directory exists
/*        before mail delivery is attempted.
/* .IP "\fBsyslog_facility (mail)\fR"
/*        The syslog facility of Postfix logging.
/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
/*        A prefix that is prepended to the process name in syslog
/*        records, so that, for example, "smtpd" becomes "prefix/smtpd".
/* .PP
/*        Available in Postfix version 3.3 and later:
/* .IP "\fBenable_original_recipient (yes)\fR"
/*        Enable support for the original recipient address after an
/*        address is rewritten to a different address (for example with
/*        aliasing or with canonical mapping).
/* .IP "\fBservice_name (read-only)\fR"
/*        The master.cf service name of a Postfix daemon process.
/* .PP
/*        Available in Postfix 3.5 and later:
/* .IP "\fBinfo_log_address_format (external)\fR"
/*        The email address form that will be used in non-debug logging
/*        (info, warning, etc.).
/* FILES
/*        The following are examples; details differ between systems.
/*        $HOME/.forward, per-user aliasing
/*        /etc/aliases, system-wide alias database
/*        /var/spool/mail, system mailboxes
/* SEE ALSO
/*        qmgr(8), queue manager
/*        bounce(8), delivery status reports
/*        newaliases(1), create/update alias database
/*        postalias(1), create/update alias database
/*        aliases(5), format of alias database
/*        postconf(5), configuration parameters
/*        master(5), generic daemon options
/*        postlogd(8), Postfix logging
/*        syslogd(8), system logging
/* LICENSE
/* .ad
/* .fi
/*        The Secure Mailer license must be distributed with this software.
/* HISTORY
/* .ad
/* .fi
/*        The \fBDelivered-To:\fR message header appears in the \fBqmail\fR
/*        system by Daniel Bernstein.
/*
/*        The \fImaildir\fR structure appears in the \fBqmail\fR system
/*        by Daniel Bernstein.
/* AUTHOR(S)
/*        Wietse Venema
/*        IBM T.J. Watson Research
/*        P.O. Box 704
/*        Yorktown Heights, NY 10598, USA
/*
/*        Wietse Venema
/*        Google, Inc.
/*        111 8th Avenue
/*        New York, NY 10011, USA
/*
/*        Wietse Venema
/*        porcupine.org
/*--*/

/* System library. */

#include <sys_defs.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#ifdef USE_PATHS_H
#include <paths.h>
#endif

/* Utility library. */

#include <msg.h>
#include <mymalloc.h>
#include <htable.h>
#include <vstring.h>
#include <vstream.h>
#include <iostuff.h>
#include <name_mask.h>
#include <set_eugid.h>
#include <dict.h>

/* Global library. */

#include <recipient_list.h>
#include <deliver_request.h>
#include <deliver_completed.h>
#include <mail_params.h>
#include <mail_addr.h>
#include <mail_conf.h>
#include <been_here.h>
#include <mail_params.h>
#include <mail_version.h>
#include <ext_prop.h>
#include <maps.h>
#include <flush_clnt.h>

/* Single server skeleton. */

#include <mail_server.h>

/* Application-specific. */

#include "local.h"

 /*
  * Tunable parameters.
  */
char   *var_allow_commands;
char   *var_allow_files;
char   *var_alias_maps;
int     var_dup_filter_limit;
int     var_command_maxtime;            /* You can now leave this here. */
char   *var_home_mailbox;
char   *var_mailbox_command;
char   *var_mailbox_cmd_maps;
char   *var_rcpt_fdelim;
char   *var_local_cmd_shell;
char   *var_luser_relay;
int     var_biff;
char   *var_mail_spool_dir;
char   *var_mailbox_transport;
char   *var_mbox_transp_maps;
char   *var_fallback_transport;
char   *var_fbck_transp_maps;
char   *var_exec_directory;
char   *var_exec_exp_filter;
char   *var_forward_path;
char   *var_cmd_exp_filter;
char   *var_fwd_exp_filter;
char   *var_prop_extension;
int     var_exp_own_alias;
char   *var_deliver_hdr;
int     var_stat_home_dir;
int     var_mailtool_compat;
char   *var_mailbox_lock;
long    var_mailbox_limit;
bool    var_frozen_delivered;
bool    var_reset_owner_attr;
bool    var_strict_mbox_owner;

int     local_cmd_deliver_mask;
int     local_file_deliver_mask;
int     local_ext_prop_mask;
int     local_deliver_hdr_mask;
int     local_mbox_lock_mask;
MAPS   *alias_maps;
char   *var_local_dsn_filter;

/* local_deliver - deliver message with extreme prejudice */

static int local_deliver(DELIVER_REQUEST *rqst, char *service)
{
    const char *myname = "local_deliver";
    RECIPIENT *rcpt_end = rqst->rcpt_list.info + rqst->rcpt_list.len;
    RECIPIENT *rcpt;
    int     rcpt_stat;
    int     msg_stat;
    LOCAL_STATE state;
    USER_ATTR usr_attr;

    if (msg_verbose)
          msg_info("local_deliver: %s from %s", rqst->queue_id, rqst->sender);

    /*
     * Initialize the delivery attributes that are not recipient specific.
     * While messages are being delivered and while aliases or forward files
     * are being expanded, this attribute list is being changed constantly.
     * For this reason, the list is passed on by value (except when it is
     * being initialized :-), so that there is no need to undo attribute
     * changes made by lower-level routines. The alias/include/forward
     * expansion attribute list is part of a tree with self and parent
     * references (see the EXPAND_ATTR definitions). The user-specific
     * attributes are security sensitive, and are therefore kept separate.
     * All this results in a noticeable level of clumsiness, but passing
     * things around by value gives good protection against accidental change
     * by subroutines.
     */
    state.level = 0;
    deliver_attr_init(&state.msg_attr);
    state.msg_attr.queue_name = rqst->queue_name;
    state.msg_attr.queue_id = rqst->queue_id;
    state.msg_attr.fp = rqst->fp;
    state.msg_attr.offset = rqst->data_offset;
    state.msg_attr.encoding = rqst->encoding;
    state.msg_attr.sendopts = rqst->sendopts;
    state.msg_attr.sender = rqst->sender;
    state.msg_attr.dsn_envid = rqst->dsn_envid;
    state.msg_attr.dsn_ret = rqst->dsn_ret;
    state.msg_attr.relay = service;
    state.msg_attr.msg_stats = rqst->msg_stats;
    state.msg_attr.request = rqst;
    RESET_OWNER_ATTR(state.msg_attr, state.level);
    RESET_USER_ATTR(usr_attr, state.level);
    state.loop_info = delivered_hdr_init(rqst->fp, rqst->data_offset,
                                                   FOLD_ADDR_ALL);
    state.request = rqst;

    /*
     * Iterate over each recipient named in the delivery request. When the
     * mail delivery status for a given recipient is definite (i.e. bounced
     * or delivered), update the message queue file and cross off the
     * recipient. Update the per-message delivery status.
     */
    for (msg_stat = 0, rcpt = rqst->rcpt_list.info; rcpt < rcpt_end; rcpt++) {
          state.dup_filter = been_here_init(var_dup_filter_limit, BH_FLAG_FOLD);
          forward_init();
          state.msg_attr.rcpt = *rcpt;
          rcpt_stat = deliver_recipient(state, usr_attr);
          rcpt_stat |= forward_finish(rqst, state.msg_attr, rcpt_stat);
          if (rcpt_stat == 0 && (rqst->flags & DEL_REQ_FLAG_SUCCESS))
              deliver_completed(state.msg_attr.fp, rcpt->offset);
          been_here_free(state.dup_filter);
          msg_stat |= rcpt_stat;
    }

    /*
     * Clean up.
     */
    delivered_hdr_free(state.loop_info);
    deliver_attr_free(&state.msg_attr);

    return (msg_stat);
}

/* local_service - perform service for client */

static void local_service(VSTREAM *stream, char *service, char **argv)
{
    DELIVER_REQUEST *request;
    int     status;

    /*
     * Sanity check. This service takes no command-line arguments.
     */
    if (argv[0])
          msg_fatal("unexpected command-line argument: %s", argv[0]);

    /*
     * This routine runs whenever a client connects to the UNIX-domain socket
     * that is dedicated to local mail delivery service. What we see below is
     * a little protocol to (1) tell the client that we are ready, (2) read a
     * delivery request from the client, and (3) report the completion status
     * of that request.
     */
    if ((request = deliver_request_read(stream)) != 0) {
          status = local_deliver(request, service);
          deliver_request_done(stream, request, status);
    }
}

/* local_mask_init - initialize delivery restrictions */

static void local_mask_init(void)
{
    static const NAME_MASK file_mask[] = {
          "alias", EXPAND_TYPE_ALIAS,
          "forward", EXPAND_TYPE_FWD,
          "include", EXPAND_TYPE_INCL,
          0,
    };
    static const NAME_MASK command_mask[] = {
          "alias", EXPAND_TYPE_ALIAS,
          "forward", EXPAND_TYPE_FWD,
          "include", EXPAND_TYPE_INCL,
          0,
    };
    static const NAME_MASK deliver_mask[] = {
          "command", DELIVER_HDR_CMD,
          "file", DELIVER_HDR_FILE,
          "forward", DELIVER_HDR_FWD,
          0,
    };

    local_file_deliver_mask = name_mask(VAR_ALLOW_FILES, file_mask,
                                                  var_allow_files);
    local_cmd_deliver_mask = name_mask(VAR_ALLOW_COMMANDS, command_mask,
                                               var_allow_commands);
    local_ext_prop_mask =
          ext_prop_mask(VAR_PROP_EXTENSION, var_prop_extension);
    local_deliver_hdr_mask = name_mask(VAR_DELIVER_HDR, deliver_mask,
                                               var_deliver_hdr);
    local_mbox_lock_mask = mbox_lock_mask(var_mailbox_lock);
    if (var_mailtool_compat) {
          msg_warn("%s: deprecated parameter, use \"%s = dotlock\" instead",
                     VAR_MAILTOOL_COMPAT, VAR_MAILBOX_LOCK);
          local_mbox_lock_mask &= MBOX_DOT_LOCK;
    }
    if (local_mbox_lock_mask == 0)
          msg_fatal("parameter %s specifies no applicable mailbox locking method",
                      VAR_MAILBOX_LOCK);
}

/* pre_accept - see if tables have changed */

static void pre_accept(char *unused_name, char **unused_argv)
{
    const char *table;

    if ((table = dict_changed_name()) != 0) {
          msg_info("table %s has changed -- restarting", table);
          exit(0);
    }
}

/* post_init - post-jail initialization */

static void post_init(char *unused_name, char **unused_argv)
{

    /*
     * Drop privileges most of the time, and set up delivery restrictions.
     */
    set_eugid(var_owner_uid, var_owner_gid);
    local_mask_init();
}

/* pre_init - pre-jail initialization */

static void pre_init(char *unused_name, char **unused_argv)
{

    /*
     * Reset the file size limit from the message size limit to the mailbox
     * size limit. XXX This still isn't accurate because the file size limit
     * also affects delivery to command.
     *
     * A file size limit protects the machine against runaway software errors.
     * It is not suitable to enforce mail quota, because users can get around
     * mail quota by delivering to /file/name or to |command.
     *
     * We can't have mailbox size limit smaller than the message size limit,
     * because that prohibits the delivery agent from updating the queue
     * file.
     */
    if (ENFORCING_SIZE_LIMIT(var_mailbox_limit)) {
          if (!ENFORCING_SIZE_LIMIT(var_message_limit))
              msg_fatal("configuration error: %s is limited but %s is "
                          "unlimited", VAR_MAILBOX_LIMIT, VAR_MESSAGE_LIMIT);
          if (var_mailbox_limit < var_message_limit)
              msg_fatal("configuration error: %s is smaller than %s",
                          VAR_MAILBOX_LIMIT, VAR_MESSAGE_LIMIT);
          set_file_limit(var_mailbox_limit);
    }
    alias_maps = maps_create("aliases", var_alias_maps,
                                   DICT_FLAG_LOCK | DICT_FLAG_PARANOID
                                   | DICT_FLAG_FOLD_FIX
                                   | DICT_FLAG_UTF8_REQUEST);

    flush_init();
}

MAIL_VERSION_STAMP_DECLARE;

/* main - pass control to the single-threaded skeleton */

int     main(int argc, char **argv)
{
    static const CONFIG_TIME_TABLE time_table[] = {
          VAR_COMMAND_MAXTIME, DEF_COMMAND_MAXTIME, &var_command_maxtime, 1, 0,
          0,
    };
    static const CONFIG_INT_TABLE int_table[] = {
          VAR_DUP_FILTER_LIMIT, DEF_DUP_FILTER_LIMIT, &var_dup_filter_limit, 0, 0,
          0,
    };
    static const CONFIG_LONG_TABLE long_table[] = {
          VAR_MAILBOX_LIMIT, DEF_MAILBOX_LIMIT, &var_mailbox_limit, 0, 0,
          0,
    };
    static const CONFIG_STR_TABLE str_table[] = {
          VAR_ALIAS_MAPS, DEF_ALIAS_MAPS, &var_alias_maps, 0, 0,
          VAR_HOME_MAILBOX, DEF_HOME_MAILBOX, &var_home_mailbox, 0, 0,
          VAR_ALLOW_COMMANDS, DEF_ALLOW_COMMANDS, &var_allow_commands, 0, 0,
          VAR_ALLOW_FILES, DEF_ALLOW_FILES, &var_allow_files, 0, 0,
          VAR_LOCAL_CMD_SHELL, DEF_LOCAL_CMD_SHELL, &var_local_cmd_shell, 0, 0,
          VAR_MAIL_SPOOL_DIR, DEF_MAIL_SPOOL_DIR, &var_mail_spool_dir, 0, 0,
          VAR_MAILBOX_TRANSP, DEF_MAILBOX_TRANSP, &var_mailbox_transport, 0, 0,
          VAR_MBOX_TRANSP_MAPS, DEF_MBOX_TRANSP_MAPS, &var_mbox_transp_maps, 0, 0,
          VAR_FALLBACK_TRANSP, DEF_FALLBACK_TRANSP, &var_fallback_transport, 0, 0,
          VAR_FBCK_TRANSP_MAPS, DEF_FBCK_TRANSP_MAPS, &var_fbck_transp_maps, 0, 0,
          VAR_CMD_EXP_FILTER, DEF_CMD_EXP_FILTER, &var_cmd_exp_filter, 1, 0,
          VAR_FWD_EXP_FILTER, DEF_FWD_EXP_FILTER, &var_fwd_exp_filter, 1, 0,
          VAR_EXEC_EXP_FILTER, DEF_EXEC_EXP_FILTER, &var_exec_exp_filter, 1, 0,
          VAR_PROP_EXTENSION, DEF_PROP_EXTENSION, &var_prop_extension, 0, 0,
          VAR_DELIVER_HDR, DEF_DELIVER_HDR, &var_deliver_hdr, 0, 0,
          VAR_MAILBOX_LOCK, DEF_MAILBOX_LOCK, &var_mailbox_lock, 1, 0,
          VAR_MAILBOX_CMD_MAPS, DEF_MAILBOX_CMD_MAPS, &var_mailbox_cmd_maps, 0, 0,
          VAR_LOCAL_DSN_FILTER, DEF_LOCAL_DSN_FILTER, &var_local_dsn_filter, 0, 0,
          0,
    };
    static const CONFIG_BOOL_TABLE bool_table[] = {
          VAR_BIFF, DEF_BIFF, &var_biff,
          VAR_EXP_OWN_ALIAS, DEF_EXP_OWN_ALIAS, &var_exp_own_alias,
          VAR_STAT_HOME_DIR, DEF_STAT_HOME_DIR, &var_stat_home_dir,
          VAR_MAILTOOL_COMPAT, DEF_MAILTOOL_COMPAT, &var_mailtool_compat,
          VAR_FROZEN_DELIVERED, DEF_FROZEN_DELIVERED, &var_frozen_delivered,
          VAR_RESET_OWNER_ATTR, DEF_RESET_OWNER_ATTR, &var_reset_owner_attr,
          VAR_STRICT_MBOX_OWNER, DEF_STRICT_MBOX_OWNER, &var_strict_mbox_owner,
          0,
    };

    /* Suppress $name expansion upon loading. */
    static const CONFIG_RAW_TABLE raw_table[] = {
          VAR_EXEC_DIRECTORY, DEF_EXEC_DIRECTORY, &var_exec_directory, 0, 0,
          VAR_FORWARD_PATH, DEF_FORWARD_PATH, &var_forward_path, 0, 0,
          VAR_MAILBOX_COMMAND, DEF_MAILBOX_COMMAND, &var_mailbox_command, 0, 0,
          VAR_LUSER_RELAY, DEF_LUSER_RELAY, &var_luser_relay, 0, 0,
          0,
    };

    /*
     * Fingerprint executables and core dumps.
     */
    MAIL_VERSION_STAMP_ALLOCATE;

    single_server_main(argc, argv, local_service,
                           CA_MAIL_SERVER_INT_TABLE(int_table),
                           CA_MAIL_SERVER_LONG_TABLE(long_table),
                           CA_MAIL_SERVER_STR_TABLE(str_table),
                           CA_MAIL_SERVER_RAW_TABLE(raw_table),
                           CA_MAIL_SERVER_BOOL_TABLE(bool_table),
                           CA_MAIL_SERVER_TIME_TABLE(time_table),
                           CA_MAIL_SERVER_PRE_INIT(pre_init),
                           CA_MAIL_SERVER_POST_INIT(post_init),
                           CA_MAIL_SERVER_PRE_ACCEPT(pre_accept),
                           CA_MAIL_SERVER_PRIVILEGED,
                           CA_MAIL_SERVER_BOUNCE_INIT(VAR_LOCAL_DSN_FILTER,
                                                              &var_local_dsn_filter),
                           0);
}