discard.c

[詳解]

/*++
/* NAME
/*  discard 8
/* SUMMARY
/*  Postfix discard mail delivery agent
/* SYNOPSIS
/*  \fBdiscard\fR [generic Postfix daemon options]
/* DESCRIPTION
/*  The Postfix \fBdiscard\fR(8) delivery agent processes
/*  delivery requests from
/*  the queue manager. Each request specifies a queue file, a sender
/*  address, a next-hop destination that is treated as the reason for
/*  discarding the mail, and recipient information.
/*  The reason may be prefixed with an RFC 3463-compatible detail code.
/*  This program expects to be run from the \fBmaster\fR(8) process
/*  manager.
/*
/*  The \fBdiscard\fR(8) delivery agent pretends to deliver all recipients
/*  in the delivery request, logs the "next-hop" destination
/*  as the reason for discarding the mail, updates the
/*  queue file, and either marks recipients as finished or informs the
/*  queue manager that delivery should be tried again at a later time.
/*
/*  Delivery status reports are sent to the \fBtrace\fR(8)
/*  daemon as appropriate.
/* SECURITY
/* .ad
/* .fi
/*  The \fBdiscard\fR(8) mailer is not security-sensitive. It does not talk
/*  to the network, and can be run chrooted at fixed low privilege.
/* STANDARDS
/*  RFC 3463 (Enhanced Status Codes)
/* DIAGNOSTICS
/*  Problems and transactions are logged to \fBsyslogd\fR(8).
/*
/*  Depending on the setting of the \fBnotify_classes\fR parameter,
/*  the postmaster is notified of bounces and of other trouble.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/*  Changes to \fBmain.cf\fR are picked up automatically as \fBdiscard\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.
/* .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
/*  sub-second delay values.
/* .IP "\fBdouble_bounce_sender (double-bounce)\fR"
/*  The sender address of postmaster notifications that are generated
/*  by the mail system.
/* .IP "\fBipc_timeout (3600s)\fR"
/*  The time limit for sending or receiving information over an internal
/*  communication channel.
/* .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 "\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 "\fBqueue_directory (see 'postconf -d' output)\fR"
/*  The location of the Postfix top-level queue directory.
/* .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 3.3 and later:
/* .IP "\fBservice_name (read-only)\fR"
/*  The master.cf service name of a Postfix daemon process.
/* SEE ALSO
/*  qmgr(8), queue manager
/*  bounce(8), delivery status reports
/*  error(8), Postfix error delivery agent
/*  postconf(5), configuration parameters
/*  master(5), generic daemon options
/*  master(8), process manager
/*  syslogd(8), system logging
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* HISTORY
/*  This service was introduced with Postfix version 2.2.
/* AUTHOR(S)
/*  Victor Duchovni
/*  Morgan Stanley
/*
/*  Based on code by:
/*  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
/*--*/

/* System library. */

#include <sys_defs.h>
#include <unistd.h>
#include <stdlib.h>

/* Utility library. */

#include <msg.h>
#include <vstream.h>

/* Global library. */

#include <deliver_request.h>
#include <mail_queue.h>
#include <bounce.h>
#include <deliver_completed.h>
#include <flush_clnt.h>
#include <sent.h>
#include <dsn_util.h>
#include <mail_version.h>

/* Single server skeleton. */

#include <mail_server.h>

/* deliver_message - deliver message with extreme prejudice */

static int deliver_message(DELIVER_REQUEST *request)
{
    const char *myname = "deliver_message";
    VSTREAM *src;
    int     result = 0;
    int     status;
    RECIPIENT *rcpt;
    int     nrcpt;
    DSN_SPLIT dp;
    DSN     dsn;

    if (msg_verbose)
    msg_info("deliver_message: from %s", request->sender);

    /*
     * Sanity checks.
     */
    if (request->nexthop[0] == 0)
    msg_fatal("empty nexthop hostname");
    if (request->rcpt_list.len <= 0)
    msg_fatal("recipient count: %d", request->rcpt_list.len);

    /*
     * Open the queue file. Opening the file can fail for a variety of
     * reasons, such as the system running out of resources. Instead of
     * throwing away mail, we're raising a fatal error which forces the mail
     * system to back off, and retry later.
     */
    src = mail_queue_open(request->queue_name, request->queue_id,
              O_RDWR, 0);
    if (src == 0)
    msg_fatal("%s: open %s %s: %m", myname,
          request->queue_name, request->queue_id);
    if (msg_verbose)
    msg_info("%s: file %s", myname, VSTREAM_PATH(src));

    /*
     * Discard all recipients.
     */
#define BOUNCE_FLAGS(request) DEL_REQ_TRACE_FLAGS(request->flags)

    dsn_split(&dp, "2.0.0", request->nexthop);
    (void) DSN_SIMPLE(&dsn, DSN_STATUS(dp.dsn), dp.text);
    for (nrcpt = 0; nrcpt < request->rcpt_list.len; nrcpt++) {
    rcpt = request->rcpt_list.info + nrcpt;
    status = sent(BOUNCE_FLAGS(request), request->queue_id,
              &request->msg_stats, rcpt, "none", &dsn);
    if (status == 0 && (request->flags & DEL_REQ_FLAG_SUCCESS))
        deliver_completed(src, rcpt->offset);
    result |= status;
    }

    /*
     * Clean up.
     */
    if (vstream_fclose(src))
    msg_warn("close %s %s: %m", request->queue_name, request->queue_id);

    return (result);
}

/* discard_service - perform service for client */

static void discard_service(VSTREAM *client_stream, char *unused_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
     * dedicated to the discard mailer. What we see below is a little
     * protocol to (1) tell the queue manager that we are ready, (2) read a
     * request from the queue manager, and (3) report the completion status
     * of that request. All connection-management stuff is handled by the
     * common code in single_server.c.
     */
    if ((request = deliver_request_read(client_stream)) != 0) {
    status = deliver_message(request);
    deliver_request_done(client_stream, request, status);
    }
}

/* pre_init - pre-jail initialization */

static void pre_init(char *unused_name, char **unused_argv)
{
    flush_init();
}

MAIL_VERSION_STAMP_DECLARE;

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

int     main(int argc, char **argv)
{

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

    single_server_main(argc, argv, discard_service,
               CA_MAIL_SERVER_PRE_INIT(pre_init),
               0);
}