Adding upstream version 3.5.24.upstream/3.5.24

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 736 insertions, 0 deletions

diff --git a/src/oqmgr/qmgr.c b/src/oqmgr/qmgr.c
new file mode 100644
index 0000000..02573f1
--- /dev/null
+++ b/src/oqmgr/qmgr.c
@@ -0,0 +1,736 @@
+/*++
+/* NAME
+/*	qmgr 8
+/* SUMMARY
+/*	old Postfix queue manager
+/* SYNOPSIS
+/*	\fBqmgr\fR [generic Postfix daemon options]
+/* DESCRIPTION
+/*	The \fBqmgr\fR(8) daemon awaits the arrival of incoming mail
+/*	and arranges for its delivery via Postfix delivery processes.
+/*	The actual mail routing strategy is delegated to the
+/*	\fBtrivial-rewrite\fR(8) daemon.
+/*	This program expects to be run from the \fBmaster\fR(8) process
+/*	manager.
+/*
+/*	Mail addressed to the local \fBdouble-bounce\fR address is
+/*	logged and discarded.  This stops potential loops caused by
+/*	undeliverable bounce notifications.
+/* MAIL QUEUES
+/* .ad
+/* .fi
+/*	The \fBqmgr\fR(8) daemon maintains the following queues:
+/* .IP \fBincoming\fR
+/*	Inbound mail from the network, or mail picked up by the
+/*	local \fBpickup\fR(8) agent from the \fBmaildrop\fR directory.
+/* .IP \fBactive\fR
+/*	Messages that the queue manager has opened for delivery. Only
+/*	a limited number of messages is allowed to enter the \fBactive\fR
+/*	queue (leaky bucket strategy, for a fixed delivery rate).
+/* .IP \fBdeferred\fR
+/*	Mail that could not be delivered upon the first attempt. The queue
+/*	manager implements exponential backoff by doubling the time between
+/*	delivery attempts.
+/* .IP \fBcorrupt\fR
+/*	Unreadable or damaged queue files are moved here for inspection.
+/* .IP \fBhold\fR
+/*	Messages that are kept "on hold" are kept here until someone
+/*	sets them free.
+/* DELIVERY STATUS REPORTS
+/* .ad
+/* .fi
+/*	The \fBqmgr\fR(8) daemon keeps an eye on per-message delivery status
+/*	reports in the following directories. Each status report file has
+/*	the same name as the corresponding message file:
+/* .IP \fBbounce\fR
+/*	Per-recipient status information about why mail is bounced.
+/*	These files are maintained by the \fBbounce\fR(8) daemon.
+/* .IP \fBdefer\fR
+/*	Per-recipient status information about why mail is delayed.
+/*	These files are maintained by the \fBdefer\fR(8) daemon.
+/* .IP \fBtrace\fR
+/*	Per-recipient status information as requested with the
+/*	Postfix "\fBsendmail -v\fR" or "\fBsendmail -bv\fR" command.
+/*	These files are maintained by the \fBtrace\fR(8) daemon.
+/* .PP
+/*	The \fBqmgr\fR(8) daemon is responsible for asking the
+/*	\fBbounce\fR(8), \fBdefer\fR(8) or \fBtrace\fR(8) daemons to
+/*	send delivery reports.
+/* STRATEGIES
+/* .ad
+/* .fi
+/*	The queue manager implements a variety of strategies for
+/*	either opening queue files (input) or for message delivery (output).
+/* .IP "\fBleaky bucket\fR"
+/*	This strategy limits the number of messages in the \fBactive\fR queue
+/*	and prevents the queue manager from running out of memory under
+/*	heavy load.
+/* .IP \fBfairness\fR
+/*	When the \fBactive\fR queue has room, the queue manager takes one
+/*	message from the \fBincoming\fR queue and one from the \fBdeferred\fR
+/*	queue. This prevents a large mail backlog from blocking the delivery
+/*	of new mail.
+/* .IP "\fBslow start\fR"
+/*	This strategy eliminates "thundering herd" problems by slowly
+/*	adjusting the number of parallel deliveries to the same destination.
+/* .IP "\fBround robin\fR"
+/*	The queue manager sorts delivery requests by destination.
+/*	Round-robin selection prevents one destination from dominating
+/*	deliveries to other destinations.
+/* .IP "\fBexponential backoff\fR"
+/*	Mail that cannot be delivered upon the first attempt is deferred.
+/*	The time interval between delivery attempts is doubled after each
+/*	attempt.
+/* .IP "\fBdestination status cache\fR"
+/*	The queue manager avoids unnecessary delivery attempts by
+/*	maintaining a short-term, in-memory list of unreachable destinations.
+/* TRIGGERS
+/* .ad
+/* .fi
+/*	On an idle system, the queue manager waits for the arrival of
+/*	trigger events, or it waits for a timer to go off. A trigger
+/*	is a one-byte message.
+/*	Depending on the message received, the queue manager performs
+/*	one of the following actions (the message is followed by the
+/*	symbolic constant used internally by the software):
+/* .IP "\fBD (QMGR_REQ_SCAN_DEFERRED)\fR"
+/*	Start a deferred queue scan.  If a deferred queue scan is already
+/*	in progress, that scan will be restarted as soon as it finishes.
+/* .IP "\fBI (QMGR_REQ_SCAN_INCOMING)\fR"
+/*	Start an incoming queue scan. If an incoming queue scan is already
+/*	in progress, that scan will be restarted as soon as it finishes.
+/* .IP "\fBA (QMGR_REQ_SCAN_ALL)\fR"
+/*	Ignore deferred queue file time stamps. The request affects
+/*	the next deferred queue scan.
+/* .IP "\fBF (QMGR_REQ_FLUSH_DEAD)\fR"
+/*	Purge all information about dead transports and destinations.
+/* .IP "\fBW (TRIGGER_REQ_WAKEUP)\fR"
+/*	Wakeup call, This is used by the master server to instantiate
+/*	servers that should not go away forever. The action is to start
+/*	an incoming queue scan.
+/* .PP
+/*	The \fBqmgr\fR(8) daemon reads an entire buffer worth of triggers.
+/*	Multiple identical trigger requests are collapsed into one, and
+/*	trigger requests are sorted so that \fBA\fR and \fBF\fR precede
+/*	\fBD\fR and \fBI\fR. Thus, in order to force a deferred queue run,
+/*	one would request \fBA F D\fR; in order to notify the queue manager
+/*	of the arrival of new mail one would request \fBI\fR.
+/* STANDARDS
+/*	RFC 3463 (Enhanced status codes)
+/*	RFC 3464 (Delivery status notifications)
+/* SECURITY
+/* .ad
+/* .fi
+/*	The \fBqmgr\fR(8) daemon is not security sensitive. It reads
+/*	single-character messages from untrusted local users, and thus may
+/*	be susceptible to denial of service attacks. The \fBqmgr\fR(8) daemon
+/*	does not talk to the outside world, and it can be run at fixed low
+/*	privilege in a chrooted environment.
+/* DIAGNOSTICS
+/*	Problems and transactions are logged to the \fBsyslogd\fR(8)
+/*	or \fBpostlogd\fR(8) daemon.
+/*	Corrupted message files are saved to the \fBcorrupt\fR queue
+/*	for further inspection.
+/*
+/*	Depending on the setting of the \fBnotify_classes\fR parameter,
+/*	the postmaster is notified of bounces and of other trouble.
+/* BUGS
+/*	A single queue manager process has to compete for disk access with
+/*	multiple front-end processes such as \fBcleanup\fR(8). A sudden burst of
+/*	inbound mail can negatively impact outbound delivery rates.
+/* CONFIGURATION PARAMETERS
+/* .ad
+/* .fi
+/*	Changes to \fBmain.cf\fR are not picked up automatically,
+/*	as \fBqmgr\fR(8)
+/*	is a persistent process. Use the command "\fBpostfix reload\fR" after
+/*	a configuration change.
+/*
+/*	The text below provides only a parameter summary. See
+/*	\fBpostconf\fR(5) for more details including examples.
+/*
+/*	In the text below, \fItransport\fR is the first field in a
+/*	\fBmaster.cf\fR entry.
+/* COMPATIBILITY CONTROLS
+/* .ad
+/* .fi
+/*	Available before Postfix version 2.5:
+/* .IP "\fBallow_min_user (no)\fR"
+/*	Allow a sender or recipient address to have `-' as the first
+/*	character.
+/* .PP
+/*	Available with Postfix version 2.7 and later:
+/* .IP "\fBdefault_filter_nexthop (empty)\fR"
+/*	When a content_filter or FILTER request specifies no explicit
+/*	next-hop destination, use $default_filter_nexthop instead; when
+/*	that value is empty, use the domain in the recipient address.
+/* ACTIVE QUEUE CONTROLS
+/* .ad
+/* .fi
+/* .IP "\fBqmgr_clog_warn_time (300s)\fR"
+/*	The minimal delay between warnings that a specific destination is
+/*	clogging up the Postfix active queue.
+/* .IP "\fBqmgr_message_active_limit (20000)\fR"
+/*	The maximal number of messages in the active queue.
+/* .IP "\fBqmgr_message_recipient_limit (20000)\fR"
+/*	The maximal number of recipients held in memory by the Postfix
+/*	queue manager, and the maximal size of the short-term,
+/*	in-memory "dead" destination status cache.
+/* DELIVERY CONCURRENCY CONTROLS
+/* .ad
+/* .fi
+/* .IP "\fBqmgr_fudge_factor (100)\fR"
+/*	Obsolete feature: the percentage of delivery resources that a busy
+/*	mail system will use up for delivery of a large mailing  list
+/*	message.
+/* .IP "\fBinitial_destination_concurrency (5)\fR"
+/*	The initial per-destination concurrency level for parallel delivery
+/*	to the same destination.
+/* .IP "\fBdefault_destination_concurrency_limit (20)\fR"
+/*	The default maximal number of parallel deliveries to the same
+/*	destination.
+/* .IP "\fBtransport_destination_concurrency_limit ($default_destination_concurrency_limit)\fR"
+/*	A transport-specific override for the
+/*	default_destination_concurrency_limit parameter value, where
+/*	\fItransport\fR is the master.cf name of the message delivery
+/*	transport.
+/* .PP
+/*	Available in Postfix version 2.5 and later:
+/* .IP "\fBtransport_initial_destination_concurrency ($initial_destination_concurrency)\fR"
+/*	A transport-specific override for the initial_destination_concurrency
+/*	parameter value, where \fItransport\fR is the master.cf name of
+/*	the message delivery transport.
+/* .IP "\fBdefault_destination_concurrency_failed_cohort_limit (1)\fR"
+/*	How many pseudo-cohorts must suffer connection or handshake
+/*	failure before a specific destination is considered unavailable
+/*	(and further delivery is suspended).
+/* .IP "\fBtransport_destination_concurrency_failed_cohort_limit ($default_destination_concurrency_failed_cohort_limit)\fR"
+/*	A transport-specific override for the
+/*	default_destination_concurrency_failed_cohort_limit parameter value,
+/*	where \fItransport\fR is the master.cf name of the message delivery
+/*	transport.
+/* .IP "\fBdefault_destination_concurrency_negative_feedback (1)\fR"
+/*	The per-destination amount of delivery concurrency negative
+/*	feedback, after a delivery completes with a connection or handshake
+/*	failure.
+/* .IP "\fBtransport_destination_concurrency_negative_feedback ($default_destination_concurrency_negative_feedback)\fR"
+/*	A transport-specific override for the
+/*	default_destination_concurrency_negative_feedback parameter value,
+/*	where \fItransport\fR is the master.cf name of the message delivery
+/*	transport.
+/* .IP "\fBdefault_destination_concurrency_positive_feedback (1)\fR"
+/*	The per-destination amount of delivery concurrency positive
+/*	feedback, after a delivery completes without connection or handshake
+/*	failure.
+/* .IP "\fBtransport_destination_concurrency_positive_feedback ($default_destination_concurrency_positive_feedback)\fR"
+/*	A transport-specific override for the
+/*	default_destination_concurrency_positive_feedback parameter value,
+/*	where \fItransport\fR is the master.cf name of the message delivery
+/*	transport.
+/* .IP "\fBdestination_concurrency_feedback_debug (no)\fR"
+/*	Make the queue manager's feedback algorithm verbose for performance
+/*	analysis purposes.
+/* RECIPIENT SCHEDULING CONTROLS
+/* .ad
+/* .fi
+/* .IP "\fBdefault_destination_recipient_limit (50)\fR"
+/*	The default maximal number of recipients per message delivery.
+/* .IP "\fBtransport_destination_recipient_limit ($default_destination_recipient_limit)\fR"
+/*	A transport-specific override for the
+/*	default_destination_recipient_limit parameter value, where
+/*	\fItransport\fR is the master.cf name of the message delivery
+/*	transport.
+/* OTHER RESOURCE AND RATE CONTROLS
+/* .ad
+/* .fi
+/* .IP "\fBminimal_backoff_time (300s)\fR"
+/*	The minimal time between attempts to deliver a deferred message;
+/*	prior to Postfix 2.4 the default value was 1000s.
+/* .IP "\fBmaximal_backoff_time (4000s)\fR"
+/*	The maximal time between attempts to deliver a deferred message.
+/* .IP "\fBmaximal_queue_lifetime (5d)\fR"
+/*	Consider a message as undeliverable, when delivery fails with a
+/*	temporary error, and the time in the queue has reached the
+/*	maximal_queue_lifetime limit.
+/* .IP "\fBqueue_run_delay (300s)\fR"
+/*	The time between deferred queue scans by the queue manager;
+/*	prior to Postfix 2.4 the default value was 1000s.
+/* .IP "\fBtransport_retry_time (60s)\fR"
+/*	The time between attempts by the Postfix queue manager to contact
+/*	a malfunctioning message delivery transport.
+/* .PP
+/*	Available in Postfix version 2.1 and later:
+/* .IP "\fBbounce_queue_lifetime (5d)\fR"
+/*	Consider a bounce message as undeliverable, when delivery fails
+/*	with a temporary error, and the time in the queue has reached the
+/*	bounce_queue_lifetime limit.
+/* .PP
+/*	Available in Postfix version 2.5 and later:
+/* .IP "\fBdefault_destination_rate_delay (0s)\fR"
+/*	The default amount of delay that is inserted between individual
+/*	message deliveries to the same destination and over the same message
+/*	delivery transport.
+/* .IP "\fBtransport_destination_rate_delay ($default_destination_rate_delay)\fR"
+/*	A transport-specific override for the default_destination_rate_delay
+/*	parameter value, where \fItransport\fR is the master.cf name of
+/*	the message delivery transport.
+/* .PP
+/*	Available in Postfix version 3.1 and later:
+/* .IP "\fBdefault_transport_rate_delay (0s)\fR"
+/*	The default amount of delay that is inserted between individual
+/*	message deliveries over the same message delivery transport,
+/*	regardless of destination.
+/* .IP "\fBtransport_transport_rate_delay ($default_transport_rate_delay)\fR"
+/*	A transport-specific override for the default_transport_rate_delay
+/*	parameter value, where the initial \fItransport\fR in the parameter
+/*	name is the master.cf name of the message delivery transport.
+/* SAFETY CONTROLS
+/* .ad
+/* .fi
+/* .IP "\fBqmgr_daemon_timeout (1000s)\fR"
+/*	How much time a Postfix queue manager process may take to handle
+/*	a request before it is terminated by a built-in watchdog timer.
+/* .IP "\fBqmgr_ipc_timeout (60s)\fR"
+/*	The time limit for the queue manager to send or receive information
+/*	over an internal communication channel.
+/* .PP
+/*	Available in Postfix version 3.1 and later:
+/* .IP "\fBaddress_verify_pending_request_limit (see 'postconf -d' output)\fR"
+/*	A safety limit that prevents address verification requests from
+/*	overwhelming the Postfix queue.
+/* 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 "\fBdefer_transports (empty)\fR"
+/*	The names of message delivery transports that should not deliver mail
+/*	unless someone issues "\fBsendmail -q\fR" or equivalent.
+/* .IP "\fBdelay_logging_resolution_limit (2)\fR"
+/*	The maximal number of digits after the decimal point when logging
+/*	sub-second delay values.
+/* .IP "\fBhelpful_warnings (yes)\fR"
+/*	Log warnings about problematic configuration settings, and provide
+/*	helpful suggestions.
+/* .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 version 3.0 and later:
+/* .IP "\fBconfirm_delay_cleared (no)\fR"
+/*	After sending a "your message is delayed" notification, inform
+/*	the sender when the delay clears up.
+/* .PP
+/*	Available in Postfix 3.3 and later:
+/* .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
+/*	/var/spool/postfix/incoming, incoming queue
+/*	/var/spool/postfix/active, active queue
+/*	/var/spool/postfix/deferred, deferred queue
+/*	/var/spool/postfix/bounce, non-delivery status
+/*	/var/spool/postfix/defer, non-delivery status
+/*	/var/spool/postfix/trace, delivery status
+/* SEE ALSO
+/*	trivial-rewrite(8), address routing
+/*	bounce(8), delivery status reports
+/*	postconf(5), configuration parameters
+/*	master(5), generic daemon options
+/*	master(8), process manager
+/*	postlogd(8), Postfix logging
+/*	syslogd(8), system logging
+/* README FILES
+/* .ad
+/* .fi
+/*	Use "\fBpostconf readme_directory\fR" or
+/*	"\fBpostconf html_directory\fR" to locate this information.
+/* .na
+/* .nf
+/*	QSHAPE_README, Postfix queue analysis
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* 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
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <ctype.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <events.h>
+#include <vstream.h>
+#include <dict.h>
+
+/* Global library. */
+
+#include <mail_queue.h>
+#include <recipient_list.h>
+#include <mail_conf.h>
+#include <mail_params.h>
+#include <mail_version.h>
+#include <mail_proto.h>			/* QMGR_SCAN constants */
+#include <mail_flow.h>
+#include <flush_clnt.h>
+
+/* Master process interface */
+
+#include <master_proto.h>
+#include <mail_server.h>
+
+/* Application-specific. */
+
+#include "qmgr.h"
+
+ /*
+  * Tunables.
+  */
+int     var_queue_run_delay;
+int     var_min_backoff_time;
+int     var_max_backoff_time;
+int     var_max_queue_time;
+int     var_dsn_queue_time;
+int     var_qmgr_active_limit;
+int     var_qmgr_rcpt_limit;
+int     var_init_dest_concurrency;
+int     var_transport_retry_time;
+int     var_dest_con_limit;
+int     var_dest_rcpt_limit;
+char   *var_defer_xports;
+int     var_qmgr_fudge;
+int     var_local_rcpt_lim;		/* XXX */
+int     var_local_con_lim;		/* XXX */
+bool    var_verp_bounce_off;
+int     var_qmgr_clog_warn_time;
+char   *var_conc_pos_feedback;
+char   *var_conc_neg_feedback;
+int     var_conc_cohort_limit;
+int     var_conc_feedback_debug;
+int     var_xport_rate_delay;
+int     var_dest_rate_delay;
+char   *var_def_filter_nexthop;
+int     var_qmgr_daemon_timeout;
+int     var_qmgr_ipc_timeout;
+int     var_dsn_delay_cleared;
+int     var_vrfy_pend_limit;
+
+static QMGR_SCAN *qmgr_scans[2];
+
+#define QMGR_SCAN_IDX_INCOMING 0
+#define QMGR_SCAN_IDX_DEFERRED 1
+#define QMGR_SCAN_IDX_COUNT (sizeof(qmgr_scans) / sizeof(qmgr_scans[0]))
+
+/* qmgr_deferred_run_event - queue manager heartbeat */
+
+static void qmgr_deferred_run_event(int unused_event, void *dummy)
+{
+
+    /*
+     * This routine runs when it is time for another deferred queue scan.
+     * Make sure this routine gets called again in the future.
+     */
+    qmgr_scan_request(qmgr_scans[QMGR_SCAN_IDX_DEFERRED], QMGR_SCAN_START);
+    event_request_timer(qmgr_deferred_run_event, dummy, var_queue_run_delay);
+}
+
+/* qmgr_trigger_event - respond to external trigger(s) */
+
+static void qmgr_trigger_event(char *buf, ssize_t len,
+			               char *unused_service, char **argv)
+{
+    int     incoming_flag = 0;
+    int     deferred_flag = 0;
+    int     i;
+
+    /*
+     * Sanity check. This service takes no command-line arguments.
+     */
+    if (argv[0])
+	msg_fatal("unexpected command-line argument: %s", argv[0]);
+
+    /*
+     * Collapse identical requests that have arrived since we looked last
+     * time. There is no client feedback so there is no need to process each
+     * request in order. And as long as we don't have conflicting requests we
+     * are free to sort them into the most suitable order.
+     */
+#define QMGR_FLUSH_BEFORE	(QMGR_FLUSH_ONCE | QMGR_FLUSH_DFXP)
+
+    for (i = 0; i < len; i++) {
+	if (msg_verbose)
+	    msg_info("request: %d (%c)",
+		     buf[i], ISALNUM(buf[i]) ? buf[i] : '?');
+	switch (buf[i]) {
+	case TRIGGER_REQ_WAKEUP:
+	case QMGR_REQ_SCAN_INCOMING:
+	    incoming_flag |= QMGR_SCAN_START;
+	    break;
+	case QMGR_REQ_SCAN_DEFERRED:
+	    deferred_flag |= QMGR_SCAN_START;
+	    break;
+	case QMGR_REQ_FLUSH_DEAD:
+	    deferred_flag |= QMGR_FLUSH_BEFORE;
+	    incoming_flag |= QMGR_FLUSH_BEFORE;
+	    break;
+	case QMGR_REQ_SCAN_ALL:
+	    deferred_flag |= QMGR_SCAN_ALL;
+	    incoming_flag |= QMGR_SCAN_ALL;
+	    break;
+	default:
+	    if (msg_verbose)
+		msg_info("request ignored");
+	    break;
+	}
+    }
+
+    /*
+     * Process each request type at most once. Modifiers take effect upon the
+     * next queue run. If no queue run is in progress, and a queue scan is
+     * requested, the request takes effect immediately.
+     */
+    if (incoming_flag != 0)
+	qmgr_scan_request(qmgr_scans[QMGR_SCAN_IDX_INCOMING], incoming_flag);
+    if (deferred_flag != 0)
+	qmgr_scan_request(qmgr_scans[QMGR_SCAN_IDX_DEFERRED], deferred_flag);
+}
+
+/* qmgr_loop - queue manager main loop */
+
+static int qmgr_loop(char *unused_name, char **unused_argv)
+{
+    char   *path;
+    ssize_t token_count;
+    int     feed = 0;
+    int     scan_idx;			/* Priority order scan index */
+    static int first_scan_idx = QMGR_SCAN_IDX_INCOMING;
+    int     last_scan_idx = QMGR_SCAN_IDX_COUNT - 1;
+    int     delay;
+
+    /*
+     * This routine runs as part of the event handling loop, after the event
+     * manager has delivered a timer or I/O event (including the completion
+     * of a connection to a delivery process), or after it has waited for a
+     * specified amount of time. The result value of qmgr_loop() specifies
+     * how long the event manager should wait for the next event.
+     */
+#define DONT_WAIT	0
+#define WAIT_FOR_EVENT	(-1)
+
+    /*
+     * Attempt to drain the active queue by allocating a suitable delivery
+     * process and by delivering mail via it. Delivery process allocation and
+     * mail delivery are asynchronous.
+     */
+    qmgr_active_drain();
+
+    /*
+     * Let some new blood into the active queue when the queue size is
+     * smaller than some configurable limit, and when the number of in-core
+     * recipients does not exceed some configurable limit.
+     * 
+     * We import one message per interrupt, to optimally tune the input count
+     * for the number of delivery agent protocol wait states, as explained in
+     * qmgr_transport.c.
+     */
+    delay = WAIT_FOR_EVENT;
+    for (scan_idx = 0; qmgr_message_count < var_qmgr_active_limit
+	 && qmgr_recipient_count < var_qmgr_rcpt_limit
+	 && scan_idx < QMGR_SCAN_IDX_COUNT; ++scan_idx) {
+	last_scan_idx = (scan_idx + first_scan_idx) % QMGR_SCAN_IDX_COUNT;
+	if ((path = qmgr_scan_next(qmgr_scans[last_scan_idx])) != 0) {
+	    delay = DONT_WAIT;
+	    if ((feed = qmgr_active_feed(qmgr_scans[last_scan_idx], path)) != 0)
+		break;
+	}
+    }
+
+    /*
+     * Round-robin the queue scans. When the active queue becomes full,
+     * prefer new mail over deferred mail.
+     */
+    if (qmgr_message_count < var_qmgr_active_limit
+	&& qmgr_recipient_count < var_qmgr_rcpt_limit) {
+	first_scan_idx = (last_scan_idx + 1) % QMGR_SCAN_IDX_COUNT;
+    } else if (first_scan_idx != QMGR_SCAN_IDX_INCOMING) {
+	first_scan_idx = QMGR_SCAN_IDX_INCOMING;
+    }
+
+    /*
+     * Global flow control. If enabled, slow down receiving processes that
+     * get ahead of the queue manager, but don't block them completely.
+     */
+    if (var_in_flow_delay > 0) {
+	token_count = mail_flow_count();
+	if (token_count < var_proc_limit) {
+	    if (feed != 0 && last_scan_idx == QMGR_SCAN_IDX_INCOMING)
+		mail_flow_put(1);
+	    else if (qmgr_scans[QMGR_SCAN_IDX_INCOMING]->handle == 0)
+		mail_flow_put(var_proc_limit - token_count);
+	} else if (token_count > var_proc_limit) {
+	    mail_flow_get(token_count - var_proc_limit);
+	}
+    }
+    return (delay);
+}
+
+/* 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);
+    }
+}
+
+/* qmgr_pre_init - pre-jail initialization */
+
+static void qmgr_pre_init(char *unused_name, char **unused_argv)
+{
+    flush_init();
+}
+
+/* qmgr_post_init - post-jail initialization */
+
+static void qmgr_post_init(char *unused_name, char **unused_argv)
+{
+
+    /*
+     * Sanity check.
+     */
+    if (var_qmgr_rcpt_limit < var_qmgr_active_limit) {
+	msg_warn("%s is smaller than %s - adjusting %s",
+	      VAR_QMGR_RCPT_LIMIT, VAR_QMGR_ACT_LIMIT, VAR_QMGR_RCPT_LIMIT);
+	var_qmgr_rcpt_limit = var_qmgr_active_limit;
+    }
+    if (var_dsn_queue_time > var_max_queue_time) {
+	msg_warn("%s is larger than %s - adjusting %s",
+		 VAR_DSN_QUEUE_TIME, VAR_MAX_QUEUE_TIME, VAR_DSN_QUEUE_TIME);
+	var_dsn_queue_time = var_max_queue_time;
+    }
+
+    /*
+     * This routine runs after the skeleton code has entered the chroot jail.
+     * Prevent automatic process suicide after a limited number of client
+     * requests or after a limited amount of idle time. Move any left-over
+     * entries from the active queue to the incoming queue, and give them a
+     * time stamp into the future, in order to allow ongoing deliveries to
+     * finish first. Start scanning the incoming and deferred queues.
+     * Left-over active queue entries are moved to the incoming queue because
+     * the incoming queue has priority; moving left-overs to the deferred
+     * queue could cause anomalous delays when "postfix reload/start" are
+     * issued often. Override the IPC timeout (default 3600s) so that the
+     * queue manager can reset a broken IPC channel before the watchdog timer
+     * goes off.
+     */
+    var_ipc_timeout = var_qmgr_ipc_timeout;
+    var_use_limit = 0;
+    var_idle_limit = 0;
+    qmgr_move(MAIL_QUEUE_ACTIVE, MAIL_QUEUE_INCOMING, event_time());
+    qmgr_scans[QMGR_SCAN_IDX_INCOMING] = qmgr_scan_create(MAIL_QUEUE_INCOMING);
+    qmgr_scans[QMGR_SCAN_IDX_DEFERRED] = qmgr_scan_create(MAIL_QUEUE_DEFERRED);
+    qmgr_scan_request(qmgr_scans[QMGR_SCAN_IDX_INCOMING], QMGR_SCAN_START);
+    qmgr_deferred_run_event(0, (void *) 0);
+}
+
+MAIL_VERSION_STAMP_DECLARE;
+
+/* main - the main program */
+
+int     main(int argc, char **argv)
+{
+    static const CONFIG_STR_TABLE str_table[] = {
+	VAR_DEFER_XPORTS, DEF_DEFER_XPORTS, &var_defer_xports, 0, 0,
+	VAR_CONC_POS_FDBACK, DEF_CONC_POS_FDBACK, &var_conc_pos_feedback, 1, 0,
+	VAR_CONC_NEG_FDBACK, DEF_CONC_NEG_FDBACK, &var_conc_neg_feedback, 1, 0,
+	VAR_DEF_FILTER_NEXTHOP, DEF_DEF_FILTER_NEXTHOP, &var_def_filter_nexthop, 0, 0,
+	0,
+    };
+    static const CONFIG_TIME_TABLE time_table[] = {
+	VAR_QUEUE_RUN_DELAY, DEF_QUEUE_RUN_DELAY, &var_queue_run_delay, 1, 0,
+	VAR_MIN_BACKOFF_TIME, DEF_MIN_BACKOFF_TIME, &var_min_backoff_time, 1, 0,
+	VAR_MAX_BACKOFF_TIME, DEF_MAX_BACKOFF_TIME, &var_max_backoff_time, 1, 0,
+	VAR_MAX_QUEUE_TIME, DEF_MAX_QUEUE_TIME, &var_max_queue_time, 0, 8640000,
+	VAR_DSN_QUEUE_TIME, DEF_DSN_QUEUE_TIME, &var_dsn_queue_time, 0, 8640000,
+	VAR_XPORT_RETRY_TIME, DEF_XPORT_RETRY_TIME, &var_transport_retry_time, 1, 0,
+	VAR_QMGR_CLOG_WARN_TIME, DEF_QMGR_CLOG_WARN_TIME, &var_qmgr_clog_warn_time, 0, 0,
+	VAR_XPORT_RATE_DELAY, DEF_XPORT_RATE_DELAY, &var_xport_rate_delay, 0, 0,
+	VAR_DEST_RATE_DELAY, DEF_DEST_RATE_DELAY, &var_dest_rate_delay, 0, 0,
+	VAR_QMGR_DAEMON_TIMEOUT, DEF_QMGR_DAEMON_TIMEOUT, &var_qmgr_daemon_timeout, 1, 0,
+	VAR_QMGR_IPC_TIMEOUT, DEF_QMGR_IPC_TIMEOUT, &var_qmgr_ipc_timeout, 1, 0,
+	0,
+    };
+    static const CONFIG_INT_TABLE int_table[] = {
+	VAR_QMGR_ACT_LIMIT, DEF_QMGR_ACT_LIMIT, &var_qmgr_active_limit, 1, 0,
+	VAR_QMGR_RCPT_LIMIT, DEF_QMGR_RCPT_LIMIT, &var_qmgr_rcpt_limit, 1, 0,
+	VAR_INIT_DEST_CON, DEF_INIT_DEST_CON, &var_init_dest_concurrency, 1, 0,
+	VAR_DEST_CON_LIMIT, DEF_DEST_CON_LIMIT, &var_dest_con_limit, 0, 0,
+	VAR_DEST_RCPT_LIMIT, DEF_DEST_RCPT_LIMIT, &var_dest_rcpt_limit, 0, 0,
+	VAR_QMGR_FUDGE, DEF_QMGR_FUDGE, &var_qmgr_fudge, 10, 100,
+	VAR_LOCAL_RCPT_LIMIT, DEF_LOCAL_RCPT_LIMIT, &var_local_rcpt_lim, 0, 0,
+	VAR_LOCAL_CON_LIMIT, DEF_LOCAL_CON_LIMIT, &var_local_con_lim, 0, 0,
+	VAR_CONC_COHORT_LIM, DEF_CONC_COHORT_LIM, &var_conc_cohort_limit, 0, 0,
+	VAR_VRFY_PEND_LIMIT, DEF_VRFY_PEND_LIMIT, &var_vrfy_pend_limit, 1, 0,
+	0,
+    };
+    static const CONFIG_BOOL_TABLE bool_table[] = {
+	VAR_VERP_BOUNCE_OFF, DEF_VERP_BOUNCE_OFF, &var_verp_bounce_off,
+	VAR_CONC_FDBACK_DEBUG, DEF_CONC_FDBACK_DEBUG, &var_conc_feedback_debug,
+	VAR_DSN_DELAY_CLEARED, DEF_DSN_DELAY_CLEARED, &var_dsn_delay_cleared,
+	0,
+    };
+
+    /*
+     * Fingerprint executables and core dumps.
+     */
+    MAIL_VERSION_STAMP_ALLOCATE;
+
+    /*
+     * Use the trigger service skeleton, because no-one else should be
+     * monitoring our service port while this process runs, and because we do
+     * not talk back to the client.
+     */
+    trigger_server_main(argc, argv, qmgr_trigger_event,
+			CA_MAIL_SERVER_INT_TABLE(int_table),
+			CA_MAIL_SERVER_STR_TABLE(str_table),
+			CA_MAIL_SERVER_BOOL_TABLE(bool_table),
+			CA_MAIL_SERVER_TIME_TABLE(time_table),
+			CA_MAIL_SERVER_PRE_INIT(qmgr_pre_init),
+			CA_MAIL_SERVER_POST_INIT(qmgr_post_init),
+			CA_MAIL_SERVER_LOOP(qmgr_loop),
+			CA_MAIL_SERVER_PRE_ACCEPT(pre_accept),
+			CA_MAIL_SERVER_SOLITARY,
+			CA_MAIL_SERVER_WATCHDOG(&var_qmgr_daemon_timeout),
+			0);
+}