1 files changed, 472 insertions, 0 deletions

diff --git a/src/oqmgr/qmgr_transport.c b/src/oqmgr/qmgr_transport.c
new file mode 100644
index 0000000..ed780db
--- /dev/null
+++ b/src/oqmgr/qmgr_transport.c
@@ -0,0 +1,472 @@
+/*++
+/* NAME
+/*	qmgr_transport 3
+/* SUMMARY
+/*	per-transport data structures
+/* SYNOPSIS
+/*	#include "qmgr.h"
+/*
+/*	QMGR_TRANSPORT *qmgr_transport_create(name)
+/*	const char *name;
+/*
+/*	QMGR_TRANSPORT *qmgr_transport_find(name)
+/*	const char *name;
+/*
+/*	QMGR_TRANSPORT *qmgr_transport_select()
+/*
+/*	void	qmgr_transport_alloc(transport, notify)
+/*	QMGR_TRANSPORT *transport;
+/*	void	(*notify)(QMGR_TRANSPORT *transport, VSTREAM *fp);
+/*
+/*	void	qmgr_transport_throttle(transport, dsn)
+/*	QMGR_TRANSPORT *transport;
+/*	DSN	*dsn;
+/*
+/*	void	qmgr_transport_unthrottle(transport)
+/*	QMGR_TRANSPORT *transport;
+/* DESCRIPTION
+/*	This module organizes the world by message transport type.
+/*	Each transport can have zero or more destination queues
+/*	associated with it.
+/*
+/*	qmgr_transport_create() instantiates a data structure for the
+/*	named transport type.
+/*
+/*	qmgr_transport_find() looks up an existing message transport
+/*	data structure.
+/*
+/*	qmgr_transport_select() attempts to find a transport that
+/*	has messages pending delivery.  This routine implements
+/*	round-robin search among transports.
+/*
+/*	qmgr_transport_alloc() allocates a delivery process for the
+/*	specified transport type. Allocation is performed asynchronously.
+/*	When a process becomes available, the application callback routine
+/*	is invoked with as arguments the transport and a stream that
+/*	is connected to a delivery process. It is an error to call
+/*	qmgr_transport_alloc() while delivery process allocation for
+/*	the same transport is in progress.
+/*
+/*	qmgr_transport_throttle blocks further allocation of delivery
+/*	processes for the named transport. Attempts to throttle a
+/*	throttled transport are ignored.
+/*
+/*	qmgr_transport_unthrottle() undoes qmgr_transport_throttle().
+/*	Attempts to unthrottle a non-throttled transport are ignored.
+/* DIAGNOSTICS
+/*	Panic: consistency check failure. Fatal: out of memory.
+/* 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 <unistd.h>
+
+#include <sys/time.h>			/* FD_SETSIZE */
+#include <sys/types.h>			/* FD_SETSIZE */
+#include <unistd.h>			/* FD_SETSIZE */
+
+#ifdef USE_SYS_SELECT_H
+#include <sys/select.h>			/* FD_SETSIZE */
+#endif
+
+/* Utility library. */
+
+#include <msg.h>
+#include <htable.h>
+#include <events.h>
+#include <mymalloc.h>
+#include <vstream.h>
+#include <iostuff.h>
+
+/* Global library. */
+
+#include <mail_proto.h>
+#include <recipient_list.h>
+#include <mail_conf.h>
+#include <mail_params.h>
+
+/* Application-specific. */
+
+#include "qmgr.h"
+
+HTABLE *qmgr_transport_byname;		/* transport by name */
+QMGR_TRANSPORT_LIST qmgr_transport_list;/* transports, round robin */
+
+ /*
+  * A local structure to remember a delivery process allocation request.
+  */
+typedef struct QMGR_TRANSPORT_ALLOC QMGR_TRANSPORT_ALLOC;
+
+struct QMGR_TRANSPORT_ALLOC {
+    QMGR_TRANSPORT *transport;		/* transport context */
+    VSTREAM *stream;			/* delivery service stream */
+    QMGR_TRANSPORT_ALLOC_NOTIFY notify;	/* application call-back routine */
+};
+
+ /*
+  * Connections to delivery agents are managed asynchronously. Each delivery
+  * agent connection goes through multiple wait states:
+  * 
+  * - With Linux/Solaris and old queue manager implementations only, wait for
+  * the server to invoke accept().
+  * 
+  * - Wait for the delivery agent's announcement that it is ready to receive a
+  * delivery request.
+  * 
+  * - Wait for the delivery request completion status.
+  * 
+  * Older queue manager implementations had only one pending delivery agent
+  * connection per transport. With low-latency destinations, the output rates
+  * were reduced on Linux/Solaris systems that had the extra wait state.
+  * 
+  * To maximize delivery agent output rates with low-latency destinations, the
+  * following changes were made to the queue manager by the end of the 2.4
+  * development cycle:
+  * 
+  * - The Linux/Solaris accept() wait state was eliminated.
+  * 
+  * - A pipeline was implemented for pending delivery agent connections. The
+  * number of pending delivery agent connections was increased from one to
+  * two: the number of before-delivery wait states, plus one extra pipeline
+  * slot to prevent the pipeline from stalling easily. Increasing the
+  * pipeline much further actually hurt performance.
+  * 
+  * - To reduce queue manager disk competition with delivery agents, the queue
+  * scanning algorithm was modified to import only one message per interrupt.
+  * The incoming and deferred queue scans now happen on alternate interrupts.
+  * 
+  * Simplistically reasoned, a non-zero (incoming + active) queue length is
+  * equivalent to a time shift for mail deliveries; this is undesirable when
+  * delivery agents are not fully utilized.
+  * 
+  * On the other hand a non-empty active queue is what allows us to do clever
+  * things such as queue file prefetch, concurrency windows, and connection
+  * caching; the idea is that such "thinking time" is affordable only after
+  * the output channels are maxed out.
+  */
+#ifndef QMGR_TRANSPORT_MAX_PEND
+#define QMGR_TRANSPORT_MAX_PEND	2
+#endif
+
+ /*
+  * Important note on the _transport_rate_delay implementation: after
+  * qmgr_transport_alloc() sets the QMGR_TRANSPORT_STAT_RATE_LOCK flag, all
+  * code paths must directly or indirectly invoke qmgr_transport_unthrottle()
+  * or qmgr_transport_throttle(). Otherwise, transports with non-zero
+  * _transport_rate_delay will become stuck.
+  */
+
+/* qmgr_transport_unthrottle_wrapper - in case (char *) != (struct *) */
+
+static void qmgr_transport_unthrottle_wrapper(int unused_event, void *context)
+{
+    qmgr_transport_unthrottle((QMGR_TRANSPORT *) context);
+}
+
+/* qmgr_transport_unthrottle - open the throttle */
+
+void    qmgr_transport_unthrottle(QMGR_TRANSPORT *transport)
+{
+    const char *myname = "qmgr_transport_unthrottle";
+
+    /*
+     * This routine runs after expiration of the timer set by
+     * qmgr_transport_throttle(), or whenever a delivery transport has been
+     * used without malfunction. In either case, we enable delivery again if
+     * the transport was throttled. We always reset the transport rate lock.
+     */
+    if ((transport->flags & QMGR_TRANSPORT_STAT_DEAD) != 0) {
+	if (msg_verbose)
+	    msg_info("%s: transport %s", myname, transport->name);
+	transport->flags &= ~QMGR_TRANSPORT_STAT_DEAD;
+	if (transport->dsn == 0)
+	    msg_panic("%s: transport %s: null reason",
+		      myname, transport->name);
+	dsn_free(transport->dsn);
+	transport->dsn = 0;
+	event_cancel_timer(qmgr_transport_unthrottle_wrapper,
+			   (void *) transport);
+    }
+    if (transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK)
+	transport->flags &= ~QMGR_TRANSPORT_STAT_RATE_LOCK;
+}
+
+/* qmgr_transport_throttle - disable delivery process allocation */
+
+void    qmgr_transport_throttle(QMGR_TRANSPORT *transport, DSN *dsn)
+{
+    const char *myname = "qmgr_transport_throttle";
+
+    /*
+     * We are unable to connect to a deliver process for this type of message
+     * transport. Instead of hosing the system by retrying in a tight loop,
+     * back off and disable this transport type for a while.
+     */
+    if ((transport->flags & QMGR_TRANSPORT_STAT_DEAD) == 0) {
+	if (msg_verbose)
+	    msg_info("%s: transport %s: status: %s reason: %s",
+		     myname, transport->name, dsn->status, dsn->reason);
+	transport->flags |= QMGR_TRANSPORT_STAT_DEAD;
+	if (transport->dsn)
+	    msg_panic("%s: transport %s: spurious reason: %s",
+		      myname, transport->name, transport->dsn->reason);
+	transport->dsn = DSN_COPY(dsn);
+	event_request_timer(qmgr_transport_unthrottle_wrapper,
+			    (void *) transport, var_transport_retry_time);
+    }
+}
+
+/* qmgr_transport_abort - transport connect watchdog */
+
+static void qmgr_transport_abort(int unused_event, void *context)
+{
+    QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context;
+
+    msg_fatal("timeout connecting to transport: %s", alloc->transport->name);
+}
+
+/* qmgr_transport_rate_event - delivery process availability notice */
+
+static void qmgr_transport_rate_event(int unused_event, void *context)
+{
+    QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context;
+
+    alloc->notify(alloc->transport, alloc->stream);
+    myfree((void *) alloc);
+}
+
+/* qmgr_transport_event - delivery process availability notice */
+
+static void qmgr_transport_event(int unused_event, void *context)
+{
+    QMGR_TRANSPORT_ALLOC *alloc = (QMGR_TRANSPORT_ALLOC *) context;
+
+    /*
+     * This routine notifies the application when the request given to
+     * qmgr_transport_alloc() completes.
+     */
+    if (msg_verbose)
+	msg_info("transport_event: %s", alloc->transport->name);
+
+    /*
+     * Connection request completed. Stop the watchdog timer.
+     */
+    event_cancel_timer(qmgr_transport_abort, context);
+
+    /*
+     * Disable further read events that end up calling this function, and
+     * free up this pending connection pipeline slot.
+     */
+    if (alloc->stream) {
+	event_disable_readwrite(vstream_fileno(alloc->stream));
+	non_blocking(vstream_fileno(alloc->stream), BLOCKING);
+    }
+    alloc->transport->pending -= 1;
+
+    /*
+     * Notify the requestor.
+     */
+    if (alloc->transport->xport_rate_delay > 0) {
+	if ((alloc->transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK) == 0)
+	    msg_panic("transport_event: missing rate lock for transport %s",
+		      alloc->transport->name);
+	event_request_timer(qmgr_transport_rate_event, (void *) alloc,
+			    alloc->transport->xport_rate_delay);
+    } else {
+	alloc->notify(alloc->transport, alloc->stream);
+	myfree((void *) alloc);
+    }
+}
+
+/* qmgr_transport_select - select transport for allocation */
+
+QMGR_TRANSPORT *qmgr_transport_select(void)
+{
+    QMGR_TRANSPORT *xport;
+    QMGR_QUEUE *queue;
+    int     need;
+
+    /*
+     * If we find a suitable transport, rotate the list of transports to
+     * effectuate round-robin selection. See similar selection code in
+     * qmgr_queue_select().
+     * 
+     * This function is called repeatedly until all transports have maxed out
+     * the number of pending delivery agent connections, until all delivery
+     * agent concurrency windows are maxed out, or until we run out of "todo"
+     * queue entries.
+     */
+#define MIN5af51743e4eef(x, y) ((x) < (y) ? (x) : (y))
+
+    for (xport = qmgr_transport_list.next; xport; xport = xport->peers.next) {
+	if ((xport->flags & QMGR_TRANSPORT_STAT_DEAD) != 0
+	    || (xport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK) != 0
+	    || xport->pending >= QMGR_TRANSPORT_MAX_PEND)
+	    continue;
+	need = xport->pending + 1;
+	for (queue = xport->queue_list.next; queue; queue = queue->peers.next) {
+	    if (QMGR_QUEUE_READY(queue) == 0)
+		continue;
+	    if ((need -= MIN5af51743e4eef(queue->window - queue->busy_refcount,
+					  queue->todo_refcount)) <= 0) {
+		QMGR_LIST_ROTATE(qmgr_transport_list, xport);
+		if (msg_verbose)
+		    msg_info("qmgr_transport_select: %s", xport->name);
+		return (xport);
+	    }
+	}
+    }
+    return (0);
+}
+
+/* qmgr_transport_alloc - allocate delivery process */
+
+void    qmgr_transport_alloc(QMGR_TRANSPORT *transport, QMGR_TRANSPORT_ALLOC_NOTIFY notify)
+{
+    QMGR_TRANSPORT_ALLOC *alloc;
+
+    /*
+     * Sanity checks.
+     */
+    if (transport->flags & QMGR_TRANSPORT_STAT_DEAD)
+	msg_panic("qmgr_transport: dead transport: %s", transport->name);
+    if (transport->flags & QMGR_TRANSPORT_STAT_RATE_LOCK)
+	msg_panic("qmgr_transport: rate-locked transport: %s", transport->name);
+    if (transport->pending >= QMGR_TRANSPORT_MAX_PEND)
+	msg_panic("qmgr_transport: excess allocation: %s", transport->name);
+
+    /*
+     * When this message delivery transport is rate-limited, do not select it
+     * again before the end of a message delivery transaction.
+     */
+    if (transport->xport_rate_delay > 0)
+	transport->flags |= QMGR_TRANSPORT_STAT_RATE_LOCK;
+
+    /*
+     * Connect to the well-known port for this delivery service, and wake up
+     * when a process announces its availability. Allow only a limited number
+     * of delivery process allocation attempts for this transport. In case of
+     * problems, back off. Do not hose the system when it is in trouble
+     * already.
+     * 
+     * Use non-blocking connect(), so that Linux won't block the queue manager
+     * until the delivery agent calls accept().
+     * 
+     * When the connection to delivery agent cannot be completed, notify the
+     * event handler so that it can throttle the transport and defer the todo
+     * queues, just like it does when communication fails *after* connection
+     * completion.
+     * 
+     * Before Postfix 2.4, the event handler was not invoked after connect()
+     * error, and mail was not deferred. Because of this, mail would be stuck
+     * in the active queue after triggering a "connection refused" condition.
+     */
+    alloc = (QMGR_TRANSPORT_ALLOC *) mymalloc(sizeof(*alloc));
+    alloc->transport = transport;
+    alloc->notify = notify;
+    transport->pending += 1;
+    if ((alloc->stream = mail_connect(MAIL_CLASS_PRIVATE, transport->name,
+				      NON_BLOCKING)) == 0) {
+	msg_warn("connect to transport %s/%s: %m",
+		 MAIL_CLASS_PRIVATE, transport->name);
+	event_request_timer(qmgr_transport_event, (void *) alloc, 0);
+	return;
+    }
+#if (EVENTS_STYLE != EVENTS_STYLE_SELECT) && defined(CA_VSTREAM_CTL_DUPFD)
+#ifndef THRESHOLD_FD_WORKAROUND
+#define THRESHOLD_FD_WORKAROUND 128
+#endif
+    vstream_control(alloc->stream,
+		    CA_VSTREAM_CTL_DUPFD(THRESHOLD_FD_WORKAROUND),
+		    CA_VSTREAM_CTL_END);
+#endif
+    event_enable_read(vstream_fileno(alloc->stream), qmgr_transport_event,
+		      (void *) alloc);
+
+    /*
+     * Guard against broken systems.
+     */
+    event_request_timer(qmgr_transport_abort, (void *) alloc,
+			var_daemon_timeout);
+}
+
+/* qmgr_transport_create - create transport instance */
+
+QMGR_TRANSPORT *qmgr_transport_create(const char *name)
+{
+    QMGR_TRANSPORT *transport;
+
+    if (htable_find(qmgr_transport_byname, name) != 0)
+	msg_panic("qmgr_transport_create: transport exists: %s", name);
+    transport = (QMGR_TRANSPORT *) mymalloc(sizeof(QMGR_TRANSPORT));
+    transport->flags = 0;
+    transport->pending = 0;
+    transport->name = mystrdup(name);
+
+    /*
+     * Use global configuration settings or transport-specific settings.
+     */
+    transport->dest_concurrency_limit =
+	get_mail_conf_int2(name, _DEST_CON_LIMIT,
+			   var_dest_con_limit, 0, 0);
+    transport->recipient_limit =
+	get_mail_conf_int2(name, _DEST_RCPT_LIMIT,
+			   var_dest_rcpt_limit, 0, 0);
+    transport->init_dest_concurrency =
+	get_mail_conf_int2(name, _INIT_DEST_CON,
+			   var_init_dest_concurrency, 1, 0);
+    transport->xport_rate_delay = get_mail_conf_time2(name, _XPORT_RATE_DELAY,
+						      var_xport_rate_delay,
+						      's', 0, 0);
+    transport->rate_delay = get_mail_conf_time2(name, _DEST_RATE_DELAY,
+						var_dest_rate_delay,
+						's', 0, 0);
+
+    if (transport->rate_delay > 0)
+	transport->dest_concurrency_limit = 1;
+    if (transport->dest_concurrency_limit != 0
+    && transport->dest_concurrency_limit < transport->init_dest_concurrency)
+	transport->init_dest_concurrency = transport->dest_concurrency_limit;
+
+    transport->queue_byname = htable_create(0);
+    QMGR_LIST_INIT(transport->queue_list);
+    transport->dsn = 0;
+    qmgr_feedback_init(&transport->pos_feedback, name, _CONC_POS_FDBACK,
+		       VAR_CONC_POS_FDBACK, var_conc_pos_feedback);
+    qmgr_feedback_init(&transport->neg_feedback, name, _CONC_NEG_FDBACK,
+		       VAR_CONC_NEG_FDBACK, var_conc_neg_feedback);
+    transport->fail_cohort_limit =
+	get_mail_conf_int2(name, _CONC_COHORT_LIM,
+			   var_conc_cohort_limit, 0, 0);
+    if (qmgr_transport_byname == 0)
+	qmgr_transport_byname = htable_create(10);
+    htable_enter(qmgr_transport_byname, name, (void *) transport);
+    QMGR_LIST_APPEND(qmgr_transport_list, transport);
+    if (msg_verbose)
+	msg_info("qmgr_transport_create: %s concurrency %d recipients %d",
+		 transport->name, transport->dest_concurrency_limit,
+		 transport->recipient_limit);
+    return (transport);
+}
+
+/* qmgr_transport_find - find transport instance */
+
+QMGR_TRANSPORT *qmgr_transport_find(const char *name)
+{
+    return ((QMGR_TRANSPORT *) htable_find(qmgr_transport_byname, name));
+}