/*	$NetBSD: qmgr_deliver.c,v 1.2 2017/02/14 01:16:46 christos Exp $	*/

/*++
/* NAME
/*	qmgr_deliver 3
/* SUMMARY
/*	deliver one per-site queue entry to that site
/* SYNOPSIS
/*	#include "qmgr.h"
/*
/*	int	qmgr_deliver_concurrency;
/*
/*	int	qmgr_deliver(transport, fp)
/*	QMGR_TRANSPORT *transport;
/*	VSTREAM	*fp;
/* DESCRIPTION
/*	This module implements the client side of the `queue manager
/*	to delivery agent' protocol. The queue manager uses
/*	asynchronous I/O so that it can drive multiple delivery
/*	agents in parallel. Depending on the outcome of a delivery
/*	attempt, the status of messages, queues and transports is
/*	updated.
/*
/*	qmgr_deliver_concurrency is a global counter that says how
/*	many delivery processes are in use. This can be used, for
/*	example, to control the size of the `active' message queue.
/*
/*	qmgr_deliver() executes when a delivery process announces its
/*	availability for the named transport. It arranges for delivery
/*	of a suitable queue entry.  The \fIfp\fR argument specifies a
/*	stream that is connected to the delivery process, or a null
/*	pointer if the transport accepts no connection. Upon completion
/*	of delivery (successful or not), the stream is closed, so that the
/*	delivery process is released.
/* DIAGNOSTICS
/* 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 <time.h>
#include <string.h>

/* Utility library. */

#include <msg.h>
#include <vstring.h>
#include <vstream.h>
#include <vstring_vstream.h>
#include <events.h>
#include <iostuff.h>
#include <stringops.h>
#include <mymalloc.h>

/* Global library. */

#include <mail_queue.h>
#include <mail_proto.h>
#include <recipient_list.h>
#include <mail_params.h>
#include <deliver_request.h>
#include <verp_sender.h>
#include <dsn_util.h>
#include <dsn_buf.h>
#include <dsb_scan.h>
#include <rcpt_print.h>
#include <smtputf8.h>

/* Application-specific. */

#include "qmgr.h"

 /*
  * 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.
  */

int     qmgr_deliver_concurrency;

 /*
  * Message delivery status codes.
  */
#define DELIVER_STAT_OK		0	/* all recipients delivered */
#define DELIVER_STAT_DEFER	1	/* try some recipients later */
#define DELIVER_STAT_CRASH	2	/* mailer internal problem */

/* qmgr_deliver_initial_reply - retrieve initial delivery process response */

static int qmgr_deliver_initial_reply(VSTREAM *stream)
{
    int     stat;

    if (peekfd(vstream_fileno(stream)) < 0) {
	msg_warn("%s: premature disconnect", VSTREAM_PATH(stream));
	return (DELIVER_STAT_CRASH);
    } else if (attr_scan(stream, ATTR_FLAG_STRICT,
			 RECV_ATTR_INT(MAIL_ATTR_STATUS, &stat),
			 ATTR_TYPE_END) != 1) {
	msg_warn("%s: malformed response", VSTREAM_PATH(stream));
	return (DELIVER_STAT_CRASH);
    } else {
	return (stat ? DELIVER_STAT_DEFER : 0);
    }
}

/* qmgr_deliver_final_reply - retrieve final delivery process response */

static int qmgr_deliver_final_reply(VSTREAM *stream, DSN_BUF *dsb)
{
    int     stat;

    if (peekfd(vstream_fileno(stream)) < 0) {
	msg_warn("%s: premature disconnect", VSTREAM_PATH(stream));
	return (DELIVER_STAT_CRASH);
    } else if (attr_scan(stream, ATTR_FLAG_STRICT,
			 RECV_ATTR_FUNC(dsb_scan, (void *) dsb),
			 RECV_ATTR_INT(MAIL_ATTR_STATUS, &stat),
			 ATTR_TYPE_END) != 2) {
	msg_warn("%s: malformed response", VSTREAM_PATH(stream));
	return (DELIVER_STAT_CRASH);
    } else {
	return (stat ? DELIVER_STAT_DEFER : 0);
    }
}

/* qmgr_deliver_send_request - send delivery request to delivery process */

static int qmgr_deliver_send_request(QMGR_ENTRY *entry, VSTREAM *stream)
{
    RECIPIENT_LIST list = entry->rcpt_list;
    RECIPIENT *recipient;
    QMGR_MESSAGE *message = entry->message;
    VSTRING *sender_buf = 0;
    MSG_STATS stats;
    char   *sender;
    int     flags;
    int     smtputf8 = message->smtputf8;
    const char *addr;

    /*
     * Todo: integrate with code up-stream that builds the delivery request.
     */
    for (recipient = list.info; recipient < list.info + list.len; recipient++)
	if (var_smtputf8_enable && (addr = recipient->address)[0]
	    && !allascii(addr) && valid_utf8_string(addr, strlen(addr))) {
	    smtputf8 |= SMTPUTF8_FLAG_RECIPIENT;
	    if (message->verp_delims)
		smtputf8 |= SMTPUTF8_FLAG_SENDER;
	}

    /*
     * If variable envelope return path is requested, change prefix+@origin
     * into prefix+user=domain@origin. Note that with VERP there is only one
     * recipient per delivery.
     */
    if (message->verp_delims == 0) {
	sender = message->sender;
    } else {
	sender_buf = vstring_alloc(100);
	verp_sender(sender_buf, message->verp_delims,
		    message->sender, list.info);
	sender = vstring_str(sender_buf);
    }

    flags = message->tflags
	| entry->queue->dflags
	| (message->inspect_xport ? DEL_REQ_FLAG_BOUNCE : DEL_REQ_FLAG_DEFLT);
    (void) QMGR_MSG_STATS(&stats, message);
    attr_print(stream, ATTR_FLAG_NONE,
	       SEND_ATTR_INT(MAIL_ATTR_FLAGS, flags),
	       SEND_ATTR_STR(MAIL_ATTR_QUEUE, message->queue_name),
	       SEND_ATTR_STR(MAIL_ATTR_QUEUEID, message->queue_id),
	       SEND_ATTR_LONG(MAIL_ATTR_OFFSET, message->data_offset),
	       SEND_ATTR_LONG(MAIL_ATTR_SIZE, message->cont_length),
	       SEND_ATTR_STR(MAIL_ATTR_NEXTHOP, entry->queue->nexthop),
	       SEND_ATTR_STR(MAIL_ATTR_ENCODING, message->encoding),
	       SEND_ATTR_INT(MAIL_ATTR_SMTPUTF8, smtputf8),
	       SEND_ATTR_STR(MAIL_ATTR_SENDER, sender),
	       SEND_ATTR_STR(MAIL_ATTR_DSN_ENVID, message->dsn_envid),
	       SEND_ATTR_INT(MAIL_ATTR_DSN_RET, message->dsn_ret),
	       SEND_ATTR_FUNC(msg_stats_print, (void *) &stats),
    /* XXX Should be encapsulated with ATTR_TYPE_FUNC. */
	     SEND_ATTR_STR(MAIL_ATTR_LOG_CLIENT_NAME, message->client_name),
	     SEND_ATTR_STR(MAIL_ATTR_LOG_CLIENT_ADDR, message->client_addr),
	     SEND_ATTR_STR(MAIL_ATTR_LOG_CLIENT_PORT, message->client_port),
	     SEND_ATTR_STR(MAIL_ATTR_LOG_PROTO_NAME, message->client_proto),
	       SEND_ATTR_STR(MAIL_ATTR_LOG_HELO_NAME, message->client_helo),
    /* XXX Should be encapsulated with ATTR_TYPE_FUNC. */
	       SEND_ATTR_STR(MAIL_ATTR_SASL_METHOD, message->sasl_method),
	     SEND_ATTR_STR(MAIL_ATTR_SASL_USERNAME, message->sasl_username),
	       SEND_ATTR_STR(MAIL_ATTR_SASL_SENDER, message->sasl_sender),
    /* XXX Ditto if we want to pass TLS certificate info. */
	       SEND_ATTR_STR(MAIL_ATTR_LOG_IDENT, message->log_ident),
	     SEND_ATTR_STR(MAIL_ATTR_RWR_CONTEXT, message->rewrite_context),
	       SEND_ATTR_INT(MAIL_ATTR_RCPT_COUNT, list.len),
	       ATTR_TYPE_END);
    if (sender_buf != 0)
	vstring_free(sender_buf);
    for (recipient = list.info; recipient < list.info + list.len; recipient++)
	attr_print(stream, ATTR_FLAG_NONE,
		   SEND_ATTR_FUNC(rcpt_print, (void *) recipient),
		   ATTR_TYPE_END);
    if (vstream_fflush(stream) != 0) {
	msg_warn("write to process (%s): %m", entry->queue->transport->name);
	return (-1);
    } else {
	if (msg_verbose)
	    msg_info("qmgr_deliver: site `%s'", entry->queue->name);
	return (0);
    }
}

/* qmgr_deliver_abort - transport response watchdog */

static void qmgr_deliver_abort(int unused_event, void *context)
{
    QMGR_ENTRY *entry = (QMGR_ENTRY *) context;
    QMGR_QUEUE *queue = entry->queue;
    QMGR_TRANSPORT *transport = queue->transport;
    QMGR_MESSAGE *message = entry->message;

    msg_fatal("%s: timeout receiving delivery status from transport: %s",
	      message->queue_id, transport->name);
}

/* qmgr_deliver_update - process delivery status report */

static void qmgr_deliver_update(int unused_event, void *context)
{
    QMGR_ENTRY *entry = (QMGR_ENTRY *) context;
    QMGR_QUEUE *queue = entry->queue;
    QMGR_TRANSPORT *transport = queue->transport;
    QMGR_MESSAGE *message = entry->message;
    static DSN_BUF *dsb;
    int     status;

    /*
     * Release the delivery agent from a "hot" queue entry.
     */
#define QMGR_DELIVER_RELEASE_AGENT(entry) do { \
	event_disable_readwrite(vstream_fileno(entry->stream)); \
	(void) vstream_fclose(entry->stream); \
	entry->stream = 0; \
	qmgr_deliver_concurrency--; \
    } while (0)

    if (dsb == 0)
	dsb = dsb_create();

    /*
     * The message transport has responded. Stop the watchdog timer.
     */
    event_cancel_timer(qmgr_deliver_abort, context);

    /*
     * Retrieve the delivery agent status report. The numerical status code
     * indicates if delivery should be tried again. The reason text is sent
     * only when a site should be avoided for a while, so that the queue
     * manager can log why it does not even try to schedule delivery to the
     * affected recipients.
     */
    status = qmgr_deliver_final_reply(entry->stream, dsb);

    /*
     * The mail delivery process failed for some reason (although delivery
     * may have been successful). Back off with this transport type for a
     * while. Dispose of queue entries for this transport that await
     * selection (the todo lists). Stay away from queue entries that have
     * been selected (the busy lists), or we would have dangling pointers.
     * The queue itself won't go away before we dispose of the current queue
     * entry.
     */
    if (status == DELIVER_STAT_CRASH) {
	message->flags |= DELIVER_STAT_DEFER;
#if 0
	whatsup = concatenate("unknown ", transport->name,
			      " mail transport error", (char *) 0);
	qmgr_transport_throttle(transport,
				DSN_SIMPLE(&dsb->dsn, "4.3.0", whatsup));
	myfree(whatsup);
#else
	qmgr_transport_throttle(transport,
				DSN_SIMPLE(&dsb->dsn, "4.3.0",
					   "unknown mail transport error"));
#endif
	msg_warn("transport %s failure -- see a previous warning/fatal/panic logfile record for the problem description",
		 transport->name);

	/*
	 * Assume the worst and write a defer logfile record for each
	 * recipient. This omission was already present in the first queue
	 * manager implementation of 199703, and was fixed 200511.
	 * 
	 * To avoid the synchronous qmgr_defer_recipient() operation for each
	 * recipient of this queue entry, release the delivery process and
	 * move the entry back to the todo queue. Let qmgr_defer_transport()
	 * log the recipient asynchronously if possible, and get out of here.
	 * Note: if asynchronous logging is not possible,
	 * qmgr_defer_transport() eventually invokes qmgr_entry_done() and
	 * the entry becomes a dangling pointer.
	 */
	QMGR_DELIVER_RELEASE_AGENT(entry);
	qmgr_entry_unselect(queue, entry);
	qmgr_defer_transport(transport, &dsb->dsn);
	return;
    }

    /*
     * This message must be tried again.
     * 
     * If we have a problem talking to this site, back off with this site for a
     * while; dispose of queue entries for this site that await selection
     * (the todo list); stay away from queue entries that have been selected
     * (the busy list), or we would have dangling pointers. The queue itself
     * won't go away before we dispose of the current queue entry.
     * 
     * XXX Caution: DSN_COPY() will panic on empty status or reason.
     */
#define SUSPENDED	"delivery temporarily suspended: "

    if (status == DELIVER_STAT_DEFER) {
	message->flags |= DELIVER_STAT_DEFER;
	if (VSTRING_LEN(dsb->status)) {
	    /* Sanitize the DSN status/reason from the delivery agent. */
	    if (!dsn_valid(vstring_str(dsb->status)))
		vstring_strcpy(dsb->status, "4.0.0");
	    if (VSTRING_LEN(dsb->reason) == 0)
		vstring_strcpy(dsb->reason, "unknown error");
	    vstring_prepend(dsb->reason, SUSPENDED, sizeof(SUSPENDED) - 1);
	    if (QMGR_QUEUE_READY(queue)) {
		qmgr_queue_throttle(queue, DSN_FROM_DSN_BUF(dsb));
		if (QMGR_QUEUE_THROTTLED(queue))
		    qmgr_defer_todo(queue, &dsb->dsn);
	    }
	}
    }

    /*
     * No problems detected. Mark the transport and queue as alive. The queue
     * itself won't go away before we dispose of the current queue entry.
     */
    if (status != DELIVER_STAT_CRASH) {
	qmgr_transport_unthrottle(transport);
	if (VSTRING_LEN(dsb->reason) == 0)
	    qmgr_queue_unthrottle(queue);
    }

    /*
     * Release the delivery process, and give some other queue entry a chance
     * to be delivered. When all recipients for a message have been tried,
     * decide what to do next with this message: defer, bounce, delete.
     */
    QMGR_DELIVER_RELEASE_AGENT(entry);
    qmgr_entry_done(entry, QMGR_QUEUE_BUSY);
}

/* qmgr_deliver - deliver one per-site queue entry */

void    qmgr_deliver(QMGR_TRANSPORT *transport, VSTREAM *stream)
{
    QMGR_QUEUE *queue;
    QMGR_ENTRY *entry;
    DSN     dsn;

    /*
     * Find out if this delivery process is really available. Once elected,
     * the delivery process is supposed to express its happiness. If there is
     * a problem, wipe the pending deliveries for this transport. This
     * routine runs in response to an external event, so it does not run
     * while some other queue manipulation is happening.
     */
    if (stream == 0 || qmgr_deliver_initial_reply(stream) != 0) {
#if 0
	whatsup = concatenate(transport->name,
			      " mail transport unavailable", (char *) 0);
	qmgr_transport_throttle(transport,
				DSN_SIMPLE(&dsn, "4.3.0", whatsup));
	myfree(whatsup);
#else
	qmgr_transport_throttle(transport,
				DSN_SIMPLE(&dsn, "4.3.0",
					   "mail transport unavailable"));
#endif
	qmgr_defer_transport(transport, &dsn);
	if (stream)
	    (void) vstream_fclose(stream);
	return;
    }

    /*
     * Find a suitable queue entry. Things may have changed since this
     * transport was allocated. If no suitable entry is found,
     * unceremoniously disconnect from the delivery process. The delivery
     * agent request reading routine is prepared for the queue manager to
     * change its mind for no apparent reason.
     */
    if ((queue = qmgr_queue_select(transport)) == 0
	|| (entry = qmgr_entry_select(queue)) == 0) {
	(void) vstream_fclose(stream);
	return;
    }

    /*
     * Send the queue file info and recipient info to the delivery process.
     * If there is a problem, wipe the pending deliveries for this transport.
     * This routine runs in response to an external event, so it does not run
     * while some other queue manipulation is happening.
     */
    if (qmgr_deliver_send_request(entry, stream) < 0) {
	qmgr_entry_unselect(queue, entry);
#if 0
	whatsup = concatenate(transport->name,
			      " mail transport unavailable", (char *) 0);
	qmgr_transport_throttle(transport,
				DSN_SIMPLE(&dsn, "4.3.0", whatsup));
	myfree(whatsup);
#else
	qmgr_transport_throttle(transport,
				DSN_SIMPLE(&dsn, "4.3.0",
					   "mail transport unavailable"));
#endif
	qmgr_defer_transport(transport, &dsn);
	/* warning: entry and queue may be dangling pointers here */
	(void) vstream_fclose(stream);
	return;
    }

    /*
     * If we get this far, go wait for the delivery status report.
     */
    qmgr_deliver_concurrency++;
    entry->stream = stream;
    event_enable_read(vstream_fileno(stream),
		      qmgr_deliver_update, (void *) entry);

    /*
     * Guard against broken systems.
     */
    event_request_timer(qmgr_deliver_abort, (void *) entry, var_daemon_timeout);
}