bounce_one_service.c

[詳解]

/*++
/* NAME
/*  bounce_one_service 3
/* SUMMARY
/*  send non-delivery report to sender, server side
/* SYNOPSIS
/*  #include "bounce_service.h"
/*
/*  int     bounce_one_service(flags, queue_name, queue_id, encoding,
/*                  smtputf8, orig_sender, envid, ret,
/*                  rcpt_buf, dsn_buf, templates)
/*  int flags;
/*  char    *queue_name;
/*  char    *queue_id;
/*  char    *encoding;
/*  int smtputf8;
/*  char    *orig_sender;
/*  char    *envid;
/*  int ret;
/*  RCPT_BUF *rcpt_buf;
/*  DSN_BUF *dsn_buf;
/*  BOUNCE_TEMPLATES *templates;
/* DESCRIPTION
/*  This module implements the server side of the bounce_one()
/*  (send bounce message for one recipient) request.
/*
/*  When a message bounces, a full copy is sent to the originator,
/*  and an optional copy of the diagnostics with message headers is
/*  sent to the postmaster.  The result is non-zero when the operation
/*  should be tried again.
/*
/*  When a bounce is sent, the sender address is the empty
/*  address.  When a bounce bounces, an optional double bounce
/*  with the entire undeliverable mail is sent to the postmaster,
/*  with as sender address the double bounce address.
/* DIAGNOSTICS
/*  Fatal error: error opening existing file.
/* BUGS
/* SEE ALSO
/*  bounce(3) basic bounce service client interface
/* 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
/*--*/

/* System library. */

#include <sys_defs.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <ctype.h>

/* Utility library. */

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

/* Global library. */

#include <mail_params.h>
#include <post_mail.h>
#include <mail_addr.h>
#include <mail_error.h>
#include <bounce.h>
#include <dsn_mask.h>
#include <rec_type.h>

/* Application-specific. */

#include "bounce_service.h"

#define STR vstring_str

/* bounce_one_service - send a bounce for one recipient */

int     bounce_one_service(int flags, char *queue_name, char *queue_id,
                       char *encoding, int smtputf8,
                       char *orig_sender, char *dsn_envid,
                       int dsn_ret, RCPT_BUF *rcpt_buf,
                       DSN_BUF *dsn_buf, BOUNCE_TEMPLATES *ts)
{
    BOUNCE_INFO *bounce_info;
    int     bounce_status = 1;
    int     postmaster_status = 1;
    VSTREAM *bounce;
    int     notify_mask = name_mask(VAR_NOTIFY_CLASSES, mail_error_masks,
                    var_notify_classes);
    VSTRING *new_id = vstring_alloc(10);

    /*
     * Initialize. Open queue file, bounce log, etc.
     */
    bounce_info = bounce_mail_one_init(queue_name, queue_id, encoding,
                       smtputf8, dsn_envid, rcpt_buf,
                       dsn_buf, ts->failure);

#define NULL_SENDER     MAIL_ADDR_EMPTY /* special address */
#define NULL_TRACE_FLAGS    0

    /*
     * The choice of bounce sender address depends on the original sender
     * address. For a single bounce (a non-delivery notification to the
     * message originator), the sender address is the empty string. For a
     * double bounce (typically a failed single bounce, or a postmaster
     * notification that was produced by any of the mail processes) the
     * sender address is defined by the var_double_bounce_sender
     * configuration variable. When a double bounce cannot be delivered, the
     * queue manager blackholes the resulting triple bounce message.
     */

    /*
     * Double bounce failed. Never send a triple bounce.
     * 
     * However, this does not prevent double bounces from bouncing on other
     * systems. In order to cope with this, either the queue manager must
     * recognize the double-bounce original sender address and discard mail,
     * or every delivery agent must recognize the double-bounce sender
     * address and substitute something else so mail does not come back at
     * us.
     */
    if (strcasecmp_utf8(orig_sender, mail_addr_double_bounce()) == 0) {
    msg_warn("%s: undeliverable postmaster notification discarded",
         queue_id);
    bounce_status = 0;
    }

    /*
     * Single bounce failed. Optionally send a double bounce to postmaster,
     * subject to notify_classes restrictions.
     */
#define ANY_BOUNCE (MAIL_ERROR_2BOUNCE | MAIL_ERROR_BOUNCE)
#define SEND_POSTMASTER_ANY_BOUNCE_NOTICE (notify_mask & ANY_BOUNCE)

    else if (*orig_sender == 0) {
    if (!SEND_POSTMASTER_ANY_BOUNCE_NOTICE) {
        bounce_status = 0;
    } else {
        if ((bounce = post_mail_fopen_nowait(mail_addr_double_bounce(),
                         var_2bounce_rcpt,
                         MAIL_SRC_MASK_BOUNCE,
                         NULL_TRACE_FLAGS,
                         smtputf8,
                         new_id)) != 0) {

        /*
         * Double bounce to Postmaster. This is the last opportunity
         * for this message to be delivered. Send the text with
         * reason for the bounce, and the headers of the original
         * message. Don't bother sending the boiler-plate text.
         */
        if (!bounce_header(bounce, bounce_info, var_2bounce_rcpt,
                   POSTMASTER_COPY)
            && bounce_recipient_log(bounce, bounce_info) == 0
            && bounce_header_dsn(bounce, bounce_info) == 0
            && bounce_recipient_dsn(bounce, bounce_info) == 0)
            bounce_original(bounce, bounce_info, DSN_RET_FULL);
        bounce_status = post_mail_fclose(bounce);
        if (bounce_status == 0)
            msg_info("%s: postmaster non-delivery notification: %s",
                 queue_id, STR(new_id));
        }
    }
    }

    /*
     * Non-bounce failed. Send a single bounce, subject to DSN NOTIFY
     * restrictions.
     */
    else {
    RECIPIENT *rcpt = &bounce_info->rcpt_buf->rcpt;

    if (rcpt->dsn_notify != 0       /* compat */
        && (rcpt->dsn_notify & DSN_NOTIFY_FAILURE) == 0) {
        bounce_status = 0;
    } else {
        if ((bounce = post_mail_fopen_nowait(NULL_SENDER, orig_sender,
                         MAIL_SRC_MASK_BOUNCE,
                         NULL_TRACE_FLAGS,
                         smtputf8,
                         new_id)) != 0) {

        /*
         * Send the bounce message header, some boilerplate text that
         * pretends that we are a polite mail system, the text with
         * reason for the bounce, and a copy of the original message.
         */
        if (bounce_header(bounce, bounce_info, orig_sender,
                  NO_POSTMASTER_COPY) == 0
            && bounce_boilerplate(bounce, bounce_info) == 0
            && bounce_recipient_log(bounce, bounce_info) == 0
            && bounce_header_dsn(bounce, bounce_info) == 0
            && bounce_recipient_dsn(bounce, bounce_info) == 0)
            bounce_original(bounce, bounce_info, dsn_ret ?
                    dsn_ret : DSN_RET_FULL);
        bounce_status = post_mail_fclose(bounce);
        if (bounce_status == 0)
            msg_info("%s: sender non-delivery notification: %s",
                 queue_id, STR(new_id));
        }
    }

    /*
     * Optionally send a postmaster notice, subject to notify_classes
     * restrictions.
     * 
     * This postmaster notice is not critical, so if it fails don't
     * retransmit the bounce that we just generated, just log a warning.
     */
#define SEND_POSTMASTER_SINGLE_BOUNCE_NOTICE (notify_mask & MAIL_ERROR_BOUNCE)

    if (bounce_status == 0 && SEND_POSTMASTER_SINGLE_BOUNCE_NOTICE
        && strcasecmp_utf8(orig_sender, mail_addr_double_bounce()) != 0) {

        /*
         * Send the text with reason for the bounce, and the headers of
         * the original message. Don't bother sending the boiler-plate
         * text. This postmaster notice is not critical, so if it fails
         * don't retransmit the bounce that we just generated, just log a
         * warning.
         */
        if ((bounce = post_mail_fopen_nowait(mail_addr_double_bounce(),
                         var_bounce_rcpt,
                         MAIL_SRC_MASK_BOUNCE,
                         NULL_TRACE_FLAGS,
                         smtputf8,
                         new_id)) != 0) {
        if (bounce_header(bounce, bounce_info, var_bounce_rcpt,
                  POSTMASTER_COPY) == 0
            && bounce_recipient_log(bounce, bounce_info) == 0
            && bounce_header_dsn(bounce, bounce_info) == 0
            && bounce_recipient_dsn(bounce, bounce_info) == 0)
            bounce_original(bounce, bounce_info, DSN_RET_HDRS);
        postmaster_status = post_mail_fclose(bounce);
        if (postmaster_status == 0)
            msg_info("%s: postmaster non-delivery notification: %s",
                 queue_id, STR(new_id));
        }
        if (postmaster_status)
        msg_warn("%s: postmaster notice failed while bouncing to %s",
             queue_id, orig_sender);
    }
    }

    /*
     * Optionally, delete the recipient from the queue file.
     */
    if (bounce_status == 0 && (flags & BOUNCE_FLAG_DELRCPT))
    bounce_delrcpt_one(bounce_info);

    /*
     * Cleanup.
     */
    bounce_mail_free(bounce_info);
    vstring_free(new_id);

    return (bounce_status);
}