smtpd_dsn_fix.c

[詳解]

/*++
/* NAME
/*  smtpd_dsn_fix 3
/* SUMMARY
/*  fix DSN status
/* SYNOPSIS
/*  #include <smtpd_dsn_fix.h>
/*
/*  const char *smtpd_dsn_fix(status, reply_class)
/*  const char *status;
/*  const char *reply_class;
/* DESCRIPTION
/*  smtpd_dsn_fix() transforms DSN status codes according to the
/*  status information that is actually being reported. The
/*  following transformations are implemented:
/* .IP \(bu
/*  Transform a recipient address DSN into a sender address DSN
/*  when reporting sender address status information, and vice
/*  versa. This transformation may be needed because some Postfix
/*  access control features don't know whether the address being
/*  rejected is a sender or recipient. Examples are smtpd access
/*  tables, rbl reply templates, and the error mailer.
/* .IP \(bu
/*  Transform a sender or recipient address DSN into a non-address
/*  DSN when reporting non-address status information. For
/*  example, if something rejects HELO with DSN status 4.1.1
/*  (unknown recipient address), then we send the more neutral
/*  4.0.0 DSN instead. This transformation is needed when the
/*  same smtpd access map entry or rbl reply template is used
/*  for both address and non-address information.
/* .PP
/*  A non-address DSN is not transformed
/*  when reporting sender or recipient address status information,
/*  as there are many legitimate instances of such usage.
/*
/*  It is left up to the caller to update the initial DSN digit
/*  appropriately; in Postfix this is done as late as possible,
/*  because hard rejects may be changed into soft rejects for
/*  all kinds of reasons.
/*
/*  Arguments:
/* .IP status
/*  A DSN status as per RFC 3463.
/* .IP reply_class
/*  SMTPD_NAME_SENDER, SMTPD_NAME_RECIPIENT or some other
/*  null-terminated string.
/* 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 <ctype.h>
#include <string.h>

/* Utility library. */

#include <msg.h>

/* Global library. */

/* Application-specific. */

#include <smtpd_dsn_fix.h>

struct dsn_map {
    const char *micro_code;     /* Final digits in mailbox D.S.N. */
    const char *sender_dsn;     /* Replacement sender D.S.N. */
    const char *rcpt_dsn;       /* Replacement recipient D.S.N. */
};

static struct dsn_map dsn_map[] = {
    /* - Sender - Recipient */
    "1", SND_DSN, "4.1.1",      /* 4.1.1: Bad dest mbox addr */
    "2", "4.1.8", "4.1.2",      /* 4.1.2: Bad dest system addr */
    "3", "4.1.7", "4.1.3",      /* 4.1.3: Bad dest mbox addr syntax */
    "4", SND_DSN, "4.1.4",      /* 4.1.4: Dest mbox addr ambiguous */
    "5", "4.1.0", "4.1.5",      /* 4.1.5: Dest mbox addr valid */
    "6", SND_DSN, "4.1.6",      /* 4.1.6: Mailbox has moved */
    "7", "4.1.7", "4.1.3",      /* 4.1.7: Bad sender mbox addr syntax */
    "8", "4.1.8", "4.1.2",      /* 4.1.8: Bad sender system addr */
    0, "4.1.0", "4.1.0",        /* Default mapping */
};

/* smtpd_dsn_fix - fix DSN status */

const char *smtpd_dsn_fix(const char *status, const char *reply_class)
{
    struct dsn_map *dp;
    const char *result = status;

    /*
     * Update an address-specific DSN according to what is being rejected.
     */
    if (ISDIGIT(status[0]) && strncmp(status + 1, ".1.", 3) == 0) {

    /*
     * Fix recipient address DSN while rejecting a sender address. Don't
     * let future recipient-specific DSN codes slip past us.
     */
    if (strcmp(reply_class, SMTPD_NAME_SENDER) == 0) {
        for (dp = dsn_map; dp->micro_code != 0; dp++)
        if (strcmp(status + 4, dp->micro_code) == 0)
            break;
        result = dp->sender_dsn;
    }

    /*
     * Fix sender address DSN while rejecting a recipient address. Don't
     * let future sender-specific DSN codes slip past us.
     */
    else if (strcmp(reply_class, SMTPD_NAME_RECIPIENT) == 0) {
        for (dp = dsn_map; dp->micro_code != 0; dp++)
        if (strcmp(status + 4, dp->micro_code) == 0)
            break;
        result = dp->rcpt_dsn;
    }

    /*
     * Fix address-specific DSN while rejecting a non-address.
     */
    else {
        result = "4.0.0";
    }

    /*
     * Give them a clue of what is going on.
     */
    if (strcmp(status + 2, result + 2) != 0)
        msg_info("mapping DSN status %s into %s status %c%s",
             status, reply_class, status[0], result + 1);
    return (result);
    }

    /*
     * Don't update a non-address DSN. There are many legitimate uses for
     * these while rejecting address or non-address information.
     */
    else {
    return (status);
    }
}