Patrick Welche <prlw1@cam.ac.uk>

[netbsd-mini2440.git] / external / ibm-public / postfix / dist / src / local / alias.c

/*      $NetBSD$        */

/*++
/* NAME
/*      alias 3
/* SUMMARY
/*      alias data base lookups
/* SYNOPSIS
/*      #include "local.h"
/*
/*      int     deliver_alias(state, usr_attr, name, statusp)
/*      LOCAL_STATE state;
/*      USER_ATTR usr_attr;
/*      char    *name;
/*      int     *statusp;
/* DESCRIPTION
/*      deliver_alias() looks up the expansion of the recipient in
/*      the global alias database and delivers the message to the
/*      listed destinations. The result is zero when no alias was found
/*      or when the message should be delivered to the user instead.
/*
/*      deliver_alias() has wired-in knowledge about a few reserved
/*      recipient names.
/* .IP \(bu
/*      When no alias is found for the local \fIpostmaster\fR or
/*      \fImailer-daemon\fR a warning is issued and the message
/*      is discarded.
/* .IP \(bu
/*      When an alias exists for recipient \fIname\fR, and an alias
/*      exists for \fIowner-name\fR, the sender address is changed
/*      to \fIowner-name\fR, and the owner delivery attribute is
/*      set accordingly. This feature is disabled with
/*      "owner_request_special = no".
/* .PP
/*      Arguments:
/* .IP state
/*      Attributes that specify the message, recipient and more.
/*      Expansion type (alias, include, .forward).
/*      A table with the results from expanding aliases or lists.
/*      A table with delivered-to: addresses taken from the message.
/* .IP usr_attr
/*      User attributes (rights, environment).
/* .IP name
/*      The alias to be looked up.
/* .IP statusp
/*      Delivery status. See below.
/* DIAGNOSTICS
/*      Fatal errors: out of memory. The delivery status is non-zero
/*      when delivery should be tried again.
/* 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 <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>

#ifdef STRCASECMP_IN_STRINGS_H
#include <strings.h>
#endif

/* Utility library. */

#include <msg.h>
#include <htable.h>
#include <dict.h>
#include <argv.h>
#include <stringops.h>
#include <mymalloc.h>
#include <vstring.h>
#include <vstream.h>

/* Global library. */

#include <mail_params.h>
#include <defer.h>
#include <maps.h>
#include <bounce.h>
#include <mypwd.h>
#include <canon_addr.h>
#include <sent.h>
#include <trace.h>
#include <dsn_mask.h>

/* Application-specific. */

#include "local.h"

/* Application-specific. */

#define NO      0
#define YES     1

/* dict_owner - find out alias database owner */

static uid_t dict_owner(char *table)
{
    const char *myname = "dict_owner";
    DICT   *dict;
    struct stat st;

    /*
     * This code sits here for now, but we may want to move it to the library
     * some time.
     */
    if ((dict = dict_handle(table)) == 0)
        msg_panic("%s: can't find dictionary: %s", myname, table);
    if (dict->stat_fd < 0)
        return (0);
    if (fstat(dict->stat_fd, &st) < 0)
        msg_fatal("%s: fstat dictionary %s: %m", myname, table);
    return (st.st_uid);
}

/* deliver_alias - expand alias file entry */

int     deliver_alias(LOCAL_STATE state, USER_ATTR usr_attr,
                              char *name, int *statusp)
{
    const char *myname = "deliver_alias";
    const char *alias_result;
    char   *saved_alias_result;
    char   *owner;
    char  **cpp;
    uid_t   alias_uid;
    struct mypasswd *alias_pwd;
    VSTRING *canon_owner;
    DICT   *dict;
    const char *owner_rhs;              /* owner alias, RHS */
    int     alias_count;
    int     dsn_notify;
    char   *dsn_envid;
    int     dsn_ret;
    const char *dsn_orcpt;

    /*
     * Make verbose logging easier to understand.
     */
    state.level++;
    if (msg_verbose)
        MSG_LOG_STATE(myname, state);

    /*
     * DUPLICATE/LOOP ELIMINATION
     * 
     * We cannot do duplicate elimination here. Sendmail compatibility requires
     * that we allow multiple deliveries to the same alias, even recursively!
     * For example, we must deliver to mailbox any messags that are addressed
     * to the alias of a user that lists that same alias in her own .forward
     * file. Yuck! This is just an example of some really perverse semantics
     * that people will expect Postfix to implement just like sendmail.
     * 
     * We can recognize one special case: when an alias includes its own name,
     * deliver to the user instead, just like sendmail. Otherwise, we just
     * bail out when nesting reaches some unreasonable depth, and blame it on
     * a possible alias loop.
     */
    if (state.msg_attr.exp_from != 0
        && strcasecmp(state.msg_attr.exp_from, name) == 0)
        return (NO);
    if (state.level > 100) {
        msg_warn("alias database loop for %s", name);
        dsb_simple(state.msg_attr.why, "5.4.6",
                   "alias database loop for %s", name);
        *statusp = bounce_append(BOUNCE_FLAGS(state.request),
                                 BOUNCE_ATTR(state.msg_attr));
        return (YES);
    }
    state.msg_attr.exp_from = name;

    /*
     * There are a bunch of roles that we're trying to keep track of.
     * 
     * First, there's the issue of whose rights should be used when delivering
     * to "|command" or to /file/name. With alias databases, the rights are
     * those of who owns the alias, i.e. the database owner. With aliases
     * owned by root, a default user is used instead. When an alias with
     * default rights references an include file owned by an ordinary user,
     * we must use the rights of the include file owner, otherwise the
     * include file owner could take control of the default account.
     * 
     * Secondly, there's the question of who to notify of delivery problems.
     * With aliases that have an owner- alias, the latter is used to set the
     * sender and owner attributes. Otherwise, the owner attribute is reset
     * (the alias is globally visible and could be sent to by anyone).
     */
    for (cpp = alias_maps->argv->argv; *cpp; cpp++) {
        if ((dict = dict_handle(*cpp)) == 0)
            msg_panic("%s: dictionary not found: %s", myname, *cpp);
        if ((alias_result = dict_get(dict, name)) != 0) {
            if (msg_verbose)
                msg_info("%s: %s: %s = %s", myname, *cpp, name, alias_result);

            /*
             * Don't expand a verify-only request.
             */
            if (state.request->flags & DEL_REQ_FLAG_MTA_VRFY) {
                dsb_simple(state.msg_attr.why, "2.0.0",
                           "aliased to %s", alias_result);
                *statusp = sent(BOUNCE_FLAGS(state.request),
                                SENT_ATTR(state.msg_attr));
                return (YES);
            }

            /*
             * DELIVERY POLICY
             * 
             * Update the expansion type attribute, so we can decide if
             * deliveries to |command and /file/name are allowed at all.
             */
            state.msg_attr.exp_type = EXPAND_TYPE_ALIAS;

            /*
             * DELIVERY RIGHTS
             * 
             * What rights to use for |command and /file/name deliveries? The
             * command and file code will use default rights when the alias
             * database is owned by root, otherwise it will use the rights of
             * the alias database owner.
             */
            if ((alias_uid = dict_owner(*cpp)) == 0) {
                alias_pwd = 0;
                RESET_USER_ATTR(usr_attr, state.level);
            } else {
                if ((alias_pwd = mypwuid(alias_uid)) == 0) {
                    msg_warn("cannot find alias database owner for %s", *cpp);
                    dsb_simple(state.msg_attr.why, "4.3.0",
                               "cannot find alias database owner");
                    *statusp = defer_append(BOUNCE_FLAGS(state.request),
                                            BOUNCE_ATTR(state.msg_attr));
                    return (YES);
                }
                SET_USER_ATTR(usr_attr, alias_pwd, state.level);
            }

            /*
             * WHERE TO REPORT DELIVERY PROBLEMS.
             * 
             * Use the owner- alias if one is specified, otherwise reset the
             * owner attribute and use the include file ownership if we can.
             * Save the dict_lookup() result before something clobbers it.
             * 
             * Don't match aliases that are based on regexps.
             */
#define OWNER_ASSIGN(own) \
            (own = (var_ownreq_special == 0 ? 0 : \
            concatenate("owner-", name, (char *) 0)))

            saved_alias_result = mystrdup(alias_result);
            if (OWNER_ASSIGN(owner) != 0
                && (owner_rhs = maps_find(alias_maps, owner, DICT_FLAG_NONE)) != 0) {
                canon_owner = canon_addr_internal(vstring_alloc(10),
                                     var_exp_own_alias ? owner_rhs : owner);
                /* Set envelope sender and owner attribute. */
                SET_OWNER_ATTR(state.msg_attr, STR(canon_owner), state.level);
            } else {
                canon_owner = 0;
                /* Note: this does not reset the envelope sender. */
                RESET_OWNER_ATTR(state.msg_attr, state.level);
            }

            /*
             * EXTERNAL LOOP CONTROL
             * 
             * Set the delivered message attribute to the recipient, so that
             * this message will list the correct forwarding address.
             */
            if (var_frozen_delivered == 0)
                state.msg_attr.delivered = state.msg_attr.rcpt.address;

            /*
             * Deliver.
             */
            alias_count = 0;
            if (dict_errno != 0) {
                dsb_simple(state.msg_attr.why, "4.3.0",
                           "alias database unavailable");
                *statusp = defer_append(BOUNCE_FLAGS(state.request),
                                        BOUNCE_ATTR(state.msg_attr));
            } else {

                /*
                 * XXX DSN
                 * 
                 * When delivering to a mailing list (i.e. the envelope sender
                 * is replaced) the ENVID, NOTIFY, RET, and ORCPT parameters
                 * which accompany the redistributed message MUST NOT be
                 * derived from those of the original message.
                 * 
                 * When delivering to an alias (i.e. the envelope sender is not
                 * replaced) any ENVID, RET, or ORCPT parameters are
                 * propagated to all forwarding addresses associated with
                 * that alias.  The NOTIFY parameter is propagated to the
                 * forwarding addresses, except that any SUCCESS keyword is
                 * removed.
                 */
#define DSN_SAVE_UPDATE(saved, old, new) do { \
        saved = old; \
        old = new; \
    } while (0)

                DSN_SAVE_UPDATE(dsn_notify, state.msg_attr.rcpt.dsn_notify,
                                dsn_notify == DSN_NOTIFY_SUCCESS ?
                                DSN_NOTIFY_NEVER :
                                dsn_notify & ~DSN_NOTIFY_SUCCESS);
                if (canon_owner != 0) {
                    DSN_SAVE_UPDATE(dsn_envid, state.msg_attr.dsn_envid, "");
                    DSN_SAVE_UPDATE(dsn_ret, state.msg_attr.dsn_ret, 0);
                    DSN_SAVE_UPDATE(dsn_orcpt, state.msg_attr.rcpt.dsn_orcpt, "");
                    state.msg_attr.rcpt.orig_addr = "";
                }
                *statusp =
                    deliver_token_string(state, usr_attr, saved_alias_result,
                                         &alias_count);
#if 0
                if (var_ownreq_special
                    && strncmp("owner-", state.msg_attr.sender, 6) != 0
                    && alias_count > 10)
                    msg_warn("mailing list \"%s\" needs an \"owner-%s\" alias",
                             name, name);
#endif
                if (alias_count < 1) {
                    msg_warn("no recipient in alias lookup result for %s", name);
                    dsb_simple(state.msg_attr.why, "4.3.0",
                               "alias database unavailable");
                    *statusp = defer_append(BOUNCE_FLAGS(state.request),
                                            BOUNCE_ATTR(state.msg_attr));
                } else {

                    /*
                     * XXX DSN
                     * 
                     * When delivering to a mailing list (i.e. the envelope
                     * sender address is replaced) and NOTIFY=SUCCESS was
                     * specified, report a DSN of "delivered".
                     * 
                     * When delivering to an alias (i.e. the envelope sender
                     * address is not replaced) and NOTIFY=SUCCESS was
                     * specified, report a DSN of "expanded".
                     */
                    if (dsn_notify & DSN_NOTIFY_SUCCESS) {
                        state.msg_attr.rcpt.dsn_notify = dsn_notify;
                        if (canon_owner != 0) {
                            state.msg_attr.dsn_envid = dsn_envid;
                            state.msg_attr.dsn_ret = dsn_ret;
                            state.msg_attr.rcpt.dsn_orcpt = dsn_orcpt;
                        }
                        dsb_update(state.msg_attr.why, "2.0.0", canon_owner ?
                                   "delivered" : "expanded",
                                   DSB_SKIP_RMTA, DSB_SKIP_REPLY,
                                   "alias expanded");
                        (void) trace_append(BOUNCE_FLAG_NONE,
                                            SENT_ATTR(state.msg_attr));
                    }
                }
            }
            myfree(saved_alias_result);
            if (owner)
                myfree(owner);
            if (canon_owner)
                vstring_free(canon_owner);
            if (alias_pwd)
                mypwfree(alias_pwd);
            return (YES);
        }

        /*
         * If the alias database was inaccessible for some reason, defer
         * further delivery for the current top-level recipient.
         */
        if (dict_errno != 0) {
            dsb_simple(state.msg_attr.why, "4.3.0",
                       "alias database unavailable");
            *statusp = defer_append(BOUNCE_FLAGS(state.request),
                                    BOUNCE_ATTR(state.msg_attr));
            return (YES);
        } else {
            if (msg_verbose)
                msg_info("%s: %s: %s not found", myname, *cpp, name);
        }
    }

    /*
     * Try delivery to a local user instead.
     */
    return (NO);
}