/*
 * Copyright (c) 1994-2008 Carnegie Mellon University.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The name "Carnegie Mellon University" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For permission or any legal
 *    details, please contact
 *      Carnegie Mellon University
 *      Center for Technology Transfer and Enterprise Creation
 *      4615 Forbes Avenue
 *      Suite 302
 *      Pittsburgh, PA  15213
 *      (412) 268-7393, fax: (412) 268-7395
 *      innovation@andrew.cmu.edu
 *
 * 4. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Computing Services
 *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
 *
 * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
 * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * smmapd.c -- sendmail socket map daemon
 *
 *
 * From Sendmail Operations Guide:
 *
 * The socket map uses a simple request/reply protocol over TCP or
 * UNIX domain sockets to query an external server.  Both requests and
 * replies are text based and encoded as netstrings, i.e., a string
 * "hello there" becomes:
 *
 * 11:hello there,
 *
 * Note: neither requests nor replies end with CRLF.
 *
 * The request consists of the database map name and the lookup key
 * separated by a space character:
 *
 * <mapname> ’ ’ <key>
 *
 * The server responds with a status indicator and the result (if any):
 *
 * <status> ’ ’ <result>
 *
 * The status indicator is one of the following upper case words:
 *
 * OK           the key was found, result contains the looked up value
 * NOTFOUND     the key was not found, the result is empty
 * TEMP         a temporary failure occured
 * TIMEOUT      a timeout occured on the server side
 * PERM         a permanent failure occured
 *
 * In case of errors (status TEMP, TIMEOUT or PERM) the result field
 * may contain an explanatory message.
 *
 */

#include <config.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <stdio.h>
#include <string.h>
#include <sysexits.h>
#include <syslog.h>
#include <signal.h>

#include "acl.h"
#include "append.h"
#include "global.h"
#include "mboxlist.h"
#include "mupdate-client.h"
#include "proc.h"
#include "quota.h"
#include "util.h"
#include "xmalloc.h"
#include "xstrlcpy.h"
#include "xstrlcat.h"

/* generated headers are not necessarily in current directory */
#include "imap/imap_err.h"

const char *BB;
static int forcedowncase;

extern int optind;

static struct protstream *map_in, *map_out;
static const char *smmapd_clienthost;

/* current namespace */
static struct namespace map_namespace;

/* config.c info */
const int config_need_data = 0;

/* forward decls */
static int begin_handling(void);

static void smmapd_reset(void)
{
    if (map_in) {
        /* Flush the incoming buffer */
        prot_NONBLOCK(map_in);
        prot_fill(map_in);
        prot_free(map_in);
    }

    if (map_out) {
        /* Flush the outgoing buffer */
        prot_flush(map_out);
        prot_free(map_out);
    }

    smmapd_clienthost = "[local]";

    map_in = map_out = NULL;

    cyrus_reset_stdio();
}

void shut_down(int code) __attribute__((noreturn));
void shut_down(int code)
{
    in_shutdown = 1;

    smmapd_reset();

    cyrus_done();
    exit(code);
}

EXPORTED void fatal(const char* s, int code)
{
    static int recurse_code = 0;
    if (recurse_code) {
        /* We were called recursively. Just give up */
        exit(code);
    }
    recurse_code = code;
    syslog(LOG_ERR, "Fatal error: %s", s);
    abort();

    shut_down(code);
}

/*
 * run once when process is forked;
 * MUST NOT exit directly; must return with non-zero error code
 */
int service_init(int argc, char **argv, char **envp)
{
    int r;

    if (geteuid() == 0) fatal("must run as the Cyrus user", EX_USAGE);

    setproctitle_init(argc, argv, envp);

    signals_set_shutdown(&shut_down);
    signal(SIGPIPE, SIG_IGN);

    BB = config_getstring(IMAPOPT_POSTUSER);
    forcedowncase = config_getswitch(IMAPOPT_LMTP_DOWNCASE_RCPT);

    /* Set namespace */
    if ((r = mboxname_init_namespace(&map_namespace, 1)) != 0) {
        syslog(LOG_ERR, "%s", error_message(r));
        fatal(error_message(r), EX_CONFIG);
    }

    return 0;
}

/* Called by service API to shut down the service */
void service_abort(int error)
{
    shut_down(error);
}

int service_main(int argc __attribute__((unused)),
                 char **argv __attribute__((unused)),
                 char **envp __attribute__((unused)))
{
    const char *localip, *remoteip;
    map_in = prot_new(0, 0);
    map_out = prot_new(1, 1);
    prot_setflushonread(map_in, map_out);
    prot_settimeout(map_in, 360);

    smmapd_clienthost = get_clienthost(0, &localip, &remoteip);

    if (begin_handling() != 0) shut_down(0);

    /* prepare for new connection */
    smmapd_reset();
    return 0;
}

static int check_quotas(const char *name)
{
    quota_t qdiffs[QUOTA_NUMRESOURCES] = QUOTA_DIFFS_DONTCARE_INITIALIZER;
    char root[MAX_MAILBOX_NAME+1];

    /* just check the quotas we care about */
    qdiffs[QUOTA_STORAGE] = 0;
    qdiffs[QUOTA_MESSAGE] = 1;

    if (!quota_findroot(root, sizeof(root), name))
        return 0; /* no root, fine */

    return quota_check_useds(root, qdiffs);
}

static int verify_user(const char *key, struct auth_state *authstate)
{
    mbentry_t *mbentry = NULL;
    int r = 0;

    mbname_t *mbname = mbname_from_recipient(key, &map_namespace);

    if (forcedowncase) mbname_downcaseuser(mbname);

    /* see if its a shared mailbox address */
    if (!strcmpsafe(mbname_userid(mbname), BB)) {
        mbname_set_localpart(mbname, NULL);
        mbname_set_domain(mbname, NULL);
    }

    /*
     * check to see if mailbox exists and we can append to it:
     *
     * - must have posting privileges on shared folders
     * - don't care about ACL on INBOX (always allow post)
     * - must not be overquota
     */
    r = mboxlist_lookup(mbname_intname(mbname), &mbentry, NULL);
    if (r == IMAP_MAILBOX_NONEXISTENT && config_mupdate_server) {
        kick_mupdate();
        mboxlist_entry_free(&mbentry);
        r = mboxlist_lookup(mbname_intname(mbname), &mbentry, NULL);
    }
    if (r) goto done;

    if (!mbname_userid(mbname)) {
        long aclcheck = ACL_POST;
        int access = cyrus_acl_myrights(authstate, mbentry->acl);

        if ((access & aclcheck) != aclcheck) {
            r = (access & ACL_LOOKUP) ?
                IMAP_PERMISSION_DENIED : IMAP_MAILBOX_NONEXISTENT;
            goto done;
        }
    }

    if ((mbentry->mbtype & MBTYPE_REMOTE)) {
        struct hostent *hp;
        struct sockaddr_in sin,sfrom;
        char buf[512];
        int soc, rc;
        socklen_t x;
        /* XXX  Perhaps we should support the VRFY command in lmtpd
         * and then we could do a VRFY to the correct backend which
         * would also do a quotacheck.
         */

        /* proxy the request to the real backend server to
         * check the quota.  if this fails, just return 0
         * (assume under quota)
         */

        syslog(LOG_ERR, "verify_user(%s) proxying to host %s",
               mbname_userid(mbname), mbentry->server);

        hp = gethostbyname(mbentry->server);
        if (hp == (struct hostent*) 0) {
            syslog(LOG_ERR, "verify_user(%s) failed: can't find host %s",
                   mbname_userid(mbname), mbentry->server);
            goto done;
        }

        soc = socket(PF_INET, SOCK_STREAM, 0);
        if (soc < 0) {
            syslog(LOG_ERR, "verify_user(%s) failed: can't connect to %s",
                   mbname_userid(mbname), mbentry->server);
            goto done;
        }
        memcpy(&sin.sin_addr.s_addr,hp->h_addr,hp->h_length);
        sin.sin_family = AF_INET;

        /* XXX port should be configurable */
        sin.sin_port = htons(12345);

        if (connect(soc,(struct sockaddr *) &sin, sizeof(sin)) < 0) {
            syslog(LOG_ERR, "verify_user(%s) failed: can't connect to %s",
                   mbname_userid(mbname), mbentry->server);
            close(soc);
            goto done;
        }

        sprintf(buf,SIZE_T_FMT ":cyrus %s,%c",strlen(key)+6,key,4);
        sendto(soc,buf,strlen(buf),0,(struct sockaddr *)&sin,sizeof(sin));

        x = sizeof(sfrom);
        rc = recvfrom(soc,buf,512,0,(struct sockaddr *)&sfrom,&x);

        close(soc);

        if (rc >= 0) {
            buf[rc] = '\0';
            prot_printf(map_out, "%s", buf);
        }

        mboxlist_entry_free(&mbentry);
        mbname_free(&mbname);

        return -1;   /* tell calling function we already replied */
    }

    r = check_quotas(mbname_intname(mbname));

done:
    mboxlist_entry_free(&mbentry);
    if (r) syslog(LOG_DEBUG, "verify_user(%s) failed: %s", mbname_userid(mbname),
                  error_message(r));
    mbname_free(&mbname);

    return r;
}

/*
 * begin_handling: handle requests on a single connection.
 * returns non-zero if requested to stop handling new connections (SIGHUP)
 */
#define MAXREQUEST 1024         /* XXX  is this reasonable? */

static int begin_handling(void)
{
    int c;

    while ((c = prot_getc(map_in)) != EOF) {
        int r = 0, len = 0;
        struct auth_state *authstate = NULL;
        char request[MAXREQUEST+1];
        char *key = NULL;
        const char *errstring = NULL;

        if (signals_poll() == SIGHUP) {
            /* caught a SIGHUP, return */
            return 1;
        }

        prot_ungetc(c, map_in);
        c = getint32(map_in, &len);
        if (c == EOF) {
            errstring = prot_error(map_in);
            r = IMAP_IOERROR;
        }
        if (len == -1 || c != ':') {
            errstring = "missing length";
            r = IMAP_PROTOCOL_ERROR;
        }
        if (!r && prot_read(map_in, request, len) != len) {
            errstring = "request size doesn't match length";
            r = IMAP_PROTOCOL_ERROR;
        }
        if (!r && (c = prot_getc(map_in)) != ',') {
            errstring = "missing terminator";
            r = IMAP_PROTOCOL_ERROR;
        }

        if (!r) {
            request[len] = '\0';
            if (!(key = strchr(request, ' '))) {
                errstring = "missing key";
                r = IMAP_PROTOCOL_ERROR;
            }
        }

        if (!r) {
            *key++ = '\0';

            r = verify_user(key, authstate);
        }

        switch (r) {
        case -1:
            /* reply already sent */
            break;

        case 0:
            if (config_getswitch(IMAPOPT_AUDITLOG))
                syslog(LOG_NOTICE, "auditlog: ok userid=<%s> client=<%s>", key, smmapd_clienthost);
            prot_printf(map_out, SIZE_T_FMT ":OK %s,", 3+strlen(key), key);
            break;

        case IMAP_MAILBOX_NONEXISTENT:
            if (config_getswitch(IMAPOPT_AUDITLOG))
                syslog(LOG_NOTICE, "auditlog: nonexistent userid=<%s> client=<%s>", key, smmapd_clienthost);
            prot_printf(map_out, SIZE_T_FMT ":NOTFOUND %s,",
                        9+strlen(error_message(r)), error_message(r));
            break;

        case IMAP_QUOTA_EXCEEDED:
            if (config_getswitch(IMAPOPT_AUDITLOG))
                syslog(LOG_NOTICE, "auditlog: overquota userid=<%s> client=<%s>", key, smmapd_clienthost);
            if (!config_getswitch(IMAPOPT_LMTP_OVER_QUOTA_PERM_FAILURE)) {
                prot_printf(map_out, SIZE_T_FMT ":TEMP %s,", strlen(error_message(r))+5,
                            error_message(r));
                break;
            }
            /* fall through - permanent failure */

        default:
            if (config_getswitch(IMAPOPT_AUDITLOG))
                syslog(LOG_NOTICE, "auditlog: failed userid=<%s> client=<%s>", key ? key : "", smmapd_clienthost);
            if (errstring)
                prot_printf(map_out, SIZE_T_FMT ":PERM %s (%s),",
                            5+strlen(error_message(r))+3+strlen(errstring),
                            error_message(r), errstring);
            else
                prot_printf(map_out, SIZE_T_FMT ":PERM %s,",
                            5+strlen(error_message(r)), error_message(r));
            break;
        }
    }

    return 0;
}