/*
 * Copyright (c) 1997 - 2008 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * 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. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "iprop.h"

RCSID("$Id$");

static const char *config_name = "ipropd-slave";

static krb5_log_facility *log_facility;
static char *server_time_lost = "5 min";
static int time_before_lost;
const char *slave_str = NULL;

static int
connect_to_master (krb5_context context, const char *master,
		   const char *port_str)
{
    char port[NI_MAXSERV];
    struct addrinfo *ai, *a;
    struct addrinfo hints;
    int error;
    int s = -1;

    memset (&hints, 0, sizeof(hints));
    hints.ai_socktype = SOCK_STREAM;

    if (port_str == NULL) {
	snprintf(port, sizeof(port), "%u", IPROP_PORT);
	port_str = port;
    }

    error = getaddrinfo (master, port_str, &hints, &ai);
    if (error) {
	krb5_warnx(context, "Failed to get address of to %s: %s", 
		   master, gai_strerror(error));
	return -1;
    }

    for (a = ai; a != NULL; a = a->ai_next) {
	char node[NI_MAXHOST];
	error = getnameinfo(a->ai_addr, a->ai_addrlen, 
			    node, sizeof(node), NULL, 0, NI_NUMERICHOST);
	if (error)
	    strlcpy(node, "[unknown-addr]", sizeof(node));

	s = socket (a->ai_family, a->ai_socktype, a->ai_protocol);
	if (s < 0)
	    continue;
	if (connect (s, a->ai_addr, a->ai_addrlen) < 0) {
	    krb5_warn(context, errno, "connection failed to %s[%s]",
		      master, node);
	    close (s);
	    continue;
	}
	krb5_warnx(context, "connection successful "
		   "to master: %s[%s]", master, node);
	break;
    }
    freeaddrinfo (ai);

    if (a == NULL)
	return -1;

    return s;
}

static void
get_creds(krb5_context context, const char *keytab_str,
	  krb5_ccache *cache, const char *serverhost)
{
    krb5_keytab keytab;
    krb5_principal client;
    krb5_error_code ret;
    krb5_get_init_creds_opt *init_opts;
    krb5_creds creds;
    char *server;
    char keytab_buf[256];

    if (keytab_str == NULL) {
	ret = krb5_kt_default_name (context, keytab_buf, sizeof(keytab_buf));
	if (ret)
	    krb5_err (context, 1, ret, "krb5_kt_default_name");
	keytab_str = keytab_buf;
    }

    ret = krb5_kt_resolve(context, keytab_str, &keytab);
    if(ret)
	krb5_err(context, 1, ret, "%s", keytab_str);


    ret = krb5_sname_to_principal (context, slave_str, IPROP_NAME,
				   KRB5_NT_SRV_HST, &client);
    if (ret) krb5_err(context, 1, ret, "krb5_sname_to_principal");

    ret = krb5_get_init_creds_opt_alloc(context, &init_opts);
    if (ret) krb5_err(context, 1, ret, "krb5_get_init_creds_opt_alloc");

    asprintf (&server, "%s/%s", IPROP_NAME, serverhost);
    if (server == NULL)
	krb5_errx (context, 1, "malloc: no memory");

    ret = krb5_get_init_creds_keytab(context, &creds, client, keytab,
				     0, server, init_opts);
    free (server);
    krb5_get_init_creds_opt_free(context, init_opts);
    if(ret) krb5_err(context, 1, ret, "krb5_get_init_creds");

    ret = krb5_kt_close(context, keytab);
    if(ret) krb5_err(context, 1, ret, "krb5_kt_close");

    ret = krb5_cc_new_unique(context, krb5_cc_type_memory, NULL, cache);
    if(ret) krb5_err(context, 1, ret, "krb5_cc_new_unique");

    ret = krb5_cc_initialize(context, *cache, client);
    if(ret) krb5_err(context, 1, ret, "krb5_cc_initialize");

    ret = krb5_cc_store_cred(context, *cache, &creds);
    if(ret) krb5_err(context, 1, ret, "krb5_cc_store_cred");

    krb5_free_cred_contents(context, &creds);
    krb5_free_principal(context, client);
}

static krb5_error_code
ihave (krb5_context context, krb5_auth_context auth_context,
       int fd, uint32_t version)
{
    int ret;
    u_char buf[8];
    krb5_storage *sp;
    krb5_data data;

    sp = krb5_storage_from_mem (buf, 8);
    krb5_store_int32 (sp, I_HAVE);
    krb5_store_int32 (sp, version);
    krb5_storage_free (sp);
    data.length = 8;
    data.data   = buf;

    ret = krb5_write_priv_message(context, auth_context, &fd, &data);
    if (ret)
	krb5_warn (context, ret, "krb5_write_message");
    return ret;
}

static void
receive_loop (krb5_context context,
	      krb5_storage *sp,
	      kadm5_server_context *server_context)
{
    int ret;
    off_t left, right;
    void *buf;
    int32_t vers, vers2;
    ssize_t sret;

    /*
     * Seek to the current version of the local database.
     */
    do {
	int32_t len, timestamp, tmp;
	enum kadm_ops op;

	if(krb5_ret_int32 (sp, &vers) != 0)
	    return;
	krb5_ret_int32 (sp, &timestamp);
	krb5_ret_int32 (sp, &tmp);
	op = tmp;
	krb5_ret_int32 (sp, &len);
	if (vers <= server_context->log_context.version)
	    krb5_storage_seek(sp, len + 8, SEEK_CUR);
    } while(vers <= server_context->log_context.version);

    /*
     * Read up rest of the entires into the memory...
     */
    left  = krb5_storage_seek (sp, -16, SEEK_CUR);
    right = krb5_storage_seek (sp, 0, SEEK_END);
    buf = malloc (right - left);
    if (buf == NULL && (right - left) != 0)
	krb5_errx (context, 1, "malloc: no memory");

    /*
     * ...and then write them out to the on-disk log.
     */
    krb5_storage_seek (sp, left, SEEK_SET);
    krb5_storage_read (sp, buf, right - left);
    sret = write (server_context->log_context.log_fd, buf, right-left);
    if (sret != right - left)
	krb5_err(context, 1, errno, "Failed to write log to disk");
    ret = fsync (server_context->log_context.log_fd);
    if (ret)
	krb5_err(context, 1, errno, "Failed to sync log to disk");
    free (buf);

    /*
     * Go back to the startpoint and start to commit the entires to
     * the database.
     */
    krb5_storage_seek (sp, left, SEEK_SET);

    for(;;) {
	int32_t len, len2, timestamp, tmp;
	off_t cur, cur2;
	enum kadm_ops op;

	if(krb5_ret_int32 (sp, &vers) != 0)
	    break;
	ret = krb5_ret_int32 (sp, &timestamp);
	if (ret) krb5_errx(context, 1, "entry %ld: too short", (long)vers);
	ret = krb5_ret_int32 (sp, &tmp);
	if (ret) krb5_errx(context, 1, "entry %ld: too short", (long)vers);
	op = tmp;
	ret = krb5_ret_int32 (sp, &len);
	if (ret) krb5_errx(context, 1, "entry %ld: too short", (long)vers);
	if (len < 0)
	    krb5_errx(context, 1, "log is corrupted, "
		      "negative length of entry version %ld: %ld",
		      (long)vers, (long)len);
	cur = krb5_storage_seek(sp, 0, SEEK_CUR);

	krb5_warnx (context, "replaying entry %d", (int)vers);

	ret = kadm5_log_replay (server_context,
				op, vers, len, sp);
	if (ret) {
	    const char *s = krb5_get_error_message(server_context->context, ret);
	    krb5_warnx (context,
			"kadm5_log_replay: %ld. Lost entry entry, "
			"Database out of sync ?: %s (%d)",
			(long)vers, s ? s : "unknown error", ret);
	    krb5_free_error_message(context, s);
	}

	{
	    /*
	     * Make sure the krb5_log_replay does the right thing wrt
	     * reading out data from the sp.
	     */
	    cur2 = krb5_storage_seek(sp, 0, SEEK_CUR);
	    if (cur + len != cur2)
		krb5_errx(context, 1,
			  "kadm5_log_reply version: %ld didn't read the whole entry",
			  (long)vers);
	}

	if (krb5_ret_int32 (sp, &len2) != 0)
	    krb5_errx(context, 1, "entry %ld: postamble too short", (long)vers);
	if(krb5_ret_int32 (sp, &vers2) != 0)
	    krb5_errx(context, 1, "entry %ld: postamble too short", (long)vers);

	if (len != len2)
	    krb5_errx(context, 1, "entry %ld: len != len2", (long)vers);
	if (vers != vers2)
	    krb5_errx(context, 1, "entry %ld: vers != vers2", (long)vers);
    }

    /*
     * Update version
     */

    server_context->log_context.version = vers;
}

static void
receive (krb5_context context,
	 krb5_storage *sp,
	 kadm5_server_context *server_context)
{
    int ret;

    ret = server_context->db->hdb_open(context,
				       server_context->db,
				       O_RDWR | O_CREAT, 0600);
    if (ret)
	krb5_err (context, 1, ret, "db->open");

    receive_loop (context, sp, server_context);

    ret = server_context->db->hdb_close (context, server_context->db);
    if (ret)
	krb5_err (context, 1, ret, "db->close");
}

static void
send_im_here (krb5_context context, int fd,
	      krb5_auth_context auth_context)
{
    krb5_storage *sp;
    krb5_data data;
    int ret;

    ret = krb5_data_alloc (&data, 4);
    if (ret)
	krb5_err (context, 1, ret, "send_im_here");

    sp = krb5_storage_from_data (&data);
    if (sp == NULL)
	krb5_errx (context, 1, "krb5_storage_from_data");
    krb5_store_int32(sp, I_AM_HERE);
    krb5_storage_free(sp);

    ret = krb5_write_priv_message(context, auth_context, &fd, &data);
    krb5_data_free(&data);

    if (ret)
	krb5_err (context, 1, ret, "krb5_write_priv_message");
}

static krb5_error_code
receive_everything (krb5_context context, int fd,
		    kadm5_server_context *server_context,
		    krb5_auth_context auth_context)
{
    int ret;
    krb5_data data;
    int32_t vno = 0;
    int32_t opcode;
    krb5_storage *sp;

    char *dbname;
    HDB *mydb;

    krb5_warnx(context, "receive complete database");

    asprintf(&dbname, "%s-NEW", server_context->db->hdb_name);
    ret = hdb_create(context, &mydb, dbname);
    if(ret)
	krb5_err(context,1, ret, "hdb_create");
    free(dbname);

    ret = hdb_set_master_keyfile (context,
				  mydb, server_context->config.stash_file);
    if(ret)
	krb5_err(context,1, ret, "hdb_set_master_keyfile");

    /* I really want to use O_EXCL here, but given that I can't easily clean
       up on error, I won't */
    ret = mydb->hdb_open(context, mydb, O_RDWR | O_CREAT | O_TRUNC, 0600);
    if (ret)
	krb5_err (context, 1, ret, "db->open");

    sp = NULL;
    do {
	ret = krb5_read_priv_message(context, auth_context, &fd, &data);

	if (ret) {
	    krb5_warn (context, ret, "krb5_read_priv_message");
	    goto cleanup;
	}

	sp = krb5_storage_from_data (&data);
	if (sp == NULL)
	    krb5_errx (context, 1, "krb5_storage_from_data");
	krb5_ret_int32 (sp, &opcode);
	if (opcode == ONE_PRINC) {
	    krb5_data fake_data;
	    hdb_entry_ex entry;

	    krb5_storage_free(sp);

	    fake_data.data   = (char *)data.data + 4;
	    fake_data.length = data.length - 4;

	    memset(&entry, 0, sizeof(entry));

	    ret = hdb_value2entry (context, &fake_data, &entry.entry);
	    if (ret)
		krb5_err (context, 1, ret, "hdb_value2entry");
	    ret = mydb->hdb_store(server_context->context,
				  mydb,
				  0, &entry);
	    if (ret)
		krb5_err (context, 1, ret, "hdb_store");

	    hdb_free_entry (context, &entry);
	    krb5_data_free (&data);
	} else if (opcode == NOW_YOU_HAVE)
	    ;
	else
	    krb5_errx (context, 1, "strange opcode %d", opcode);
    } while (opcode == ONE_PRINC);

    if (opcode != NOW_YOU_HAVE)
	krb5_errx (context, 1, "receive_everything: strange %d", opcode);

    krb5_ret_int32 (sp, &vno);
    krb5_storage_free(sp);

    ret = kadm5_log_reinit (server_context);
    if (ret)
	krb5_err(context, 1, ret, "kadm5_log_reinit");

    ret = kadm5_log_set_version (server_context, vno - 1);
    if (ret)
	krb5_err (context, 1, ret, "kadm5_log_set_version");

    ret = kadm5_log_nop (server_context);
    if (ret)
	krb5_err (context, 1, ret, "kadm5_log_nop");

    ret = mydb->hdb_rename (context, mydb, server_context->db->hdb_name);
    if (ret)
	krb5_err (context, 1, ret, "db->rename");

 cleanup:
    krb5_data_free (&data);

    ret = mydb->hdb_close (context, mydb);
    if (ret)
	krb5_err (context, 1, ret, "db->close");

    ret = mydb->hdb_destroy (context, mydb);
    if (ret)
	krb5_err (context, 1, ret, "db->destroy");

    krb5_warnx(context, "receive complete database, version %ld", (long)vno);
    return ret;
}

static char *config_file;
static char *realm;
static int version_flag;
static int help_flag;
static char *keytab_str;
static char *port_str;
#ifdef SUPPORT_DETACH
static int detach_from_console = 0;
#endif

static struct getargs args[] = {
    { "config-file", 'c', arg_string, &config_file },
    { "realm", 'r', arg_string, &realm },
    { "keytab", 'k', arg_string, &keytab_str,
      "keytab to get authentication from", "kspec" },
    { "time-lost", 0, arg_string, &server_time_lost,
      "time before server is considered lost", "time" },
    { "port", 0, arg_string, &port_str,
      "port ipropd-slave will connect to", "port"},
#ifdef SUPPORT_DETACH
    { "detach", 0, arg_flag, &detach_from_console,
      "detach from console" },
#endif
    { "hostname", 0, arg_string, &slave_str,
      "hostname of slave (if not same as hostname)", "hostname" },
    { "version", 0, arg_flag, &version_flag },
    { "help", 0, arg_flag, &help_flag }
};

static int num_args = sizeof(args) / sizeof(args[0]);

static void
usage(int status)
{
    arg_printusage(args, num_args, NULL, "master");
    exit(status);
}

int
main(int argc, char **argv)
{
    krb5_error_code ret;
    krb5_context context;
    krb5_auth_context auth_context;
    void *kadm_handle;
    kadm5_server_context *server_context;
    kadm5_config_params conf;
    int master_fd;
    krb5_ccache ccache;
    krb5_principal server;
    char **files;
    int optidx = 0;
    time_t reconnect_min;
    time_t backoff;
    time_t reconnect_max;
    time_t reconnect;
    time_t before = 0;

    const char *master;

    setprogname(argv[0]);

    if(getarg(args, num_args, argc, argv, &optidx))
	usage(1);

    if(help_flag)
	usage(0);
    if(version_flag) {
	print_version(NULL);
	exit(0);
    }

    ret = krb5_init_context(&context);
    if (ret)
	errx (1, "krb5_init_context failed: %d", ret);

    setup_signal();

    if (config_file == NULL) {
	asprintf(&config_file, "%s/kdc.conf", hdb_db_dir(context));
	if (config_file == NULL)
	    errx(1, "out of memory");
    }

    ret = krb5_prepend_config_files_default(config_file, &files);
    if (ret)
	krb5_err(context, 1, ret, "getting configuration files");

    ret = krb5_set_config_files(context, files);
    krb5_free_config_files(files);
    if (ret)
	krb5_err(context, 1, ret, "reading configuration files");

    argc -= optidx;
    argv += optidx;

    if (argc != 1)
	usage(1);

    master = argv[0];

#ifdef SUPPORT_DETACH
    if (detach_from_console)
	daemon(0, 0);
#endif
    pidfile (NULL);
    krb5_openlog (context, "ipropd-slave", &log_facility);
    krb5_set_warn_dest(context, log_facility);

    ret = krb5_kt_register(context, &hdb_kt_ops);
    if(ret)
	krb5_err(context, 1, ret, "krb5_kt_register");

    time_before_lost = parse_time (server_time_lost,  "s");
    if (time_before_lost < 0)
	krb5_errx (context, 1, "couldn't parse time: %s", server_time_lost);

    memset(&conf, 0, sizeof(conf));
    if(realm) {
	conf.mask |= KADM5_CONFIG_REALM;
	conf.realm = realm;
    }
    ret = kadm5_init_with_password_ctx (context,
					KADM5_ADMIN_SERVICE,
					NULL,
					KADM5_ADMIN_SERVICE,
					&conf, 0, 0,
					&kadm_handle);
    if (ret)
	krb5_err (context, 1, ret, "kadm5_init_with_password_ctx");

    server_context = (kadm5_server_context *)kadm_handle;

    ret = kadm5_log_init (server_context);
    if (ret)
	krb5_err (context, 1, ret, "kadm5_log_init");

    get_creds(context, keytab_str, &ccache, master);

    ret = krb5_sname_to_principal (context, master, IPROP_NAME,
				   KRB5_NT_SRV_HST, &server);
    if (ret)
	krb5_err (context, 1, ret, "krb5_sname_to_principal");

    auth_context = NULL;
    master_fd = -1;

    krb5_appdefault_time(context, config_name, NULL, "reconnect-min",
			 10, &reconnect_min);
    krb5_appdefault_time(context, config_name, NULL, "reconnect-max",
			 300, &reconnect_max);
    krb5_appdefault_time(context, config_name, NULL, "reconnect-backoff",
			 10, &backoff);
    reconnect = reconnect_min;

    while (!exit_flag) {
	time_t now, elapsed;
	int connected = FALSE;

	now = time(NULL);
	elapsed = now - before;

	if (elapsed < reconnect) {
	    time_t left = reconnect - elapsed;
	    krb5_warnx(context, "sleeping %d seconds before "
		       "retrying to connect", (int)left);
	    sleep(left);
	}
	before = now;

	master_fd = connect_to_master (context, master, port_str);
	if (master_fd < 0)
	    goto retry;

	reconnect = reconnect_min;

	if (auth_context) {
	    krb5_auth_con_free(context, auth_context);
	    auth_context = NULL;
	    krb5_cc_destroy(context, ccache);
	    get_creds(context, keytab_str, &ccache, master);
	}
	ret = krb5_sendauth (context, &auth_context, &master_fd,
			     IPROP_VERSION, NULL, server,
			     AP_OPTS_MUTUAL_REQUIRED, NULL, NULL,
			     ccache, NULL, NULL, NULL);
	if (ret) {
	    krb5_warn (context, ret, "krb5_sendauth");
	    goto retry;
	}

	krb5_warnx(context, "ipropd-slave started at version: %ld",
		   (long)server_context->log_context.version);

	ret = ihave (context, auth_context, master_fd,
		     server_context->log_context.version);
	if (ret)
	    goto retry;

	connected = TRUE;

	while (connected && !exit_flag) {
	    krb5_data out;
	    krb5_storage *sp;
	    int32_t tmp;
	    fd_set readset;
	    struct timeval to;

	    if (master_fd >= FD_SETSIZE)
		krb5_errx (context, 1, "fd too large");

	    FD_ZERO(&readset);
	    FD_SET(master_fd, &readset);

	    to.tv_sec = time_before_lost;
	    to.tv_usec = 0;

	    ret = select (master_fd + 1,
			  &readset, NULL, NULL, &to);
	    if (ret < 0) {
		if (errno == EINTR)
		    continue;
		else
		    krb5_err (context, 1, errno, "select");
	    }
	    if (ret == 0)
		krb5_errx (context, 1, "server didn't send a message "
			   "in %d seconds", time_before_lost);

	    ret = krb5_read_priv_message(context, auth_context, &master_fd, &out);
	    if (ret) {
		krb5_warn (context, ret, "krb5_read_priv_message");
		connected = FALSE;
		continue;
	    }

	    sp = krb5_storage_from_mem (out.data, out.length);
	    krb5_ret_int32 (sp, &tmp);
	    switch (tmp) {
	    case FOR_YOU :
		receive (context, sp, server_context);
		ret = ihave (context, auth_context, master_fd,
			     server_context->log_context.version);
		if (ret)
		    connected = FALSE;
		break;
	    case TELL_YOU_EVERYTHING :
		ret = receive_everything (context, master_fd, server_context,
					  auth_context);
		if (ret)
		    connected = FALSE;
		break;
	    case ARE_YOU_THERE :
		send_im_here (context, master_fd, auth_context);
		break;
	    case NOW_YOU_HAVE :
	    case I_HAVE :
	    case ONE_PRINC :
	    case I_AM_HERE :
	    default :
		krb5_warnx (context, "Ignoring command %d", tmp);
		break;
	    }
	    krb5_storage_free (sp);
	    krb5_data_free (&out);

	}
    retry:
	if (connected == FALSE)
	    krb5_warnx (context, "disconnected for server");
	if (exit_flag)
	    krb5_warnx (context, "got an exit signal");

	if (master_fd >= 0)
	    close(master_fd);

	reconnect += backoff;
	if (reconnect > reconnect_max)
	    reconnect = reconnect_max;
    }

    if(exit_flag == SIGXCPU)
	krb5_warnx(context, "%s CPU time limit exceeded", getprogname());
    else if(exit_flag == SIGINT || exit_flag == SIGTERM)
	krb5_warnx(context, "%s terminated", getprogname());
    else
	krb5_warnx(context, "%s unexpected exit reason: %ld",
		       getprogname(), (long)exit_flag);
    
    return 0;
}
