/*
   Unix SMB/CIFS implementation.
   kerberos keytab utility library
   Copyright (C) Andrew Tridgell 2001
   Copyright (C) Remus Koos 2001
   Copyright (C) Luke Howard 2003
   Copyright (C) Jim McDonough (jmcd@us.ibm.com) 2003
   Copyright (C) Guenther Deschner 2003
   Copyright (C) Rakesh Patel 2004
   Copyright (C) Dan Perry 2004
   Copyright (C) Jeremy Allison 2004

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

#ifdef HAVE_KRB5

/**********************************************************************
 Adds a single service principal, i.e. 'host' to the system keytab
***********************************************************************/

int ads_keytab_add_entry(ADS_STRUCT *ads, const char *srvPrinc)
{
	krb5_error_code ret = 0;
	krb5_context context = NULL;
	krb5_keytab keytab = NULL;
	krb5_kt_cursor cursor;
	krb5_keytab_entry kt_entry;
	krb5_principal princ = NULL;
	krb5_data password;
	krb5_enctype *enctypes = NULL;
	krb5_kvno kvno;

	char *principal = NULL;
	char *princ_s = NULL;
	char *password_s = NULL;
#ifndef MAX_KEYTAB_NAME_LEN
#define MAX_KEYTAB_NAME_LEN 1100
#endif
	char keytab_name[MAX_KEYTAB_NAME_LEN];          /* This MAX_NAME_LEN is a constant defined in krb5.h */
	fstring my_fqdn;
	int i;
	char *ktprinc = NULL;

	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	initialize_krb5_error_table();
	ret = krb5_init_context(&context);
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: could not krb5_init_context: %s\n",error_message(ret)));
		return -1;
	}
#ifdef HAVE_WRFILE_KEYTAB       /* MIT */
	keytab_name[0] = 'W';
	keytab_name[1] = 'R';
	ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
#else                           /* Heimdal */
	ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
#endif
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: krb5_kt_default_name failed (%s)\n", error_message(ret)));
		goto out;
	}
	DEBUG(2,("ads_keytab_add_entry: Using default system keytab: %s\n", (char *) &keytab_name));
	ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: krb5_kt_resolve failed (%s)\n", error_message(ret)));
		goto out;
	}

	/* retrieve the password */
	if (!secrets_init()) {
		DEBUG(1,("ads_keytab_add_entry: secrets_init failed\n"));
		ret = -1;
		goto out;
	}
	password_s = secrets_fetch_machine_password(lp_workgroup(), NULL, NULL);
	if (!password_s) {
		DEBUG(1,("ads_keytab_add_entry: failed to fetch machine password\n"));
		ret = -1;
		goto out;
	}
	password.data = password_s;
	password.length = strlen(password_s);

	/* Construct our principal */
	name_to_fqdn(my_fqdn, global_myname());
	strlower_m(my_fqdn);

	if (strchr_m(srvPrinc, '@')) {
		/* It's a fully-named principal. */
		asprintf(&princ_s, "%s", srvPrinc);
	} else if (srvPrinc[strlen(srvPrinc)-1] == '$') {
		/* It's the machine account, as used by smbclient clients. */
		asprintf(&princ_s, "%s@%s", srvPrinc, lp_realm());
	} else {
		/* It's a normal service principal.  Add the SPN now so that we
		 * can obtain credentials for it and double-check the salt value
		 * used to generate the service's keys. */
		asprintf(&princ_s, "%s/%s@%s", srvPrinc, my_fqdn, lp_realm());
		/* Update the directory with the SPN */
		DEBUG(3,("ads_keytab_add_entry: Attempting to add/update '%s'\n", princ_s));
		if (!ADS_ERR_OK(ads_add_service_principal_name(ads, global_myname(), srvPrinc))) {
			DEBUG(1,("ads_keytab_add_entry: ads_add_service_principal_name failed.\n"));
			goto out;
		}
	}

	ret = get_kerberos_allowed_etypes(context,&enctypes);
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: get_kerberos_allowed_etypes failed (%s)\n",error_message(ret)));
		goto out;
	}

	/* Guess at how the KDC is salting keys for this principal. */
	kerberos_derive_salting_principal(princ_s);

	ret = krb5_parse_name(context, princ_s, &princ);
	if (ret) {
		DEBUG(1,("ads_keytab_add_entry: krb5_parse_name(%s) failed (%s)\n", princ_s, error_message(ret)));
		goto out;
	}

	kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
	if (kvno == -1) {       /* -1 indicates failure, everything else is OK */
		DEBUG(1,("ads_keytab_add_entry: ads_get_kvno failed to determine the system's kvno.\n"));
		ret = -1;
		goto out;
	}

	/* Seek and delete old keytab entries */
	ret = krb5_kt_start_seq_get(context, keytab, &cursor);
	if (ret != KRB5_KT_END && ret != ENOENT ) {
		DEBUG(3,("ads_keytab_add_entry: Will try to delete old keytab entries\n"));
		while(!krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) {
			BOOL compare_ok = False;

			ret = krb5_unparse_name(context, kt_entry.principal, &ktprinc);
			if (ret) {
				DEBUG(1,("ads_keytab_add_entry: krb5_unparse_name failed (%s)\n", error_message(ret)));
				goto out;
			}

			/*---------------------------------------------------------------------------
			 * Save the entries with kvno - 1.   This is what microsoft does
			 * to allow people with existing sessions that have kvno - 1 to still
			 * work.   Otherwise, when the password for the machine changes, all
			 * kerberizied sessions will 'break' until either the client reboots or
			 * the client's session key expires and they get a new session ticket
			 * with the new kvno.
			 */

#ifdef HAVE_KRB5_KT_COMPARE
			compare_ok = ((krb5_kt_compare(context, &kt_entry, princ, 0, 0) == True) && (kt_entry.vno != kvno - 1));
#else
			compare_ok = ((strcmp(ktprinc, princ_s) == 0) && (kt_entry.vno != kvno - 1));
#endif
			krb5_free_unparsed_name(context, ktprinc);
			ktprinc = NULL;

			if (compare_ok) {
				DEBUG(3,("ads_keytab_add_entry: Found old entry for principal: %s (kvno %d) - trying to remove it.\n",
					princ_s, kt_entry.vno));
				ret = krb5_kt_end_seq_get(context, keytab, &cursor);
				ZERO_STRUCT(cursor);
				if (ret) {
					DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get() failed (%s)\n",
						error_message(ret)));
					goto out;
				}
				ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
				if (ret) {
					DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
						error_message(ret)));
					goto out;
				}
				ret = krb5_kt_start_seq_get(context, keytab, &cursor);
				if (ret) {
					DEBUG(1,("ads_keytab_add_entry: krb5_kt_start_seq failed (%s)\n",
						error_message(ret)));
					goto out;
				}
				ret = smb_krb5_kt_free_entry(context, &kt_entry);
				ZERO_STRUCT(kt_entry);
				if (ret) {
					DEBUG(1,("ads_keytab_add_entry: krb5_kt_remove_entry failed (%s)\n",
						error_message(ret)));
					goto out;
				}
				continue;
			}

			/* Not a match, just free this entry and continue. */
			ret = smb_krb5_kt_free_entry(context, &kt_entry);
			ZERO_STRUCT(kt_entry);
			if (ret) {
				DEBUG(1,("ads_keytab_add_entry: smb_krb5_kt_free_entry failed (%s)\n", error_message(ret)));
				goto out;
			}
		}

		ret = krb5_kt_end_seq_get(context, keytab, &cursor);
		ZERO_STRUCT(cursor);
		if (ret) {
			DEBUG(1,("ads_keytab_add_entry: krb5_kt_end_seq_get failed (%s)\n",error_message(ret)));
			goto out;
		}
	}

	/* Ensure we don't double free. */
	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	/* If we get here, we have deleted all the old entries with kvno's not equal to the current kvno-1. */

	/* Now add keytab entries for all encryption types */
	for (i = 0; enctypes[i]; i++) {
		krb5_keyblock *keyp;

#if !defined(HAVE_KRB5_KEYTAB_ENTRY_KEY) && !defined(HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK)
#error krb5_keytab_entry has no key or keyblock member
#endif
#ifdef HAVE_KRB5_KEYTAB_ENTRY_KEY               /* MIT */
		keyp = &kt_entry.key;
#endif
#ifdef HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK          /* Heimdal */
		keyp = &kt_entry.keyblock;
#endif
		if (create_kerberos_key_from_string(context, princ, &password, keyp, enctypes[i])) {
			continue;
		}

		kt_entry.principal = princ;
		kt_entry.vno       = kvno;

		DEBUG(3,("ads_keytab_add_entry: adding keytab entry for (%s) with encryption type (%d) and version (%d)\n",
			princ_s, enctypes[i], kt_entry.vno));
		ret = krb5_kt_add_entry(context, keytab, &kt_entry);
		krb5_free_keyblock_contents(context, keyp);
		ZERO_STRUCT(kt_entry);
		if (ret) {
			DEBUG(1,("ads_keytab_add_entry: adding entry to keytab failed (%s)\n", error_message(ret)));
			goto out;
		}
	}

	krb5_kt_close(context, keytab);
	keytab = NULL; /* Done with keytab now. No double free. */

out:

	SAFE_FREE(principal);
	SAFE_FREE(password_s);
	SAFE_FREE(princ_s);

	{
		krb5_keytab_entry zero_kt_entry;
		ZERO_STRUCT(zero_kt_entry);
		if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
			smb_krb5_kt_free_entry(context, &kt_entry);
		}
	}
	if (princ) {
		krb5_free_principal(context, princ);
	}
	if (enctypes) {
		free_kerberos_etypes(context, enctypes);
	}

	{
		krb5_kt_cursor zero_csr;
		ZERO_STRUCT(zero_csr);
		if ((memcmp(&cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) {
			krb5_kt_end_seq_get(context, keytab, &cursor);	
		}
	}
	if (keytab) {
		krb5_kt_close(context, keytab);
	}
	if (context) {
		krb5_free_context(context);
	}
	return (int)ret;
}

/**********************************************************************
 Flushes all entries from the system keytab.
***********************************************************************/

int ads_keytab_flush(ADS_STRUCT *ads)
{
	krb5_error_code ret = 0;
	krb5_context context = NULL;
	krb5_keytab keytab = NULL;
	krb5_kt_cursor cursor;
	krb5_keytab_entry kt_entry;
	krb5_kvno kvno;
	char keytab_name[MAX_KEYTAB_NAME_LEN];

	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	initialize_krb5_error_table();
	ret = krb5_init_context(&context);
	if (ret) {
		DEBUG(1,("ads_keytab_flush: could not krb5_init_context: %s\n",error_message(ret)));
		return ret;
	}
#ifdef HAVE_WRFILE_KEYTAB
	keytab_name[0] = 'W';
	keytab_name[1] = 'R';
	ret = krb5_kt_default_name(context, (char *) &keytab_name[2], MAX_KEYTAB_NAME_LEN - 4);
#else
	ret = krb5_kt_default_name(context, (char *) &keytab_name[0], MAX_KEYTAB_NAME_LEN - 2);
#endif
	if (ret) {
		DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
		goto out;
	}
	DEBUG(3,("ads_keytab_flush: Using default keytab: %s\n", (char *) &keytab_name));
	ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
	if (ret) {
		DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
		goto out;
	}
	ret = krb5_kt_resolve(context, (char *) &keytab_name, &keytab);
	if (ret) {
		DEBUG(1,("ads_keytab_flush: krb5_kt_default failed (%s)\n", error_message(ret)));
		goto out;
	}

	kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
	if (kvno == -1) {       /* -1 indicates a failure */
		DEBUG(1,("ads_keytab_flush: Error determining the system's kvno.\n"));
		goto out;
	}

	ret = krb5_kt_start_seq_get(context, keytab, &cursor);
	if (ret != KRB5_KT_END && ret != ENOENT) {
		while (!krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) {
			ret = krb5_kt_end_seq_get(context, keytab, &cursor);
			ZERO_STRUCT(cursor);
			if (ret) {
				DEBUG(1,("ads_keytab_flush: krb5_kt_end_seq_get() failed (%s)\n",error_message(ret)));
				goto out;
			}
			ret = krb5_kt_remove_entry(context, keytab, &kt_entry);
			if (ret) {
				DEBUG(1,("ads_keytab_flush: krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
				goto out;
			}
			ret = krb5_kt_start_seq_get(context, keytab, &cursor);
			if (ret) {
				DEBUG(1,("ads_keytab_flush: krb5_kt_start_seq failed (%s)\n",error_message(ret)));
				goto out;
			}
			ret = smb_krb5_kt_free_entry(context, &kt_entry);
			ZERO_STRUCT(kt_entry);
			if (ret) {
				DEBUG(1,("ads_keytab_flush: krb5_kt_remove_entry failed (%s)\n",error_message(ret)));
				goto out;
			}
		}
	}

	/* Ensure we don't double free. */
	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	if (!ADS_ERR_OK(ads_clear_service_principal_names(ads, global_myname()))) {
		DEBUG(1,("ads_keytab_flush: Error while clearing service principal listings in LDAP.\n"));
		goto out;
	}

out:

	{
		krb5_keytab_entry zero_kt_entry;
		ZERO_STRUCT(zero_kt_entry);
		if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
			smb_krb5_kt_free_entry(context, &kt_entry);
		}
	}
	{
		krb5_kt_cursor zero_csr;
		ZERO_STRUCT(zero_csr);
		if ((memcmp(&cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) {
			krb5_kt_end_seq_get(context, keytab, &cursor);	
		}
	}
	if (keytab) {
		krb5_kt_close(context, keytab);
	}
	if (context) {
		krb5_free_context(context);
	}
	return ret;
}

/**********************************************************************
 Adds all the required service principals to the system keytab.
***********************************************************************/

int ads_keytab_create_default(ADS_STRUCT *ads)
{
	krb5_error_code ret = 0;
	krb5_context context = NULL;
	krb5_keytab keytab = NULL;
	krb5_kt_cursor cursor;
	krb5_keytab_entry kt_entry;
	krb5_kvno kvno;
	fstring my_fqdn, my_Fqdn, my_name, my_NAME;
	char *p_fqdn;
	int i, found = 0;
	char **oldEntries = NULL, *princ_s[18];;

	ret = ads_keytab_add_entry(ads, "host");
	if (ret) {
		DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding 'host'.\n"));
		return ret;
	}
	ret = ads_keytab_add_entry(ads, "cifs");
	if (ret) {
		DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding 'cifs'.\n"));
		return ret;
	}

	fstrcpy(my_name, global_myname());
	strlower_m(my_name);

	fstrcpy(my_NAME, global_myname());
	strupper_m(my_NAME);

	my_fqdn[0] = '\0';
	name_to_fqdn(my_fqdn, global_myname());
	strlower_m(my_fqdn);

	p_fqdn = strchr_m(my_fqdn, '.');
	fstrcpy(my_Fqdn, my_NAME);
	if (p_fqdn) {
		fstrcat(my_Fqdn, p_fqdn);
	}

	asprintf(&princ_s[0], "%s$@%s", my_name, lp_realm());
	asprintf(&princ_s[1], "%s$@%s", my_NAME, lp_realm());
	asprintf(&princ_s[2], "host/%s@%s", my_name, lp_realm());
	asprintf(&princ_s[3], "host/%s@%s", my_NAME, lp_realm());
	asprintf(&princ_s[4], "host/%s@%s", my_fqdn, lp_realm());
	asprintf(&princ_s[5], "host/%s@%s", my_Fqdn, lp_realm());
	asprintf(&princ_s[6], "HOST/%s@%s", my_name, lp_realm());
	asprintf(&princ_s[7], "HOST/%s@%s", my_NAME, lp_realm());
	asprintf(&princ_s[8], "HOST/%s@%s", my_fqdn, lp_realm());
	asprintf(&princ_s[9], "HOST/%s@%s", my_Fqdn, lp_realm());
	asprintf(&princ_s[10], "cifs/%s@%s", my_name, lp_realm());
	asprintf(&princ_s[11], "cifs/%s@%s", my_NAME, lp_realm());
	asprintf(&princ_s[12], "cifs/%s@%s", my_fqdn, lp_realm());
	asprintf(&princ_s[13], "cifs/%s@%s", my_Fqdn, lp_realm());
	asprintf(&princ_s[14], "CIFS/%s@%s", my_name, lp_realm());
	asprintf(&princ_s[15], "CIFS/%s@%s", my_NAME, lp_realm());
	asprintf(&princ_s[16], "CIFS/%s@%s", my_fqdn, lp_realm());
	asprintf(&princ_s[17], "CIFS/%s@%s", my_Fqdn, lp_realm());

	for (i = 0; i < sizeof(princ_s) / sizeof(princ_s[0]); i++) {
		if (princ_s[i] != NULL) {
			ret = ads_keytab_add_entry(ads, princ_s[i]);
			if (ret != 0) {
				DEBUG(1,("ads_keytab_create_default: ads_keytab_add_entry failed while adding '%s'.\n", princ_s[i]));
			}
			SAFE_FREE(princ_s[i]);
		}
	}

	kvno = (krb5_kvno) ads_get_kvno(ads, global_myname());
	if (kvno == -1) {
		DEBUG(1,("ads_keytab_create_default: ads_get_kvno failed to determine the system's kvno.\n"));
		return -1;
	}

	DEBUG(3,("ads_keytab_create_default: Searching for keytab entries to preserve and update.\n"));
	/* Now loop through the keytab and update any other existing entries... */

	ZERO_STRUCT(kt_entry);
	ZERO_STRUCT(cursor);

	initialize_krb5_error_table();
	ret = krb5_init_context(&context);
	if (ret) {
		DEBUG(1,("ads_keytab_create_default: could not krb5_init_context: %s\n",error_message(ret)));
		return ret;
	}
	ret = krb5_kt_default(context, &keytab);
	if (ret) {
		DEBUG(1,("ads_keytab_create_default: krb5_kt_default failed (%s)\n",error_message(ret)));
		goto done;
	}

	ret = krb5_kt_start_seq_get(context, keytab, &cursor);
	if (ret != KRB5_KT_END && ret != ENOENT ) {
		while ((ret = krb5_kt_next_entry(context, keytab, &kt_entry, &cursor)) == 0) {
			smb_krb5_kt_free_entry(context, &kt_entry);
			ZERO_STRUCT(kt_entry);
			found++;
		}
	}
	krb5_kt_end_seq_get(context, keytab, &cursor);
	ZERO_STRUCT(cursor);

	/*
	 * Hmmm. There is no "rewind" function for the keytab. This means we have a race condition
	 * where someone else could add entries after we've counted them. Re-open asap to minimise
	 * the race. JRA.
	 */
	
	DEBUG(3, ("ads_keytab_create_default: Found %d entries in the keytab.\n", found));
	if (!found) {
		goto done;
	}
	oldEntries = (char **) malloc(found * sizeof(char *));
	if (!oldEntries) {
		DEBUG(1,("ads_keytab_create_default: Failed to allocate space to store the old keytab entries (malloc failed?).\n"));
		ret = -1;
		goto done;
	}
	memset(oldEntries, '\0', found * sizeof(char *));

	ret = krb5_kt_start_seq_get(context, keytab, &cursor);
	if (ret != KRB5_KT_END && ret != ENOENT ) {
		while (krb5_kt_next_entry(context, keytab, &kt_entry, &cursor) == 0) {
			if (kt_entry.vno != kvno) {
				char *ktprinc = NULL;
				char *p;

				/* This returns a malloc'ed string in ktprinc. */
				ret = krb5_unparse_name(context, kt_entry.principal, &ktprinc);
				if (ret) {
					DEBUG(1,("krb5_unparse_name failed (%s)\n", error_message(ret)));
					goto done;
				}
				/*
				 * From looking at the krb5 source they don't seem to take locale
				 * or mb strings into account. Maybe this is because they assume utf8 ?
				 * In this case we may need to convert from utf8 to mb charset here ? JRA.
				 */
				p = strchr_m(ktprinc, '@');
				if (p) {
					*p = '\0';
				}

				p = strchr_m(ktprinc, '/');
				if (p) {
					*p = '\0';
				}
				for (i = 0; i < found; i++) {
					if (!oldEntries[i]) {
						oldEntries[i] = ktprinc;
						break;
					}
					if (!strcmp(oldEntries[i], ktprinc)) {
						krb5_free_unparsed_name(context, ktprinc);
						break;
					}
				}
				if (i == found) {
					krb5_free_unparsed_name(context, ktprinc);
				}
			}
			smb_krb5_kt_free_entry(context, &kt_entry);
			ZERO_STRUCT(kt_entry);
		}
		ret = 0;
		for (i = 0; oldEntries[i]; i++) {
			ret |= ads_keytab_add_entry(ads, oldEntries[i]);
			krb5_free_unparsed_name(context, oldEntries[i]);
		}
		krb5_kt_end_seq_get(context, keytab, &cursor);
	}
	ZERO_STRUCT(cursor);

done:

	SAFE_FREE(oldEntries);

	{
		krb5_keytab_entry zero_kt_entry;
		ZERO_STRUCT(zero_kt_entry);
		if (memcmp(&zero_kt_entry, &kt_entry, sizeof(krb5_keytab_entry))) {
			smb_krb5_kt_free_entry(context, &kt_entry);
		}
	}
	{
		krb5_kt_cursor zero_csr;
		ZERO_STRUCT(zero_csr);
		if ((memcmp(&cursor, &zero_csr, sizeof(krb5_kt_cursor)) != 0) && keytab) {
			krb5_kt_end_seq_get(context, keytab, &cursor);	
		}
	}
	if (keytab) {
		krb5_kt_close(context, keytab);
	}
	if (context) {
		krb5_free_context(context);
	}
	return ret;
}
#endif /* HAVE_KRB5 */