/*
   Unix SMB/CIFS implementation.
   dump the remote SAM using rpc samsync operations

   Copyright (C) Guenther Deschner 2008.

   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "utils/net.h"

#if defined(HAVE_ADS) && defined(ENCTYPE_ARCFOUR_HMAC)

/****************************************************************
****************************************************************/

struct samsync_keytab_entry {
	const char *name;
	const char *principal;
	DATA_BLOB password;
	uint32_t kvno;
};

struct samsync_keytab_context {
	krb5_context context;
	krb5_keytab keytab;
	const char *keytab_name;
	ADS_STRUCT *ads;
	const char *dns_domain_name;
	uint8_t zero_buf[16];
	uint32_t count;
	struct samsync_keytab_entry *entries;
};

/****************************************************************
****************************************************************/

static int keytab_close(struct samsync_keytab_context *ctx)
{
	if (!ctx) {
		return 0;
	}

	if (ctx->keytab && ctx->context) {
		krb5_kt_close(ctx->context, ctx->keytab);
	}

	if (ctx->context) {
		krb5_free_context(ctx->context);
	}

	if (ctx->ads) {
		ads_destroy(&ctx->ads);
	}

	TALLOC_FREE(ctx);

	return 0;
}

/****************************************************************
****************************************************************/

static krb5_error_code keytab_init(TALLOC_CTX *mem_ctx,
				   const char *keytab_name,
				   struct samsync_keytab_context **ctx)
{
	krb5_error_code ret = 0;
	krb5_context context = NULL;
	krb5_keytab keytab = NULL;
	const char *keytab_string = NULL;

	struct samsync_keytab_context *r;

	r = TALLOC_ZERO_P(mem_ctx, struct samsync_keytab_context);
	if (!r) {
		return ENOMEM;
	}

	talloc_set_destructor(r, keytab_close);

	initialize_krb5_error_table();
	ret = krb5_init_context(&context);
	if (ret) {
		DEBUG(1,("keytab_init: could not krb5_init_context: %s\n",
			error_message(ret)));
		return ret;
	}

	ret = smb_krb5_open_keytab(context, keytab_name, true, &keytab);
	if (ret) {
		DEBUG(1,("keytab_init: smb_krb5_open_keytab failed (%s)\n",
			error_message(ret)));
		krb5_free_context(context);
		return ret;
	}

	ret = smb_krb5_keytab_name(mem_ctx, context, keytab, &keytab_string);
	if (ret) {
		krb5_kt_close(context, keytab);
		krb5_free_context(context);
		return ret;
	}

	r->context = context;
	r->keytab = keytab;
	r->keytab_name = keytab_string;

	*ctx = r;

	return 0;
}

/****************************************************************
****************************************************************/

static NTSTATUS keytab_ad_connect(TALLOC_CTX *mem_ctx,
				  const char *domain_name,
				  const char *username,
				  const char *password,
				  struct samsync_keytab_context *ctx)
{
	NTSTATUS status;
	ADS_STATUS ad_status;
	ADS_STRUCT *ads;
	struct netr_DsRGetDCNameInfo *info = NULL;
	const char *dc;

	status = dsgetdcname(mem_ctx, NULL, domain_name, NULL, NULL, 0, &info);
	if (!NT_STATUS_IS_OK(status)) {
		return status;
	}

	dc = strip_hostname(info->dc_unc);

	ads = ads_init(NULL, domain_name, dc);
	NT_STATUS_HAVE_NO_MEMORY(ads);

	if (getenv(KRB5_ENV_CCNAME) == NULL) {
		setenv(KRB5_ENV_CCNAME, "MEMORY:libnet_samsync_keytab", 1);
	}

	ads->auth.user_name = SMB_STRDUP(username);
	ads->auth.password = SMB_STRDUP(password);

	ad_status = ads_connect_user_creds(ads);
	if (!ADS_ERR_OK(ad_status)) {
		return NT_STATUS_UNSUCCESSFUL;
	}

	ctx->ads = ads;

	ctx->dns_domain_name = talloc_strdup_upper(mem_ctx, ads->config.realm);
	NT_STATUS_HAVE_NO_MEMORY(ctx->dns_domain_name);

	return NT_STATUS_OK;
}

/****************************************************************
****************************************************************/

static krb5_error_code keytab_add(struct samsync_keytab_context *ctx)
{
	krb5_error_code ret = 0;
	krb5_enctype enctypes[2] = { ENCTYPE_ARCFOUR_HMAC, 0 };
	int i;

	for (i=0; i<ctx->count; i++) {

		struct samsync_keytab_entry *entry = &ctx->entries[i];
		krb5_data password;
		krb5_kvno kvno;

		kvno = ads_get_kvno(ctx->ads, entry->name);

		password.data = (char *)entry->password.data;
		password.length = entry->password.length;

		ret = smb_krb5_kt_add_entry(ctx->context,
					    ctx->keytab,
					    kvno,
					    entry->principal,
					    enctypes,
					    password,
					    true);
		if (ret) {
			DEBUG(1,("keytab_add: Failed to add entry to keytab file\n"));
			return ret;
		}
	}

	return ret;
}

/****************************************************************
****************************************************************/

static NTSTATUS fetch_sam_entry_keytab(TALLOC_CTX *mem_ctx,
				       enum netr_SamDatabaseID database_id,
				       uint32_t rid,
				       struct netr_DELTA_USER *r,
				       NTSTATUS status,
				       struct samsync_keytab_context *ctx)
{
	uchar nt_passwd[16];
	struct samsync_keytab_entry *entry;

	if (memcmp(r->ntpassword.hash, ctx->zero_buf, 16) == 0) {
		return NT_STATUS_OK;
	}

	entry = TALLOC_ZERO_P(mem_ctx, struct samsync_keytab_entry);
	NT_STATUS_HAVE_NO_MEMORY(entry);

	sam_pwd_hash(rid, r->ntpassword.hash, nt_passwd, 0);

	entry->name = talloc_strdup(mem_ctx, r->account_name.string);
	entry->principal = talloc_asprintf(mem_ctx, "%s@%s",
					   r->account_name.string,
					   ctx->dns_domain_name);
	entry->password = data_blob_talloc(mem_ctx, nt_passwd, 16);

	NT_STATUS_HAVE_NO_MEMORY(entry->name);
	NT_STATUS_HAVE_NO_MEMORY(entry->principal);

	ADD_TO_ARRAY(mem_ctx, struct samsync_keytab_entry, *entry,
		     &ctx->entries, &ctx->count);

	return NT_STATUS_OK;
}

/****************************************************************
****************************************************************/

NTSTATUS fetch_sam_entries_keytab(TALLOC_CTX *mem_ctx,
				  enum netr_SamDatabaseID database_id,
				  struct netr_DELTA_ENUM_ARRAY *r,
				  NTSTATUS result,
				  struct samsync_context *ctx)
{
	NTSTATUS status = NT_STATUS_OK;
	krb5_error_code ret = 0;
	struct samsync_keytab_context *keytab_ctx = NULL;
	int i;

	ret = keytab_init(mem_ctx, ctx->output_filename, &keytab_ctx);
	if (ret) {
		status = krb5_to_nt_status(ret);
		goto out;
	}

	status = keytab_ad_connect(mem_ctx,
				   ctx->domain_name,
				   ctx->username,
				   ctx->password,
				   keytab_ctx);
	if (!NT_STATUS_IS_OK(status)) {
		goto out;
	}

	for (i = 0; i < r->num_deltas; i++) {

		if (r->delta_enum[i].delta_type != NETR_DELTA_USER) {
			continue;
		}

		status = fetch_sam_entry_keytab(mem_ctx, database_id,
						r->delta_enum[i].delta_id_union.rid,
						r->delta_enum[i].delta_union.user,
						result,
						keytab_ctx);
		if (!NT_STATUS_IS_OK(status)) {
			goto out;
		}
	}

	ret = keytab_add(keytab_ctx);
	if (ret) {
		status = krb5_to_nt_status(ret);
		ctx->error_message = talloc_asprintf(mem_ctx,
			"Failed to add entries to keytab %s: %s",
			keytab_ctx->keytab_name, error_message(ret));
		goto out;
	}

	ctx->result_message = talloc_asprintf(mem_ctx,
		"vampired %d accounts to keytab %s",
		keytab_ctx->count,
		keytab_ctx->keytab_name);
 out:
	TALLOC_FREE(keytab_ctx);

	return status;
}

#else

NTSTATUS fetch_sam_entries_keytab(TALLOC_CTX *mem_ctx,
				  enum netr_SamDatabaseID database_id,
				  struct netr_DELTA_ENUM_ARRAY *r,
				  NTSTATUS result,
				  struct samsync_context *ctx)
{
	return NT_STATUS_NOT_SUPPORTED;
}

#endif /* defined(HAVE_ADS) && defined(ENCTYPE_ARCFOUR_HMAC) */