/* 
   Unix SMB/CIFS implementation.

   a composite API for finding a DC and its name

   Copyright (C) Volker Lendecke 2005
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2006
   
   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 "include/includes.h"
#include "lib/messaging/irpc.h"
#include "librpc/gen_ndr/ndr_irpc.h"
#include "librpc/gen_ndr/ndr_samr.h"
#include "libcli/composite/composite.h"
#include "libcli/libcli.h"

struct finddcs_state {
	struct composite_context *ctx;
	struct messaging_context *msg_ctx;

	const char *domain_name;
	struct dom_sid *domain_sid;

	struct nbtd_getdcname r;
	struct nbt_name_status node_status;

	int num_dcs;
	struct nbt_dc_name *dcs;
};

static void finddcs_name_resolved(struct composite_context *ctx);
static void finddcs_getdc_replied(struct irpc_request *ireq);
static void fallback_node_status(struct finddcs_state *state);
static void fallback_node_status_replied(struct nbt_name_request *name_req);

/* 
 * Setup and send off the a normal name resolution for the target name.
 *
 * The domain_sid parameter is optional, and is used in the subsequent getdc request.
 *
 * This will try a GetDC request, but this may not work.  It will try
 * a node status as a fallback, then return no name (but still include
 * the IP)
 */

struct composite_context *finddcs_send(TALLOC_CTX *mem_ctx,
				       const char *domain_name,
				       int name_type,
				       struct dom_sid *domain_sid,
				       const char **methods,
				       struct event_context *event_ctx,
				       struct messaging_context *msg_ctx)
{
	struct composite_context *result, *ctx;
	struct finddcs_state *state;
	struct nbt_name name;

	result = talloc(mem_ctx, struct composite_context);
	if (result == NULL) goto failed;
	result->state = COMPOSITE_STATE_IN_PROGRESS;
	result->async.fn = NULL;
	result->event_ctx = event_ctx;

	state = talloc(result, struct finddcs_state);
	if (state == NULL) goto failed;
	state->ctx = result;
	result->private_data = state;

	state->domain_name = talloc_strdup(state, domain_name);
	if (state->domain_name == NULL) goto failed;
	state->domain_sid = domain_sid;
	if (domain_sid != NULL) {
		if (talloc_reference(state, domain_sid) == NULL) {
			goto failed;
		}
	}
	state->msg_ctx = msg_ctx;

	make_nbt_name(&name, state->domain_name, name_type);
	ctx = resolve_name_send(&name, result->event_ctx,
				methods);

	if (ctx == NULL) goto failed;
	ctx->async.fn = finddcs_name_resolved;
	ctx->async.private_data = state;

	return result;

failed:
	talloc_free(result);
	return NULL;
}

/* Having got an name query answer, fire off a GetDC request, so we
 * can find the target's all-important name.  (Kerberos and some
 * netlogon operations are quite picky about names) 
 *
 * The name is a courtasy, if we don't find it, don't compleatly fail.
 *
 * However, if the nbt server is down, fall back to a node status
 * request
 */
static void finddcs_name_resolved(struct composite_context *ctx)
{
	struct finddcs_state *state =
		talloc_get_type(ctx->async.private_data, struct finddcs_state);
	struct irpc_request *ireq;
	uint32_t *nbt_servers;
	const char *address;

	state->ctx->status = resolve_name_recv(ctx, state, &address);
	if (!composite_is_ok(state->ctx)) return;

	state->num_dcs = 1;
	state->dcs = talloc_array(state, struct nbt_dc_name, state->num_dcs);
	if (composite_nomem(state->dcs, state->ctx)) return;

	state->dcs[0].address = talloc_steal(state->dcs, address);

	/* Try and find the nbt server.  We are not going to fail if
	 * we can't get the name, it will just be a disapointment.
	 * The nbt server just might not be running */
	nbt_servers = irpc_servers_byname(state->msg_ctx, "nbt_server");
	if ((nbt_servers == NULL) || (nbt_servers[0] == 0)) {
		fallback_node_status(state);
		return;
	}

	state->r.in.domainname = state->domain_name;
	state->r.in.ip_address = state->dcs[0].address;
	state->r.in.my_computername = lp_netbios_name();
	state->r.in.my_accountname = talloc_asprintf(state, "%s$",
						     lp_netbios_name());
	if (composite_nomem(state->r.in.my_accountname, state->ctx)) return;
	state->r.in.account_control = ACB_WSTRUST;
	state->r.in.domain_sid = state->domain_sid;

	ireq = irpc_call_send(state->msg_ctx, nbt_servers[0],
			      &dcerpc_table_irpc, DCERPC_NBTD_GETDCNAME,
			      &state->r, state);
	if (!ireq) {
		fallback_node_status(state);
		return;
	}

	composite_continue_irpc(state->ctx, ireq, finddcs_getdc_replied, state);
}

/* Called when the GetDC request returns */
static void finddcs_getdc_replied(struct irpc_request *ireq)
{
	struct finddcs_state *state =
		talloc_get_type(ireq->async.private, struct finddcs_state);

	state->ctx->status = irpc_call_recv(ireq);
	if (!composite_is_ok(state->ctx)) return;

	state->dcs[0].name = talloc_steal(state->dcs, state->r.out.dcname);
	composite_done(state->ctx);
}

/* The GetDC request might not be availible (such as occours when the
 * NBT server is down).  Fallback to a node status.  It is the best
 * hope we have... */
static void fallback_node_status(struct finddcs_state *state) 
{
	struct nbt_name_socket *nbtsock;
	struct nbt_name_request *name_req;

	state->node_status.in.name.name = "*";
	state->node_status.in.name.type = NBT_NAME_CLIENT;
	state->node_status.in.name.scope = NULL;
	state->node_status.in.dest_addr = state->dcs[0].address;
	state->node_status.in.timeout = 1;
	state->node_status.in.retries = 2;

	nbtsock = nbt_name_socket_init(state, state->ctx->event_ctx);
	if (composite_nomem(nbtsock, state->ctx)) return;
	
	name_req = nbt_name_status_send(nbtsock, &state->node_status);
	if (composite_nomem(name_req, state->ctx)) return;

	composite_continue_nbt(state->ctx, 
			       name_req, 
			       fallback_node_status_replied,
			       state);
}

/* We have a node status reply (or perhaps a timeout) */
static void fallback_node_status_replied(struct nbt_name_request *name_req) 
{
	struct finddcs_state *state = talloc_get_type(name_req->async.private, struct finddcs_state);
	state->ctx->status = nbt_name_status_recv(name_req, state, &state->node_status);
	if (!composite_is_ok(state->ctx)) return;

	if (state->node_status.out.status.num_names > 0) {
		state->dcs[0].name = talloc_steal(state->dcs, state->node_status.out.status.names[0].name);
		composite_done(state->ctx);
		return;
	}
	composite_error(state->ctx, NT_STATUS_NO_LOGON_SERVERS);
}

NTSTATUS finddcs_recv(struct composite_context *c, TALLOC_CTX *mem_ctx,
		      int *num_dcs, struct nbt_dc_name **dcs)
{
	NTSTATUS status = composite_wait(c);
	if (NT_STATUS_IS_OK(status)) {
		struct finddcs_state *state =
			talloc_get_type(c->private_data, struct finddcs_state);
		*num_dcs = state->num_dcs;
		*dcs = talloc_steal(mem_ctx, state->dcs);
	}
	talloc_free(c);
	return status;
}

NTSTATUS finddcs(TALLOC_CTX *mem_ctx,
		 const char *domain_name, int name_type, 
		 struct dom_sid *domain_sid,
		 const char **methods,
		 struct event_context *event_ctx,
		 struct messaging_context *msg_ctx,
		 int *num_dcs, struct nbt_dc_name **dcs)
{
	struct composite_context *c = finddcs_send(mem_ctx,
						   domain_name, name_type,
						   domain_sid, methods, 
						   event_ctx, msg_ctx);
	return finddcs_recv(c, mem_ctx, num_dcs, dcs);
}