/* 
   Unix SMB/CIFS implementation.

   low level socket handling for nbt requests

   Copyright (C) Andrew Tridgell 2005
   
   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"
#include "events.h"
#include "dlinklist.h"
#include "libcli/nbt/libnbt.h"

#define NBT_MAX_PACKET_SIZE 2048
#define NBT_MAX_REPLIES 1000

/*
  destroy a pending request
*/
static int nbt_name_request_destructor(void *ptr)
{
	struct nbt_name_request *req = talloc_get_type(ptr, struct nbt_name_request);
	
	if (req->state == NBT_REQUEST_SEND) {
		DLIST_REMOVE(req->nbtsock->send_queue, req);
	}
	if (req->state == NBT_REQUEST_WAIT) {
		req->nbtsock->num_pending--;
	}
	if (req->request->name_trn_id != 0) {
		idr_remove(req->nbtsock->idr, req->request->name_trn_id);
		req->request->name_trn_id = 0;
	}
	if (req->te) {
		event_remove_timed(req->nbtsock->event_ctx, req->te);
		req->te = NULL;
	}
	if (req->nbtsock->send_queue == NULL) {
		req->nbtsock->fde->flags &= ~EVENT_FD_WRITE;
	}
	if (req->nbtsock->num_pending == 0) {
		req->nbtsock->fde->flags &= ~EVENT_FD_READ;
	}
	return 0;
}


/*
  handle send events on a nbt name socket
*/
static void nbt_name_socket_send(struct nbt_name_socket *nbtsock)
{
	struct nbt_name_request *req = nbtsock->send_queue;
	TALLOC_CTX *tmp_ctx = talloc_new(req);
	NTSTATUS status;

	while ((req = nbtsock->send_queue)) {
		DATA_BLOB blob;
		size_t len;
		
		if (DEBUGLVL(10)) {
			DEBUG(10,("Sending nbt packet:\n"));
			NDR_PRINT_DEBUG(nbt_name_packet, req->request);
		}

		status = ndr_push_struct_blob(&blob, tmp_ctx, req->request, 
					      (ndr_push_flags_fn_t)
					      ndr_push_nbt_name_packet);
		if (!NT_STATUS_IS_OK(status)) goto failed;

		if (req->request->operation & NBT_FLAG_BROADCAST) {
			socket_set_option(nbtsock->sock, "SO_BROADCAST", "1");
		}

		len = blob.length;
		status = socket_sendto(nbtsock->sock, &blob, &len, 0, 
				       req->dest_addr, req->dest_port);
		if (NT_STATUS_IS_ERR(status)) goto failed;		

		if (!NT_STATUS_IS_OK(status)) {
			talloc_free(tmp_ctx);
			return;
		}

		DLIST_REMOVE(nbtsock->send_queue, req);
		req->state = NBT_REQUEST_WAIT;
		nbtsock->fde->flags |= EVENT_FD_READ;
		nbtsock->num_pending++;
	}

	nbtsock->fde->flags &= ~EVENT_FD_WRITE;
	talloc_free(tmp_ctx);
	return;

failed:
	DLIST_REMOVE(nbtsock->send_queue, req);
	nbt_name_request_destructor(req);
	req->status = status;
	req->state = NBT_REQUEST_ERROR;
	talloc_free(tmp_ctx);
	return;
}


/*
  handle recv events on a nbt name socket
*/
static void nbt_name_socket_recv(struct nbt_name_socket *nbtsock)
{
	TALLOC_CTX *tmp_ctx = talloc_new(nbtsock);
	NTSTATUS status;
	const char *src_addr;
	int src_port;
	DATA_BLOB blob;
	size_t nread;
	struct nbt_name_packet *packet;
	struct nbt_name_request *req;

	blob = data_blob_talloc(tmp_ctx, NULL, NBT_MAX_PACKET_SIZE);
	if (blob.data == NULL) {
		talloc_free(tmp_ctx);
		return;
	}

	status = socket_recvfrom(nbtsock->sock, blob.data, blob.length, &nread, 0,
				 &src_addr, &src_port);
	if (!NT_STATUS_IS_OK(status)) {
		talloc_free(tmp_ctx);
		return;
	}
	talloc_steal(tmp_ctx, src_addr);

	packet = talloc(tmp_ctx, struct nbt_name_packet);
	if (packet == NULL) {
		talloc_free(tmp_ctx);
		return;
	}

	status = ndr_pull_struct_blob(&blob, packet, packet, 
				      (ndr_pull_flags_fn_t)ndr_pull_nbt_name_packet);
	if (!NT_STATUS_IS_OK(status)) {
		DEBUG(2,("Failed to parse incoming NBT name packet - %s\n",
			 nt_errstr(status)));
		talloc_free(tmp_ctx);
		return;
	}

	if (DEBUGLVL(10)) {
		DEBUG(10,("Received nbt packet:\n"));
		NDR_PRINT_DEBUG(nbt_name_packet, packet);
	}

	if (!(packet->operation & NBT_FLAG_REPLY)) {
		talloc_free(tmp_ctx);
		return;
	}

	/* find the matching request */
	req = idr_find(nbtsock->idr, packet->name_trn_id);
	if (req == NULL) {
		DEBUG(2,("Failed to match request for incoming name packet id 0x%04x\n",
			 packet->name_trn_id));
		talloc_free(tmp_ctx);
		return;
	}

	req->replies = talloc_realloc(req, req->replies, struct nbt_name_reply, req->num_replies+1);
	if (req->replies == NULL) {
		nbt_name_request_destructor(req);
		req->state = NBT_REQUEST_DONE;
		req->status = NT_STATUS_NO_MEMORY;
		talloc_free(tmp_ctx);
		return;
	}

	req->replies[req->num_replies].reply_addr = talloc_steal(req, src_addr);
	req->replies[req->num_replies].reply_port = src_port;
	req->replies[req->num_replies].packet = talloc_steal(req, packet);
	req->num_replies++;

	/* if we don't want multiple replies then we are done */
	if (!req->allow_multiple_replies ||
	    req->num_replies == NBT_MAX_REPLIES) {
		nbt_name_request_destructor(req);
		req->state = NBT_REQUEST_DONE;
		req->status = NT_STATUS_OK;
	}

	talloc_free(tmp_ctx);
}

/*
  handle fd events on a nbt_name_socket
*/
static void nbt_name_socket_handler(struct event_context *ev, struct fd_event *fde,
				    struct timeval t, uint16_t flags)
{
	struct nbt_name_socket *nbtsock = talloc_get_type(fde->private, 
							  struct nbt_name_socket);
	if (flags & EVENT_FD_WRITE) {
		nbt_name_socket_send(nbtsock);
	} else if (flags & EVENT_FD_READ) {
		nbt_name_socket_recv(nbtsock);
	}
}


/*
  initialise a nbt_name_socket. The event_ctx is optional, if provided
  then operations will use that event context
*/
struct nbt_name_socket *nbt_name_socket_init(TALLOC_CTX *mem_ctx, 
					     struct event_context *event_ctx)
{
	struct nbt_name_socket *nbtsock;
	NTSTATUS status;
	struct fd_event fde;

	nbtsock = talloc(mem_ctx, struct nbt_name_socket);
	if (nbtsock == NULL) goto failed;

	if (event_ctx == NULL) {
		nbtsock->event_ctx = event_context_init(nbtsock);
	} else {
		nbtsock->event_ctx = talloc_reference(nbtsock, event_ctx);
	}
	if (nbtsock->event_ctx == NULL) goto failed;

	status = socket_create("ip", SOCKET_TYPE_DGRAM, &nbtsock->sock, 0);
	if (!NT_STATUS_IS_OK(status)) goto failed;

	talloc_steal(nbtsock, nbtsock->sock);

	nbtsock->idr = idr_init(nbtsock);
	if (nbtsock->idr == NULL) goto failed;

	nbtsock->send_queue = NULL;
	nbtsock->num_pending = 0;

	fde.fd = socket_get_fd(nbtsock->sock);
	fde.flags = 0;
	fde.handler = nbt_name_socket_handler;
	fde.private = nbtsock;
	nbtsock->fde = event_add_fd(nbtsock->event_ctx, &fde);

	return nbtsock;

failed:
	talloc_free(nbtsock);
	return NULL;
}

/*
  handle a request timeout
*/
static void nbt_name_socket_timeout(struct event_context *ev, struct timed_event *te,
				    struct timeval t)
{
	struct nbt_name_request *req = talloc_get_type(te->private, 
						       struct nbt_name_request);
	nbt_name_request_destructor(req);
	req->state = NBT_REQUEST_TIMEOUT;
	req->status = NT_STATUS_IO_TIMEOUT;
}

/*
  send off a nbt name request
*/
struct nbt_name_request *nbt_name_request_send(struct nbt_name_socket *nbtsock, 
					       const char *dest_addr, int dest_port,
					       struct nbt_name_packet *request,
					       struct timeval timeout,
					       BOOL allow_multiple_replies)
{
	struct nbt_name_request *req;
	struct timed_event te;
	int id;

	req = talloc_zero(nbtsock, struct nbt_name_request);
	if (req == NULL) goto failed;

	req->nbtsock = nbtsock;
	req->dest_addr = dest_addr;
	req->dest_port = dest_port;
	req->request = talloc_reference(req, request);
	req->allow_multiple_replies = allow_multiple_replies;
	req->state = NBT_REQUEST_SEND;

	if (req->request->name_trn_id == 0) {
		req->request->name_trn_id = random() % UINT16_MAX;
	}

	id = idr_get_new_above(req->nbtsock->idr, req, 
			       req->request->name_trn_id, UINT16_MAX);
	if (id == -1) {
		id = idr_get_new_above(req->nbtsock->idr, req, 1+(random()%10000),
				       UINT16_MAX);
	}
	if (id == -1) goto failed;

	te.next_event = timeout;
	te.handler = nbt_name_socket_timeout;
	te.private = req;
	req->te = event_add_timed(nbtsock->event_ctx, &te);
	
	talloc_set_destructor(req, nbt_name_request_destructor);	

	DLIST_ADD_END(nbtsock->send_queue, req, struct nbt_name_request *);

	nbtsock->fde->flags |= EVENT_FD_WRITE;

	return req;

failed:
	talloc_free(req);
	return NULL;
}

/*
  wait for a nbt request to complete
*/
NTSTATUS nbt_name_request_recv(struct nbt_name_request *req)
{
	if (!req) return NT_STATUS_NO_MEMORY;

	while (req->state < NBT_REQUEST_DONE) {
		if (event_loop_once(req->nbtsock->event_ctx) != 0) {
			req->state = NBT_REQUEST_ERROR;
			req->status = NT_STATUS_UNEXPECTED_NETWORK_ERROR;
		}
	}
	return req->status;
}