/* 
   Unix SMB/CIFS implementation.
   process incoming packets - main loop
   Copyright (C) Andrew Tridgell 1992-2003
   Copyright (C) James J Myers 2003 <myersjj@samba.org>
   Copyright (C) Stefan Metzmacher 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"
#include "lib/events/events.h"
#include "system/time.h"
#include "dlinklist.h"
#include "smbd/service_stream.h"
#include "smb_server/smb_server.h"


/*
  send an oplock break request to a client
*/
BOOL req_send_oplock_break(struct smbsrv_tcon *tcon, uint16_t fnum, uint8_t level)
{
	struct smbsrv_request *req;

	req = init_smb_request(tcon->smb_conn);

	req_setup_reply(req, 8, 0);
	
	SCVAL(req->out.hdr,HDR_COM,SMBlockingX);
	SSVAL(req->out.hdr,HDR_TID,tcon->tid);
	SSVAL(req->out.hdr,HDR_PID,0xFFFF);
	SSVAL(req->out.hdr,HDR_UID,0);
	SSVAL(req->out.hdr,HDR_MID,0xFFFF);
	SCVAL(req->out.hdr,HDR_FLG,0);
	SSVAL(req->out.hdr,HDR_FLG2,0);

	SSVAL(req->out.vwv, VWV(0), SMB_CHAIN_NONE);
	SSVAL(req->out.vwv, VWV(1), 0);
	SSVAL(req->out.vwv, VWV(2), fnum);
	SCVAL(req->out.vwv, VWV(3), LOCKING_ANDX_OPLOCK_RELEASE);
	SCVAL(req->out.vwv, VWV(3)+1, level);
	SIVAL(req->out.vwv, VWV(4), 0);
	SSVAL(req->out.vwv, VWV(6), 0);
	SSVAL(req->out.vwv, VWV(7), 0);

	req_send_reply(req);
	return True;
}


static void construct_reply(struct smbsrv_request *req);

/****************************************************************************
receive a SMB request header from the wire, forming a request_context
from the result
****************************************************************************/
static NTSTATUS receive_smb_request(struct smbsrv_connection *smb_conn)
{
	NTSTATUS status;
	ssize_t len;
	struct smbsrv_request *req;
	size_t nread;

	/* allocate the request if needed */
	if (smb_conn->partial_req == NULL) {
		req = init_smb_request(smb_conn);
		if (req == NULL) {
			return NT_STATUS_NO_MEMORY;
		}

		req->in.buffer = talloc_array(req, uint8_t, NBT_HDR_SIZE);
		if (req->in.buffer == NULL) {
			talloc_free(req);
			return NT_STATUS_NO_MEMORY;
		}
		req->in.size = 0;
		smb_conn->partial_req = req;
	}

	req = smb_conn->partial_req;

	/* read in the header */
	if (req->in.size < NBT_HDR_SIZE) {
		status = socket_recv(smb_conn->connection->socket, 
				     req->in.buffer + req->in.size,
				     NBT_HDR_SIZE - req->in.size, 
				     &nread, 0);
		if (NT_STATUS_IS_ERR(status)) {
			return status;
		}
		if (nread == 0) {
			return NT_STATUS_OK;
		}
		req->in.size += nread;

		/* when we have a full NBT header, then allocate the packet */
		if (req->in.size == NBT_HDR_SIZE) {
			len = smb_len(req->in.buffer) + NBT_HDR_SIZE;
			req->in.buffer = talloc_realloc(req, req->in.buffer, 
							uint8_t, len);
			if (req->in.buffer == NULL) {
				return NT_STATUS_NO_MEMORY;
			}
		} else {
			return NT_STATUS_OK;
		}
	}

	/* read in the main packet */
	len = smb_len(req->in.buffer) + NBT_HDR_SIZE;

	status = socket_recv(smb_conn->connection->socket, 
			     req->in.buffer + req->in.size,
			     len - req->in.size, 
			     &nread, 0);
	if (NT_STATUS_IS_ERR(status)) {
		return status;
	}
	if (nread == 0) {
		return NT_STATUS_OK;
	}

	req->in.size += nread;

	if (req->in.size != len) {
		return NT_STATUS_OK;
	}

	/* we have a full packet */
	req->request_time = timeval_current();
	req->chained_fnum = -1;
	req->in.allocated = req->in.size;
	req->in.hdr = req->in.buffer + NBT_HDR_SIZE;
	req->in.vwv = req->in.hdr + HDR_VWV;
	req->in.wct = CVAL(req->in.hdr, HDR_WCT);
	if (req->in.vwv + VWV(req->in.wct) <= req->in.buffer + req->in.size) {
		req->in.data = req->in.vwv + VWV(req->in.wct) + 2;
		req->in.data_size = SVAL(req->in.vwv, VWV(req->in.wct));

		/* the bcc length is only 16 bits, but some packets
		   (such as SMBwriteX) can be much larger than 64k. We
		   detect this by looking for a large non-chained NBT
		   packet (at least 64k bigger than what is
		   specified). If it is detected then the NBT size is
		   used instead of the bcc size */
		if (req->in.data_size + 0x10000 <= 
		    req->in.size - PTR_DIFF(req->in.data, req->in.buffer) &&
		    (req->in.wct < 1 || SVAL(req->in.vwv, VWV(0)) == SMB_CHAIN_NONE)) {
			/* its an oversized packet! fun for all the family */
			req->in.data_size = req->in.size - PTR_DIFF(req->in.data,req->in.buffer);
		}
	}

	smb_conn->partial_req = NULL;

	construct_reply(req);

	return NT_STATUS_OK;
}

/*
  These flags determine some of the permissions required to do an operation 
*/
#define AS_USER (1<<0)

/* 
   define a list of possible SMB messages and their corresponding
   functions. Any message that has a NULL function is unimplemented -
   please feel free to contribute implementations!
*/
static const struct smb_message_struct
{
	const char *name;
	void (*fn)(struct smbsrv_request *);
	int flags;
}
 smb_messages[256] = {
/* 0x00 */ { "SMBmkdir",reply_mkdir,AS_USER},
/* 0x01 */ { "SMBrmdir",reply_rmdir,AS_USER},
/* 0x02 */ { "SMBopen",reply_open,AS_USER},
/* 0x03 */ { "SMBcreate",reply_mknew,AS_USER},
/* 0x04 */ { "SMBclose",reply_close,AS_USER},
/* 0x05 */ { "SMBflush",reply_flush,AS_USER},
/* 0x06 */ { "SMBunlink",reply_unlink,AS_USER},
/* 0x07 */ { "SMBmv",reply_mv,AS_USER},
/* 0x08 */ { "SMBgetatr",reply_getatr,AS_USER},
/* 0x09 */ { "SMBsetatr",reply_setatr,AS_USER},
/* 0x0a */ { "SMBread",reply_read,AS_USER},
/* 0x0b */ { "SMBwrite",reply_write,AS_USER},
/* 0x0c */ { "SMBlock",reply_lock,AS_USER},
/* 0x0d */ { "SMBunlock",reply_unlock,AS_USER},
/* 0x0e */ { "SMBctemp",reply_ctemp,AS_USER },
/* 0x0f */ { "SMBmknew",reply_mknew,AS_USER}, 
/* 0x10 */ { "SMBchkpth",reply_chkpth,AS_USER},
/* 0x11 */ { "SMBexit",reply_exit,0},
/* 0x12 */ { "SMBlseek",reply_lseek,AS_USER},
/* 0x13 */ { "SMBlockread",reply_lockread,AS_USER},
/* 0x14 */ { "SMBwriteunlock",reply_writeunlock,AS_USER},
/* 0x15 */ { NULL, NULL, 0 },
/* 0x16 */ { NULL, NULL, 0 },
/* 0x17 */ { NULL, NULL, 0 },
/* 0x18 */ { NULL, NULL, 0 },
/* 0x19 */ { NULL, NULL, 0 },
/* 0x1a */ { "SMBreadbraw",reply_readbraw,AS_USER},
/* 0x1b */ { "SMBreadBmpx",reply_readbmpx,AS_USER},
/* 0x1c */ { "SMBreadBs",NULL,0 },
/* 0x1d */ { "SMBwritebraw",reply_writebraw,AS_USER},
/* 0x1e */ { "SMBwriteBmpx",reply_writebmpx,AS_USER},
/* 0x1f */ { "SMBwriteBs",reply_writebs,AS_USER},
/* 0x20 */ { "SMBwritec",NULL,0},
/* 0x21 */ { NULL, NULL, 0 },
/* 0x22 */ { "SMBsetattrE",reply_setattrE,AS_USER},
/* 0x23 */ { "SMBgetattrE",reply_getattrE,AS_USER},
/* 0x24 */ { "SMBlockingX",reply_lockingX,AS_USER},
/* 0x25 */ { "SMBtrans",reply_trans,AS_USER},
/* 0x26 */ { "SMBtranss",reply_transs,AS_USER},
/* 0x27 */ { "SMBioctl",reply_ioctl,0},
/* 0x28 */ { "SMBioctls",NULL,AS_USER},
/* 0x29 */ { "SMBcopy",reply_copy,AS_USER},
/* 0x2a */ { "SMBmove",NULL,AS_USER},
/* 0x2b */ { "SMBecho",reply_echo,0},
/* 0x2c */ { "SMBwriteclose",reply_writeclose,AS_USER},
/* 0x2d */ { "SMBopenX",reply_open_and_X,AS_USER},
/* 0x2e */ { "SMBreadX",reply_read_and_X,AS_USER},
/* 0x2f */ { "SMBwriteX",reply_write_and_X,AS_USER},
/* 0x30 */ { NULL, NULL, 0 },
/* 0x31 */ { NULL, NULL, 0 },
/* 0x32 */ { "SMBtrans2", reply_trans2, AS_USER},
/* 0x33 */ { "SMBtranss2", reply_transs2, AS_USER},
/* 0x34 */ { "SMBfindclose", reply_findclose,AS_USER},
/* 0x35 */ { "SMBfindnclose", reply_findnclose, AS_USER},
/* 0x36 */ { NULL, NULL, 0 },
/* 0x37 */ { NULL, NULL, 0 },
/* 0x38 */ { NULL, NULL, 0 },
/* 0x39 */ { NULL, NULL, 0 },
/* 0x3a */ { NULL, NULL, 0 },
/* 0x3b */ { NULL, NULL, 0 },
/* 0x3c */ { NULL, NULL, 0 },
/* 0x3d */ { NULL, NULL, 0 },
/* 0x3e */ { NULL, NULL, 0 },
/* 0x3f */ { NULL, NULL, 0 },
/* 0x40 */ { NULL, NULL, 0 },
/* 0x41 */ { NULL, NULL, 0 },
/* 0x42 */ { NULL, NULL, 0 },
/* 0x43 */ { NULL, NULL, 0 },
/* 0x44 */ { NULL, NULL, 0 },
/* 0x45 */ { NULL, NULL, 0 },
/* 0x46 */ { NULL, NULL, 0 },
/* 0x47 */ { NULL, NULL, 0 },
/* 0x48 */ { NULL, NULL, 0 },
/* 0x49 */ { NULL, NULL, 0 },
/* 0x4a */ { NULL, NULL, 0 },
/* 0x4b */ { NULL, NULL, 0 },
/* 0x4c */ { NULL, NULL, 0 },
/* 0x4d */ { NULL, NULL, 0 },
/* 0x4e */ { NULL, NULL, 0 },
/* 0x4f */ { NULL, NULL, 0 },
/* 0x50 */ { NULL, NULL, 0 },
/* 0x51 */ { NULL, NULL, 0 },
/* 0x52 */ { NULL, NULL, 0 },
/* 0x53 */ { NULL, NULL, 0 },
/* 0x54 */ { NULL, NULL, 0 },
/* 0x55 */ { NULL, NULL, 0 },
/* 0x56 */ { NULL, NULL, 0 },
/* 0x57 */ { NULL, NULL, 0 },
/* 0x58 */ { NULL, NULL, 0 },
/* 0x59 */ { NULL, NULL, 0 },
/* 0x5a */ { NULL, NULL, 0 },
/* 0x5b */ { NULL, NULL, 0 },
/* 0x5c */ { NULL, NULL, 0 },
/* 0x5d */ { NULL, NULL, 0 },
/* 0x5e */ { NULL, NULL, 0 },
/* 0x5f */ { NULL, NULL, 0 },
/* 0x60 */ { NULL, NULL, 0 },
/* 0x61 */ { NULL, NULL, 0 },
/* 0x62 */ { NULL, NULL, 0 },
/* 0x63 */ { NULL, NULL, 0 },
/* 0x64 */ { NULL, NULL, 0 },
/* 0x65 */ { NULL, NULL, 0 },
/* 0x66 */ { NULL, NULL, 0 },
/* 0x67 */ { NULL, NULL, 0 },
/* 0x68 */ { NULL, NULL, 0 },
/* 0x69 */ { NULL, NULL, 0 },
/* 0x6a */ { NULL, NULL, 0 },
/* 0x6b */ { NULL, NULL, 0 },
/* 0x6c */ { NULL, NULL, 0 },
/* 0x6d */ { NULL, NULL, 0 },
/* 0x6e */ { NULL, NULL, 0 },
/* 0x6f */ { NULL, NULL, 0 },
/* 0x70 */ { "SMBtcon",reply_tcon,0},
/* 0x71 */ { "SMBtdis",reply_tdis,0},
/* 0x72 */ { "SMBnegprot",reply_negprot,0},
/* 0x73 */ { "SMBsesssetupX",reply_sesssetup,0},
/* 0x74 */ { "SMBulogoffX", reply_ulogoffX, 0}, /* ulogoff doesn't give a valid TID */
/* 0x75 */ { "SMBtconX",reply_tcon_and_X,0},
/* 0x76 */ { NULL, NULL, 0 },
/* 0x77 */ { NULL, NULL, 0 },
/* 0x78 */ { NULL, NULL, 0 },
/* 0x79 */ { NULL, NULL, 0 },
/* 0x7a */ { NULL, NULL, 0 },
/* 0x7b */ { NULL, NULL, 0 },
/* 0x7c */ { NULL, NULL, 0 },
/* 0x7d */ { NULL, NULL, 0 },
/* 0x7e */ { NULL, NULL, 0 },
/* 0x7f */ { NULL, NULL, 0 },
/* 0x80 */ { "SMBdskattr",reply_dskattr,AS_USER},
/* 0x81 */ { "SMBsearch",reply_search,AS_USER},
/* 0x82 */ { "SMBffirst",reply_search,AS_USER},
/* 0x83 */ { "SMBfunique",reply_search,AS_USER},
/* 0x84 */ { "SMBfclose",reply_fclose,AS_USER},
/* 0x85 */ { NULL, NULL, 0 },
/* 0x86 */ { NULL, NULL, 0 },
/* 0x87 */ { NULL, NULL, 0 },
/* 0x88 */ { NULL, NULL, 0 },
/* 0x89 */ { NULL, NULL, 0 },
/* 0x8a */ { NULL, NULL, 0 },
/* 0x8b */ { NULL, NULL, 0 },
/* 0x8c */ { NULL, NULL, 0 },
/* 0x8d */ { NULL, NULL, 0 },
/* 0x8e */ { NULL, NULL, 0 },
/* 0x8f */ { NULL, NULL, 0 },
/* 0x90 */ { NULL, NULL, 0 },
/* 0x91 */ { NULL, NULL, 0 },
/* 0x92 */ { NULL, NULL, 0 },
/* 0x93 */ { NULL, NULL, 0 },
/* 0x94 */ { NULL, NULL, 0 },
/* 0x95 */ { NULL, NULL, 0 },
/* 0x96 */ { NULL, NULL, 0 },
/* 0x97 */ { NULL, NULL, 0 },
/* 0x98 */ { NULL, NULL, 0 },
/* 0x99 */ { NULL, NULL, 0 },
/* 0x9a */ { NULL, NULL, 0 },
/* 0x9b */ { NULL, NULL, 0 },
/* 0x9c */ { NULL, NULL, 0 },
/* 0x9d */ { NULL, NULL, 0 },
/* 0x9e */ { NULL, NULL, 0 },
/* 0x9f */ { NULL, NULL, 0 },
/* 0xa0 */ { "SMBnttrans", reply_nttrans, AS_USER},
/* 0xa1 */ { "SMBnttranss", reply_nttranss, AS_USER},
/* 0xa2 */ { "SMBntcreateX", reply_ntcreate_and_X, AS_USER},
/* 0xa3 */ { NULL, NULL, 0 },
/* 0xa4 */ { "SMBntcancel", reply_ntcancel, 0 },
/* 0xa5 */ { "SMBntrename", reply_ntrename, 0 },
/* 0xa6 */ { NULL, NULL, 0 },
/* 0xa7 */ { NULL, NULL, 0 },
/* 0xa8 */ { NULL, NULL, 0 },
/* 0xa9 */ { NULL, NULL, 0 },
/* 0xaa */ { NULL, NULL, 0 },
/* 0xab */ { NULL, NULL, 0 },
/* 0xac */ { NULL, NULL, 0 },
/* 0xad */ { NULL, NULL, 0 },
/* 0xae */ { NULL, NULL, 0 },
/* 0xaf */ { NULL, NULL, 0 },
/* 0xb0 */ { NULL, NULL, 0 },
/* 0xb1 */ { NULL, NULL, 0 },
/* 0xb2 */ { NULL, NULL, 0 },
/* 0xb3 */ { NULL, NULL, 0 },
/* 0xb4 */ { NULL, NULL, 0 },
/* 0xb5 */ { NULL, NULL, 0 },
/* 0xb6 */ { NULL, NULL, 0 },
/* 0xb7 */ { NULL, NULL, 0 },
/* 0xb8 */ { NULL, NULL, 0 },
/* 0xb9 */ { NULL, NULL, 0 },
/* 0xba */ { NULL, NULL, 0 },
/* 0xbb */ { NULL, NULL, 0 },
/* 0xbc */ { NULL, NULL, 0 },
/* 0xbd */ { NULL, NULL, 0 },
/* 0xbe */ { NULL, NULL, 0 },
/* 0xbf */ { NULL, NULL, 0 },
/* 0xc0 */ { "SMBsplopen",reply_printopen,AS_USER },
/* 0xc1 */ { "SMBsplwr",reply_printwrite,AS_USER},
/* 0xc2 */ { "SMBsplclose",reply_printclose,AS_USER},
/* 0xc3 */ { "SMBsplretq",reply_printqueue,AS_USER},
/* 0xc4 */ { NULL, NULL, 0 },
/* 0xc5 */ { NULL, NULL, 0 },
/* 0xc6 */ { NULL, NULL, 0 },
/* 0xc7 */ { NULL, NULL, 0 },
/* 0xc8 */ { NULL, NULL, 0 },
/* 0xc9 */ { NULL, NULL, 0 },
/* 0xca */ { NULL, NULL, 0 },
/* 0xcb */ { NULL, NULL, 0 },
/* 0xcc */ { NULL, NULL, 0 },
/* 0xcd */ { NULL, NULL, 0 },
/* 0xce */ { NULL, NULL, 0 },
/* 0xcf */ { NULL, NULL, 0 },
/* 0xd0 */ { "SMBsends",reply_sends,0},
/* 0xd1 */ { "SMBsendb",NULL,0},
/* 0xd2 */ { "SMBfwdname",NULL,0},
/* 0xd3 */ { "SMBcancelf",NULL,0},
/* 0xd4 */ { "SMBgetmac",NULL,0},
/* 0xd5 */ { "SMBsendstrt",reply_sendstrt,0},
/* 0xd6 */ { "SMBsendend",reply_sendend,0},
/* 0xd7 */ { "SMBsendtxt",reply_sendtxt,0},
/* 0xd8 */ { NULL, NULL, 0 },
/* 0xd9 */ { NULL, NULL, 0 },
/* 0xda */ { NULL, NULL, 0 },
/* 0xdb */ { NULL, NULL, 0 },
/* 0xdc */ { NULL, NULL, 0 },
/* 0xdd */ { NULL, NULL, 0 },
/* 0xde */ { NULL, NULL, 0 },
/* 0xdf */ { NULL, NULL, 0 },
/* 0xe0 */ { NULL, NULL, 0 },
/* 0xe1 */ { NULL, NULL, 0 },
/* 0xe2 */ { NULL, NULL, 0 },
/* 0xe3 */ { NULL, NULL, 0 },
/* 0xe4 */ { NULL, NULL, 0 },
/* 0xe5 */ { NULL, NULL, 0 },
/* 0xe6 */ { NULL, NULL, 0 },
/* 0xe7 */ { NULL, NULL, 0 },
/* 0xe8 */ { NULL, NULL, 0 },
/* 0xe9 */ { NULL, NULL, 0 },
/* 0xea */ { NULL, NULL, 0 },
/* 0xeb */ { NULL, NULL, 0 },
/* 0xec */ { NULL, NULL, 0 },
/* 0xed */ { NULL, NULL, 0 },
/* 0xee */ { NULL, NULL, 0 },
/* 0xef */ { NULL, NULL, 0 },
/* 0xf0 */ { NULL, NULL, 0 },
/* 0xf1 */ { NULL, NULL, 0 },
/* 0xf2 */ { NULL, NULL, 0 },
/* 0xf3 */ { NULL, NULL, 0 },
/* 0xf4 */ { NULL, NULL, 0 },
/* 0xf5 */ { NULL, NULL, 0 },
/* 0xf6 */ { NULL, NULL, 0 },
/* 0xf7 */ { NULL, NULL, 0 },
/* 0xf8 */ { NULL, NULL, 0 },
/* 0xf9 */ { NULL, NULL, 0 },
/* 0xfa */ { NULL, NULL, 0 },
/* 0xfb */ { NULL, NULL, 0 },
/* 0xfc */ { NULL, NULL, 0 },
/* 0xfd */ { NULL, NULL, 0 },
/* 0xfe */ { NULL, NULL, 0 },
/* 0xff */ { NULL, NULL, 0 }
};

/****************************************************************************
return a string containing the function name of a SMB command
****************************************************************************/
static const char *smb_fn_name(uint8_t type)
{
	const char *unknown_name = "SMBunknown";

	if (smb_messages[type].name == NULL)
		return unknown_name;

	return smb_messages[type].name;
}


/****************************************************************************
 Do a switch on the message type and call the specific reply function for this 
message. Unlike earlier versions of Samba the reply functions are responsible
for sending the reply themselves, rather than returning a size to this function
The reply functions may also choose to delay the processing by pushing the message
onto the message queue
****************************************************************************/
static void switch_message(int type, struct smbsrv_request *req)
{
	int flags;
	struct smbsrv_connection *smb_conn = req->smb_conn;
	uint16_t session_tag;

	type &= 0xff;

	errno = 0;

	if (smb_messages[type].fn == NULL) {
		DEBUG(0,("Unknown message type %d!\n",type));
		reply_unknown(req);
		return;
	}

	flags = smb_messages[type].flags;

	req->tcon = smbsrv_tcon_find(smb_conn, SVAL(req->in.hdr,HDR_TID));

	if (req->session == NULL) {
		/* setup the user context for this request if it
		   hasn't already been initialised (to cope with SMB
		   chaining) */

		/* In share mode security we must ignore the vuid. */
		if (lp_security() == SEC_SHARE) {
			session_tag = UID_FIELD_INVALID;
		} else {
			session_tag = SVAL(req->in.hdr,HDR_UID);
		}

		req->session = smbsrv_session_find(req->smb_conn, session_tag);
		if (req->session) {
			req->session->vuid = session_tag;
		}
	} else {
		session_tag = req->session->vuid;
	}

	DEBUG(3,("switch message %s (task_id %d)\n",smb_fn_name(type), req->smb_conn->connection->server_id));

	/* does this protocol need a valid tree connection? */
	if ((flags & AS_USER) && !req->tcon) {
		if (type == SMBntcreateX) {
			/* amazingly, the error code depends on the command */
			req_reply_error(req, NT_STATUS_DOS(ERRSRV, ERRinvnid));
		} else {
			req_reply_error(req, NT_STATUS_INVALID_HANDLE);
		}
		return;
	}

	/* see if the vuid is valid */
	if ((flags & AS_USER) && !req->session) {
		req_reply_error(req, NT_STATUS_DOS(ERRSRV, ERRbaduid));
		return;
	}

	smb_messages[type].fn(req);
}


/****************************************************************************
 Construct a reply to the incoming packet.
****************************************************************************/
static void construct_reply(struct smbsrv_request *req)
{
	uint8_t type = CVAL(req->in.hdr,HDR_COM);

	/* see if its a special NBT packet */
	if (CVAL(req->in.buffer,0) != 0) {
		reply_special(req);
		return;
	}

	/* Make sure this is an SMB packet */	
	if (memcmp(req->in.hdr,"\377SMB",4) != 0) {
		DEBUG(2,("Non-SMB packet of length %d. Terminating connection\n", 
			 req->in.size));
		smbsrv_terminate_connection(req->smb_conn, "Non-SMB packet");
		return;
	}

	if (NBT_HDR_SIZE + MIN_SMB_SIZE + 2*req->in.wct > req->in.size) {
		DEBUG(2,("Invalid SMB word count %d\n", req->in.wct));
		smbsrv_terminate_connection(req->smb_conn, "Invalid SMB packet");
		return;
	}

	if (NBT_HDR_SIZE + MIN_SMB_SIZE + 2*req->in.wct + req->in.data_size > req->in.size) {
		DEBUG(2,("Invalid SMB buffer length count %d\n", req->in.data_size));
		smbsrv_terminate_connection(req->smb_conn, "Invalid SMB packet");
		return;
	}

	req->flags = CVAL(req->in.hdr, HDR_FLG);
	req->flags2 = SVAL(req->in.hdr, HDR_FLG2);
	req->smbpid = SVAL(req->in.hdr,HDR_PID);

	if (!req_signing_check_incoming(req)) {
		req_reply_error(req, NT_STATUS_ACCESS_DENIED);
		return;
	}

	switch_message(type, req);
}


/*
  we call this when first first part of a possibly chained request has been completed
  and we need to call the 2nd part, if any
*/
void chain_reply(struct smbsrv_request *req)
{
	uint16_t chain_cmd, chain_offset;
	uint8_t *vwv, *data;
	uint16_t wct;
	uint16_t data_size;

	if (req->in.wct < 2 || req->out.wct < 2) {
		req_reply_dos_error(req, ERRSRV, ERRerror);
		return;
	}

	chain_cmd    = CVAL(req->in.vwv, VWV(0));
	chain_offset = SVAL(req->in.vwv, VWV(1));

	if (chain_cmd == SMB_CHAIN_NONE) {
		/* end of chain */
		SSVAL(req->out.vwv, VWV(0), SMB_CHAIN_NONE);
		SSVAL(req->out.vwv, VWV(1), 0);
		req_send_reply(req);
		return;
	}

	if (chain_offset + req->in.hdr >= req->in.buffer + req->in.size) {
		goto error;
	}

	wct = CVAL(req->in.hdr, chain_offset);
	vwv = req->in.hdr + chain_offset + 1;

	if (vwv + VWV(wct) + 2 > req->in.buffer + req->in.size) {
		goto error;
	}

	data_size = SVAL(vwv, VWV(wct));
	data = vwv + VWV(wct) + 2;

	if (data + data_size > req->in.buffer + req->in.size) {
		goto error;
	}

	/* all seems legit */
	req->in.vwv = vwv;
	req->in.wct = wct;
	req->in.data = data;
	req->in.data_size = data_size;
	req->in.ptr = data;

	req->chain_count++;

	SSVAL(req->out.vwv, VWV(0), chain_cmd);
	SSVAL(req->out.vwv, VWV(1), req->out.size - NBT_HDR_SIZE);

	/* the current request in the chain might have used an async reply,
	   but that doesn't mean the next element needs to */
	ZERO_STRUCTP(req->async_states);

	switch_message(chain_cmd, req);
	return;

error:
	SSVAL(req->out.vwv, VWV(0), SMB_CHAIN_NONE);
	SSVAL(req->out.vwv, VWV(1), 0);
	req_reply_dos_error(req, ERRSRV, ERRerror);
}


/*
  close the socket and shutdown a server_context
*/
void smbsrv_terminate_connection(struct smbsrv_connection *smb_conn, const char *reason)
{
	stream_terminate_connection(smb_conn->connection, reason);
}

/*
  called when a SMB socket becomes readable
*/
static void smbsrv_recv(struct stream_connection *conn, uint16_t flags)
{
	struct smbsrv_connection *smb_conn = talloc_get_type(conn->private, struct smbsrv_connection);
	NTSTATUS status;

	DEBUG(10,("smbsrv_recv\n"));

	/* our backends are designed to process one request at a time,
	   unless they deliberately mark the request as async and
	   process it later on a timer or other event. This enforces
	   that ordering. */
	if (smb_conn->processing) {
		EVENT_FD_NOT_READABLE(conn->event.fde);
		return;
	}

	smb_conn->processing = True;
	status = receive_smb_request(smb_conn);
	smb_conn->processing = False;
	if (NT_STATUS_IS_ERR(status)) {
		talloc_free(conn->event.fde);
		conn->event.fde = NULL;
		smbsrv_terminate_connection(smb_conn, nt_errstr(status));
		return;
	}

	EVENT_FD_READABLE(conn->event.fde);

	/* free up temporary memory */
	lp_talloc_free();
}

/*
  called when a SMB socket becomes writable
*/
static void smbsrv_send(struct stream_connection *conn, uint16_t flags)
{
	struct smbsrv_connection *smb_conn = talloc_get_type(conn->private, struct smbsrv_connection);

	while (smb_conn->pending_send) {
		struct smbsrv_request *req = smb_conn->pending_send;
		DATA_BLOB blob;
		NTSTATUS status;
		size_t sendlen;

		blob.data = req->out.buffer;
		blob.length = req->out.size;

		/* send as much of this request as we can */
		status = socket_send(conn->socket, &blob, &sendlen, 0);
		if (NT_STATUS_IS_ERR(status)) {
			smbsrv_terminate_connection(req->smb_conn, nt_errstr(status));
			return;
		}
		if (sendlen == 0) {
			break;
		}

		req->out.buffer += sendlen;
		req->out.size -= sendlen;

		/* is the whole request gone? */
		if (req->out.size == 0) {
			DLIST_REMOVE(smb_conn->pending_send, req);
			req_destroy(req);
		}
	}

	/* if no more requests are pending to be sent then
	   we should stop select for write */
	if (smb_conn->pending_send == NULL) {
		EVENT_FD_NOT_WRITEABLE(conn->event.fde);
	}
}

/*
  initialise a server_context from a open socket and register a event handler
  for reading from that socket
*/
static void smbsrv_accept(struct stream_connection *conn)
{
	struct smbsrv_connection *smb_conn;

	DEBUG(5,("smbsrv_accept\n"));

	smb_conn = talloc_zero(conn, struct smbsrv_connection);
	if (!smb_conn) return;

	/* now initialise a few default values associated with this smb socket */
	smb_conn->negotiate.max_send = 0xFFFF;

	/* this is the size that w2k uses, and it appears to be important for
	   good performance */
	smb_conn->negotiate.max_recv = lp_max_xmit();

	smb_conn->negotiate.zone_offset = get_time_zone(time(NULL));

	smbsrv_vuid_init(smb_conn);

	srv_init_signing(smb_conn);

	smbsrv_tcon_init(smb_conn);

	smb_conn->connection = conn;
	smb_conn->processing = False;

	conn->private = smb_conn;
}


static const struct stream_server_ops smb_stream_ops = {
	.name			= "smb",
	.accept_connection	= smbsrv_accept,
	.recv_handler		= smbsrv_recv,
	.send_handler		= smbsrv_send,
};

/*
  setup a listening socket on all the SMB ports for a particular address
*/
static NTSTATUS smb_add_socket(struct event_context *event_context,
			       const struct model_ops *model_ops,
			       const char *address)
{
	const char **ports = lp_smb_ports();
	int i;
	NTSTATUS status;

	for (i=0;ports[i];i++) {
		uint16_t port = atoi(ports[i]);
		if (port == 0) continue;
		status = stream_setup_socket(event_context, model_ops, &smb_stream_ops, 
					     "ipv4", address, &port, NULL);
		NT_STATUS_NOT_OK_RETURN(status);
	}

	return NT_STATUS_OK;
}

/*
  called on startup of the smb server service It's job is to start
  listening on all configured SMB server sockets
*/
static NTSTATUS smbsrv_init(struct event_context *event_context, const struct model_ops *model_ops)
{	
	NTSTATUS status;

	if (lp_interfaces() && lp_bind_interfaces_only()) {
		int num_interfaces = iface_count();
		int i;

		/* We have been given an interfaces line, and been 
		   told to only bind to those interfaces. Create a
		   socket per interface and bind to only these.
		*/
		for(i = 0; i < num_interfaces; i++) {
			const char *address = iface_n_ip(i);
			status = smb_add_socket(event_context, model_ops, address);
			NT_STATUS_NOT_OK_RETURN(status);
		}
	} else {
		/* Just bind to lp_socket_address() (usually 0.0.0.0) */
		status = smb_add_socket(event_context, model_ops, lp_socket_address());
		NT_STATUS_NOT_OK_RETURN(status);
	}

	return NT_STATUS_OK;
}

/* called at smbd startup - register ourselves as a server service */
NTSTATUS server_service_smb_init(void)
{
	return register_server_service("smb", smbsrv_init);
}