receive.c

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/* 0xfe */ { NULL, NULL, 0 },
/* 0xff */ { NULL, NULL, 0 }
};

/****************************************************************************
receive a SMB request header from the wire, forming a request_context
from the result
****************************************************************************/
NTSTATUS smbsrv_recv_smb_request(void *private, DATA_BLOB blob)
{
	struct smbsrv_connection *smb_conn = talloc_get_type(private, struct smbsrv_connection);
	struct smbsrv_request *req;
	struct timeval cur_time = timeval_current();
	uint8_t command;

	smb_conn->statistics.last_request_time = cur_time;

	/* see if its a special NBT packet */
	if (CVAL(blob.data, 0) != 0) {
		req = smbsrv_init_request(smb_conn);
		NT_STATUS_HAVE_NO_MEMORY(req);

		ZERO_STRUCT(req->in);

		req->in.buffer = talloc_steal(req, blob.data);
		req->in.size = blob.length;
		req->request_time = cur_time;

		smbsrv_reply_special(req);
		return NT_STATUS_OK;
	}

	if ((NBT_HDR_SIZE + MIN_SMB_SIZE) > blob.length) {
		DEBUG(2,("Invalid SMB packet: length %ld\n", (long)blob.length));
		smbsrv_terminate_connection(smb_conn, "Invalid SMB packet");
		return NT_STATUS_OK;
	}

	/* Make sure this is an SMB packet */
	if (IVAL(blob.data, NBT_HDR_SIZE) != SMB_MAGIC) {
		DEBUG(2,("Non-SMB packet of length %ld. Terminating connection\n",
			 (long)blob.length));
		smbsrv_terminate_connection(smb_conn, "Non-SMB packet");
		return NT_STATUS_OK;
	}

	req = smbsrv_init_request(smb_conn);
	NT_STATUS_HAVE_NO_MEMORY(req);

	req->in.buffer = talloc_steal(req, blob.data);
	req->in.size = blob.length;
	req->request_time = cur_time;
	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);

	command = CVAL(req->in.hdr, HDR_COM);

	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) &&
			( message_flags(command) & LARGE_REQUEST) &&
			( !(message_flags(command) & AND_X) ||
		      (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);
		}
	}

	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 NT_STATUS_OK;
	}
 
	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", 
			 (int)req->in.data_size));
		smbsrv_terminate_connection(req->smb_conn, "Invalid SMB packet");
		return NT_STATUS_OK;
	}

	req->flags2	= SVAL(req->in.hdr, HDR_FLG2);

	/* fix the bufinfo */
	smbsrv_setup_bufinfo(req);

	if (!smbsrv_signing_check_incoming(req)) {
		smbsrv_send_error(req, NT_STATUS_ACCESS_DENIED);
		return NT_STATUS_OK;
	}

	command = CVAL(req->in.hdr, HDR_COM);
	switch_message(command, req);
	return NT_STATUS_OK;
}

/****************************************************************************
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;
	NTSTATUS status;

	type &= 0xff;

	errno = 0;

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

	flags = smb_messages[type].flags;

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

	if (!req->session) {
		/* 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 (smb_conn->config.security == SEC_SHARE) {
			if (req->tcon) {
				req->session = req->tcon->sec_share.session;
			}
 		} else {
			req->session = smbsrv_session_find(req->smb_conn, SVAL(req->in.hdr,HDR_UID), req->request_time);
		}
	}

	DEBUG(5,("switch message %s (task_id %u)\n",
		 smb_fn_name(type), (unsigned)req->smb_conn->connection->server_id.id));

	/* this must be called before we do any reply */
	if (flags & SIGNING_NO_REPLY) {
		smbsrv_signing_no_reply(req);
	}

	/* see if the vuid is valid */
	if ((flags & NEED_SESS) && !req->session) {
		status = NT_STATUS_DOS(ERRSRV, ERRbaduid);
		/* amazingly, the error code depends on the command */
		switch (type) {
		case SMBntcreateX:
		case SMBntcancel:
		case SMBulogoffX:
			break;
		default:
			if (req->smb_conn->config.nt_status_support &&
			    req->smb_conn->negotiate.client_caps & CAP_STATUS32) {
				status = NT_STATUS_INVALID_HANDLE;
			}
			break;
		}
		/* 
		 * TODO:
		 * don't know how to handle smb signing for this case 
		 * so just skip the reply
		 */
		if ((flags & SIGNING_NO_REPLY) &&
		    (req->smb_conn->signing.signing_state != SMB_SIGNING_ENGINE_OFF)) {
			DEBUG(1,("SKIP ERROR REPLY: %s %s because of unknown smb signing case\n",
				smb_fn_name(type), nt_errstr(status)));
			talloc_free(req);
			return;
		}
		smbsrv_send_error(req, status);
		return;
	}

	/* does this protocol need a valid tree connection? */
	if ((flags & NEED_TCON) && !req->tcon) {
		status = NT_STATUS_DOS(ERRSRV, ERRinvnid);
		/* amazingly, the error code depends on the command */
		switch (type) {
		case SMBntcreateX:
		case SMBntcancel:
		case SMBtdis:
			break;
		default:
			if (req->smb_conn->config.nt_status_support &&
			    req->smb_conn->negotiate.client_caps & CAP_STATUS32) {
				status = NT_STATUS_INVALID_HANDLE;
			}
			break;
		}
		/* 
		 * TODO:
		 * don't know how to handle smb signing for this case 
		 * so just skip the reply
		 */
		if ((flags & SIGNING_NO_REPLY) &&
		    (req->smb_conn->signing.signing_state != SMB_SIGNING_ENGINE_OFF)) {
			DEBUG(1,("SKIP ERROR REPLY: %s %s because of unknown smb signing case\n",
				smb_fn_name(type), nt_errstr(status)));
			talloc_free(req);
			return;
		}
		smbsrv_send_error(req, status);
		return;
	}

	smb_messages[type].fn(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 smbsrv_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) {
		smbsrv_send_error(req, NT_STATUS_DOS(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);
		smbsrv_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;

	/* fix the bufinfo */
	smbsrv_setup_bufinfo(req);

	req->chain_count++;

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

	/* cleanup somestuff for the next request */
	talloc_free(req->ntvfs);
	req->ntvfs = NULL;
	talloc_free(req->io_ptr);
	req->io_ptr = NULL;

	switch_message(chain_cmd, req);
	return;

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

/*
 * init the SMB protocol related stuff
 */
NTSTATUS smbsrv_init_smb_connection(struct smbsrv_connection *smb_conn, struct loadparm_context *lp_ctx)
{
	NTSTATUS status;

	/* 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(lp_ctx);

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

	smb_conn->config.security = lp_security(lp_ctx);
	smb_conn->config.nt_status_support = lp_nt_status_support(lp_ctx);

	status = smbsrv_init_sessions(smb_conn, UINT16_MAX);
	NT_STATUS_NOT_OK_RETURN(status);

	status = smbsrv_smb_init_tcons(smb_conn);
	NT_STATUS_NOT_OK_RETURN(status);

	smbsrv_init_signing(smb_conn);

	return NT_STATUS_OK;
}