;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;                                                              ;;
;; Copyright (C) KolibriOS team 2004-2007. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License    ;;
;;                                                              ;;
;;                                                              ;;
;; Copyright (C) KolibriOS team 2004-2007. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License    ;;
;;                                                              ;;
;;                                                              ;;
;;  UDP.INC                                                     ;;
;;                                                              ;;
;;  UDP Processes for Menuet OS  TCP/IP stack                   ;;
;;                                                              ;;
;;  Version 0.3  29 August 2002                                 ;;
;;                                                              ;;
;;  Copyright 2002 Mike Hibbett, mikeh@oceanfree.net            ;;
;;                                                              ;;
;;  See file COPYING for details                                ;;
;;                                                              ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

$Revision$


;*******************************************************************
;   Interface
;
;       udp_rx      Handles received IP packets with the UDP protocol
;
;*******************************************************************


;
;   UDP Payload ( Data field in IP datagram )
;
;    0                   1                   2                   3
;    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
;
;   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;   |       Source Port             |      Destination Port         |
;   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;   | Length ( UDP Header + Data )  |           Checksum            |
;   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;   |       UDP Data                                                |
;   +-+-+-..........                                               -+
;

struc UDP_PACKET
{  .SourcePort	     dw  ?  ;+00
   .DestinationPort  dw  ?  ;+02
   .Length	     dw  ?  ;+04 - Length of (UDP Header + Data)
   .Checksum	     dw  ?  ;+06
   .Data	     db  ?  ;+08
}

virtual at 0
  UDP_PACKET UDP_PACKET
end virtual


;***************************************************************************
;   Function
;      udp_rx  [by Johnny_B]
;
;   Description
;       UDP protocol handler
;       This is a kernel function, called by ip_rx
;       IP buffer address given in edx
;          IP buffer number in eax
;          Free up (or re-use) IP buffer when finished
;
;***************************************************************************

proc udp_rx stdcall
	push	eax

	; First validate the header & checksum. Discard buffer if error

	; Look for a socket where
	; IP Packet UDP Destination Port = local Port
	; IP Packet SA = Remote IP

	mov	ax, [edx + 20 + UDP_PACKET.DestinationPort]   ; get the local port from
				       ; the IP packet's UDP header

	mov	ebx, net_sockets_mutex
	call	wait_mutex
	mov	ebx, net_sockets

  .next_socket:
	mov	ebx, [ebx + SOCKET.NextPtr]
	or	ebx, ebx
	jz	.exit					; No match, so exit
	cmp	[ebx + SOCKET.LocalPort], ax		; ax will hold the 'wrong' value,
							; but the comparision is correct
	jne	.next_socket				; Return back if no match

	; For dhcp, we must allow any remote server to respond.
	; I will accept the first incoming response to be the one
	; I bind to, if the socket is opened with a destination IP address of
	; 255.255.255.255
	cmp	[ebx + SOCKET.RemoteIP], 0xffffffff
	je	@f

	mov	eax, [edx + IP_PACKET.SourceAddress]	; get the Source address from the IP packet
	cmp	[ebx + SOCKET.RemoteIP], ebx
	jne	.exit		   ; Quit if the source IP is not valid

    @@: ; OK - we have a valid UDP packet for this socket.
	; First, update the sockets remote port number with the incoming msg
	; - it will have changed
	; from the original ( 69 normally ) to allow further connects
	mov	ax, [edx + 20 + UDP_PACKET.SourcePort]		; get the UDP source port
								; ( was 69, now new )
	mov	[ebx + SOCKET.RemotePort], ax

	; Now, copy data to socket. We have socket address as [eax + sockets].
	; We have IP packet in edx

	; get # of bytes in ecx
	movzx	ecx, [edx + IP_PACKET.TotalLength]	; total length of IP packet. Subtract
	xchg	cl, ch					; 20 + 8 gives data length
	sub	ecx, 28

	mov	eax, [ebx + SOCKET.rxDataCount] 	; get # of bytes already in buffer
	add	[ebx + SOCKET.rxDataCount], ecx 	; increment the count of bytes in buffer

	; ecx has count, edx points to data

	add	edx, 28        ; edx now points to the data
	lea	edi, [ebx + eax + SOCKETHEADERSIZE]
	mov	esi, edx

	cld
	rep	movsb	       ; copy the data across

	; flag an event to the application
	mov	eax, [ebx + SOCKET.PID] 		; get socket owner PID
	mov	ecx, 1
	mov	esi, TASK_DATA + TASKDATA.pid

  .next_pid:
	cmp	[esi], eax
	je	.found_pid
	inc	ecx
	add	esi, 0x20
	cmp	ecx, [TASK_COUNT]
	jbe	.next_pid

	jmp	.exit

  .found_pid:
	shl	ecx, 8
	or	[ecx + SLOT_BASE + APPDATA.event_mask], EVENT_NETWORK ; stack event

	mov	[check_idle_semaphore], 200

  .exit:
	pop	eax
	call	freeBuff    ; Discard the packet
	ret
endp