;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;                                                                 ;;
;; Copyright (C) KolibriOS team 2004-2010. All rights reserved.    ;;
;; Distributed under terms of the GNU General Public License       ;;
;;                                                                 ;;
;;  UDP.INC                                                        ;;
;;                                                                 ;;
;;  Part of the tcp/ip network stack for KolibriOS                 ;;
;;                                                                 ;;
;;    Written by hidnplayr@kolibrios.org                           ;;
;;                                                                 ;;
;;          GNU GENERAL PUBLIC LICENSE                             ;;
;;             Version 2, June 1991                                ;;
;;                                                                 ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

$Revision$


struct	UDP_Packet

	SourcePort	       dw  ?
	DestinationPort        dw  ?
	Length		       dw  ?  ; Length of (UDP Header + Data)
	Checksum	       dw  ?

ends


align 4
uglobal
	UDP_PACKETS_TX		rd  MAX_IP
	UDP_PACKETS_RX		rd  MAX_IP
endg


;-----------------------------------------------------------------
;
; UDP_init
;
;  This function resets all UDP variables
;
;-----------------------------------------------------------------
macro	UDP_init {

	xor	eax, eax
	mov	edi, UDP_PACKETS_TX
	mov	ecx, 2*MAX_IP
	rep	stosd
}


macro	UDP_checksum	IP1, IP2  { ; esi = ptr to udp packet, ecx = packet size, destroys: ecx, edx

; Pseudoheader
	mov	edx, IP_PROTO_UDP

	add	dl, [IP1+1]
	adc	dh, [IP1+0]
	adc	dl, [IP1+3]
	adc	dh, [IP1+2]

	adc	dl, [IP2+1]
	adc	dh, [IP2+0]
	adc	dl, [IP2+3]
	adc	dh, [IP2+2]

	adc	dl, cl ; byte[esi+UDP_Packet.Length+1]
	adc	dh, ch ; byte[esi+UDP_Packet.Length+0]

; Done with pseudoheader, now do real header
	adc	dl, byte[esi+UDP_Packet.SourcePort+1]
	adc	dh, byte[esi+UDP_Packet.SourcePort+0]

	adc	dl, byte[esi+UDP_Packet.DestinationPort+1]
	adc	dh, byte[esi+UDP_Packet.DestinationPort+0]

	adc	dl, byte[esi+UDP_Packet.Length+1]
	adc	dh, byte[esi+UDP_Packet.Length+0]

	adc	edx, 0

; Done with header, now do data
	push	esi
	movzx	ecx, [esi+UDP_Packet.Length]
	rol	cx , 8
	sub	cx , sizeof.UDP_Packet
	add	esi, sizeof.UDP_Packet

	call	checksum_1
	call	checksum_2
	pop	esi

	add	[esi+UDP_Packet.Checksum], dx	; this final instruction will set or clear ZF :)

}


;-----------------------------------------------------------------
;
; UDP_input:
;
;  Called by IPv4_input,
;  this procedure will inject the udp data diagrams in the application sockets.
;
;  IN:   [esp]  = Pointer to buffer
;       [esp+4] = size of buffer
;       ebx = ptr to device struct
;       ecx = UDP Packet size
;       edx = ptr to UDP header
;
;       esi = ipv4 source address
;       edi = ipv4 dest   address
;
;  OUT: /
;
;-----------------------------------------------------------------
align 4
UDP_input:

	DEBUGF	1,"UDP_input, size:%u\n", ecx

; First validate, checksum:
	neg	[edx+UDP_Packet.Checksum]	; substract chechksum from 0
	jz	.no_checksum			; if checksum is zero, it is considered valid and we continue processing
						; otherwise, we will re-calculate the checksum and add it to this value, thus creating 0 when it is correct

	push	edx
	push	edi
	push	esi
	mov	esi, edx
	UDP_checksum (esp), (esp+4)
	pop	edi
	pop	esi	; we dont need it, but it is smaller then add esp, 4
	pop	edx
	jnz	.checksum_mismatch

  .no_checksum:
	DEBUGF	1,"UDP Checksum is correct\n"

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

	mov	eax, net_sockets
  .try_more:
	mov	si , [edx + UDP_Packet.DestinationPort]   ; get the local port from the IP Packet's UDP header
	rol	si , 8
  .next_socket:
	mov	eax, [eax + SOCKET.NextPtr]
	or	eax, eax
	jz	.dump
	cmp	[eax + SOCKET.Domain], AF_INET4
	jne	.next_socket
	cmp	[eax + SOCKET.Protocol], IP_PROTO_UDP
	jne	.next_socket
	cmp	[eax + UDP_SOCKET.LocalPort], si
	jne	.next_socket

	DEBUGF	1,"using socket: %x\n", eax

	;;; TODO: when packet is processed, check more sockets!

	cmp	[eax + IP_SOCKET.RemoteIP], 0xffffffff
	je	@f
	cmp	[eax + IP_SOCKET.RemoteIP], edi 	; edi is the packets source address
	jne	.try_more
       @@:

	cmp	[eax + UDP_SOCKET.firstpacket], 0
	jz	.updateport

	mov	si, [edx + UDP_Packet.SourcePort]
	rol	si, 8
	cmp	[eax + UDP_SOCKET.RemotePort], si
	jne	.dump

	push	ebx
	lea	ebx, [eax + SOCKET.lock]
	call	wait_mutex
	pop	ebx

  .updatesock:
	inc	[UDP_PACKETS_RX]
	DEBUGF	1,"Found valid UDP packet for socket %x\n", eax
	lea	esi, [edx + sizeof.UDP_Packet]
	movzx	ecx, [edx + UDP_Packet.Length]
	rol	cx , 8
	sub	cx , sizeof.UDP_Packet

	jmp	SOCKET_input

  .updateport:
	push	ebx
	lea	ebx, [eax + SOCKET.lock]
	call	wait_mutex
	pop	ebx

	mov	si, [edx + UDP_Packet.SourcePort]
	rol	si, 8
	DEBUGF	1,"Changing remote port to: %u\n", si
	mov	[eax + UDP_SOCKET.RemotePort], si
	inc	[eax + UDP_SOCKET.firstpacket]

	jmp	.updatesock


  .checksum_mismatch:

	DEBUGF	2,"UDP_Handler - checksum mismatch\n"

  .dump:
	call	kernel_free
	add	esp, 4 ; pop (balance stack)
	DEBUGF	2,"UDP_Handler - dumping\n"

	ret




;-----------------------------------------------------------------
;
; UDP_output
;
; IN: eax = socket pointer
;     ecx = number of bytes to send
;     esi = pointer to data
;
;-----------------------------------------------------------------

align 4
UDP_output:

	DEBUGF	1,"UDP_output: socket:%x, bytes: %u, data ptr: %x\n", eax, ecx, esi

	mov	dx, [eax + UDP_SOCKET.RemotePort]
	DEBUGF	1,"remote port: %u\n", dx
	rol	dx, 8
	rol	edx, 16
	mov	dx, [eax + UDP_SOCKET.LocalPort]
	DEBUGF	1,"local port: %u\n", dx
	rol	dx, 8

	mov	ebx, [eax + IP_SOCKET.LocalIP]
	mov	eax, [eax + IP_SOCKET.RemoteIP]

	mov	di, IP_PROTO_UDP shl 8 + 128
	sub	esp, 8						; Data ptr and data size will be placed here
	add	ecx, sizeof.UDP_Packet

;;; TODO: fragment id
	push	edx esi
	call	IPv4_output
	jz	.fail

	mov	[esp + 8], eax					; pointer to buffer start
	mov	[esp + 8 + 4], edx				; buffer size

	mov	[edi + UDP_Packet.Length], cx
	rol	[edi + UDP_Packet.Length], 8

	pop	esi
	push	edi ecx
	sub	ecx, sizeof.UDP_Packet
	add	edi, sizeof.UDP_Packet
	shr	ecx, 2
	rep	movsd
	mov	ecx, [esp]
	and	ecx, 3
	rep	movsb
	pop	ecx edi

	pop	dword [edi + UDP_Packet.SourcePort]

; Checksum
	mov	esi, edi
	mov	[edi + UDP_Packet.Checksum], 0
	UDP_checksum (edi-4), (edi-8)				; TODO: fix this, IPv4 packet could have options..

	inc	[UDP_PACKETS_TX]

	DEBUGF	1,"Sending UDP Packet to device %x\n", ebx

	call	[ebx + NET_DEVICE.transmit]
	ret

  .fail:
	DEBUGF	1,"UDP_output: failed\n"
	add	esp, 4+4+8
	xor	eax, eax
	ret



;---------------------------------------------------------------------------
;
; UDP_API
;
; This function is called by system function 75
;
; IN:  subfunction number in bl
;      device number in bh
;      ecx, edx, .. depends on subfunction
;
; OUT:
;
;---------------------------------------------------------------------------

align 4
UDP_API:

	movzx	eax, bh
	shl	eax, 2

	test	bl, bl
	jz	.packets_tx	; 0
	dec	bl
	jz	.packets_rx	; 1

.error:
	mov	eax, -1
	ret

.packets_tx:
	add	eax, UDP_PACKETS_TX
	mov	eax, [eax]
	ret

.packets_rx:
	add	eax, UDP_PACKETS_RX
	mov	eax, [eax]
	ret