Subversion Repositories Kolibri OS

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;                                                                 ;;

;; Copyright (C) KolibriOS team 2004-2010. All rights reserved.    ;;

;; Distributed under terms of the GNU General Public License       ;;

;;                                                                 ;;

;;  IPv4.INC                                                       ;;

;;                                                                 ;;

;;  Part of the tcp/ip network stack for KolibriOS                 ;;

;;                                                                 ;;

;;  Based on the work of [Johnny_B] and [smb]                      ;;

;;                                                                 ;;

;;    Written by hidnplayr@kolibrios.org                           ;;

;;                                                                 ;;

;;          GNU GENERAL PUBLIC LICENSE                             ;;

;;             Version 2, June 1991                                ;;

;;                                                                 ;;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

$Revision: 1530 $

MAX_FRAGMENTS	equ 64

MAX_IP		equ MAX_NET_DEVICES

IP_MAX_INTERFACES   equ MAX_IP

struct	IPv4_Packet

	.VersionAndIHL		db  ?  ; Version[0-3 bits] and IHL(header length)[4-7 bits]

	.TypeOfService		db  ?  ; precedence [7-5] minimize delay [4], maximize throughput [3], maximize riliability [2] minimize momentary cost [1] and zero [0]

	.TotalLength		dw  ?

	.Identification 	dw  ?

	.FlagsAndFragmentOffset dw  ?  ; Flags[0-2] and FragmentOffset[3-15]

	.TimeToLive		db  ?  ;

	.Protocol		db  ?

	.HeaderChecksum 	dw  ?

	.SourceAddress		dd  ?

	.DestinationAddress	dd  ?

	.DataOrOptional:

ends

struct	FRAGMENT_slot

	.ttl			dw  ?  ; Time to live for this entry, 0 for empty slot's

	.id			dw  ?  ; Identification field from IP header

	.SrcIP			dd  ?  ; .. from IP header

	.DstIP			dd  ?  ; .. from IP header

	.ptr			dd  ?  ; Pointer to first packet

	.size:

ends

struct	FRAGMENT_entry		       ; This structure will replace the ethernet header in fragmented ip packets

	.PrevPtr		dd  ?  ; Pointer to previous fragment entry  (-1 for first packet)

	.NextPtr		dd  ?  ; Pointer to next fragment entry (-1 for last packet)

	.Owner			dd  ?  ; Pointer to structure of driver

				rb  2  ; to match ethernet header size          ; TODO: fix this hack

	.Data:			       ; Ip header begins here (we will need the IP header to re-construct the complete packet)

ends

align 4

uglobal

	IP_LIST 	rd  MAX_IP

	SUBNET_LIST	rd  MAX_IP

	DNS_LIST	rd  MAX_IP

	GATEWAY_LIST	rd  MAX_IP

	IP_PACKETS_TX	rd  MAX_IP

	IP_PACKETS_RX	rd  MAX_IP

	FRAGMENT_LIST	rb  MAX_FRAGMENTS*FRAGMENT_slot.size

endg

;-----------------------------------------------------------------

;

; IPv4_init

;

;  This function resets all IP variables

;

;-----------------------------------------------------------------

macro	IPv4_init {

	xor	eax, eax

	mov	edi, IP_LIST

	mov	ecx, 4*MAX_IP

	rep	stosd

	mov	edi, FRAGMENT_LIST

	mov	ecx, FRAGMENT_slot.size*MAX_FRAGMENTS/4 + 2*MAX_IP

	rep	stosd

}

;-----------------------------------------------------------------

;

; Decrease TimeToLive of all fragment slots

;

;-----------------------------------------------------------------

macro IPv4_decrease_fragment_ttls {

local	.loop

	mov	esi, FRAGMENT_LIST

	mov	ecx, MAX_FRAGMENTS

  .loop:

	cmp	[esi + FRAGMENT_slot.ttl], 0

	je	.try_next

	dec	[esi + FRAGMENT_slot.ttl]

	jnz	.try_next

	DEBUGF 1,"Fragment slot timed-out!\n"

;;; TODO: clear all entry's of timed-out slot

  .try_next:

	add	esi, 4

	loop	.loop

}

macro IPv4_checksum ptr {

; This is the fast procedure to create or check a IP header without options

; To create a new checksum, the checksum field must be set to 0 before computation

; To check an existing checksum, leave the checksum as is, and it will be 0 after this procedure, if it was correct

	push	ebx

	xor	ebx, ebx

	add	bl, [ptr+1]

	adc	bh, [ptr+0]

	adc	bl, [ptr+3]

	adc	bh, [ptr+2]

	adc	bl, [ptr+5]

	adc	bh, [ptr+4]

	adc	bl, [ptr+7]

	adc	bh, [ptr+6]

	adc	bl, [ptr+9]

	adc	bh, [ptr+8]

; we skip 11th and 12th byte, they are the checksum bytes and should be 0 for re-calculation

	adc	bl, [ptr+13]

	adc	bh, [ptr+12]

	adc	bl, [ptr+15]

	adc	bh, [ptr+14]

	adc	bl, [ptr+17]

	adc	bh, [ptr+16]

	adc	bl, [ptr+19]

	adc	bh, [ptr+18]

	adc	ebx, 0

	push	ecx

	mov	ecx, ebx

	shr	ecx, 16

	and	ebx, 0xffff

	add	ebx, ecx

	mov	ecx, ebx

	shr	ecx, 16

	add	ebx, ecx

	not	bx

	jnz	.not_zero

	dec	bx

  .not_zero:

	xchg	bl, bh

	pop	ecx

	neg	word [ptr+10]		; zero will stay zero so we just get the checksum

	add	word [ptr+10], bx	;  , else we will get (new checksum - old checksum) in the end, wich should be 0 :)

	pop	ebx

}

;-----------------------------------------------------------------

;

; IPv4_input:

;

;  Will check if IP Packet isnt damaged

;  and call appropriate handler. (TCP/UDP/ICMP/..)

;

;  It will also re-construct fragmented packets

;

;  IN:  Pointer to buffer in [esp]

;       size of buffer in [esp+4]

;       pointer to device struct in ebx

;       pointer to IP Packet data in edx

;  OUT: /

;

;-----------------------------------------------------------------

align 4

IPv4_input:	 ; TODO: implement handler for IP options

		 ; TODO2: add code for raw sockets

	DEBUGF	1,"IPv4_Handler, packet from: %u.%u.%u.%u ",\

	[edx + IPv4_Packet.SourceAddress]:1,[edx + IPv4_Packet.SourceAddress + 1]:1,[edx + IPv4_Packet.SourceAddress + 2]:1,[edx + IPv4_Packet.SourceAddress + 3]:1

	DEBUGF	1,"to: %u.%u.%u.%u\n",\

	[edx + IPv4_Packet.DestinationAddress]:1,[edx + IPv4_Packet.DestinationAddress + 1]:1,[edx + IPv4_Packet.DestinationAddress + 2]:1,[edx + IPv4_Packet.DestinationAddress + 3]:1

;-------------------------------------------

; Check if the packet still has time to live

	cmp	byte [edx + IPv4_Packet.TimeToLive], 0

	je	.dump

;--------------------------------------

; First, check if IP packet has options

	movzx	eax, [edx + IPv4_Packet.VersionAndIHL]

	and	al , 0x0f					; get IHL(header length)

	cmp	al , 0x05					; IHL!= 5*4(20 bytes)

	jnz	.has_options

;-------------------------------

; Now, re-calculate the checksum

	IPv4_checksum edx

	jnz	.dump						; if checksum isn't valid then dump packet

	DEBUGF	1,"IPv4 Checksum is correct\n"

;-----------------------------------

; Check if destination IP is correct

	call	NET_ptr_to_num

	shl	edi, 2

	; check if it matches local ip

	mov	eax, dword[IP_LIST+edi]

	cmp	[edx + IPv4_Packet.DestinationAddress], eax

	je	.ip_ok

	; check for broadcast

	mov	eax, dword[SUBNET_LIST+edi]

	not	eax

	or	eax, dword[IP_LIST+edi]

	cmp	[edx + IPv4_Packet.DestinationAddress], eax

	je	.ip_ok

	; or a special broadcast

	cmp	[edx + IPv4_Packet.DestinationAddress], -1

	je	.ip_ok

	; maybe it's a multicast then

	mov	eax, [edx + IPv4_Packet.DestinationAddress]

	and	eax, 0xff000000

;        cmp     eax, 224 shl 24

;        je      .ip_ok

	; or a loopback address

	cmp	eax, 127 shl 24

	je	.ip_ok

	; or it's not meant for us..

	DEBUGF	2,"Destination address does not match!\n"

	jmp	.dump

;------------------------

; Now we can update stats

  .ip_ok:

	inc	[IP_PACKETS_RX+edi]

;----------------------------------

; Check if the packet is fragmented

	test	[edx + IPv4_Packet.FlagsAndFragmentOffset], 1 shl 5	; Is 'more fragments' flag set ?

	jnz	.has_fragments						; If so, we definately have a fragmented packet

	test	[edx + IPv4_Packet.FlagsAndFragmentOffset], 0xff1f	; If flag is not set, but there is a fragment offset, the packet is last in series of fragmented packets

	jnz	.is_last_fragment

;-------------------------------------------------------------------

; No, it's just a regular IP packet, pass it to the higher protocols

  .handle_it:							; We reach here if packet hasnt been fragmented, or when it already has been re-constructed

	movzx	eax, byte [edx + IPv4_Packet.VersionAndIHL]	; Calculate Header length by using IHL field

	and	eax, 0x0000000f 				;

	shl	eax, 2						;

	movzx	ecx, word [edx + IPv4_Packet.TotalLength]	; Calculate length of encapsulated Packet

	xchg	cl , ch 					;

	sub	ecx, eax					;

	add	eax, edx

	push	eax

	mov	esi, [edx + IPv4_Packet.SourceAddress]		; These values might be of interest to the higher protocols

	mov	edi, [edx + IPv4_Packet.DestinationAddress]	;

	mov	al , [edx + IPv4_Packet.Protocol]

	pop	edx						; Offset to data (tcp/udp/icmp/.. Packet)

	cmp	al , IP_PROTO_TCP

	je	TCP_input

	cmp	al , IP_PROTO_UDP

	je	UDP_input

	cmp	al , IP_PROTO_ICMP

	je	ICMP_input

	DEBUGF	2,"unknown Internet protocol: %u\n", al

  .dump:

	DEBUGF	2,"IP_Handler - dumping\n"

;        inc     [dumped_rx_count]

	call	kernel_free

	add	esp, 4						; pop (balance stack)

	ret

;---------------------------

; Fragmented packet handler

  .has_fragments:

	movzx	eax, [edx + IPv4_Packet.FlagsAndFragmentOffset]

	xchg	al , ah

	shl	ax , 3

	DEBUGF	1,"Fragmented packet, offset:%u, id:%x\n", ax, [edx + IPv4_Packet.Identification]:4

	test	ax , ax 					; Is this the first packet of the fragment?

	jz	.is_first_fragment

;-------------------------------------------------------

; We have a fragmented IP packet, but it's not the first

	DEBUGF	1,"Middle fragmented packet received!\n"

	call	IPv4_find_fragment_slot

	cmp	esi, -1

	je	.dump

	mov	word [esi + FRAGMENT_slot.ttl], 15		; Reset the ttl

	mov	esi, [esi + FRAGMENT_slot.ptr]

	or	edi, -1

  .find_last_entry:						; The following routine will try to find the last entry

	cmp	edi, [esi + FRAGMENT_entry.PrevPtr]

	jne	.destroy_slot					; Damn, something screwed up, remove the whole slot (and free buffers too if possible!)

	mov	edi, esi

	mov	esi, [esi + FRAGMENT_entry.NextPtr]

	cmp	esi, -1

	jne	.find_last_entry

								; We found the last entry (pointer is now in edi)

								; We are going to overwrite the ethernet header in received packet with a FRAGMENT_entry structure

	pop	eax						; pointer to packet

	mov	[edi + FRAGMENT_entry.NextPtr], eax		; update pointer of previous entry to the new entry

	mov	[eax + FRAGMENT_entry.NextPtr], -1

	mov	[eax + FRAGMENT_entry.PrevPtr], edi

	mov	[eax + FRAGMENT_entry.Owner], ebx

	add	esp, 4

	ret

;------------------------------------

; We have received the first fragment

  .is_first_fragment:

	DEBUGF	1,"First fragmented packet received!\n"

								; try to locate a free slot..

	mov	ecx, MAX_FRAGMENTS

	mov	esi, FRAGMENT_LIST

  .find_free_slot:

	cmp	word [esi + FRAGMENT_slot.ttl], 0

	je	.found_free_slot

	add	esi, FRAGMENT_slot.size

	loop	.find_free_slot

	jmp	.dump						; If no free slot was found, dump the packet

  .found_free_slot:						; We found a free slot, let's fill in the FRAGMENT_slot structure

	mov	word [esi + FRAGMENT_slot.ttl], 15		; RFC recommends 15 secs as ttl

	mov	ax , word [edx + IPv4_Packet.Identification]

	mov	word [esi + FRAGMENT_slot.id], ax

	mov	eax, dword [edx + IPv4_Packet.SourceAddress]

	mov	dword [esi + FRAGMENT_slot.SrcIP], eax

	mov	eax, dword [edx + IPv4_Packet.DestinationAddress]

	mov	dword [esi + FRAGMENT_slot.DstIP], eax

	pop	eax

	mov	dword [esi + FRAGMENT_slot.ptr], eax

								; Now, replace ethernet header in original buffer with a FRAGMENT_entry structure

	mov	[eax + FRAGMENT_entry.NextPtr], -1

	mov	[eax + FRAGMENT_entry.PrevPtr], -1

	mov	[eax + FRAGMENT_entry.Owner], ebx

	add	esp, 4						; balance stack and exit

	ret

;-----------------------------------

; We have received the last fragment

  .is_last_fragment:

	DEBUGF	1,"Last fragmented packet received!\n"

	call	IPv4_find_fragment_slot

	cmp	esi, -1

	je	.dump

	mov	esi, [esi + FRAGMENT_slot.ptr]			; We found the first entry, let's calculate total size of the packet in eax, so we can allocate a buffer

	push	esi

	xor	eax, eax

	or	edi, -1

  .count_bytes:

	cmp	[esi + FRAGMENT_entry.PrevPtr], edi

	jne	.destroy_slot_pop						  ; Damn, something screwed up, remove the whole slot (and free buffers too if possible!)

	mov	cx, word [esi + FRAGMENT_entry.Data + IPv4_Packet.TotalLength]	  ; Add total length

	xchg	cl, ch

	DEBUGF	1,"Packet size: %u\n", cx

	add	ax, cx

	movzx	cx, byte [esi + FRAGMENT_entry.Data + IPv4_Packet.VersionAndIHL]  ; Sub Header length

	and	cx, 0x000F

	shl	cx, 2

	DEBUGF	1,"Header size: %u\n", cx

	sub	ax, cx

	mov	edi, esi

	mov	esi, [esi + FRAGMENT_entry.NextPtr]

	cmp	esi, -1

	jne	.count_bytes

	mov	esi, [esp+4]

	mov	[edi + FRAGMENT_entry.NextPtr], esi			       ; Add this packet to the chain, this simplifies the following code

	mov	[esi + FRAGMENT_entry.NextPtr], -1

	mov	[esi + FRAGMENT_entry.PrevPtr], edi

	mov	[esi + FRAGMENT_entry.Owner], ebx

	mov	cx, [edx + IPv4_Packet.TotalLength]			       ; Note: This time we dont substract Header length

	xchg	cl , ch

	DEBUGF	1,"Packet size: %u\n", cx

	add	ax , cx

	DEBUGF	1,"Total Received data size: %u\n", eax

	push	eax

	mov	ax , [edx + IPv4_Packet.FlagsAndFragmentOffset]

	xchg	al , ah

	shl	ax , 3

	add	cx , ax

	pop	eax

	DEBUGF	1,"Total Fragment size: %u\n", ecx

	cmp	ax, cx

	jne	.destroy_slot_pop

	push	eax

	push	eax

	call	kernel_alloc

	test	eax, eax

	je	.destroy_slot_pop							; If we dont have enough space to allocate the buffer, discard all packets in slot

	mov	edx, [esp+4]								; Get pointer to first fragment entry back in edx

  .rebuild_packet_loop:

	movzx	ecx, word [edx + FRAGMENT_entry.Data + IPv4_Packet.FlagsAndFragmentOffset]	; Calculate the fragment offset

	xchg	cl , ch 									;  intel byte order

	shl	cx , 3										;   multiply by 8 and clear first 3 bits

	DEBUGF	1,"Fragment offset: %u\n", cx

	lea	edi, [eax + ecx]								; Notice that edi will be equal to eax for first fragment

	movzx	ebx, byte [edx + FRAGMENT_entry.Data + IPv4_Packet.VersionAndIHL]		; Find header size (in ebx) of fragment

	and	bx , 0x000F									;

	shl	bx , 2										;

	lea	esi, [edx + FRAGMENT_entry.Data]						; Set esi to the correct begin of fragment

	movzx	ecx, word [edx + FRAGMENT_entry.Data + IPv4_Packet.TotalLength] 		; Calculate total length of fragment

	xchg	cl, ch										;  intel byte order

	cmp	edi, eax									; Is this packet the first fragment ?

	je	.first_fragment

	sub	cx, bx										; If not, dont copy the header

	add	esi, ebx									;

  .first_fragment:

	push	cx										; First copy dword-wise, then byte-wise

	shr	cx, 2										;

	rep	movsd										;

	pop	cx										;

	and	cx, 3										;

	rep	movsb										;

	push	eax

	push	edx										; Push pointer to fragment onto stack

	mov	ebx, [edx + FRAGMENT_entry.Owner]						; we need to remeber the owner, in case this is the last packet

	mov	edx, [edx + FRAGMENT_entry.NextPtr]						; Set edx to the next pointer

	call	kernel_free									; free the previous fragment buffer (this uses the value from stack)

	pop	eax

	cmp	edx, -1 									; Check if it is last fragment in chain

	jne	.rebuild_packet_loop

	pop	ecx										;

	xchg	cl, ch

	mov	edx, eax

	mov	word [edx + IPv4_Packet.TotalLength], cx

	add	esp, 8

	xchg	cl, ch		    ;

	push	ecx		   ;;;;

	push	eax		   ;;;;

;        mov     esi, edx           ;  This prints the IP packet to the debug board (usefull when using serial output debug..)

;                                   ;

;        packet_to_debug

	jmp	.handle_it	    ; edx = buf ptr, ecx = size, [esp] buf ptr, [esp+4], total size, ebx=device ptr

  .destroy_slot_pop:

	add	esp, 4

  .destroy_slot:

	DEBUGF	1,"Destroy fragment slot!\n"

	; TODO!

	jmp	.dump

;-----------------------------------

; The IP packet has some options

  .has_options:

	jmp	.dump

;-----------------------------------------------------------------

;

; find fragment slot

;

; IN: pointer to fragmented packet in edx

; OUT: pointer to slot in edi, -1 on error

;

;-----------------------------------------------------------------

align 4

IPv4_find_fragment_slot:

;;; TODO: the RFC says we should check protocol number too

	push	eax ebx ecx edx

	mov	ax , word [edx + IPv4_Packet.Identification]

	mov	ecx, MAX_FRAGMENTS

	mov	esi, FRAGMENT_LIST

	mov	ebx, dword [edx + IPv4_Packet.SourceAddress]

	mov	edx, dword [edx + IPv4_Packet.DestinationAddress]

  .find_slot:

	cmp	word [esi + FRAGMENT_slot.id], ax

	jne	.try_next

	cmp	dword [esi + FRAGMENT_slot.SrcIP], ebx

	jne	.try_next

	cmp	dword [esi + FRAGMENT_slot.DstIP], edx

	je	.found_slot

  .try_next:

	add	esi, FRAGMENT_slot.size

	loop	.find_slot

;        pop     edx ebx

	or	esi, -1

;        ret

  .found_slot:

	pop	edx ecx ebx eax

	ret

;------------------------------------------------------------------

;

; IPv4_output

;

; IN: eax = dest ip

;     ebx = source ip

;     ecx = data length

;     dx  = fragment id

;     di  = TTL shl 8 + protocol

;

; OUT: eax = pointer to buffer start

;      ebx = pointer to device struct (needed for sending procedure)

;      ecx = unchanged (packet size of embedded data)

;      edx = size of complete buffer

;      edi = pointer to start of data (0 on error)

;

;------------------------------------------------------------------

align 4

IPv4_output:

	DEBUGF 1,"IPv4_create_packet: size=%u\n", ecx

	cmp	ecx, 65500		; Max IPv4 packet size

	jg	.too_large

	push	ecx eax ebx dx di

	call	ARP_IP_to_MAC

	test	eax, 0xffff0000 	; error bits

	jnz	.arp_error

  .continue:

	push	ebx	; push the mac

	push	ax

	call	IPv4_dest_to_dev

	inc	[IP_PACKETS_TX+edi]

	mov	ebx, [NET_DRV_LIST+edi]

	lea	eax, [ebx + ETH_DEVICE.mac]

	mov	edx, esp

	mov	ecx, [esp + 18]

	add	ecx, IPv4_Packet.DataOrOptional

	mov	di , ETHER_IPv4

	call	ETH_output

	jz	.error

	add	esp, 6	; pop the mac

	mov	[edi + IPv4_Packet.VersionAndIHL], 0x45 ; IPv4, normal length (no Optional header)

	mov	[edi + IPv4_Packet.TypeOfService], 0	; nothing special, just plain ip packet

	mov	[edi + IPv4_Packet.TotalLength], cx

	rol	[edi + IPv4_Packet.TotalLength], 8	; internet byte order

	mov	[edi + IPv4_Packet.FlagsAndFragmentOffset], 0x0000

	mov	[edi + IPv4_Packet.HeaderChecksum], 0

	popw	word [edi + IPv4_Packet.TimeToLive]	; ttl shl 8 + protocol

;               [edi + IPv4_Packet.Protocol]

	popw	[edi + IPv4_Packet.Identification]	; fragment id

	popd	[edi + IPv4_Packet.SourceAddress]

	popd	[edi + IPv4_Packet.DestinationAddress]

	pop	ecx

	IPv4_checksum edi

	add	edi, IPv4_Packet.DataOrOptional

	DEBUGF	1,"IPv4 Packet for device %x created successfully\n", ebx

	ret

  .error:

	add	esp, 6

  .arp_error:

	add	esp, 4+4+4+2+2

  .too_large:

	DEBUGF	1,"IPv4_create_packet: Failed\n"

	sub	edi, edi

	ret

;--------------------------------------------------------

;

;

; IN: dword [esp] = pointer to buffer containing ipv4 packet to be fragmented

;     dword [esp+4] = buffer size

;     esi = pointer to ip header in that buffer

;     ecx = max size of fragments

;

; OUT: /

;

;--------------------------------------------------------

align 4

IPv4_fragment:

	DEBUGF 1,"IPv4_fragment\n"

	and	ecx, not 111b	; align 4

	cmp	ecx, IPv4_Packet.DataOrOptional + 8	; must be able to put at least 8 bytes

	jl	.err2

	push	esi ecx

	mov	eax, [esi + IPv4_Packet.DestinationAddress]

	call	ARP_IP_to_MAC

	pop	ecx esi

	cmp	eax, -1

	jz	.err2

	push	ebx

	push	ax

	mov	ebx, [NET_DRV_LIST]

	lea	eax, [ebx + ETH_DEVICE.mac]

	push	eax

	push	esi		; ptr to ip header

	sub	ecx, 20 	; substract header size

	push	ecx		; max data size

	push	dword 0 	; offset

  .new_fragment:

	DEBUGF 1,"Ipv4_fragment - new_fragmentn"

	mov	eax, [esp + 3*4]

	lea	ebx, [esp + 4*4]

	mov	di , ETHER_IPv4

	call	ETH_output

	cmp	edi, -1

	jz	.err

; copy header

	mov	esi, [esp + 2*4]

	mov	ecx, 5	; 5 dwords: TODO: use IHL field of the header!

	rep	movsd

; copy data

	mov	esi, [esp + 2*4]

	add	esi, 20

	add	esi, [esp]	; offset

	mov	ecx, [esp + 1*4]

	DEBUGF 1,"IPv4_fragment - copying data (%u bytes)\n", ecx

	rep	movsb

; now, correct header

	mov	ecx, [esp + 1*4]

	add	ecx, 20

	xchg	cl, ch

	mov	[edi + IPv4_Packet.TotalLength], cx

	mov	ecx, [esp]		; offset

	xchg	cl, ch

;        cmp     dword[esp + 4*4], 0     ; last fragment?;<<<<<<

;        je      .last_fragment

	or	cx, 1 shl 2		; more fragments

;  .last_fragment:

	mov	[edi + IPv4_Packet.FlagsAndFragmentOffset], cx

	mov	[edi + IPv4_Packet.HeaderChecksum], 0

	;<<<<<<<<<<<<<<<<<<<<<<<<<<<<< send the packet

	mov	ecx, [esp + 1*4]

	push	edx eax

	IPv4_checksum edi

	call	[ebx + NET_DEVICE.transmit]

	;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

	mov	ecx,  [esp+4]

	add	[esp], ecx

	mov	ecx, [esp+3*4+6+4]	; ptr to begin of buff

	add	ecx, [esp+3*4+6+4+4]	; buff size

	sub	ecx, [esp+2*4]		; ptr to ip header

	add	ecx, [esp]		; offset

	DEBUGF 1,"Ipv4_fragment - bytes remaining: %u\n", ecx

	cmp	ecx, [esp+1*4]

	jge	.new_fragment

	mov	[esp+4], ecx		; set fragment size to remaining packet size

	jmp	.new_fragment

      .err:

	DEBUGF 1,"Ipv4_fragment - failed\n"

      .done:

	add	esp, 12 + 4 + 6

      .err2:

	DEBUGF 1,"Ipv4_fragment - dumping\n"

	call	kernel_free

	add	esp, 4

	ret

;---------------------------------------------------------------------------

;

; IPv4_dest_to_dev

;

; IN:  eax = Destination IP

; OUT: edi = device id * 4

;

;---------------------------------------------------------------------------

align 4

IPv4_dest_to_dev:

	cmp	eax, 0xffffffff

	je	.invalid

	xor	edi, edi

	mov	ecx, MAX_IP

  .loop:

	mov	ebx, [IP_LIST+edi]

	and	ebx, [SUBNET_LIST+edi]

	jz	.next

	mov	edx, eax

	and	edx, [SUBNET_LIST+edi]

	cmp	ebx, edx

	je	.found_it

  .next:

	add	edi, 4

	loop	.loop

  .invalid:

	xor	edi, edi			; if none found, use device 0 as default device

  .found_it:

	DEBUGF	1,"IPv4_dest_to_dev: %u\n", edi

	ret

;---------------------------------------------------------------------------

;

; IPv4_get_frgmnt_num

;

; IN: /

; OUT: fragment number in ax

;

;---------------------------------------------------------------------------

align 4

IPv4_get_frgmnt_num:

	xor	ax, ax	;;; TODO: replace this with real code

	ret

;---------------------------------------------------------------------------

;

; IPv4_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

IPv4_API:

	movzx	eax, bh

	shl	eax, 2

	test	bl, bl

	jz	.packets_tx	; 0

	dec	bl

	jz	.packets_rx	; 1

	dec	bl

	jz	.read_ip	; 2

	dec	bl

	jz	.write_ip	; 3

	dec	bl

	jz	.read_dns	; 4

	dec	bl

	jz	.write_dns	; 5

	dec	bl

	jz	.read_subnet	; 6

	dec	bl

	jz	.write_subnet	; 7

	dec	bl

	jz	.read_gateway	; 8

	dec	bl

	jz	.write_gateway	; 9

  .error:

	mov	eax, -1

	ret

  .packets_tx:

	add	eax, IP_PACKETS_TX

	mov	eax, [eax]

	ret

  .packets_rx:

	add	eax, IP_PACKETS_RX

	mov	eax, [eax]

	ret

  .read_ip:

	add	eax, IP_LIST

	mov	eax, [eax]

	ret

  .write_ip:

	add	eax, IP_LIST

	mov	[eax], ecx

	xor	eax, eax

	ret

  .read_dns:

	add	eax, DNS_LIST

	mov	eax, [eax]

	ret

  .write_dns:

	add	eax, DNS_LIST

	mov	[eax], ecx

	xor	eax, eax

	ret

  .read_subnet:

	add	eax, SUBNET_LIST

	mov	eax, [eax]

	ret

  .write_subnet:

	add	eax, SUBNET_LIST

	mov	[eax], ecx

	xor	eax, eax

	ret

  .read_gateway:

	add	eax, GATEWAY_LIST

	mov	eax, [eax]

	ret

  .write_gateway:

	add	eax, GATEWAY_LIST

	mov	[eax], ecx

	xor	eax, eax

	ret