;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ;;
;; IP.INC ;;
;; ;;
;; IP 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 ;;
;; ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; IP underlying protocols numbers
PROTOCOL_ICMP equ 1
PROTOCOL_TCP equ 6
PROTOCOL_UDP equ 17
struc IP_PACKET
{ .VersionAndIHL db ? ;+00 - Version[0-3 bits] and IHL(header length)[4-7 bits]
.TypeOfService db ? ;+01
.TotalLength dw ? ;+02
.Identification dw ? ;+04
.FlagsAndFragmentOffset dw ? ;+06 - Flags[0-2] and FragmentOffset[3-15]
.TimeToLive db ? ;+08
.Protocol db ? ;+09
.HeaderChecksum dw ? ;+10
.SourceAddress dd ? ;+12
.DestinationAddress dd ? ;+16
.DataOrOptional dd ? ;+20
}
virtual at 0
IP_PACKET IP_PACKET
end virtual
;*******************************************************************
; Interface
;
; ip_rx processes all packets received by the network layer
; It calls the appropriate protocol handler
;
;
;
;*******************************************************************
;
; IP Packet after reception - Normal IP packet format
;
; 0 1 2 3
; 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
;
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;0 |Version| IHL |Type of Service| Total Length |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;4 | Identification |Flags| Fragment Offset |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;8 | Time to Live | Protocol | Header Checksum |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;12 | Source Address |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;16 | Destination Address |
; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;20 | Data |
; +-+-+-.......... -+
;
;
; [smb] attention! according to RFC 791 IP packet may have 'options' sections,
; so we can't simply think, that data have offset 20. We must calculate offset from
; IHL field
;
macro GET_IHL reg, header_addr
{
movzx reg, byte [header_addr]
; we need 4-7 bits, so....
and reg, 0x0000000F
; IHL keeps number of octets, so we need to << 2 'reg'
shl reg, 2
}
;***************************************************************************
; Function
; ip_rx
;
; Description
; This is a kernel function, called by stack_handler
; Processes all IP-packets received by the network layer
; It calls the appropriate protocol handler
;
;***************************************************************************
proc ip_rx stdcall
local buffer_number dd ?
; Look for a buffer to tx
mov eax, IPIN_QUEUE
call dequeue
cmp ax, NO_BUFFER
je .exit ; Exit if no buffer available
mov [buffer_number], eax ;save buffer number
; convert buffer pointer eax to the absolute address
imul eax, IPBUFFSIZE
add eax, IPbuffs
mov ebx, eax ; ebx=pointer to IP_PACKET
; Validate the IP checksum
mov dx, word[ebx + IP_PACKET.HeaderChecksum]
xchg dh,dl ; Get the checksum in intel format
mov [ebx + IP_PACKET.HeaderChecksum], word 0 ; clear checksum field - need to when
; recalculating checksum
; this needs two data pointers and two size #.
; 2nd pointer can be of length 0
GET_IHL ecx, ebx + IP_PACKET.VersionAndIHL ;get packet length in ecx
stdcall checksum_jb, ebx, ecx ;buf_ptr, buf_size
cmp dx, ax
mov edx, ebx ; EDX (IP-BUFFER POINTER) WILL BE USED FOR *_rx HANDLERS BELOW!!!
jnz .dump ;if CHECKSUM isn't valid then dump packet
; Validate the IP address, if it isn't broadcast
mov eax, [stack_ip]
cmp dword[ebx + IP_PACKET.DestinationAddress], eax
je @f
; If the IP address is 255.255.255.255, accept it
; - it is a broadcast packet, which we need for dhcp
cmp dword[ebx + IP_PACKET.DestinationAddress], 0xffffffff
jne .dump
@@:
mov al, [ebx + IP_PACKET.VersionAndIHL]
and al, 0x0f ;get IHL(header length)
cmp al, 0x05 ;if IHL!= 5*4(20 bytes)
jnz .dump ;then dump it
cmp byte[ebx + IP_PACKET.TimeToLive], byte 0
je .dump ;if TTL==0 then dump it
mov ax, word[ebx + IP_PACKET.FlagsAndFragmentOffset]
and ax, 0xFFBF ;get flags
cmp ax, 0 ;if some flags was set then we dump this packet
jnz .dump ;the flags should be used for fragmented packets
; Check the protocol, and call the appropriate handler
; Each handler will re-use or free the queue buffer as appropriate
mov al, [ebx + IP_PACKET.Protocol]
cmp al , PROTOCOL_TCP
jne .not_tcp
DEBUGF 1,"K : ip_rx - TCP packet\n"
mov eax, dword[buffer_number]
call tcp_rx
jmp .exit
.not_tcp:
cmp al, PROTOCOL_UDP
jne .not_udp
DEBUGF 1,"K : ip_rx - UDP packet\n"
mov eax, dword[buffer_number]
call udp_rx
jmp .exit
.not_udp:
cmp al , PROTOCOL_ICMP
jne .dump ;protocol ain't supported
DEBUGF 1,"K : ip_rx - ICMP packet\n"
;GET_IHL ecx, ebx + IP_PACKET.VersionAndIHL ;get packet length in ecx
mov eax, dword[buffer_number]
stdcall icmp_rx,eax,ebx,ecx ;buffer_number,IPPacketBase,IPHeaderLength
jmp .exit
.dump:
; No protocol handler available, so
; silently dump the packet, freeing up the queue buffer
inc dword [dumped_rx_count]
mov eax, dword[buffer_number]
call freeBuff
.exit:
ret
endp