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;;                                                                 ;;

;;  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                                   ;;

;;                                                                 ;;

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

$Revision: 2434 $

; 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

}

include "tcp.inc"

include "udp.inc"

include "icmp.inc"

;***************************************************************************

;   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

;        DEBUGF  1, "K : ip_rx - proto: %u\n", [ebx + IP_PACKET.Protocol]:1

    ; 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], 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

;        DEBUGF  1, "K : ip_rx - checksums: %x - %x\n", dx, ax

        jnz     .dump.1;if CHECKSUM isn't valid then dump packet

        mov     edx, ebx; EDX (IP-BUFFER POINTER) WILL BE USED FOR *_rx HANDLERS BELOW!!!

;        DEBUGF  1, "K : ip_rx - dest: %x - %x\n", [ebx + IP_PACKET.DestinationAddress], [stack_ip]

    ; 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

        mov     eax, [ebx + IP_PACKET.DestinationAddress]

        cmp     eax, 0xffffffff

        je      @f

        mov     ecx, [stack_ip]

        and     eax, [subnet_mask]

        and     ecx, [subnet_mask]

        cmp     eax, ecx

        jne     .dump.2

        mov     eax, [ebx + IP_PACKET.DestinationAddress]

        or      eax, [subnet_mask]

        cmp     eax, 0xffffffff

        jne     .dump.2

  @@:

        mov     al, [ebx + IP_PACKET.VersionAndIHL]

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

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

;        DEBUGF  1, "K : ip_rx - ihl: %x - 05\n", al

        jnz     .dump.3 ;then dump it

;        DEBUGF  1, "K : ip_rx - ttl: %x - 00\n", [ebx + IP_PACKET.TimeToLive]:2

        cmp     [ebx + IP_PACKET.TimeToLive], 0

        je      .dump.4 ;if TTL==0 then dump it

        mov     ax, [ebx + IP_PACKET.FlagsAndFragmentOffset]

        and     ax, 0xFFBF;get flags

;        DEBUGF  1, "K : ip_rx - flags: %x - 0000\n", ax

        cmp     ax, 0    ;if some flags was set then we dump this packet

        jnz     .dump.5    ;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.6          ;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.1:

        DEBUGF  1, "K : ip_rx - dumped (checksum: 0x%x-0x%x)\n", dx, ax

        jmp     .dump.x

  .dump.2:

        DEBUGF  1, "K : ip_rx - dumped (ip: %u.%u.%u.%u)\n", [ebx + IP_PACKET.DestinationAddress + 0]:1, [ebx + IP_PACKET.DestinationAddress + 1]:1, [ebx + IP_PACKET.DestinationAddress + 2]:1, [ebx + IP_PACKET.DestinationAddress + 3]:1

        jmp     .dump.x

  .dump.3:

        DEBUGF  1, "K : ip_rx - dumped (ihl: %u)\n", al

        jmp     .dump.x

  .dump.4:

        DEBUGF  1, "K : ip_rx - dumped (ttl: %u)\n", [ebx + IP_PACKET.TimeToLive]

        jmp     .dump.x

  .dump.5:

        DEBUGF  1, "K : ip_rx - dumped (flags: 0x%x)\n", ax

        jmp     .dump.x

  .dump.6:

        DEBUGF  1, "K : ip_rx - dumped (proto: %u)\n", [ebx + IP_PACKET.Protocol]:1

  .dump.x:

        inc     dword[dumped_rx_count]

        mov     eax, [buffer_number]

        call    freeBuff

  .exit:

        ret

endp