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

;;

;;  ARP.INC

;;

;;  Address Resolution Protocol

;;

;;  Last revision: 10.11.2006

;;

;;  This file contains the following:

;;   arp_table_manager - Manages an ARPTable

;;   arp_request - Sends an ARP request on the ethernet

;;   arp_handler - Called when an ARP packet is received

;;

;;  Changes history:

;;   22.09.2003 - [Mike Hibbett] : mikeh@oceanfree.net

;;   11.11.2006 - [Johnny_B] and [smb]

;;

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

ARP_NO_ENTRY                equ  0

ARP_VALID_MAPPING           equ  1

ARP_AWAITING_RESPONSE       equ  2

ARP_RESPONSE_TIMEOUT        equ  3

struc ARP_ENTRY     ;=14 bytes

{  .IP       dd  ?  ;+00

   .MAC      dp  ?  ;+04

   .Status   dw  ?  ;+10

   .TTL      dw  ?  ;+12 : ( in seconds )

}

virtual at 0

  ARP_ENTRY ARP_ENTRY

end virtual

; The TTL field is decremented every second, and is deleted when it

; reaches 0. It is refreshed every time a packet is received

; If the TTL field is 0xFFFF it is a static entry and is never deleted

; The status field can be the following values:

; 0x0000  entry not used

; 0x0001  entry holds a valid mapping

; 0x0002  entry contains an IP address, awaiting ARP response

; 0x0003  No response received to ARP request.

; The last status value is provided to allow the network layer to delete

; a packet that is queued awaiting an ARP response

; The follow is the ARP Table.

; This table must be manually updated and the kernel recompilied if

; changes are made to it.

; Empty entries are filled with zeros

ARP_ENTRY_SIZE              equ     14          ; Number of bytes per entry

ARP_TABLE_SIZE              equ     20          ; Size of table

ARP_TABLE_ENTRIES           equ     0           ; Number of static entries in the table

;TO ADD A STATIC ENTRY, DONT FORGET, PUT "ARPTable" from "uglobal" to "iglobal"!!!

;AND ALSO - IP and MAC have net byte-order, BUT STATUS AND TTL HAVE A MIRROR BYTE-ORDER!!!

uglobal

  ARPTable:

;example, static entry ->  db  11,22,33,44, 0x11,0x22,0x33,0x44,0x55,0x66, 0x01,0x00, 0xFF,0xFF

  times ( ARP_TABLE_SIZE - ARP_TABLE_ENTRIES ) * ARP_ENTRY_SIZE  db 0

endg

iglobal

  NumARP:        dd    ARP_TABLE_ENTRIES

  ARPTable_ptr   dd    ARPTable   ;pointer to ARPTable

endg

ARP_REQ_OPCODE              equ     0x0100  ;request

ARP_REP_OPCODE              equ     0x0200  ;reply

struc ARP_PACKET

{  .HardwareType dw   ?  ;+00

   .ProtocolType dw   ?  ;+02

   .HardwareSize db   ?  ;+04

   .ProtocolSize db   ?  ;+05

   .Opcode       dw   ?  ;+06

   .SenderMAC    dp   ?  ;+08

   .SenderIP     dd   ?  ;+14

   .TargetMAC    dp   ?  ;+18

   .TargetIP     dd   ?  ;+24

}

virtual at 0

  ARP_PACKET ARP_PACKET

end virtual

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

;   Function

;      arp_table_manager  [by Johnny_B]

;

;   Description

;     Does a most required operations with ARP-table

;  IN:

;   Operation: see Opcode's constants below

;       Index: Index of entry in the ARP-table

;       Extra: Extra parameter for some Opcodes

;  OUT:

;   EAX = Returned value depends on opcodes, more detailed see below

;

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

;Opcode's constants

ARP_TABLE_ADD                 equ  1

ARP_TABLE_DEL                 equ  2

ARP_TABLE_GET                 equ  3

ARP_TABLE_GET_ENTRIES_NUMBER  equ  4

ARP_TABLE_IP_TO_MAC           equ  5

ARP_TABLE_TIMER               equ  6

;Index's constants

EXTRA_IS_ARP_PACKET_PTR  equ  0   ;if Extra contain pointer to ARP_PACKET

EXTRA_IS_ARP_ENTRY_PTR   equ  -1  ;if Extra contain pointer to ARP_ENTRY

align 4

proc arp_table_manager stdcall uses ebx esi edi ecx edx,\

    Opcode:DWORD,Index:DWORD,Extra:DWORD

    mov     ebx, dword[ARPTable_ptr]   ;ARPTable base

    mov     ecx, dword[NumARP]         ;ARP-entries counter

    mov     eax, dword[Opcode]

    cmp     eax, ARP_TABLE_TIMER

    je      .timer

    cmp     eax, ARP_TABLE_ADD

    je      .add

    cmp     eax, ARP_TABLE_DEL

    je      .del

    cmp     eax, ARP_TABLE_GET

    je      .get

    cmp     eax, ARP_TABLE_IP_TO_MAC

    je      .ip_to_mac

    cmp     eax, ARP_TABLE_GET_ENTRIES_NUMBER

    je      .get_entries_number

    jmp     .exit     ;if unknown opcode

;;BEGIN TIMER

;;Description: it must be callback every second. It is responsible for removing expired routes.

;;IN:   Operation: ARP_TABLE_TIMER

;;      Index: must be zero

;;      Extra: must be zero

;;OUT:

;;  EAX=not defined

;;

.timer:

    test    ecx, ecx

    jz      .exit    ;if NumARP=0 nothing to do

    sub     ecx, ARP_TABLE_ENTRIES  ;ecx=dynamic entries number

    jz      .exit    ;if NumARP=number of static entries then exit

    add     ebx, ARP_TABLE_ENTRIES*ARP_ENTRY_SIZE  ;ebx=dynamic entries base

  .timer_loop:

    movsx   esi, word [ebx + ARP_ENTRY.TTL]

    cmp     esi, 0xFFFFFFFF

    je      .timer_loop_end  ;if TTL==0xFFFF then it's static entry

    test    esi, esi

    jnz     .timer_loop_end_with_dec  ;if TTL!=0

    ; Ok, TTL is 0

    ;if Status==AWAITING_RESPONSE and TTL==0

    ;then we have to change it to ARP_RESPONSE_TIMEOUT

    cmp     word [ebx + ARP_ENTRY.Status], ARP_AWAITING_RESPONSE

    jne     @f

    mov     word [ebx + ARP_ENTRY.Status], ARP_RESPONSE_TIMEOUT

    mov     word [ebx + ARP_ENTRY.TTL], word 0x000A   ;10 sec

    jmp     .timer_loop_end

  @@:

    ;if TTL==0 and Status==VALID_MAPPING, we have to delete it

    ;if TTL==0 and Status==RESPONSE_TIMEOUT, delete too

    mov     esi, dword[NumARP]

    sub     esi, ecx          ;esi=index of entry, will be deleted

    stdcall arp_table_manager,ARP_TABLE_DEL,esi,0 ;opcode,index,extra

    jmp     .timer_loop_end

  .timer_loop_end_with_dec:

    dec     word [ebx + ARP_ENTRY.TTL]  ;decrease TTL

  .timer_loop_end:

    add     ebx, ARP_ENTRY_SIZE

    loop    .timer_loop

    jmp     .exit

;;END TIMER

;;BEGIN ADD

;;Description: it adds an entry in the table. If ARP-table already

;;             contains same IP, it will be updated.

;;IN:   Operation: ARP_TABLE_ADD

;;      Index: specifies what contains Extra-parameter

;;      Extra: if Index==EXTRA_IS_ARP_PACKET_PTR,

;;             then Extra contains pointer to ARP_PACKET,

;;             otherwise Extra contains pointer to ARP_ENTRY

;;OUT:

;;  EAX=index of entry, that has been added

;;

.add:

    sub     esp, ARP_ENTRY_SIZE   ;Allocate ARP_ENTRY_SIZE byte in stack

    mov     esi, [Extra]   ;pointer

    mov     edi, [Index]   ;opcode

    cmp     edi, EXTRA_IS_ARP_PACKET_PTR

    je      .arp_packet_to_entry ;if Extra contain ptr to ARP_PACKET and we have to form arp-entry

                                 ;else it contain ptr to arp-entry

    cld

          ; esi already has been loaded

    mov     edi, esp      ;ebx + eax=ARPTable_base + ARP-entry_base(where we will add)

    mov     ecx,ARP_ENTRY_SIZE/2  ;ARP_ENTRY_SIZE must be even number!!!

    rep     movsw    ;copy

    jmp     .search

  .arp_packet_to_entry:

    mov     edx, dword[esi + ARP_PACKET.SenderIP] ;esi=base of ARP_PACKET

    mov     [esp + ARP_ENTRY.IP], edx

    cld

    lea     esi, [esi + ARP_PACKET.SenderMAC]

    lea     edi, [esp + ARP_ENTRY.MAC]

    movsd

    movsw

    mov     word[esp + ARP_ENTRY.Status], ARP_VALID_MAPPING  ; specify the type - a valid entry

    mov     word[esp + ARP_ENTRY.TTL], 0x0E10    ; = 1 hour

  .search:

    mov     edx, dword[esp + ARP_ENTRY.IP]  ;edx=IP-address, which we'll search

    mov     ecx, dword[NumARP]              ;ecx=ARP-entries counter

    jecxz   .add_to_end                     ;if ARP-entries number == 0

    imul    eax, ecx, ARP_ENTRY_SIZE        ;eax=current table size(in bytes)

  @@:

    sub     eax, ARP_ENTRY_SIZE

    cmp     dword[ebx + eax + ARP_ENTRY.IP], edx

    loopnz  @b

    jz      .replace       ; found, replace existing entry, ptr to it is in eax

  .add_to_end:

    ;else add to end

    or      eax,-1    ;set eax=0xFFFFFFFF if adding is impossible

    mov     ecx, dword[NumARP]

    cmp     ecx, ARP_TABLE_SIZE

    je      .add_exit   ;if arp-entries number is equal to arp-table maxsize

    imul    eax, dword[NumARP], ARP_ENTRY_SIZE ;eax=ptr to end of ARPTable

    inc     dword [NumARP]    ;increase ARP-entries counter

  .replace:

    cld

    mov     esi, esp              ;esp=base of ARP-entry, that will be added

    lea     edi, [ebx + eax]      ;ebx + eax=ARPTable_base + ARP-entry_base(where we will add)

    mov     ecx,ARP_ENTRY_SIZE/2  ;ARP_ENTRY_SIZE must be even number!!!

    rep     movsw

    mov     ecx, ARP_ENTRY_SIZE

    xor     edx, edx  ;"div" takes operand from EDX:EAX

    div     ecx       ;eax=index of entry, which has been added

.add_exit:

    add     esp, ARP_ENTRY_SIZE   ;free stack

    jmp     .exit

;;END ADD

;;BEGIN DEL

;;Description: it deletes an entry in the table.

;;IN:   Operation: ARP_TABLE_DEL

;;      Index: index of entry, that should be deleted

;;      Extra: must be zero

;;OUT:

;;  EAX=not defined

;;

.del:

    mov     esi, [Index]

    imul    esi, ARP_ENTRY_SIZE

    mov     ecx, (ARP_TABLE_SIZE - 1) * ARP_ENTRY_SIZE

    sub     ecx, esi

    lea     edi, [ebx + esi]            ;edi=ptr to entry that should be deleted

    lea     esi, [edi + ARP_ENTRY_SIZE] ;esi=ptr to next entry

    shr     ecx,1      ;ecx/2 => ARP_ENTRY_SIZE MUST BE EVEN NUMBER!

    cld

    rep     movsw

    dec     dword[NumARP] ;decrease arp-entries counter

    jmp     .exit

;;END DEL

;;BEGIN GET

;;Description: it reads an entry of table into buffer.

;;IN:   Operation: ARP_TABLE_GET

;;      Index: index of entry, that should be read

;;      Extra: pointer to buffer for reading(size must be equal to ARP_ENTRY_SIZE)

;;OUT:

;;  EAX=not defined

;;

.get:

    mov     esi, [Index]

    imul    esi, ARP_ENTRY_SIZE   ;esi=ptr to required ARP_ENTRY

    mov     edi, [Extra]          ;edi=buffer for reading

    mov     ecx, ARP_ENTRY_SIZE/2 ; must be even number!!!

    cld

    rep     movsw

    jmp     .exit

;;END GET

;;BEGIN IP_TO_MAC

;;Description: it gets an IP from Index, scans each entry in the table and writes

;;             MAC, that relates to specified IP, into buffer specified in Extra.

;;             And if it cannot find an IP-address in the table, it does an ARP-request of that.

;;IN:   Operation: ARP_TABLE_IP_TO_MAC

;;      Index: IP that should be transformed into MAC

;;      Extra: pointer to buffer where will be written the MAC-address.

;;OUT:

;;  EAX=ARP table entry status code.

;;      If EAX==ARP_NO_ENTRY, IP isn't found in the table and we have sent the request.

;;      If EAX==ARP_AWAITING_RESPONSE, we wait the response from remote system.

;;      If EAX==ARP_RESPONSE_TIMEOUT, remote system not responds too long.

;;      If EAX==ARP_VALID_MAPPING, all is ok, we've got a true MAC.

;;

;;  If MAC will equal to a zero, in the buffer. It means, that IP-address was not yet

;;  resolved, or that doesn't exist. I recommend you, to do at most 3-5 calls of this

;;  function with 1sec delay. sure, only if it not return a valid MAC after a first call.

;;

.ip_to_mac:

    xor     eax, eax

    mov     edi, dword[Extra]

    cld

    stosd

    stosw

    cmp     dword[NumARP], 0

    je      .ip_to_mac_send_request ;if ARP-table not contain an entries, we have to request IP.

                                    ;EAX will be containing a zero, it's equal to ARP_NO_ENTRY

    ; first, check destination IP to see if it is on 'this' network.

    ; The test is:

    ; if ( destIP & subnet_mask == stack_ip & subnet_mask )

    ;   destination is local

    ; else

    ;  destination is remote, so pass to gateway

    mov     eax, [Index]       ;eax=required IP

    mov     esi, eax

    and     esi, [subnet_mask]

    mov     ecx, [stack_ip]

    and     ecx, [subnet_mask]

    cmp     esi, ecx

    je      @f        ;if we and target IP are located in the same network

    mov     eax, [gateway_ip]

  @@:

    mov     ecx, dword[NumARP]

    imul    esi, ecx, ARP_ENTRY_SIZE  ;esi=current ARP-table size

  @@:

    sub     esi, ARP_ENTRY_SIZE

    cmp     [ebx + esi], eax         ; ebx=ARPTable base

    loopnz  @b                       ; Return back if non match

    jnz     .ip_to_mac_send_request  ; and request IP->MAC if none found in the table

    ; Return the entry status in eax

    movzx   eax, word[ebx + esi + ARP_ENTRY.Status]

    ; esi holds index

    cld

    lea     esi, [ebx + esi + ARP_ENTRY.MAC]

    mov     edi, [Extra]   ;edi=ptr to buffer for write MAC

    movsd

    movsw

    jmp     .exit

  .ip_to_mac_send_request:

    stdcall arp_request,[Index],stack_ip,node_addr  ;TargetIP,SenderIP_ptr,SenderMAC_ptr

    mov     eax, ARP_NO_ENTRY

    jmp     .exit

;;END IP_TO_MAC

;;BEGIN GET_ENTRIES_NUMBER

;;Description: returns an ARP-entries number in the ARPTable

;;IN:   Operation: ARP_TABLE_GET_ENTRIES_NUMBER

;;      Index: must be zero

;;      Extra: must be zero

;;OUT:

;;  EAX=ARP-entries number in the ARPTable

  .get_entries_number:

    mov     eax, dword[NumARP]

    jmp     .exit

;;END GET_ENTRIES_NUMBER

.exit:

    ret

endp

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

;   Function

;      arp_handler

;

;   Description

;      Called when an ARP packet is received on the ethernet

;      Header + Data is in Ether_buffer[]

;       It looks to see if the packet is a request to resolve this Hosts

;       IP address. If it is, send the ARP reply packet.

;      This Hosts IP address is in dword [stack_ip]  ( in network format )

;       This Hosts MAC address is in node_addr[6]

;      All registers may be destroyed

;

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

arp_handler:

    ; Is this a REQUEST?

    ; Is this a request for My Host IP

    ; Yes - So construct a response message.

    ; Send this message to the ethernet card for transmission

    stdcall arp_table_manager,ARP_TABLE_ADD,EXTRA_IS_ARP_PACKET_PTR,ETH_FRAME.Data + ARP_PACKET

    inc     dword[arp_rx_count] ;increase ARP-packets counter

    cmp     word[ETH_FRAME.Data + ARP_PACKET.Opcode], ARP_REQ_OPCODE  ; Is this a request packet?

    jne     .exit            ; No - so exit

    mov     eax, [stack_ip]

    cmp     eax, dword[ETH_FRAME.Data + ARP_PACKET.TargetIP]         ; Is it looking for my IP address?

    jne     .exit            ; No - so quit now

    ; OK, it is a request for my MAC address. Build the frame and send it

    ; We can reuse the packet.

    mov     word[ETH_FRAME.Data + ARP_PACKET.Opcode], ARP_REP_OPCODE

    cld

    mov     esi, ETH_FRAME.Data + ARP_PACKET.SenderMAC

    mov     edi, ETH_FRAME.Data + ARP_PACKET.TargetMAC

    movsd

    movsw

    mov     esi, ETH_FRAME.Data + ARP_PACKET.SenderIP

    mov     edi, ETH_FRAME.Data + ARP_PACKET.TargetIP

    movsd

    mov     esi, node_addr

    mov     edi, ETH_FRAME.Data + ARP_PACKET.SenderMAC

    movsd

    movsw

    mov     esi, stack_ip

    mov     edi, ETH_FRAME.Data + ARP_PACKET.SenderIP

    movsd

    ; Now, send it!

    mov     edi, ETH_FRAME.Data + ARP_PACKET.TargetMAC   ;ptr to destination MAC address

    mov     bx, ETHER_ARP               ;type of protocol

    mov     ecx, 28                     ;data size

    mov     esi, ETH_FRAME.Data + ARP_PACKET             ;ptr to data

    call    dword [drvr_transmit]       ;transmit packet

  .exit:

    ret

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

;   Function

;      arp_request  [by Johnny_B]

;

;   Description

;      Sends an ARP request on the ethernet

;   IN:

;     TargetIP      : requested IP address

;     SenderIP_ptr  : POINTER to sender's IP address(our system's address)

;     SenderMAC_ptr : POINTER to sender's MAC address(our system's address)

;   OUT:

;     EAX=0 (if all is ok), otherwise EAX is not defined

;

;      EBX,ESI,EDI will be saved

;

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

proc arp_request stdcall uses ebx esi edi,\

    TargetIP:DWORD, SenderIP_ptr:DWORD, SenderMAC_ptr:DWORD

    inc     dword[arp_tx_count]  ; increase counter

    sub     esp, 28  ; allocate memory for ARP_PACKET

    mov     word[esp + ARP_PACKET.HardwareType],0x0100 ;Ethernet

    mov     word[esp + ARP_PACKET.ProtocolType],0x0008 ;IP

    mov     byte[esp + ARP_PACKET.HardwareSize],0x06   ;MAC-addr length

    mov     byte[esp + ARP_PACKET.ProtocolSize],0x04   ;IP-addr length

    mov     word[esp + ARP_PACKET.Opcode],0x0100       ;Request

    cld

    mov     esi,[SenderMAC_ptr]

    lea     edi,[esp + ARP_PACKET.SenderMAC]       ;Our MAC-addr

    movsd

    movsw

    mov     esi,[SenderIP_ptr]

    lea     edi,[esp + ARP_PACKET.SenderIP]        ;Our IP-addr

    movsd

    xor     eax, eax

    lea     edi, [esp + ARP_PACKET.TargetMAC]      ;Required MAC-addr(zeroed)

    stosd

    stosw

    mov     esi, dword[TargetIP]

    mov     dword[esp + ARP_PACKET.TargetIP],esi   ;Required IP-addr(we get it as function parameter)

    ; Now, send it!

    mov     edi, broadcast_add     ; Pointer to 48 bit destination address

    mov     bx, ETHER_ARP          ; Type of packet

    mov     ecx, 28                ; size of packet

    lea     esi, [esp + ARP_PACKET]; pointer to packet data

    call    dword [drvr_transmit]  ; Call the drivers transmit function

    add     esp, 28  ; free memory, allocated before for ARP_PACKET

    ; Add an entry in the ARP table, awaiting response

    sub     esp, ARP_ENTRY_SIZE    ;allocate memory for ARP-entry

    mov     esi, dword[TargetIP]

    mov     dword[esp + ARP_ENTRY.IP],esi

    lea     edi, [esp + ARP_ENTRY.MAC]

    xor     eax, eax

    stosd

    stosw

    mov     word[esp + ARP_ENTRY.Status], ARP_AWAITING_RESPONSE

    mov     word[esp + ARP_ENTRY.TTL], 0x000A  ; 10 seconds

    stdcall arp_table_manager,ARP_TABLE_ADD,EXTRA_IS_ARP_ENTRY_PTR,esp

    add     esp, ARP_ENTRY_SIZE  ; free memory

.exit:

    ret

endp