Subversion Repositories Kolibri OS

;

; Automated dhcp client

;

; v 1.1

;

; by the hidden player

;

DEBUG equ 1

TIMEOUT equ 60 ; in seconds

use32

	       org    0x0

	       db     'MENUET01'	      ; 8 byte id

	       dd     0x01		      ; header version

	       dd     START		      ; start of code

	       dd     IM_END		      ; size of image

	       dd     I_END		      ; memory for app

	       dd     I_END		      ; esp

	       dd     0x0 , 0x0 	      ; I_Param , I_Icon

include 'macros.inc'

if DEBUG = 1

include 'debug.inc'

end if

START:				; start of execution

    mov     eax,40		   ; Report events

    mov     ebx,10000000b	   ; Only Stack

    int     0x40

    mov     eax,52		   ; first, enable the stack

    mov     ebx,2

    mov     ecx,0x00000383

    int     0x40

if DEBUG = 1

    newline

    dps  "DHCP: Stack Initialized"

    newline

end if

    mov     eax, 53		   ; then, read in the status

    mov     ebx, 255

    mov     ecx, 6

    int     0x40

    cmp     eax,0		   ; if eax is zero, no driver was found

    jne     @f

if DEBUG = 1

    dps  "DHCP: No Card detected"

    newline

end if

    jmp  close

   @@:

if DEBUG = 1

    dps  "DHCP: Detected card: "

    dph  eax

    newline

end if

    ; now that the stack is running, lets start the dhcp request

    ; First, open socket

    mov     eax, 53

    mov     ebx, 0

    mov     ecx, 68		    ; local port dhcp client

    mov     edx, 67		    ; remote port - dhcp server

    mov     esi, -1		    ; broadcast

    int     0x40

    mov     [socketNum], eax

if DEBUG = 1

    dps   "DHCP: Socket opened: "

    dpd   eax

    newline

end if

    ; Setup the first msg we will send

    mov     byte [dhcpMsgType], 0x01 ; DHCP discover

    mov     dword [dhcpLease], esi   ; esi is still -1 (-1 = forever)

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

;   Function

;      buildRequest

;

;   Description

;      Creates a DHCP request packet.

;

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

buildRequest:

    ; Clear dhcpMsg to all zeros

    xor     eax,eax

    mov     edi,dhcpMsg

    mov     ecx,512

    cld

    rep     stosb

    mov     edx, dhcpMsg

    mov     [edx], byte 0x01		    ; Boot request

    mov     [edx+1], byte 0x01		    ; Ethernet

    mov     [edx+2], byte 0x06		    ; Ethernet h/w len

    mov     [edx+4], dword 0x11223344	    ; xid

    mov     [edx+10], byte 0x80 	    ; broadcast flag set

    mov     [edx+236], dword 0x63538263     ; magic number

    ; option DHCP msg type

    mov     [edx+240], word 0x0135

    mov     al, [dhcpMsgType]

    mov     [edx+240+2], al

    ; option Lease time = infinity

    mov     [edx+240+3], word 0x0433

    mov     eax, [dhcpLease]

    mov     [edx+240+5], eax

;    ; option requested IP address

    mov     [edx+240+9], word 0x0432

;    mov     eax, [dhcpClientIP]

;    mov     [edx+240+11], eax

    ; option request list

    mov     [edx+240+15], word 0x0437

    mov     [edx+240+17], dword 0x0f060301

    ; Check which msg we are sending

    cmp     [dhcpMsgType], byte 0x01

    jne     br001

    ; "Discover" options

    ; end of options marker

    mov     [edx+240+21], byte 0xff

    mov     [dhcpMsgLen], dword 262

    jmp     ctr000

br001:

    ; "Request" options

    ; server IP

    mov     [edx+240+21], word 0x0436

    mov     eax, [dhcpServerIP]

    mov     [edx+240+23], eax

    ; end of options marker

    mov     [edx+240+27], byte 0xff

    mov     [dhcpMsgLen], dword 268

ctr000:

    ; write to socket ( send broadcast request )

    mov     eax, 53

    mov     ebx, 4

    mov     ecx, [socketNum]

    mov     edx, [dhcpMsgLen]

    mov     esi, dhcpMsg

    int     0x40

    ; Setup the DHCP buffer to receive response

    mov     eax, dhcpMsg

    mov     [dhcpMsgLen], eax	   ; Used as a pointer to the data

    ; now, we wait for data from remote

wait_for_data:

    mov     eax,23		   ; wait here for event   NOTE a TIME-OUT should be placed here

    mov     ebx,TIMEOUT*100

    int     0x40

    ; Any data in the UDP receive buffer?

    mov     eax, 53

    mov     ebx, 2

    mov     ecx, [socketNum]

    int     0x40

    cmp     eax, 0

    jne     ctr002

if DEBUG = 1

    dps  "DHCP: Timeout!"

    newline

end if

    jmp    close

    ; we have data - this will be the response

ctr002:

    mov     eax, 53

    mov     ebx, 3

    mov     ecx, [socketNum]

    int     0x40		; read byte - block (high byte)

    ; Store the data in the response buffer

    mov     eax, [dhcpMsgLen]

    mov     [eax], bl

    inc     dword [dhcpMsgLen]

    mov     eax, 53

    mov     ebx, 2

    mov     ecx, [socketNum]

    int     0x40		; any more data?

    cmp     eax, 0

    jne     ctr002		; yes, so get it

    ; depending on which msg we sent, handle the response

    ; accordingly.

    ; If the response is to a dhcp discover, then:

    ;  1) If response is DHCP OFFER then

    ;  1.1) record server IP, lease time & IP address.

    ;  1.2) send a request packet

    ;  2) else exit ( display error )

    ; If the response is to a dhcp request, then:

    ;  1) If the response is DHCP ACK then

    ;  1.1) extract the DNS & subnet fields. Set them in the stack

    ;  2) else exit ( display error )

    cmp     [dhcpMsgType], byte 0x01	; did we send a discover?

    je	    discover

    cmp     [dhcpMsgType], byte 0x03	; did we send a request?

    je	    request

    ; should never get here - we only send discover or request

    jmp     close

discover:

    call    parseResponse

    ; Was the response an offer? It should be

    cmp     [dhcpMsgType], byte 0x02

    jne     close		   ; NO - so quit

    ; send request

    mov     [dhcpMsgType], byte 0x03 ; DHCP request

    jmp     buildRequest

request:

    call    parseResponse

    ; Was the response an ACK? It should be

    cmp     [dhcpMsgType], byte 0x05

    jne     close		   ; NO - so quit

close:

    ; close socket

    mov     eax, 53

    mov     ebx, 1

    mov     ecx, [socketNum]

    int     0x40

if DEBUG = 1

    dps  "DHCP: Exiting"

    newline

end if

    mov     eax,-1		   ; at last, exit

    int     0x40

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

;   Function

;      parseResponse

;

;   Description

;      extracts the fields ( client IP address and options ) from

;      a DHCP response

;      The values go into

;       dhcpMsgType,dhcpLease,dhcpClientIP,dhcpServerIP,

;       dhcpDNSIP, dhcpSubnet

;      The message is stored in dhcpMsg

;

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

parseResponse:

if DEBUG = 1

    dps  "DHCP: Data received, parsing response"

    newline

end if

    mov     edx, dhcpMsg

    pusha

    mov     eax,52	    ; Set Client IP

    mov     ebx,3

    mov     ecx, [edx+16]

    int     0x40

if DEBUG = 1

    dps  "DHCP: Client: "

    xor   esi,esi

   .loop:

    pusha

    movzx eax,byte[edx+esi+16]

    call  debug_outdec

    popa

    inc   esi

    cmp   esi,4

    jne   .loop

    newline

end if

    popa

    ; Scan options

    add     edx, 240	    ; Point to first option

pr001:

    ; Get option id

    mov     al, [edx]

    cmp     al, 0xff	    ; End of options?

    je	    pr_exit

    cmp     al, 53	    ; Msg type is a single byte option

    jne     pr002

    mov     al, [edx+2]

    mov     [dhcpMsgType], al

    add     edx, 3

    jmp     pr001	    ; Get next option

pr002:

    ; All other (accepted) options are 4 bytes in length

    inc     edx

    movzx   ecx, byte [edx]

    inc     edx 	    ; point to data

    cmp     al, 54	    ; server id

    jne     pr0021

    mov     eax, [edx]	    ; All options are 4 bytes, so get it

    mov     [dhcpServerIP], eax

    jmp     pr003

pr0021:

    cmp     al, 51	    ; lease

    jne     pr0022

if DEBUG = 1

    pusha

    dps  "DHCP: lease:  "

    cmp  dword[edx],-1

    jne  no_lease_forever

    dps  "forever"

    jmp  lease_newline

   no_lease_forever:

    dpd  [edx]

   lease_newline:

    newline

    popa

end if

    jmp     pr003

pr0022:

    cmp     al, 1	    ; subnet mask

    jne     pr0023

    pusha

    mov     eax,52

    mov     ebx,12

    mov     ecx,[edx]

    int     0x40

if DEBUG = 1

    dps  "DHCP: Subnet: "

    xor   esi,esi

   .loop:

    pusha

    movzx eax,byte[edx+esi]

    call  debug_outdec

    popa

    inc   esi

    cmp   esi,4

    jne   .loop

    newline

end if

    popa

    jmp     pr003

pr0023:

    cmp     al, 6	    ; dns ip

    jne     pr0024

    pusha

    mov     eax,52

    mov     ebx,14

    mov     ecx,[edx]

    int     0x40

if DEBUG = 1

    dps  "DHCP: DNS IP: "

    xor   esi,esi

   .loop:

    pusha

    movzx eax,byte[edx+esi]

    call  debug_outdec

    popa

    inc   esi

    cmp   esi,4

    jne   .loop

    newline

end if

    popa

pr0024:

    cmp     al, 3	    ; gateway ip

    jne     pr003

    pusha

    mov     eax,52

    mov     ebx,11

    mov     ecx,[edx]

    int     0x40

if DEBUG = 1

    dps  "DHCP: Gateway:"

    xor   esi,esi

   .loop:

    pusha

    movzx eax,byte[edx+esi]

    call  debug_outdec

    popa

    inc   esi

    cmp   esi,4

    jne   .loop

    newline

end if

    popa

pr003:

    add     edx, ecx

    jmp     pr001

pr_exit:

if DEBUG = 1

    dps  "DHCP: Done"

    newline

end if

    jmp close

; DATA AREA

IM_END:

dhcpMsgType:	db  0

dhcpLease:	dd  0

;dhcpClientIP:   dd  0

dhcpServerIP:	dd  0

dhcpMsgLen:	dd  0

socketNum:	dd  0xFFFF

dhcpMsg:	rb  512

I_END: