PC Press: Internet/PC_PRESS.ISO/software/dos/misc/inar-100.exe/SRC/PCROUTE/ARP.INC

Text File | 1995-05-21 | 16.8 KB | 505 lines

;;*****************************************************************************
;;                        arp.inc           arp.inc
;;*****************************************************************************
;;
;;  Copyright (C) 1989 Northwestern University, Vance Morrison
;;
;;
;; Permission to view, compile, and modify for LOCAL (intra-organization)
;; USE ONLY is hereby granted, provided that this copyright and permission
;; notice appear on all copies.  Any other use by permission only.
;;
;; Northwestern University makes no representations about the suitability
;; of this software for any purpose.  It is provided "as is" without expressed
;; or implied warranty.  See the copywrite notice file for complete details.
;;
;;*****************************************************************************
;;
;; arp.inc constains the DL_IP interface for ethernet.  This is the module
;; that handles the arp lookup need to support the DL_IP interface
;; (see dl_ip.inc for a description of the DL_IP interface)
;;
;; The functions provided by this file are
;;
;;   ARP_DECLARE name, ether
;;   ARP_DEFINE name, ip_address, ip_net, ip_mask
;;   ARP_DL_IP_R_READ name, code_label
;;   ARP_DL_IP_R_CONT_in_BX_CX_ES_const_BX_CX_DX_BP_SI_DI_ES name, ok
;;   ARP_DL_IP_RETURN name
;;   ARP_DL_IP_W_ACCESS_in_CX_out_DI_ES_const_CX_BP name, fail
;;   ARP_DL_IP_W_WRITE_in_AX_BX_CX_const_BP name, broadcast
;;   ARP_DL_IP_IS_BROADCAST_in_BX_ES_const_AX_BX_CX_DX_BP_DI_ES name
;;   ARP_DL_IP_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES name
;;
;;  Variables Provided by this module (READ ONLY!!!!)
;;
;;      arp_&name&_declared         1 if this data structure is declared
;;      dl_ip_&name&_ip             the IP address
;;      dl_ip_&name&_mask           the network mask
;;      dl_ip_&name&_net            the network
;;      dl_ip_&name&_broad          the network broadcast address
;;      dl_ip_&name&_gbroad         the global network broadcast address
;;      dl_ip_&name&_flags          A word exclusively for IP use
;;      dl_ip_&name&_mtu            The maximum transmition unit
;;      dl_ip_&name&_metric         The interface metric
;;      dl_ip_&name&_id             The route id
;;      dl_ip_&name&_haddr          The hardware address
;;
;;*****************************************************************************


;;*****************************************************************************
;; data storage needed by this module

arp_data STRUC
    arp_broadcast        DW 3 dup (0)
    arp_write_off        DW 0               ;; offset and seg for
    arp_write_seg        DW 0               ;; the write buffer
arp_data ENDS


;;*****************************************************************************
;;   ARP_DECLARE name, ether
;;       creates a new data link  object.  'name' is the name of this new
;;       object.  'ether' is the name of the ethernet to that will provide
;;       the low level services this module will need.
;;
ARP_DECLARE MACRO name, ether
    .errb <name>
    .errb <ether>

    .DATA
    arp_&name&_declared =  1
    arp_&name&_ether =  ether
    arp_&name&_arptab =  (100*name+1)
    dl_ip_&name&_mtu = 1500
    dl_ip_&name&_haddr =  eth_ðer&_address

    global dl_ip_&name&_ip:dword
    global dl_ip_&name&_mask:dword
    global dl_ip_&name&_net:dword
    global dl_ip_&name&_broad:dword
    global dl_ip_&name&_gbroad:dword
    global dl_ip_&name&_flags:word
    global dl_ip_&name&_metric:word
    global dl_ip_&name&_id:word
    global arp_&name&_data:arp_data
    global arp_&name&_real_dl_ip_w_write:near
    .CODE

    ARP_TAB_DECLARE %arp_&name&_arptab
ENDM


;;*****************************************************************************
;;   ARP_DEFINE name, ip_address, ip_net, ip_mask
;;      ARP_DEFINE declare all the things that have to be defined in
;;      every independantly assembled module.  DL_IP declares those
;;      things that need be be done only once (in particular memory allocation
;;      and initialzation code).  Every module including the one ARP_DEFINE
;;      is in) must have a DL_IP_DELCARE.   'ip_address' holds the IP address
;;      for this interface, 'ip_net' is the network and 'ip_mask' is the
;;      matching subnet mask.
;;
ARP_DEFINE MACRO name, ip_address, ip_net, ip_mask
    local around, arp_read_packet, zero_broad, zero_broad1
    local class_A, class_B, class_C
    .errb <ip_mask>

ifdef arp_&name&_declared
    .DATA
    dl_ip_&name&_ip    DD ?
    dl_ip_&name&_mask  DD ?
    dl_ip_&name&_net   DD ?
    dl_ip_&name&_broad DD ?
    dl_ip_&name&_gbroad DD ?
    dl_ip_&name&_flags DW ?
    dl_ip_&name&_metric DW ?
    dl_ip_&name&_id    DW ?

    arp_&name&_data  arp_data <>             ;; create storage needed

    .CODE
    jmp around
        arp_read_packet:
            ARP_PROCESS_PACKET_in_AX_BX_ES name
            ETH_R_RETURN %arp_&name&_ether
            ;; this does NOT fall through

        arp_&name&_real_dl_ip_w_write:
            ARP_REAL_DL_IP_W_WRITE_in_AX_BX_CX_const_BP name
            RET
    around:

    mov AX, word ptr ip_address                 ;; copy over params
    mov word ptr dl_ip_&name&_ip, AX
    mov AX, word ptr ip_address+2
    mov word ptr dl_ip_&name&_ip+2, AX

    mov AX, word ptr ip_net
    mov BX, word ptr ip_mask
    mov word ptr dl_ip_&name&_net, AX
    mov word ptr dl_ip_&name&_mask, BX

    test word ptr dl_ip_&name&_flags, ZERO_BROADCAST
    jnz zero_broad
        not BX
        or AX, BX
    zero_broad:
    mov word ptr dl_ip_&name&_broad, AX

    mov AX, word ptr ip_net+2
    mov BX, word ptr ip_mask+2
    mov word ptr dl_ip_&name&_net+2, AX
    mov word ptr dl_ip_&name&_mask+2, BX

    mov DL, AL
    xor DH, DH
    test word ptr dl_ip_&name&_flags, ZERO_BROADCAST
    jnz zero_broad1
        not BX
        or AX, BX
        mov DH, 0ffh
    zero_broad1:
    mov word ptr dl_ip_&name&_broad+2, AX

    mov AX, word ptr ip_net
    test AL, 80h
    jz class_A
    test AL, 40h
    jz class_B
    jmp class_C
    class_A:
        mov AH, DH
    class_B:
        mov DL, DH
    class_C:
    mov word ptr dl_ip_&name&_gbroad, AX
    mov word ptr dl_ip_&name&_gbroad+2, DX

    ARP_TAB_DEFINE %arp_&name&_arptab

    mov AX, DS                          ;; initialize the broadcast addr
    mov ES, AX
    mov DI, offset arp_&name&_data.arp_broadcast
    mov AX, 0FFFFh
    stosw
    stosw
    stosw

    mov AX, word ptr dl_ip_&name&_broad
    mov DX, word ptr dl_ip_&name&_broad+2
    mov BX, offset arp_&name&_data.arp_broadcast
    ARP_TAB_ADD_FIXED_in_AX_DX_BX_ES_out_SI_const_BX_DX_BP_DI_ES %arp_&name&_arptab
    mov AX, word ptr dl_ip_&name&_gbroad
    mov DX, word ptr dl_ip_&name&_gbroad+2
    ARP_TAB_ADD_FIXED_in_AX_DX_BX_ES_out_SI_const_BX_DX_BP_DI_ES %arp_&name&_arptab
    ;; start up the arp task
    ETH_R_READ %arp_&name&_ether, SWAPPED_ARP_TYPE, arp_read_packet
endif
ENDM


;;******************************************************************************
;;   DL_IP_R_READ name, code_label
;;       DL_IP_R_READ declares that the code starting at 'code_label'
;;       should be called whenever a IP packet is read.  BX:ES is initilized
;;       to the begining of the IP packet before 'macro_code' is called
;;       The code at 'code_label' should call ARP_DL_IP_R_RETURN when it
;;       is done processing the packet.
;;       This procedure can only be called once per 'name'
;;
ARP_DL_IP_R_READ MACRO name, code_label
    .errb <code_label>

    ETH_R_READ %arp_&name&_ether, SWAPPED_IP_TYPE, code_label
ENDM

;;******************************************************************************
;;   DL_IP_R_CONT_in_BX_CX_ES name, ok
;;       DL_IP_R_CONT determines if the packet returned by R_READ in BX:ES
;;       of length CX is continuous.  If it is it jumps to 'ok' otherwise
;;       it just returns
;;
ARP_DL_IP_R_CONT_in_BX_CX_ES_const_BX_CX_DX_BP_SI_DI_ES MACRO name, ok
    .errb <ok>

    ETH_R_CONT_in_BX_CX_ES_const_BX_CX_DX_BP_SI_DI_ES %arp_&name&_ether, ok
ENDM

;;******************************************************************************
;;   DL_IP_R_RETURN name
;;       DL_IP_R_RETURN should be executed by the READ routine to signal
;;       that it is done processing the packet.
;;
ARP_DL_IP_R_RETURN MACRO name
    .errb <name>

    ETH_R_RETURN %arp_&name&_ether
ENDM


;;******************************************************************************
;;   DL_IP_W_ACCESS_in_CX_out_DI_ES name, fail
;;       DL_IP_W_ACCESS returns a pointer to an output buffer for a IP
;;       packet.  The pointer is returned in DI:ES.  This routine may
;;       busy wait for a time, and after a reasonable attempt a buffer
;;       could not be had, it will jump to 'fail'
;;
ARP_DL_IP_W_ACCESS_in_CX_out_DI_ES_const_CX_BP MACRO name, fail
    .errb <name>
    .errb <fail>

    ETH_W_ACCESS_in_CX_out_DI_ES_const_BX_CX_BP %arp_&name&_ether, fail
    mov arp_&name&_data.arp_write_off, DI
    mov arp_&name&_data.arp_write_seg, ES
ENDM


;;******************************************************************************
;;   DL_IP_W_WRITE_in_AX_BX_CX name, broadcast
;;       DL_IP_W_WRITE actually signals the link layer to write a packet to the
;;       network.  The packet is assumed to be in the buffer returned by
;;       DL_IP_W_ACCESS.  CX is the length of the packet to send.
;;       AX_BX holds the IP address to send the packet to.
;;       if 'broadcast' is not blank, then the packet is written to the
;;       broadcast address.  AX:BX is ignored in this case
;;
ARP_DL_IP_W_WRITE_in_AX_BX_CX_const_BP MACRO name, broadcast
    ifb <broadcast>
        call arp_&name&_real_dl_ip_w_write
    else
        ARP_REAL_DL_IP_W_WRITE_in_AX_BX_CX_const_BP name, broadcast
    endif
ENDM

ARP_REAL_DL_IP_W_WRITE_in_AX_BX_CX_const_BP MACRO name, broadcast
    local send_packet
    .errb <name>

    push BP
    les DI, dword ptr arp_&name&_data.arp_write_off
    mov BP, SWAPPED_IP_TYPE
    ifb <broadcast>
        ARP_TAB_GET_in_AX_BX_out_SI_const_AX_BX_CX_BP_DI_ES %arp_&name&_arptab
        jz send_packet
            ARP_BUILD_REQUEST_in_AX_BX_DI_ES_const_AX_BX_DX_BP_ES name
            mov CX, size arp
            mov DI, word ptr arp_&name&_data.arp_write_off
            mov SI, offset arp_&name&_data.arp_broadcast
            mov BP, SWAPPED_ARP_TYPE
        send_packet:
    else
        mov SI, offset arp_&name&_data.arp_broadcast
    endif
    mov AX, BP
    pop BP
    ETH_W_WRITE_in_AX_CX_SI_DI_ES_const_BX_BP_ES %arp_&name&_ether
ENDM


;;******************************************************************************
;;   DL_IP_IS_BROADCAST_in_BX_ES name
;;      DL_IP_IS_BROADCAST_in_BX_ES determines if the packet pointed to
;;      by BX:ES is a broadcast and sets the zero flag if it is NOT a
;;      broadcast
;;
ARP_DL_IP_IS_BROADCAST_in_BX_ES_const_AX_BX_CX_DX_BP_DI_ES MACRO name
    .errb <name>
    ETH_IS_BROADCAST_in_BX_ES_const_AX_BX_CX_DX_BP_DI_ES %arp_&name&_ether
ENDM


;;******************************************************************************
;;   DL_IP_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES name
;;      DL_IP_COPY_in_CX_SI_DI_ES copys a packet from the input buffer (pointed
;;      to by SI and the segement register given in IF_DECLARE) to an output
;;      buffer (pointed to by DI and dest_reg) of length CX.   It assumes the
;;      output buffer is contiguous.  (and the caller shouldn't care if the
;;      input buffer is contiguous)  COPY updates the pointers SI and DI
;;      to the end of the packet, and COPY could be called again if CX is not
;;      the total packet length (Note that CX MUST be even if you care about
;;      SI, and DI being updated properly)
;;
;;
ARP_DL_IP_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES MACRO name
    .errb <name>
    ETH_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES %arp_&name&_ether
ENDM


;;******************************************************************************
;; ARP_PROCESS_PACKET_in_AX_BX_ES MACRO name
;;      ARP_PROCESS_PACKET is called when an ARP packet is received.  AX holds
;;      the ethernet type (SWAPPED_ARP_TYPE) and BX:ES points to the begining
;;      of the ARP packet
;;
ARP_PROCESS_PACKET_in_AX_BX_ES MACRO name
    local notarp, not_directly, forme, notme, pa_forme
    local save_seg
    .errb <name>

    .DATA
    save_seg DW ?

    .CODE
    mov AX, word ptr ES:[BX+arp_proto] ;; is it my IP address
    cmp word ptr AX, SWAPPED_IP_TYPE
    jne notarp
    mov AX, word ptr ES:[BX+arp_spa]
        mov DX, word ptr ES:[BX+arp_spa+2]
        add BX, arp_sha
        ARP_TAB_ADD_in_AX_DX_BX_ES_out_SI_const_BX_DX_BP_DI_ES %arp_&name&_arptab
        sub BX, arp_sha
        cmp byte ptr ES:[BX+arp_op+1], ARP_REQUEST
        jnz notme
        mov AX, word ptr ES:[BX+arp_tpa]
        mov DX, word ptr ES:[BX+arp_tpa+2]
        cmp AX, word ptr dl_ip_&name&_ip    ;; is it my IP address ?
        jne  not_directly
        cmp DX, word ptr dl_ip_&name&_ip+2
        je forme

        not_directly:
        ;; should I PROXY?
        test word ptr dl_ip_&name&_flags, ARP_PROXY_ARP
        jz notme
    mov BP, BX            ;; Save BX
    mov CX, SI            ;; Save SI
        xor SI, SI
        mov DI, SI
    mov BX, DX
    ROUTE_FIND_in_AX_BX_SI_DI_out_AX_BX_DX_const_CX_BP_ES %myip,pa_forme,notme
    cmp DL, name            ;; Is the destination on same
    je notme            ;; interface? then FORGET IT!
        pa_forme:
            mov BX, BP
            mov SI, CX
        forme:
            mov BP, SI                      ;; save SI
            mov SI, BX
            ARP_BUILD_REPLY_in_SI_ES_const_DX_BP_SI_ES name

            mov CX, size arp
            mov BX, SI                      ;; save SI
            mov word ptr save_seg, ES       ;; save ES
            ETH_W_ACCESS_in_CX_out_DI_ES_const_BX_CX_BP %arp_&name&_ether, notme
            mov SI, BX                      ;; restore SI

            mov BX, DI                      ;; save DI
            mov CX, size arp
            push DS
            mov DS, word ptr save_seg
            ETH_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES %arp_&name&_ether
            pop DS

            mov CX, size arp
            mov DI, BX                      ;; restore DI
            mov SI, BP                      ;; restore SI
            mov AX, SWAPPED_ARP_TYPE
            ETH_W_WRITE_in_AX_CX_SI_DI_ES_const_BX_BP_ES %arp_&name&_ether
        notme:
   notarp:
ENDM


;;******************************************************************************
;; arp related stuff.  these are for internal use only

ARP_REQUEST = 1
ARP_REPLY   = 2
SWAPPED_ARP_REQUEST = 100h
SWAPPED_ARP_REPLY   = 200h

ARP_ETHER_TYPE  = 1
SWAPPED_ARP_ETHER_TYPE = 100h

arp STRUC
    arp_hdr DW 1            ;; header type 1 = ETHERNET
    arp_proto DW 0
    arp_hln DB 6            ;; length of ethernet address
    arp_pln DB 4            ;; length of IP address
    arp_op  DW ARP_REPLY    ;; operation
    arp_sha DB 6 DUP (0)    ;; source hardware address
    arp_spa DB 4 DUP (0)    ;; source protocol address
    arp_tha DB 6 DUP (0)    ;; target hardware address
    arp_tpa DB 4 DUP (0)    ;; target protocol address
arp ENDS


;;******************************************************************************
;; ARP_BUILD_REQUEST_in_AX_BX_DI_ES builds an arp request in the buffer
;; pointed to by DI:ES  for the ip address that ends in AX

ARP_BUILD_REQUEST_in_AX_BX_DI_ES_const_AX_BX_DX_BP_ES MACRO name
    .errb <name>

    mov CX, AX      ;; save AX
    mov AX, SWAPPED_ARP_ETHER_TYPE
    stosw
    mov AX, SWAPPED_IP_TYPE
    stosw
    mov AX, 0406h   ;; byte swapped hardware address len, ip address len
    stosw
    mov AX, SWAPPED_ARP_REQUEST
    stosw
    mov SI, offset dl_ip_&name&_haddr   ;; copy me as source hardware address
    movsw
    movsw
    movsw
    mov SI, OFFSET dl_ip_&name&_ip    ;; and protocol address
    movsw
    movsw
    mov AX, 0
    stosw                             ;; target harware address
    stosw
    stosw
    mov AX, CX
    stosw                ;; target ip address
    xchg AX, BX
    stosw
    xchg AX, BX
ENDM


;;******************************************************************************
;; ARP_BUILD_REPLY_in_SI_ES converts the ARP request in SI:ES to a reply
;;   that has indicates that this node is the target of the request.  Note
;;   that this routine just copies the target IP address from the request,
;;   so that proxy arp is easy.

ARP_BUILD_REPLY_in_SI_ES_const_DX_BP_SI_ES MACRO name
    .errb <name>

    mov CX, SI                                  ;; save the pointer

    mov word ptr ES:[SI+arp_op], SWAPPED_ARP_REPLY
    mov AX, word ptr ES:[SI+arp_tpa]
    mov BX, word ptr ES:[SI+arp_tpa+2]
    add SI, offset arp_sha
    mov DI, CX
    add DI, offset arp_tha
    seges                       ;; copy source hardware and proto addr
    movsw
    seges
    movsw
    seges
    movsw
    seges
    movsw
    seges
    movsw

    mov DI, CX
    add DI, offset arp_sha
    mov SI, offset dl_ip_&name&_haddr
    movsw                       ;; put in me as source hardware addr
    movsw
    movsw

    stosw                       ;; put in TPA as source hardware addr
    mov AX, BX
    stosw
    mov SI, CX                  ;; restore SI
ENDM