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Assembly Source File | 1993-10-09 | 28.3 KB | 1,181 lines

; arp.asm ;======================================================================== ; Copyright (C) 1991 by Jan.Engvald@ldc.lu.se, see file COPYING. ;************************************************************************ ;************************************************************************ ;* ;* UDP/IP library ;* ;* This library is in a transition phase from a PDCLKSET specific library ;* into a multiprocess, reentrant, any hardware type, general UDP/IP ;* library. The buffers used have a descriptor part and a packet part. ;* The descriptor part is used to allow reentrancy, different physical ;* address lengths and varying number of IP options. ;* ;* In this library DS:BX always points to the descriptor buffer, DS:DI and ;* DS:SI usually points to the physical header/IP header/UDP header part of ;* the IP packet buffer and DX,AX often contains an IP number in network ;* byte order (DL,DH,AL,AH). For efficiency reasons, IP numbers are ;* searched last half first (first halves are often equal). ;* ;* As this library is still evolving, you can not assume that it looks ;* the same in the next release. In particular, if you are using any of ;* of the subroutines, check if their calls or results have been changed. ;* For the 2.0 version subroutine register usage has changed from save ;* almost everything to save almost nothing. This because it speeds up ;* execution speed significantly and there were only a few places where ;* it affected the caller so he had to save additional registers. ;* ;* The current implementation is RFC791 (IP) and RFC1122 (host requirements) ;* compliant, except for a few cases: I havn't found a reasonable solution ;* on how to report back to the application ICMP errors like parameter ;* problem, protocol and port unreachables, and fragment reassembly time ;* exceeded. Also, IP options are allowed, but the interpretation and handling ;* must be done by the application. Apart from the above, it is a de luxe ;* implementation that includes things like multiple default gateways, ;* sending protocol and port unreachables, IP type of service handling (not ;* tested), fragment reassembly and source quench introduced delay. ;* ;************************************************************************ ;************************************************************************ Descriptor struc dLink LinkStruc <> ; next & prev links ; dIOCB iocb <> ; pkt drvr hi perf struc dPtrPhys dw 0 ; ptr to physical hdr dPtrIp dw 0 ; ptr to IP hdr dPtrUdp dw 0 ; ptr to UDP hdr dPktLen dw 0 ; packet length (bytes) dPktEnd dw 0 ; end of packet dTimOut2Msg equ dPktEnd ; Timeout msg for findsends dSqDelay dw 0 ; source quench delay (ms) dWaitEvent dw 0 ; event to wait for dPtrFrag equ dWaitEvent ; ptr to defargment listhead dTimOutMsg dw 0 ; to be displayed at timeout dTickResend dw 1*18 ; resend start interval (ticks) dTickTimeout dw 4*18 ; timeout ticks (in 1/18 s) dTick2Timeout dw 14*18 ; second timeout dIdxHwDst equ dSqDelay ; arp table index for hw dst dIdxIpDst equ dTick2Timeout ; arp table index for IP dst dAdjust equ (4-(($-dLink) and 3)) and 3 if dAdjust db dAdjust dup (0) endif dGwys2Chk db 0 ; # of untried gateways dSnap db 0 ; 802.3 snaps used dPtrDes dw 0 ; ptr to start of descriptor dHwDst equ $-dLink ; (part of pd packet) Descriptor ends DESCRLEN equ SIZE Descriptor HwStruc struc hEthDst db 6 dup (0) ; Ethernet destination address hEthSrc db 6 dup (0) ; my Ether addr hProtType dw 0008 ; 0800 = IP HwStruc ends HWHDRLEN equ SIZE HwStruc SnapStruc struc sDSAP db 170 sSSAP db 170 sContr db 3 sOrgCode db 0,0,0 sProt db 08, 00 SnapStruc ends SNAPLEN equ SIZE SnapStruc ArpStruc struc iArpHtype dw 0 ; 0001 = Ether iArpProt dw 0008h ; 0800 = IP iArpHlen db 0 ; Hw addr length iArpPlen db 4 ; IP addr length iArpOp dw 0100h ; 0001 = request iArpMyHwAd db 2*MAX_ADDR_LEN+2*4 dup (0) ArpBodyLen = $-iArpHtype ArpStruc ends DriverClass label byte Class2Htype db 0 db 1 ; 1 Ethernet db 4 ; 2 Pronet-10 db 6 ; 3 802.5 TR db 0 ; 4 Omninet db 11 ; 5 LocalTalk db 0 ; 6 Slip if 0 db 1 ; 7 StarLan db 7 ; 8 Arcnet db 3 ; 9 AX.25 endif ifndef ARPSLOTS ARPSLOTS equ 12 endif ; The arp table contains information on hosts on this net. ; Slot 0, 1 and 2 (index 0, 2 and 4) are static and contain: ; this net broadcast, this subnet broadcast and my address, respectively. ; ; If we don't RECEIVE packets for more than a minute from a host or gateway, ; its slot is cleared. If we then DO receive a packet, the slot is restored ; by VerifyIpHdr without sending an ARP. On the other hand, if WE want to ; send the next packet, we will do an ARP and can thus detect dead hosts ; or gateways. even ArpTabIp2 dw 2 dup (0ffffh) ; IP # (last part) dw ARPSLOTS-2 dup (0) ArpTabIp1 dw 2 dup (0ffffh) ; IP # (first part) dw ARPSLOTS-2 dup (0) ArpTabTr dw ARPSLOTS dup (0) ; timer ArpTabFlags dw ARPSLOTS dup (0) ; flags ArpTabTrSq dw ARPSLOTS dup (0) ; source quench timer ArpTabSqDelay dw ARPSLOTS dup (0) ; source quench delay ArpTabHwAdr db ARPSLOTS*MAX_ADDR_LEN dup (0ffh) ; hardware addr (max 16 bytes) ArpTabHwEnd equ $ USE_SNAP equ 1 ; bit in ArpTabFlags SQ_UPDATED equ 2 ; bit in ArptabFlags/RouteTabFl ARPMYIDX equ 4 ArpPutSlot dw ARPMYIDX ArpType dw 0608h ArpBuf ArpStruc <> ArpFixedLen equ $-ArpType aArpOffsSrcIp equ iArpMyHwAd+2-iArpHtype MyHwAd equ ArpBuf.iArpMyHwAd IpType equ ArpBuf.iArpProt ArpFixedPart equ ArpType even DONT_WAIT equ 1 GOT_BOOTP equ 2 GOT_ARPREPLY equ 4 GOT_TIMEREPLY equ 8 GOT_ARPREQ equ 16 GOT_ICMPMSG equ 32 GOT_NSREPLY equ 64 Events dw 1 ; =1 so DONT_WAIT always true ARGZONE equ 2 ARGZONESPEC equ 4 DSTNOW equ 8 IS_A_386 equ 16 TBL_READY equ 32 UDP_ECHO equ 64 DBGSTOP equ 0080h ECHO_DISPL equ 0100h GOT_DSP_ROW equ 0200h CONT_ON_ERR equ 0400h ; = xor STOP_ON_ERR NO_ERR_YET equ 0800h NO_DROP_YET equ 1000h PING_DELAY equ 2000h PROBE_REPLY equ 4000h DBGINTERR equ 8000h GenFlags dw NO_DROP_YET SnapHdr SnapStruc <> ArpHandle dw 0 MySegm dw 0 Hlen dw 0 H2Len dw 0 LongerTimOut dw 0 SavedTicks dw 0 InSendAndW db 0 if DEBUG DbgIntCnt db 1 endif ; DEBUG ;************************************************************************ ;* CurrentTicks ;* Output: CX = low word of ticks (1/18 second) counter ;* Destroys: CX, ES ;************************************************************************ CurrentTicks proc near assume ds:nothing mov cx,040h ; DOS data segment mov es,cx mov cx,es:[6ch] ; get low word of ticks cntr mov cs:SavedTicks,cx ret CurrentTicks endp if RFCC ;************************************************************************ ;* HardwareTicks (48 bit time to si:dx:ax in 838 ns units) ;************************************************************************ TimerResolution equ 1193 ; hw ticks per millisecond InitTimer proc near assume ds:code_s test ArgFlags,AVOID_HDWR jnz InitTimRet mov dx,043h ; select timer control port mov al,034h out dx,al ; mode 2: Rate generator call IoDelay ; (counts down by 1 to zero) xor ax,ax mov dx,040h ; select timer 0 out dx,al ; set divide by 2**16 call IoDelay out dx,al ; the generator is now started InitTimRet: ret InitTimer endp RestoreTimer proc near assume ds:code_s test ArgFlags,AVOID_HDWR jnz ResTimRet mov dx,043h ; select timer control port mov al,036h out dx,al ; mode 3: Square wave generator call IoDelay ; (counts down by 2 to zero, xor ax,ax ; twice) mov dx,040h ; select timer 0 out dx,al ; set divide by 2**16 call IoDelay out dx,al ResTimRet: ret RestoreTimer endp IoDelay proc near assume ds:nothing push ax in al,061h ; ISA/EISA: 1us, MCA: 0.5 us pop ax ret IoDelay endp HardwareTicks proc near assume ds:nothing test cs:ArgFlags,AVOID_HDWR jnz HwTicksNoHi push es mov dx,020h ;/* Address PIC ocw3 */ mov al,00Ah ;/* Ask to read irr */ cli out dx,al xor al,al ;/* Latch timer 0 */ out 043h,al in al,040h ;/* Counter --> ax*/ mov ah,al ;/* LSB in AH */ in al,040h ;/* MSB in AL */ xchg al,ah not ax ;/* Need ascending counter */ push ax ; Save hardware counter value in al,dx ;/* Read irr */ push ax ; Save irr in al,021h ;/* Read PIC imr */ push ax ; Save imr mov al,00FFh ;/* Mask all interrupts */ out 021h,al mov ax,040h ;/* read low word of time */ mov es,ax ;/* from BIOS data area */ mov dx,es:[06Ch] mov si,es:[06Ch+2] ; get high word too pop ax ; Restore imr out 021h,al pop ax ; Restore irr test al,001h ;/* Counter hit 0? */ pop ax ; Restore counter value jnz HwTicksMore ;/* Jump if yes */ sti pop es ret HwTicksMore: cmp ax,0FFh ;/* Counter > 0x0FF? */ ja HwTicksDone ;/* Done if so */ add dx,1 ;/* Else count int req. */ adc si,0 HwTicksDone: sti pop es ret HwTicksNoHi: push es mov ax,040h mov es,ax cli mov dx,es:[06Ch] mov si,es:[06Ch+2] xor ax,ax sti pop es ret HardwareTicks endp endif ; RFCC ;************************************************************************ ;* OpenProt ;************************************************************************ OpenProt proc near assume ds:code_s push si ; save protocol ptr push ds mov ax,1ffh ; driver_info int_pkt pop ds call fatal_error mov ah,2 ; access all packets. mov al,ch ; their class from driver_info(). mov DriverClass,ch mov bx,offset Class2Htype ; class dependent code xlat mov byte ptr ArpBuf.iArpHtype+1,al cmp al,6 ; 802.2 ? jne InitNotSnap or GenFlags,USE_SNAP InitNotSNap: mov al,ch mov bx,dx ; their type from driver_info(). mov dl,cl ;their number from driver_info(). mov cx,2 ;type length of two. pop si ;ds:si -> protocol type push cs pop es mov di,offset Receiver ;es:di -> our receiver. push ds int_pkt pop ds call fatal_error ret OpenProt endp ;************************************************************************ ;* InitProtocols ;************************************************************************ InitProtocols proc near assume ds:code_s push sp ; find CPU features pop ax cmp ax,sp ; 286 or better? jne IsNot386 pushf pop ax or ax,7000h ;the 386 lets us set these bits push ax popf pushf pop ax test ax,7000h ;did the bits get set? jz IsNot386 ;no. or GenFlags,IS_A_386 ;yes, use a 386-optimized code IsNot386: call CurrentTicks ; get current ticks value mov BootpXid,cx if RFCC mov AgeNext,cx ; initialize ageing mov AgeFragsNext,cx endif ; RFCC mov si,offset IpType ; start IP call OpenProt mov IpHandle,ax cmp byte ptr ArpBuf.iArpHtype+1,0 ; need ARP? je InitArpNotUsed mov si,offset ArpType ; start ARP call OpenProt mov ArpHandle,ax mov bx,ax push cs pop es mov di,offset MyHwAd push di mov cx,15 mov ah,6 ; get my Hw addr push ds int_pkt pop ds call fatal_error mov ArpBuf.iArpHlen,cl ; save Hw address length mov Hlen,cx shl cx,1 mov H2Len,cx pop si ; my HW addr to ARP tab xor ax,ax mov dx,ax call ArpPutNew InitArpNotUsed: push cs pop es ret InitProtocols endp ;************************************************************************ ;* EndProtocol ;************************************************************************ EndProtocol proc near assume ds:code_s mov ah,3 ; release handle in bx push ds int_pkt pop ds call print_error ret EndProtocol endp ;************************************************************************ ;* MakeSendDescr ;* ;* Input: DS:BX = IP description buffer ptr (saved) ;* Output: Descriptor defaults filled in ;* DI = Udp ptr ;* Destroys: DI, flags ;************************************************************************ MakeSendDescr proc near assume ds:nothing push si push cx mov [bx].dSqDelay,0 mov [bx].dWaitEvent,0 mov [bx].dTimOutMsg,offset MsgNoConect mov [bx].dTickTimeout,4*18 mov [bx].dTickResend,1*18 lea di,[bx+DESCRLEN+2*MAX_ADDR_LEN+2+SNAPLEN] mov si,di sub si,2 xor cx,cx test cs:GenFlags,USE_SNAP ; 802.5 network? jz MakeNotSnap sub si,SNAPLEN inc cx MakeNotSnap: mov [bx].dSnap,cl sub si,cs:H2Len mov [bx].dPtrPhys,si add si,cs:MyGiant mov [bx].dPktEnd,si mov [bx].dPtrIp,di mov word ptr [di].iIpVerHlen,0045h ; IP ver 4; Tos = 0 mov [di].iIpFlFrag,0 mov [di].iIpTtl,90 add di,IPHDRLEN mov [bx].dPtrUdp,di pop cx pop si ret MakeSendDescr endp ;************************************************************************ ;* PutPhysSrc ;* ;* Input: DS:BX = IP description buffer ptr (saved) ;* ES = DS ;* Output: HW src addr and IP prot type put into pkt ;* CX = phys header length ;* Destroys: CX, SI, DI, ES, flags, enables interrupt ;************************************************************************ PutPhysSrc proc near assume ds:nothing CHK_ES_EQ_DS mov si,offset MyHwAd ; get my HW addr from ARP buf mov di,[bx].dPtrPhys mov cx,cs:Hlen add di,cx PutPhysLoop1: cli rep movs byte ptr es:[hEthSrc],cs:[MyHwAd] sti test [bx].dSnap,1 ; use snap? jz PutPhysNotSnap mov cx,[bx].dPktLen add cx,SNAPLEN xchg ch,cl mov [di],cx add di,2 mov si,offset SnapHdr rept (sProt-sDSAP)/2 movs word ptr es:[sDSAP], word ptr cs:[SnapHdr] endm PutPhysNotSnap: mov cx,di sub cx,[bx].dPtrPhys add cx,2 ; physical header length mov word ptr [di],0008h ; protocol type IP (0800) ret PutPhysSrc endp ;************************************************************************ ;* ArpFindIp ;* ;* Input: DX = first word of IP # (saved) ;* AX = second word of IP # (saved) ;* A PushfDI must be done before calling ;* Output: if found: zero and DI = arp table index ;* ES = CS ;* Destroys: CX, DI, ES, flags ;************************************************************************ ArpFindIp proc near assume ds:nothing mov es,cs:MySegm mov di,offset ArpTabIp2 mov cx,ARPSLOTS ArpFindIpNext: ; look for matching slot repne scasw jnz ArpFindIpRet cmp dx,cs:2*ARPSLOTS-2[di] ; does IP # first part match? jne ArpFindIpNext ; - no, look further sub di,offset ArpTabIp2+2 ; - yes, compute slot index cmp di,di ; set zero flag ArpFindIpRet: ret ArpFindIp endp ;************************************************************************ ;* ArpFindHw ;* ;* Input: DS:AX = address of HW addr ;* A PushfDI must be done before calling ;* Output: if found: zero and DI = arp table index ;* ES = CS ;* Destroys: (AX,) DX, CX, SI, DI, ES, flags ;************************************************************************ ArpFindHwHl proc near assume ds:nothing add ax,cs:Hlen ; get physical src addr ArpFindHw: mov es,cs:MySegm mov dx,offset ArpTabHwAdr+MAX_ADDR_LEN ; first two entries are similar ArpFindHwNext: mov cx,cs:Hlen mov di,dx mov si,ax repe cmpsb ; is this hw addr in arp tab? jz ArpFindHwFound add dx,MAX_ADDR_LEN ; check next entry cmp dx,offset ArpTabHwEnd-MAX_ADDR_LEN ; more entries? jbe ArpFindHwNext ret ; not found (non-zero) return ArpFindHwFound: sub dx,offset ArpTabHwAdr shr dx,1 shr dx,1 shr dx,1 mov di,dx cmp di,di ret ; found (zero) return ArpFindHwHl endp ;************************************************************************ ;* ArpPutHwAd ;* ;* Input: DS:SI = pointer to physical address (saved) ;* DS:BX = descriptor buffer ptr (saved) ;* DI = arp table index ;* A PushfDI must be done before calling ;* Destroys: CX, DI, ES, flags ;************************************************************************ ArpPutHwAd proc near assume ds:nothing mov es,cs:MySegm push si mov cx,cs:SavedTicks ; get current ticks value mov cs:ArpTabTr[di],cx mov cx,cs:ArpTabFlags[di] and cl,not USE_SNAP or cl,[bx].dSnap ; remember if snaps used mov cs:ArpTabFlags[di],cx ; by that host mov cl,3 ; put hw addr into slot shl di,cl lea di,ArpTabHwAdr[di] mov cx,cs:Hlen rep movsb pop si ret ArpPutHwAd endp ;************************************************************************ ;* ArpPutHwDst ;* ;* Input: DX = first word of IP # (saved) ;* AX = second word of IP # (saved) ;* DS:BX = description buffer ptr (saved) ;* Output: if found: zero, HW dst addr copied to pkt and CX = 0 ;* ES = DS ;* Destroys: CX, SI, DI, ES, flags ;************************************************************************ ArpPutHwDst proc near assume ds:nothing cli call ArpFindIp ; IP # in arp table? mov cx,ds mov es,cx jnz ArpPutHwRet ; - no, non-zero (not found) mov cx,cs:ArpTabFlags[di] ; use snap if neeeded and cl,USE_SNAP mov [bx].dSnap,cl ; by dst host if RFCC push ax mov cx,cs:SavedTicks mov ax,cs:ArpTabSqDelay[di] ; move sq delay to descriptor mov [bx].dSqDelay,ax dec ax ; any delay? js ArpNoSqDelay mov ax,cs:ArpTabTrSq[di] ; - yes add ax,18 ; has one second has passed cmp ax,cx ; since we last decremented jns ArpNoSqDelay ; the delay value? mov cs:ArpTabTrSq[di],cx dec cs:ArpTabSqDelay[di] ; - yes, one millisecond off ArpNoSqDelay: pop ax endif ; RFCC mov cl,3 ; - yes, copy HW addr shl di,cl lea si,ArpTabHwAdr[di] mov di,[bx].dPtrPhys mov cx,cs:Hlen rep movs byte ptr es:[hEthDst],cs:[ArpTabHwAdr] cmp di,di ; zero (found) return ArpPutHwRet: sti ret ArpPutHwDst endp ;************************************************************************ ;* ArpPutNew ;* ;* Input: DX = first word of IP # (saved) ;* AX = second word of IP # (saved) ;* SI = pointer to physical address (saved) ;* Destroys: CX, DI, ES, flags ;************************************************************************ ArpPutNewSiHl proc near assume ds:nothing mov si,[bx].dPtrPhys add si,cs:Hlen ArpPutNew: PushfDI call ArpFindIp ; already have IP # ? jz ArpPutHere ; - yes, update hw addr ArpPutWrap: ; - no, find next slot mov di,cs:ArpPutSlot add di,2 ; advance index two bytes cmp di,2*ARPSLOTS ; end of arp table? jb ArpPut mov di,ARPMYIDX+2 ; preserve bcast mappings ArpPut: ; (first slots) if TBLBUILD push si mov si,di add si,2 cmp si,2*ARPSLOTS jb ArpPut2 mov si,ARPMYIDX+2 ArpPut2: mov cx,cs:ArpTabTr[di] sub cx,cs:ArpTabTr[si] js ArpPut3 mov di,si ; use elder of next 2 slots ArpPut3: pop si endif ; TBLBUILD mov cs:ArpPutSlot,di mov cs:ArpTabIp1[di],dx ; put IP # into slot mov cs:ArpTabIp2[di],ax xor cx,cx ; clear other fileds mov cs:ArpTabFlags[di],cx mov cs:ArpTabSqDelay[di],cx ArpPutHere: call ArpPutHwAd ; put HW addr into slot PopfEI ret ArpPutNewSiHl endp ;************************************************************************ ;* SendAndWait ;* Input: DS:BX = description buffer ptr (saved) ;* Output: Zero and CX = 0 if OK ;* non-zero and CX = errorcode if error ;* Destroys: AX, CX, DX, SI, DI, ES, flags ;************************************************************************ SendAndWait proc near assume ds:nothing inc cs:InSendAndW mov si,[bx].dWaitEvent ; event to wait for or si,si ; no event to wait for? jz SendDontWait not si and cs:Events,si ; clear this event bit SendDontWait: not si push si if RFCC ; Do RFC1016 Source Quench Introduced Delay mov di,[bx].dSqDelay or di,di ; any SQ delay? jz SendNoSqDelay call HardwareTicks call DblShr10 add di,ax test cs:ArgFlags,AVOID_HDWR jz SendSqLoop add di,55/2 ; round up SendSqLoop: call Something2Do ; wait a while call HardwareTicks call DblShr10 cmp ax,di ; can we send it now? js SendSqLoop SendNoSqDelay: endif ; RFCC call SendRawPkt ; send packet part of buffer pop si test cs:Events,si ; got what we want? jz SendWait4Rep SendWaitOK: xor cx,cx SendWaitRet: dec cs:InSendAndW or cx,cx ret SendWait4Rep: mov cx,cs:SavedTicks mov di,[bx].dTickResend ; first resend time mov ax,cx add ax,di add ax,cs:LongerTimOut mov dx,cx add dx,cs:LongerTimOut add dx,[bx].dTickTimeout ; time out time WaitLoop: test cs:Events,si ; got what we want? jnz SendWaitOK SendChk: call Something2Do ; anything else to do? ChkTimeout: call CurrentTicks cmp cx,dx ; time out? jns SendTimedout cmp cx,ax ; time to resend? js WaitLoop shl di,1 ; double resend time cmp di,30*18 jbe SendDouble mov di,30*18 ; max 30 seconds SendDouble: add ax,di ; next resend time push ax push dx push si push di call SendRawPkt ; send same packet again pop di pop si pop dx pop ax jmp short WaitLoop SendTimedout: mov dx,[bx].dTimOutMsg mov cx,SERRTIMOUT or dx,dx ; if no timeout msg jz SendWaitRet ; just return mov al,04 ; error code 4 call PrTerminate ; print error msg in dx SendAndWait endp ;************************************************************************ ;* SendRawPkt ;* Input: DS:BX = description buffer ptr (saved) ;* Destroys: AX, CX, DX, SI, DI, ES, flags ;************************************************************************ SendRawPkt proc near assume ds:nothing if PINGCLIENT mov ax,[bx].dPktLen add ax,8+4+12 ; preamble, crc, intergap cli add cs:EchoLoad+2,ax adc cs:EchoLoad,0 sti endif ; PINGCLIENT mov ax,3000 ; # of retries if temporary err SendRawAgain: push ax push bx push bp mov si,[bx].dPtrPhys ; get start of packet mov cx,[bx].dPktLen ; and its length mov ah,4 ; send packet to push ds ; packet driver int_pkt pop ds pop bp pop bx pop ax jc SendBadPkt ; any errors? if DEBUG mov ax,0aaaah ; trash regs mov cx,ax mov dx,ax mov si,ax mov es,ax endif ; DEBUG ret SendBadPkt: cmp dh,CANT_SEND ; can't send? jne SendPermBad SendTempBad: dec ax ; have we tried enough times? jnz SendRawAgain SendPermBad: stc call print_error ; display explanation mov al,03 ; error code 3 call Terminate SendRawPkt endp ;************************************************************************ ;* SendArpReq ;* ;* Input: DX = first word of IP # (saved) ;* AX = second word of IP # (saved) ;* DS:BX = IP description buffer ptr (saved) ;* Output: Zero and CX = 0 if OK ;* non-zero and CX = errorcode if error ;* Destroys: CX, SI, DI, ES, flags ;************************************************************************ SendArpReq proc near assume ds:nothing push dx ; dx,ax has IP # to arp for push ax push bx ; save IP descr addr push ds call BufAlloc ; get a buffer mov cx,SERRNOBUF jz SendArpRet call MakeSendDescr ; set up descriptor mov di,[bx].dPtrPhys mov si,offset ArpTabHwAdr ; put Ether broadcast dst mov cx,cs:Hlen SendArpL1: movs byte ptr es:[hEthDst],cs:[ArpTabHwAdr] loop SendArpL1 call PutPhysSrc ; put Ether src addr push di mov si,offset ArpFixedPart ; copy in static arp part mov cx,ArpFixedLen-2*MAX_ADDR_LEN add cx,cs:H2len SendArpL2: movs byte ptr es:[hEthSrc],byte ptr cs:[ArpFixedPart] loop SendArpL2 sub di,[bx].dPtrPhys ; calculate packet length mov [bx].dPktLen,di pop di ; compute addr to dst IP # add di,aArpOffsSrcIp add di,cs:H2Len mov [di+4],dx ; IP # to arp for mov [di+4+2],ax sub di,cs:Hlen ; fill in My IP # mov dx,cs:MyIpNr mov ax,cs:MyIpNr+2 mov [di],dx mov [di+2],ax pop es pop si ; IP descr addr push si push es mov cx,es:[si].dTimOutMsg ; use application timeout msg mov [bx].dTimOutMsg,cx mov cx,es:[si].dTickTimeout cmp cx,3*18 ; limit arp timeout jbe SendArpOkTim mov cx,3*18 ; to 3 seconds or less SendArpOkTim: mov [bx].dTickTimeout,cx mov [bx].dWaitEvent,GOT_ARPREPLY call SendAndWait ; send arp request packet call BufRelease ; release buffer SendArpRet: or cx,cx pop ds ; restore IP descr addr pop bx pop ax ; restore IP # we ARPed for pop dx ret SendArpReq endp ;************************************************************************ ;* ARP receiver (branched off from general receiver) * ;************************************************************************ assume ds:nothing ArpRecvCont: SHOW_EVENT 'C' push di mov ax,[bx].dPtrPhys call ArpFindHwHl ; Hw Src addr in ARP table? pop si jnz ArpRecNew cmp di,ARPMYIDX ; ignore pkts from bcast or me jbe ArpRecRet ; (also helps NDIS) ArpRecNew: lea di,[si].iArpMyHwAd mov cx,[si].iArpOp ; ARP reply? mov si,di add di,cs:Hlen mov dx,word ptr [di] ; get HIS (!) IP # and keep mov ax,word ptr [di+2] ; it for a long while add di,4 cmp di,[bx].dPktEnd ; big enough to be arp pkt? ja ArpRecRet ; The following test is not according to the ARP RFC. The reason for this ; divergence is that if we follow the RFC algorithm, anybody that momentarily ; uses a wrong IP number would disrupt our communication with the original ; owner of that IP number. This would be true even if the program he uses ; is nice (NCSA Telnet for example) and starts by sending an ARP packet for ; itself to see if anybody will answer (a very good thing to do and this ; package does so too). ; ; We do obey an unsolicited arp reply immediately, other cases of changed ; hardware address will be taken care of in a minute automagically by the ; arp table ageing mechanism, so this package should do well even when moving ; hosts in a proxy arp environment. cmp cx,0200h ; ARP reply? jne ArpNotReply call ArpFindIp ; if he is in our ARP table we jnz ArpNotThere SHOW_EVENT 'D' call ArpPutHwAd ; should update his HW addr ArpNotThere: ArpNotReply: mov di,si add di,cs:H2Len mov cx,[di+4] cmp cx,cs:MyIpNr ; is this arp for me? jne ArpRecTbl mov cx,[di+6] cmp cx,cs:MyIpNr+2 jne ArpRecTbl add di,8 cmp di,[bx].dPktEnd ja ArpRecRet SHOW_EVENT 'E' call ArpPutNew ; - yes, put his IP # and HW ; addr into the ARP table mov di,[bx].dPtrIp cmp [di].iArpOp,0100h ; arp request? je ArpRecReq or cs:Events,GOT_ARPREPLY ; - no, probably a wanted reply ArpRecTbl: if TBLBUILD test cs:ArgFlags,MAKE_TABLE jnz ArpRecBld endif ; TBLBUILD ArpRecRet: jmp IpRecRet ArpRecKeepBuf: jmp IpRecKeepBuf if TBLBUILD ArpRecBld: cmp cs:FreeBufs.lBufsAvail,NBUFS/4 ; prevent starving jbe ArpRecRet test cs:GenFlags,TBL_READY jz ArpRecRet SHOW_EVENT 'F' mov si,offset TblToDo call AddToList ; collect adress info jmp short ArpRecKeepBuf endif ; TBLBUILD ArpRecReq: SHOW_EVENT 'G' mov [di].iArpOp,0200h ; put arp reply code mov di,si push di push ds pop es mov cx,cs:Hlen add cx,4 add di,cx rep movsb ; mov arp dst to arp src pop di mov si,offset MyHwAd mov cx,cs:Hlen ArpRecReqL1: movs byte ptr es:[hEthSrc],cs:[MyHwAd] ; put in my HW addr as arp src loop ArpRecReqL1 mov cx,cs:MyIpNr mov [di],cx ; put my IP # to arp src mov si,cs:MyIpNr+2 mov [di+2],si cmp dx,cx ; is he stealing my IP # ? jne ArpRecNoSteal cmp ax,si jne ArpRecNoSteal mov dx,0ffffh ; - yes, tell everybody by mov ax,dx ; broadcasting my reply ArpRecNoSteal: mov [bx].dWaitEvent,0 call ArpPutHwDst ; put dst Ether addr fr DX,AX call PutPhysSrc ; put src Ether addr mov word ptr [di],0608h ; arp prot mov si,offset SendToDo ; put buffer on the send list call AddToList ; for non-interrupt handling jmp short ArpRecKeepBuf ;======================================================================== ; endinclude