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ICMP.INC
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1992-06-09
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;;*************************************************************************
; icmp.inc icmp.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.
;;
;;*****************************************************************************
;;
;; Routines provided by this package
;;
;; ICMP_DECLARE name, net, router
;; ICMP_DEFINE name
;; ICMP_ERROR_in_SI_ES name, type, code, ip
;; ICMP_REDIRECT_in_AX_BX_SI_ES name, code, ip
;;
;; AUTHOR: Vance Morrison
;; DATE: 5/9/89
;;*****************************************************************************
ICMP_PROTO = 1
;; values for the type field
ICMP_ECHO_REPLY = 0
ICMP_ECHO_REQUEST = 8
ICMP_TIME = 11
ICMP_UNREACHABLE = 3
ICMP_REDIRECT = 5
;; values for the code field
ICMP_TIME_TTL = 0
ICMP_UNREACH_NET = 0
ICMP_UNREACH_HOST = 1
ICMP_UNREACH_PROTO = 2
ICMP_UNREACH_PORT = 3
ICMP_REDIRECT_NET = 0
ICMP_REDIRECT_HOST = 1
ICMP_REDIRECT_TOS_NET = 2
ICMP_REDIRECT_TOS_HOST = 3
icmp STRUC ;; icmp packets
icmp_type DB ?
icmp_code DB ?
icmp_check DW ?
icmp_id DW ?
icmp_seq DW ?
icmp ENDS
icmp_data STRUC
icmp_read_off DW ?
icmp_read_seg DW ?
icmp_read_len DW ?
icmp_error_off DW ?
icmp_error_seg DW ?
icmp_gateway DD ?
icmp_data ENDS
;;*****************************************************************************
;; ICMP_DECLARE name, net, router
;;
ICMP_DECLARE MACRO name, net, router
.errb <router>
.DATA
icmp_&name&_net = net
icmp_&name&_router = router
global icmp_&name&_data:icmp_data
.CODE
ENDM
;;*****************************************************************************
;; ICMP_DEFINE name
;; 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).
;;
ICMP_DEFINE MACRO name
local icmp_packet, around
.errb <name>
.DATA
icmp_&name&_data icmp_data <>
.CODE
jmp around ;; set up the listener
icmp_packet:
ICMP_PACKET_in_BX_ES name
RET
around:
IP_R_READ %icmp_&name&_net, ICMP_PROTO, icmp_packet
ENDM
;;*****************************************************************************
;; ICMP_REDIRECT_in_AX_BX_SI_ES name, code
;; ICMP_REDIRECT sends a redirect with the ICMP code of 'code' to the host
;; sending the IP packet SI:ES instructing this host to redirect packets
;; to the gateway AX,BX
;;
ICMP_REDIRECT_in_AX_BX_SI_ES MACRO name, code, ip
local done
.errb <ip>
ICMP_DO_REPLY_in_AX_BX_SI_ES name, ICMP_REDIRECT, code, ip
ENDM
;;*****************************************************************************
;; ICMP_ERROR_in_SI_ES returns an error code of type 'type' and code 'code'
;; to the sender of the IP packet pointed to by SI:ES
;;
ICMP_ERROR_in_SI_ES MACRO name, type, code, ip
local done
.errb <ip>
xor AX, AX
xor BX, BX
ICMP_DO_REPLY_in_AX_BX_SI_ES name, type, code, ip
ENDM
;;*****************************************************************************
;; ICMP_DO_REPLY returns an error code of type 'type' and code 'code'
;; to the sender of the IP packet pointed to by SI:ES with the gatway part
;; of the header set to AX,BX
;;
ICMP_DO_REPLY_in_AX_BX_SI_ES MACRO name, type, code, ip
local done
.errb <ip>
cmp byte ptr ES:[SI+ip_proto], ICMP_PROTO ;; no errors about ICMP
jz done
mov word ptr icmp_&name&_data.icmp_gateway, AX
mov word ptr icmp_&name&_data.icmp_gateway+2, BX
mov word ptr icmp_&name&_data.icmp_error_off, SI
mov word ptr icmp_&name&_data.icmp_error_seg, ES
mov AX, word ptr ES:[SI+ip_src]
mov BX, word ptr ES:[SI+ip_src+2]
mov DL, ICMP_PROTO
mov CX, 8+60+8
IP_W_ACCESS_in_AX_BX_CX_DL_out_AX_DI_ES ip
or AX, AX
jnz done ;; check return code
mov BP, DI ;; save DI
mov AL, type ;; fill in the header
mov AH, code
stosw
xor AX, AX
stosw ;; the checksum
mov AX, word ptr icmp_&name&_data.icmp_gateway
stosw
mov AX, word ptr icmp_&name&_data.icmp_gateway+2
stosw
mov BX, DS ;; save DS
lds SI, dword ptr icmp_&name&_data.icmp_error_off
mov CX, 28
mov DX, CX ;; save CX
rep ;; copy the packet
movsb
mov DS, BX ;; restore DS
add DX, 8
mov CX, DX ;; restore CX
mov SI, BP ;; restore packet pointer
ICMP_COMPUTE_CHECK_in_CX_SI_ES_out_BX_const_DX_BP_DI_ES
mov DI, BP
mov word ptr ES:[DI+icmp_check], BX
mov CX, DX
IP_W_WRITE_in_CX ip
done:
ENDM
;;*****************************************************************************
ICMP_COMPUTE_CHECK_in_CX_SI_ES_out_BX_const_DX_BP_DI_ES MACRO
local check_loop
xor BX, BX ;; also clears carry
shr CX, 1
check_loop:
seges
lodsw
adc BX, AX
loop check_loop
adc BX, 0 ;; add in the last carry if any
not BX
ENDM
;;*****************************************************************************
;; ICMP_PACKET processes the ICMP packet that starts at BX:ES (this is the
;; start if the IP part of the packet
;;
ICMP_PACKET_in_BX_ES MACRO name
local not_ping, done
.errb <name>
mov word ptr icmp_&name&_data.icmp_read_off, BX
mov word ptr icmp_&name&_data.icmp_read_seg, ES
mov word ptr icmp_&name&_data.icmp_read_len, CX
mov SI, BX
cmp byte ptr ES:[SI+icmp_type], ICMP_ECHO_REQUEST
jnz not_ping
IP_R_SRC_in_SI_ES_out_AX_BX_const_CX_DX_BP_SI_DI_ES %icmp_&name&_net
mov DL, ICMP_PROTO
IP_W_ACCESS_in_AX_BX_CX_DL_out_AX_DI_ES %icmp_&name&_net
or AX, AX
jnz done ;; check return code
mov DX, DS ;; save DS
mov CX, word ptr icmp_&name&_data.icmp_read_len
lds SI, dword ptr icmp_&name&_data.icmp_read_off
mov BX, CX ;; save CX
mov [SI+icmp_type], ICMP_ECHO_REPLY
mov AX, [SI+icmp_check] ;; fix up ICMP checksum
add AX, (ICMP_ECHO_REQUEST - ICMP_ECHO_REPLY)
adc AX, 0
mov [SI+icmp_check], AX
rep ;; copy the ping
movsb
mov DS, DX ;; restore DS
mov CX, BX ;; restore CX
IP_W_WRITE_in_CX %icmp_&name&_net
jmp done
not_ping:
done:
ENDM