WebSVN – Kolibri OS – Diff – /kernel/trunk/network/icmp.inc


$Revision: 431 $
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
;;                                                              ;;
;; Copyright (C) KolibriOS team 2004-2007. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License    ;;
;;                                                              ;;
;;  ICMP.INC                                                    ;;
 
;;                                                              ;;
;;  Internet Control Message Protocol ( RFC 792 )               ;;
 
;;                                                              ;;
;;  Last revision: 11.11.2006                                   ;;
 
;;                                                              ;;
;;  This file contains the following:                           ;;
;;   icmp_rx - processes ICMP-packets received by the IP layer  ;;
 
;;                                                              ;;
;;  Changes history:                                            ;;
;;   22.09.2003 - [Mike Hibbett] : mikeh@oceanfree.net          ;;
;;   11.11.2006 - [Johnny_B] and [smb]                          ;;
 
;;                                                              ;;
;;   Current status:                                            ;;
;;	This implemetation of ICMP proto supports message of ECHO type.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 
struc ICMP_PACKET
{  .Type            db   ?  ;+00
   .Code            db   ?  ;+01
   .Checksum        dw   ?  ;+02
   .Identifier      dw   ?  ;+04
   .SequenceNumber  dw   ?  ;+06
   .Data            db   ?  ;+08
}
 
virtual at 0
  ICMP_PACKET ICMP_PACKET
end virtual
 
 
;   Example:
;	ECHO message format
;
;
;           0               1               2               3
;    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
;   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;   |     Type      |     Code      |          Checksum             |
;   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;   |           Identifier          |        Sequence Number        |
;   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
;   |     Data ...
;   +-+-+-+-+-
;
 
;
; ICMP types & codes, RFC 792 and FreeBSD's ICMP sources
;
 
ICMP_ECHOREPLY		equ	0		; echo reply message
 
ICMP_UNREACH		equ	3
	ICMP_UNREACH_NET	equ	0		; bad net
	ICMP_UNREACH_HOST	equ	1		; bad host
	ICMP_UNREACH_PROTOCOL	equ	2		; bad protocol
	ICMP_UNREACH_PORT	equ	3		; bad port
	ICMP_UNREACH_NEEDFRAG	equ	4		; IP_DF caused drop
	ICMP_UNREACH_SRCFAIL	equ	5		; src route failed
	ICMP_UNREACH_NET_UNKNOWN equ	6		; unknown net
	ICMP_UNREACH_HOST_UNKNOWN equ	7		; unknown host
	ICMP_UNREACH_ISOLATED	equ	8		; src host isolated
	ICMP_UNREACH_NET_PROHIB	equ	9		; prohibited access
	ICMP_UNREACH_HOST_PROHIB equ	10		; ditto
	ICMP_UNREACH_TOSNET	equ	11		; bad tos for net
	ICMP_UNREACH_TOSHOST	equ	12		; bad tos for host
	ICMP_UNREACH_FILTER_PROHIB equ	13		; admin prohib
	ICMP_UNREACH_HOST_PRECEDENCE equ 14		; host prec vio.
	ICMP_UNREACH_PRECEDENCE_CUTOFF equ 15		; prec cutoff
 
ICMP_SOURCEQUENCH	equ	4		; packet lost, slow down
 
ICMP_REDIRECT		equ	5		; shorter route, codes:
	ICMP_REDIRECT_NET	equ	0		; for network
	ICMP_REDIRECT_HOST	equ	1		; for host
	ICMP_REDIRECT_TOSNET	equ	2		; for tos and net
	ICMP_REDIRECT_TOSHOST	equ	3		; for tos and host
 
ICMP_ALTHOSTADDR	equ	6		; alternate host address
ICMP_ECHO		equ	8		; echo service
ICMP_ROUTERADVERT	equ	9		; router advertisement
	ICMP_ROUTERADVERT_NORMAL equ 0			; normal advertisement
	ICMP_ROUTERADVERT_NOROUTE_COMMON equ 16		; selective routing
 
ICMP_ROUTERSOLICIT	equ	10		; router solicitation
ICMP_TIMXCEED		equ	11		; time exceeded, code:
    ICMP_TIMXCEED_INTRANS	equ	0		; ttl==0 in transit
    ICMP_TIMXCEED_REASS	equ	1		; ttl==0 in reass
 
ICMP_PARAMPROB            equ  12		; ip header bad
    ICMP_PARAMPROB_ERRATPTR   equ  0		; error at param ptr
    ICMP_PARAMPROB_OPTABSENT  equ  1		; req. opt. absent
    ICMP_PARAMPROB_LENGTH     equ  2		; bad length
 
ICMP_TSTAMP		equ	13		; timestamp request
ICMP_TSTAMPREPLY	equ	14		; timestamp reply
ICMP_IREQ		equ	15		; information request
ICMP_IREQREPLY		equ	16		; information reply
ICMP_MASKREQ		equ	17		; address mask request
ICMP_MASKREPLY		equ	18		; address mask reply
ICMP_TRACEROUTE		equ	30		; traceroute
ICMP_DATACONVERR	equ	31		; data conversion error
ICMP_MOBILE_REDIRECT	equ	32		; mobile host redirect
ICMP_IPV6_WHEREAREYOU	equ	33		; IPv6 where-are-you
 ICMP_IPV6_IAMHERE	equ	34		; IPv6 i-am-here
ICMP_MOBILE_REGREQUEST	equ	35		; mobile registration req
ICMP_MOBILE_REGREPLY	equ	36		; mobile registreation reply
ICMP_SKIP		equ	39		; SKIP
 
ICMP_PHOTURIS		equ	40		; Photuris
    ICMP_PHOTURIS_UNKNOWN_INDEX   equ  1		; unknown sec index
    ICMP_PHOTURIS_AUTH_FAILED     equ  2		; auth failed
    ICMP_PHOTURIS_DECRYPT_FAILED  equ  3		; decrypt failed
 
 
;***************************************************************************
;   Function
;      icmp_rx  [by Johnny_B]
;
;   Description
;       ICMP protocol handler
;       This is a kernel function, called by ip_rx
;
;  IN:
;    buffer_number  - # of IP-buffer. This buffer must be reused or marked as empty afterwards
;    IPPacketBase   - IP_PACKET base address
;    IPHeaderLength - Header length of IP_PACKET
;
;  OUT:
;    EAX=not defined
;
;           All used registers will be saved
;
;***************************************************************************
proc icmp_rx  stdcall  uses ebx esi edi,\
    buffer_number:DWORD,IPPacketBase:DWORD,IPHeaderLength:DWORD
 
    mov     esi,[IPPacketBase]   ;esi=IP_PACKET base address
    mov     edi, esi
    add     edi,[IPHeaderLength] ;edi=ICMP_PACKET base address
 
    cmp     byte[edi + ICMP_PACKET.Type], ICMP_ECHO ; Is this an echo request? discard if not
    jz      .icmp_echo
 
    mov     eax, [buffer_number]
    call    freeBuff
    jmp     .exit
 
  .icmp_echo:
 
    ; swap the source and destination addresses
    mov     ecx, [esi + IP_PACKET.DestinationAddress]
    mov     ebx, [esi + IP_PACKET.SourceAddress]
    mov     [esi + IP_PACKET.DestinationAddress], ebx
    mov     [esi + IP_PACKET.SourceAddress], ecx
 
    ; recalculate the IP header checksum
    mov     eax,[IPHeaderLength]
    stdcall checksum_jb,esi,eax   ;buf_ptr,buf_size
 
    mov     byte[esi + IP_PACKET.HeaderChecksum], ah
    mov     byte[esi + IP_PACKET.HeaderChecksum + 1], al      ; ?? correct byte order?
 
    mov     byte[edi + ICMP_PACKET.Type], ICMP_ECHOREPLY  ; change the request to a response
    mov     word[edi + ICMP_PACKET.Checksum], 0  ; clear ICMP checksum prior to re-calc
 
    ; Calculate the length of the ICMP data ( IP payload)
    xor     eax, eax
    mov     ah, byte[esi + IP_PACKET.TotalLength]
    mov     al, byte[esi + IP_PACKET.TotalLength + 1]
    sub     ax, word[IPHeaderLength]  ;ax=ICMP-packet length
 
    stdcall checksum_jb,edi,eax   ;buf_ptr,buf_size
 
    mov     byte[edi + ICMP_PACKET.Checksum], ah
    mov     byte[edi + ICMP_PACKET.Checksum + 1], al
 
    ; Queue packet for transmission
    mov     ebx, [buffer_number]
    mov     eax, NET1OUT_QUEUE
    call    queue
 
  .exit:
    ret
endp

Subversion Repositories Kolibri OS

(root)/kernel/trunk/network/icmp.inc – Rev 425 → 431

Rev 425		Rev 431
1	$Revision: 425 $	1	$Revision: 431 $
2	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;	2	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
3	;;	-
-		3	;; ;;
-		4	;; Copyright (C) KolibriOS team 2004-2007. All rights reserved. ;;
-		5	;; Distributed under terms of the GNU General Public License ;;
-		6	;; ;;
4	;; ICMP.INC	7	;; ICMP.INC ;;
5	;;	-
-		8	;; ;;
6	;; Internet Control Message Protocol ( RFC 792 )	9	;; Internet Control Message Protocol ( RFC 792 ) ;;
7	;;	-
-		10	;; ;;
8	;; Last revision: 11.11.2006	11	;; Last revision: 11.11.2006 ;;
9	;;	-
-		12	;; ;;
10	;; This file contains the following:	13	;; This file contains the following: ;;
11	;; icmp_rx - processes ICMP-packets received by the IP layer	14	;; icmp_rx - processes ICMP-packets received by the IP layer ;;
12	;;	-
-		15	;; ;;
13	;; Changes history:	16	;; Changes history: ;;
14	;; 22.09.2003 - [Mike Hibbett] : mikeh@oceanfree.net	17	;; 22.09.2003 - [Mike Hibbett] : mikeh@oceanfree.net ;;
15	;; 11.11.2006 - [Johnny_B] and [smb]	18	;; 11.11.2006 - [Johnny_B] and [smb] ;;
16	;;	-
-		19	;; ;;
17	;; Current status:	20	;; Current status: ;;
18	;; This implemetation of ICMP proto supports message of ECHO type.	21	;; This implemetation of ICMP proto supports message of ECHO type.
19	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;	22	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
20		23
21		24
22	struc ICMP_PACKET	25	struc ICMP_PACKET
23	{ .Type db ? ;+00	26	{ .Type db ? ;+00
24	.Code db ? ;+01	27	.Code db ? ;+01
25	.Checksum dw ? ;+02	28	.Checksum dw ? ;+02
26	.Identifier dw ? ;+04	29	.Identifier dw ? ;+04
27	.SequenceNumber dw ? ;+06	30	.SequenceNumber dw ? ;+06
28	.Data db ? ;+08	31	.Data db ? ;+08
29	}	32	}
30		33
31	virtual at 0	34	virtual at 0
32	ICMP_PACKET ICMP_PACKET	35	ICMP_PACKET ICMP_PACKET
33	end virtual	36	end virtual
34		37
35		38
36	; Example:	39	; Example:
37	; ECHO message format	40	; ECHO message format
38	;	41	;
39	;	42	;
40	; 0 1 2 3	43	; 0 1 2 3
41	; 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7	44	; 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
42	; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+	45	; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
43	; \| Type \| Code \| Checksum \|	46	; \| Type \| Code \| Checksum \|
44	; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+	47	; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
45	; \| Identifier \| Sequence Number \|	48	; \| Identifier \| Sequence Number \|
46	; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+	49	; +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
47	; \| Data ...	50	; \| Data ...
48	; +-+-+-+-+-	51	; +-+-+-+-+-
49	;	52	;
50		53
51	;	54	;
52	; ICMP types & codes, RFC 792 and FreeBSD's ICMP sources	55	; ICMP types & codes, RFC 792 and FreeBSD's ICMP sources
53	;	56	;
54		57
55	ICMP_ECHOREPLY equ 0 ; echo reply message	58	ICMP_ECHOREPLY equ 0 ; echo reply message
56		59
57	ICMP_UNREACH equ 3	60	ICMP_UNREACH equ 3
58	ICMP_UNREACH_NET equ 0 ; bad net	61	ICMP_UNREACH_NET equ 0 ; bad net
59	ICMP_UNREACH_HOST equ 1 ; bad host	62	ICMP_UNREACH_HOST equ 1 ; bad host
60	ICMP_UNREACH_PROTOCOL equ 2 ; bad protocol	63	ICMP_UNREACH_PROTOCOL equ 2 ; bad protocol
61	ICMP_UNREACH_PORT equ 3 ; bad port	64	ICMP_UNREACH_PORT equ 3 ; bad port
62	ICMP_UNREACH_NEEDFRAG equ 4 ; IP_DF caused drop	65	ICMP_UNREACH_NEEDFRAG equ 4 ; IP_DF caused drop
63	ICMP_UNREACH_SRCFAIL equ 5 ; src route failed	66	ICMP_UNREACH_SRCFAIL equ 5 ; src route failed
64	ICMP_UNREACH_NET_UNKNOWN equ 6 ; unknown net	67	ICMP_UNREACH_NET_UNKNOWN equ 6 ; unknown net
65	ICMP_UNREACH_HOST_UNKNOWN equ 7 ; unknown host	68	ICMP_UNREACH_HOST_UNKNOWN equ 7 ; unknown host
66	ICMP_UNREACH_ISOLATED equ 8 ; src host isolated	69	ICMP_UNREACH_ISOLATED equ 8 ; src host isolated
67	ICMP_UNREACH_NET_PROHIB equ 9 ; prohibited access	70	ICMP_UNREACH_NET_PROHIB equ 9 ; prohibited access
68	ICMP_UNREACH_HOST_PROHIB equ 10 ; ditto	71	ICMP_UNREACH_HOST_PROHIB equ 10 ; ditto
69	ICMP_UNREACH_TOSNET equ 11 ; bad tos for net	72	ICMP_UNREACH_TOSNET equ 11 ; bad tos for net
70	ICMP_UNREACH_TOSHOST equ 12 ; bad tos for host	73	ICMP_UNREACH_TOSHOST equ 12 ; bad tos for host
71	ICMP_UNREACH_FILTER_PROHIB equ 13 ; admin prohib	74	ICMP_UNREACH_FILTER_PROHIB equ 13 ; admin prohib
72	ICMP_UNREACH_HOST_PRECEDENCE equ 14 ; host prec vio.	75	ICMP_UNREACH_HOST_PRECEDENCE equ 14 ; host prec vio.
73	ICMP_UNREACH_PRECEDENCE_CUTOFF equ 15 ; prec cutoff	76	ICMP_UNREACH_PRECEDENCE_CUTOFF equ 15 ; prec cutoff
74		77
75	ICMP_SOURCEQUENCH equ 4 ; packet lost, slow down	78	ICMP_SOURCEQUENCH equ 4 ; packet lost, slow down
76		79
77	ICMP_REDIRECT equ 5 ; shorter route, codes:	80	ICMP_REDIRECT equ 5 ; shorter route, codes:
78	ICMP_REDIRECT_NET equ 0 ; for network	81	ICMP_REDIRECT_NET equ 0 ; for network
79	ICMP_REDIRECT_HOST equ 1 ; for host	82	ICMP_REDIRECT_HOST equ 1 ; for host
80	ICMP_REDIRECT_TOSNET equ 2 ; for tos and net	83	ICMP_REDIRECT_TOSNET equ 2 ; for tos and net
81	ICMP_REDIRECT_TOSHOST equ 3 ; for tos and host	84	ICMP_REDIRECT_TOSHOST equ 3 ; for tos and host
82		85
83	ICMP_ALTHOSTADDR equ 6 ; alternate host address	86	ICMP_ALTHOSTADDR equ 6 ; alternate host address
84	ICMP_ECHO equ 8 ; echo service	87	ICMP_ECHO equ 8 ; echo service
85	ICMP_ROUTERADVERT equ 9 ; router advertisement	88	ICMP_ROUTERADVERT equ 9 ; router advertisement
86	ICMP_ROUTERADVERT_NORMAL equ 0 ; normal advertisement	89	ICMP_ROUTERADVERT_NORMAL equ 0 ; normal advertisement
87	ICMP_ROUTERADVERT_NOROUTE_COMMON equ 16 ; selective routing	90	ICMP_ROUTERADVERT_NOROUTE_COMMON equ 16 ; selective routing
88		91
89	ICMP_ROUTERSOLICIT equ 10 ; router solicitation	92	ICMP_ROUTERSOLICIT equ 10 ; router solicitation
90	ICMP_TIMXCEED equ 11 ; time exceeded, code:	93	ICMP_TIMXCEED equ 11 ; time exceeded, code:
91	ICMP_TIMXCEED_INTRANS equ 0 ; ttl==0 in transit	94	ICMP_TIMXCEED_INTRANS equ 0 ; ttl==0 in transit
92	ICMP_TIMXCEED_REASS equ 1 ; ttl==0 in reass	95	ICMP_TIMXCEED_REASS equ 1 ; ttl==0 in reass
93		96
94	ICMP_PARAMPROB equ 12 ; ip header bad	97	ICMP_PARAMPROB equ 12 ; ip header bad
95	ICMP_PARAMPROB_ERRATPTR equ 0 ; error at param ptr	98	ICMP_PARAMPROB_ERRATPTR equ 0 ; error at param ptr
96	ICMP_PARAMPROB_OPTABSENT equ 1 ; req. opt. absent	99	ICMP_PARAMPROB_OPTABSENT equ 1 ; req. opt. absent
97	ICMP_PARAMPROB_LENGTH equ 2 ; bad length	100	ICMP_PARAMPROB_LENGTH equ 2 ; bad length
98		101
99	ICMP_TSTAMP equ 13 ; timestamp request	102	ICMP_TSTAMP equ 13 ; timestamp request
100	ICMP_TSTAMPREPLY equ 14 ; timestamp reply	103	ICMP_TSTAMPREPLY equ 14 ; timestamp reply
101	ICMP_IREQ equ 15 ; information request	104	ICMP_IREQ equ 15 ; information request
102	ICMP_IREQREPLY equ 16 ; information reply	105	ICMP_IREQREPLY equ 16 ; information reply
103	ICMP_MASKREQ equ 17 ; address mask request	106	ICMP_MASKREQ equ 17 ; address mask request
104	ICMP_MASKREPLY equ 18 ; address mask reply	107	ICMP_MASKREPLY equ 18 ; address mask reply
105	ICMP_TRACEROUTE equ 30 ; traceroute	108	ICMP_TRACEROUTE equ 30 ; traceroute
106	ICMP_DATACONVERR equ 31 ; data conversion error	109	ICMP_DATACONVERR equ 31 ; data conversion error
107	ICMP_MOBILE_REDIRECT equ 32 ; mobile host redirect	110	ICMP_MOBILE_REDIRECT equ 32 ; mobile host redirect
108	ICMP_IPV6_WHEREAREYOU equ 33 ; IPv6 where-are-you	111	ICMP_IPV6_WHEREAREYOU equ 33 ; IPv6 where-are-you
109	ICMP_IPV6_IAMHERE equ 34 ; IPv6 i-am-here	112	ICMP_IPV6_IAMHERE equ 34 ; IPv6 i-am-here
110	ICMP_MOBILE_REGREQUEST equ 35 ; mobile registration req	113	ICMP_MOBILE_REGREQUEST equ 35 ; mobile registration req
111	ICMP_MOBILE_REGREPLY equ 36 ; mobile registreation reply	114	ICMP_MOBILE_REGREPLY equ 36 ; mobile registreation reply
112	ICMP_SKIP equ 39 ; SKIP	115	ICMP_SKIP equ 39 ; SKIP
113		116
114	ICMP_PHOTURIS equ 40 ; Photuris	117	ICMP_PHOTURIS equ 40 ; Photuris
115	ICMP_PHOTURIS_UNKNOWN_INDEX equ 1 ; unknown sec index	118	ICMP_PHOTURIS_UNKNOWN_INDEX equ 1 ; unknown sec index
116	ICMP_PHOTURIS_AUTH_FAILED equ 2 ; auth failed	119	ICMP_PHOTURIS_AUTH_FAILED equ 2 ; auth failed
117	ICMP_PHOTURIS_DECRYPT_FAILED equ 3 ; decrypt failed	120	ICMP_PHOTURIS_DECRYPT_FAILED equ 3 ; decrypt failed
118		121
119		122
120	;***************************************************************************	123	;***************************************************************************
121	; Function	124	; Function
122	; icmp_rx [by Johnny_B]	125	; icmp_rx [by Johnny_B]
123	;	126	;
124	; Description	127	; Description
125	; ICMP protocol handler	128	; ICMP protocol handler
126	; This is a kernel function, called by ip_rx	129	; This is a kernel function, called by ip_rx
127	;	130	;
128	; IN:	131	; IN:
129	; buffer_number - # of IP-buffer. This buffer must be reused or marked as empty afterwards	132	; buffer_number - # of IP-buffer. This buffer must be reused or marked as empty afterwards
130	; IPPacketBase - IP_PACKET base address	133	; IPPacketBase - IP_PACKET base address
131	; IPHeaderLength - Header length of IP_PACKET	134	; IPHeaderLength - Header length of IP_PACKET
132	;	135	;
133	; OUT:	136	; OUT:
134	; EAX=not defined	137	; EAX=not defined
135	;	138	;
136	; All used registers will be saved	139	; All used registers will be saved
137	;	140	;
138	;***************************************************************************	141	;***************************************************************************
139	proc icmp_rx stdcall uses ebx esi edi,\	142	proc icmp_rx stdcall uses ebx esi edi,\
140	buffer_number:DWORD,IPPacketBase:DWORD,IPHeaderLength:DWORD	143	buffer_number:DWORD,IPPacketBase:DWORD,IPHeaderLength:DWORD
141		144
142	mov esi,[IPPacketBase] ;esi=IP_PACKET base address	145	mov esi,[IPPacketBase] ;esi=IP_PACKET base address
143	mov edi, esi	146	mov edi, esi
144	add edi,[IPHeaderLength] ;edi=ICMP_PACKET base address	147	add edi,[IPHeaderLength] ;edi=ICMP_PACKET base address
145		148
146	cmp byte[edi + ICMP_PACKET.Type], ICMP_ECHO ; Is this an echo request? discard if not	149	cmp byte[edi + ICMP_PACKET.Type], ICMP_ECHO ; Is this an echo request? discard if not
147	jz .icmp_echo	150	jz .icmp_echo
148		151
149	mov eax, [buffer_number]	152	mov eax, [buffer_number]
150	call freeBuff	153	call freeBuff
151	jmp .exit	154	jmp .exit
152		155
153	.icmp_echo:	156	.icmp_echo:
154		157
155	; swap the source and destination addresses	158	; swap the source and destination addresses
156	mov ecx, [esi + IP_PACKET.DestinationAddress]	159	mov ecx, [esi + IP_PACKET.DestinationAddress]
157	mov ebx, [esi + IP_PACKET.SourceAddress]	160	mov ebx, [esi + IP_PACKET.SourceAddress]
158	mov [esi + IP_PACKET.DestinationAddress], ebx	161	mov [esi + IP_PACKET.DestinationAddress], ebx
159	mov [esi + IP_PACKET.SourceAddress], ecx	162	mov [esi + IP_PACKET.SourceAddress], ecx
160		163
161	; recalculate the IP header checksum	164	; recalculate the IP header checksum
162	mov eax,[IPHeaderLength]	165	mov eax,[IPHeaderLength]
163	stdcall checksum_jb,esi,eax ;buf_ptr,buf_size	166	stdcall checksum_jb,esi,eax ;buf_ptr,buf_size
164		167
165	mov byte[esi + IP_PACKET.HeaderChecksum], ah	168	mov byte[esi + IP_PACKET.HeaderChecksum], ah
166	mov byte[esi + IP_PACKET.HeaderChecksum + 1], al ; ?? correct byte order?	169	mov byte[esi + IP_PACKET.HeaderChecksum + 1], al ; ?? correct byte order?
167		170
168	mov byte[edi + ICMP_PACKET.Type], ICMP_ECHOREPLY ; change the request to a response	171	mov byte[edi + ICMP_PACKET.Type], ICMP_ECHOREPLY ; change the request to a response
169	mov word[edi + ICMP_PACKET.Checksum], 0 ; clear ICMP checksum prior to re-calc	172	mov word[edi + ICMP_PACKET.Checksum], 0 ; clear ICMP checksum prior to re-calc
170		173
171	; Calculate the length of the ICMP data ( IP payload)	174	; Calculate the length of the ICMP data ( IP payload)
172	xor eax, eax	175	xor eax, eax
173	mov ah, byte[esi + IP_PACKET.TotalLength]	176	mov ah, byte[esi + IP_PACKET.TotalLength]
174	mov al, byte[esi + IP_PACKET.TotalLength + 1]	177	mov al, byte[esi + IP_PACKET.TotalLength + 1]
175	sub ax, word[IPHeaderLength] ;ax=ICMP-packet length	178	sub ax, word[IPHeaderLength] ;ax=ICMP-packet length
176		179
177	stdcall checksum_jb,edi,eax ;buf_ptr,buf_size	180	stdcall checksum_jb,edi,eax ;buf_ptr,buf_size
178		181
179	mov byte[edi + ICMP_PACKET.Checksum], ah	182	mov byte[edi + ICMP_PACKET.Checksum], ah
180	mov byte[edi + ICMP_PACKET.Checksum + 1], al	183	mov byte[edi + ICMP_PACKET.Checksum + 1], al
181		184
182	; Queue packet for transmission	185	; Queue packet for transmission
183	mov ebx, [buffer_number]	186	mov ebx, [buffer_number]
184	mov eax, NET1OUT_QUEUE	187	mov eax, NET1OUT_QUEUE
185	call queue	188	call queue
186		189
187	.exit:	190	.exit:
188	ret	191	ret
189	endp	192	endp