##       Software from the book "Inferno Programming with Limbo"#       published by John Wiley & Sons, January 2003.##       p. Stanley-Marbell <pip@gemusehaken.org>#implement XFmt; include "sys.m";include "xsniff.m"; sys	: Sys; Pkt : adt{	data	: array of byte; 	srcip	: array of byte;	dstip	: array of byte;	ipvers	: int;	proto	: int;	nexthdr	: int;	ttl		: int;}; PROTO_STRINGS 	:= array [] of {	"",	"ICMP", 	"IGMP", 	"","","",	"TCP", 	"","","","","","","","","","",	"UDP"}; IPv4	: con 4;IPv6	: con 6; fmt (data : array of byte, args : list of string) : (int, string){	sys = load Sys Sys->PATH; 	#	If our module instance ID has not been set, do it	if (ID == nil)	{		ID = "ether0800";	} 	pktptr  := ref Pkt(data,				array [16] of byte, 				array [16] of byte, 				0, 0, 0, 0); 	if (decode(pktptr) < 0)	{		return (-1, "Bad packet passed to Ether0800Fmt");	} 	sys->print("\tIP version:	[%d]\n",			pktptr.ipvers);	sys->print("\tPROTO:		[%s]\n",			PROTO_STRINGS[pktptr.proto%(len PROTO_STRINGS)]);	sys->print("\tNEXTHDR:		[%d]\n",			pktptr.nexthdr);	sys->print("\tSource IP:	[%s]\n",			addrbytes2string(pktptr.srcip, pktptr.ipvers));	sys->print("\tDestination IP:	[%s]\n",			addrbytes2string(pktptr.dstip, pktptr.ipvers));	sys->print("\tTTL:		[%d]\n",			pktptr.ttl); 	return (0, nil);} decode(pktptr : ref Pkt) : int{	pktptr.ipvers = int (pktptr.data[0] >> 4); 	case (pktptr.ipvers)	{		IPv4	=>		{			pktptr.proto = int pktptr.data[9];			pktptr.srcip[12:] = pktptr.data[12:16];			pktptr.dstip[12:] = pktptr.data[16:20];			pktptr.ttl = int pktptr.data[8]; 			return 0;		} 		IPv6	=>		{			pktptr.nexthdr = int pktptr.data[6]; 			return 0;		} 		*	=>		{			#	Unknown IP version		}	} 	return -1;} addrbytes2string(addr : array of byte, ipvers : int) : string{	case (ipvers)	{		IPv4	=>		{			return (sys->sprint("%d.%d.%d.%d", int addr[12],						int addr[13],						int addr[14],						int addr[15]));		}				IPv6	=>		{			return  (sys->sprint("%4x:%4x:%4x:%4x:%4x:%4x:%4x:%4x",						int (addr[1] + addr[2] << 8),						int (addr[3] + addr[4] << 8),						int (addr[5] + addr[6] << 8),						int (addr[7] + addr[8] << 8),						int (addr[9] + addr[10] << 8),						int (addr[11] + addr[12] << 8),						int (addr[13] + addr[14] << 8),						int (addr[15] + addr[16] << 8)));		} 		*	=>		{			#	Unknown IP version		}	} 	return "Unknown IP Version";}