/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ /* ICMP for IP v4 and v6 */enum{	/* Packet Types, icmp v4 (rfc 792) */	EchoReply	= 0,	Unreachable	= 3,	SrcQuench	= 4,	Redirect	= 5,	EchoRequest	= 8,	TimeExceed	= 11,	InParmProblem	= 12,	Timestamp	= 13,	TimestampReply	= 14,	InfoRequest	= 15,	InfoReply	= 16,	AddrMaskRequest = 17,	AddrMaskReply   = 18,	Traceroute	= 30,	IPv6WhereAreYou	= 33,	IPv6IAmHere	= 34, 	/* packet types, icmp v6 (rfc 2463) */         /* error messages */	UnreachableV6	= 1,	PacketTooBigV6	= 2,	TimeExceedV6	= 3,	ParamProblemV6	= 4,         /* informational messages (rfc 2461 also) */	EchoRequestV6	= 128,	EchoReplyV6	= 129,	RouterSolicit	= 133,	RouterAdvert	= 134,	NbrSolicit	= 135,	NbrAdvert	= 136,	RedirectV6	= 137, 	Maxtype6	= 137, 	ICMP_HDRSIZE	= 8,}; typedef struct Ip4hdr Ip4hdr;struct Ip4hdr{	uchar	vihl;		/* Version and header length */	uchar	tos;		/* Type of service */	uchar	length[2];	/* packet length */	uchar	id[2];		/* Identification */	uchar	frag[2];	/* Fragment information */	uchar	ttl;		/* Time to live */	uchar	proto;		/* Protocol */	uchar	ipcksum[2];	/* Header checksum */	uchar	src[4];		/* Ipv4 source */	uchar	dst[4];		/* Ipv4 destination */ 	uchar	data[];}; // #define IP4HDRSZ offsetof(Ip4hdr, data[0]) /* the icmp payload has the same format in v4 and v6 */typedef struct Icmphdr Icmphdr;struct Icmphdr {	uchar	type;	uchar	code;	uchar	cksum[2];	uchar	icmpid[2];	uchar	seq[2];	uchar	data[];}; // #define ICMPHDRSZ offsetof(Icmphdr, data[0])