// See the file "COPYING" in the main distribution directory for copyright.

#include "zeek/packet_analysis/protocol/icmp/ICMP.h"

#include <netinet/icmp6.h>

#include "zeek/RunState.h"
#include "zeek/Conn.h"
#include "zeek/Reporter.h"
#include "zeek/Desc.h"
#include "zeek/Val.h"
#include "zeek/analyzer/Manager.h"
#include "zeek/session/Manager.h"
#include "zeek/analyzer/protocol/conn-size/ConnSize.h"

#include "zeek/ZeekString.h"

#include "zeek/packet_analysis/protocol/icmp/events.bif.h"

enum ICMP_EndpointState {
	ICMP_INACTIVE,	// no packet seen
	ICMP_ACTIVE,	// packets seen
};

using namespace zeek::packet_analysis::ICMP;
using namespace zeek::packet_analysis::IP;

ICMPAnalyzer::ICMPAnalyzer() : IPBasedAnalyzer("ICMP", TRANSPORT_ICMP, ICMP_PORT_MASK, false)
	{
	}

SessionAdapter* ICMPAnalyzer::MakeSessionAdapter(Connection* conn)
	{
	auto* root = new ICMPSessionAdapter(conn);
	root->SetParent(this);
	conn->SetInactivityTimeout(zeek::detail::icmp_inactivity_timeout);

	return root;
	}

bool ICMPAnalyzer::BuildConnTuple(size_t len, const uint8_t* data, Packet* packet,
                                  ConnTuple& tuple)
	{
	if ( ! CheckHeaderTrunc(ICMP_MINLEN, len, packet) )
		return false;

	tuple.src_addr = packet->ip_hdr->SrcAddr();
	tuple.dst_addr = packet->ip_hdr->DstAddr();
	tuple.proto = TRANSPORT_ICMP;

	const struct icmp* icmpp = (const struct icmp *) data;
	tuple.src_port = htons(icmpp->icmp_type);

	if ( packet->proto == IPPROTO_ICMP )
		tuple.dst_port = htons(ICMP4_counterpart(icmpp->icmp_type, icmpp->icmp_code, tuple.is_one_way));
	else if ( packet->proto == IPPROTO_ICMPV6 )
		tuple.dst_port = htons(ICMP6_counterpart(icmpp->icmp_type, icmpp->icmp_code, tuple.is_one_way));
	else
		reporter->InternalError("Reached ICMP packet analyzer with unknown packet protocol %x",
		                        packet->proto);

	return true;
	}

void ICMPAnalyzer::DeliverPacket(Connection* c, double t, bool is_orig, int remaining, Packet* pkt)
	{
	auto* adapter = static_cast<ICMPSessionAdapter*>(c->GetSessionAdapter());

	const u_char* data = pkt->ip_hdr->Payload();
	int len = pkt->ip_hdr->PayloadLen();

	if ( packet_contents && len > 0 )
		adapter->PacketContents(data + 8, std::min(len, remaining) - 8);

	const struct icmp* icmpp = (const struct icmp*) data;
	const std::unique_ptr<IP_Hdr>& ip = pkt->ip_hdr;

	if ( ! zeek::detail::ignore_checksums &&
	     ! zeek::id::find_val<TableVal>("ignore_checksums_nets")->Contains(ip->IPHeaderSrcAddr()) &&
	     remaining >= len )
		{
		int chksum = 0;

		switch ( ip->NextProto() )
		{
		case IPPROTO_ICMP:
			chksum = icmp_checksum(icmpp, len);
			break;

		case IPPROTO_ICMPV6:
			chksum = icmp6_checksum(icmpp, ip.get(), len);
			break;

		default:
			reporter->Error("unexpected IP proto in ICMP analyzer: %d", ip->NextProto());
			return;
		}

		if ( chksum != 0xffff )
			{
			adapter->Weird("bad_ICMP_checksum");
			return;
			}
		}

	c->SetLastTime(run_state::current_timestamp);
	adapter->InitEndpointMatcher(ip.get(), len, is_orig);

	// Move past common portion of ICMP header.
	data += 8;
	remaining -= 8;
	len -= 8;

	adapter->UpdateLength(is_orig, len);

	if ( ip->NextProto() == IPPROTO_ICMP )
		NextICMP4(run_state::current_timestamp, icmpp, len, remaining, data, ip.get(), adapter);
	else if ( ip->NextProto() == IPPROTO_ICMPV6 )
		NextICMP6(run_state::current_timestamp, icmpp, len, remaining, data, ip.get(), adapter);
	else
		{
		reporter->Error("expected ICMP as IP packet's protocol, got %d", ip->NextProto());
		return;
		}

	ForwardPacket(len, data, pkt);

	if ( remaining >= len )
		adapter->ForwardPacket(len, data, is_orig, -1, ip.get(), remaining);

	adapter->MatchEndpoint(data, len, is_orig);
	}

void ICMPAnalyzer::NextICMP4(double t, const struct icmp* icmpp, int len, int caplen,
                             const u_char*& data, const IP_Hdr* ip_hdr,
                             ICMPSessionAdapter* adapter)
	{
	switch ( icmpp->icmp_type )
		{
		case ICMP_ECHO:
		case ICMP_ECHOREPLY:
			Echo(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;

		case ICMP_UNREACH:
		case ICMP_TIMXCEED:
			Context4(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;

		default:
			ICMP_Sent(icmpp, len, caplen, 0, data, ip_hdr, adapter);
			break;
		}
	}

void ICMPAnalyzer::NextICMP6(double t, const struct icmp* icmpp, int len, int caplen,
                             const u_char*& data, const IP_Hdr* ip_hdr,
                             ICMPSessionAdapter* adapter)
	{
	switch ( icmpp->icmp_type )
		{
		// Echo types.
		case ICMP6_ECHO_REQUEST:
		case ICMP6_ECHO_REPLY:
			Echo(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;

		// Error messages all have the same structure for their context,
		// and are handled by the same function.
		case ICMP6_PARAM_PROB:
		case ICMP6_TIME_EXCEEDED:
		case ICMP6_PACKET_TOO_BIG:
		case ICMP6_DST_UNREACH:
			Context6(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;

		// Router related messages.
		case ND_REDIRECT:
			Redirect(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;
		case ND_ROUTER_ADVERT:
			RouterAdvert(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;
		case ND_NEIGHBOR_ADVERT:
			NeighborAdvert(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;
		case ND_NEIGHBOR_SOLICIT:
			NeighborSolicit(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;
		case ND_ROUTER_SOLICIT:
			RouterSolicit(t, icmpp, len, caplen, data, ip_hdr, adapter);
			break;
		case ICMP6_ROUTER_RENUMBERING:
			ICMP_Sent(icmpp, len, caplen, 1, data, ip_hdr, adapter);
			break;

#if 0
		// Currently not specifically implemented.
		case MLD_LISTENER_QUERY:
		case MLD_LISTENER_REPORT:
		case MLD_LISTENER_REDUCTION:
#endif
		default:
			// Error messages (i.e., ICMPv6 type < 128) all have
			// the same structure for their context, and are
			// handled by the same function.
			if ( icmpp->icmp_type < 128 )
				Context6(t, icmpp, len, caplen, data, ip_hdr, adapter);
			else
				ICMP_Sent(icmpp, len, caplen, 1, data, ip_hdr, adapter);
			break;
		}
	}

void ICMPAnalyzer::ICMP_Sent(const struct icmp* icmpp, int len, int caplen,
                             int icmpv6, const u_char* data, const IP_Hdr* ip_hdr,
                             ICMPSessionAdapter* adapter)
    {
	if ( icmp_sent )
		adapter->EnqueueConnEvent(icmp_sent, adapter->ConnVal(),
		                          BuildInfo(icmpp, len, icmpv6, ip_hdr));

	if ( icmp_sent_payload )
		{
		String* payload = new String(data, std::min(len, caplen), false);

		adapter->EnqueueConnEvent(icmp_sent_payload, adapter->ConnVal(),
		                          BuildInfo(icmpp, len, icmpv6, ip_hdr),
		                          make_intrusive<StringVal>(payload));
		}
	}

zeek::RecordValPtr ICMPAnalyzer::BuildInfo(const struct icmp* icmpp, int len,
                                      bool icmpv6, const IP_Hdr* ip_hdr)
	{
	static auto icmp_info = id::find_type<RecordType>("icmp_info");
	auto rval = make_intrusive<zeek::RecordVal>(icmp_info);
	rval->Assign(0, val_mgr->Bool(icmpv6));
	rval->Assign(1, val_mgr->Count(icmpp->icmp_type));
	rval->Assign(2, val_mgr->Count(icmpp->icmp_code));
	rval->Assign(3, val_mgr->Count(len));
	rval->Assign(4, val_mgr->Count(ip_hdr->TTL()));
	return rval;
	}

TransportProto ICMPAnalyzer::GetContextProtocol(const IP_Hdr* ip_hdr, uint32_t* src_port, uint32_t* dst_port)
	{
	const u_char* transport_hdr;
	uint32_t ip_hdr_len = ip_hdr->HdrLen();
	bool ip4 = ip_hdr->IP4_Hdr();

	if ( ip4 )
		transport_hdr = ((u_char *) ip_hdr->IP4_Hdr() + ip_hdr_len);
	else
		transport_hdr = ((u_char *) ip_hdr->IP6_Hdr() + ip_hdr_len);

	TransportProto proto;

	switch ( ip_hdr->NextProto() ) {
	case 1:		proto = TRANSPORT_ICMP; break;
	case 6:		proto = TRANSPORT_TCP; break;
	case 17:	proto = TRANSPORT_UDP; break;
	case 58:	proto = TRANSPORT_ICMP; break;
	default:	proto = TRANSPORT_UNKNOWN; break;
	}

	switch ( proto ) {
	case TRANSPORT_ICMP:
		{
		const struct icmp* icmpp =
			(const struct icmp *) transport_hdr;
		bool is_one_way;	// dummy
		*src_port = ntohs(icmpp->icmp_type);

		if ( ip4 )
			*dst_port = ntohs(ICMP4_counterpart(icmpp->icmp_type,
					icmpp->icmp_code, is_one_way));
		else
			*dst_port = ntohs(ICMP6_counterpart(icmpp->icmp_type,
					icmpp->icmp_code, is_one_way));

		break;
		}

	case TRANSPORT_TCP:
		{
		const struct tcphdr* tp =
			(const struct tcphdr *) transport_hdr;
		*src_port = ntohs(tp->th_sport);
		*dst_port = ntohs(tp->th_dport);
		break;
		}

	case TRANSPORT_UDP:
		{
		const struct udphdr* up =
			(const struct udphdr *) transport_hdr;
		*src_port = ntohs(up->uh_sport);
		*dst_port = ntohs(up->uh_dport);
		break;
		}

	default:
		*src_port = *dst_port = ntohs(0);
		break;
	}

	return proto;
	}

zeek::RecordValPtr ICMPAnalyzer::ExtractICMP4Context(int len, const u_char*& data)
	{
	const IP_Hdr ip_hdr_data((const struct ip*) data, false);
	const IP_Hdr* ip_hdr = &ip_hdr_data;

	uint32_t ip_hdr_len = ip_hdr->HdrLen();

	uint32_t ip_len, frag_offset;
	TransportProto proto = TRANSPORT_UNKNOWN;
	int DF, MF, bad_hdr_len, bad_checksum;
	IPAddr src_addr, dst_addr;
	uint32_t src_port, dst_port;

	if ( len < (int)sizeof(struct ip) || ip_hdr_len > uint32_t(len) )
		{
		// We don't have an entire IP header.
		bad_hdr_len = 1;
		ip_len = frag_offset = 0;
		DF = MF = bad_checksum = 0;
		src_port = dst_port = 0;
		}

	else
		{
		bad_hdr_len = 0;
		ip_len = ip_hdr->TotalLen();
		bad_checksum = ! run_state::current_pkt->l3_checksummed &&
		  (detail::in_cksum(reinterpret_cast<const uint8_t*>(ip_hdr->IP4_Hdr()),
		                    ip_hdr_len) != 0xffff);

		src_addr = ip_hdr->SrcAddr();
		dst_addr = ip_hdr->DstAddr();

		DF = ip_hdr->DF();
		MF = ip_hdr->MF();
		frag_offset = ip_hdr->FragOffset();

		if ( uint32_t(len) >= ip_hdr_len + 4 )
			proto = GetContextProtocol(ip_hdr, &src_port, &dst_port);
		else
			{
			// 4 above is the magic number meaning that both
			// port numbers are included in the ICMP.
			src_port = dst_port = 0;
			bad_hdr_len = 1;
			}
		}

	static auto icmp_context = id::find_type<RecordType>("icmp_context");
	auto iprec = make_intrusive<zeek::RecordVal>(icmp_context);
	auto id_val = make_intrusive<zeek::RecordVal>(id::conn_id);

	id_val->Assign(0, make_intrusive<AddrVal>(src_addr));
	id_val->Assign(1, val_mgr->Port(src_port, proto));
	id_val->Assign(2, make_intrusive<AddrVal>(dst_addr));
	id_val->Assign(3, val_mgr->Port(dst_port, proto));

	iprec->Assign(0, std::move(id_val));
	iprec->Assign(1, val_mgr->Count(ip_len));
	iprec->Assign(2, val_mgr->Count(proto));
	iprec->Assign(3, val_mgr->Count(frag_offset));
	iprec->Assign(4, val_mgr->Bool(bad_hdr_len));
	iprec->Assign(5, val_mgr->Bool(bad_checksum));
	iprec->Assign(6, val_mgr->Bool(MF));
	iprec->Assign(7, val_mgr->Bool(DF));

	return iprec;
	}

zeek::RecordValPtr ICMPAnalyzer::ExtractICMP6Context(int len, const u_char*& data)
	{
	int DF = 0, MF = 0, bad_hdr_len = 0;
	TransportProto proto = TRANSPORT_UNKNOWN;

	IPAddr src_addr;
	IPAddr dst_addr;
	uint32_t ip_len, frag_offset = 0;
	uint32_t src_port, dst_port;

	if ( len < (int)sizeof(struct ip6_hdr) )
		{
		bad_hdr_len = 1;
		ip_len = 0;
		src_port = dst_port = 0;
		}
	else
		{
		const IP_Hdr ip_hdr_data((const struct ip6_hdr*) data, false, len);
		const IP_Hdr* ip_hdr = &ip_hdr_data;

		ip_len = ip_hdr->TotalLen();
		src_addr = ip_hdr->SrcAddr();
		dst_addr = ip_hdr->DstAddr();
		frag_offset = ip_hdr->FragOffset();
		MF = ip_hdr->MF();
		DF = ip_hdr->DF();

		if ( uint32_t(len) >= uint32_t(ip_hdr->HdrLen() + 4) )
			proto = GetContextProtocol(ip_hdr, &src_port, &dst_port);
		else
			{
			// 4 above is the magic number meaning that both
			// port numbers are included in the ICMP.
			src_port = dst_port = 0;
			bad_hdr_len = 1;
			}
		}

	static auto icmp_context = id::find_type<RecordType>("icmp_context");
	auto iprec = make_intrusive<zeek::RecordVal>(icmp_context);
	auto id_val = make_intrusive<zeek::RecordVal>(id::conn_id);

	id_val->Assign(0, make_intrusive<AddrVal>(src_addr));
	id_val->Assign(1, val_mgr->Port(src_port, proto));
	id_val->Assign(2, make_intrusive<AddrVal>(dst_addr));
	id_val->Assign(3, val_mgr->Port(dst_port, proto));

	iprec->Assign(0, std::move(id_val));
	iprec->Assign(1, val_mgr->Count(ip_len));
	iprec->Assign(2, val_mgr->Count(proto));
	iprec->Assign(3, val_mgr->Count(frag_offset));
	iprec->Assign(4, val_mgr->Bool(bad_hdr_len));
	// bad_checksum is always false since IPv6 layer doesn't have a checksum.
	iprec->Assign(5, val_mgr->False());
	iprec->Assign(6, val_mgr->Bool(MF));
	iprec->Assign(7, val_mgr->Bool(DF));

	return iprec;
	}

void ICMPAnalyzer::Echo(double t, const struct icmp* icmpp, int len,
                        int caplen, const u_char*& data, const IP_Hdr* ip_hdr,
                        ICMPSessionAdapter* adapter)
	{
	// For handling all Echo related ICMP messages
	EventHandlerPtr f = nullptr;

	if ( ip_hdr->NextProto() == IPPROTO_ICMPV6 )
		f = (icmpp->icmp_type == ICMP6_ECHO_REQUEST)
			? icmp_echo_request : icmp_echo_reply;
	else
		f = (icmpp->icmp_type == ICMP_ECHO)
			? icmp_echo_request : icmp_echo_reply;

	if ( ! f )
		return;

	int iid = ntohs(icmpp->icmp_hun.ih_idseq.icd_id);
	int iseq = ntohs(icmpp->icmp_hun.ih_idseq.icd_seq);

	String* payload = new String(data, caplen, false);

	adapter->EnqueueConnEvent(f,
		adapter->ConnVal(),
		BuildInfo(icmpp, len, ip_hdr->NextProto() != IPPROTO_ICMP, ip_hdr),
		val_mgr->Count(iid),
		val_mgr->Count(iseq),
		make_intrusive<StringVal>(payload)
	);
	}


void ICMPAnalyzer::RouterAdvert(double t, const struct icmp* icmpp, int len,
                                int caplen, const u_char*& data, const IP_Hdr* ip_hdr,
                                ICMPSessionAdapter* adapter)
	{
	EventHandlerPtr f = icmp_router_advertisement;

	if ( ! f )
		return;

	uint32_t reachable = 0, retrans = 0;

	if ( caplen >= (int)sizeof(reachable) )
		memcpy(&reachable, data, sizeof(reachable));

	if ( caplen >= (int)sizeof(reachable) + (int)sizeof(retrans) )
		memcpy(&retrans, data + sizeof(reachable), sizeof(retrans));

	int opt_offset = sizeof(reachable) + sizeof(retrans);

	adapter->EnqueueConnEvent(f,
		adapter->ConnVal(),
		BuildInfo(icmpp, len, 1, ip_hdr),
		val_mgr->Count(icmpp->icmp_num_addrs), // Cur Hop Limit
		val_mgr->Bool(icmpp->icmp_wpa & 0x80), // Managed
		val_mgr->Bool(icmpp->icmp_wpa & 0x40), // Other
		val_mgr->Bool(icmpp->icmp_wpa & 0x20), // Home Agent
		val_mgr->Count((icmpp->icmp_wpa & 0x18)>>3), // Pref
		val_mgr->Bool(icmpp->icmp_wpa & 0x04), // Proxy
		val_mgr->Count(icmpp->icmp_wpa & 0x02), // Reserved
		make_intrusive<IntervalVal>((double)ntohs(icmpp->icmp_lifetime), Seconds),
		make_intrusive<IntervalVal>((double)ntohl(reachable), Milliseconds),
		make_intrusive<IntervalVal>((double)ntohl(retrans), Milliseconds),
		BuildNDOptionsVal(caplen - opt_offset, data + opt_offset, adapter)
	);
	}


void ICMPAnalyzer::NeighborAdvert(double t, const struct icmp* icmpp, int len,
                                  int caplen, const u_char*& data, const IP_Hdr* ip_hdr,
                                  ICMPSessionAdapter* adapter)
	{
	EventHandlerPtr f = icmp_neighbor_advertisement;

	if ( ! f )
		return;

	IPAddr tgtaddr;

	if ( caplen >= (int)sizeof(in6_addr) )
		tgtaddr = IPAddr(*((const in6_addr*)data));

	int opt_offset = sizeof(in6_addr);

	adapter->EnqueueConnEvent(f,
		adapter->ConnVal(),
		BuildInfo(icmpp, len, 1, ip_hdr),
		val_mgr->Bool(icmpp->icmp_num_addrs & 0x80), // Router
		val_mgr->Bool(icmpp->icmp_num_addrs & 0x40), // Solicited
		val_mgr->Bool(icmpp->icmp_num_addrs & 0x20), // Override
		make_intrusive<AddrVal>(tgtaddr),
		BuildNDOptionsVal(caplen - opt_offset, data + opt_offset, adapter)
	);
	}


void ICMPAnalyzer::NeighborSolicit(double t, const struct icmp* icmpp, int len,
                                   int caplen, const u_char*& data, const IP_Hdr* ip_hdr,
                                   ICMPSessionAdapter* adapter)
	{
	EventHandlerPtr f = icmp_neighbor_solicitation;

	if ( ! f )
		return;

	IPAddr tgtaddr;

	if ( caplen >= (int)sizeof(in6_addr) )
		tgtaddr = IPAddr(*((const in6_addr*)data));

	int opt_offset = sizeof(in6_addr);

	adapter->EnqueueConnEvent(f,
		adapter->ConnVal(),
		BuildInfo(icmpp, len, 1, ip_hdr),
		make_intrusive<AddrVal>(tgtaddr),
		BuildNDOptionsVal(caplen - opt_offset, data + opt_offset, adapter)
	);
	}


void ICMPAnalyzer::Redirect(double t, const struct icmp* icmpp, int len,
                            int caplen, const u_char*& data, const IP_Hdr* ip_hdr,
                            ICMPSessionAdapter* adapter)
	{
	EventHandlerPtr f = icmp_redirect;

	if ( ! f )
		return;

	IPAddr tgtaddr, dstaddr;

	if ( caplen >= (int)sizeof(in6_addr) )
		tgtaddr = IPAddr(*((const in6_addr*)data));

	if ( caplen >= 2 * (int)sizeof(in6_addr) )
		dstaddr = IPAddr(*((const in6_addr*)(data + sizeof(in6_addr))));

	int opt_offset = 2 * sizeof(in6_addr);

	adapter->EnqueueConnEvent(f,
		adapter->ConnVal(),
		BuildInfo(icmpp, len, 1, ip_hdr),
		make_intrusive<AddrVal>(tgtaddr),
		make_intrusive<AddrVal>(dstaddr),
		BuildNDOptionsVal(caplen - opt_offset, data + opt_offset, adapter)
	);
	}


void ICMPAnalyzer::RouterSolicit(double t, const struct icmp* icmpp, int len,
                                 int caplen, const u_char*& data, const IP_Hdr* ip_hdr,
                                 ICMPSessionAdapter* adapter)
	{
	EventHandlerPtr f = icmp_router_solicitation;

	if ( ! f )
		return;

	adapter->EnqueueConnEvent(f,
		adapter->ConnVal(),
		BuildInfo(icmpp, len, 1, ip_hdr),
		BuildNDOptionsVal(caplen, data, adapter)
	);
	}


void ICMPAnalyzer::Context4(double t, const struct icmp* icmpp, int len,
                            int caplen, const u_char*& data, const IP_Hdr* ip_hdr,
                            ICMPSessionAdapter* adapter)
	{
	EventHandlerPtr f = nullptr;

	switch ( icmpp->icmp_type )
		{
		case ICMP_UNREACH:
			f = icmp_unreachable;
			break;

		case ICMP_TIMXCEED:
			f = icmp_time_exceeded;
			break;
		}

	if ( f )
		adapter->EnqueueConnEvent(f,
			adapter->ConnVal(),
			BuildInfo(icmpp, len, 0, ip_hdr),
			val_mgr->Count(icmpp->icmp_code),
			ExtractICMP4Context(caplen, data)
		);
	}


void ICMPAnalyzer::Context6(double t, const struct icmp* icmpp, int len,
                            int caplen, const u_char*& data, const IP_Hdr* ip_hdr,
                            ICMPSessionAdapter* adapter)
	{
	EventHandlerPtr f = nullptr;

	switch ( icmpp->icmp_type )
		{
		case ICMP6_DST_UNREACH:
			f = icmp_unreachable;
			break;

		case ICMP6_PARAM_PROB:
			f = icmp_parameter_problem;
			break;

		case ICMP6_TIME_EXCEEDED:
			f = icmp_time_exceeded;
			break;

		case ICMP6_PACKET_TOO_BIG:
			f = icmp_packet_too_big;
			break;

		default:
			f = icmp_error_message;
			break;
		}

	if ( f )
		adapter->EnqueueConnEvent(f,
			adapter->ConnVal(),
			BuildInfo(icmpp, len, 1, ip_hdr),
			val_mgr->Count(icmpp->icmp_code),
			ExtractICMP6Context(caplen, data)
		);
	}

zeek::VectorValPtr ICMPAnalyzer::BuildNDOptionsVal(int caplen, const u_char* data,
                                                   ICMPSessionAdapter* adapter)
	{
	static auto icmp6_nd_option_type = id::find_type<RecordType>("icmp6_nd_option");
	static auto icmp6_nd_prefix_info_type = id::find_type<RecordType>("icmp6_nd_prefix_info");

	auto vv = make_intrusive<zeek::VectorVal>(
		id::find_type<VectorType>("icmp6_nd_options"));

	while ( caplen > 0 )
		{
		// Must have at least type & length to continue parsing options.
		if ( caplen < 2 )
			{
			adapter->Weird("truncated_ICMPv6_ND_options");
			break;
			}

		uint8_t type = *((const uint8_t*)data);
		uint16_t length = *((const uint8_t*)(data + 1));

		if ( length == 0 )
			{
			adapter->Weird("zero_length_ICMPv6_ND_option");
			break;
			}

		auto rv = make_intrusive<zeek::RecordVal>(icmp6_nd_option_type);
		rv->Assign(0, val_mgr->Count(type));
		rv->Assign(1, val_mgr->Count(length));

		// Adjust length to be in units of bytes, exclude type/length fields.
		length = length * 8 - 2;

		data += 2;
		caplen -= 2;

		bool set_payload_field = false;

		// Only parse out known options that are there in full.
		switch ( type ) {
		case 1:
		case 2:
			// Source/Target Link-layer Address option
			{
			if ( caplen >= length )
				{
				String* link_addr = new String(data, length, false);
				rv->Assign(2, make_intrusive<StringVal>(link_addr));
				}
			else
				set_payload_field = true;

			break;
			}

		case 3:
			// Prefix Information option
			{
			if ( caplen >= 30 )
				{
				auto info = make_intrusive<zeek::RecordVal>(icmp6_nd_prefix_info_type);
				uint8_t prefix_len = *((const uint8_t*)(data));
				bool L_flag = (*((const uint8_t*)(data + 1)) & 0x80) != 0;
				bool A_flag = (*((const uint8_t*)(data + 1)) & 0x40) != 0;
				uint32_t valid_life = *((const uint32_t*)(data + 2));
				uint32_t prefer_life = *((const uint32_t*)(data + 6));
				in6_addr prefix = *((const in6_addr*)(data + 14));
				info->Assign(0, val_mgr->Count(prefix_len));
				info->Assign(1, val_mgr->Bool(L_flag));
				info->Assign(2, val_mgr->Bool(A_flag));
				info->Assign(3, make_intrusive<IntervalVal>((double)ntohl(valid_life), Seconds));
				info->Assign(4, make_intrusive<IntervalVal>((double)ntohl(prefer_life), Seconds));
				info->Assign(5, make_intrusive<AddrVal>(IPAddr(prefix)));
				rv->Assign(3, std::move(info));
				}

			else
				set_payload_field = true;
			break;
			}

		case 4:
			// Redirected Header option
			{
			if ( caplen >= length )
				{
				const u_char* hdr = data + 6;
				rv->Assign(4, ExtractICMP6Context(length - 6, hdr));
				}

			else
				set_payload_field = true;

			break;
			}

		case 5:
			// MTU option
			{
			if ( caplen >= 6 )
				rv->Assign(5, val_mgr->Count(ntohl(*((const uint32_t*)(data + 2)))));
			else
				set_payload_field = true;

			break;
			}

		default:
			{
			set_payload_field = true;
			break;
			}
		}

		if ( set_payload_field )
			{
			String* payload = new String(data, std::min((int)length, caplen), false);
			rv->Assign(6, make_intrusive<StringVal>(payload));
			}

		data += length;
		caplen -= length;

		vv->Assign(vv->Size(), std::move(rv));
		}

	return vv;
	}

int ICMPAnalyzer::ICMP4_counterpart(int icmp_type, int icmp_code, bool& is_one_way)
	{
	is_one_way = false;

	// Return the counterpart type if one exists.  This allows us
	// to track corresponding ICMP requests/replies.
	// Note that for the two-way ICMP messages, icmp_code is
	// always 0 (RFC 792).
	switch ( icmp_type ) {
	case ICMP_ECHO:			return ICMP_ECHOREPLY;
	case ICMP_ECHOREPLY:		return ICMP_ECHO;

	case ICMP_TSTAMP:		return ICMP_TSTAMPREPLY;
	case ICMP_TSTAMPREPLY:		return ICMP_TSTAMP;

	case ICMP_IREQ:			return ICMP_IREQREPLY;
	case ICMP_IREQREPLY:		return ICMP_IREQ;

	case ICMP_ROUTERSOLICIT:	return ICMP_ROUTERADVERT;
	case ICMP_ROUTERADVERT:	return ICMP_ROUTERSOLICIT;

	case ICMP_MASKREQ:		return ICMP_MASKREPLY;
	case ICMP_MASKREPLY:		return ICMP_MASKREQ;

	default:			is_one_way = true; return icmp_code;
	}
	}

int ICMPAnalyzer::ICMP6_counterpart(int icmp_type, int icmp_code, bool& is_one_way)
	{
	is_one_way = false;

	switch ( icmp_type ) {
	case ICMP6_ECHO_REQUEST:		return ICMP6_ECHO_REPLY;
	case ICMP6_ECHO_REPLY:			return ICMP6_ECHO_REQUEST;

	case ND_ROUTER_SOLICIT:			return ND_ROUTER_ADVERT;
	case ND_ROUTER_ADVERT:			return ND_ROUTER_SOLICIT;

	case ND_NEIGHBOR_SOLICIT:		return ND_NEIGHBOR_ADVERT;
	case ND_NEIGHBOR_ADVERT:		return ND_NEIGHBOR_SOLICIT;

	case MLD_LISTENER_QUERY: 		return MLD_LISTENER_REPORT;
	case MLD_LISTENER_REPORT:		return MLD_LISTENER_QUERY;

	// ICMP node information query and response respectively (not defined in
	// icmp6.h)
	case 139:						return 140;
	case 140:						return 139;

	// Home Agent Address Discovery Request Message and reply
	case 144:							return 145;
	case 145:							return 144;

	// TODO: Add further counterparts.

	default:			is_one_way = true; return icmp_code;
	}
	}

void ICMPSessionAdapter::AddExtraAnalyzers(Connection* conn)
	{
	static analyzer::Tag analyzer_connsize = analyzer_mgr->GetComponentTag("CONNSIZE");

	if ( analyzer_mgr->IsEnabled(analyzer_connsize) )
		// Add ConnSize analyzer. Needs to see packets, not stream.
		AddChildAnalyzer(new analyzer::conn_size::ConnSize_Analyzer(conn));
	}

void ICMPSessionAdapter::UpdateConnVal(zeek::RecordVal* conn_val)
	{
	const auto& orig_endp = conn_val->GetField("orig");
	const auto& resp_endp = conn_val->GetField("resp");

	UpdateEndpointVal(orig_endp, true);
	UpdateEndpointVal(resp_endp, false);

	analyzer::Analyzer::UpdateConnVal(conn_val);
	}

void ICMPSessionAdapter::UpdateEndpointVal(const ValPtr& endp_arg, bool is_orig)
	{
	Conn()->EnableStatusUpdateTimer();

	int size = is_orig ? request_len : reply_len;
	auto endp = endp_arg->AsRecordVal();

	if ( size < 0 )
		{
		endp->Assign(0, val_mgr->Count(0));
		endp->Assign(1, val_mgr->Count(int(ICMP_INACTIVE)));
		}
	else
		{
		endp->Assign(0, val_mgr->Count(size));
		endp->Assign(1, val_mgr->Count(int(ICMP_ACTIVE)));
		}
	}

void ICMPSessionAdapter::UpdateLength(bool is_orig, int len)
	{
	int& len_stat = is_orig ? request_len : reply_len;
	if ( len_stat < 0 )
		len_stat = len;
	else
		len_stat += len;
	}

void ICMPSessionAdapter::InitEndpointMatcher(const IP_Hdr* ip_hdr, int len, bool is_orig)
	{
	if ( zeek::detail::rule_matcher )
		{
		if ( ! matcher_state.MatcherInitialized(is_orig) )
			matcher_state.InitEndpointMatcher(this, ip_hdr, len, is_orig, nullptr);
		}
	}

void ICMPSessionAdapter::MatchEndpoint(const u_char* data, int len, bool is_orig)
	{
	if ( zeek::detail::rule_matcher )
		matcher_state.Match(zeek::detail::Rule::PAYLOAD, data, len, is_orig,
		                    false, false, true);
	}

void ICMPSessionAdapter::Done()
	{
	SessionAdapter::Done();
	matcher_state.FinishEndpointMatcher();
	}