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407 lines
11 KiB
Go
407 lines
11 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package filter
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import (
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"encoding/binary"
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"encoding/hex"
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"encoding/json"
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"net"
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"strings"
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"testing"
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"tailscale.com/net/packet"
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"tailscale.com/types/logger"
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)
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var Unknown = packet.Unknown
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var ICMP = packet.ICMP
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var TCP = packet.TCP
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var UDP = packet.UDP
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var Fragment = packet.Fragment
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func nets(ips []packet.IP4) []Net {
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out := make([]Net, 0, len(ips))
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for _, ip := range ips {
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out = append(out, Net{ip, Netmask(32)})
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}
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return out
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}
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func ippr(ip packet.IP4, start, end uint16) []NetPortRange {
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return []NetPortRange{
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NetPortRange{Net{ip, Netmask(32)}, PortRange{start, end}},
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}
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}
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func netpr(ip packet.IP4, bits int, start, end uint16) []NetPortRange {
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return []NetPortRange{
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NetPortRange{Net{ip, Netmask(bits)}, PortRange{start, end}},
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}
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}
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var matches = Matches{
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{Srcs: nets([]packet.IP4{0x08010101, 0x08020202}), Dsts: []NetPortRange{
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NetPortRange{Net{0x01020304, Netmask(32)}, PortRange{22, 22}},
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NetPortRange{Net{0x05060708, Netmask(32)}, PortRange{23, 24}},
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}},
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{Srcs: nets([]packet.IP4{0x08010101, 0x08020202}), Dsts: ippr(0x05060708, 27, 28)},
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{Srcs: nets([]packet.IP4{0x02020202}), Dsts: ippr(0x08010101, 22, 22)},
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{Srcs: []Net{NetAny}, Dsts: ippr(0x647a6232, 0, 65535)},
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{Srcs: []Net{NetAny}, Dsts: netpr(0, 0, 443, 443)},
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{Srcs: nets([]packet.IP4{0x99010101, 0x99010102, 0x99030303}), Dsts: ippr(0x01020304, 999, 999)},
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}
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func newFilter(logf logger.Logf) *Filter {
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// Expects traffic to 100.122.98.50, 1.2.3.4, 5.6.7.8,
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// 102.102.102.102, 119.119.119.119, 8.1.0.0/16
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localNets := nets([]packet.IP4{0x647a6232, 0x01020304, 0x05060708, 0x66666666, 0x77777777})
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localNets = append(localNets, Net{packet.IP4(0x08010000), Netmask(16)})
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return New(matches, localNets, nil, logf)
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}
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func TestMarshal(t *testing.T) {
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for _, ent := range []Matches{Matches{matches[0]}, matches} {
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b, err := json.Marshal(ent)
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if err != nil {
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t.Fatalf("marshal: %v", err)
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}
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mm2 := Matches{}
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if err := json.Unmarshal(b, &mm2); err != nil {
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t.Fatalf("unmarshal: %v (%v)", err, string(b))
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}
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}
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}
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func TestFilter(t *testing.T) {
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acl := newFilter(t.Logf)
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// check packet filtering based on the table
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type InOut struct {
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want Response
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p packet.ParsedPacket
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}
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tests := []InOut{
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// Basic
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{Accept, parsed(TCP, 0x08010101, 0x01020304, 999, 22)},
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{Accept, parsed(UDP, 0x08010101, 0x01020304, 999, 22)},
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{Accept, parsed(ICMP, 0x08010101, 0x01020304, 0, 0)},
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{Drop, parsed(TCP, 0x08010101, 0x01020304, 0, 0)},
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{Accept, parsed(TCP, 0x08010101, 0x01020304, 0, 22)},
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{Drop, parsed(TCP, 0x08010101, 0x01020304, 0, 21)},
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{Accept, parsed(TCP, 0x11223344, 0x08012233, 0, 443)},
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{Drop, parsed(TCP, 0x11223344, 0x08012233, 0, 444)},
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{Accept, parsed(TCP, 0x11223344, 0x647a6232, 0, 999)},
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{Accept, parsed(TCP, 0x11223344, 0x647a6232, 0, 0)},
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// localNets prefilter - accepted by policy filter, but
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// unexpected dst IP.
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{Drop, parsed(TCP, 0x08010101, 0x10203040, 0, 443)},
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// Stateful UDP. Note each packet is run through the input
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// filter, then the output filter (which sets conntrack
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// state).
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// Initially empty cache
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{Drop, parsed(UDP, 0x77777777, 0x66666666, 4242, 4343)},
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// Return packet from previous attempt is allowed
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{Accept, parsed(UDP, 0x66666666, 0x77777777, 4343, 4242)},
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// Because of the return above, initial attempt is allowed now
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{Accept, parsed(UDP, 0x77777777, 0x66666666, 4242, 4343)},
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}
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for i, test := range tests {
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if got, _ := acl.runIn(&test.p); test.want != got {
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t.Errorf("#%d got=%v want=%v packet:%v\n", i, got, test.want, test.p)
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}
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// Update UDP state
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_, _ = acl.runOut(&test.p)
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}
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}
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func TestNoAllocs(t *testing.T) {
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acl := newFilter(t.Logf)
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tcpPacket := rawpacket(TCP, 0x08010101, 0x01020304, 999, 22, 0)
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udpPacket := rawpacket(UDP, 0x08010101, 0x01020304, 999, 22, 0)
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tests := []struct {
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name string
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in bool
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want int
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packet []byte
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}{
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{"tcp_in", true, 0, tcpPacket},
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{"tcp_out", false, 0, tcpPacket},
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{"udp_in", true, 0, udpPacket},
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// One alloc is inevitable (an lru cache update)
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{"udp_out", false, 1, udpPacket},
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}
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for _, test := range tests {
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t.Run(test.name, func(t *testing.T) {
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got := int(testing.AllocsPerRun(1000, func() {
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q := &packet.ParsedPacket{}
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q.Decode(test.packet)
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if test.in {
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acl.RunIn(q, 0)
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} else {
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acl.RunOut(q, 0)
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}
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}))
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if got > test.want {
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t.Errorf("got %d allocs per run; want at most %d", got, test.want)
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}
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})
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}
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}
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func TestParseIP(t *testing.T) {
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tests := []struct {
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host string
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bits int
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want Net
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wantErr string
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}{
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{"8.8.8.8", 24, Net{IP: packet.NewIP4(net.ParseIP("8.8.8.8")), Mask: packet.NewIP4(net.ParseIP("255.255.255.0"))}, ""},
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{"8.8.8.8", 33, Net{}, `invalid CIDR size 33 for host "8.8.8.8"`},
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{"8.8.8.8", -1, Net{}, `invalid CIDR size -1 for host "8.8.8.8"`},
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{"0.0.0.0", 24, Net{}, `ports="0.0.0.0": to allow all IP addresses, use *:port, not 0.0.0.0:port`},
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{"*", 24, NetAny, ""},
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{"fe80::1", 128, NetNone, `ports="fe80::1": invalid IPv4 address`},
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}
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for _, tt := range tests {
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got, err := parseIP(tt.host, tt.bits)
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if err != nil {
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if err.Error() == tt.wantErr {
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continue
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}
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t.Errorf("parseIP(%q, %v) error: %v; want error %q", tt.host, tt.bits, err, tt.wantErr)
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}
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if got != tt.want {
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t.Errorf("parseIP(%q, %v) = %#v; want %#v", tt.host, tt.bits, got, tt.want)
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continue
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}
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}
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}
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func BenchmarkFilter(b *testing.B) {
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acl := newFilter(b.Logf)
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tcpPacket := rawpacket(TCP, 0x08010101, 0x01020304, 999, 22, 0)
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udpPacket := rawpacket(UDP, 0x08010101, 0x01020304, 999, 22, 0)
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icmpPacket := rawpacket(ICMP, 0x08010101, 0x01020304, 0, 0, 0)
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tcpSynPacket := rawpacket(TCP, 0x08010101, 0x01020304, 999, 22, 0)
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// TCP filtering is trivial (Accept) for non-SYN packets.
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tcpSynPacket[33] = packet.TCPSyn
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benches := []struct {
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name string
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in bool
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packet []byte
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}{
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// Non-SYN TCP and ICMP have similar code paths in and out.
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{"icmp", true, icmpPacket},
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{"tcp", true, tcpPacket},
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{"tcp_syn_in", true, tcpSynPacket},
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{"tcp_syn_out", false, tcpSynPacket},
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{"udp_in", true, udpPacket},
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{"udp_out", false, udpPacket},
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}
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for _, bench := range benches {
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b.Run(bench.name, func(b *testing.B) {
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for i := 0; i < b.N; i++ {
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q := &packet.ParsedPacket{}
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q.Decode(bench.packet)
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// This branch seems to have no measurable impact on performance.
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if bench.in {
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acl.RunIn(q, 0)
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} else {
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acl.RunOut(q, 0)
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}
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}
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})
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}
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}
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func TestPreFilter(t *testing.T) {
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packets := []struct {
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desc string
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want Response
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b []byte
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}{
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{"empty", Accept, []byte{}},
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{"short", Drop, []byte("short")},
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{"junk", Drop, rawdefault(Unknown, 10)},
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{"fragment", Accept, rawdefault(Fragment, 40)},
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{"tcp", noVerdict, rawdefault(TCP, 200)},
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{"udp", noVerdict, rawdefault(UDP, 200)},
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{"icmp", noVerdict, rawdefault(ICMP, 200)},
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}
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f := NewAllowNone(t.Logf)
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for _, testPacket := range packets {
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p := &packet.ParsedPacket{}
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p.Decode(testPacket.b)
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got := f.pre(p, LogDrops|LogAccepts, in)
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if got != testPacket.want {
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t.Errorf("%q got=%v want=%v packet:\n%s", testPacket.desc, got, testPacket.want, packet.Hexdump(testPacket.b))
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}
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}
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}
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func parsed(proto packet.IP4Proto, src, dst packet.IP4, sport, dport uint16) packet.ParsedPacket {
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return packet.ParsedPacket{
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IPProto: proto,
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SrcIP: src,
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DstIP: dst,
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SrcPort: sport,
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DstPort: dport,
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TCPFlags: packet.TCPSyn,
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}
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}
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// rawpacket generates a packet with given source and destination ports and IPs
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// and resizes the header to trimLength if it is nonzero.
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func rawpacket(proto packet.IP4Proto, src, dst packet.IP4, sport, dport uint16, trimLength int) []byte {
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var headerLength int
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switch proto {
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case ICMP:
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headerLength = 24
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case TCP:
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headerLength = 40
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case UDP:
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headerLength = 28
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default:
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headerLength = 24
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}
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if trimLength > headerLength {
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headerLength = trimLength
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}
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if trimLength == 0 {
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trimLength = headerLength
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}
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bin := binary.BigEndian
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hdr := make([]byte, headerLength)
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hdr[0] = 0x45
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bin.PutUint16(hdr[2:4], uint16(trimLength))
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hdr[8] = 64
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bin.PutUint32(hdr[12:16], uint32(src))
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bin.PutUint32(hdr[16:20], uint32(dst))
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// ports
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bin.PutUint16(hdr[20:22], sport)
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bin.PutUint16(hdr[22:24], dport)
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switch proto {
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case ICMP:
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hdr[9] = 1
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case TCP:
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hdr[9] = 6
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case UDP:
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hdr[9] = 17
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case Fragment:
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hdr[9] = 6
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// flags + fragOff
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bin.PutUint16(hdr[6:8], (1<<13)|1234)
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case Unknown:
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default:
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panic("unknown protocol")
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}
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// Trim the header if requested
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hdr = hdr[:trimLength]
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return hdr
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}
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// rawdefault calls rawpacket with default ports and IPs.
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func rawdefault(proto packet.IP4Proto, trimLength int) []byte {
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ip := packet.IP4(0x08080808) // 8.8.8.8
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port := uint16(53)
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return rawpacket(proto, ip, ip, port, port, trimLength)
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}
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func parseHexPkt(t *testing.T, h string) *packet.ParsedPacket {
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t.Helper()
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b, err := hex.DecodeString(strings.ReplaceAll(h, " ", ""))
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if err != nil {
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t.Fatalf("failed to read hex %q: %v", h, err)
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}
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p := new(packet.ParsedPacket)
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p.Decode(b)
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return p
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}
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func TestOmitDropLogging(t *testing.T) {
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tests := []struct {
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name string
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pkt *packet.ParsedPacket
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dir direction
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want bool
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}{
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{
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name: "v4_tcp_out",
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pkt: &packet.ParsedPacket{IPVersion: 4, IPProto: packet.TCP},
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dir: out,
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want: false,
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},
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{
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name: "v6_icmp_out", // as seen on Linux
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pkt: parseHexPkt(t, "60 00 00 00 00 00 3a 00 fe800000000000000000000000000000 ff020000000000000000000000000002"),
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dir: out,
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want: true,
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},
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{
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name: "v6_to_MLDv2_capable_routers", // as seen on Windows
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pkt: parseHexPkt(t, "60 00 00 00 00 24 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff 02 00 00 00 00 00 00 00 00 00 00 00 00 00 16 3a 00 05 02 00 00 01 00 8f 00 6e 80 00 00 00 01 04 00 00 00 ff 02 00 00 00 00 00 00 00 00 00 00 00 00 00 0c"),
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dir: out,
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want: true,
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},
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{
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name: "v4_igmp_out", // on Windows, from https://github.com/tailscale/tailscale/issues/618
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pkt: parseHexPkt(t, "46 00 00 30 37 3a 00 00 01 02 10 0e a9 fe 53 6b e0 00 00 16 94 04 00 00 22 00 14 05 00 00 00 02 04 00 00 00 e0 00 00 fb 04 00 00 00 e0 00 00 fc"),
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dir: out,
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want: true,
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},
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{
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name: "v6_udp_multicast",
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pkt: parseHexPkt(t, "60 00 00 00 00 00 11 00 fe800000000000007dc6bc04499262a3 ff120000000000000000000000008384"),
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dir: out,
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want: true,
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},
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{
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name: "v4_multicast_out_low",
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pkt: &packet.ParsedPacket{IPVersion: 4, DstIP: packet.NewIP4(net.ParseIP("224.0.0.0"))},
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dir: out,
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want: true,
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},
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{
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name: "v4_multicast_out_high",
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pkt: &packet.ParsedPacket{IPVersion: 4, DstIP: packet.NewIP4(net.ParseIP("239.255.255.255"))},
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dir: out,
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want: true,
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},
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{
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name: "v4_link_local_unicast",
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pkt: &packet.ParsedPacket{IPVersion: 4, DstIP: packet.NewIP4(net.ParseIP("169.254.1.2"))},
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dir: out,
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want: true,
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got := omitDropLogging(tt.pkt, tt.dir)
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if got != tt.want {
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t.Errorf("got %v; want %v\npacket: %#v\n%s", got, tt.want, tt.pkt, packet.Hexdump(tt.pkt.Buffer()))
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}
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})
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}
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}
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