mirror of
https://github.com/slackhq/nebula.git
synced 2026-07-01 02:50:29 +02:00
add IPv6 reject packet generation (#1766)
* add IPv6 reject packet generation (ICMPv6 Destination Unreachable and TCP RST) * use ICMPv6 code 1 (administratively prohibited) and cap body at 1000 bytes * cleanup, use ICMP error code 13 for ipv4 * better docs * cleanup
This commit is contained in:
Wade Simmons
+169
-1
@@ -1,11 +1,13 @@
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package iputil
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import (
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"encoding/binary"
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"net"
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"testing"
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"github.com/stretchr/testify/assert"
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"golang.org/x/net/ipv4"
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"golang.org/x/net/ipv6"
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)
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func Test_CreateRejectPacket(t *testing.T) {
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@@ -43,7 +45,7 @@ func Test_CreateRejectPacket(t *testing.T) {
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}
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b = append(b, []byte{0, 3, 0, 4, 0, 0, 0, 0}...)
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expectedLen = MaxRejectPacketSize
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expectedLen = maxIPv4RejectPacketSize
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out = make([]byte, MaxRejectPacketSize)
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rejectPacket = CreateRejectPacket(b, out)
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assert.NotNil(t, rejectPacket)
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@@ -71,3 +73,169 @@ func Test_CreateRejectPacket(t *testing.T) {
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assert.NotNil(t, rejectPacket)
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assert.Len(t, rejectPacket, expectedLen)
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}
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func makeIPv6Packet(src, dst net.IP, nextHeader uint8, payload []byte) []byte {
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b := make([]byte, ipv6.HeaderLen+len(payload))
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b[0] = ipv6.Version << 4
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binary.BigEndian.PutUint16(b[4:], uint16(len(payload)))
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b[6] = nextHeader
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b[7] = 64
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copy(b[8:24], src.To16())
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copy(b[24:40], dst.To16())
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copy(b[ipv6.HeaderLen:], payload)
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return b
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}
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func Test_CreateRejectPacketIPv6_ICMP(t *testing.T) {
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src := net.ParseIP("fd00::1")
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dst := net.ParseIP("fd00::2")
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// Small UDP packet: entire original included in body
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udpPayload := make([]byte, 20)
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udpPayload[0] = 0x00 // src port high
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udpPayload[1] = 0x50 // src port low (80)
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udpPayload[2] = 0x01 // dst port high
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udpPayload[3] = 0xBB // dst port low (443)
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packet := makeIPv6Packet(src, dst, 17, udpPayload)
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out := make([]byte, MaxRejectPacketSize)
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rejectPacket := CreateRejectPacket(packet, out)
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assert.NotNil(t, rejectPacket)
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// Small packet fits entirely: 40 (ipv6 hdr) + 8 (icmpv6 hdr) + 60 (original)
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expectedLen := ipv6.HeaderLen + 8 + len(packet)
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assert.Len(t, rejectPacket, expectedLen)
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// Verify version
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assert.Equal(t, byte(ipv6.Version<<4), rejectPacket[0]&0xf0)
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// Verify next header is ICMPv6 (58)
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assert.Equal(t, byte(58), rejectPacket[6])
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// Verify src/dst are swapped
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assert.Equal(t, dst.To16(), net.IP(rejectPacket[8:24]))
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assert.Equal(t, src.To16(), net.IP(rejectPacket[24:40]))
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// Verify ICMPv6 type=1 (Dest Unreachable), code=1 (Administratively prohibited)
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assert.Equal(t, byte(1), rejectPacket[ipv6.HeaderLen])
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assert.Equal(t, byte(1), rejectPacket[ipv6.HeaderLen+1])
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// Verify entire original packet is included in body
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assert.Equal(t, packet, rejectPacket[ipv6.HeaderLen+8:])
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// Large packet: body is truncated to 1000 bytes
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largePkt := makeIPv6Packet(src, dst, 17, make([]byte, 1200))
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rejectPacket = CreateRejectPacket(largePkt, out)
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assert.NotNil(t, rejectPacket)
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assert.Len(t, rejectPacket, ipv6.HeaderLen+8+1000)
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assert.Equal(t, largePkt[:1000], rejectPacket[ipv6.HeaderLen+8:])
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}
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func Test_CreateRejectPacketIPv6_TCP(t *testing.T) {
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src := net.ParseIP("fd00::1")
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dst := net.ParseIP("fd00::2")
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// TCP SYN packet (next header 6)
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tcpPayload := make([]byte, 20)
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tcpPayload[0] = 0x00 // src port high
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tcpPayload[1] = 0x50 // src port low (80)
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tcpPayload[2] = 0x01 // dst port high
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tcpPayload[3] = 0xBB // dst port low (443)
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binary.BigEndian.PutUint32(tcpPayload[4:], 1000) // seq
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binary.BigEndian.PutUint32(tcpPayload[8:], 0) // ack seq
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tcpPayload[12] = (20 >> 2) << 4 // data offset
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tcpPayload[13] = 0b00000010 // SYN flag
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packet := makeIPv6Packet(src, dst, 6, tcpPayload)
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out := make([]byte, MaxRejectPacketSize)
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rejectPacket := CreateRejectPacket(packet, out)
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assert.NotNil(t, rejectPacket)
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// Expected: 40 (ipv6 hdr) + 20 (tcp RST)
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expectedLen := ipv6.HeaderLen + 20
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assert.Len(t, rejectPacket, expectedLen)
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// Verify version
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assert.Equal(t, byte(ipv6.Version<<4), rejectPacket[0]&0xf0)
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// Verify next header is TCP (6)
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assert.Equal(t, byte(6), rejectPacket[6])
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// Verify src/dst are swapped
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assert.Equal(t, dst.To16(), net.IP(rejectPacket[8:24]))
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assert.Equal(t, src.To16(), net.IP(rejectPacket[24:40]))
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// Verify ports are swapped
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tcpOut := rejectPacket[ipv6.HeaderLen:]
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assert.Equal(t, uint16(443), binary.BigEndian.Uint16(tcpOut[0:2]))
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assert.Equal(t, uint16(80), binary.BigEndian.Uint16(tcpOut[2:4]))
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// RST+ACK flags (since input was SYN without ACK)
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assert.Equal(t, byte(0b00010100), tcpOut[13])
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// ack_seq = original seq (1000) + SYN (1) + FIN (0) + segment data (0)
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assert.Equal(t, uint32(1001), binary.BigEndian.Uint32(tcpOut[8:]))
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}
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func Test_CreateRejectPacketIPv6_TCPWithACK(t *testing.T) {
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src := net.ParseIP("fd00::1")
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dst := net.ParseIP("fd00::2")
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// TCP packet with ACK set
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tcpPayload := make([]byte, 20)
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tcpPayload[0] = 0x00
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tcpPayload[1] = 0x50
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tcpPayload[2] = 0x01
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tcpPayload[3] = 0xBB
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binary.BigEndian.PutUint32(tcpPayload[4:], 1000) // seq
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binary.BigEndian.PutUint32(tcpPayload[8:], 2000) // ack seq
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tcpPayload[12] = (20 >> 2) << 4 // data offset
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tcpPayload[13] = 0b00010000 // ACK flag
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packet := makeIPv6Packet(src, dst, 6, tcpPayload)
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out := make([]byte, MaxRejectPacketSize)
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rejectPacket := CreateRejectPacket(packet, out)
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assert.NotNil(t, rejectPacket)
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tcpOut := rejectPacket[ipv6.HeaderLen:]
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// RST only (no ACK) since input had ACK
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assert.Equal(t, byte(0b00000100), tcpOut[13])
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// seq = original ack_seq
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assert.Equal(t, uint32(2000), binary.BigEndian.Uint32(tcpOut[4:]))
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}
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func Test_CreateRejectPacketIPv6_TooShort(t *testing.T) {
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// Packet too short to be valid IPv6
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out := make([]byte, MaxRejectPacketSize)
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assert.Nil(t, CreateRejectPacket([]byte{0x60}, out))
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assert.Nil(t, CreateRejectPacket(make([]byte, 39), out))
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}
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func Test_CreateRejectPacketIPv6_ExtensionHeaders(t *testing.T) {
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src := net.ParseIP("fd00::1")
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dst := net.ParseIP("fd00::2")
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// IPv6 + Hop-by-Hop extension header + TCP
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hopByHop := []byte{
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6, // next header: TCP
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0, // length (8 bytes total)
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0, 0, // padding
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0, 0, 0, 0,
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}
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tcpPayload := make([]byte, 20)
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tcpPayload[0] = 0x00
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tcpPayload[1] = 0x50
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tcpPayload[2] = 0x01
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tcpPayload[3] = 0xBB
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binary.BigEndian.PutUint32(tcpPayload[4:], 1000)
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binary.BigEndian.PutUint32(tcpPayload[8:], 2000)
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tcpPayload[12] = (20 >> 2) << 4
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tcpPayload[13] = 0b00010000 // ACK
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payload := append(hopByHop, tcpPayload...)
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packet := makeIPv6Packet(src, dst, 0, payload) // next header 0 = Hop-by-Hop
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out := make([]byte, MaxRejectPacketSize)
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rejectPacket := CreateRejectPacket(packet, out)
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assert.NotNil(t, rejectPacket)
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// Should produce TCP RST
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expectedLen := ipv6.HeaderLen + 20
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assert.Len(t, rejectPacket, expectedLen)
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assert.Equal(t, byte(6), rejectPacket[6]) // next header is TCP
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tcpOut := rejectPacket[ipv6.HeaderLen:]
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assert.Equal(t, byte(0b00000100), tcpOut[13]) // RST only
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}
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