github.com/humaniq/go-ethereum@v1.6.8-0.20171225131628-061223a13848/p2p/discv5/udp_test.go (about)

     1  // Copyright 2016 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package discv5
    18  
    19  import (
    20  	"encoding/hex"
    21  	"errors"
    22  	"io"
    23  	"net"
    24  	"reflect"
    25  	"sync"
    26  	"testing"
    27  	"time"
    28  
    29  	"github.com/davecgh/go-spew/spew"
    30  	"github.com/ethereum/go-ethereum/common"
    31  	"github.com/ethereum/go-ethereum/crypto"
    32  	"github.com/ethereum/go-ethereum/rlp"
    33  )
    34  
    35  func init() {
    36  	spew.Config.DisableMethods = true
    37  }
    38  
    39  // shared test variables
    40  var (
    41  	futureExp          = uint64(time.Now().Add(10 * time.Hour).Unix())
    42  	testTarget         = NodeID{0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1}
    43  	testRemote         = rpcEndpoint{IP: net.ParseIP("1.1.1.1").To4(), UDP: 1, TCP: 2}
    44  	testLocalAnnounced = rpcEndpoint{IP: net.ParseIP("2.2.2.2").To4(), UDP: 3, TCP: 4}
    45  	testLocal          = rpcEndpoint{IP: net.ParseIP("3.3.3.3").To4(), UDP: 5, TCP: 6}
    46  )
    47  
    48  // type udpTest struct {
    49  // 	t                   *testing.T
    50  // 	pipe                *dgramPipe
    51  // 	table               *Table
    52  // 	udp                 *udp
    53  // 	sent                [][]byte
    54  // 	localkey, remotekey *ecdsa.PrivateKey
    55  // 	remoteaddr          *net.UDPAddr
    56  // }
    57  //
    58  // func newUDPTest(t *testing.T) *udpTest {
    59  // 	test := &udpTest{
    60  // 		t:          t,
    61  // 		pipe:       newpipe(),
    62  // 		localkey:   newkey(),
    63  // 		remotekey:  newkey(),
    64  // 		remoteaddr: &net.UDPAddr{IP: net.IP{1, 2, 3, 4}, Port: 30303},
    65  // 	}
    66  // 	test.table, test.udp, _ = newUDP(test.localkey, test.pipe, nil, "")
    67  // 	return test
    68  // }
    69  //
    70  // // handles a packet as if it had been sent to the transport.
    71  // func (test *udpTest) packetIn(wantError error, ptype byte, data packet) error {
    72  // 	enc, err := encodePacket(test.remotekey, ptype, data)
    73  // 	if err != nil {
    74  // 		return test.errorf("packet (%d) encode error: %v", ptype, err)
    75  // 	}
    76  // 	test.sent = append(test.sent, enc)
    77  // 	if err = test.udp.handlePacket(test.remoteaddr, enc); err != wantError {
    78  // 		return test.errorf("error mismatch: got %q, want %q", err, wantError)
    79  // 	}
    80  // 	return nil
    81  // }
    82  //
    83  // // waits for a packet to be sent by the transport.
    84  // // validate should have type func(*udpTest, X) error, where X is a packet type.
    85  // func (test *udpTest) waitPacketOut(validate interface{}) error {
    86  // 	dgram := test.pipe.waitPacketOut()
    87  // 	p, _, _, err := decodePacket(dgram)
    88  // 	if err != nil {
    89  // 		return test.errorf("sent packet decode error: %v", err)
    90  // 	}
    91  // 	fn := reflect.ValueOf(validate)
    92  // 	exptype := fn.Type().In(0)
    93  // 	if reflect.TypeOf(p) != exptype {
    94  // 		return test.errorf("sent packet type mismatch, got: %v, want: %v", reflect.TypeOf(p), exptype)
    95  // 	}
    96  // 	fn.Call([]reflect.Value{reflect.ValueOf(p)})
    97  // 	return nil
    98  // }
    99  //
   100  // func (test *udpTest) errorf(format string, args ...interface{}) error {
   101  // 	_, file, line, ok := runtime.Caller(2) // errorf + waitPacketOut
   102  // 	if ok {
   103  // 		file = filepath.Base(file)
   104  // 	} else {
   105  // 		file = "???"
   106  // 		line = 1
   107  // 	}
   108  // 	err := fmt.Errorf(format, args...)
   109  // 	fmt.Printf("\t%s:%d: %v\n", file, line, err)
   110  // 	test.t.Fail()
   111  // 	return err
   112  // }
   113  //
   114  // func TestUDP_packetErrors(t *testing.T) {
   115  // 	test := newUDPTest(t)
   116  // 	defer test.table.Close()
   117  //
   118  // 	test.packetIn(errExpired, pingPacket, &ping{From: testRemote, To: testLocalAnnounced, Version: Version})
   119  // 	test.packetIn(errUnsolicitedReply, pongPacket, &pong{ReplyTok: []byte{}, Expiration: futureExp})
   120  // 	test.packetIn(errUnknownNode, findnodePacket, &findnode{Expiration: futureExp})
   121  // 	test.packetIn(errUnsolicitedReply, neighborsPacket, &neighbors{Expiration: futureExp})
   122  // }
   123  //
   124  // func TestUDP_findnode(t *testing.T) {
   125  // 	test := newUDPTest(t)
   126  // 	defer test.table.Close()
   127  //
   128  // 	// put a few nodes into the table. their exact
   129  // 	// distribution shouldn't matter much, although we need to
   130  // 	// take care not to overflow any bucket.
   131  // 	targetHash := crypto.Keccak256Hash(testTarget[:])
   132  // 	nodes := &nodesByDistance{target: targetHash}
   133  // 	for i := 0; i < bucketSize; i++ {
   134  // 		nodes.push(nodeAtDistance(test.table.self.sha, i+2), bucketSize)
   135  // 	}
   136  // 	test.table.stuff(nodes.entries)
   137  //
   138  // 	// ensure there's a bond with the test node,
   139  // 	// findnode won't be accepted otherwise.
   140  // 	test.table.db.updateNode(NewNode(
   141  // 		PubkeyID(&test.remotekey.PublicKey),
   142  // 		test.remoteaddr.IP,
   143  // 		uint16(test.remoteaddr.Port),
   144  // 		99,
   145  // 	))
   146  // 	// check that closest neighbors are returned.
   147  // 	test.packetIn(nil, findnodePacket, &findnode{Target: testTarget, Expiration: futureExp})
   148  // 	expected := test.table.closest(targetHash, bucketSize)
   149  //
   150  // 	waitNeighbors := func(want []*Node) {
   151  // 		test.waitPacketOut(func(p *neighbors) {
   152  // 			if len(p.Nodes) != len(want) {
   153  // 				t.Errorf("wrong number of results: got %d, want %d", len(p.Nodes), bucketSize)
   154  // 			}
   155  // 			for i := range p.Nodes {
   156  // 				if p.Nodes[i].ID != want[i].ID {
   157  // 					t.Errorf("result mismatch at %d:\n  got:  %v\n  want: %v", i, p.Nodes[i], expected.entries[i])
   158  // 				}
   159  // 			}
   160  // 		})
   161  // 	}
   162  // 	waitNeighbors(expected.entries[:maxNeighbors])
   163  // 	waitNeighbors(expected.entries[maxNeighbors:])
   164  // }
   165  //
   166  // func TestUDP_findnodeMultiReply(t *testing.T) {
   167  // 	test := newUDPTest(t)
   168  // 	defer test.table.Close()
   169  //
   170  // 	// queue a pending findnode request
   171  // 	resultc, errc := make(chan []*Node), make(chan error)
   172  // 	go func() {
   173  // 		rid := PubkeyID(&test.remotekey.PublicKey)
   174  // 		ns, err := test.udp.findnode(rid, test.remoteaddr, testTarget)
   175  // 		if err != nil && len(ns) == 0 {
   176  // 			errc <- err
   177  // 		} else {
   178  // 			resultc <- ns
   179  // 		}
   180  // 	}()
   181  //
   182  // 	// wait for the findnode to be sent.
   183  // 	// after it is sent, the transport is waiting for a reply
   184  // 	test.waitPacketOut(func(p *findnode) {
   185  // 		if p.Target != testTarget {
   186  // 			t.Errorf("wrong target: got %v, want %v", p.Target, testTarget)
   187  // 		}
   188  // 	})
   189  //
   190  // 	// send the reply as two packets.
   191  // 	list := []*Node{
   192  // 		MustParseNode("enode://ba85011c70bcc5c04d8607d3a0ed29aa6179c092cbdda10d5d32684fb33ed01bd94f588ca8f91ac48318087dcb02eaf36773a7a453f0eedd6742af668097b29c@10.0.1.16:30303?discport=30304"),
   193  // 		MustParseNode("enode://81fa361d25f157cd421c60dcc28d8dac5ef6a89476633339c5df30287474520caca09627da18543d9079b5b288698b542d56167aa5c09111e55acdbbdf2ef799@10.0.1.16:30303"),
   194  // 		MustParseNode("enode://9bffefd833d53fac8e652415f4973bee289e8b1a5c6c4cbe70abf817ce8a64cee11b823b66a987f51aaa9fba0d6a91b3e6bf0d5a5d1042de8e9eeea057b217f8@10.0.1.36:30301?discport=17"),
   195  // 		MustParseNode("enode://1b5b4aa662d7cb44a7221bfba67302590b643028197a7d5214790f3bac7aaa4a3241be9e83c09cf1f6c69d007c634faae3dc1b1221793e8446c0b3a09de65960@10.0.1.16:30303"),
   196  // 	}
   197  // 	rpclist := make([]rpcNode, len(list))
   198  // 	for i := range list {
   199  // 		rpclist[i] = nodeToRPC(list[i])
   200  // 	}
   201  // 	test.packetIn(nil, neighborsPacket, &neighbors{Expiration: futureExp, Nodes: rpclist[:2]})
   202  // 	test.packetIn(nil, neighborsPacket, &neighbors{Expiration: futureExp, Nodes: rpclist[2:]})
   203  //
   204  // 	// check that the sent neighbors are all returned by findnode
   205  // 	select {
   206  // 	case result := <-resultc:
   207  // 		if !reflect.DeepEqual(result, list) {
   208  // 			t.Errorf("neighbors mismatch:\n  got:  %v\n  want: %v", result, list)
   209  // 		}
   210  // 	case err := <-errc:
   211  // 		t.Errorf("findnode error: %v", err)
   212  // 	case <-time.After(5 * time.Second):
   213  // 		t.Error("findnode did not return within 5 seconds")
   214  // 	}
   215  // }
   216  //
   217  // func TestUDP_successfulPing(t *testing.T) {
   218  // 	test := newUDPTest(t)
   219  // 	added := make(chan *Node, 1)
   220  // 	test.table.nodeAddedHook = func(n *Node) { added <- n }
   221  // 	defer test.table.Close()
   222  //
   223  // 	// The remote side sends a ping packet to initiate the exchange.
   224  // 	go test.packetIn(nil, pingPacket, &ping{From: testRemote, To: testLocalAnnounced, Version: Version, Expiration: futureExp})
   225  //
   226  // 	// the ping is replied to.
   227  // 	test.waitPacketOut(func(p *pong) {
   228  // 		pinghash := test.sent[0][:macSize]
   229  // 		if !bytes.Equal(p.ReplyTok, pinghash) {
   230  // 			t.Errorf("got pong.ReplyTok %x, want %x", p.ReplyTok, pinghash)
   231  // 		}
   232  // 		wantTo := rpcEndpoint{
   233  // 			// The mirrored UDP address is the UDP packet sender
   234  // 			IP: test.remoteaddr.IP, UDP: uint16(test.remoteaddr.Port),
   235  // 			// The mirrored TCP port is the one from the ping packet
   236  // 			TCP: testRemote.TCP,
   237  // 		}
   238  // 		if !reflect.DeepEqual(p.To, wantTo) {
   239  // 			t.Errorf("got pong.To %v, want %v", p.To, wantTo)
   240  // 		}
   241  // 	})
   242  //
   243  // 	// remote is unknown, the table pings back.
   244  // 	test.waitPacketOut(func(p *ping) error {
   245  // 		if !reflect.DeepEqual(p.From, test.udp.ourEndpoint) {
   246  // 			t.Errorf("got ping.From %v, want %v", p.From, test.udp.ourEndpoint)
   247  // 		}
   248  // 		wantTo := rpcEndpoint{
   249  // 			// The mirrored UDP address is the UDP packet sender.
   250  // 			IP: test.remoteaddr.IP, UDP: uint16(test.remoteaddr.Port),
   251  // 			TCP: 0,
   252  // 		}
   253  // 		if !reflect.DeepEqual(p.To, wantTo) {
   254  // 			t.Errorf("got ping.To %v, want %v", p.To, wantTo)
   255  // 		}
   256  // 		return nil
   257  // 	})
   258  // 	test.packetIn(nil, pongPacket, &pong{Expiration: futureExp})
   259  //
   260  // 	// the node should be added to the table shortly after getting the
   261  // 	// pong packet.
   262  // 	select {
   263  // 	case n := <-added:
   264  // 		rid := PubkeyID(&test.remotekey.PublicKey)
   265  // 		if n.ID != rid {
   266  // 			t.Errorf("node has wrong ID: got %v, want %v", n.ID, rid)
   267  // 		}
   268  // 		if !bytes.Equal(n.IP, test.remoteaddr.IP) {
   269  // 			t.Errorf("node has wrong IP: got %v, want: %v", n.IP, test.remoteaddr.IP)
   270  // 		}
   271  // 		if int(n.UDP) != test.remoteaddr.Port {
   272  // 			t.Errorf("node has wrong UDP port: got %v, want: %v", n.UDP, test.remoteaddr.Port)
   273  // 		}
   274  // 		if n.TCP != testRemote.TCP {
   275  // 			t.Errorf("node has wrong TCP port: got %v, want: %v", n.TCP, testRemote.TCP)
   276  // 		}
   277  // 	case <-time.After(2 * time.Second):
   278  // 		t.Errorf("node was not added within 2 seconds")
   279  // 	}
   280  // }
   281  
   282  var testPackets = []struct {
   283  	input      string
   284  	wantPacket interface{}
   285  }{
   286  	{
   287  		input: "71dbda3a79554728d4f94411e42ee1f8b0d561c10e1e5f5893367948c6a7d70bb87b235fa28a77070271b6c164a2dce8c7e13a5739b53b5e96f2e5acb0e458a02902f5965d55ecbeb2ebb6cabb8b2b232896a36b737666c55265ad0a68412f250001ea04cb847f000001820cfa8215a8d790000000000000000000000000000000018208ae820d058443b9a355",
   288  		wantPacket: &ping{
   289  			Version:    4,
   290  			From:       rpcEndpoint{net.ParseIP("127.0.0.1").To4(), 3322, 5544},
   291  			To:         rpcEndpoint{net.ParseIP("::1"), 2222, 3333},
   292  			Expiration: 1136239445,
   293  			Rest:       []rlp.RawValue{},
   294  		},
   295  	},
   296  	{
   297  		input: "e9614ccfd9fc3e74360018522d30e1419a143407ffcce748de3e22116b7e8dc92ff74788c0b6663aaa3d67d641936511c8f8d6ad8698b820a7cf9e1be7155e9a241f556658c55428ec0563514365799a4be2be5a685a80971ddcfa80cb422cdd0101ec04cb847f000001820cfa8215a8d790000000000000000000000000000000018208ae820d058443b9a3550102",
   298  		wantPacket: &ping{
   299  			Version:    4,
   300  			From:       rpcEndpoint{net.ParseIP("127.0.0.1").To4(), 3322, 5544},
   301  			To:         rpcEndpoint{net.ParseIP("::1"), 2222, 3333},
   302  			Expiration: 1136239445,
   303  			Rest:       []rlp.RawValue{{0x01}, {0x02}},
   304  		},
   305  	},
   306  	{
   307  		input: "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",
   308  		wantPacket: &ping{
   309  			Version:    555,
   310  			From:       rpcEndpoint{net.ParseIP("2001:db8:3c4d:15::abcd:ef12"), 3322, 5544},
   311  			To:         rpcEndpoint{net.ParseIP("2001:db8:85a3:8d3:1319:8a2e:370:7348"), 2222, 33338},
   312  			Expiration: 1136239445,
   313  			Rest:       []rlp.RawValue{{0xC5, 0x01, 0x02, 0x03, 0x04, 0x05}},
   314  		},
   315  	},
   316  	{
   317  		input: "09b2428d83348d27cdf7064ad9024f526cebc19e4958f0fdad87c15eb598dd61d08423e0bf66b2069869e1724125f820d851c136684082774f870e614d95a2855d000f05d1648b2d5945470bc187c2d2216fbe870f43ed0909009882e176a46b0102f846d79020010db885a308d313198a2e037073488208ae82823aa0fbc914b16819237dcd8801d7e53f69e9719adecb3cc0e790c57e91ca4461c9548443b9a355c6010203c2040506a0c969a58f6f9095004c0177a6b47f451530cab38966a25cca5cb58f055542124e",
   318  		wantPacket: &pong{
   319  			To:         rpcEndpoint{net.ParseIP("2001:db8:85a3:8d3:1319:8a2e:370:7348"), 2222, 33338},
   320  			ReplyTok:   common.Hex2Bytes("fbc914b16819237dcd8801d7e53f69e9719adecb3cc0e790c57e91ca4461c954"),
   321  			Expiration: 1136239445,
   322  			Rest:       []rlp.RawValue{{0xC6, 0x01, 0x02, 0x03, 0xC2, 0x04, 0x05}, {0x06}},
   323  		},
   324  	},
   325  	{
   326  		input: "c7c44041b9f7c7e41934417ebac9a8e1a4c6298f74553f2fcfdcae6ed6fe53163eb3d2b52e39fe91831b8a927bf4fc222c3902202027e5e9eb812195f95d20061ef5cd31d502e47ecb61183f74a504fe04c51e73df81f25c4d506b26db4517490103f84eb840ca634cae0d49acb401d8a4c6b6fe8c55b70d115bf400769cc1400f3258cd31387574077f301b421bc84df7266c44e9e6d569fc56be00812904767bf5ccd1fc7f8443b9a35582999983999999280dc62cc8255c73471e0a61da0c89acdc0e035e260add7fc0c04ad9ebf3919644c91cb247affc82b69bd2ca235c71eab8e49737c937a2c396",
   327  		wantPacket: &findnode{
   328  			Target:     MustHexID("ca634cae0d49acb401d8a4c6b6fe8c55b70d115bf400769cc1400f3258cd31387574077f301b421bc84df7266c44e9e6d569fc56be00812904767bf5ccd1fc7f"),
   329  			Expiration: 1136239445,
   330  			Rest:       []rlp.RawValue{{0x82, 0x99, 0x99}, {0x83, 0x99, 0x99, 0x99}},
   331  		},
   332  	},
   333  	{
   334  		input: "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",
   335  		wantPacket: &neighbors{
   336  			Nodes: []rpcNode{
   337  				{
   338  					ID:  MustHexID("3155e1427f85f10a5c9a7755877748041af1bcd8d474ec065eb33df57a97babf54bfd2103575fa829115d224c523596b401065a97f74010610fce76382c0bf32"),
   339  					IP:  net.ParseIP("99.33.22.55").To4(),
   340  					UDP: 4444,
   341  					TCP: 4445,
   342  				},
   343  				{
   344  					ID:  MustHexID("312c55512422cf9b8a4097e9a6ad79402e87a15ae909a4bfefa22398f03d20951933beea1e4dfa6f968212385e829f04c2d314fc2d4e255e0d3bc08792b069db"),
   345  					IP:  net.ParseIP("1.2.3.4").To4(),
   346  					UDP: 1,
   347  					TCP: 1,
   348  				},
   349  				{
   350  					ID:  MustHexID("38643200b172dcfef857492156971f0e6aa2c538d8b74010f8e140811d53b98c765dd2d96126051913f44582e8c199ad7c6d6819e9a56483f637feaac9448aac"),
   351  					IP:  net.ParseIP("2001:db8:3c4d:15::abcd:ef12"),
   352  					UDP: 3333,
   353  					TCP: 3333,
   354  				},
   355  				{
   356  					ID:  MustHexID("8dcab8618c3253b558d459da53bd8fa68935a719aff8b811197101a4b2b47dd2d47295286fc00cc081bb542d760717d1bdd6bec2c37cd72eca367d6dd3b9df73"),
   357  					IP:  net.ParseIP("2001:db8:85a3:8d3:1319:8a2e:370:7348"),
   358  					UDP: 999,
   359  					TCP: 1000,
   360  				},
   361  			},
   362  			Expiration: 1136239445,
   363  			Rest:       []rlp.RawValue{{0x01}, {0x02}, {0x03}},
   364  		},
   365  	},
   366  }
   367  
   368  func TestForwardCompatibility(t *testing.T) {
   369  	t.Skip("skipped while working on discovery v5")
   370  
   371  	testkey, _ := crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
   372  	wantNodeID := PubkeyID(&testkey.PublicKey)
   373  
   374  	for _, test := range testPackets {
   375  		input, err := hex.DecodeString(test.input)
   376  		if err != nil {
   377  			t.Fatalf("invalid hex: %s", test.input)
   378  		}
   379  		var pkt ingressPacket
   380  		if err := decodePacket(input, &pkt); err != nil {
   381  			t.Errorf("did not accept packet %s\n%v", test.input, err)
   382  			continue
   383  		}
   384  		if !reflect.DeepEqual(pkt.data, test.wantPacket) {
   385  			t.Errorf("got %s\nwant %s", spew.Sdump(pkt.data), spew.Sdump(test.wantPacket))
   386  		}
   387  		if pkt.remoteID != wantNodeID {
   388  			t.Errorf("got id %v\nwant id %v", pkt.remoteID, wantNodeID)
   389  		}
   390  	}
   391  }
   392  
   393  // dgramPipe is a fake UDP socket. It queues all sent datagrams.
   394  type dgramPipe struct {
   395  	mu      *sync.Mutex
   396  	cond    *sync.Cond
   397  	closing chan struct{}
   398  	closed  bool
   399  	queue   [][]byte
   400  }
   401  
   402  func newpipe() *dgramPipe {
   403  	mu := new(sync.Mutex)
   404  	return &dgramPipe{
   405  		closing: make(chan struct{}),
   406  		cond:    &sync.Cond{L: mu},
   407  		mu:      mu,
   408  	}
   409  }
   410  
   411  // WriteToUDP queues a datagram.
   412  func (c *dgramPipe) WriteToUDP(b []byte, to *net.UDPAddr) (n int, err error) {
   413  	msg := make([]byte, len(b))
   414  	copy(msg, b)
   415  	c.mu.Lock()
   416  	defer c.mu.Unlock()
   417  	if c.closed {
   418  		return 0, errors.New("closed")
   419  	}
   420  	c.queue = append(c.queue, msg)
   421  	c.cond.Signal()
   422  	return len(b), nil
   423  }
   424  
   425  // ReadFromUDP just hangs until the pipe is closed.
   426  func (c *dgramPipe) ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error) {
   427  	<-c.closing
   428  	return 0, nil, io.EOF
   429  }
   430  
   431  func (c *dgramPipe) Close() error {
   432  	c.mu.Lock()
   433  	defer c.mu.Unlock()
   434  	if !c.closed {
   435  		close(c.closing)
   436  		c.closed = true
   437  	}
   438  	return nil
   439  }
   440  
   441  func (c *dgramPipe) LocalAddr() net.Addr {
   442  	return &net.UDPAddr{IP: testLocal.IP, Port: int(testLocal.UDP)}
   443  }
   444  
   445  func (c *dgramPipe) waitPacketOut() []byte {
   446  	c.mu.Lock()
   447  	defer c.mu.Unlock()
   448  	for len(c.queue) == 0 {
   449  		c.cond.Wait()
   450  	}
   451  	p := c.queue[0]
   452  	copy(c.queue, c.queue[1:])
   453  	c.queue = c.queue[:len(c.queue)-1]
   454  	return p
   455  }