github.com/Bytom/bytom@v1.1.2-0.20210127130405-ae40204c0b09/p2p/discover/dht/node.go (about)

     1  package dht
     2  
     3  import (
     4  	"crypto/ecdsa"
     5  	"crypto/elliptic"
     6  	"encoding/hex"
     7  	"errors"
     8  	"fmt"
     9  	"math/rand"
    10  	"net"
    11  	"net/url"
    12  	"regexp"
    13  	"strconv"
    14  	"strings"
    15  	"time"
    16  
    17  	"github.com/bytom/bytom/common"
    18  	"github.com/bytom/bytom/crypto"
    19  )
    20  
    21  // Node represents a host on the network.
    22  // The public fields of Node may not be modified.
    23  type Node struct {
    24  	IP       net.IP // len 4 for IPv4 or 16 for IPv6
    25  	UDP, TCP uint16 // port numbers
    26  	ID       NodeID // the node's public key
    27  
    28  	// Network-related fields are contained in nodeNetGuts.
    29  	// These fields are not supposed to be used off the
    30  	// Network.loop goroutine.
    31  	nodeNetGuts
    32  }
    33  
    34  // NewNode creates a new node. It is mostly meant to be used for
    35  // testing purposes.
    36  func NewNode(id NodeID, ip net.IP, udpPort, tcpPort uint16) *Node {
    37  	if ipv4 := ip.To4(); ipv4 != nil {
    38  		ip = ipv4
    39  	}
    40  	return &Node{
    41  		IP:          ip,
    42  		UDP:         udpPort,
    43  		TCP:         tcpPort,
    44  		ID:          id,
    45  		nodeNetGuts: nodeNetGuts{sha: crypto.Sha256Hash(id[:])},
    46  	}
    47  }
    48  
    49  func (n *Node) addr() *net.UDPAddr {
    50  	return &net.UDPAddr{IP: n.IP, Port: int(n.UDP)}
    51  }
    52  
    53  func (n *Node) setAddr(a *net.UDPAddr) {
    54  	n.IP = a.IP
    55  	if ipv4 := a.IP.To4(); ipv4 != nil {
    56  		n.IP = ipv4
    57  	}
    58  	n.UDP = uint16(a.Port)
    59  }
    60  
    61  // compares the given address against the stored values.
    62  func (n *Node) addrEqual(a *net.UDPAddr) bool {
    63  	ip := a.IP
    64  	if ipv4 := a.IP.To4(); ipv4 != nil {
    65  		ip = ipv4
    66  	}
    67  	return n.UDP == uint16(a.Port) && n.IP.Equal(ip)
    68  }
    69  
    70  // Incomplete returns true for nodes with no IP address.
    71  func (n *Node) Incomplete() bool {
    72  	return n.IP == nil
    73  }
    74  
    75  // checks whether n is a valid complete node.
    76  func (n *Node) validateComplete() error {
    77  	if n.Incomplete() {
    78  		return errors.New("incomplete node")
    79  	}
    80  	if n.UDP == 0 {
    81  		return errors.New("missing UDP port")
    82  	}
    83  	if n.TCP == 0 {
    84  		return errors.New("missing TCP port")
    85  	}
    86  	if n.IP.IsMulticast() || n.IP.IsUnspecified() {
    87  		return errors.New("invalid IP (multicast/unspecified)")
    88  	}
    89  	//_, err := n.ID.Pubkey() // validate the key (on curve, etc.)
    90  	return nil
    91  }
    92  
    93  // The string representation of a Node is a URL.
    94  // Please see ParseNode for a description of the format.
    95  func (n *Node) String() string {
    96  	u := url.URL{Scheme: "enode"}
    97  	if n.Incomplete() {
    98  		u.Host = fmt.Sprintf("%x", n.ID[:])
    99  	} else {
   100  		addr := net.TCPAddr{IP: n.IP, Port: int(n.TCP)}
   101  		u.User = url.User(fmt.Sprintf("%x", n.ID[:]))
   102  		u.Host = addr.String()
   103  		if n.UDP != n.TCP {
   104  			u.RawQuery = "discport=" + strconv.Itoa(int(n.UDP))
   105  		}
   106  	}
   107  	return u.String()
   108  }
   109  
   110  var incompleteNodeURL = regexp.MustCompile("(?i)^(?:enode://)?([0-9a-f]+)$")
   111  
   112  // ParseNode parses a node designator.
   113  //
   114  // There are two basic forms of node designators
   115  //   - incomplete nodes, which only have the public key (node ID)
   116  //   - complete nodes, which contain the public key and IP/Port information
   117  //
   118  // For incomplete nodes, the designator must look like one of these
   119  //
   120  //    enode://<hex node id>
   121  //    <hex node id>
   122  //
   123  // For complete nodes, the node ID is encoded in the username portion
   124  // of the URL, separated from the host by an @ sign. The hostname can
   125  // only be given as an IP address, DNS domain names are not allowed.
   126  // The port in the host name section is the TCP listening port. If the
   127  // TCP and UDP (discovery) ports differ, the UDP port is specified as
   128  // query parameter "discport".
   129  //
   130  // In the following example, the node URL describes
   131  // a node with IP address 10.3.58.6, TCP listening port 30303
   132  // and UDP discovery port 30301.
   133  //
   134  //    enode://<hex node id>@10.3.58.6:30303?discport=30301
   135  func ParseNode(rawurl string) (*Node, error) {
   136  	if m := incompleteNodeURL.FindStringSubmatch(rawurl); m != nil {
   137  		id, err := HexID(m[1])
   138  		if err != nil {
   139  			return nil, fmt.Errorf("invalid node ID (%v)", err)
   140  		}
   141  		return NewNode(id, nil, 0, 0), nil
   142  	}
   143  	return parseComplete(rawurl)
   144  }
   145  
   146  func parseComplete(rawurl string) (*Node, error) {
   147  	var (
   148  		id               NodeID
   149  		ip               net.IP
   150  		tcpPort, udpPort uint64
   151  	)
   152  	u, err := url.Parse(rawurl)
   153  	if err != nil {
   154  		return nil, err
   155  	}
   156  	if u.Scheme != "enode" {
   157  		return nil, errors.New("invalid URL scheme, want \"enode\"")
   158  	}
   159  	// Parse the Node ID from the user portion.
   160  	if u.User == nil {
   161  		return nil, errors.New("does not contain node ID")
   162  	}
   163  	if id, err = HexID(u.User.String()); err != nil {
   164  		return nil, fmt.Errorf("invalid node ID (%v)", err)
   165  	}
   166  	// Parse the IP address.
   167  	host, port, err := net.SplitHostPort(u.Host)
   168  	if err != nil {
   169  		return nil, fmt.Errorf("invalid host: %v", err)
   170  	}
   171  	if ip = net.ParseIP(host); ip == nil {
   172  		return nil, errors.New("invalid IP address")
   173  	}
   174  	// Ensure the IP is 4 bytes long for IPv4 addresses.
   175  	if ipv4 := ip.To4(); ipv4 != nil {
   176  		ip = ipv4
   177  	}
   178  	// Parse the port numbers.
   179  	if tcpPort, err = strconv.ParseUint(port, 10, 16); err != nil {
   180  		return nil, errors.New("invalid port")
   181  	}
   182  	udpPort = tcpPort
   183  	qv := u.Query()
   184  	if qv.Get("discport") != "" {
   185  		udpPort, err = strconv.ParseUint(qv.Get("discport"), 10, 16)
   186  		if err != nil {
   187  			return nil, errors.New("invalid discport in query")
   188  		}
   189  	}
   190  	return NewNode(id, ip, uint16(udpPort), uint16(tcpPort)), nil
   191  }
   192  
   193  // MustParseNode parses a node URL. It panics if the URL is not valid.
   194  func MustParseNode(rawurl string) *Node {
   195  	n, err := ParseNode(rawurl)
   196  	if err != nil {
   197  		panic("invalid node URL: " + err.Error())
   198  	}
   199  	return n
   200  }
   201  
   202  // MarshalText implements encoding.TextMarshaler.
   203  func (n *Node) MarshalText() ([]byte, error) {
   204  	return []byte(n.String()), nil
   205  }
   206  
   207  // UnmarshalText implements encoding.TextUnmarshaler.
   208  func (n *Node) UnmarshalText(text []byte) error {
   209  	dec, err := ParseNode(string(text))
   210  	if err == nil {
   211  		*n = *dec
   212  	}
   213  	return err
   214  }
   215  
   216  // type nodeQueue []*Node
   217  //
   218  // // pushNew adds n to the end if it is not present.
   219  // func (nl *nodeList) appendNew(n *Node) {
   220  // 	for _, entry := range n {
   221  // 		if entry == n {
   222  // 			return
   223  // 		}
   224  // 	}
   225  // 	*nq = append(*nq, n)
   226  // }
   227  //
   228  // // popRandom removes a random node. Nodes closer to
   229  // // to the head of the beginning of the have a slightly higher probability.
   230  // func (nl *nodeList) popRandom() *Node {
   231  // 	ix := rand.Intn(len(*nq))
   232  // 	//TODO: probability as mentioned above.
   233  // 	nl.removeIndex(ix)
   234  // }
   235  //
   236  // func (nl *nodeList) removeIndex(i int) *Node {
   237  // 	slice = *nl
   238  // 	if len(*slice) <= i {
   239  // 		return nil
   240  // 	}
   241  // 	*nl = append(slice[:i], slice[i+1:]...)
   242  // }
   243  
   244  const nodeIDBits = 32
   245  
   246  // NodeID is a unique identifier for each node.
   247  // The node identifier is a marshaled elliptic curve public key.
   248  type NodeID [32]byte
   249  
   250  // NodeID prints as a long hexadecimal number.
   251  func (n NodeID) String() string {
   252  	return fmt.Sprintf("%x", n[:])
   253  }
   254  
   255  // The Go syntax representation of a NodeID is a call to HexID.
   256  func (n NodeID) GoString() string {
   257  	return fmt.Sprintf("discover.HexID(\"%x\")", n[:])
   258  }
   259  
   260  // TerminalString returns a shortened hex string for terminal logging.
   261  func (n NodeID) TerminalString() string {
   262  	return hex.EncodeToString(n[:8])
   263  }
   264  
   265  // HexID converts a hex string to a NodeID.
   266  // The string may be prefixed with 0x.
   267  func HexID(in string) (NodeID, error) {
   268  	var id NodeID
   269  	b, err := hex.DecodeString(strings.TrimPrefix(in, "0x"))
   270  	if err != nil {
   271  		return id, err
   272  	} else if len(b) != len(id) {
   273  		return id, fmt.Errorf("wrong length, want %d hex chars", len(id)*2)
   274  	}
   275  	copy(id[:], b)
   276  	return id, nil
   277  }
   278  
   279  // ByteID converts a []byte to a NodeID.
   280  func ByteID(in []byte) NodeID {
   281  	var id NodeID
   282  	for i := range id {
   283  		id[i] = in[i]
   284  	}
   285  	return id
   286  }
   287  
   288  // MustHexID converts a hex string to a NodeID.
   289  // It panics if the string is not a valid NodeID.
   290  func MustHexID(in string) NodeID {
   291  	id, err := HexID(in)
   292  	if err != nil {
   293  		panic(err)
   294  	}
   295  	return id
   296  }
   297  
   298  // PubkeyID returns a marshaled representation of the given public key.
   299  func PubkeyID(pub *ecdsa.PublicKey) NodeID {
   300  	var id NodeID
   301  	pbytes := elliptic.Marshal(pub.Curve, pub.X, pub.Y)
   302  	if len(pbytes)-1 != len(id) {
   303  		panic(fmt.Errorf("need %d bit pubkey, got %d bits", (len(id)+1)*8, len(pbytes)))
   304  	}
   305  	copy(id[:], pbytes[1:])
   306  	return id
   307  }
   308  
   309  //// Pubkey returns the public key represented by the node ID.
   310  ////// It returns an error if the ID is not a point on the curve.
   311  //func (id NodeID) Pubkey() (*ecdsa.PublicKey, error) {
   312  //	p := &ecdsa.PublicKey{Curve: crypto.S256(), X: new(big.Int), Y: new(big.Int)}
   313  //	half := len(id) / 2
   314  //	p.X.SetBytes(id[:half])
   315  //	p.Y.SetBytes(id[half:])
   316  //	if !p.Curve.IsOnCurve(p.X, p.Y) {
   317  //		return nil, errors.New("id is invalid secp256k1 curve point")
   318  //	}
   319  //	return p, nil
   320  //}
   321  
   322  //func (id NodeID) mustPubkey() ecdsa.PublicKey {
   323  //	pk, err := id.Pubkey()
   324  //	if err != nil {
   325  //		panic(err)
   326  //	}
   327  //	return *pk
   328  //}
   329  
   330  // recoverNodeID computes the public key used to sign the
   331  // given hash from the signature.
   332  //func recoverNodeID(hash, sig []byte) (id NodeID, err error) {
   333  //	pubkey, err := crypto.Ecrecover(hash, sig)
   334  //	if err != nil {
   335  //		return id, err
   336  //	}
   337  //	if len(pubkey)-1 != len(id) {
   338  //		return id, fmt.Errorf("recovered pubkey has %d bits, want %d bits", len(pubkey)*8, (len(id)+1)*8)
   339  //	}
   340  //	for i := range id {
   341  //		id[i] = pubkey[i+1]
   342  //	}
   343  //	return id, nil
   344  //}
   345  
   346  // distcmp compares the distances a->target and b->target.
   347  // Returns -1 if a is closer to target, 1 if b is closer to target
   348  // and 0 if they are equal.
   349  func distcmp(target, a, b common.Hash) int {
   350  	for i := range target {
   351  		da := a[i] ^ target[i]
   352  		db := b[i] ^ target[i]
   353  		if da > db {
   354  			return 1
   355  		} else if da < db {
   356  			return -1
   357  		}
   358  	}
   359  	return 0
   360  }
   361  
   362  // table of leading zero counts for bytes [0..255]
   363  var lzcount = [256]int{
   364  	8, 7, 6, 6, 5, 5, 5, 5,
   365  	4, 4, 4, 4, 4, 4, 4, 4,
   366  	3, 3, 3, 3, 3, 3, 3, 3,
   367  	3, 3, 3, 3, 3, 3, 3, 3,
   368  	2, 2, 2, 2, 2, 2, 2, 2,
   369  	2, 2, 2, 2, 2, 2, 2, 2,
   370  	2, 2, 2, 2, 2, 2, 2, 2,
   371  	2, 2, 2, 2, 2, 2, 2, 2,
   372  	1, 1, 1, 1, 1, 1, 1, 1,
   373  	1, 1, 1, 1, 1, 1, 1, 1,
   374  	1, 1, 1, 1, 1, 1, 1, 1,
   375  	1, 1, 1, 1, 1, 1, 1, 1,
   376  	1, 1, 1, 1, 1, 1, 1, 1,
   377  	1, 1, 1, 1, 1, 1, 1, 1,
   378  	1, 1, 1, 1, 1, 1, 1, 1,
   379  	1, 1, 1, 1, 1, 1, 1, 1,
   380  	0, 0, 0, 0, 0, 0, 0, 0,
   381  	0, 0, 0, 0, 0, 0, 0, 0,
   382  	0, 0, 0, 0, 0, 0, 0, 0,
   383  	0, 0, 0, 0, 0, 0, 0, 0,
   384  	0, 0, 0, 0, 0, 0, 0, 0,
   385  	0, 0, 0, 0, 0, 0, 0, 0,
   386  	0, 0, 0, 0, 0, 0, 0, 0,
   387  	0, 0, 0, 0, 0, 0, 0, 0,
   388  	0, 0, 0, 0, 0, 0, 0, 0,
   389  	0, 0, 0, 0, 0, 0, 0, 0,
   390  	0, 0, 0, 0, 0, 0, 0, 0,
   391  	0, 0, 0, 0, 0, 0, 0, 0,
   392  	0, 0, 0, 0, 0, 0, 0, 0,
   393  	0, 0, 0, 0, 0, 0, 0, 0,
   394  	0, 0, 0, 0, 0, 0, 0, 0,
   395  	0, 0, 0, 0, 0, 0, 0, 0,
   396  }
   397  
   398  // logdist returns the logarithmic distance between a and b, log2(a ^ b).
   399  func logdist(a, b common.Hash) int {
   400  	lz := 0
   401  	for i := range a {
   402  		x := a[i] ^ b[i]
   403  		if x == 0 {
   404  			lz += 8
   405  		} else {
   406  			lz += lzcount[x]
   407  			break
   408  		}
   409  	}
   410  	return len(a)*8 - lz
   411  }
   412  
   413  // hashAtDistance returns a random hash such that logdist(a, b) == n
   414  func hashAtDistance(a common.Hash, n int) (b common.Hash) {
   415  	if n == 0 {
   416  		return a
   417  	}
   418  	// flip bit at position n, fill the rest with random bits
   419  	b = a
   420  	pos := len(a) - n/8 - 1
   421  	bit := byte(0x01) << (byte(n%8) - 1)
   422  	if bit == 0 {
   423  		pos++
   424  		bit = 0x80
   425  	}
   426  	b[pos] = a[pos]&^bit | ^a[pos]&bit // TODO: randomize end bits
   427  	for i := pos + 1; i < len(a); i++ {
   428  		b[i] = byte(rand.New(rand.NewSource(time.Now().UnixNano())).Intn(255))
   429  	}
   430  	return b
   431  }