292 lines
7.0 KiB
Go
292 lines
7.0 KiB
Go
package discover
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import (
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"crypto/ecdsa"
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"crypto/elliptic"
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"encoding/hex"
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"errors"
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"fmt"
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"io"
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"math/rand"
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"net"
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"net/url"
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"strconv"
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"strings"
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"time"
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"github.com/ethereum/go-ethereum/crypto/secp256k1"
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"github.com/ethereum/go-ethereum/rlp"
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)
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const nodeIDBits = 512
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// Node represents a host on the network.
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type Node struct {
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ID NodeID
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IP net.IP
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DiscPort int // UDP listening port for discovery protocol
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TCPPort int // TCP listening port for RLPx
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active time.Time
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}
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func newNode(id NodeID, addr *net.UDPAddr) *Node {
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return &Node{
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ID: id,
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IP: addr.IP,
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DiscPort: addr.Port,
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TCPPort: addr.Port,
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active: time.Now(),
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}
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}
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func (n *Node) isValid() bool {
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// TODO: don't accept localhost, LAN addresses from internet hosts
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return !n.IP.IsMulticast() && !n.IP.IsUnspecified() && n.TCPPort != 0 && n.DiscPort != 0
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}
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// The string representation of a Node is a URL.
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// Please see ParseNode for a description of the format.
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func (n *Node) String() string {
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addr := net.TCPAddr{IP: n.IP, Port: n.TCPPort}
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u := url.URL{
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Scheme: "enode",
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User: url.User(fmt.Sprintf("%x", n.ID[:])),
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Host: addr.String(),
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}
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if n.DiscPort != n.TCPPort {
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u.RawQuery = "discport=" + strconv.Itoa(n.DiscPort)
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}
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return u.String()
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}
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// ParseNode parses a node URL.
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//
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// A node URL has scheme "enode".
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//
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// The hexadecimal node ID is encoded in the username portion of the
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// URL, separated from the host by an @ sign. The hostname can only be
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// given as an IP address, DNS domain names are not allowed. The port
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// in the host name section is the TCP listening port. If the TCP and
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// UDP (discovery) ports differ, the UDP port is specified as query
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// parameter "discport".
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//
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// In the following example, the node URL describes
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// a node with IP address 10.3.58.6, TCP listening port 30303
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// and UDP discovery port 30301.
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//
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// enode://<hex node id>@10.3.58.6:30303?discport=30301
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func ParseNode(rawurl string) (*Node, error) {
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var n Node
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u, err := url.Parse(rawurl)
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if u.Scheme != "enode" {
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return nil, errors.New("invalid URL scheme, want \"enode\"")
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}
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if u.User == nil {
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return nil, errors.New("does not contain node ID")
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}
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if n.ID, err = HexID(u.User.String()); err != nil {
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return nil, fmt.Errorf("invalid node ID (%v)", err)
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}
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ip, port, err := net.SplitHostPort(u.Host)
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if err != nil {
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return nil, fmt.Errorf("invalid host: %v", err)
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}
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if n.IP = net.ParseIP(ip); n.IP == nil {
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return nil, errors.New("invalid IP address")
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}
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if n.TCPPort, err = strconv.Atoi(port); err != nil {
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return nil, errors.New("invalid port")
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}
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qv := u.Query()
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if qv.Get("discport") == "" {
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n.DiscPort = n.TCPPort
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} else {
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if n.DiscPort, err = strconv.Atoi(qv.Get("discport")); err != nil {
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return nil, errors.New("invalid discport in query")
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}
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}
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return &n, nil
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}
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// MustParseNode parses a node URL. It panics if the URL is not valid.
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func MustParseNode(rawurl string) *Node {
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n, err := ParseNode(rawurl)
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if err != nil {
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panic("invalid node URL: " + err.Error())
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}
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return n
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}
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func (n Node) EncodeRLP(w io.Writer) error {
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return rlp.Encode(w, rpcNode{IP: n.IP.String(), Port: uint16(n.TCPPort), ID: n.ID})
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}
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func (n *Node) DecodeRLP(s *rlp.Stream) (err error) {
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var ext rpcNode
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if err = s.Decode(&ext); err == nil {
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n.TCPPort = int(ext.Port)
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n.DiscPort = int(ext.Port)
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n.ID = ext.ID
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if n.IP = net.ParseIP(ext.IP); n.IP == nil {
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return errors.New("invalid IP string")
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}
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}
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return err
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}
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// NodeID is a unique identifier for each node.
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// The node identifier is a marshaled elliptic curve public key.
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type NodeID [nodeIDBits / 8]byte
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// NodeID prints as a long hexadecimal number.
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func (n NodeID) String() string {
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return fmt.Sprintf("%#x", n[:])
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}
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// The Go syntax representation of a NodeID is a call to HexID.
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func (n NodeID) GoString() string {
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return fmt.Sprintf("discover.HexID(\"%#x\")", n[:])
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}
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// HexID converts a hex string to a NodeID.
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// The string may be prefixed with 0x.
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func HexID(in string) (NodeID, error) {
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if strings.HasPrefix(in, "0x") {
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in = in[2:]
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}
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var id NodeID
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b, err := hex.DecodeString(in)
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if err != nil {
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return id, err
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} else if len(b) != len(id) {
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return id, fmt.Errorf("wrong length, need %d hex bytes", len(id))
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}
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copy(id[:], b)
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return id, nil
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}
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// MustHexID converts a hex string to a NodeID.
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// It panics if the string is not a valid NodeID.
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func MustHexID(in string) NodeID {
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id, err := HexID(in)
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if err != nil {
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panic(err)
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}
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return id
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}
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// PubkeyID returns a marshaled representation of the given public key.
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func PubkeyID(pub *ecdsa.PublicKey) NodeID {
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var id NodeID
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pbytes := elliptic.Marshal(pub.Curve, pub.X, pub.Y)
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if len(pbytes)-1 != len(id) {
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panic(fmt.Errorf("need %d bit pubkey, got %d bits", (len(id)+1)*8, len(pbytes)))
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}
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copy(id[:], pbytes[1:])
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return id
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}
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// recoverNodeID computes the public key used to sign the
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// given hash from the signature.
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func recoverNodeID(hash, sig []byte) (id NodeID, err error) {
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pubkey, err := secp256k1.RecoverPubkey(hash, sig)
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if err != nil {
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return id, err
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}
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if len(pubkey)-1 != len(id) {
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return id, fmt.Errorf("recovered pubkey has %d bits, want %d bits", len(pubkey)*8, (len(id)+1)*8)
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}
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for i := range id {
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id[i] = pubkey[i+1]
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}
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return id, nil
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}
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// distcmp compares the distances a->target and b->target.
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// Returns -1 if a is closer to target, 1 if b is closer to target
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// and 0 if they are equal.
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func distcmp(target, a, b NodeID) int {
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for i := range target {
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da := a[i] ^ target[i]
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db := b[i] ^ target[i]
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if da > db {
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return 1
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} else if da < db {
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return -1
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}
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}
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return 0
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}
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// table of leading zero counts for bytes [0..255]
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var lzcount = [256]int{
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8, 7, 6, 6, 5, 5, 5, 5,
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4, 4, 4, 4, 4, 4, 4, 4,
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3, 3, 3, 3, 3, 3, 3, 3,
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3, 3, 3, 3, 3, 3, 3, 3,
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2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2,
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1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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}
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// logdist returns the logarithmic distance between a and b, log2(a ^ b).
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func logdist(a, b NodeID) int {
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lz := 0
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for i := range a {
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x := a[i] ^ b[i]
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if x == 0 {
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lz += 8
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} else {
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lz += lzcount[x]
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break
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}
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}
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return len(a)*8 - lz
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}
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// randomID returns a random NodeID such that logdist(a, b) == n
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func randomID(a NodeID, n int) (b NodeID) {
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if n == 0 {
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return a
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}
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// flip bit at position n, fill the rest with random bits
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b = a
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pos := len(a) - n/8 - 1
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bit := byte(0x01) << (byte(n%8) - 1)
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if bit == 0 {
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pos++
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bit = 0x80
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}
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b[pos] = a[pos]&^bit | ^a[pos]&bit // TODO: randomize end bits
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for i := pos + 1; i < len(a); i++ {
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b[i] = byte(rand.Intn(255))
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}
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return b
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}
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