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-rw-r--r--p2p/discover/node.go289
1 files changed, 289 insertions, 0 deletions
diff --git a/p2p/discover/node.go b/p2p/discover/node.go
new file mode 100644
index 000000000..a49a2f547
--- /dev/null
+++ b/p2p/discover/node.go
@@ -0,0 +1,289 @@
+package discover
+
+import (
+ "crypto/ecdsa"
+ "crypto/elliptic"
+ "encoding/hex"
+ "errors"
+ "fmt"
+ "io"
+ "math/rand"
+ "net"
+ "net/url"
+ "strconv"
+ "strings"
+ "time"
+
+ "github.com/ethereum/go-ethereum/crypto/secp256k1"
+ "github.com/ethereum/go-ethereum/rlp"
+)
+
+// Node represents a host on the network.
+type Node struct {
+ ID NodeID
+ IP net.IP
+
+ DiscPort int // UDP listening port for discovery protocol
+ TCPPort int // TCP listening port for RLPx
+
+ active time.Time
+}
+
+func newNode(id NodeID, addr *net.UDPAddr) *Node {
+ return &Node{
+ ID: id,
+ IP: addr.IP,
+ DiscPort: addr.Port,
+ TCPPort: addr.Port,
+ active: time.Now(),
+ }
+}
+
+func (n *Node) isValid() bool {
+ // TODO: don't accept localhost, LAN addresses from internet hosts
+ return !n.IP.IsMulticast() && !n.IP.IsUnspecified() && n.TCPPort != 0 && n.DiscPort != 0
+}
+
+// The string representation of a Node is a URL.
+// Please see ParseNode for a description of the format.
+func (n *Node) String() string {
+ addr := net.TCPAddr{IP: n.IP, Port: n.TCPPort}
+ u := url.URL{
+ Scheme: "enode",
+ User: url.User(fmt.Sprintf("%x", n.ID[:])),
+ Host: addr.String(),
+ }
+ if n.DiscPort != n.TCPPort {
+ u.RawQuery = "discport=" + strconv.Itoa(n.DiscPort)
+ }
+ return u.String()
+}
+
+// ParseNode parses a node URL.
+//
+// A node URL has scheme "enode".
+//
+// The hexadecimal node ID is encoded in the username portion of the
+// URL, separated from the host by an @ sign. The hostname can only be
+// given as an IP address, DNS domain names are not allowed. The port
+// in the host name section is the TCP listening port. If the TCP and
+// UDP (discovery) ports differ, the UDP port is specified as query
+// parameter "discport".
+//
+// In the following example, the node URL describes
+// a node with IP address 10.3.58.6, TCP listening port 30303
+// and UDP discovery port 30301.
+//
+// enode://<hex node id>@10.3.58.6:30303?discport=30301
+func ParseNode(rawurl string) (*Node, error) {
+ var n Node
+ u, err := url.Parse(rawurl)
+ if u.Scheme != "enode" {
+ return nil, errors.New("invalid URL scheme, want \"enode\"")
+ }
+ if u.User == nil {
+ return nil, errors.New("does not contain node ID")
+ }
+ if n.ID, err = HexID(u.User.String()); err != nil {
+ return nil, fmt.Errorf("invalid node ID (%v)", err)
+ }
+ ip, port, err := net.SplitHostPort(u.Host)
+ if err != nil {
+ return nil, fmt.Errorf("invalid host: %v", err)
+ }
+ if n.IP = net.ParseIP(ip); n.IP == nil {
+ return nil, errors.New("invalid IP address")
+ }
+ if n.TCPPort, err = strconv.Atoi(port); err != nil {
+ return nil, errors.New("invalid port")
+ }
+ qv := u.Query()
+ if qv.Get("discport") == "" {
+ n.DiscPort = n.TCPPort
+ } else {
+ if n.DiscPort, err = strconv.Atoi(qv.Get("discport")); err != nil {
+ return nil, errors.New("invalid discport in query")
+ }
+ }
+ return &n, nil
+}
+
+// MustParseNode parses a node URL. It panics if the URL is not valid.
+func MustParseNode(rawurl string) *Node {
+ n, err := ParseNode(rawurl)
+ if err != nil {
+ panic("invalid node URL: " + err.Error())
+ }
+ return n
+}
+
+func (n Node) EncodeRLP(w io.Writer) error {
+ return rlp.Encode(w, rpcNode{IP: n.IP.String(), Port: uint16(n.TCPPort), ID: n.ID})
+}
+func (n *Node) DecodeRLP(s *rlp.Stream) (err error) {
+ var ext rpcNode
+ if err = s.Decode(&ext); err == nil {
+ n.TCPPort = int(ext.Port)
+ n.DiscPort = int(ext.Port)
+ n.ID = ext.ID
+ if n.IP = net.ParseIP(ext.IP); n.IP == nil {
+ return errors.New("invalid IP string")
+ }
+ }
+ return err
+}
+
+// NodeID is a unique identifier for each node.
+// The node identifier is a marshaled elliptic curve public key.
+type NodeID [512 / 8]byte
+
+// NodeID prints as a long hexadecimal number.
+func (n NodeID) String() string {
+ return fmt.Sprintf("%#x", n[:])
+}
+
+// The Go syntax representation of a NodeID is a call to HexID.
+func (n NodeID) GoString() string {
+ return fmt.Sprintf("discover.HexID(\"%#x\")", n[:])
+}
+
+// HexID converts a hex string to a NodeID.
+// The string may be prefixed with 0x.
+func HexID(in string) (NodeID, error) {
+ if strings.HasPrefix(in, "0x") {
+ in = in[2:]
+ }
+ var id NodeID
+ b, err := hex.DecodeString(in)
+ if err != nil {
+ return id, err
+ } else if len(b) != len(id) {
+ return id, fmt.Errorf("wrong length, need %d hex bytes", len(id))
+ }
+ copy(id[:], b)
+ return id, nil
+}
+
+// MustHexID converts a hex string to a NodeID.
+// It panics if the string is not a valid NodeID.
+func MustHexID(in string) NodeID {
+ id, err := HexID(in)
+ if err != nil {
+ panic(err)
+ }
+ return id
+}
+
+// PubkeyID returns a marshaled representation of the given public key.
+func PubkeyID(pub *ecdsa.PublicKey) NodeID {
+ var id NodeID
+ pbytes := elliptic.Marshal(pub.Curve, pub.X, pub.Y)
+ if len(pbytes)-1 != len(id) {
+ panic(fmt.Errorf("need %d bit pubkey, got %d bits", (len(id)+1)*8, len(pbytes)))
+ }
+ copy(id[:], pbytes[1:])
+ return id
+}
+
+// recoverNodeID computes the public key used to sign the
+// given hash from the signature.
+func recoverNodeID(hash, sig []byte) (id NodeID, err error) {
+ pubkey, err := secp256k1.RecoverPubkey(hash, sig)
+ if err != nil {
+ return id, err
+ }
+ if len(pubkey)-1 != len(id) {
+ return id, fmt.Errorf("recovered pubkey has %d bits, want %d bits", len(pubkey)*8, (len(id)+1)*8)
+ }
+ for i := range id {
+ id[i] = pubkey[i+1]
+ }
+ return id, nil
+}
+
+// distcmp compares the distances a->target and b->target.
+// Returns -1 if a is closer to target, 1 if b is closer to target
+// and 0 if they are equal.
+func distcmp(target, a, b NodeID) int {
+ for i := range target {
+ da := a[i] ^ target[i]
+ db := b[i] ^ target[i]
+ if da > db {
+ return 1
+ } else if da < db {
+ return -1
+ }
+ }
+ return 0
+}
+
+// table of leading zero counts for bytes [0..255]
+var lzcount = [256]int{
+ 8, 7, 6, 6, 5, 5, 5, 5,
+ 4, 4, 4, 4, 4, 4, 4, 4,
+ 3, 3, 3, 3, 3, 3, 3, 3,
+ 3, 3, 3, 3, 3, 3, 3, 3,
+ 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2,
+ 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0,
+}
+
+// logdist returns the logarithmic distance between a and b, log2(a ^ b).
+func logdist(a, b NodeID) int {
+ lz := 0
+ for i := range a {
+ x := a[i] ^ b[i]
+ if x == 0 {
+ lz += 8
+ } else {
+ lz += lzcount[x]
+ break
+ }
+ }
+ return len(a)*8 - lz
+}
+
+// randomID returns a random NodeID such that logdist(a, b) == n
+func randomID(a NodeID, n int) (b NodeID) {
+ if n == 0 {
+ return a
+ }
+ // flip bit at position n, fill the rest with random bits
+ b = a
+ pos := len(a) - n/8 - 1
+ bit := byte(0x01) << (byte(n%8) - 1)
+ if bit == 0 {
+ pos++
+ bit = 0x80
+ }
+ b[pos] = a[pos]&^bit | ^a[pos]&bit // TODO: randomize end bits
+ for i := pos + 1; i < len(a); i++ {
+ b[i] = byte(rand.Intn(255))
+ }
+ return b
+}