1 files changed, 423 insertions, 0 deletions
diff --git a/p2p/discv5/node.go b/p2p/discv5/node.go
new file mode 100644
index 000000000..b6b6f149d
--- /dev/null
+++ b/p2p/discv5/node.go
@@ -0,0 +1,423 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package discv5
+
+import (
+	"bytes"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"math/big"
+	"math/rand"
+	"net"
+	"net/url"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+// Node represents a host on the network.
+// The public fields of Node may not be modified.
+type Node struct {
+	IP       net.IP // len 4 for IPv4 or 16 for IPv6
+	UDP, TCP uint16 // port numbers
+	ID       NodeID // the node's public key
+
+	// Network-related fields are contained in nodeNetGuts.
+	// These fields are not supposed to be used off the
+	// Network.loop goroutine.
+	nodeNetGuts
+}
+
+// NewNode creates a new node. It is mostly meant to be used for
+// testing purposes.
+func NewNode(id NodeID, ip net.IP, udpPort, tcpPort uint16) *Node {
+	if ipv4 := ip.To4(); ipv4 != nil {
+		ip = ipv4
+	}
+	return &Node{
+		IP:          ip,
+		UDP:         udpPort,
+		TCP:         tcpPort,
+		ID:          id,
+		nodeNetGuts: nodeNetGuts{sha: crypto.Keccak256Hash(id[:])},
+	}
+}
+
+func (n *Node) addr() *net.UDPAddr {
+	return &net.UDPAddr{IP: n.IP, Port: int(n.UDP)}
+}
+
+func (n *Node) setAddr(a *net.UDPAddr) {
+	n.IP = a.IP
+	if ipv4 := a.IP.To4(); ipv4 != nil {
+		n.IP = ipv4
+	}
+	n.UDP = uint16(a.Port)
+}
+
+// compares the given address against the stored values.
+func (n *Node) addrEqual(a *net.UDPAddr) bool {
+	ip := a.IP
+	if ipv4 := a.IP.To4(); ipv4 != nil {
+		ip = ipv4
+	}
+	return n.UDP == uint16(a.Port) && bytes.Equal(n.IP, ip)
+}
+
+// Incomplete returns true for nodes with no IP address.
+func (n *Node) Incomplete() bool {
+	return n.IP == nil
+}
+
+// checks whether n is a valid complete node.
+func (n *Node) validateComplete() error {
+	if n.Incomplete() {
+		return errors.New("incomplete node")
+	}
+	if n.UDP == 0 {
+		return errors.New("missing UDP port")
+	}
+	if n.TCP == 0 {
+		return errors.New("missing TCP port")
+	}
+	if n.IP.IsMulticast() || n.IP.IsUnspecified() {
+		return errors.New("invalid IP (multicast/unspecified)")
+	}
+	_, err := n.ID.Pubkey() // validate the key (on curve, etc.)
+	return err
+}
+
+// The string representation of a Node is a URL.
+// Please see ParseNode for a description of the format.
+func (n *Node) String() string {
+	u := url.URL{Scheme: "enode"}
+	if n.Incomplete() {
+		u.Host = fmt.Sprintf("%x", n.ID[:])
+	} else {
+		addr := net.TCPAddr{IP: n.IP, Port: int(n.TCP)}
+		u.User = url.User(fmt.Sprintf("%x", n.ID[:]))
+		u.Host = addr.String()
+		if n.UDP != n.TCP {
+			u.RawQuery = "discport=" + strconv.Itoa(int(n.UDP))
+		}
+	}
+	return u.String()
+}
+
+var incompleteNodeURL = regexp.MustCompile("(?i)^(?:enode://)?([0-9a-f]+)$")
+
+// ParseNode parses a node designator.
+//
+// There are two basic forms of node designators
+//   - incomplete nodes, which only have the public key (node ID)
+//   - complete nodes, which contain the public key and IP/Port information
+//
+// For incomplete nodes, the designator must look like one of these
+//
+//    enode://<hex node id>
+//    <hex node id>
+//
+// For complete nodes, the 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) {
+	if m := incompleteNodeURL.FindStringSubmatch(rawurl); m != nil {
+		id, err := HexID(m[1])
+		if err != nil {
+			return nil, fmt.Errorf("invalid node ID (%v)", err)
+		}
+		return NewNode(id, nil, 0, 0), nil
+	}
+	return parseComplete(rawurl)
+}
+
+func parseComplete(rawurl string) (*Node, error) {
+	var (
+		id               NodeID
+		ip               net.IP
+		tcpPort, udpPort uint64
+	)
+	u, err := url.Parse(rawurl)
+	if err != nil {
+		return nil, err
+	}
+	if u.Scheme != "enode" {
+		return nil, errors.New("invalid URL scheme, want \"enode\"")
+	}
+	// Parse the Node ID from the user portion.
+	if u.User == nil {
+		return nil, errors.New("does not contain node ID")
+	}
+	if id, err = HexID(u.User.String()); err != nil {
+		return nil, fmt.Errorf("invalid node ID (%v)", err)
+	}
+	// Parse the IP address.
+	host, port, err := net.SplitHostPort(u.Host)
+	if err != nil {
+		return nil, fmt.Errorf("invalid host: %v", err)
+	}
+	if ip = net.ParseIP(host); ip == nil {
+		return nil, errors.New("invalid IP address")
+	}
+	// Ensure the IP is 4 bytes long for IPv4 addresses.
+	if ipv4 := ip.To4(); ipv4 != nil {
+		ip = ipv4
+	}
+	// Parse the port numbers.
+	if tcpPort, err = strconv.ParseUint(port, 10, 16); err != nil {
+		return nil, errors.New("invalid port")
+	}
+	udpPort = tcpPort
+	qv := u.Query()
+	if qv.Get("discport") != "" {
+		udpPort, err = strconv.ParseUint(qv.Get("discport"), 10, 16)
+		if err != nil {
+			return nil, errors.New("invalid discport in query")
+		}
+	}
+	return NewNode(id, ip, uint16(udpPort), uint16(tcpPort)), 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
+}
+
+// type nodeQueue []*Node
+//
+// // pushNew adds n to the end if it is not present.
+// func (nl *nodeList) appendNew(n *Node) {
+// 	for _, entry := range n {
+// 		if entry == n {
+// 			return
+// 		}
+// 	}
+// 	*nq = append(*nq, n)
+// }
+//
+// // popRandom removes a random node. Nodes closer to
+// // to the head of the beginning of the have a slightly higher probability.
+// func (nl *nodeList) popRandom() *Node {
+// 	ix := rand.Intn(len(*nq))
+// 	//TODO: probability as mentioned above.
+// 	nl.removeIndex(ix)
+// }
+//
+// func (nl *nodeList) removeIndex(i int) *Node {
+// 	slice = *nl
+// 	if len(*slice) <= i {
+// 		return nil
+// 	}
+// 	*nl = append(slice[:i], slice[i+1:]...)
+// }
+
+const nodeIDBits = 512
+
+// NodeID is a unique identifier for each node.
+// The node identifier is a marshaled elliptic curve public key.
+type NodeID [nodeIDBits / 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, want %d hex chars", len(id)*2)
+	}
+	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
+}
+
+// Pubkey returns the public key represented by the node ID.
+// It returns an error if the ID is not a point on the curve.
+func (id NodeID) Pubkey() (*ecdsa.PublicKey, error) {
+	p := &ecdsa.PublicKey{Curve: S256(), X: new(big.Int), Y: new(big.Int)}
+	half := len(id) / 2
+	p.X.SetBytes(id[:half])
+	p.Y.SetBytes(id[half:])
+	if !p.Curve.IsOnCurve(p.X, p.Y) {
+		return nil, errors.New("id is invalid secp256k1 curve point")
+	}
+	return p, nil
+}
+
+func (id NodeID) mustPubkey() ecdsa.PublicKey {
+	pk, err := id.Pubkey()
+	if err != nil {
+		panic(err)
+	}
+	return *pk
+}
+
+// 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 := crypto.Ecrecover(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 common.Hash) 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 common.Hash) 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
+}
+
+// hashAtDistance returns a random hash such that logdist(a, b) == n
+func hashAtDistance(a common.Hash, n int) (b common.Hash) {
+	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
+}