// 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 (
"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) && n.IP.Equal(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) {
var id NodeID
b, err := hex.DecodeString(strings.TrimPrefix(in, "0x"))
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
}
