// Copyright 2018 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 enode
import (
"crypto/ecdsa"
"encoding/hex"
"errors"
"fmt"
"math/bits"
"math/rand"
"net"
"strings"
"github.com/dexon-foundation/dexon/p2p/enr"
)
// Node represents a host on the network.
type Node struct {
r enr.Record
id ID
}
// New wraps a node record. The record must be valid according to the given
// identity scheme.
func New(validSchemes enr.IdentityScheme, r *enr.Record) (*Node, error) {
if err := r.VerifySignature(validSchemes); err != nil {
return nil, err
}
node := &Node{r: *r}
if n := copy(node.id[:], validSchemes.NodeAddr(&node.r)); n != len(ID{}) {
return nil, fmt.Errorf("invalid node ID length %d, need %d", n, len(ID{}))
}
return node, nil
}
// ID returns the node identifier.
func (n *Node) ID() ID {
return n.id
}
// Seq returns the sequence number of the underlying record.
func (n *Node) Seq() uint64 {
return n.r.Seq()
}
// Incomplete returns true for nodes with no IP address.
func (n *Node) Incomplete() bool {
return n.IP() == nil
}
// Load retrieves an entry from the underlying record.
func (n *Node) Load(k enr.Entry) error {
return n.r.Load(k)
}
// IP returns the IP address of the node.
func (n *Node) IP() net.IP {
var ip net.IP
n.Load((*enr.IP)(&ip))
return ip
}
// UDP returns the UDP port of the node.
func (n *Node) UDP() int {
var port enr.UDP
n.Load(&port)
return int(port)
}
// UDP returns the TCP port of the node.
func (n *Node) TCP() int {
var port enr.TCP
n.Load(&port)
return int(port)
}
// Pubkey returns the secp256k1 public key of the node, if present.
func (n *Node) Pubkey() *ecdsa.PublicKey {
var key ecdsa.PublicKey
if n.Load((*Secp256k1)(&key)) != nil {
return nil
}
return &key
}
// Record returns the node's record. The return value is a copy and may
// be modified by the caller.
func (n *Node) Record() *enr.Record {
cpy := n.r
return &cpy
}
// 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")
}
ip := n.IP()
if ip.IsMulticast() || ip.IsUnspecified() {
return errors.New("invalid IP (multicast/unspecified)")
}
// Validate the node key (on curve, etc.).
var key Secp256k1
return n.Load(&key)
}
// The string representation of a Node is a URL.
// Please see ParseNode for a description of the format.
func (n *Node) String() string {
return n.v4URL()
}
// MarshalText implements encoding.TextMarshaler.
func (n *Node) MarshalText() ([]byte, error) {
return []byte(n.v4URL()), nil
}
// UnmarshalText implements encoding.TextUnmarshaler.
func (n *Node) UnmarshalText(text []byte) error {
dec, err := ParseV4(string(text))
if err == nil {
*n = *dec
}
return err
}
// ID is a unique identifier for each node.
type ID [32]byte
// Bytes returns a byte slice representation of the ID
func (n ID) Bytes() []byte {
return n[:]
}
// ID prints as a long hexadecimal number.
func (n ID) String() string {
return fmt.Sprintf("%x", n[:])
}
// The Go syntax representation of a ID is a call to HexID.
func (n ID) GoString() string {
return fmt.Sprintf("enode.HexID(\"%x\")", n[:])
}
// TerminalString returns a shortened hex string for terminal logging.
func (n ID) TerminalString() string {
return hex.EncodeToString(n[:8])
}
// MarshalText implements the encoding.TextMarshaler interface.
func (n ID) MarshalText() ([]byte, error) {
return []byte(hex.EncodeToString(n[:])), nil
}
// UnmarshalText implements the encoding.TextUnmarshaler interface.
func (n *ID) UnmarshalText(text []byte) error {
id, err := parseID(string(text))
if err != nil {
return err
}
*n = id
return nil
}
// HexID converts a hex string to an ID.
// The string may be prefixed with 0x.
// It panics if the string is not a valid ID.
func HexID(in string) ID {
id, err := parseID(in)
if err != nil {
panic(err)
}
return id
}
func parseID(in string) (ID, error) {
var id ID
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
}
// 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 ID) 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
}
// LogDist returns the logarithmic distance between a and b, log2(a ^ b).
func LogDist(a, b ID) int {
lz := 0
for i := range a {
x := a[i] ^ b[i]
if x == 0 {
lz += 8
} else {
lz += bits.LeadingZeros8(x)
break
}
}
return len(a)*8 - lz
}
// RandomID returns a random ID b such that logdist(a, b) == n.
func RandomID(a ID, n int) (b ID) {
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
}
