1 files changed, 248 insertions, 0 deletions
diff --git a/p2p/enode/node.go b/p2p/enode/node.go
new file mode 100644
index 000000000..84088fcd2
--- /dev/null
+++ b/p2p/enode/node.go
@@ -0,0 +1,248 @@
+// 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/ethereum/go-ethereum/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
+}
+
+// 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
+}