github.com/ethereumproject/go-ethereum@v5.5.2+incompatible/p2p/discover/node.go

// 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 discover

import (
	"crypto/ecdsa"
	"crypto/elliptic"
	"encoding/hex"
	"errors"
	"fmt"
	"math/big"
	"net"
	"net/url"
	"regexp"
	"strconv"
	"strings"

	"time"

	"github.com/ethereumproject/go-ethereum/common"
	"github.com/ethereumproject/go-ethereum/crypto"
	"github.com/ethereumproject/go-ethereum/crypto/secp256k1"
)

const nodeIDBits = 512

// Node represents a host on the network.
// The fields of Node may not be modified.
type Node struct {
	IP net.IP `json:"ip"` // len 4 for IPv4 or 16 for IPv6
	// port numbers
	UDP uint16 `json:"udp"`
	TCP uint16 `json:"tcp"`
	ID  NodeID `json:"node_id"` // the node's public key

	// This is a cached copy of sha3(ID) which is used for node
	// distance calculations. This is part of Node in order to make it
	// possible to write tests that need a node at a certain distance.
	// In those tests, the content of sha will not actually correspond
	// with ID.
	sha common.Hash `json:"sha"`

	// whether this node is currently being pinged in order to replace
	// it in a bucket
	contested bool `json:"contested"`

	// Time when the node was added to the table.
	addedAt time.Time
}

// 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,
		sha: crypto.Keccak256Hash(id[:]),
	}
}

func (n *Node) addr() *net.UDPAddr {
	return &net.UDPAddr{IP: n.IP, Port: int(n.UDP)}
}

// 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
}

// 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: secp256k1.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
}

// 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
}