all: new p2p node representation (#17643)

Package p2p/enode provides a generalized representation of p2p nodes
which can contain arbitrary information in key/value pairs. It is also
the new home for the node database. The "v4" identity scheme is also
moved here from p2p/enr to remove the dependency on Ethereum crypto from
that package.

Record signature handling is changed significantly. The identity scheme
registry is removed and acceptable schemes must be passed to any method
that needs identity. This means records must now be validated explicitly
after decoding.

The enode API is designed to make signature handling easy and safe: most
APIs around the codebase work with enode.Node, which is a wrapper around
a valid record. Going from enr.Record to enode.Node requires a valid
signature.

* p2p/discover: port to p2p/enode

This ports the discovery code to the new node representation in
p2p/enode. The wire protocol is unchanged, this can be considered a
refactoring change. The Kademlia table can now deal with nodes using an
arbitrary identity scheme. This requires a few incompatible API changes:

  - Table.Lookup is not available anymore. It used to take a public key
    as argument because v4 protocol requires one. Its replacement is
    LookupRandom.
  - Table.Resolve takes *enode.Node instead of NodeID. This is also for
    v4 protocol compatibility because nodes cannot be looked up by ID
    alone.
  - Types Node and NodeID are gone. Further commits in the series will be
    fixes all over the the codebase to deal with those removals.

* p2p: port to p2p/enode and discovery changes

This adapts package p2p to the changes in p2p/discover. All uses of
discover.Node and discover.NodeID are replaced by their equivalents from
p2p/enode.

New API is added to retrieve the enode.Node instance of a peer. The
behavior of Server.Self with discovery disabled is improved. It now
tries much harder to report a working IP address, falling back to
127.0.0.1 if no suitable address can be determined through other means.
These changes were needed for tests of other packages later in the
series.

* p2p/simulations, p2p/testing: port to p2p/enode

No surprises here, mostly replacements of discover.Node, discover.NodeID
with their new equivalents. The 'interesting' API changes are:

 - testing.ProtocolSession tracks complete nodes, not just their IDs.
 - adapters.NodeConfig has a new method to create a complete node.

These changes were needed to make swarm tests work.

Note that the NodeID change makes the code incompatible with old
simulation snapshots.

* whisper/whisperv5, whisper/whisperv6: port to p2p/enode

This port was easy because whisper uses []byte for node IDs and
URL strings in the API.

* eth: port to p2p/enode

Again, easy to port because eth uses strings for node IDs and doesn't
care about node information in any way.

* les: port to p2p/enode

Apart from replacing discover.NodeID with enode.ID, most changes are in
the server pool code. It now deals with complete nodes instead
of (Pubkey, IP, Port) triples. The database format is unchanged for now,
but we should probably change it to use the node database later.

* node: port to p2p/enode

This change simply replaces discover.Node and discover.NodeID with their
new equivalents.

* swarm/network: port to p2p/enode

Swarm has its own node address representation, BzzAddr, containing both
an overlay address (the hash of a secp256k1 public key) and an underlay
address (enode:// URL).

There are no changes to the BzzAddr format in this commit, but certain
operations such as creating a BzzAddr from a node ID are now impossible
because node IDs aren't public keys anymore.

Most swarm-related changes in the series remove uses of
NewAddrFromNodeID, replacing it with NewAddr which takes a complete node
as argument. ToOverlayAddr is removed because we can just use the node
ID directly.

1 files changed, 194 insertions, 0 deletions

diff --git a/p2p/enode/urlv4.go b/p2p/enode/urlv4.go
new file mode 100644
index 000000000..50e9485d0
--- /dev/null
+++ b/p2p/enode/urlv4.go
@@ -0,0 +1,194 @@
+// 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"
+	"net"
+	"net/url"
+	"regexp"
+	"strconv"
+
+	"github.com/ethereum/go-ethereum/common/math"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/p2p/enr"
+)
+
+var incompleteNodeURL = regexp.MustCompile("(?i)^(?:enode://)?([0-9a-f]+)$")
+
+// MustParseV4 parses a node URL. It panics if the URL is not valid.
+func MustParseV4(rawurl string) *Node {
+	n, err := ParseV4(rawurl)
+	if err != nil {
+		panic("invalid node URL: " + err.Error())
+	}
+	return n
+}
+
+// ParseV4 parses a node URL.
+//
+// There are two basic forms of node URLs:
+//
+//   - 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 ParseV4(rawurl string) (*Node, error) {
+	if m := incompleteNodeURL.FindStringSubmatch(rawurl); m != nil {
+		id, err := parsePubkey(m[1])
+		if err != nil {
+			return nil, fmt.Errorf("invalid node ID (%v)", err)
+		}
+		return NewV4(id, nil, 0, 0), nil
+	}
+	return parseComplete(rawurl)
+}
+
+// NewV4 creates a node from discovery v4 node information. The record
+// contained in the node has a zero-length signature.
+func NewV4(pubkey *ecdsa.PublicKey, ip net.IP, tcp, udp int) *Node {
+	var r enr.Record
+	if ip != nil {
+		r.Set(enr.IP(ip))
+	}
+	if udp != 0 {
+		r.Set(enr.UDP(udp))
+	}
+	if tcp != 0 {
+		r.Set(enr.TCP(tcp))
+	}
+	signV4Compat(&r, pubkey)
+	n, err := New(v4CompatID{}, &r)
+	if err != nil {
+		panic(err)
+	}
+	return n
+}
+
+func parseComplete(rawurl string) (*Node, error) {
+	var (
+		id               *ecdsa.PublicKey
+		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 = parsePubkey(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 NewV4(id, ip, int(tcpPort), int(udpPort)), nil
+}
+
+// parsePubkey parses a hex-encoded secp256k1 public key.
+func parsePubkey(in string) (*ecdsa.PublicKey, error) {
+	b, err := hex.DecodeString(in)
+	if err != nil {
+		return nil, err
+	} else if len(b) != 64 {
+		return nil, fmt.Errorf("wrong length, want %d hex chars", 128)
+	}
+	b = append([]byte{0x4}, b...)
+	return crypto.UnmarshalPubkey(b)
+}
+
+func (n *Node) v4URL() string {
+	var (
+		scheme enr.ID
+		nodeid string
+		key    ecdsa.PublicKey
+	)
+	n.Load(&scheme)
+	n.Load((*Secp256k1)(&key))
+	switch {
+	case scheme == "v4" || key != ecdsa.PublicKey{}:
+		nodeid = fmt.Sprintf("%x", crypto.FromECDSAPub(&key)[1:])
+	default:
+		nodeid = fmt.Sprintf("%s.%x", scheme, n.id[:])
+	}
+	u := url.URL{Scheme: "enode"}
+	if n.Incomplete() {
+		u.Host = nodeid
+	} else {
+		addr := net.TCPAddr{IP: n.IP(), Port: n.TCP()}
+		u.User = url.User(nodeid)
+		u.Host = addr.String()
+		if n.UDP() != n.TCP() {
+			u.RawQuery = "discport=" + strconv.Itoa(n.UDP())
+		}
+	}
+	return u.String()
+}
+
+// PubkeyToIDV4 derives the v4 node address from the given public key.
+func PubkeyToIDV4(key *ecdsa.PublicKey) ID {
+	e := make([]byte, 64)
+	math.ReadBits(key.X, e[:len(e)/2])
+	math.ReadBits(key.Y, e[len(e)/2:])
+	return ID(crypto.Keccak256Hash(e))
+}