// Copyright 2020 The go-ethereum Authors // This file is part of go-ethereum. // // go-ethereum is free software: you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // // go-ethereum 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 General Public License for more details. // // You should have received a copy of the GNU General Public License // along with go-ethereum. If not, see <http://www.gnu.org/licenses/>. package v4test import ( "bytes" "crypto/rand" "errors" "fmt" "net" "time" "github.com/ethereum/go-ethereum/crypto" "github.com/ethereum/go-ethereum/internal/utesting" "github.com/ethereum/go-ethereum/p2p/discover/v4wire" ) const ( expiration = 20 * time.Second wrongPacket = 66 macSize = 256 / 8 ) var ( // Remote node under test Remote string // Listen1 is the IP where the first tester is listening, port will be assigned Listen1 string = "127.0.0.1" // Listen2 is the IP where the second tester is listening, port will be assigned // Before running the test, you may have to `sudo ifconfig lo0 add 127.0.0.2` (on MacOS at least) Listen2 string = "127.0.0.2" ) type pingWithJunk struct { Version uint From, To v4wire.Endpoint Expiration uint64 JunkData1 uint JunkData2 []byte } func (req *pingWithJunk) Name() string { return "PING/v4" } func (req *pingWithJunk) Kind() byte { return v4wire.PingPacket } type pingWrongType struct { Version uint From, To v4wire.Endpoint Expiration uint64 } func (req *pingWrongType) Name() string { return "WRONG/v4" } func (req *pingWrongType) Kind() byte { return wrongPacket } func futureExpiration() uint64 { return uint64(time.Now().Add(expiration).Unix()) } // BasicPing just sends a PING packet and expects a response. func BasicPing(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() pingHash := te.send(te.l1, &v4wire.Ping{ Version: 4, From: te.localEndpoint(te.l1), To: te.remoteEndpoint(), Expiration: futureExpiration(), }) if err := te.checkPingPong(pingHash); err != nil { t.Fatal(err) } } // checkPingPong verifies that the remote side sends both a PONG with the // correct hash, and a PING. // The two packets do not have to be in any particular order. func (te *testenv) checkPingPong(pingHash []byte) error { var ( pings int pongs int ) for i := 0; i < 2; i++ { reply, _, err := te.read(te.l1) if err != nil { return err } switch reply.Kind() { case v4wire.PongPacket: if err := te.checkPong(reply, pingHash); err != nil { return err } pongs++ case v4wire.PingPacket: pings++ default: return fmt.Errorf("expected PING or PONG, got %v %v", reply.Name(), reply) } } if pongs == 1 && pings == 1 { return nil } return fmt.Errorf("expected 1 PING (got %d) and 1 PONG (got %d)", pings, pongs) } // checkPong verifies that reply is a valid PONG matching the given ping hash, // and a PING. The two packets do not have to be in any particular order. func (te *testenv) checkPong(reply v4wire.Packet, pingHash []byte) error { if reply == nil { return errors.New("expected PONG reply, got nil") } if reply.Kind() != v4wire.PongPacket { return fmt.Errorf("expected PONG reply, got %v %v", reply.Name(), reply) } pong := reply.(*v4wire.Pong) if !bytes.Equal(pong.ReplyTok, pingHash) { return fmt.Errorf("PONG reply token mismatch: got %x, want %x", pong.ReplyTok, pingHash) } if want := te.localEndpoint(te.l1); !want.IP.Equal(pong.To.IP) || want.UDP != pong.To.UDP { return fmt.Errorf("PONG 'to' endpoint mismatch: got %+v, want %+v", pong.To, want) } if v4wire.Expired(pong.Expiration) { return fmt.Errorf("PONG is expired (%v)", pong.Expiration) } return nil } // PingWrongTo sends a PING packet with wrong 'to' field and expects a PONG response. func PingWrongTo(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() wrongEndpoint := v4wire.Endpoint{IP: net.ParseIP("192.0.2.0")} pingHash := te.send(te.l1, &v4wire.Ping{ Version: 4, From: te.localEndpoint(te.l1), To: wrongEndpoint, Expiration: futureExpiration(), }) if err := te.checkPingPong(pingHash); err != nil { t.Fatal(err) } } // PingWrongFrom sends a PING packet with wrong 'from' field and expects a PONG response. func PingWrongFrom(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() wrongEndpoint := v4wire.Endpoint{IP: net.ParseIP("192.0.2.0")} pingHash := te.send(te.l1, &v4wire.Ping{ Version: 4, From: wrongEndpoint, To: te.remoteEndpoint(), Expiration: futureExpiration(), }) if err := te.checkPingPong(pingHash); err != nil { t.Fatal(err) } } // PingExtraData This test sends a PING packet with additional data at the end and expects a PONG // response. The remote node should respond because EIP-8 mandates ignoring additional // trailing data. func PingExtraData(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() pingHash := te.send(te.l1, &pingWithJunk{ Version: 4, From: te.localEndpoint(te.l1), To: te.remoteEndpoint(), Expiration: futureExpiration(), JunkData1: 42, JunkData2: []byte{9, 8, 7, 6, 5, 4, 3, 2, 1}, }) if err := te.checkPingPong(pingHash); err != nil { t.Fatal(err) } } // This test sends a PING packet with additional data and wrong 'from' field // and expects a PONG response. func PingExtraDataWrongFrom(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() wrongEndpoint := v4wire.Endpoint{IP: net.ParseIP("192.0.2.0")} req := pingWithJunk{ Version: 4, From: wrongEndpoint, To: te.remoteEndpoint(), Expiration: futureExpiration(), JunkData1: 42, JunkData2: []byte{9, 8, 7, 6, 5, 4, 3, 2, 1}, } pingHash := te.send(te.l1, &req) if err := te.checkPingPong(pingHash); err != nil { t.Fatal(err) } } // This test sends a PING packet with an expiration in the past. // The remote node should not respond. func PingPastExpiration(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() te.send(te.l1, &v4wire.Ping{ Version: 4, From: te.localEndpoint(te.l1), To: te.remoteEndpoint(), Expiration: -futureExpiration(), }) reply, _, _ := te.read(te.l1) if reply != nil { t.Fatalf("Expected no reply, got %v %v", reply.Name(), reply) } } // This test sends an invalid packet. The remote node should not respond. func WrongPacketType(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() te.send(te.l1, &pingWrongType{ Version: 4, From: te.localEndpoint(te.l1), To: te.remoteEndpoint(), Expiration: futureExpiration(), }) reply, _, _ := te.read(te.l1) if reply != nil { t.Fatalf("Expected no reply, got %v %v", reply.Name(), reply) } } // This test verifies that the default behaviour of ignoring 'from' fields is unaffected by // the bonding process. After bonding, it pings the target with a different from endpoint. func BondThenPingWithWrongFrom(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() bond(t, te) wrongEndpoint := v4wire.Endpoint{IP: net.ParseIP("192.0.2.0")} pingHash := te.send(te.l1, &v4wire.Ping{ Version: 4, From: wrongEndpoint, To: te.remoteEndpoint(), Expiration: futureExpiration(), }) waitForPong: for { reply, _, err := te.read(te.l1) if err != nil { t.Fatal(err) } switch reply.Kind() { case v4wire.PongPacket: if err := te.checkPong(reply, pingHash); err != nil { t.Fatal(err) } break waitForPong case v4wire.FindnodePacket: // FINDNODE from the node is acceptable here since the endpoint // verification was performed earlier. default: t.Fatalf("Expected PONG, got %v %v", reply.Name(), reply) } } } // This test just sends FINDNODE. The remote node should not reply // because the endpoint proof has not completed. func FindnodeWithoutEndpointProof(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() req := v4wire.Findnode{Expiration: futureExpiration()} rand.Read(req.Target[:]) te.send(te.l1, &req) for { reply, _, _ := te.read(te.l1) if reply == nil { // No response, all good break } if reply.Kind() == v4wire.PingPacket { continue // A ping is ok, just ignore it } t.Fatalf("Expected no reply, got %v %v", reply.Name(), reply) } } // BasicFindnode sends a FINDNODE request after performing the endpoint // proof. The remote node should respond. func BasicFindnode(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() bond(t, te) findnode := v4wire.Findnode{Expiration: futureExpiration()} rand.Read(findnode.Target[:]) te.send(te.l1, &findnode) reply, _, err := te.read(te.l1) if err != nil { t.Fatal("read find nodes", err) } if reply.Kind() != v4wire.NeighborsPacket { t.Fatalf("Expected neighbors, got %v %v", reply.Name(), reply) } } // This test sends an unsolicited NEIGHBORS packet after the endpoint proof, then sends // FINDNODE to read the remote table. The remote node should not return the node contained // in the unsolicited NEIGHBORS packet. func UnsolicitedNeighbors(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() bond(t, te) // Send unsolicited NEIGHBORS response. fakeKey, _ := crypto.GenerateKey() encFakeKey := v4wire.EncodePubkey(&fakeKey.PublicKey) neighbors := v4wire.Neighbors{ Expiration: futureExpiration(), Nodes: []v4wire.Node{{ ID: encFakeKey, IP: net.IP{1, 2, 3, 4}, UDP: 30303, TCP: 30303, }}, } te.send(te.l1, &neighbors) // Check if the remote node included the fake node. te.send(te.l1, &v4wire.Findnode{ Expiration: futureExpiration(), Target: encFakeKey, }) reply, _, err := te.read(te.l1) if err != nil { t.Fatal("read find nodes", err) } if reply.Kind() != v4wire.NeighborsPacket { t.Fatalf("Expected neighbors, got %v %v", reply.Name(), reply) } nodes := reply.(*v4wire.Neighbors).Nodes if contains(nodes, encFakeKey) { t.Fatal("neighbors response contains node from earlier unsolicited neighbors response") } } // This test sends FINDNODE with an expiration timestamp in the past. // The remote node should not respond. func FindnodePastExpiration(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() bond(t, te) findnode := v4wire.Findnode{Expiration: -futureExpiration()} rand.Read(findnode.Target[:]) te.send(te.l1, &findnode) for { reply, _, _ := te.read(te.l1) if reply == nil { return } else if reply.Kind() == v4wire.NeighborsPacket { t.Fatal("Unexpected NEIGHBORS response for expired FINDNODE request") } } } // bond performs the endpoint proof with the remote node. func bond(t *utesting.T, te *testenv) { pingHash := te.send(te.l1, &v4wire.Ping{ Version: 4, From: te.localEndpoint(te.l1), To: te.remoteEndpoint(), Expiration: futureExpiration(), }) var gotPing, gotPong bool for !gotPing || !gotPong { req, hash, err := te.read(te.l1) if err != nil { t.Fatal(err) } switch req.(type) { case *v4wire.Ping: te.send(te.l1, &v4wire.Pong{ To: te.remoteEndpoint(), ReplyTok: hash, Expiration: futureExpiration(), }) gotPing = true case *v4wire.Pong: if err := te.checkPong(req, pingHash); err != nil { t.Fatal(err) } gotPong = true } } } // This test attempts to perform a traffic amplification attack against a // 'victim' endpoint using FINDNODE. In this attack scenario, the attacker // attempts to complete the endpoint proof non-interactively by sending a PONG // with mismatching reply token from the 'victim' endpoint. The attack works if // the remote node does not verify the PONG reply token field correctly. The // attacker could then perform traffic amplification by sending many FINDNODE // requests to the discovery node, which would reply to the 'victim' address. func FindnodeAmplificationInvalidPongHash(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() // Send PING to start endpoint verification. te.send(te.l1, &v4wire.Ping{ Version: 4, From: te.localEndpoint(te.l1), To: te.remoteEndpoint(), Expiration: futureExpiration(), }) var gotPing, gotPong bool for !gotPing || !gotPong { req, _, err := te.read(te.l1) if err != nil { t.Fatal(err) } switch req.(type) { case *v4wire.Ping: // Send PONG from this node ID, but with invalid ReplyTok. te.send(te.l1, &v4wire.Pong{ To: te.remoteEndpoint(), ReplyTok: make([]byte, macSize), Expiration: futureExpiration(), }) gotPing = true case *v4wire.Pong: gotPong = true } } // Now send FINDNODE. The remote node should not respond because our // PONG did not reference the PING hash. findnode := v4wire.Findnode{Expiration: futureExpiration()} rand.Read(findnode.Target[:]) te.send(te.l1, &findnode) // If we receive a NEIGHBORS response, the attack worked and the test fails. reply, _, _ := te.read(te.l1) if reply != nil && reply.Kind() == v4wire.NeighborsPacket { t.Error("Got neighbors") } } // This test attempts to perform a traffic amplification attack using FINDNODE. // The attack works if the remote node does not verify the IP address of FINDNODE // against the endpoint verification proof done by PING/PONG. func FindnodeAmplificationWrongIP(t *utesting.T) { te := newTestEnv(Remote, Listen1, Listen2) defer te.close() // Do the endpoint proof from the l1 IP. bond(t, te) // Now send FINDNODE from the same node ID, but different IP address. // The remote node should not respond. findnode := v4wire.Findnode{Expiration: futureExpiration()} rand.Read(findnode.Target[:]) te.send(te.l2, &findnode) // If we receive a NEIGHBORS response, the attack worked and the test fails. reply, _, _ := te.read(te.l2) if reply != nil { t.Error("Got NEIGHORS response for FINDNODE from wrong IP") } } var AllTests = []utesting.Test{ {Name: "Ping/Basic", Fn: BasicPing}, {Name: "Ping/WrongTo", Fn: PingWrongTo}, {Name: "Ping/WrongFrom", Fn: PingWrongFrom}, {Name: "Ping/ExtraData", Fn: PingExtraData}, {Name: "Ping/ExtraDataWrongFrom", Fn: PingExtraDataWrongFrom}, {Name: "Ping/PastExpiration", Fn: PingPastExpiration}, {Name: "Ping/WrongPacketType", Fn: WrongPacketType}, {Name: "Ping/BondThenPingWithWrongFrom", Fn: BondThenPingWithWrongFrom}, {Name: "Findnode/WithoutEndpointProof", Fn: FindnodeWithoutEndpointProof}, {Name: "Findnode/BasicFindnode", Fn: BasicFindnode}, {Name: "Findnode/UnsolicitedNeighbors", Fn: UnsolicitedNeighbors}, {Name: "Findnode/PastExpiration", Fn: FindnodePastExpiration}, {Name: "Amplification/InvalidPongHash", Fn: FindnodeAmplificationInvalidPongHash}, {Name: "Amplification/WrongIP", Fn: FindnodeAmplificationWrongIP}, }