swarm/network: Use actual remote peer ip in underlay (#19137)

* swarm/network: Logline to see handshake addr

* swarm/network: Replace remote ip in handshake uaddr

* swarm/network: Add test for enode uaddr rewrite method

* swarm/network: Remove redundance pointer return from sanitize

* swarm/network: Obeying the linting machine

* swarm/network: Add panic comment

(travis trigger take 1)

swarm/network/protocol_test.go

@@ -17,12 +17,15 @@
 package network
 
 import (
+	"bytes"
 	"flag"
 	"fmt"
+	"net"
 	"os"
 	"testing"
 	"time"
 
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/enode"
@@ -251,3 +254,26 @@ func TestBzzHandshakeLightNode(t *testing.T) {
 		})
 	}
 }
+
+// Tests the overwriting of localhost enode in handshake if actual remote ip is known
+// (swarm.network/protocol.go:sanitizeEnodeRemote)
+func TestSanitizeEnodeRemote(t *testing.T) {
+	pk, err := crypto.GenerateKey()
+	if err != nil {
+		t.Fatal(err)
+	}
+	remoteIP := net.IPv4(0x80, 0x40, 0x20, 0x10)
+	remoteAddr := net.TCPAddr{
+		IP:   remoteIP,
+		Port: 30399,
+	}
+	nodLocal := enode.NewV4(&pk.PublicKey, net.IPv4(0x7f, 0x00, 0x00, 0x01), 30341, 30341)
+	nodRemote := enode.NewV4(&pk.PublicKey, remoteIP, 30341, 30341)
+	baddr := RandomAddr()
+	oldUAddr := []byte(nodLocal.String())
+	baddr.UAddr = oldUAddr
+	sanitizeEnodeRemote(&remoteAddr, baddr)
+	if !bytes.Equal(baddr.UAddr, []byte(nodRemote.String())) {
+		t.Fatalf("insane address. expected %v, got %v", nodRemote.String(), string(baddr.UAddr))
+	}
+}