htlcswitch+router: add onion error obfuscation

Within the network, it's important that when an HTLC forwarding failure
occurs, the recipient is notified in a timely manner in order to ensure
that errors are graceful and not unknown. For that reason with
accordance to BOLT №4 onion failure obfuscation have been added.

htlcswitch/link_test.go

@@ -376,10 +376,10 @@ func TestExitNodeTimelockPayloadMismatch(t *testing.T) {
 		n.bobServer.PubKey(), hops, amount, htlcAmt, htlcExpiry)
 	if err == nil {
 		t.Fatalf("payment should have failed but didn't")
-	} else if err.Error() != lnwire.UpstreamTimeout.String() {
+	} else if err.Error() != lnwire.CodeFinalIncorrectCltvExpiry.String() {
 		// TODO(roasbeef): use proper error after error propagation is
 		// in
-		t.Fatalf("incorrect error, expected insufficient value, "+
+		t.Fatalf("incorrect error, expected incorrect cltv expiry, "+
 			"instead have: %v", err)
 	}
 }
@@ -413,7 +413,7 @@ func TestExitNodeAmountPayloadMismatch(t *testing.T) {
 		n.bobServer.PubKey(), hops, amount, htlcAmt, htlcExpiry)
 	if err == nil {
 		t.Fatalf("payment should have failed but didn't")
-	} else if err.Error() != lnwire.IncorrectValue.String() {
+	} else if err.Error() != lnwire.CodeIncorrectPaymentAmount.String() {
 		// TODO(roasbeef): use proper error after error propagation is
 		// in
 		t.Fatalf("incorrect error, expected insufficient value, "+
@@ -455,10 +455,8 @@ func TestLinkForwardTimelockPolicyMismatch(t *testing.T) {
 	// should be rejected due to a policy violation.
 	if err == nil {
 		t.Fatalf("payment should have failed but didn't")
-	} else if err.Error() != lnwire.UpstreamTimeout.String() {
-		// TODO(roasbeef): use proper error after error propagation is
-		// in
-		t.Fatalf("incorrect error, expected insufficient value, "+
+	} else if err.Error() != lnwire.CodeIncorrectCltvExpiry.String() {
+		t.Fatalf("incorrect error, expected incorrect cltv expiry, "+
 			"instead have: %v", err)
 	}
 }
@@ -498,10 +496,10 @@ func TestLinkForwardFeePolicyMismatch(t *testing.T) {
 	// should be rejected due to a policy violation.
 	if err == nil {
 		t.Fatalf("payment should have failed but didn't")
-	} else if err.Error() != lnwire.IncorrectValue.String() {
+	} else if err.Error() != lnwire.CodeFeeInsufficient.String() {
 		// TODO(roasbeef): use proper error after error propagation is
 		// in
-		t.Fatalf("incorrect error, expected insufficient value, "+
+		t.Fatalf("incorrect error, expected fee insufficient, "+
 			"instead have: %v", err)
 	}
 }
@@ -541,10 +539,10 @@ func TestLinkForwardMinHTLCPolicyMismatch(t *testing.T) {
 	// should be rejected due to a policy violation (below min HTLC).
 	if err == nil {
 		t.Fatalf("payment should have failed but didn't")
-	} else if err.Error() != lnwire.IncorrectValue.String() {
+	} else if err.Error() != lnwire.CodeAmountBelowMinimum.String() {
 		// TODO(roasbeef): use proper error after error propagation is
 		// in
-		t.Fatalf("incorrect error, expected insufficient value, "+
+		t.Fatalf("incorrect error, expected amount below minimum, "+
 			"instead have: %v", err)
 	}
 }
@@ -633,7 +631,7 @@ func TestChannelLinkMultiHopInsufficientPayment(t *testing.T) {
 		btcutil.SatoshiPerBitcoin*5,
 	)
 	if err := n.start(); err != nil {
-		t.Fatalf("can't start three hop network: %v", err)
+		t.Fatalf("unable to start three hop network: %v", err)
 	}
 	defer n.stop()
 
@@ -656,7 +654,7 @@ func TestChannelLinkMultiHopInsufficientPayment(t *testing.T) {
 		n.bobServer.PubKey(), hops, amount, htlcAmt, totalTimelock)
 	if err == nil {
 		t.Fatal("error haven't been received")
-	} else if err.Error() != errors.New(lnwire.InsufficientCapacity).Error() {
+	} else if err.Error() != errors.New(lnwire.CodeTemporaryChannelFailure).Error() {
 		t.Fatalf("wrong error have been received: %v", err)
 	}
 
@@ -702,7 +700,7 @@ func TestChannelLinkMultiHopUnknownPaymentHash(t *testing.T) {
 		btcutil.SatoshiPerBitcoin*5,
 	)
 	if err := n.start(); err != nil {
-		t.Fatalf("can't start three hop network: %v", err)
+		t.Fatalf("unable to start three hop network: %v", err)
 	}
 	defer n.stop()
 
@@ -733,13 +731,14 @@ func TestChannelLinkMultiHopUnknownPaymentHash(t *testing.T) {
 
 	// Check who is last in the route and add invoice to server registry.
 	if err := n.carolServer.registry.AddInvoice(invoice); err != nil {
-		t.Fatalf("can't add invoice in carol registry: %v", err)
+		t.Fatalf("unable to add invoice in carol registry: %v", err)
 	}
 
 	// Send payment and expose err channel.
-	_, err = n.aliceServer.htlcSwitch.SendHTLC(n.bobServer.PubKey(), htlc)
-	if err == nil {
-		t.Fatal("error wasn't received")
+	_, err = n.aliceServer.htlcSwitch.SendHTLC(n.bobServer.PubKey(), htlc,
+		newMockDeobfuscator())
+	if err.Error() != lnwire.CodeUnknownPaymentHash.String() {
+		t.Fatal("error haven't been received")
 	}
 
 	// Wait for Alice to receive the revocation.
@@ -802,7 +801,7 @@ func TestChannelLinkMultiHopUnknownNextHop(t *testing.T) {
 		amount, htlcAmt, totalTimelock)
 	if err == nil {
 		t.Fatal("error haven't been received")
-	} else if err.Error() != errors.New(lnwire.UnknownDestination).Error() {
+	} else if err.Error() != lnwire.CodeUnknownNextPeer.String() {
 		t.Fatalf("wrong error have been received: %v", err)
 	}
 
@@ -848,14 +847,14 @@ func TestChannelLinkMultiHopDecodeError(t *testing.T) {
 		btcutil.SatoshiPerBitcoin*5,
 	)
 	if err := n.start(); err != nil {
-		t.Fatalf("can't start three hop network: %v", err)
+		t.Fatalf("unable to start three hop network: %v", err)
 	}
 	defer n.stop()
 
 	// Replace decode function with another which throws an error.
-	n.carolChannelLink.cfg.DecodeOnion = func(r io.Reader, meta []byte) (
-		HopIterator, error) {
-		return nil, errors.New("some sphinx decode error")
+	n.carolChannelLink.cfg.DecodeOnionObfuscator = func(
+		r io.Reader) (Obfuscator, lnwire.FailCode) {
+		return nil, lnwire.CodeInvalidOnionVersion
 	}
 
 	carolBandwidthBefore := n.carolChannelLink.Bandwidth()
@@ -871,7 +870,7 @@ func TestChannelLinkMultiHopDecodeError(t *testing.T) {
 		n.bobServer.PubKey(), hops, amount, htlcAmt, totalTimelock)
 	if err == nil {
 		t.Fatal("error haven't been received")
-	} else if err.Error() != errors.New(lnwire.SphinxParseError).Error() {
+	} else if err.Error() != lnwire.CodeInvalidOnionVersion.String() {
 		t.Fatalf("wrong error have been received: %v", err)
 	}
 
@@ -994,7 +993,7 @@ func TestChannelLinkSingleHopMessageOrdering(t *testing.T) {
 	})
 
 	if err := n.start(); err != nil {
-		t.Fatalf("can't start three hop network: %v", err)
+		t.Fatalf("unable to start three hop network: %v", err)
 	}
 	defer n.stop()