sweep: account for all script types in craftSweepTx

With this change, transactions created via craftSweepTx will be
standard. Previously, p2wsh/p2pkh scripts passed in via SendCoins would
be weighted as p2wpkh scripts. With a feerate of 1 sat/vbyte,
transactions returned would be non-standard. Luckily, the critical
sweeper subsystem only used p2wpkh scripts so this only affected
callers from the rpcserver.

Also added is an integration test that fails if SendCoins manages
to generate a non-standard transaction. All script types are now
accounted for in getWeightEstimate, which now errors if an unknown
script type is passed in.

sweep/txgenerator_test.go

@@ -6,6 +6,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/input"
+	"github.com/stretchr/testify/require"
 )
 
 var (
@@ -39,7 +40,19 @@ func TestWeightEstimate(t *testing.T) {
 		))
 	}
 
-	_, estimator := getWeightEstimate(inputs, nil, 0, nil)
+	// Create a sweep script that is always fed into the weight estimator,
+	// regardless if it's actually included in the tx. It will be a P2WKH
+	// script.
+	changePkScript := []byte{
+		0x00, 0x14,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00,
+	}
+
+	_, estimator, err := getWeightEstimate(inputs, nil, 0, changePkScript)
+	require.NoError(t, err)
+
 	weight := int64(estimator.weight())
 	if weight != expectedWeight {
 		t.Fatalf("unexpected weight. expected %d but got %d.",
@@ -51,3 +64,97 @@ func TestWeightEstimate(t *testing.T) {
 			expectedSummary, summary)
 	}
 }
+
+// TestWeightEstimatorUnknownScript tests that the weight estimator fails when
+// given an unknown script and succeeds when given a known script.
+func TestWeightEstimatorUnknownScript(t *testing.T) {
+	tests := []struct {
+		name       string
+		pkscript   []byte
+		expectFail bool
+	}{
+		{
+			name: "p2tr output",
+			pkscript: []byte{
+				0x51, 0x20,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			},
+		},
+		{
+			name: "p2wsh output",
+			pkscript: []byte{
+				0x00, 0x20,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			},
+		},
+		{
+			name: "p2wkh output",
+			pkscript: []byte{
+				0x00, 0x14,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00,
+			},
+		},
+		{
+			name: "p2pkh output",
+			pkscript: []byte{
+				0x76, 0xa9, 0x14,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00,
+				0x88, 0xac,
+			},
+		},
+		{
+			name: "p2sh output",
+			pkscript: []byte{
+				0xa9, 0x14,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+				0x00, 0x00, 0x00, 0x00,
+				0x87,
+			},
+		},
+		{
+			name:       "unknown script",
+			pkscript:   []byte{0x00},
+			expectFail: true,
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.name, func(t *testing.T) {
+			testUnknownScriptInner(
+				t, test.pkscript, test.expectFail,
+			)
+		})
+	}
+}
+
+func testUnknownScriptInner(t *testing.T, pkscript []byte, expectFail bool) {
+	var inputs []input.Input
+	for i, witnessType := range witnessTypes {
+		inputs = append(inputs, input.NewBaseInput(
+			&wire.OutPoint{
+				Hash:  chainhash.Hash{byte(i)},
+				Index: uint32(i) + 10,
+			}, witnessType,
+			&input.SignDescriptor{}, 0,
+		))
+	}
+
+	_, _, err := getWeightEstimate(inputs, nil, 0, pkscript)
+	if expectFail {
+		require.Error(t, err)
+	} else {
+		require.NoError(t, err)
+	}
+}