multi: add channel open parameters to channel acceptor

Add more fields to channel acceptor response so that users can have more
fine grained control over their incoming channels. With our chained
acceptor, it is possible that we get inconsistent responses from
multiple chained acceptors. We create a conjugate repsponse from all the
set fields in our various responses, but fail if we get different, non-
zero responses from our various acceptors. Separate merge functions are
used per type so that we avoid unexpected outcomes comparing interfaces
(panic on comparing types that aren't comparable), with casting used
where applicable to avoid code duplication.

chanacceptor/merge_test.go

@@ -0,0 +1,188 @@
+package chanacceptor
+
+import (
+	"testing"
+
+	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/stretchr/testify/require"
+)
+
+// TestMergeResponse tests merging of channel acceptor responses.
+func TestMergeResponse(t *testing.T) {
+	var (
+		addr1 = lnwire.DeliveryAddress{1}
+		addr2 = lnwire.DeliveryAddress{2}
+
+		populatedResp = ChannelAcceptResponse{
+			UpfrontShutdown: addr1,
+			CSVDelay:        2,
+			Reserve:         3,
+			InFlightTotal:   4,
+			HtlcLimit:       5,
+			MinHtlcIn:       6,
+			MinAcceptDepth:  7,
+		}
+	)
+
+	tests := []struct {
+		name    string
+		current ChannelAcceptResponse
+		new     ChannelAcceptResponse
+		merged  ChannelAcceptResponse
+		err     error
+	}{
+		{
+			name:    "same response",
+			current: populatedResp,
+			new:     populatedResp,
+			merged:  populatedResp,
+			err:     nil,
+		},
+		{
+			name: "different upfront",
+			current: ChannelAcceptResponse{
+				UpfrontShutdown: addr1,
+			},
+			new: ChannelAcceptResponse{
+				UpfrontShutdown: addr2,
+			},
+			err: fieldMismatchError(fieldUpfrontShutdown, addr1, addr2),
+		},
+		{
+			name: "different csv",
+			current: ChannelAcceptResponse{
+				CSVDelay: 1,
+			},
+			new: ChannelAcceptResponse{
+				CSVDelay: 2,
+			},
+			err: fieldMismatchError(fieldCSV, 1, 2),
+		},
+		{
+			name: "different reserve",
+			current: ChannelAcceptResponse{
+				Reserve: 1,
+			},
+			new: ChannelAcceptResponse{
+				Reserve: 2,
+			},
+			err: fieldMismatchError(fieldReserve, 1, 2),
+		},
+		{
+			name: "different in flight",
+			current: ChannelAcceptResponse{
+				InFlightTotal: 1,
+			},
+			new: ChannelAcceptResponse{
+				InFlightTotal: 2,
+			},
+			err: fieldMismatchError(
+				fieldInFlightTotal, lnwire.MilliSatoshi(1),
+				lnwire.MilliSatoshi(2),
+			),
+		},
+		{
+			name: "different htlc limit",
+			current: ChannelAcceptResponse{
+				HtlcLimit: 1,
+			},
+			new: ChannelAcceptResponse{
+				HtlcLimit: 2,
+			},
+			err: fieldMismatchError(fieldHtlcLimit, 1, 2),
+		},
+		{
+			name: "different min in",
+			current: ChannelAcceptResponse{
+				MinHtlcIn: 1,
+			},
+			new: ChannelAcceptResponse{
+				MinHtlcIn: 2,
+			},
+			err: fieldMismatchError(
+				fieldMinIn, lnwire.MilliSatoshi(1),
+				lnwire.MilliSatoshi(2),
+			),
+		},
+		{
+			name: "different depth",
+			current: ChannelAcceptResponse{
+				MinAcceptDepth: 1,
+			},
+			new: ChannelAcceptResponse{
+				MinAcceptDepth: 2,
+			},
+			err: fieldMismatchError(fieldMinDep, 1, 2),
+		},
+		{
+			name: "merge all values",
+			current: ChannelAcceptResponse{
+				UpfrontShutdown: lnwire.DeliveryAddress{1},
+				CSVDelay:        1,
+				Reserve:         0,
+				InFlightTotal:   3,
+				HtlcLimit:       0,
+				MinHtlcIn:       5,
+				MinAcceptDepth:  0,
+			},
+			new: ChannelAcceptResponse{
+				UpfrontShutdown: nil,
+				CSVDelay:        0,
+				Reserve:         2,
+				InFlightTotal:   0,
+				HtlcLimit:       4,
+				MinHtlcIn:       0,
+				MinAcceptDepth:  6,
+			},
+			merged: ChannelAcceptResponse{
+				UpfrontShutdown: lnwire.DeliveryAddress{1},
+				CSVDelay:        1,
+				Reserve:         2,
+				InFlightTotal:   3,
+				HtlcLimit:       4,
+				MinHtlcIn:       5,
+				MinAcceptDepth:  6,
+			},
+			err: nil,
+		},
+		{
+			// Test the case where fields have the same non-zero
+			// value, and the case where only response value is
+			// non-zero.
+			name: "empty and identical",
+			current: ChannelAcceptResponse{
+				CSVDelay:      1,
+				Reserve:       2,
+				InFlightTotal: 0,
+			},
+			new: ChannelAcceptResponse{
+				CSVDelay:      0,
+				Reserve:       2,
+				InFlightTotal: 3,
+			},
+			merged: ChannelAcceptResponse{
+				CSVDelay:      1,
+				Reserve:       2,
+				InFlightTotal: 3,
+			},
+			err: nil,
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+
+		t.Run(test.name, func(t *testing.T) {
+			resp, err := mergeResponse(test.current, test.new)
+			require.Equal(t, test.err, err)
+
+			// If we expect an error, exit early rather than compare
+			// our result.
+			if test.err != nil {
+				return
+			}
+
+			require.Equal(t, test.merged, resp)
+		})
+	}
+}