lnwallet/chanfunding: add Inputs/Outputs to assemblers

This will be used to try to estimate how much the funding transaction
will decrease our wallet balance.

lnwallet/chanfunding/assembler.go

@@ -103,6 +103,16 @@ type Intent interface {
 	// change.
 	LocalFundingAmt() btcutil.Amount
 
+	// Inputs returns all inputs to the final funding transaction that we
+	// know about. Note that there might be more, but we are not (yet)
+	// aware of.
+	Inputs() []wire.OutPoint
+
+	// Outputs returns all outputs of the final funding transaction that we
+	// know about. Note that there might be more, but we are not (yet)
+	// aware of.
+	Outputs() []*wire.TxOut
+
 	// Cancel allows the caller to cancel a funding Intent at any time.
 	// This will return any resources such as coins back to the eligible
 	// pool to be used in order channel fundings.

lnwallet/chanfunding/canned_assembler.go

@@ -98,6 +98,30 @@ func (s *ShimIntent) ThawHeight() uint32 {
 	return s.thawHeight
 }
 
+// Inputs returns all inputs to the final funding transaction that we
+// know about. For the ShimIntent this will always be none, since it is funded
+// externally.
+func (s *ShimIntent) Inputs() []wire.OutPoint {
+	return nil
+}
+
+// Outputs returns all outputs of the final funding transaction that we
+// know about. Since this is an externally funded channel, the channel output
+// is the only known one.
+func (s *ShimIntent) Outputs() []*wire.TxOut {
+	_, txOut, err := s.FundingOutput()
+	if err != nil {
+		log.Warnf("Unable to find funding output for shim intent: %v",
+			err)
+
+		// Failed finding funding output, return empty list of known
+		// outputs.
+		return nil
+	}
+
+	return []*wire.TxOut{txOut}
+}
+
 // FundingKeys couples our multi-sig key along with the remote party's key.
 type FundingKeys struct {
 	// LocalKey is our multi-sig key.

lnwallet/chanfunding/psbt_assembler.go

@@ -392,6 +392,53 @@ func (i *PsbtIntent) Cancel() {
 	i.ShimIntent.Cancel()
 }
 
+// Inputs returns all inputs to the final funding transaction that we know
+// about. These are only known after the PSBT has been verified.
+func (i *PsbtIntent) Inputs() []wire.OutPoint {
+	var inputs []wire.OutPoint
+
+	switch i.State {
+
+	// We return the inputs to the pending psbt.
+	case PsbtVerified:
+		for _, in := range i.PendingPsbt.UnsignedTx.TxIn {
+			inputs = append(inputs, in.PreviousOutPoint)
+		}
+
+	// We return the inputs to the final funding tx.
+	case PsbtFinalized, PsbtFundingTxCompiled:
+		for _, in := range i.FinalTX.TxIn {
+			inputs = append(inputs, in.PreviousOutPoint)
+		}
+
+	// In all other states we cannot know the inputs to the funding tx, and
+	// return an empty list.
+	default:
+	}
+
+	return inputs
+}
+
+// Outputs returns all outputs of the final funding transaction that we
+// know about. These are only known after the PSBT has been verified.
+func (i *PsbtIntent) Outputs() []*wire.TxOut {
+	switch i.State {
+
+	// We return the outputs of the pending psbt.
+	case PsbtVerified:
+		return i.PendingPsbt.UnsignedTx.TxOut
+
+	// We return the outputs of the final funding tx.
+	case PsbtFinalized, PsbtFundingTxCompiled:
+		return i.FinalTX.TxOut
+
+	// In all other states we cannot know the final outputs, and return an
+	// empty list.
+	default:
+		return nil
+	}
+}
+
 // PsbtAssembler is a type of chanfunding.Assembler wherein the funding
 // transaction is constructed outside of lnd by using partially signed bitcoin
 // transactions (PSBT).

lnwallet/chanfunding/wallet_assembler.go

@@ -152,6 +152,28 @@ func (f *FullIntent) CompileFundingTx(extraInputs []*wire.TxIn,
 	return fundingTx, nil
 }
 
+// Inputs returns all inputs to the final funding transaction that we
+// know about. Since this funding transaction is created all from our wallet,
+// it will be all inputs.
+func (f *FullIntent) Inputs() []wire.OutPoint {
+	var ins []wire.OutPoint
+	for _, coin := range f.InputCoins {
+		ins = append(ins, coin.OutPoint)
+	}
+
+	return ins
+}
+
+// Outputs returns all outputs of the final funding transaction that we
+// know about. This will be the funding output and the change outputs going
+// back to our wallet.
+func (f *FullIntent) Outputs() []*wire.TxOut {
+	outs := f.ShimIntent.Outputs()
+	outs = append(outs, f.ChangeOutputs...)
+
+	return outs
+}
+
 // Cancel allows the caller to cancel a funding Intent at any time.  This will
 // return any resources such as coins back to the eligible pool to be used in
 // order channel fundings.