rpcserver: implement PSBT funding flow
A PSBT funding flow consists of multiple steps. We add new RPC messages that can trigger the underlying state machine to transition to a new state. We also add new response messages that tell the API user what the current state is.
This commit is contained in:
Oliver Gugger
parent
5a52420ab6
commit
376a747bb2
134
rpcserver.go
134
rpcserver.go
@ -19,10 +19,12 @@ import (
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"github.com/btcsuite/btcd/blockchain"
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"github.com/btcsuite/btcd/btcec"
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"github.com/btcsuite/btcd/chaincfg"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/btcsuite/btcutil"
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"github.com/btcsuite/btcutil/psbt"
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"github.com/btcsuite/btcwallet/wallet/txauthor"
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"github.com/davecgh/go-spew/spew"
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grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
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@ -1556,6 +1558,51 @@ func newFundingShimAssembler(chanPointShim *lnrpc.ChanPointShim, initiator bool,
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), nil
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}
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// newFundingShimAssembler returns a new fully populated
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// chanfunding.PsbtAssembler using a FundingShim obtained from an RPC caller.
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func newPsbtAssembler(req *lnrpc.OpenChannelRequest, normalizedMinConfs int32,
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psbtShim *lnrpc.PsbtShim, netParams *chaincfg.Params) (
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chanfunding.Assembler, error) {
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var (
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packet *psbt.Packet
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err error
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)
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// Perform some basic sanity checks to ensure that all the expected
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// fields are populated and none of the incompatible fields are.
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if len(psbtShim.PendingChanId) != 32 {
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return nil, fmt.Errorf("pending chan ID not set")
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}
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if normalizedMinConfs != 1 {
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return nil, fmt.Errorf("setting non-default values for " +
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"minimum confirmation is not supported for PSBT " +
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"funding")
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}
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if req.SatPerByte != 0 || req.TargetConf != 0 {
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return nil, fmt.Errorf("specifying fee estimation parameters " +
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"is not supported for PSBT funding")
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}
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// The base PSBT is optional. But if it's set, it has to be a valid,
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// binary serialized PSBT.
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if len(psbtShim.BasePsbt) > 0 {
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packet, err = psbt.NewFromRawBytes(
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bytes.NewReader(psbtShim.BasePsbt), false,
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)
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if err != nil {
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return nil, fmt.Errorf("error parsing base PSBT: %v",
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err)
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}
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}
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// With all the parts assembled, we can now make the canned assembler
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// to pass into the wallet.
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return chanfunding.NewPsbtAssembler(
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btcutil.Amount(req.LocalFundingAmount), packet, netParams,
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), nil
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}
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// OpenChannel attempts to open a singly funded channel specified in the
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// request to a remote peer.
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func (r *rpcServer) OpenChannel(in *lnrpc.OpenChannelRequest,
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@ -1675,10 +1722,11 @@ func (r *rpcServer) OpenChannel(in *lnrpc.OpenChannelRequest,
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// If the user has provided a shim, then we'll now augment the based
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// open channel request with this additional logic.
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if in.FundingShim != nil {
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switch {
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// If we have a chan point shim, then this means the funding
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// transaction was crafted externally. In this case we only
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// need to hand a channel point down into the wallet.
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if in.FundingShim.GetChanPointShim() != nil {
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case in.FundingShim.GetChanPointShim() != nil:
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chanPointShim := in.FundingShim.GetChanPointShim()
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// Map the channel point shim into a new
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@ -1691,6 +1739,25 @@ func (r *rpcServer) OpenChannel(in *lnrpc.OpenChannelRequest,
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if err != nil {
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return err
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}
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// If we have a PSBT shim, then this means the funding
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// transaction will be crafted outside of the wallet, once the
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// funding multisig output script is known. We'll create an
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// intent that will supervise the multi-step process.
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case in.FundingShim.GetPsbtShim() != nil:
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psbtShim := in.FundingShim.GetPsbtShim()
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// Instruct the wallet to use the new
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// chanfunding.PsbtAssembler to construct the funding
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// transaction.
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copy(req.pendingChanID[:], psbtShim.PendingChanId)
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req.chanFunder, err = newPsbtAssembler(
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in, minConfs, psbtShim,
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&r.server.cc.wallet.Cfg.NetParams,
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)
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if err != nil {
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return err
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}
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}
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}
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@ -6236,6 +6303,7 @@ func (r *rpcServer) BakeMacaroon(ctx context.Context,
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func (r *rpcServer) FundingStateStep(ctx context.Context,
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in *lnrpc.FundingTransitionMsg) (*lnrpc.FundingStateStepResp, error) {
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var pendingChanID [32]byte
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switch {
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// If this is a message to register a new shim that is an external
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@ -6269,7 +6337,6 @@ func (r *rpcServer) FundingStateStep(ctx context.Context,
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// Once we receive an incoming funding request that uses this
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// pending channel ID, then this shim will be dispatched in
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// place of our regular funding workflow.
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var pendingChanID [32]byte
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copy(pendingChanID[:], rpcShimIntent.PendingChanId)
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err = r.server.cc.wallet.RegisterFundingIntent(
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pendingChanID, shimIntent,
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@ -6278,18 +6345,71 @@ func (r *rpcServer) FundingStateStep(ctx context.Context,
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return nil, err
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}
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// There is no need to register a PSBT shim before opening the channel,
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// even though our RPC message structure allows for it. Inform the user
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// by returning a proper error instead of just doing nothing.
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case in.GetShimRegister() != nil &&
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in.GetShimRegister().GetPsbtShim() != nil:
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return nil, fmt.Errorf("PSBT shim must only be sent when " +
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"opening a channel")
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// If this is a transition to cancel an existing shim, then we'll pass
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// this message along to the wallet.
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// this message along to the wallet, informing it that the intent no
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// longer needs to be considered and should be cleaned up.
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case in.GetShimCancel() != nil:
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pid := in.GetShimCancel().PendingChanId
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var pendingChanID [32]byte
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copy(pendingChanID[:], pid)
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rpcsLog.Debugf("Canceling funding shim for pending_id=%x",
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in.GetShimCancel().PendingChanId)
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copy(pendingChanID[:], in.GetShimCancel().PendingChanId)
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err := r.server.cc.wallet.CancelFundingIntent(pendingChanID)
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if err != nil {
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return nil, err
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}
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// If this is a transition to verify the PSBT for an existing shim,
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// we'll do so and then store the verified PSBT for later so we can
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// compare it to the final, signed one.
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case in.GetPsbtVerify() != nil:
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rpcsLog.Debugf("Verifying PSBT for pending_id=%x",
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in.GetPsbtVerify().PendingChanId)
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copy(pendingChanID[:], in.GetPsbtVerify().PendingChanId)
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packet, err := psbt.NewFromRawBytes(
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bytes.NewReader(in.GetPsbtVerify().FundedPsbt), false,
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)
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if err != nil {
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return nil, fmt.Errorf("error parsing psbt: %v", err)
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}
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err = r.server.cc.wallet.PsbtFundingVerify(
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pendingChanID, packet,
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)
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if err != nil {
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return nil, err
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}
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// If this is a transition to finalize the PSBT funding flow, we compare
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// the final PSBT to the previously verified one and if nothing
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// unexpected was changed, continue the channel opening process.
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case in.GetPsbtFinalize() != nil:
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rpcsLog.Debugf("Finalizing PSBT for pending_id=%x",
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in.GetPsbtFinalize().PendingChanId)
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copy(pendingChanID[:], in.GetPsbtFinalize().PendingChanId)
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packet, err := psbt.NewFromRawBytes(
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bytes.NewReader(in.GetPsbtFinalize().SignedPsbt), false,
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)
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if err != nil {
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return nil, fmt.Errorf("error parsing psbt: %v", err)
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}
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err = r.server.cc.wallet.PsbtFundingFinalize(
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pendingChanID, packet,
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)
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if err != nil {
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return nil, err
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}
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}
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// TODO(roasbeef): extend PendingChannels to also show shims
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