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78 lines
2.3 KiB
Go
78 lines
2.3 KiB
Go
package lnd
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import (
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/lightningnetwork/lnd/channeldb"
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"github.com/lightningnetwork/lnd/input"
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)
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type LightningChannel struct {
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LocalChanCfg channeldb.ChannelConfig
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RemoteChanCfg channeldb.ChannelConfig
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SignDesc *input.SignDescriptor
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ChannelState *channeldb.OpenChannel
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TXSigner *Signer
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}
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// CreateSignDesc derives the SignDescriptor for commitment transactions from
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// other fields on the LightningChannel.
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func (lc *LightningChannel) CreateSignDesc() error {
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localKey := lc.LocalChanCfg.MultiSigKey.PubKey.SerializeCompressed()
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remoteKey := lc.RemoteChanCfg.MultiSigKey.PubKey.SerializeCompressed()
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multiSigScript, err := input.GenMultiSigScript(localKey, remoteKey)
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if err != nil {
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return err
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}
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fundingPkScript, err := input.WitnessScriptHash(multiSigScript)
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if err != nil {
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return err
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}
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lc.SignDesc = &input.SignDescriptor{
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KeyDesc: lc.LocalChanCfg.MultiSigKey,
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WitnessScript: multiSigScript,
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Output: &wire.TxOut{
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PkScript: fundingPkScript,
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Value: int64(lc.ChannelState.Capacity),
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},
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HashType: txscript.SigHashAll,
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InputIndex: 0,
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}
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return nil
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}
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// SignedCommitTx function take the latest commitment transaction and populate
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// it with witness data.
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func (lc *LightningChannel) SignedCommitTx() (*wire.MsgTx, error) {
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// Fetch the current commitment transaction, along with their signature
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// for the transaction.
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localCommit := lc.ChannelState.LocalCommitment
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commitTx := localCommit.CommitTx.Copy()
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theirSig := append(localCommit.CommitSig, byte(txscript.SigHashAll))
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// With this, we then generate the full witness so the caller can
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// broadcast a fully signed transaction.
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lc.SignDesc.SigHashes = txscript.NewTxSigHashes(commitTx)
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ourSigRaw, err := lc.TXSigner.SignOutputRaw(commitTx, lc.SignDesc)
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if err != nil {
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return nil, err
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}
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ourSig := append(ourSigRaw, byte(txscript.SigHashAll))
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// With the final signature generated, create the witness stack
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// required to spend from the multi-sig output.
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ourKey := lc.LocalChanCfg.MultiSigKey.PubKey.SerializeCompressed()
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theirKey := lc.RemoteChanCfg.MultiSigKey.PubKey.SerializeCompressed()
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commitTx.TxIn[0].Witness = input.SpendMultiSig(
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lc.SignDesc.WitnessScript, ourKey,
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ourSig, theirKey, theirSig,
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)
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return commitTx, nil
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}
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