SPV Support

[matheusd]

Issue to track the changes needed for SPV support

• cfilterV2/blockcf2 support in dcrwallet (Switch to cfiltersv2 dcrwallet#1648)
• Create a dcrwalletnotify driver for chainntnfs such that it can use cfiltersV2 to perform the chain watching capabilities (fulfill the chainntnfs.ChainNotifier interface)
  • Create chainscan that uses cfiltersv2 to scan for confirmation/spends (Add Chainscan package #83)
  • Possibly work in solution for Verify chainntfs in case of disapproved blocks #69
  • Create appropriate APIs in the wallet to allow fetching cfiltersV2 and blocks in embedded and remote wallet modes (rpc: Add GetRawBlocks and GetCFilters gRPC methods  dcrwallet#1705)
• Use dcrwalletnotify even in RPC mode (blockheader committed filters allow that without loss of security - assumes dcp0005 passes); this allows unifying into a single code path independent of the node's mode of operation (rpc/spv) (Add wallet-backed chainntnfs implementations #92, Add wallet-backed chainview drivers #93)
• Create an WalletChainIO to fulfill lnwallet.BlockChainIO interface
  • (only GetUtxo() is potentially faster in rpc mode vs spv so for the most part deprecate RPChainIO and use WalletChainIO even in rpc mode (Switch to wallet-backed chain io in dcrlnd #94)
• Test SPV mode when running in remote wallet mode (Enable and test SPV mode for remote wallets #95)
• Add SPV mode for embedded wallet mode (Multi: Support SPV in embedded wallet mode #140)

[matheusd]

SPV is fully supported.