TODO

[andrewvy]

Needs

transactions

• [x] transaction_from_serialized (convert serialized protobuf into transaction struct)
• [x] verify_txin (verifies txin is valid, that it points to an unspent txout)

blocks

• [x] block_to_proto (convert block struct into proto struct)
• [x] block_to_serialized (convert block struct into serialized)
• [x] block_from_serialized (convert serialized protobuf into block struct)
• [x] add mempool (pool of verified TXs waiting to be put into block)
• [x] compute_merkle_root (computes merkle root)
• [ ] insert TXs from mempool into currently mined block
• [x] verify_merkle_root (verifies merkle root)
• [x] verify_block (verify entire block, its txin, merkle root, whole boi)

blockchain

• [x] insert_block_into_blockchain (serializes block, puts serialized block into blockchain db)
• [x] get number of blocks in the database
• [x] fetch_block_from_db (fetches block struct, deserializing from db using passed in hash)
• [x] get_block_from_tx (fetches block struct from a TX struct)
• [ ] get_block_height_for_block (gets the block height to a certain block hash, used for determining best blockchain)
• [x] remove_block_from_db
• [ ] undo_block (must go through blocks if new branch is valid, undo old blocks, apply new branch)
• [x] insert_tx_into_index (if block is inserted into chain, add index for those block's txs to point to the block hash)
• [x] remove tx from index
• [x] leveldb transaction index. TX hash as key, value points to block key where TX is located
• [ ] get_blocks_since_hash gets future blocks from a given start hash, returns a set size (iterates over all blocks to find start hash, while buffering blocks)
• [x] keeps track of unspent transactions and their unspent txouts (UTXOs)
• [x] Block insertion marks unspent UTXOs as spent

api

• [x] protobuf RPC for local client (elevated operations, wallet management, etc.)
• [ ] protobuf RPC for node RPC / broadcast
• [ ] Switch RPC implementation to GRPC https://github.com/Juniper/grpc-c

---

• [ ] list all dynamic mem allocs // ensure memory hygiene
• [ ] ensure proto -> struct bytearray sizes are correct, or bail
• [ ] setup CI (need to install dependencies on CI environment)

Conscious decisions:

• no raw append-only block storage like bitcoin, using leveldb as the entire storage of the chain rather than only block headers (slower access, more size, faster to develop)
• no double sha256 for merkle root calculation

[andrewvy]

IT'S ALIVE

kinda

empty txless block mining on local (no-net)

[andrewvy]

                                                         ┌──────────────────────────────────────────┐                                                                                      ┌──────────────────────────────────────────┐
                                                         │                                          │                                                                                      │                                          │
                                                         │                                          │                                                                                      │                                          │
                                                         │                                          │                                                                                      │                                          │
                                                         │                                          │                                                                                      │                                          │
                                                         │                                          │                                                                                      │                                          │
                                                         │                                          │                                                                                      │                                          │
                                                         │               Opal Daemon                │                                                                                      │                Opal Peer                 │
                                                         │                                          │                                     P2P Layer                                        │                                          │
                                                         │                                          │                                                                                      │                                          │
                                                         │                                          │                                                                                      │                                          │
                                                         ├────────────┐                ┌────────────┤                                                                                      │                             ┌────────────┤
                                                         │Internal RPC│                │External RPC│                                                                                      │                             │External RPC│
                                                         │   (9898)   │                │   (9899)   │                                                                                      │                             │   (9899)   │
                                                         └────────────┴────────────────┴────────────┘                                                                                      └─────────────────────────────┴────────────┘
                                                                │                             │                                                                                                                                 ▲      
                                                                │                             │                                                                                                                                 │      
                                                                │                             ├─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘      
                                                                │                             │ Protobuf over HTTP                                                                                                                     
                                                                │                             │                                                                                            ┌──────────────────────────────────────────┐
                                              Protobuf over HTTP│                             │                                                                                            │                                          │
      Client Agnostic RPC Layer              ┌──────────────────┤                             │                                                                                            │                                          │
                                             │                  │                             │                                                                                            │                                          │
                                             │                  │                             │                                                                                            │                                          │
                                             │                  │                             │                                                                                            │                                          │
                                             │                  │                             │                                                                                            │                                          │
                                             │                  │                             │                                                                                            │                Opal Peer                 │
                                             │                  │                             │                                                                                            │                                          │
                                             ▼                  ▼                             │                                                                                            │                                          │
                                       ┌───────────┐    ┌───────────────┐                     │                                                                                            │                                          │
                                       │Rust Client│    │Built-in Client│                     │                                                                                            │                             ┌────────────┤
                                       └───────────┘    └───────────────┘                     │                                                                                            │                             │External RPC│
                                                                                              │                                                                                            │                             │   (9899)   │
                                                                                              │                                                                                            └─────────────────────────────┴────────────┘
                                                                                              │                                                                                                                                 ▲      
                                                                                              │                                                                                                                                 │      
                                                                                              ├─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘      
                                                                                              │                                                                                                                                        
                                                                                              │                                                                                            ┌──────────────────────────────────────────┐
                                                                                              │                                                                                            │                                          │
      ┌─────────────────────────┐                                                             │                                                                                            │                                          │
      │ Initialization Sequence │                                                             │                                                                                            │                                          │
      └─────────────────────────┘                                                             │                                                                                            │                                          │
                                                                                              │                                                                                            │                                          │
                                                                                              │                                                                                            │                                          │
      1) Get external facing IP address using UPnP                                            │                                                                                            │                Opal Peer                 │
                                                                                              │                                                                                            │                                          │
      2) Broadcast 'Peer Advertise' message with                                              │                                                                                            │                                          │
      external IP                                                                             │                                                                                            │                                          │
                                                                                              │                                                                                            │                             ┌────────────┤
      3) Call 'Peer List' on seed DNS nodes and keep                                          │                                                                                            │                             │External RPC│
      track in a local list of peers, also saved for                                          │                                                                                            │                             │   (9899)   │
      later peer discovery seed usage.                                                        │                                                                                            └─────────────────────────────┴────────────┘
                                                                                              │                                                                                                                                 ▲      
      4) Start downloading block headers from peers                                           │                                                                                                                                 │      
                                                                                              └─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘      
      5) Validate headers and figure out the 'best                                                                                                                                                                                     
      header chain'                                                                                                                                                                                                                    

      6) Once best header chain has been found, start                                                                                                                                                                                  
      downloading full blocks from peers.                                                                                                                                                                                              

      7) Start validating full blocks and maintain a                                                                                                                                                                                   
      UXTO database                                                                                                                                                                                                                    

      8) You are ready to start accepting TXs and                                                                                                                                                                                      
      Blocks!