p2p-libp2p.pdf

Transcript

1. libp2p koganezawa@MoneyForward Financial
2. Agenda • About libp2p • libp2p architecture • Let's code a blockchain! ◦ About shared objects ◦ Required import packages for P2P ◦ BlockChain specific functions ◦ Host to deal with incoming data steams • Demo
3. About libp2p ➢ libp2p... ◦ modular network stack ( network framework ) for creating p2p apps ◦ the modular P2P network stack by IPFS for better decentralized computing
4. ➢ Adopters About libp2p Polkadot Ethereum2.0 MetaMask OpenBazaar Filecoin IPFS
5. About libp2p ➢ Languages
6. About libp2p ➢ P2P Application vs. Web Application: What's the Difference? ▪ client also acts as a server ▪ It is not fixed function like server client model • dial / listen both possible
7. libp2p architecture ➢ Indentity ➢ multiaddr ➢ Peer Routing ➢ Swarm ➢ Distributed Record Store ➢ Discovery
8. libp2p architecture ➢ Indentity ◦ Upon first connecting, peers exchange public keys, ◦ check: multihash(other.PublicKey) equals other.NodeId. ◦ If not the connection is terminated. ➢ What is multihash? ◦ Multihash is a protocol for differentiating outputs from various well-established cryptographic hash functions, ◦ and allow multiple hash functions to coexist. ◦ varint hash function code(tag: multihash) ▪ https://github.com/multiformats/multicodec/blob/master/table.csv
9. ➢ Indentity ◦ ID for identifying distributed nodes libp2p architecture # Identity generation:
10. libp2p architecture ➢ multihash # Format: # Binary example (only 4 bytes for simplicity):
11. # Format: ➢ multiaddr ◦ Multiple protocols are multiplexed using only one port libp2p architecture
12. ➢ Peer Routing ◦ kad-routing ▪ kad-routing implements the Kademlia Routing table ▪ where each peer holds a set of k-buckets ▪ each of them containing several PeerInfo objects from other peers in the network. libp2p architecture
13. ➢ Peer Routing ◦ What is Kademlia? ▪ Kademlia is a distributed hash table for decentralized peer-to-peer computer networks designed by Petar Maymounkov and David Mazières in 2002 • Kademlia stores values in nodes whose ids are “nearest” ◦ using XOR-distance to the key. • The ID uses the hash value of the IP address. • see: https://libp2p.github.io/js-libp2p-kad-dht/ libp2p architecture 001
14. ➢ Peer Routing ◦ mDNS-routing ▪ mDNS-routing uses mDNS probes to identify if local area network peers have a given key or they are simply present. ◦ other-routing-mechanisms ▪ other Peer Routing mechanisms can be implemented libp2p architecture
15. ➢ Swarm ◦ Conn-a connection to a single Peer ▪ MultiConn-a set of connections to a single Peer ▪ SecureConn-an encrypted (tls-like) connection ◦ Swarm-holds connections to Peers ▪ multiplexes from / to each MultiConn ◦ Muxer-Multiples between Services and Swarm. Handles Request / Reply. ▪ Service-connects between an outside client service and Network. ▪ Handler-the client service part that handles requests libp2p architecture
16. ➢ Distributed Record Store ◦ A system to store and distribute records. ◦ Records are small entries used by other systems for signaling, establishing links, announcing peers or content, and so on. They have a similar role to DNS in the broader Internet. libp2p architecture
17. ➢ Discovery ◦ mDNS-discovery ▪ mDNS-discovery is a Discovery Protocol that uses mDNS over local area networks. ▪ It emits mDNS beacons to find if there are more peers available. ◦ Random-Walk ▪ Random-Walk is a Discovery Protocol for DHTs (and other protocols with routing tables). ▪ It makes random DHT queries in order to learn about a large number of peers quickly. ▪ at the expense of a small load at the very beginning. ◦ Bootstrap-List ▪ Bootstrap-List is a Discovery Protocol that uses local storage to cache the addresses of highly stable (and somewhat trusted) peers available in the network libp2p architecture
18. ➢ Required import packages for go-libp2p Let's code a blockchain! library module description github.com/libp2p/go-libp2p libp2p dial / listen, network package github.com/libp2p/go-libp2p-net github.com/libp2p/go-libp2p-host swarm protocol/stream muxer github.com/libp2p/go-libp2p-peerstore distributed record store an object to manage peers, their addresses, and other metadata about them. github.com/libp2p/go-libp2p-peer utilities PKI-based identity management github.com/libp2p/go-libp2p-protocol utilities type for protoco github.com/libp2p/go-libp2p-crypto utilities various cryptographic utilities
19. ➢ About shared objects Let's code a blockchain!
20. ➢ BlockChain specific functions Let's code a blockchain!
21. ➢ BlockChain specific functions Let's code a blockchain!
22. ➢ BlockChain specific functions Let's code a blockchain!
23. ➢ Host to deal with incoming data steams Let's code a blockchain!
24. ➢ New Stream ◦ We have a peer ID and a target Addr so we add it to the peer store ◦ so libp2p knows how to contact it Let's code a blockchain!
25. ➢ Host to deal with incoming data steams ◦ ReadBlockChain Let's code a blockchain!
26. ➢ Host to deal with incoming data steams ◦ WriteBlockChain is broadcast Let's code a blockchain!
27. ➢ Host to deal with incoming data steams ◦ WriteBlockChain is broadcast Let's code a blockchain!
28. ➢ BasicHost ◦ Generate boot node Let's code a blockchain!
29. ➢ Host to deal with incoming data steams ◦ main Let's code a blockchain!
30. Demo!
31. Next Action ➢ demo devp2p!!
32. • libp2p-specs • libp2p.io • ÐΞVp2p • code-a-simple-p2p-blockchain-in-go • ethereum-wireshark-dissectors • ethereum-swarm References