libp2p-rs v0.2.0已经支持Kad-DHT，支持节点通过DHT网络发现节点和内容。
本文主要展示如何在libp2p-rs使用DHT，以及罗列出swarm和kad的部分API。

使用kad

step1: 创建swarm

    let sec = secio::Config::new(keys.clone());    let mux = yamux::Config::new();    let tu = TransportUpgrade::new(TcpConfig::default(), mux, sec);    let mut swarm = Swarm::new(keys.public())        .with_transport(Box::new(tu))        .with_identify(IdentifyConfig::new(false));    swarm.listen_on(vec![listen_addr]).expect("listen on");    let mut swarm_control = swarm.control();

step2: 创建kad

    let store = MemoryStore::new(swarm.local_peer_id().clone());    let kad = Kademlia::new(swarm.local_peer_id().clone(), store);    let kad_handler = kad.handler();    let mut kad_ctrl = kad.control();

step3: 注册kad

将swarm升级，使其具备routing功能。

    // register handler to swarm    swarm = swarm.with_protocol(Box::new(kad_handler)).with_routing(Box::new(kad_ctrl.clone()));

step4: 启动kad和swarm

    kad.start(swarm_control.clone());    swarm.start();

step5: 使用kad

先将bootstrap节点添加到peerstore和路由表，再启动bootstrap。

    kad_control.add_node(bootstrap_peer, vec![bootstrap_addr]).await;    kad_control.bootstrap().await;

step6: 启用cli

集成cli，可调试swarm和kad。

    let mut app = App::new("xCLI").version("v0.1").author("kingwel.xie@139.com");    app.add_subcommand_with_userdata(swarm_cli_commands(), Box::new(swarm_control.clone()));    app.add_subcommand_with_userdata(dht_cli_commands(), Box::new(kad_control.clone()));    app.run();

cli调试

以下只列出部分常用的调试命令，更多玩法请亲自下场解锁。

swarm connection

connection命令可以用于获取当前所有连接及其子流的信息，也可以获取和某个peer的连接信息。

# s conCID   DIR Remote-Peer-Id                                       I/O  Remote-Multiaddr231   In  Qmf3ZX3yHnmzaXFGH5G149HyrAeKRFantVnZ9gZdnuPv1U       2/0  /ip4/114.227.83.230/tcp/24792      (231   Sid(7) In  /ipfs/kad/1.0.0)      (231   Sid(9) In  /ipfs/kad/1.0.0)161   In  QmZC9dZPyJWXSB2Ao2ChGJMjfuFiT7TyKdsGsFEKVSqnnf       0/0  /ip4/212.102.37.201/tcp/40012185  In  QmTmnqSEarcSLJxhehJRKX64pxSkeKn7jS2fDEZFjjt9Bn       1/0  /ip4/114.226.44.86/tcp/3109      (2185  Sid(7) In  /ipfs/kad/1.0.0)2069  In  12D3KooWPtfLkqAVMPP6FNufHvqxPYe55XuAdEZWUn2cPbLLAwuT 1/0  /ip4/111.16.39.80/tcp/17881      (2069  Sid(1) In  /ipfs/kad/1.0.0)2349  In  QmVcXP4bnoCJkUUJinduuM68n5jfSjDj6sKaTjRhHoecpt       1/0  /ip4/83.248.150.24/tcp/42761      (2349  Sid(3) In  /ipfs/kad/1.0.0)492   In  12D3KooWKBkFNUCvyP5PbV2mAhrzcvPi4EPL4vD3CjieGGU9ZcQr 1/0  /ip4/203.145.95.60/tcp/64417      (492   Sid(1) In  /ipfs/kad/1.0.0)18    In  QmP6waLA8S6M8WPoQ5tWPE6xpgtsJ44LGQcq7vDTUAmyob       1/0  /ip4/188.127.190.220/tcp/4001      (18    Sid(7) In  /ipfs/kad/1.0.0)# s con Qmf3ZX3yHnmzaXFGH5G149HyrAeKRFantVnZ9gZdnuPv1UCID   DIR Remote-Peer-Id                                       I/O  Remote-Multiaddr231   In  Qmf3ZX3yHnmzaXFGH5G149HyrAeKRFantVnZ9gZdnuPv1U       2/0  /ip4/114.227.83.230/tcp/24792      (231   Sid(7) In  /ipfs/kad/1.0.0)      (231   Sid(9) In  /ipfs/kad/1.0.0)

dht states

states用于统计迭代查询运行状况，也可以观察当前节点接收到的Kad请求的次数。

# d stTotal refreshes : 1Successful queries   : 4Timeout queries   : 0Query details   : QueryStats { requests: 59, success: 41, failure: 10, duration: 18.198653932s }Kad rx messages : MessageStats { ping: 0, find_node: 17216, get_provider: 559, add_provider: 3667, get_value: 1, put_value: 27 }

dht dump

dump命令用于dump出路由表的信息，使用verbose可以打印详细信息。

# d dpIndex Entries Active244   1       1246   1       1247   2       2248   7       7249   10      8250   20      20251   20      20252   20      20253   20      20254   20      19255   20      20# d dp 1Index Entries Active244   1       1      Qme9PR5oDcSSGoS2He53RqaML4vinDD5CNgxxmV2qPefFP       Conn(false) Some(52292.68894773s) Addrs([])246   1       1      QmboRZYso6VdQ5yfXe1DAj9u8EqouZGUsf2inoqYDtzdf8       Conn(true) Some(4330.367016609s) Addrs([])247   2       2      QmZsbivLpaVpWQ4Mum2nzbEcoXbH7QbftRkQCmmJiTqcUp       Conn(false) Some(77688.875853187s) Addrs([])      QmZaCQ6anyaPuebhLeomzpyKRAY6GnNS5NCU8h7kSjwFKN       Conn(false) Some(43775.12096365s) Addrs(["/ip4/127.0.0.1/tcp/4001", "/ip4/138.68.29.104/tcp/4001", "/ip4/10.46.0.6/tcp/4001", "/ip4/10.138.16.85/tcp/4001", "/ip6/::1/tcp/4001"])

API介绍

目前swarm和kad的API已经比较完善，以下只列出部分常用的API，想了解更多API请直接阅读源码。

swarm

peerstore

    /// Gets the public key by peer_id.    pub fn get_key(&self, peer_id: &PeerId) -> Option<PublicKey>    /// Gets all multiaddr of a peer.    pub fn get_addrs(&self, peer_id: &PeerId) -> Option<Vec<Multiaddr>>    /// Adds a address to address_book by peer_id, if exists, update rtt.    pub fn add_addr(&self, peer_id: &PeerId, addr: Multiaddr, ttl: Duration)    /// Adds many new addresses if they're not already in the peer store.    pub fn add_addrs(&self, peer_id: &PeerId, addrs: Vec<Multiaddr>, ttl: Duration)    /// Clears all multiaddr of a peer from the peer store.    pub fn clear_addrs(&self, peer_id: &PeerId)

connection

    /// Make a new connection towards the remote peer with addresses specified.    pub async fn connect_with_addrs(&mut self, peer_id: PeerId, addrs: Vec<Multiaddr>) -> Result<()>    /// Make a new connection towards the remote peer.    ///    /// It will lookup the peer store for address of the peer, otherwise    /// initiate the routing interface for querying the addresses, if routing    /// is available.    pub async fn new_connection(&mut self, peer_id: PeerId) -> Result<()>    /// Make a new connection towards the remote peer, without using routing(Kad-DHT).    pub async fn new_connection_no_routing(&mut self, peer_id: PeerId) -> Result<()>    /// Close connection towards the remote peer.    pub async fn disconnect(&mut self, peer_id: PeerId) -> Result<()>

stream

    /// Open a new outbound stream towards the remote peer.    ///    /// It will lookup the peer store for address of the peer,    /// otherwise initiate the routing interface for address querying,    /// when routing is enabled. In the end, it will open an outgoing    /// sub-stream when the connection is eventually established.    pub async fn new_stream(&mut self, peer_id: PeerId, pids: Vec<ProtocolId>) -> Result<Substream>    /// Open a new outbound stream towards the remote peer, without routing.    pub async fn new_stream_no_routing(&mut self, peer_id: PeerId, pids: Vec<ProtocolId>) -> Result<Substream>     /// Open a new outbound stream towards the remote peer, without routing.    pub async fn new_stream_no_routing(&mut self, peer_id: PeerId, pids: Vec<ProtocolId>) -> Result<Substream>

kad

    /// Add a node and its listening addresses to KBuckets.    pub async fn add_node(&mut self, peer_id: PeerId, addrs: Vec<Multiaddr>)    /// Add a node and its listening addresses to KBuckets.    pub async fn remove_node(&mut self, peer_id: PeerId)    /// Initiate bootstrapping.    ///    /// In general it should be done only once upon Kad startup.    pub async fn bootstrap(&mut self)    /// Lookup the closer peers with the given key.    pub async fn lookup(&mut self, key: record::Key) -> Result<Vec<KadPeer>>    /// Lookup the given peer.    pub async fn find_peer(&mut self, peer_id: &PeerId) -> Result<KadPeer>    /// Put value in local and other peers which closest to the given key.    pub async fn put_value(&mut self, key: Vec<u8>, value: Vec<u8>) -> Result<()>    /// Get value from local and other peers  which closest to the given key.    pub async fn get_value(&mut self, key: Vec<u8>) -> Result<Vec<u8>>    /// Announce to peers which closer to the given key that self provide content.    pub async fn provide(&mut self, key: Vec<u8>) -> Result<()>    /// Find peers who provide content.    pub async fn find_providers(&mut self, key: Vec<u8>, count: usize) -> Option<Vec<KadPeer>>

总结

在启动kad和swarm后，就可以通过句柄（controller），调用API。当前
swarm的API已经比较完善，目前已经可以支持Kad-DHT这种比较复杂的协议，这也为新协议的添加创造了条件。

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libp2p-rs kad 使用及调试方法