Component

1. Crawler This is the core component of the application, basically an engine which start new connections and handle their result. There is only 1 per instance

2. Node A Node describe a node in the Bitcoin network and keep track of some information about it:

type Node struct {
	Timestamp time.Time `json:"timestamp"`
	Info      *Info     `json:"info"`
	Addr      *Addr     `json:"addr"`
	Ping      bool      `json:"ping"`
}

3. Peer A peer is bascially a connection to a Bitcoin node, it's used to communicate with this node

type Peer struct {
	ip        string
	port      int
	conn      net.Conn
	handlers  Handlers
	Info      *Info
	Addrs     []*Addr
	PingNonce []byte
	PingAt    time.Time
	PongAt    time.Time
	queue     chan *message.Message
	onClose   chan *Node
}

Workflow

1. Main

• Init database
• Load known peers
• Start crawlers with known peers
• Load OK peers from database
• Wait for interupt (SIGINT or SIGTERM)

2. On Interupt

• Export nodes to /expot/nodes.json
• Save / Update nodes in DB

3. Create a crawler

• Create a struct crawler
• Register all the provided addr to the crawler
• Start the ResultHandler -> Basically update the status of a Node in map nodes
• Start N worker to handle new nodes
• Start moniroting -> Basically a go routine which log the state of the map of nodes every 10s

4. Worker

• Verify if the Node is already known (if yes stop here)
• Create + setup the new Peer
• Start the Peer
• Send 10 GetAddr message to the Peer
• After 60s close the connection (should be reworked to use context)
• Add the peer (node) to the map of known nodes

5. Create a new Peer

• Create a tcp connection to the IPv4 or IPv6 address
• Init the struct

6. Start a Peer

• Send Version message
• Send Verack message
• Send Ping message
• Send GetAddr message
• Start handler for differents messages