converge/pkg/converge/admin.go

package converge

import (
	"cidebug/pkg/iowrappers"
	"fmt"
	"github.com/hashicorp/yamux"
	"io"
	"log"
	"net"
	"sync"
	"time"
)

type Agent struct {
	// server session
	clientSession *yamux.Session
	publicId      string
	startTime     time.Time
}

type Client struct {
	publicId  string
	agent     net.Conn
	client    iowrappers.ReadWriteAddrCloser
	startTime time.Time
}

func NewAgent(publicId string,
	agentSession *yamux.Session) *Agent {
	return &Agent{
		clientSession: agentSession,
		publicId:      publicId,
		startTime:     time.Now(),
	}
}

func NewClient(publicId string, clientConn iowrappers.ReadWriteAddrCloser,
	agentConn net.Conn) *Client {
	return &Client{
		publicId:  publicId,
		agent:     agentConn,
		client:    clientConn,
		startTime: time.Now(),
	}
}

type Admin struct {
	// map of public id to agent
	mutex   sync.Mutex
	agents  map[string]*Agent
	clients []*Client
}

func NewAdmin() *Admin {
	admin := Admin{
		mutex:   sync.Mutex{},
		agents:  make(map[string]*Agent),
		clients: make([]*Client, 0), // not strictly needed
	}
	return &admin
}

func (admin *Admin) logStatus() {
	log.Printf("%-20s %-20s %-20s\n", "AGENT", "ACTIVE_SINCE", "REMOTE_ADDRESS")
	for _, agent := range admin.agents {
		agent.clientSession.RemoteAddr()
		log.Printf("%-20s %-20s %-20s\n", agent.publicId,
			agent.startTime.Format(time.DateTime),
			agent.clientSession.RemoteAddr().String())
	}
	log.Println("")
	log.Printf("%-20s %-20s %-20s\n", "CLIENT", "ACTIVE_SINCE", "REMOTE_ADDRESS")
	for _, client := range admin.clients {
		log.Printf("%-20s %-20s %-20s", client.publicId,
			client.startTime.Format(time.DateTime),
			client.client.RemoteAddr())
	}
	log.Printf("\n")
}

func (admin *Admin) addAgent(publicId string, conn io.ReadWriteCloser) (*Agent, error) {
	admin.mutex.Lock()
	defer admin.mutex.Unlock()

	agent := admin.agents[publicId]
	if agent != nil {
		return nil, fmt.Errorf("A different agent with same publicId '%s' already registered", publicId)
	}

	clientSession, err := yamux.Client(conn, nil)
	if err != nil {
		return nil, err
	}
	agent = NewAgent(publicId, clientSession)
	admin.agents[publicId] = agent
	admin.logStatus()
	return agent, nil
}

func (admin *Admin) addClient(publicId string, clientConn iowrappers.ReadWriteAddrCloser) (*Client, error) {
	admin.mutex.Lock()
	defer admin.mutex.Unlock()

	agent := admin.agents[publicId]
	if agent == nil {
		// we should setup on-demend connections ot agents later.
		return nil, fmt.Errorf("No agent found for publicId '%s'", publicId)
	}

	agentConn, err := agent.clientSession.Open()
	if err != nil {
		return nil, err
	}
	log.Println("Successful websocket connection to agent")

	client := NewClient(publicId, clientConn, agentConn)
	admin.clients = append(admin.clients, client)
	admin.logStatus()
	return client, nil
}

func (admin *Admin) RemoveAgent(publicId string) error {
	admin.mutex.Lock()
	defer admin.mutex.Unlock()

	agent := admin.agents[publicId]
	if agent == nil {
		return fmt.Errorf("Cannot remove agent: '%s' not found", publicId)
	}
	log.Printf("Removing agent: '%s'", publicId)
	err := agent.clientSession.Close()
	if err != nil {
		log.Printf("Could not close yamux client session for '%s'\n", publicId)
	}
	delete(admin.agents, publicId)
	admin.logStatus()
	return nil
}

func (admin *Admin) RemoveClient(client *Client) error {
	admin.mutex.Lock()
	defer admin.mutex.Unlock()

	log.Printf("Removing client: '%s' created at %s\n", client.publicId,
		client.startTime.Format("2006-01-02 15:04:05"))
	// try to explicitly close connection to the agent.
	_ = client.agent.Close()
	_ = client.client.Close()

	for i, _client := range admin.clients {
		if _client == _client {
			admin.clients = append(admin.clients[:i], admin.clients[i+1:]...)
			break
		}
	}
	admin.logStatus()
	return nil
}

func (admin *Admin) Register(publicId string, conn io.ReadWriteCloser) error {
	defer conn.Close()
	// TODO: remove agent return value
	agent, err := admin.addAgent(publicId, conn)
	if err != nil {
		return err
	}
	defer func() {
		admin.RemoveAgent(publicId)
	}()
	log.Printf("Agent registered: '%s'\n", publicId)
	for !agent.clientSession.IsClosed() {
		time.Sleep(250 * time.Millisecond)
	}
	return nil
}

func (admin *Admin) Connect(publicId string, conn iowrappers.ReadWriteAddrCloser) error {
	defer conn.Close()
	client, err := admin.addClient(publicId, conn)
	if err != nil {
		return err
	}
	defer func() {
		admin.RemoveClient(client)
	}()
	log.Printf("Connecting client and agent: '%s'\n", publicId)

	iowrappers.SynchronizeStreams(client.client, client.agent)
	return nil
}

func (admin *Admin) log() {
	log.Println("CONNECTIONS")
	for _, agent := range admin.agents {
		log.Println(agent.publicId)
	}
	log.Printf("\n")
}