chatServer.go

package nan0chat

import (
	"github.com/Yomiji/nan0"
	"time"
			"fmt"
	"github.com/golang/protobuf/proto"
)

type ChatServer struct {
	users    map[int64]*ConnectedUser
	internal *nan0.Service
}

type ConnectedUser struct {
	conn nan0.NanoServiceWrapper
}

func Serve(port int) (err error) {
	// create the server descriptor
	service := &ChatServer{
		internal: &nan0.Service{
			ServiceName: "Nan0 Chat",
			Port:        int32(port),
			HostName:    "localhost",
			StartTime:   time.Now().Unix(),
			ServiceType: "Chat",
		},
		users: make(map[int64]*ConnectedUser),
	}

	// build server and start listening for clients
	server, err := service.internal.NewNanoBuilder().
		AddMessageIdentity(proto.Clone(new(ChatMessage))).
		EnableEncryption(KeysToNan0Bytes(*EncryptKey, *Signature)).
		ToggleWriteDeadline(true).
	BuildServer(nil)

	if err != nil {
		return err
	}

	// shutdown server on exit or error
	defer server.Shutdown()

	fmt.Println("Secure nan0chat server started. Use interrupt command (ctrl+c) to exit.")

	// start handling client requests indefinitely
	for ; ; {
		func() {
			defer func() { recover() }()

			// when we get a new connection, create a random user id, save the connection to the map of connected clients
			conn := <-server.GetConnections()
			newUserId := random.Int63()
			service.users[newUserId] = &ConnectedUser{
				conn: conn,
			}

			fmt.Printf("New user %v connected.\n", newUserId)

			// start a service handler for all messages generated by that client
			go service.startDistributor(newUserId, conn)
		}()
	}

	return
}

// Starts a handler for the given user that will distribute the user's messages to each other connected user
func (s *ChatServer) startDistributor(userId int64, conn nan0.NanoServiceWrapper) {
	defer conn.Close()
	receiver := conn.GetReceiver()
	for ; ; {
		msg := <-receiver

		// if we have some data inside the message
		if msg != nil {
			// broadcast the message to all connected clients that are NOT the client that generated the message
			// we assume that the subject client has kept track of its own message
			for id, user := range s.users {
				if id != userId {
					sender := user.conn.GetSender()
					sender <- msg
				}
			}
		}
	}
}