feat: persist irc connections between websocket disconnects (#164)

- currently, when the websocket connection is dropped, the irc
  connection is closed immediately. this change makes it so that
  after the websocket connection closed, the user has 3 minutes
  to reconnect before we close the irc connection.
- the 3 minute 'self-destruct' is only triggered when the websocket
  is disconnected and is disabled once there is another connection
- this should help with certain devices (such as iPad) where switching
  apps / tabs seems to close the websocket. i believe that the IRC
  server is sensitive to clients connecting/disconnecting too often and
  will ban users.

Author: evan-buss

.devcontainer/devcontainer.json

@@ -12,11 +12,19 @@
   "remoteUser": "root",
   "features": {
     "ghcr.io/devcontainers/features/go:1": {},
-    "ghcr.io/devcontainers/features/node:1": {}
+    "ghcr.io/devcontainers/features/node:1": {},
+    "ghcr.io/devcontainers/features/docker-in-docker:2": {}
   },
   "customizations": {
     "vscode": {
-      "extensions": ["golang.go", "heybourn.headwind", "esbenp.prettier-vscode", "bradlc.vscode-tailwindcss", "ms-vscode.makefile-tools", "redhat.vscode-yaml"]
+      "extensions": [
+        "golang.go",
+        "heybourn.headwind",
+        "esbenp.prettier-vscode",
+        "bradlc.vscode-tailwindcss",
+        "ms-vscode.makefile-tools",
+        "redhat.vscode-yaml"
+      ]
     }
   }
 }

server/client.go

@@ -60,7 +60,6 @@ type Client struct {
 // reads from this goroutine.
 func (server *server) readPump(c *Client) {
 	defer func() {
-		c.irc.Disconnect()
 		c.conn.Close()
 		server.unregister <- c
 	}()

server/routes.go

@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/evan-buss/openbooks/irc"
 	"io/fs"
 	"log"
 	"net/http"
@@ -17,6 +16,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/evan-buss/openbooks/irc"
+
 	"github.com/go-chi/chi/v5"
 	"github.com/google/uuid"
 )
@@ -90,9 +91,6 @@ func (server *server) serveWs() http.HandlerFunc {
 		client.log.Println("New client created.")
 
 		server.register <- client
-
-		go server.writePump(client)
-		go server.readPump(client)
 	}
 }
 

server/server.go

@@ -103,17 +103,47 @@ func Start(config Config) {
 // The client hub is to be run in a goroutine and handles management of
 // websocket client registrations.
 func (server *server) startClientHub(ctx context.Context) {
+	type selfDestructor struct {
+		timer  *time.Timer
+		client *Client
+	}
+
+	selfDestructors := make(map[uuid.UUID]selfDestructor)
+
 	for {
 		select {
 		case client := <-server.register:
+			if destructor, ok := selfDestructors[client.uuid]; ok {
+				destructor.timer.Stop()
+				server.log.Printf("Client %s reconnected\n", client.uuid.String())
+
+				// Update the existing client's websocket connection to the new one
+				destructor.client.conn = client.conn
+				client = destructor.client
+
+				delete(selfDestructors, client.uuid)
+			}
+
 			server.clients[client.uuid] = client
+			go server.writePump(client)
+			go server.readPump(client)
+
 		case client := <-server.unregister:
-			if _, ok := server.clients[client.uuid]; ok {
-				_, cancel := context.WithCancel(client.ctx)
-				close(client.send)
-				cancel()
-				delete(server.clients, client.uuid)
-			}
+			// Keep the client and IRC connection alive for 3 minutes in case the client reconnects
+			timer := time.AfterFunc(time.Minute*3, func() {
+				if _, ok := selfDestructors[client.uuid]; ok {
+					client.irc.Disconnect()
+					_, cancel := context.WithCancel(client.ctx)
+					close(client.send)
+					cancel()
+					delete(selfDestructors, client.uuid)
+					server.log.Printf("Client %s self-destructed\n", client.uuid.String())
+				}
+			})
+
+			selfDestructors[client.uuid] = selfDestructor{timer, client}
+			delete(server.clients, client.uuid)
+			server.log.Printf("Client %s disconnected\n", client.uuid.String())
 		case <-ctx.Done():
 			for _, client := range server.clients {
 				_, cancel := context.WithCancel(client.ctx)

server/websocket_requests.go

@@ -49,34 +49,50 @@ func (server *server) routeMessage(message Request, c *Client) {
 
 // handle ConnectionRequests and either connect to the server or do nothing
 func (c *Client) startIrcConnection(server *server) {
-	err := core.Join(c.irc, server.config.Server, server.config.EnableTLS)
-	if err != nil {
-		c.log.Println(err)
-		c.send <- newErrorResponse("Unable to connect to IRC server.")
-		return
-	}
+	// The IRC connection could be re-used if it is already connected
+	if !c.irc.IsConnected() {
+		err := core.Join(c.irc, server.config.Server, server.config.EnableTLS)
+		if err != nil {
+			c.log.Println(err)
+			c.send <- newErrorResponse("Unable to connect to IRC server.")
+			return
+		}
 
-	handler := server.NewIrcEventHandler(c)
+		handler := server.NewIrcEventHandler(c)
 
-	if server.config.Log {
-		logger, _, err := util.CreateLogFile(c.irc.Username, server.config.DownloadDir)
-		if err != nil {
-			server.log.Println(err)
+		if server.config.Log {
+			logger, _, err := util.CreateLogFile(c.irc.Username, server.config.DownloadDir)
+			if err != nil {
+				server.log.Println(err)
+			}
+			handler[core.Message] = func(text string) { logger.Println(text) }
 		}
-		handler[core.Message] = func(text string) { logger.Println(text) }
-	}
 
-	go core.StartReader(c.ctx, c.irc, handler)
+		go core.StartReader(c.ctx, c.irc, handler)
+
+		c.send <- ConnectionResponse{
+			StatusResponse: StatusResponse{
+				MessageType:      CONNECT,
+				NotificationType: SUCCESS,
+				Title:            "Welcome, connection established.",
+				Detail:           fmt.Sprintf("IRC username %s", c.irc.Username),
+			},
+			Name: c.irc.Username,
+		}
+
+		return
+	}
 
 	c.send <- ConnectionResponse{
 		StatusResponse: StatusResponse{
 			MessageType:      CONNECT,
-			NotificationType: SUCCESS,
-			Title:            "Welcome, connection established.",
+			NotificationType: NOTIFY,
+			Title:            "Welcome back, re-using open IRC connection.",
 			Detail:           fmt.Sprintf("IRC username %s", c.irc.Username),
 		},
 		Name: c.irc.Username,
 	}
+
 }
 
 // handle SearchRequests and send the query to the book server