From 8affb6210e1531f51ae2cf2cd631e0bbe2e7e95a Mon Sep 17 00:00:00 2001
From: Reese Norris <reese.norris@gmail.com>
Date: Sun, 6 Jul 2025 17:40:11 -0700
Subject: [PATCH] add client timeout via net/Conn SetDeadline

---
 fsd/client.go | 2 ++
 fsd/conn.go   | 4 +++-
 fsd/env.go    | 3 +++
 fsd/util.go   | 6 ++++++
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/fsd/client.go b/fsd/client.go
index 3441fe8..b3c8247 100644
--- a/fsd/client.go
+++ b/fsd/client.go
@@ -108,6 +108,8 @@ func (s *Server) eventLoop(client *Client) {
 	go client.senderWorker()
 
 	for {
+		// Set deadline and attempt to read
+		client.conn.SetReadDeadline(getTimeBySecondsInFuture(s.cfg.ConnectionTimeoutSeconds))
 		if !client.scanner.Scan() {
 			return
 		}
diff --git a/fsd/conn.go b/fsd/conn.go
index 41ae4d1..4cb351e 100644
--- a/fsd/conn.go
+++ b/fsd/conn.go
@@ -35,9 +35,11 @@ func (s *Server) handleConn(ctx context.Context, conn net.Conn) {
 			fmt.Println(err)
 		}
 	}()
-
 	defer conn.Close()
 
+	// Set timeout for login phase
+	conn.SetDeadline(getTimeBySecondsInFuture(s.cfg.ConnectionTimeoutSeconds))
+
 	if err := sendServerIdent(conn); err != nil {
 		fmt.Printf("Error sending server ident: %v\n", err)
 		return
diff --git a/fsd/env.go b/fsd/env.go
index b4befc1..fd32fbf 100644
--- a/fsd/env.go
+++ b/fsd/env.go
@@ -16,6 +16,9 @@ type ServerConfig struct {
 	NumMetarWorkers int `env:"NUM_METAR_WORKERS, default=4"` // Number of METAR fetch workers to run
 
 	ServiceHTTPListenAddr string `env:"SERVICE_HTTP_LISTEN_ADDR, default=:13618"`
+
+	// Seconds after which a connection will be closed for inactivity
+	ConnectionTimeoutSeconds int `env:"CONNECTION_TIMEOUT_SECONDS, default=30"`
 }
 
 func loadServerConfig(ctx context.Context) (config *ServerConfig, err error) {
diff --git a/fsd/util.go b/fsd/util.go
index 8629527..692c243 100644
--- a/fsd/util.go
+++ b/fsd/util.go
@@ -7,6 +7,7 @@ import (
 	"slices"
 	"strconv"
 	"strings"
+	"time"
 )
 
 // FSD error codes
@@ -418,3 +419,8 @@ func sendSendFastPacket(client *Client, enabled bool) {
 
 	client.send(builder.String())
 }
+
+// getTimeBySecondsInFuture returns time.Now + seconds
+func getTimeBySecondsInFuture(seconds int) time.Time {
+	return time.Now().Add(time.Duration(seconds) * time.Second)
+}