From 1141698a92c70fbd08edc4370815612b4e5766ad Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Tue, 18 Feb 2020 17:26:17 +0100
Subject: [PATCH] Enable TCP keep-alive on all connections

---
 server.go   | 17 +++++++++++++++++
 upstream.go |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/server.go b/server.go
index e3a6ff6..7777040 100644
--- a/server.go
+++ b/server.go
@@ -5,10 +5,25 @@ import (
 	"log"
 	"net"
 	"sync"
+	"time"
 
 	"gopkg.in/irc.v3"
 )
 
+// TODO: make configurable
+var keepAlivePeriod = time.Minute
+
+func setKeepAlive(c net.Conn) error {
+	tcpConn, ok := c.(*net.TCPConn)
+	if !ok {
+		return fmt.Errorf("cannot enable keep-alive on a non-TCP connection")
+	}
+	if err := tcpConn.SetKeepAlive(true); err != nil {
+		return err
+	}
+	return tcpConn.SetKeepAlivePeriod(keepAlivePeriod)
+}
+
 type Logger interface {
 	Print(v ...interface{})
 	Printf(format string, v ...interface{})
@@ -177,6 +192,8 @@ func (s *Server) Serve(ln net.Listener) error {
 			return fmt.Errorf("failed to accept connection: %v", err)
 		}
 
+		setKeepAlive(netConn)
+
 		dc := newDownstreamConn(s, netConn)
 		go func() {
 			s.lock.Lock()
diff --git a/upstream.go b/upstream.go
index f8b9ac2..a21f6c8 100644
--- a/upstream.go
+++ b/upstream.go
@@ -56,6 +56,8 @@ func connectToUpstream(u *user, upstream *Upstream) (*upstreamConn, error) {
 		return nil, fmt.Errorf("failed to dial %q: %v", upstream.Addr, err)
 	}
 
+	setKeepAlive(netConn)
+
 	msgs := make(chan *irc.Message, 64)
 	uc := &upstreamConn{
 		upstream: upstream,