Enable TCP keep-alive on all connections

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()

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,