From 499a0e19cb23c25c09f835e62967c2238b0e4fc1 Mon Sep 17 00:00:00 2001
From: ValdikSS <iam@valdikss.org.ru>
Date: Sat, 13 Nov 2021 21:31:49 +0000
Subject: [PATCH] Add TCP keep alive support in Linux

---
 transport/internet/sockopt_linux.go   | 16 ++++++++++++++--
 transport/internet/system_dialer.go   |  6 +++++-
 transport/internet/system_listener.go |  4 ++++
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/transport/internet/sockopt_linux.go b/transport/internet/sockopt_linux.go
index 0ec2995ae..c6bcf0e70 100644
--- a/transport/internet/sockopt_linux.go
+++ b/transport/internet/sockopt_linux.go
@@ -59,10 +59,16 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 			}
 		}
 
-		if config.TcpKeepAliveInterval != 0 {
+		if config.TcpKeepAliveInterval > 0 {
 			if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, int(config.TcpKeepAliveInterval)); err != nil {
 				return newError("failed to set TCP_KEEPINTVL", err)
 			}
+			if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPIDLE, int(config.TcpKeepAliveIdle)); err != nil {
+				return newError("failed to set TCP_KEEPIDLE", err)
+			}
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
 		}
 	}
 
@@ -93,10 +99,16 @@ func applyInboundSocketOptions(network string, fd uintptr, config *SocketConfig)
 			}
 		}
 
-		if config.TcpKeepAliveInterval != 0 {
+		if config.TcpKeepAliveInterval > 0 {
 			if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, int(config.TcpKeepAliveInterval)); err != nil {
 				return newError("failed to set TCP_KEEPINTVL", err)
 			}
+			if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPIDLE, int(config.TcpKeepAliveIdle)); err != nil {
+				return newError("failed to set TCP_KEEPIDLE", err)
+			}
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
 		}
 	}
 
diff --git a/transport/internet/system_dialer.go b/transport/internet/system_dialer.go
index eb6ffffa7..a696f26d3 100644
--- a/transport/internet/system_dialer.go
+++ b/transport/internet/system_dialer.go
@@ -63,10 +63,14 @@ func (d *DefaultSystemDialer) Dial(ctx context.Context, src net.Address, dest ne
 			dest: destAddr,
 		}, nil
 	}
-
+	goStdKeepAlive := time.Duration(0)
+	if sockopt.TcpKeepAliveIdle != 0 {
+		goStdKeepAlive = time.Duration(-1)
+	}
 	dialer := &net.Dialer{
 		Timeout:   time.Second * 16,
 		LocalAddr: resolveSrcAddr(dest.Network, src),
+		KeepAlive: goStdKeepAlive,
 	}
 
 	if sockopt != nil || len(d.controllers) > 0 {
diff --git a/transport/internet/system_listener.go b/transport/internet/system_listener.go
index d59aa623d..73e19c118 100644
--- a/transport/internet/system_listener.go
+++ b/transport/internet/system_listener.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"runtime"
 	"syscall"
+	"time"
 
 	"github.com/pires/go-proxyproto"
 
@@ -49,6 +50,9 @@ func (dl *DefaultListener) Listen(ctx context.Context, addr net.Addr, sockopt *S
 		network = addr.Network()
 		address = addr.String()
 		lc.Control = getControlFunc(ctx, sockopt, dl.controllers)
+		if sockopt.TcpKeepAliveIdle != 0 {
+			lc.KeepAlive = time.Duration(-1)
+		}
 	case *net.UnixAddr:
 		lc.Control = nil
 		network = addr.Network()