net: bifurcate the TCP Keep-Alive mechanism into Solaris and illumos

Fixes #65812

Change-Id: I63facb32eeddbe9b6e0279f1c039779ba2e2ab7d
Reviewed-on: https://go-review.googlesource.com/c/go/+/575015
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Commit-Queue: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

7 files changed, 136 insertions, 10 deletions

diff --git a/src/net/tcpconn_keepalive_conf_posix_test.go b/src/net/tcpconn_keepalive_conf_posix_test.go
index 5b57504926..3cf5f7e66c 100644
--- a/src/net/tcpconn_keepalive_conf_posix_test.go
+++ b/src/net/tcpconn_keepalive_conf_posix_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || windows
+//go:build aix || darwin || dragonfly || freebsd || illumos || linux || netbsd || windows
 
 package net
 
diff --git a/src/net/tcpconn_keepalive_illumos_test.go b/src/net/tcpconn_keepalive_illumos_test.go
new file mode 100644
index 0000000000..56863309b6
--- /dev/null
+++ b/src/net/tcpconn_keepalive_illumos_test.go
@@ -0,0 +1,120 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build illumos
+
+package net
+
+import (
+	"syscall"
+	"testing"
+	"time"
+)
+
+func getCurrentKeepAliveSettings(fd fdType) (cfg KeepAliveConfig, err error) {
+	tcpKeepAlive, err := syscall.GetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_KEEPALIVE)
+	if err != nil {
+		return
+	}
+	tcpKeepAliveIdle, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPIDLE)
+	if err != nil {
+		return
+	}
+	tcpKeepAliveInterval, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPINTVL)
+	if err != nil {
+		return
+	}
+	tcpKeepAliveCount, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPCNT)
+	if err != nil {
+		return
+	}
+	cfg = KeepAliveConfig{
+		Enable:   tcpKeepAlive != 0,
+		Idle:     time.Duration(tcpKeepAliveIdle) * time.Second,
+		Interval: time.Duration(tcpKeepAliveInterval) * time.Second,
+		Count:    tcpKeepAliveCount,
+	}
+	return
+}
+
+func verifyKeepAliveSettings(t *testing.T, fd fdType, oldCfg, cfg KeepAliveConfig) {
+	const defaultTcpKeepAliveAbortThreshold = 8 * time.Minute // default value on illumos
+
+	if cfg.Idle == 0 {
+		cfg.Idle = defaultTCPKeepAliveIdle
+	}
+	if cfg.Interval == 0 {
+		cfg.Interval = defaultTCPKeepAliveInterval
+	}
+	if cfg.Count == 0 {
+		cfg.Count = defaultTCPKeepAliveCount
+	}
+
+	if cfg.Idle == -1 {
+		cfg.Idle = oldCfg.Idle
+	}
+	// Check out the comment on KeepAliveConfig and the illumos code:
+	// https://github.com/illumos/illumos-gate/blob/0886dcadf4b2cd677c3b944167f0d16ccb243616/usr/src/uts/common/inet/tcp/tcp_opt_data.c#L786-L861
+	tcpKeepAliveAbortThreshold := defaultTcpKeepAliveAbortThreshold
+	switch {
+	case cfg.Interval == -1 && cfg.Count == -1:
+		cfg.Interval = oldCfg.Interval
+		cfg.Count = oldCfg.Count
+	case cfg.Interval == -1 && cfg.Count > 0:
+		cfg.Interval = defaultTcpKeepAliveAbortThreshold / time.Duration(cfg.Count)
+	case cfg.Count == -1 && cfg.Interval > 0:
+		cfg.Count = int(defaultTcpKeepAliveAbortThreshold / cfg.Interval)
+	case cfg.Interval > 0 && cfg.Count > 0:
+		// TCP_KEEPALIVE_ABORT_THRESHOLD will be recalculated only when both TCP_KEEPINTVL
+		// and TCP_KEEPCNT are set, otherwise it will remain the default value.
+		tcpKeepAliveAbortThreshold = cfg.Interval * time.Duration(cfg.Count)
+	}
+
+	tcpKeepAlive, err := syscall.GetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_KEEPALIVE)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if (tcpKeepAlive != 0) != cfg.Enable {
+		t.Fatalf("SO_KEEPALIVE: got %t; want %t", tcpKeepAlive != 0, cfg.Enable)
+	}
+
+	tcpKeepAliveIdle, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPIDLE)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if time.Duration(tcpKeepAliveIdle)*time.Second != cfg.Idle {
+		t.Fatalf("TCP_KEEPIDLE: got %ds; want %v", tcpKeepAliveIdle, cfg.Idle)
+	}
+	tcpKeepAliveThreshold, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_KEEPALIVE_THRESHOLD)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if time.Duration(tcpKeepAliveThreshold)*time.Millisecond != cfg.Idle {
+		t.Fatalf("TCP_KEEPALIVE_THRESHOLD: got %dms; want %v", tcpKeepAliveThreshold, cfg.Idle)
+	}
+
+	tcpKeepAliveInterval, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPINTVL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if time.Duration(tcpKeepAliveInterval)*time.Second != cfg.Interval {
+		t.Fatalf("TCP_KEEPINTVL: got %ds; want %v", tcpKeepAliveInterval, cfg.Interval)
+	}
+
+	tcpKeepAliveCount, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall_TCP_KEEPCNT)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if tcpKeepAliveCount != cfg.Count {
+		t.Fatalf("TCP_KEEPCNT: got %d; want %d", tcpKeepAliveCount, cfg.Count)
+	}
+
+	tcpKeepAliveAbortInterval, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_KEEPALIVE_ABORT_THRESHOLD)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if time.Duration(tcpKeepAliveAbortInterval)*time.Millisecond != tcpKeepAliveAbortThreshold {
+		t.Fatalf("TCP_KEEPALIVE_ABORT_THRESHOLD: got %dms; want %v", tcpKeepAliveAbortInterval, tcpKeepAliveAbortThreshold)
+	}
+}
diff --git a/src/net/tcpconn_keepalive_solaris_test.go b/src/net/tcpconn_keepalive_solaris_test.go
index bd9dca7c5b..bb0d851aba 100644
--- a/src/net/tcpconn_keepalive_solaris_test.go
+++ b/src/net/tcpconn_keepalive_solaris_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build solaris
+//go:build solaris && !illumos
 
 package net
 
diff --git a/src/net/tcpconn_keepalive_test.go b/src/net/tcpconn_keepalive_test.go
index 8eb6f2ea4e..665307d1cd 100644
--- a/src/net/tcpconn_keepalive_test.go
+++ b/src/net/tcpconn_keepalive_test.go
@@ -138,18 +138,15 @@ func TestTCPConnKeepAliveConfig(t *testing.T) {
 	if err := ls.buildup(handler); err != nil {
 		t.Fatal(err)
 	}
-	ra, err := ResolveTCPAddr("tcp", ls.Listener.Addr().String())
-	if err != nil {
-		t.Fatal(err)
-	}
 	for _, cfg := range testConfigs {
-		c, err := DialTCP("tcp", nil, ra)
+		d := Dialer{KeepAlive: -1} // avoid setting default values before the test
+		c, err := d.Dial("tcp", ls.Listener.Addr().String())
 		if err != nil {
 			t.Fatal(err)
 		}
 		defer c.Close()
 
-		sc, err := c.SyscallConn()
+		sc, err := c.(*TCPConn).SyscallConn()
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -167,7 +164,7 @@ func TestTCPConnKeepAliveConfig(t *testing.T) {
 			t.Fatal(errHook)
 		}
 
-		if err := c.SetKeepAliveConfig(cfg); err != nil {
+		if err := c.(*TCPConn).SetKeepAliveConfig(cfg); err != nil {
 			t.Fatal(err)
 		}
 
diff --git a/src/net/tcpsock.go b/src/net/tcpsock.go
index 701048896c..0b7984f5f7 100644
--- a/src/net/tcpsock.go
+++ b/src/net/tcpsock.go
@@ -126,6 +126,13 @@ type TCPConn struct {
 // By contrast, if only one of Idle and Interval is set to a non-negative value,
 // the other will be set to the system default value, and ultimately,
 // set both Idle and Interval to negative values if you want to leave them unchanged.
+//
+// Also note that on illumos distributions like OmniOS that support TCP Keep-Alive,
+// setting only one of Idle and Interval to a non-negative value along with the
+// negative other one will result in the negative one being recalculated as the
+// quotient of tcp_keepalive_abort_interval(eight minutes as default) and the
+// non-negative one. Thus, you may as well set the other one to a non-negative
+// value if you've already set one of Idle and Interval.
 type KeepAliveConfig struct {
 	// If Enable is true, keep-alive probes are enabled.
 	Enable bool
diff --git a/src/net/tcpsockopt_solaris.go b/src/net/tcpsockopt_solaris.go
index 44eb9cd09e..ba27e13b21 100644
--- a/src/net/tcpsockopt_solaris.go
+++ b/src/net/tcpsockopt_solaris.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !illumos
+
 package net
 
 import (
diff --git a/src/net/tcpsockopt_unix.go b/src/net/tcpsockopt_unix.go
index f3526e4962..1f7617897a 100644
--- a/src/net/tcpsockopt_unix.go
+++ b/src/net/tcpsockopt_unix.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || dragonfly || freebsd || linux || netbsd
+//go:build aix || dragonfly || freebsd || illumos || linux || netbsd
 
 package net