tcp: ignore ENOPROTOOPT returned by SetKeepAlive on some platforms

Signed-off-by: Achille Roussel <[email protected]>

Author: achille-roussel

connector.go

@@ -11,11 +11,13 @@ package mysql
 import (
 	"context"
 	"database/sql/driver"
+	"errors"
 	"fmt"
 	"net"
 	"os"
 	"strconv"
 	"strings"
+	"syscall"
 )
 
 type connector struct {
@@ -98,13 +100,11 @@ func (c *connector) Connect(ctx context.Context) (driver.Conn, error) {
 	}
 
 	// Enable TCP Keepalives on TCP connections
-	if tc, ok := mc.netConn.(*net.TCPConn); ok {
-		if err := tc.SetKeepAlive(true); err != nil {
-			// Don't send COM_QUIT before handshake.
-			mc.netConn.Close()
-			mc.netConn = nil
-			return nil, err
-		}
+	if err := enableKeepAlive(mc.netConn); err != nil {
+		// Don't send COM_QUIT before handshake.
+		mc.netConn.Close()
+		mc.netConn = nil
+		return nil, err
 	}
 
 	// Call startWatcher for context support (From Go 1.8)
@@ -188,3 +188,18 @@ func (c *connector) Connect(ctx context.Context) (driver.Conn, error) {
 func (c *connector) Driver() driver.Driver {
 	return &MySQLDriver{}
 }
+
+func enableKeepAlive(nc net.Conn) error {
+	if tc, ok := nc.(*net.TCPConn); ok {
+		if err := tc.SetKeepAlive(true); err != nil {
+			// The underlying setsockopt syscall may return ENOPROTOOPT if the
+			// system does not support TCP keep-alive. We can still successfully
+			// use the driver without keep-alive support, which is why we choose
+			// to silence it here.
+			if !errors.Is(err, syscall.ENOPROTOOPT) {
+				return err
+			}
+		}
+	}
+	return nil
+}