Feature: mark on socket (#1705)

component/dialer/mark_linux.go

@@ -0,0 +1,44 @@
+//go:build linux
+// +build linux
+
+package dialer
+
+import (
+	"net"
+	"syscall"
+)
+
+func bindMarkToDialer(mark int, dialer *net.Dialer, _ string, _ net.IP) {
+	dialer.Control = bindMarkToControl(mark, dialer.Control)
+}
+
+func bindMarkToListenConfig(mark int, lc *net.ListenConfig, _, address string) {
+	lc.Control = bindMarkToControl(mark, lc.Control)
+}
+
+func bindMarkToControl(mark int, chain controlFn) controlFn {
+	return func(network, address string, c syscall.RawConn) (err error) {
+		defer func() {
+			if err == nil && chain != nil {
+				err = chain(network, address, c)
+			}
+		}()
+
+		ipStr, _, err := net.SplitHostPort(address)
+		if err == nil {
+			ip := net.ParseIP(ipStr)
+			if ip != nil && !ip.IsGlobalUnicast() {
+				return
+			}
+		}
+
+		return c.Control(func(fd uintptr) {
+			switch network {
+			case "tcp4", "udp4":
+				syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_MARK, mark)
+			case "tcp6", "udp6":
+				syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_MARK, mark)
+			}
+		})
+	}
+}