fqdn proxy: add transparent socket options to IPFamily struct

This commit adds the transparent socket options to the IPFamily
struct. This way it can be used in the respective functions.

Signed-off-by: Marco Hofstetter <marco.hofstetter@isovalent.com>

pkg/fqdn/dnsproxy/udp.go

@@ -75,23 +75,11 @@ type sessionUDP struct {
 // IP(V6)_RECVORIGDSTADDR tells the kernel to pass the original destination address/port on recvmsg
 // By design, a socket of a DNS Server can only receive IPv4 or IPv6 traffic.
 func transparentSetsockopt(fd int, ipFamily ipfamily.IPFamily) error {
-	switch ipFamily {
-	case ipfamily.IPv4():
-		if err := unix.SetsockoptInt(fd, unix.SOL_IP, unix.IP_TRANSPARENT, 1); err != nil {
-			return fmt.Errorf("setsockopt(IP_TRANSPARENT) failed: %w", err)
-		}
-		if err := unix.SetsockoptInt(fd, unix.SOL_IP, unix.IP_RECVORIGDSTADDR, 1); err != nil {
-			return fmt.Errorf("setsockopt(IP_RECVORIGDSTADDR) failed: %w", err)
-		}
-	case ipfamily.IPv6():
-		if err := unix.SetsockoptInt(fd, unix.SOL_IPV6, unix.IPV6_TRANSPARENT, 1); err != nil {
-			return fmt.Errorf("setsockopt(IPV6_TRANSPARENT) failed: %w", err)
-		}
-		if err := unix.SetsockoptInt(fd, unix.SOL_IPV6, unix.IPV6_RECVORIGDSTADDR, 1); err != nil {
-			return fmt.Errorf("setsockopt(IPV6_RECVORIGDSTADDR) failed: %w", err)
-		}
-	default:
-		return fmt.Errorf("unknown ipfamily: %s", ipFamily.Name)
+	if err := unix.SetsockoptInt(fd, ipFamily.SocketOptsFamily, ipFamily.SocketOptsTransparent, 1); err != nil {
+		return fmt.Errorf("setsockopt(IP_TRANSPARENT) for %s failed: %w", ipFamily.Name, err)
+	}
+	if err := unix.SetsockoptInt(fd, ipFamily.SocketOptsFamily, ipFamily.SocketOptsRecvOrigDstAddr, 1); err != nil {
+		return fmt.Errorf("setsockopt(IP_RECVORIGDSTADDR) for %s failed: %w", ipFamily.Name, err)
 	}
 
 	return nil

pkg/fqdn/proxy/ipfamily/ipfamily.go

@@ -3,11 +3,17 @@
 
 package ipfamily
 
+import "golang.org/x/sys/unix"
+
 type IPFamily struct {
 	Name       string
 	UDPAddress string
 	TCPAddress string
 	Localhost  string
+
+	SocketOptsFamily          int
+	SocketOptsTransparent     int
+	SocketOptsRecvOrigDstAddr int
 }
 
 func IPv4() IPFamily {
@@ -16,6 +22,10 @@ func IPv4() IPFamily {
 		UDPAddress: "udp4",
 		TCPAddress: "tcp4",
 		Localhost:  "127.0.0.1",
+
+		SocketOptsFamily:          unix.SOL_IP,
+		SocketOptsTransparent:     unix.IP_TRANSPARENT,
+		SocketOptsRecvOrigDstAddr: unix.IP_RECVORIGDSTADDR,
 	}
 }
 
@@ -25,5 +35,9 @@ func IPv6() IPFamily {
 		UDPAddress: "udp6",
 		TCPAddress: "tcp6",
 		Localhost:  "::1",
+
+		SocketOptsFamily:          unix.SOL_IPV6,
+		SocketOptsTransparent:     unix.IPV6_TRANSPARENT,
+		SocketOptsRecvOrigDstAddr: unix.IPV6_RECVORIGDSTADDR,
 	}
 }