fix(netx): make sure we save quic udp conn events (#423)

https://github.com/ooni/probe-cli/pull/421 was wrong because we need
a more rich interface for quic-go to call ReadMsgUDP.

With this commit, we use such an interface: OOBCapablePacketConn.

Still part of https://github.com/ooni/probe/issues/1505.

internal/netxmocks/quic.go

@@ -4,19 +4,19 @@ import (
 	"context"
 	"crypto/tls"
 	"net"
+	"syscall"
 	"time"
 
 	"github.com/lucas-clemente/quic-go"
-	"github.com/ooni/probe-cli/v3/internal/quicx"
 )
 
 // QUICListener is a mockable netxlite.QUICListener.
 type QUICListener struct {
-	MockListen func(addr *net.UDPAddr) (quicx.UDPConn, error)
+	MockListen func(addr *net.UDPAddr) (quic.OOBCapablePacketConn, error)
 }
 
 // Listen calls MockListen.
-func (ql *QUICListener) Listen(addr *net.UDPAddr) (quicx.UDPConn, error) {
+func (ql *QUICListener) Listen(addr *net.UDPAddr) (quic.OOBCapablePacketConn, error) {
 	return ql.MockListen(addr)
 }
 
@@ -140,9 +140,11 @@ type QUICUDPConn struct {
 	MockSetReadDeadline  func(t time.Time) error
 	MockSetWriteDeadline func(t time.Time) error
 	MockReadFrom         func(p []byte) (n int, addr net.Addr, err error)
+	MockSyscallConn      func() (syscall.RawConn, error)
+	MockWriteMsgUDP      func(b, oob []byte, addr *net.UDPAddr) (n, oobn int, err error)
 }
 
-var _ net.PacketConn = &QUICUDPConn{}
+var _ quic.OOBCapablePacketConn = &QUICUDPConn{}
 
 // WriteTo calls MockWriteTo.
 func (c *QUICUDPConn) WriteTo(p []byte, addr net.Addr) (int, error) {
@@ -188,3 +190,13 @@ func (c *QUICUDPConn) SetWriteDeadline(t time.Time) error {
 func (c *QUICUDPConn) ReadFrom(b []byte) (int, net.Addr, error) {
 	return c.MockReadFrom(b)
 }
+
+// SyscallConn calls MockSyscallConn.
+func (c *QUICUDPConn) SyscallConn() (syscall.RawConn, error) {
+	return c.MockSyscallConn()
+}
+
+// WriteMsgUDP calls MockReadMsgUDP.
+func (c *QUICUDPConn) WriteMsgUDP(b, oob []byte, addr *net.UDPAddr) (n, oobn int, err error) {
+	return c.MockWriteMsgUDP(b, oob, addr)
+}

internal/netxmocks/quic_test.go

@@ -6,18 +6,18 @@ import (
 	"errors"
 	"net"
 	"reflect"
+	"syscall"
 	"testing"
 	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/lucas-clemente/quic-go"
-	"github.com/ooni/probe-cli/v3/internal/quicx"
 )
 
 func TestQUICListenerListen(t *testing.T) {
 	expected := errors.New("mocked error")
 	ql := &QUICListener{
-		MockListen: func(addr *net.UDPAddr) (quicx.UDPConn, error) {
+		MockListen: func(addr *net.UDPAddr) (quic.OOBCapablePacketConn, error) {
 			return nil, expected
 		},
 	}
@@ -417,3 +417,41 @@ func TestQUICUDPConnReadFrom(t *testing.T) {
 		t.Fatal("expected nil here")
 	}
 }
+
+func TestQUICUDPConnSyscallConn(t *testing.T) {
+	expected := errors.New("mocked error")
+	quc := &QUICUDPConn{
+		MockSyscallConn: func() (syscall.RawConn, error) {
+			return nil, expected
+		},
+	}
+	conn, err := quc.SyscallConn()
+	if !errors.Is(err, expected) {
+		t.Fatal("not the error we expected", err)
+	}
+	if conn != nil {
+		t.Fatal("expected nil here")
+	}
+}
+
+func TestQUICUDPConnWriteMsgUDP(t *testing.T) {
+	expected := errors.New("mocked error")
+	quc := &QUICUDPConn{
+		MockWriteMsgUDP: func(b, oob []byte, addr *net.UDPAddr) (n int, oobn int, err error) {
+			return 0, 0, expected
+		},
+	}
+	b := make([]byte, 128)
+	oob := make([]byte, 128)
+	addr := &net.UDPAddr{}
+	n, oobn, err := quc.WriteMsgUDP(b, oob, addr)
+	if !errors.Is(err, expected) {
+		t.Fatal("not the error we expected", err)
+	}
+	if n != 0 {
+		t.Fatal("expected 0 here")
+	}
+	if oobn != 0 {
+		t.Fatal("expected 0 here")
+	}
+}