Change tcpip.Error to an interface

This makes it possible to add data to types that implement tcpip.Error.
ErrBadLinkEndpoint is removed as it is unused.

PiperOrigin-RevId: 354437314

2 files changed, 21 insertions, 19 deletions

diff --git a/pkg/tcpip/adapters/gonet/gonet.go b/pkg/tcpip/adapters/gonet/gonet.go
index 7c7495c30..c188aaa18 100644
--- a/pkg/tcpip/adapters/gonet/gonet.go
+++ b/pkg/tcpip/adapters/gonet/gonet.go
@@ -248,7 +248,7 @@ func NewTCPConn(wq *waiter.Queue, ep tcpip.Endpoint) *TCPConn {
 func (l *TCPListener) Accept() (net.Conn, error) {
 	n, wq, err := l.ep.Accept(nil)
 
-	if err == tcpip.ErrWouldBlock {
+	if _, ok := err.(*tcpip.ErrWouldBlock); ok {
 		// Create wait queue entry that notifies a channel.
 		waitEntry, notifyCh := waiter.NewChannelEntry(nil)
 		l.wq.EventRegister(&waitEntry, waiter.EventIn)
@@ -257,7 +257,7 @@ func (l *TCPListener) Accept() (net.Conn, error) {
 		for {
 			n, wq, err = l.ep.Accept(nil)
 
-			if err != tcpip.ErrWouldBlock {
+			if _, ok := err.(*tcpip.ErrWouldBlock); !ok {
 				break
 			}
 
@@ -298,14 +298,14 @@ func commonRead(b []byte, ep tcpip.Endpoint, wq *waiter.Queue, deadline <-chan s
 	opts := tcpip.ReadOptions{NeedRemoteAddr: addr != nil}
 	res, err := ep.Read(&w, opts)
 
-	if err == tcpip.ErrWouldBlock {
+	if _, ok := err.(*tcpip.ErrWouldBlock); ok {
 		// Create wait queue entry that notifies a channel.
 		waitEntry, notifyCh := waiter.NewChannelEntry(nil)
 		wq.EventRegister(&waitEntry, waiter.EventIn)
 		defer wq.EventUnregister(&waitEntry)
 		for {
 			res, err = ep.Read(&w, opts)
-			if err != tcpip.ErrWouldBlock {
+			if _, ok := err.(*tcpip.ErrWouldBlock); !ok {
 				break
 			}
 			select {
@@ -316,7 +316,7 @@ func commonRead(b []byte, ep tcpip.Endpoint, wq *waiter.Queue, deadline <-chan s
 		}
 	}
 
-	if err == tcpip.ErrClosedForReceive {
+	if _, ok := err.(*tcpip.ErrClosedForReceive); ok {
 		return 0, io.EOF
 	}
 
@@ -356,7 +356,7 @@ func (c *TCPConn) Write(b []byte) (int, error) {
 	}
 
 	// We must handle two soft failure conditions simultaneously:
-	//  1. Write may write nothing and return tcpip.ErrWouldBlock.
+	//  1. Write may write nothing and return *tcpip.ErrWouldBlock.
 	//     If this happens, we need to register for notifications if we have
 	//     not already and wait to try again.
 	//  2. Write may write fewer than the full number of bytes and return
@@ -376,9 +376,9 @@ func (c *TCPConn) Write(b []byte) (int, error) {
 		r.Reset(b[nbytes:])
 		n, err := c.ep.Write(&r, tcpip.WriteOptions{})
 		nbytes += int(n)
-		switch err {
+		switch err.(type) {
 		case nil:
-		case tcpip.ErrWouldBlock:
+		case *tcpip.ErrWouldBlock:
 			if ch == nil {
 				entry, ch = waiter.NewChannelEntry(nil)
 
@@ -495,7 +495,7 @@ func DialContextTCP(ctx context.Context, s *stack.Stack, addr tcpip.FullAddress,
 	}
 
 	err = ep.Connect(addr)
-	if err == tcpip.ErrConnectStarted {
+	if _, ok := err.(*tcpip.ErrConnectStarted); ok {
 		select {
 		case <-ctx.Done():
 			ep.Close()
@@ -649,7 +649,7 @@ func (c *UDPConn) WriteTo(b []byte, addr net.Addr) (int, error) {
 	var r bytes.Reader
 	r.Reset(b)
 	n, err := c.ep.Write(&r, writeOptions)
-	if err == tcpip.ErrWouldBlock {
+	if _, ok := err.(*tcpip.ErrWouldBlock); ok {
 		// Create wait queue entry that notifies a channel.
 		waitEntry, notifyCh := waiter.NewChannelEntry(nil)
 		c.wq.EventRegister(&waitEntry, waiter.EventOut)
@@ -662,7 +662,7 @@ func (c *UDPConn) WriteTo(b []byte, addr net.Addr) (int, error) {
 			}
 
 			n, err = c.ep.Write(&r, writeOptions)
-			if err != tcpip.ErrWouldBlock {
+			if _, ok := err.(*tcpip.ErrWouldBlock); !ok {
 				break
 			}
 		}
diff --git a/pkg/tcpip/adapters/gonet/gonet_test.go b/pkg/tcpip/adapters/gonet/gonet_test.go
index b196324c7..2b3ea4bdf 100644
--- a/pkg/tcpip/adapters/gonet/gonet_test.go
+++ b/pkg/tcpip/adapters/gonet/gonet_test.go
@@ -58,7 +58,7 @@ func TestTimeouts(t *testing.T) {
 	}
 }
 
-func newLoopbackStack() (*stack.Stack, *tcpip.Error) {
+func newLoopbackStack() (*stack.Stack, tcpip.Error) {
 	// Create the stack and add a NIC.
 	s := stack.New(stack.Options{
 		NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
@@ -94,7 +94,7 @@ type testConnection struct {
 	ep tcpip.Endpoint
 }
 
-func connect(s *stack.Stack, addr tcpip.FullAddress) (*testConnection, *tcpip.Error) {
+func connect(s *stack.Stack, addr tcpip.FullAddress) (*testConnection, tcpip.Error) {
 	wq := &waiter.Queue{}
 	ep, err := s.NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, wq)
 	if err != nil {
@@ -105,7 +105,7 @@ func connect(s *stack.Stack, addr tcpip.FullAddress) (*testConnection, *tcpip.Er
 	wq.EventRegister(&entry, waiter.EventOut)
 
 	err = ep.Connect(addr)
-	if err == tcpip.ErrConnectStarted {
+	if _, ok := err.(*tcpip.ErrConnectStarted); ok {
 		<-ch
 		err = ep.LastError()
 	}
@@ -660,11 +660,13 @@ func TestTCPDialError(t *testing.T) {
 	ip := tcpip.Address(net.IPv4(169, 254, 10, 1).To4())
 	addr := tcpip.FullAddress{NICID, ip, 11211}
 
-	_, err := DialTCP(s, addr, ipv4.ProtocolNumber)
-	got, ok := err.(*net.OpError)
-	want := tcpip.ErrNoRoute
-	if !ok || got.Err.Error() != want.String() {
-		t.Errorf("Got DialTCP() = %v, want = %v", err, tcpip.ErrNoRoute)
+	switch _, err := DialTCP(s, addr, ipv4.ProtocolNumber); err := err.(type) {
+	case *net.OpError:
+		if err.Err.Error() != (&tcpip.ErrNoRoute{}).String() {
+			t.Errorf("got DialTCP() = %s, want = %s", err, &tcpip.ErrNoRoute{})
+		}
+	default:
+		t.Errorf("got DialTCP(...) = %v, want %s", err, &tcpip.ErrNoRoute{})
 	}
 }