Do not resolve remote link address at transport layer

Link address resolution is performed at the link layer (if required) so
we can defer it from the transport layer. When link resolution is
required, packets will be queued and sent once link resolution
completes. If link resolution fails, the transport layer will receive a
control message indicating that the stack failed to route the packet.

tcpip.Endpoint.Write no longer returns a channel now that writes do not
wait for link resolution at the transport layer.

tcpip.ErrNoLinkAddress is no longer used so it is removed.

Removed calls to stack.Route.ResolveWith from the transport layer so
that link resolution is performed when a route is created in response
to an incoming packet (e.g. to complete TCP handshakes or send a RST).

Tests:
- integration_test.TestForwarding
- integration_test.TestTCPLinkResolutionFailure

Fixes #4458

RELNOTES: n/a
PiperOrigin-RevId: 351684158

1 files changed, 1 insertions, 11 deletions

diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index f798056c0..002ddaf67 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -104,7 +104,6 @@ var (
 	ErrConnectionAborted         = &Error{msg: "connection aborted"}
 	ErrNoSuchFile                = &Error{msg: "no such file"}
 	ErrInvalidOptionValue        = &Error{msg: "invalid option value specified"}
-	ErrNoLinkAddress             = &Error{msg: "no remote link address"}
 	ErrBadAddress                = &Error{msg: "bad address"}
 	ErrNetworkUnreachable        = &Error{msg: "network is unreachable"}
 	ErrMessageTooLong            = &Error{msg: "message too long"}
@@ -154,7 +153,6 @@ func StringToError(s string) *Error {
 			ErrConnectionAborted,
 			ErrNoSuchFile,
 			ErrInvalidOptionValue,
-			ErrNoLinkAddress,
 			ErrBadAddress,
 			ErrNetworkUnreachable,
 			ErrMessageTooLong,
@@ -640,12 +638,7 @@ type Endpoint interface {
 	// stream (TCP) Endpoints may return partial writes, and even then only
 	// in the case where writing additional data would block. Other Endpoints
 	// will either write the entire message or return an error.
-	//
-	// For UDP and Ping sockets if address resolution is required,
-	// ErrNoLinkAddress and a notification channel is returned for the caller to
-	// block. Channel is closed once address resolution is complete (success or
-	// not). The channel is only non-nil in this case.
-	Write(Payloader, WriteOptions) (int64, <-chan struct{}, *Error)
+	Write(Payloader, WriteOptions) (int64, *Error)
 
 	// Connect connects the endpoint to its peer. Specifying a NIC is
 	// optional.
@@ -1784,9 +1777,6 @@ type SendErrors struct {
 
 	// NoRoute is the number of times we failed to resolve IP route.
 	NoRoute StatCounter
-
-	// NoLinkAddr is the number of times we failed to resolve ARP.
-	NoLinkAddr StatCounter
 }
 
 // ReadErrors collects segment read errors from an endpoint read call.