Fix broken hdrincl test

Fixes #3159.

PiperOrigin-RevId: 379814096

pkg/tcpip/transport/raw/endpoint.go

@@ -286,26 +286,6 @@ func (e *endpoint) write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, tcp
 			return nil, nil, nil, &tcpip.ErrBadBuffer{}
 		}
 
-		// If this is an unassociated socket and callee provided a nonzero
-		// destination address, route using that address.
-		if e.ops.GetHeaderIncluded() {
-			ip := header.IPv4(payloadBytes)
-			if !ip.IsValid(len(payloadBytes)) {
-				return nil, nil, nil, &tcpip.ErrInvalidOptionValue{}
-			}
-			dstAddr := ip.DestinationAddress()
-			// Update dstAddr with the address in the IP header, unless
-			// opts.To is set (e.g. if sendto specifies a specific
-			// address).
-			if dstAddr != tcpip.Address([]byte{0, 0, 0, 0}) && opts.To == nil {
-				opts.To = &tcpip.FullAddress{
-					NIC:  0,       // NIC is unset.
-					Addr: dstAddr, // The address from the payload.
-					Port: 0,       // There are no ports here.
-				}
-			}
-		}
-
 		// Did the user caller provide a destination? If not, use the connected
 		// destination.
 		if opts.To == nil {

test/syscalls/linux/raw_socket_hdrincl.cc

@@ -177,11 +177,10 @@ TEST_F(RawHDRINCL, ConnectToLoopback) {
               SyscallSucceeds());
 }
 
-// FIXME(gvisor.dev/issue/3159): Test currently flaky.
-TEST_F(RawHDRINCL, DISABLED_SendWithoutConnectSucceeds) {
+TEST_F(RawHDRINCL, SendWithoutConnectFails) {
   struct iphdr hdr = LoopbackHeader();
   ASSERT_THAT(send(socket_, &hdr, sizeof(hdr), 0),
-              SyscallSucceedsWithValue(sizeof(hdr)));
+              SyscallFailsWithErrno(EDESTADDRREQ));
 }
 
 // HDRINCL implies write-only. Verify that we can't read a packet sent to