Do not cache remote link address in Route

...unless explicitly requested via ResolveWith.

Remove cancelled channels from pending packets as we can use the link
resolution channel in a FIFO to limit the number of maximum pending
resolutions we should queue packets for.

This change also defers starting the goroutine that handles link
resolution completion to when link resolution succeeds, fails or
gets cancelled due to the max number of pending resolutions being
reached.

Fixes #751.

PiperOrigin-RevId: 353130577

1 files changed, 13 insertions, 7 deletions

diff --git a/pkg/tcpip/stack/linkaddrcache_test.go b/pkg/tcpip/stack/linkaddrcache_test.go
index 8c35067c6..88fbbf3fe 100644
--- a/pkg/tcpip/stack/linkaddrcache_test.go
+++ b/pkg/tcpip/stack/linkaddrcache_test.go
@@ -93,8 +93,14 @@ func getBlocking(c *linkAddrCache, addr tcpip.Address, linkRes LinkAddressResolv
 	}
 }
 
+func newEmptyNIC() *NIC {
+	n := &NIC{}
+	n.linkResQueue.init(n)
+	return n
+}
+
 func TestCacheOverflow(t *testing.T) {
-	c := newLinkAddrCache(1<<63-1, 1*time.Second, 3)
+	c := newLinkAddrCache(newEmptyNIC(), 1<<63-1, 1*time.Second, 3)
 	for i := len(testAddrs) - 1; i >= 0; i-- {
 		e := testAddrs[i]
 		c.AddLinkAddress(e.addr, e.linkAddr)
@@ -129,7 +135,7 @@ func TestCacheOverflow(t *testing.T) {
 }
 
 func TestCacheConcurrent(t *testing.T) {
-	c := newLinkAddrCache(1<<63-1, 1*time.Second, 3)
+	c := newLinkAddrCache(newEmptyNIC(), 1<<63-1, 1*time.Second, 3)
 	linkRes := &testLinkAddressResolver{cache: c}
 
 	var wg sync.WaitGroup
@@ -165,7 +171,7 @@ func TestCacheConcurrent(t *testing.T) {
 }
 
 func TestCacheAgeLimit(t *testing.T) {
-	c := newLinkAddrCache(1*time.Millisecond, 1*time.Second, 3)
+	c := newLinkAddrCache(newEmptyNIC(), 1*time.Millisecond, 1*time.Second, 3)
 	linkRes := &testLinkAddressResolver{cache: c}
 
 	e := testAddrs[0]
@@ -177,7 +183,7 @@ func TestCacheAgeLimit(t *testing.T) {
 }
 
 func TestCacheReplace(t *testing.T) {
-	c := newLinkAddrCache(1<<63-1, 1*time.Second, 3)
+	c := newLinkAddrCache(newEmptyNIC(), 1<<63-1, 1*time.Second, 3)
 	e := testAddrs[0]
 	l2 := e.linkAddr + "2"
 	c.AddLinkAddress(e.addr, e.linkAddr)
@@ -206,7 +212,7 @@ func TestCacheResolution(t *testing.T) {
 	//
 	// Using a large resolution timeout decreases the probability of experiencing
 	// this race condition and does not affect how long this test takes to run.
-	c := newLinkAddrCache(1<<63-1, math.MaxInt64, 1)
+	c := newLinkAddrCache(newEmptyNIC(), 1<<63-1, math.MaxInt64, 1)
 	linkRes := &testLinkAddressResolver{cache: c}
 	for i, ta := range testAddrs {
 		got, err := getBlocking(c, ta.addr, linkRes)
@@ -232,7 +238,7 @@ func TestCacheResolution(t *testing.T) {
 }
 
 func TestCacheResolutionFailed(t *testing.T) {
-	c := newLinkAddrCache(1<<63-1, 10*time.Millisecond, 5)
+	c := newLinkAddrCache(newEmptyNIC(), 1<<63-1, 10*time.Millisecond, 5)
 	linkRes := &testLinkAddressResolver{cache: c}
 
 	var requestCount uint32
@@ -265,7 +271,7 @@ func TestCacheResolutionFailed(t *testing.T) {
 func TestCacheResolutionTimeout(t *testing.T) {
 	resolverDelay := 500 * time.Millisecond
 	expiration := resolverDelay / 10
-	c := newLinkAddrCache(expiration, 1*time.Millisecond, 3)
+	c := newLinkAddrCache(newEmptyNIC(), expiration, 1*time.Millisecond, 3)
 	linkRes := &testLinkAddressResolver{cache: c, delay: resolverDelay}
 
 	e := testAddrs[0]