ipam: Test rejection of overlapping pool requests

TestOverlappingRequests checks that pool requests which are supersets or
subsets of existing allocations, and those which overlap with existing
allocations at the beginning or the end.

Multiple allocation is now tested by TestOverlappingRequests, so
TestDoublePoolRelease only needs to test double releasing.

Signed-off-by: Euan Harris <euan.harris@docker.com>

libnetwork/ipam/allocator_test.go

@@ -286,28 +286,17 @@ func TestAddSubnets(t *testing.T) {
 // been released raises an error.
 func TestDoublePoolRelease(t *testing.T) {
 	for _, store := range []bool{false, true} {
-		for _, repeats := range []int{0, 1, 10} {
-			a, err := getAllocator(store)
-			assert.NoError(t, err)
+		a, err := getAllocator(store)
+		assert.NoError(t, err)
 
-			// Request initial pool allocation
-			pid0, _, _, err := a.RequestPool(localAddressSpace, "10.0.0.0/8", "", nil, false)
-			assert.NoError(t, err)
+		pid0, _, _, err := a.RequestPool(localAddressSpace, "10.0.0.0/8", "", nil, false)
+		assert.NoError(t, err)
 
-			// Re-request the same pool
-			for i := 0; i < repeats; i++ {
-				_, _, _, err := a.RequestPool(localAddressSpace, "10.0.0.0/8", "", nil, false)
-				assert.Error(t, err)
-			}
+		err = a.ReleasePool(pid0)
+		assert.NoError(t, err)
 
-			// Release the initial request
-			err = a.ReleasePool(pid0)
-			assert.NoError(t, err)
-
-			// Releasing again fails
-			err = a.ReleasePool(pid0)
-			assert.Error(t, err)
-		}
+		err = a.ReleasePool(pid0)
+		assert.Error(t, err)
 	}
 }
 
@@ -987,6 +976,85 @@ func TestRequest(t *testing.T) {
 	}
 }
 
+// TestOverlappingRequests tests that overlapping subnets cannot be allocated.
+// Requests for subnets which are supersets or subsets of existing allocations,
+// or which overlap at the beginning or end, should not be permitted.
+func TestOverlappingRequests(t *testing.T) {
+	input := []struct {
+		environment []string
+		subnet      string
+		ok          bool
+	}{
+		// IPv4
+		// Previously allocated network does not overlap with request
+		{[]string{"10.0.0.0/8"}, "11.0.0.0/8", true},
+		{[]string{"74.0.0.0/7"}, "9.111.99.72/30", true},
+		{[]string{"110.192.0.0/10"}, "16.0.0.0/10", true},
+
+		// Previously allocated network entirely contains request
+		{[]string{"10.0.0.0/8"}, "10.0.0.0/8", false}, // exact overlap
+		{[]string{"0.0.0.0/1"}, "16.182.0.0/15", false},
+		{[]string{"16.0.0.0/4"}, "17.11.66.0/23", false},
+
+		// Previously allocated network overlaps beginning of request
+		{[]string{"0.0.0.0/1"}, "0.0.0.0/0", false},
+		{[]string{"64.0.0.0/6"}, "64.0.0.0/3", false},
+		{[]string{"112.0.0.0/6"}, "112.0.0.0/4", false},
+
+		// Previously allocated network overlaps end of request
+		{[]string{"96.0.0.0/3"}, "0.0.0.0/1", false},
+		{[]string{"192.0.0.0/2"}, "128.0.0.0/1", false},
+		{[]string{"95.0.0.0/8"}, "92.0.0.0/6", false},
+
+		// Previously allocated network entirely contained within request
+		{[]string{"10.0.0.0/8"}, "10.0.0.0/6", false}, // non-canonical
+		{[]string{"10.0.0.0/8"}, "8.0.0.0/6", false},  // canonical
+		{[]string{"25.173.144.0/20"}, "0.0.0.0/0", false},
+
+		// IPv6
+		// Previously allocated network entirely contains request
+		{[]string{"::/0"}, "f656:3484:c878:a05:e540:a6ed:4d70:3740/123", false},
+		{[]string{"8000::/1"}, "8fe8:e7c4:5779::/49", false},
+		{[]string{"f000::/4"}, "ffc7:6000::/19", false},
+
+		// Previously allocated network overlaps beginning of request
+		{[]string{"::/2"}, "::/0", false},
+		{[]string{"::/3"}, "::/1", false},
+		{[]string{"::/6"}, "::/5", false},
+
+		// Previously allocated network overlaps end of request
+		{[]string{"c000::/2"}, "8000::/1", false},
+		{[]string{"7c00::/6"}, "::/1", false},
+		{[]string{"cf80::/9"}, "c000::/4", false},
+
+		// Previously allocated network entirely contained within request
+		{[]string{"ff77:93f8::/29"}, "::/0", false},
+		{[]string{"9287:2e20:5134:fab6:9061:a0c6:bfe3:9400/119"}, "8000::/1", false},
+		{[]string{"3ea1:bfa9:8691:d1c6:8c46:519b:db6d:e700/120"}, "3000::/4", false},
+	}
+
+	for _, store := range []bool{false, true} {
+		for _, tc := range input {
+			a, err := getAllocator(store)
+			assert.NoError(t, err)
+
+			// Set up some existing allocations.  This should always succeed.
+			for _, env := range tc.environment {
+				_, _, _, err = a.RequestPool(localAddressSpace, env, "", nil, false)
+				assert.NoError(t, err)
+			}
+
+			// Make the test allocation.
+			_, _, _, err = a.RequestPool(localAddressSpace, tc.subnet, "", nil, false)
+			if tc.ok {
+				assert.NoError(t, err)
+			} else {
+				assert.Error(t, err)
+			}
+		}
+	}
+}
+
 func TestRelease(t *testing.T) {
 	var (
 		subnet = "192.168.0.0/23"