pkg/utils: use name+id for hash and extend tests

pkg/utils/utils.go

@@ -5,16 +5,15 @@ import (
 	"fmt"
 )
 
-// 29 - len('CNI') - 2*len('-')
-const maxNameLen = 16
+const MaxChainLength = 29 - len("CNI-")
 
 // Generates a chain name to be used with iptables.
 // Ensures that the generated name is less than
 // 29 chars in length
 func FormatChainName(name string, id string) string {
-	h := sha512.Sum512([]byte(id))
-	if len(name) > maxNameLen {
-		return fmt.Sprintf("CNI-%s-%x", name[:len(name)-maxNameLen], h[:8])
+	chain := fmt.Sprintf("%x", sha512.Sum512([]byte(name+id)))
+	if len(chain) > MaxChainLength {
+		chain = chain[:MaxChainLength]
 	}
-	return fmt.Sprintf("CNI-%s-%x", name, h[:8])
+	return fmt.Sprintf("CNI-%s", chain)
 }

pkg/utils/utils_test.go

@@ -6,13 +6,34 @@ import (
 )
 
 var _ = Describe("Utils", func() {
-	It("should format a short name", func() {
+	It("must format a short name", func() {
 		chain := FormatChainName("test", "1234")
-		Expect(chain).To(Equal("CNI-test-d404559f602eab6f"))
+		Expect(len(chain) == 29).To(Equal(true))
+		Expect(chain).To(Equal("CNI-2bbe0c48b91a7d1b8a6753a8b"))
 	})
 
-	It("should truncate a long name", func() {
+	It("must truncate a long name", func() {
 		chain := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
-		Expect(chain).To(Equal("CNI-testalongnamethat-d404559f602eab6f"))
+		Expect(len(chain) == 29).To(Equal(true))
+		Expect(chain).To(Equal("CNI-374f33fe84ab0ed84dcdebe38"))
 	})
+
+	It("must be predictable", func() {
+		chain1 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
+		chain2 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
+		Expect(len(chain1) == 29).To(Equal(true))
+		Expect(len(chain2) == 29).To(Equal(true))
+		Expect(chain1).To(Equal(chain2))
+	})
+
+	It("must change when a character changes", func() {
+		chain1 := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
+		chain2 := FormatChainName("testalongnamethatdoesnotmakesense", "1235")
+		Expect(len(chain1) == 29).To(Equal(true))
+		Expect(len(chain2) == 29).To(Equal(true))
+		Expect(chain1).To(Equal("CNI-374f33fe84ab0ed84dcdebe38"))
+		Expect(chain2).NotTo(Equal("CNI-374f33fe84ab0ed84dcdebe38"))
+		Expect(chain1).NotTo(Equal(chain2))
+	})
+
 })