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)
 }