feat: add func to shorten strings, deprecate old hash funcs (#145)

* feat: add func to shorten strings, deprecate old hash funcs

* deprecate K8sNameUUID

* typo

Author: ValentinGerlach

pkg/controller/hash.go

@@ -13,12 +13,13 @@ import (
 )
 
 var (
-	ErrInvalidNames = errors.New("list of names must not be empty and contain at least one non-empty string")
+	ErrInvalidNames   = errors.New("list of names must not be empty and contain at least one non-empty string")
+	ErrMaxLenTooSmall = errors.New("maxLen must be greater than 10")
 )
 
-// Version8UUID creates a new UUID (version 8) from a byte slice. Returns an error if the slice does not have a length of 16. The bytes are copied from the slice.
+// version8UUID creates a new UUID (version 8) from a byte slice. Returns an error if the slice does not have a length of 16. The bytes are copied from the slice.
 // The bits 48-51 and 64-65 are modified to make the output recognizable as a version 8 UUID, so only 122 out of 128 bits from the input data will be kept.
-func Version8UUID(data []byte) (uuid.UUID, error) {
+func version8UUID(data []byte) (uuid.UUID, error) {
 	if len(data) != 16 {
 		return uuid.Nil, fmt.Errorf("invalid data (got %d bytes)", len(data))
 	}
@@ -40,14 +41,15 @@ func Version8UUID(data []byte) (uuid.UUID, error) {
 // K8sNameUUID takes any number of string arguments and computes a hash out of it, which is then formatted as a version 8 UUID.
 // The arguments are joined with '/' before being hashed.
 // Returns an error if the list of ids is empty or contains only empty strings.
+// Deprecated: Use NameHashSHAKE128Base32 instead.
 func K8sNameUUID(names ...string) (string, error) {
 	if err := validateIDs(names); err != nil {
 		return "", err
 	}
 
 	name := strings.Join(names, "/")
 	hash := sha3.SumSHAKE128([]byte(name), 16)
-	u, err := Version8UUID(hash)
+	u, err := version8UUID(hash)
 
 	return u.String(), err
 }
@@ -64,6 +66,7 @@ func validateIDs(names []string) error {
 
 // K8sNameUUIDUnsafe works like K8sNameUUID, but panics instead of returning an error.
 // This should only be used in places where the input is guaranteed to be valid.
+// Deprecated: Use NameHashSHAKE128Base32 instead.
 func K8sNameUUIDUnsafe(names ...string) string {
 	uuid, err := K8sNameUUID(names...)
 	if err != nil {
@@ -74,6 +77,7 @@ func K8sNameUUIDUnsafe(names ...string) string {
 
 // K8sObjectUUID takes a client object and computes a hash out of the namespace and name, which is then formatted as a version 8 UUID.
 // An empty namespace will be replaced by "default".
+// Deprecated: Use ObjectHashSHAKE128Base32 instead.
 func K8sObjectUUID(obj client.Object) (string, error) {
 	name, namespace := obj.GetName(), obj.GetNamespace()
 	if namespace == "" {
@@ -84,6 +88,7 @@ func K8sObjectUUID(obj client.Object) (string, error) {
 
 // K8sObjectUUIDUnsafe works like K8sObjectUUID, but panics instead of returning an error.
 // This should only be used in places where the input is guaranteed to be valid.
+// Deprecated: Use ObjectHashSHAKE128Base32 instead.
 func K8sObjectUUIDUnsafe(obj client.Object) string {
 	uuid, err := K8sObjectUUID(obj)
 	if err != nil {
@@ -113,3 +118,21 @@ func ObjectHashSHAKE128Base32(obj client.Object) string {
 	}
 	return NameHashSHAKE128Base32(namespace, name)
 }
+
+// ShortenToXCharacters shortens the input string if it exceeds maxLen.
+// It uses NameHashSHAKE128Base32 to generate a hash which will replace the last few characters.
+func ShortenToXCharacters(input string, maxLen int) (string, error) {
+	if len(input) <= maxLen {
+		return input, nil
+	}
+
+	hash := NameHashSHAKE128Base32(input)
+	suffix := fmt.Sprintf("--%s", hash)
+	trimLength := maxLen - len(suffix)
+
+	if trimLength <= 0 {
+		return "", ErrMaxLenTooSmall
+	}
+
+	return input[:trimLength] + suffix, nil
+}

pkg/controller/hash_test.go

@@ -44,7 +44,7 @@ func Test_Version8UUID(t *testing.T) {
 	}
 	for _, tC := range testCases {
 		t.Run(tC.desc, func(t *testing.T) {
-			u, err := Version8UUID(tC.data)
+			u, err := version8UUID(tC.data)
 			if tC.expectedErr == nil {
 				assert.NoError(t, err)
 				assert.Equal(t, uuid.Version(8), u.Version(), "unexpected version")
@@ -189,3 +189,49 @@ func Test_ObjectHashSHAKE128Base32(t *testing.T) {
 		})
 	}
 }
+
+func Test_ShortenToXCharacters(t *testing.T) {
+	testCases := []struct {
+		desc        string
+		input       string
+		maxLen      int
+		expected    string
+		expectedErr error
+	}{
+		{
+			desc:     "short string",
+			input:    "short",
+			expected: "short",
+			maxLen:   100,
+		},
+		{
+			desc:     "short string to trim",
+			input:    "short1234567",
+			expected: "s--j5gore3p",
+			maxLen:   11,
+		},
+		{
+			desc:        "maxLen too small",
+			input:       "shorter1234",
+			maxLen:      10,
+			expectedErr: ErrMaxLenTooSmall,
+		},
+		{
+			desc:     "long string",
+			input:    "this-is-a-very-a-very-a-very-long-string-that-is-over-63-characters",
+			expected: "this-is-a-very-a-very-a-very-long-string-that-is-over--6reoyp5o",
+			maxLen:   63,
+		},
+	}
+	for _, tC := range testCases {
+		t.Run(tC.desc, func(t *testing.T) {
+			actual, err := ShortenToXCharacters(tC.input, tC.maxLen)
+			if tC.expectedErr == nil {
+				assert.Equal(t, tC.expected, actual)
+				assert.LessOrEqual(t, len(actual), tC.maxLen)
+			} else {
+				assert.Equal(t, tC.expectedErr, err)
+			}
+		})
+	}
+}

pkg/controller/utils.go

@@ -15,6 +15,7 @@ const (
 
 // K8sNameHash takes any number of string arguments and computes a hash out of it, which is then base32-encoded to be a valid DNS1123Subdomain k8s resource name
 // The arguments are joined with '/' before being hashed.
+// Deprecated: Use NameHashSHAKE128Base32 instead.
 func K8sNameHash(ids ...string) string {
 	name := strings.Join(ids, "/")
 	// since we are not worried about length-extension attacks (in fact we are not even using hashing for