From 876105b0cd5c808dfb27b1e8e415680ee1315a9d Mon Sep 17 00:00:00 2001
From: JUN JIE NAN <nanjunjie@gmail.com>
Date: Fri, 11 Feb 2022 17:47:55 +0800
Subject: [PATCH] Exported NKeys Error Enhancement

Make the errors exported outside const instead variable, so that the
users can not change them, and do cleanup to the others return errors
not defined clearly.

Signed-off-by: JUN JIE NAN <nanjunjie@gmail.com>
---
 crc16.go       |  7 -------
 creds_utils.go |  7 +++----
 errors.go      | 38 ++++++++++++++++++++++++++++++++++++++
 main.go        | 18 ------------------
 4 files changed, 41 insertions(+), 29 deletions(-)
 create mode 100644 errors.go

diff --git a/crc16.go b/crc16.go
index c3356cf..fbe38fb 100644
--- a/crc16.go
+++ b/crc16.go
@@ -13,15 +13,8 @@
 
 package nkeys
 
-import (
-	"errors"
-)
-
 // An implementation of crc16 according to CCITT standards for XMODEM.
 
-// ErrInvalidChecksum indicates a failed verification.
-var ErrInvalidChecksum = errors.New("nkeys: invalid checksum")
-
 var crc16tab = [256]uint16{
 	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
 	0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
diff --git a/creds_utils.go b/creds_utils.go
index e1c3d94..c8e3c62 100644
--- a/creds_utils.go
+++ b/creds_utils.go
@@ -2,7 +2,6 @@ package nkeys
 
 import (
 	"bytes"
-	"errors"
 	"regexp"
 )
 
@@ -42,12 +41,12 @@ func ParseDecoratedNKey(contents []byte) (KeyPair, error) {
 		}
 	}
 	if seed == nil {
-		return nil, errors.New("no nkey seed found")
+		return nil, ErrNoSeedFound
 	}
 	if !bytes.HasPrefix(seed, []byte("SO")) &&
 		!bytes.HasPrefix(seed, []byte("SA")) &&
 		!bytes.HasPrefix(seed, []byte("SU")) {
-		return nil, errors.New("doesn't contain a seed nkey")
+		return nil, ErrInvalidNkeySeed
 	}
 	kp, err := FromSeed(seed)
 	if err != nil {
@@ -68,7 +67,7 @@ func ParseDecoratedUserNKey(contents []byte) (KeyPair, error) {
 		return nil, err
 	}
 	if !bytes.HasPrefix(seed, []byte("SU")) {
-		return nil, errors.New("doesn't contain an user seed nkey")
+		return nil, ErrInvalidUserSeed
 	}
 	kp, err := FromSeed(seed)
 	if err != nil {
diff --git a/errors.go b/errors.go
new file mode 100644
index 0000000..798cee4
--- /dev/null
+++ b/errors.go
@@ -0,0 +1,38 @@
+// Copyright 2022 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package nkeys
+
+// Errors
+const (
+	ErrInvalidPrefixByte = nkeysError("nkeys: invalid prefix byte")
+	ErrInvalidKey        = nkeysError("nkeys: invalid key")
+	ErrInvalidPublicKey  = nkeysError("nkeys: invalid public key")
+	ErrInvalidSeedLen    = nkeysError("nkeys: invalid seed length")
+	ErrInvalidSeed       = nkeysError("nkeys: invalid seed")
+	ErrInvalidEncoding   = nkeysError("nkeys: invalid encoded key")
+	ErrInvalidSignature  = nkeysError("nkeys: signature verification failed")
+	ErrCannotSign        = nkeysError("nkeys: can not sign, no private key available")
+	ErrPublicKeyOnly     = nkeysError("nkeys: no seed or private key available")
+	ErrIncompatibleKey   = nkeysError("nkeys: incompatible key")
+	ErrInvalidChecksum   = nkeysError("nkeys: invalid checksum")
+	ErrNoSeedFound       = nkeysError("no nkey seed found")
+	ErrInvalidNkeySeed   = nkeysError("doesn't contain a seed nkey")
+	ErrInvalidUserSeed   = nkeysError("doesn't contain an user seed nkey")
+)
+
+type nkeysError string
+
+func (e nkeysError) Error() string {
+	return string(e)
+}
diff --git a/main.go b/main.go
index 47d01c5..da5c1ec 100644
--- a/main.go
+++ b/main.go
@@ -15,27 +15,9 @@
 // and performs signing and verification.
 package nkeys
 
-import (
-	"errors"
-)
-
 // Version is our current version
 const Version = "0.3.0"
 
-// Errors
-var (
-	ErrInvalidPrefixByte = errors.New("nkeys: invalid prefix byte")
-	ErrInvalidKey        = errors.New("nkeys: invalid key")
-	ErrInvalidPublicKey  = errors.New("nkeys: invalid public key")
-	ErrInvalidSeedLen    = errors.New("nkeys: invalid seed length")
-	ErrInvalidSeed       = errors.New("nkeys: invalid seed")
-	ErrInvalidEncoding   = errors.New("nkeys: invalid encoded key")
-	ErrInvalidSignature  = errors.New("nkeys: signature verification failed")
-	ErrCannotSign        = errors.New("nkeys: can not sign, no private key available")
-	ErrPublicKeyOnly     = errors.New("nkeys: no seed or private key available")
-	ErrIncompatibleKey   = errors.New("nkeys: incompatible key")
-)
-
 // KeyPair provides the central interface to nkeys.
 type KeyPair interface {
 	Seed() ([]byte, error)