Improve coverage of web-handlers.go (#3157)

This patch additionally relaxes the requirement for
accesskeys to be in a regexy set of values.

Fixes #3063

cmd/signature-jwt.go

@@ -44,28 +44,30 @@ const (
 // newJWT - returns new JWT object.
 func newJWT(expiry time.Duration) (*JWT, error) {
 	if serverConfig == nil {
-		return nil, errors.New("Server not initialized")
+		return nil, errServerNotInitialized
 	}
 
 	// Save access, secret keys.
 	cred := serverConfig.GetCredential()
-	if !isValidAccessKey.MatchString(cred.AccessKeyID) {
-		return nil, errors.New("Invalid access key")
+	if !isValidAccessKey(cred.AccessKeyID) {
+		return nil, errInvalidAccessKeyLength
 	}
-	if !isValidSecretKey.MatchString(cred.SecretAccessKey) {
-		return nil, errors.New("Invalid secret key")
+	if !isValidSecretKey(cred.SecretAccessKey) {
+		return nil, errInvalidSecretKeyLength
 	}
-
 	return &JWT{cred, expiry}, nil
 }
 
+var errInvalidAccessKeyLength = errors.New("Invalid access key, access key should be 5 to 20 characters in length.")
+var errInvalidSecretKeyLength = errors.New("Invalid secret key, secret key should be 8 to 40 characters in length.")
+
 // GenerateToken - generates a new Json Web Token based on the incoming access key.
 func (jwt *JWT) GenerateToken(accessKey string) (string, error) {
 	// Trim spaces.
 	accessKey = strings.TrimSpace(accessKey)
 
-	if !isValidAccessKey.MatchString(accessKey) {
-		return "", errors.New("Invalid access key")
+	if !isValidAccessKey(accessKey) {
+		return "", errInvalidAccessKeyLength
 	}
 
 	tUTCNow := time.Now().UTC()
@@ -79,7 +81,6 @@ func (jwt *JWT) GenerateToken(accessKey string) (string, error) {
 }
 
 var errInvalidAccessKeyID = errors.New("The access key ID you provided does not exist in our records.")
-
 var errAuthentication = errors.New("Authentication failed, check your access credentials.")
 
 // Authenticate - authenticates incoming access key and secret key.
@@ -87,11 +88,11 @@ func (jwt *JWT) Authenticate(accessKey, secretKey string) error {
 	// Trim spaces.
 	accessKey = strings.TrimSpace(accessKey)
 
-	if !isValidAccessKey.MatchString(accessKey) {
-		return errors.New("Invalid access key")
+	if !isValidAccessKey(accessKey) {
+		return errInvalidAccessKeyLength
 	}
-	if !isValidSecretKey.MatchString(secretKey) {
-		return errors.New("Invalid secret key")
+	if !isValidSecretKey(secretKey) {
+		return errInvalidSecretKeyLength
 	}
 
 	if accessKey != jwt.AccessKeyID {