Wrapping errors, some improvements

parser.go

@@ -52,7 +52,7 @@ func (p *Parser) GetPayload() (*PayloadSection, error) {
 	// Validate the payload if automatic validation is enabled
 	if p.opts.withAutomaticValidation {
 		if err := p.payload.Validate(); err != nil {
-			return nil, err
+			return nil, errors.Wrap(err, "payload validation failed")
 		}
 	}
 
@@ -102,17 +102,17 @@ func parseOcmfMessageFromString(data string) (*PayloadSection, *Signature, error
 		return nil, nil, ErrInvalidFormat
 	}
 
-	payloadSection := &PayloadSection{}
-	err := json.Unmarshal([]byte(splitData[0]), payloadSection)
+	payloadSection := PayloadSection{}
+	err := json.Unmarshal([]byte(splitData[0]), &payloadSection)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, errors.Wrap(err, "failed to unmarshal payload")
 	}
 
-	signature := &Signature{}
-	err = json.Unmarshal([]byte(splitData[1]), signature)
+	signature := Signature{}
+	err = json.Unmarshal([]byte(splitData[1]), &signature)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, errors.Wrap(err, "failed to unmarshal signature")
 	}
 
-	return payloadSection, signature, nil
+	return &payloadSection, &signature, nil
 }

validation.go

@@ -71,7 +71,7 @@ func currentTypeValidator(fl validator.FieldLevel) bool {
 	return isValidCurrentType(CurrentType(fl.Field().String()))
 }
 
-var iso8601WithMillisRegex = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2},\d{3}[+-]\d{4}$`)
+var iso8601WithMillisRegex = regexp.MustCompile(`^(?:19|20)\d{2}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])T(?:[01]\d|2[0-3]):[0-5]\d:[0-5]\d(?:Z|-0[1-9]|-1\d|-2[0-3]|-00:?(?:0[1-9]|[1-5]\d)|\+[01]\d|\+2[0-3])(?:|:?[0-5]\d)$`)
 
 func iso8601WithMillisValidator(fl validator.FieldLevel) bool {
 	return iso8601WithMillisRegex.MatchString(fl.Field().String())