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package corehandlers
import (
"fmt"
"reflect"
"strconv"
"strings"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/request"
)
// ValidateParametersHandler is a request handler to validate the input parameters.
// Validating parameters only has meaning if done prior to the request being sent.
var ValidateParametersHandler = request.NamedHandler{Name: "core.ValidateParametersHandler", Fn: func(r *request.Request) {
if r.ParamsFilled() {
v := validator{errors: []string{}}
v.validateAny(reflect.ValueOf(r.Params), "")
if count := len(v.errors); count > 0 {
format := "%d validation errors:\n- %s"
msg := fmt.Sprintf(format, count, strings.Join(v.errors, "\n- "))
r.Error = awserr.New("InvalidParameter", msg, nil)
}
}
}}
// A validator validates values. Collects validations errors which occurs.
type validator struct {
errors []string
}
// There's no validation to be done on the contents of []byte values. Prepare
// to check validateAny arguments against that type so we can quickly skip
// them.
var byteSliceType = reflect.TypeOf([]byte(nil))
// validateAny will validate any struct, slice or map type. All validations
// are also performed recursively for nested types.
func (v *validator) validateAny(value reflect.Value, path string) {
value = reflect.Indirect(value)
if !value.IsValid() {
return
}
switch value.Kind() {
case reflect.Struct:
v.validateStruct(value, path)
case reflect.Slice:
if value.Type() == byteSliceType {
// We don't need to validate the contents of []byte.
return
}
for i := 0; i < value.Len(); i++ {
v.validateAny(value.Index(i), path+fmt.Sprintf("[%d]", i))
}
case reflect.Map:
for _, n := range value.MapKeys() {
v.validateAny(value.MapIndex(n), path+fmt.Sprintf("[%q]", n.String()))
}
}
}
// validateStruct will validate the struct value's fields. If the structure has
// nested types those types will be validated also.
func (v *validator) validateStruct(value reflect.Value, path string) {
prefix := "."
if path == "" {
prefix = ""
}
for i := 0; i < value.Type().NumField(); i++ {
f := value.Type().Field(i)
if strings.ToLower(f.Name[0:1]) == f.Name[0:1] {
continue
}
fvalue := value.FieldByName(f.Name)
err := validateField(f, fvalue, validateFieldRequired, validateFieldMin)
if err != nil {
v.errors = append(v.errors, fmt.Sprintf("%s: %s", err.Error(), path+prefix+f.Name))
continue
}
v.validateAny(fvalue, path+prefix+f.Name)
}
}
type validatorFunc func(f reflect.StructField, fvalue reflect.Value) error
func validateField(f reflect.StructField, fvalue reflect.Value, funcs ...validatorFunc) error {
for _, fn := range funcs {
if err := fn(f, fvalue); err != nil {
return err
}
}
return nil
}
// Validates that a field has a valid value provided for required fields.
func validateFieldRequired(f reflect.StructField, fvalue reflect.Value) error {
if f.Tag.Get("required") == "" {
return nil
}
switch fvalue.Kind() {
case reflect.Ptr, reflect.Slice, reflect.Map:
if fvalue.IsNil() {
return fmt.Errorf("missing required parameter")
}
default:
if !fvalue.IsValid() {
return fmt.Errorf("missing required parameter")
}
}
return nil
}
// Validates that if a value is provided for a field, that value must be at
// least a minimum length.
func validateFieldMin(f reflect.StructField, fvalue reflect.Value) error {
minStr := f.Tag.Get("min")
if minStr == "" {
return nil
}
min, _ := strconv.ParseInt(minStr, 10, 64)
kind := fvalue.Kind()
if kind == reflect.Ptr {
if fvalue.IsNil() {
return nil
}
fvalue = fvalue.Elem()
}
switch fvalue.Kind() {
case reflect.String:
if int64(fvalue.Len()) < min {
return fmt.Errorf("field too short, minimum length %d", min)
}
case reflect.Slice, reflect.Map:
if fvalue.IsNil() {
return nil
}
if int64(fvalue.Len()) < min {
return fmt.Errorf("field too short, minimum length %d", min)
}
// TODO min can also apply to number minimum value.
}
return nil
}
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