You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
75 lines
2.1 KiB
75 lines
2.1 KiB
package protocol
|
|
|
|
import (
|
|
"crypto/rand"
|
|
"fmt"
|
|
"reflect"
|
|
)
|
|
|
|
// RandReader is the random reader the protocol package will use to read
|
|
// random bytes from. This is exported for testing, and should not be used.
|
|
var RandReader = rand.Reader
|
|
|
|
const idempotencyTokenFillTag = `idempotencyToken`
|
|
|
|
// CanSetIdempotencyToken returns true if the struct field should be
|
|
// automatically populated with a Idempotency token.
|
|
//
|
|
// Only *string and string type fields that are tagged with idempotencyToken
|
|
// which are not already set can be auto filled.
|
|
func CanSetIdempotencyToken(v reflect.Value, f reflect.StructField) bool {
|
|
switch u := v.Interface().(type) {
|
|
// To auto fill an Idempotency token the field must be a string,
|
|
// tagged for auto fill, and have a zero value.
|
|
case *string:
|
|
return u == nil && len(f.Tag.Get(idempotencyTokenFillTag)) != 0
|
|
case string:
|
|
return len(u) == 0 && len(f.Tag.Get(idempotencyTokenFillTag)) != 0
|
|
}
|
|
|
|
return false
|
|
}
|
|
|
|
// GetIdempotencyToken returns a randomly generated idempotency token.
|
|
func GetIdempotencyToken() string {
|
|
b := make([]byte, 16)
|
|
RandReader.Read(b)
|
|
|
|
return UUIDVersion4(b)
|
|
}
|
|
|
|
// SetIdempotencyToken will set the value provided with a Idempotency Token.
|
|
// Given that the value can be set. Will panic if value is not setable.
|
|
func SetIdempotencyToken(v reflect.Value) {
|
|
if v.Kind() == reflect.Ptr {
|
|
if v.IsNil() && v.CanSet() {
|
|
v.Set(reflect.New(v.Type().Elem()))
|
|
}
|
|
v = v.Elem()
|
|
}
|
|
v = reflect.Indirect(v)
|
|
|
|
if !v.CanSet() {
|
|
panic(fmt.Sprintf("unable to set idempotnecy token %v", v))
|
|
}
|
|
|
|
b := make([]byte, 16)
|
|
_, err := rand.Read(b)
|
|
if err != nil {
|
|
// TODO handle error
|
|
return
|
|
}
|
|
|
|
v.Set(reflect.ValueOf(UUIDVersion4(b)))
|
|
}
|
|
|
|
// UUIDVersion4 returns a Version 4 random UUID from the byte slice provided
|
|
func UUIDVersion4(u []byte) string {
|
|
// https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_.28random.29
|
|
// 13th character is "4"
|
|
u[6] = (u[6] | 0x40) & 0x4F
|
|
// 17th character is "8", "9", "a", or "b"
|
|
u[8] = (u[8] | 0x80) & 0xBF
|
|
|
|
return fmt.Sprintf(`%X-%X-%X-%X-%X`, u[0:4], u[4:6], u[6:8], u[8:10], u[10:])
|
|
}
|
|
|