peridot/vendor/alexejk.io/go-xmlrpc/decode.go

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2022-07-07 20:11:50 +00:00
package xmlrpc
import (
"encoding/base64"
"fmt"
"reflect"
"strconv"
"strings"
"time"
)
const (
errFormatInvalidFieldType = "invalid field type: expected '%s', got '%s'"
)
// Decoder implementations provide mechanisms for parsing of XML-RPC responses to native data-types.
type Decoder interface {
DecodeRaw(body []byte, v interface{}) error
Decode(response *Response, v interface{}) error
DecodeFault(response *Response) *Fault
}
// StdDecoder is the default implementation of the Decoder interface.
type StdDecoder struct{}
func (d *StdDecoder) DecodeRaw(body []byte, v interface{}) error {
response, err := NewResponse(body)
if err != nil {
return err
}
if response.Fault != nil {
return d.decodeFault(response.Fault)
}
return d.Decode(response, v)
}
func (d *StdDecoder) Decode(response *Response, v interface{}) error {
// Validate that v has same number of public fields as response params
if err := fieldsMustEqual(v, len(response.Params)); err != nil {
return err
}
vElem := reflect.Indirect(reflect.ValueOf(v))
for i, param := range response.Params {
field := vElem.Field(i)
if err := d.decodeValue(&param.Value, field); err != nil {
return err
}
}
return nil
}
func (d *StdDecoder) DecodeFault(response *Response) *Fault {
if response.Fault == nil {
return nil
}
return d.decodeFault(response.Fault)
}
func (d *StdDecoder) decodeFault(fault *ResponseFault) *Fault {
f := &Fault{}
for _, m := range fault.Value.Struct {
switch m.Name {
case "faultCode":
if m.Value.Int != "" {
f.Code, _ = strconv.Atoi(m.Value.Int)
} else {
f.Code, _ = strconv.Atoi(m.Value.Int4)
}
case "faultString":
f.String = m.Value.String
}
}
return f
}
func (d *StdDecoder) decodeValue(value *ResponseValue, field reflect.Value) error {
field = indirect(field)
var val interface{}
var err error
switch {
case value.Int != "":
val, err = strconv.Atoi(value.Int)
case value.Int4 != "":
val, err = strconv.Atoi(value.Int4)
case value.Double != "":
val, err = strconv.ParseFloat(value.Double, 64)
case value.Boolean != "":
val, err = d.decodeBoolean(value.Boolean)
case value.String != "":
val, err = value.String, nil
case value.Base64 != "":
val, err = d.decodeBase64(value.Base64)
case value.DateTime != "":
val, err = d.decodeDateTime(value.DateTime)
// Array decoding
case len(value.Array) > 0:
if field.Kind() != reflect.Slice {
return fmt.Errorf(errFormatInvalidFieldType, reflect.Slice.String(), field.Kind().String())
}
slice := reflect.MakeSlice(reflect.TypeOf(field.Interface()), len(value.Array), len(value.Array))
for i, v := range value.Array {
item := slice.Index(i)
if err := d.decodeValue(v, item); err != nil {
return fmt.Errorf("failed decoding array item at index %d: %w", i, err)
}
}
val = slice.Interface()
// Struct decoding
case len(value.Struct) != 0:
if field.Kind() != reflect.Struct {
return fmt.Errorf(errFormatInvalidFieldType, reflect.Struct.String(), field.Kind().String())
}
for _, m := range value.Struct {
// Upper-case the name
fName := structMemberToFieldName(m.Name)
f := field.FieldByName(fName)
if !f.IsValid() {
return fmt.Errorf("cannot find field '%s' on struct", fName)
}
if err := d.decodeValue(&m.Value, f); err != nil {
return fmt.Errorf("failed decoding struct member '%s': %w", m.Name, err)
}
}
default:
// NADA
}
if err != nil {
return err
}
if val != nil {
// Assign if directly assignable, or convert to type if convertible
rVal := reflect.ValueOf(val)
if rVal.Type().AssignableTo(field.Type()) {
field.Set(rVal)
} else {
if !rVal.Type().ConvertibleTo(field.Type()) {
return fmt.Errorf("type '%s' cannot be assigned a value of type '%s'", field.Type().String(), rVal.Type().String())
}
field.Set(rVal.Convert(field.Type()))
}
}
return nil
}
func (d *StdDecoder) decodeBoolean(value string) (bool, error) {
switch value {
case "1", "true", "TRUE", "True":
return true, nil
case "0", "false", "FALSE", "False":
return false, nil
}
return false, fmt.Errorf("unrecognized value '%s' for boolean", value)
}
func (d *StdDecoder) decodeBase64(value string) ([]byte, error) {
return base64.StdEncoding.DecodeString(value)
}
func (d *StdDecoder) decodeDateTime(value string) (time.Time, error) {
return time.Parse(time.RFC3339, value)
}
func fieldsMustEqual(v interface{}, expectation int) error {
vElem := reflect.Indirect(reflect.ValueOf(v))
numFields := 0
for i := 0; i < vElem.NumField(); i++ {
if vElem.Field(i).CanInterface() {
numFields++
}
}
if numFields != expectation {
return fmt.Errorf("number of exported fields (%d) on response type doesnt match expectation (%d)", numFields, expectation)
}
return nil
}
func structMemberToFieldName(structName string) string {
b := new(strings.Builder)
capNext := true
for _, v := range structName {
if v >= 'A' && v <= 'Z' {
b.WriteRune(v)
}
if v >= '0' && v <= '9' {
b.WriteRune(v)
}
if v >= 'a' && v <= 'z' {
if capNext {
b.WriteString(strings.ToUpper(string(v)))
} else {
b.WriteRune(v)
}
}
if v == '_' || v == ' ' || v == '-' || v == '.' {
capNext = true
} else {
capNext = false
}
}
return b.String()
}
// indirect walks down v allocating pointers as needed,
// until it gets to a non-pointer.
//
// Adapted from encoding/json indirect() function
// https://golang.org/src/encoding/json/decode.go?#L480
func indirect(v reflect.Value) reflect.Value {
// After the first round-trip, we set v back to the original value to
// preserve the original RW flags contained in reflect.Value.
v0 := v
haveAddr := false
// If v is a named type and is addressable,
// start with its address, so that if the type has pointer methods,
// we find them.
if v.Kind() != reflect.Ptr && v.Type().Name() != "" && v.CanAddr() {
haveAddr = true
v = v.Addr()
}
for {
// Load value from interface, but only if the result will be
// usefully addressable.
if v.Kind() == reflect.Interface && !v.IsNil() {
e := v.Elem()
if e.Kind() == reflect.Ptr && !e.IsNil() {
haveAddr = false
v = e
continue
}
}
if v.Kind() != reflect.Ptr {
break
}
// Prevent infinite loop if v is an interface pointing to its own address:
// var v interface{}
// v = &v
if v.Elem().Kind() == reflect.Interface && v.Elem().Elem() == v {
v = v.Elem()
break
}
if v.IsNil() {
v.Set(reflect.New(v.Type().Elem()))
}
if haveAddr {
v = v0 // restore original value after round-trip Value.Addr().Elem()
haveAddr = false
} else {
v = v.Elem()
}
}
return v
}