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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package jsonrpc2
import (
"encoding/json"
"errors"
"fmt"
)
// Message is the interface to all jsonrpc2 message types.
// They share no common functionality, but are a closed set of concrete types
// that are allowed to implement this interface. The message types are *Call,
// *Notification and *Response.
type Message interface {
// isJSONRPC2Message is used to make the set of message implementations a
// closed set.
isJSONRPC2Message()
}
// Request is the shared interface to jsonrpc2 messages that request
// a method be invoked.
// The request types are a closed set of *Call and *Notification.
type Request interface {
Message
// Method is a string containing the method name to invoke.
Method() string
// Params is an JSON value (object, array, null, or "") with the parameters of the method.
Params() json.RawMessage
// isJSONRPC2Request is used to make the set of request implementations closed.
isJSONRPC2Request()
}
// Notification is a request for which a response cannot occur, and as such
// it has not ID.
type Notification struct {
// Method is a string containing the method name to invoke.
method string
params json.RawMessage
}
// Call is a request that expects a response.
// The response will have a matching ID.
type Call struct {
// Method is a string containing the method name to invoke.
method string
// Params is a JSON value (object, array, null, or "") with the parameters of the method.
params json.RawMessage
// id of this request, used to tie the Response back to the request.
id ID
}
// Response is a reply to a Call.
// It will have the same ID as the call it is a response to.
type Response struct {
// result is the content of the response.
result json.RawMessage
// err is set only if the call failed.
err error
// ID of the request this is a response to.
id ID
}
// NewNotification constructs a new Notification message for the supplied
// method and parameters.
func NewNotification(method string, params interface{}) (*Notification, error) {
p, merr := marshalToRaw(params)
return &Notification{method: method, params: p}, merr
}
func (msg *Notification) Method() string { return msg.method }
func (msg *Notification) Params() json.RawMessage { return msg.params }
func (msg *Notification) isJSONRPC2Message() {}
func (msg *Notification) isJSONRPC2Request() {}
func (n *Notification) MarshalJSON() ([]byte, error) {
msg := wireRequest{Method: n.method, Params: &n.params}
data, err := json.Marshal(msg)
if err != nil {
return data, fmt.Errorf("marshaling notification: %w", err)
}
return data, nil
}
func (n *Notification) UnmarshalJSON(data []byte) error {
msg := wireRequest{}
if err := json.Unmarshal(data, &msg); err != nil {
return fmt.Errorf("unmarshaling notification: %w", err)
}
n.method = msg.Method
if msg.Params != nil {
n.params = *msg.Params
}
return nil
}
// NewCall constructs a new Call message for the supplied ID, method and
// parameters.
func NewCall(id ID, method string, params interface{}) (*Call, error) {
p, merr := marshalToRaw(params)
return &Call{id: id, method: method, params: p}, merr
}
func (msg *Call) Method() string { return msg.method }
func (msg *Call) Params() json.RawMessage { return msg.params }
func (msg *Call) ID() ID { return msg.id }
func (msg *Call) isJSONRPC2Message() {}
func (msg *Call) isJSONRPC2Request() {}
func (c *Call) MarshalJSON() ([]byte, error) {
msg := wireRequest{Method: c.method, Params: &c.params, ID: &c.id}
data, err := json.Marshal(msg)
if err != nil {
return data, fmt.Errorf("marshaling call: %w", err)
}
return data, nil
}
func (c *Call) UnmarshalJSON(data []byte) error {
msg := wireRequest{}
if err := json.Unmarshal(data, &msg); err != nil {
return fmt.Errorf("unmarshaling call: %w", err)
}
c.method = msg.Method
if msg.Params != nil {
c.params = *msg.Params
}
if msg.ID != nil {
c.id = *msg.ID
}
return nil
}
// NewResponse constructs a new Response message that is a reply to the
// supplied. If err is set result may be ignored.
func NewResponse(id ID, result interface{}, err error) (*Response, error) {
r, merr := marshalToRaw(result)
return &Response{id: id, result: r, err: err}, merr
}
func (msg *Response) ID() ID { return msg.id }
func (msg *Response) Result() json.RawMessage { return msg.result }
func (msg *Response) Err() error { return msg.err }
func (msg *Response) isJSONRPC2Message() {}
func (r *Response) MarshalJSON() ([]byte, error) {
msg := &wireResponse{Error: toWireError(r.err), ID: &r.id}
if msg.Error == nil {
msg.Result = &r.result
}
data, err := json.Marshal(msg)
if err != nil {
return data, fmt.Errorf("marshaling notification: %w", err)
}
return data, nil
}
func toWireError(err error) *WireError {
if err == nil {
// no error, the response is complete
return nil
}
if err, ok := err.(*WireError); ok {
// already a wire error, just use it
return err
}
result := &WireError{Message: err.Error()}
var wrapped *WireError
if errors.As(err, &wrapped) {
// if we wrapped a wire error, keep the code from the wrapped error
// but the message from the outer error
result.Code = wrapped.Code
}
return result
}
func (r *Response) UnmarshalJSON(data []byte) error {
msg := wireResponse{}
if err := json.Unmarshal(data, &msg); err != nil {
return fmt.Errorf("unmarshaling jsonrpc response: %w", err)
}
if msg.Result != nil {
r.result = *msg.Result
}
if msg.Error != nil {
r.err = msg.Error
}
if msg.ID != nil {
r.id = *msg.ID
}
return nil
}
func DecodeMessage(data []byte) (Message, error) {
msg := wireCombined{}
if err := json.Unmarshal(data, &msg); err != nil {
return nil, fmt.Errorf("unmarshaling jsonrpc message: %w", err)
}
if msg.Method == "" {
// no method, should be a response
if msg.ID == nil {
return nil, ErrInvalidRequest
}
response := &Response{id: *msg.ID}
if msg.Error != nil {
response.err = msg.Error
}
if msg.Result != nil {
response.result = *msg.Result
}
return response, nil
}
// has a method, must be a request
if msg.ID == nil {
// request with no ID is a notify
notify := &Notification{method: msg.Method}
if msg.Params != nil {
notify.params = *msg.Params
}
return notify, nil
}
// request with an ID, must be a call
call := &Call{method: msg.Method, id: *msg.ID}
if msg.Params != nil {
call.params = *msg.Params
}
return call, nil
}
func marshalToRaw(obj interface{}) (json.RawMessage, error) {
data, err := json.Marshal(obj)
if err != nil {
return json.RawMessage{}, err
}
return json.RawMessage(data), nil
}