/
jsonrpc.go
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/
jsonrpc.go
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// Copyright (c) 2014 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package btcjson
import (
"encoding/json"
"fmt"
)
// RPCErrorCode represents an error code to be used as a part of an RPCError
// which is in turn used in a JSON-RPC Response object.
//
// A specific type is used to help ensure the wrong errors aren't used.
type RPCErrorCode int
// RPCError represents an error that is used as a part of a JSON-RPC Response
// object.
type RPCError struct {
Code RPCErrorCode `json:"code,omitempty"`
Message string `json:"message,omitempty"`
}
// Guarantee RPCError satisifies the builtin error interface.
var _, _ error = RPCError{}, (*RPCError)(nil)
// Error returns a string describing the RPC error. This satisifies the
// builtin error interface.
func (e RPCError) Error() string {
return fmt.Sprintf("%d: %s", e.Code, e.Message)
}
// NewRPCError constructs and returns a new JSON-RPC error that is suitable
// for use in a JSON-RPC Response object.
func NewRPCError(code RPCErrorCode, message string) *RPCError {
return &RPCError{
Code: code,
Message: message,
}
}
// IsValidIDType checks that the ID field (which can go in any of the JSON-RPC
// requests, responses, or notifications) is valid. JSON-RPC 1.0 allows any
// valid JSON type. JSON-RPC 2.0 (which bitcoind follows for some parts) only
// allows string, number, or null, so this function restricts the allowed types
// to that list. This function is only provided in case the caller is manually
// marshalling for some reason. The functions which accept an ID in this
// package already call this function to ensure the provided id is valid.
func IsValidIDType(id interface{}) bool {
switch id.(type) {
case int, int8, int16, int32, int64,
uint, uint8, uint16, uint32, uint64,
float32, float64,
string,
nil:
return true
default:
return false
}
}
// Request represents raw JSON-RPC requests. The Method field identifies the
// specific command type which in turn leads to different parameters. Callers
// typically will not use this directly since this package provides a statically
// typed command infrastructure which handles creation of these requests,
// however this struct is being exported in case the caller wants to construct
// raw requests for some reason.
type Request struct {
Jsonrpc string `json:"jsonrpc"`
Method string `json:"method"`
Params []json.RawMessage `json:"params"`
ID interface{} `json:"id"`
}
// UnmarshalJSON is a custom unmarshal func for the Request struct. The param
// field defaults to an empty json.RawMessage array it is omitted by the request
// or nil if the supplied value is invalid.
func (request *Request) UnmarshalJSON(b []byte) error {
var data map[string]interface{}
err := json.Unmarshal(b, &data)
if err != nil {
return err
}
request.ID = data["id"]
methodValue, hasMethod := data["method"]
if hasMethod {
request.Method = methodValue.(string)
}
jsonrpcValue, hasJsonrpc := data["jsonrpc"]
if hasJsonrpc {
request.Jsonrpc = jsonrpcValue.(string)
}
paramsValue, hasParams := data["params"]
if !hasParams {
// set the request param to an empty array if it is ommited in the request
request.Params = []json.RawMessage{}
}
if hasParams {
// assert the request params is an array of data
params, paramsOk := paramsValue.([]interface{})
if paramsOk {
rawParams := make([]json.RawMessage, 0, len(params))
for _, param := range params {
marshalledParam, err := json.Marshal(param)
if err != nil {
return err
}
rawMessage := json.RawMessage(marshalledParam)
rawParams = append(rawParams, rawMessage)
}
request.Params = rawParams
}
}
return nil
}
// NewRequest returns a new JSON-RPC request object given the provided rpc
// version, id, method, and parameters. The parameters are marshalled into a
// json.RawMessage for the Params field of the returned request object. This
// function is only provided in case the caller wants to construct raw requests
// for some reason. Typically callers will instead want to create a registered
// concrete command type with the NewCmd or New<Foo>Cmd functions and call the
// MarshalCmd function with that command to generate the marshalled JSON-RPC
// request.
func NewRequest(rpcVersion string, id interface{}, method string, params []interface{}) (*Request, error) {
// default to JSON-RPC 1.0 if RPC type is not specified
if rpcVersion != "2.0" && rpcVersion != "1.0" {
rpcVersion = "1.0"
}
if !IsValidIDType(id) {
str := fmt.Sprintf("the id of type '%T' is invalid", id)
return nil, makeError(ErrInvalidType, str)
}
rawParams := make([]json.RawMessage, 0, len(params))
for _, param := range params {
marshalledParam, err := json.Marshal(param)
if err != nil {
return nil, err
}
rawMessage := json.RawMessage(marshalledParam)
rawParams = append(rawParams, rawMessage)
}
return &Request{
Jsonrpc: rpcVersion,
ID: id,
Method: method,
Params: rawParams,
}, nil
}
// Response is the general form of a JSON-RPC response. The type of the
// Result field varies from one command to the next, so it is implemented as an
// interface. The ID field has to be a pointer to allow for a nil value when
// empty.
type Response struct {
Jsonrpc string `json:"jsonrpc"`
Result json.RawMessage `json:"result"`
Error *RPCError `json:"error"`
ID *interface{} `json:"id"`
}
// NewResponse returns a new JSON-RPC response object given the provided rpc
// version, id, marshalled result, and RPC error. This function is only
// provided in case the caller wants to construct raw responses for some reason.
// Typically callers will instead want to create the fully marshalled JSON-RPC
// response to send over the wire with the MarshalResponse function.
func NewResponse(rpcVersion string, id interface{}, marshalledResult []byte, rpcErr *RPCError) (*Response, error) {
if rpcVersion != "2.0" && rpcVersion != "1.0" {
rpcVersion = "1.0"
}
if !IsValidIDType(id) {
str := fmt.Sprintf("the id of type '%T' is invalid", id)
return nil, makeError(ErrInvalidType, str)
}
pid := &id
return &Response{
Jsonrpc: rpcVersion,
Result: marshalledResult,
Error: rpcErr,
ID: pid,
}, nil
}
// MarshalResponse marshals the passed rpc version, id, result, and RPCError to
// a JSON-RPC response byte slice that is suitable for transmission to a
// JSON-RPC client.
func MarshalResponse(rpcVersion string, id interface{}, result interface{}, rpcErr *RPCError) ([]byte, error) {
if rpcVersion != "2.0" && rpcVersion != "1.0" {
rpcVersion = "1.0"
}
marshalledResult, err := json.Marshal(result)
if err != nil {
return nil, err
}
response, err := NewResponse(rpcVersion, id, marshalledResult, rpcErr)
if err != nil {
return nil, err
}
return json.Marshal(&response)
}