chore: add aria2 rpc package

pkg/aria2/rpc/json2.go

@@ -0,0 +1,116 @@
+package rpc
+
+// based on "github.com/gorilla/rpc/v2/json2"
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Copyright 2012 The Gorilla Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"io"
+)
+
+// ----------------------------------------------------------------------------
+// Request and Response
+// ----------------------------------------------------------------------------
+
+// clientRequest represents a JSON-RPC request sent by a client.
+type clientRequest struct {
+	// JSON-RPC protocol.
+	Version string `json:"jsonrpc"`
+
+	// A String containing the name of the method to be invoked.
+	Method string `json:"method"`
+
+	// Object to pass as request parameter to the method.
+	Params interface{} `json:"params"`
+
+	// The request id. This can be of any type. It is used to match the
+	// response with the request that it is replying to.
+	Id uint64 `json:"id"`
+}
+
+// clientResponse represents a JSON-RPC response returned to a client.
+type clientResponse struct {
+	Version string           `json:"jsonrpc"`
+	Result  *json.RawMessage `json:"result"`
+	Error   *json.RawMessage `json:"error"`
+	Id      *uint64          `json:"id"`
+}
+
+// EncodeClientRequest encodes parameters for a JSON-RPC client request.
+func EncodeClientRequest(method string, args interface{}) (*bytes.Buffer, error) {
+	var buf bytes.Buffer
+	c := &clientRequest{
+		Version: "2.0",
+		Method:  method,
+		Params:  args,
+		Id:      reqid(),
+	}
+	if err := json.NewEncoder(&buf).Encode(c); err != nil {
+		return nil, err
+	}
+	return &buf, nil
+}
+
+func (c clientResponse) decode(reply interface{}) error {
+	if c.Error != nil {
+		jsonErr := &Error{}
+		if err := json.Unmarshal(*c.Error, jsonErr); err != nil {
+			return &Error{
+				Code:    E_SERVER,
+				Message: string(*c.Error),
+			}
+		}
+		return jsonErr
+	}
+
+	if c.Result == nil {
+		return ErrNullResult
+	}
+
+	return json.Unmarshal(*c.Result, reply)
+}
+
+// DecodeClientResponse decodes the response body of a client request into
+// the interface reply.
+func DecodeClientResponse(r io.Reader, reply interface{}) error {
+	var c clientResponse
+	if err := json.NewDecoder(r).Decode(&c); err != nil {
+		return err
+	}
+	return c.decode(reply)
+}
+
+type ErrorCode int
+
+const (
+	E_PARSE       ErrorCode = -32700
+	E_INVALID_REQ ErrorCode = -32600
+	E_NO_METHOD   ErrorCode = -32601
+	E_BAD_PARAMS  ErrorCode = -32602
+	E_INTERNAL    ErrorCode = -32603
+	E_SERVER      ErrorCode = -32000
+)
+
+var ErrNullResult = errors.New("result is null")
+
+type Error struct {
+	// A Number that indicates the error type that occurred.
+	Code ErrorCode `json:"code"` /* required */
+
+	// A String providing a short description of the error.
+	// The message SHOULD be limited to a concise single sentence.
+	Message string `json:"message"` /* required */
+
+	// A Primitive or Structured value that contains additional information about the error.
+	Data interface{} `json:"data"` /* optional */
+}
+
+func (e *Error) Error() string {
+	return e.Message
+}