// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package jsonrpc implements a JSON-RPC 1.0 ClientCodec and ServerCodec
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// for the rpc package.
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// For JSON-RPC 2.0 support, see https://godoc.org/?q=json-rpc+2.0
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package jsonrpc
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import (
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"encoding/json"
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"fmt"
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"io"
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"net"
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"net/rpc"
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"sync"
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)
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type clientCodec struct {
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dec *json.Decoder // for reading JSON values
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enc *json.Encoder // for writing JSON values
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c io.Closer
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// temporary work space
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req clientRequest
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resp clientResponse
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// JSON-RPC responses include the request id but not the request method.
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// Package rpc expects both.
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// We save the request method in pending when sending a request
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// and then look it up by request ID when filling out the rpc Response.
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mutex sync.Mutex // protects pending
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pending map[uint64]string // map request id to method name
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}
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// NewClientCodec returns a new rpc.ClientCodec using JSON-RPC on conn.
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func NewClientCodec(conn io.ReadWriteCloser) rpc.ClientCodec {
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return &clientCodec{
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dec: json.NewDecoder(conn),
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enc: json.NewEncoder(conn),
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c: conn,
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pending: make(map[uint64]string),
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}
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}
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type clientRequest struct {
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Method string `json:"method"`
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Params [1]interface{} `json:"params"`
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Id uint64 `json:"id"`
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}
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func (c *clientCodec) WriteRequest(r *rpc.Request, param interface{}) error {
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c.mutex.Lock()
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c.pending[r.Seq] = r.ServiceMethod
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c.mutex.Unlock()
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c.req.Method = r.ServiceMethod
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c.req.Params[0] = param
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c.req.Id = r.Seq
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return c.enc.Encode(&c.req)
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}
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type clientResponse struct {
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Id uint64 `json:"id"`
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Result *json.RawMessage `json:"result"`
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Error interface{} `json:"error"`
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}
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func (r *clientResponse) reset() {
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r.Id = 0
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r.Result = nil
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r.Error = nil
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}
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func (c *clientCodec) ReadResponseHeader(r *rpc.Response) error {
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c.resp.reset()
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if err := c.dec.Decode(&c.resp); err != nil {
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return err
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}
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c.mutex.Lock()
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r.ServiceMethod = c.pending[c.resp.Id]
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delete(c.pending, c.resp.Id)
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c.mutex.Unlock()
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r.Error = ""
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r.Seq = c.resp.Id
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if c.resp.Error != nil || c.resp.Result == nil {
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x, ok := c.resp.Error.(string)
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if !ok {
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return fmt.Errorf("invalid error %v", c.resp.Error)
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}
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if x == "" {
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x = "unspecified error"
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}
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r.Error = x
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}
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return nil
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}
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func (c *clientCodec) ReadResponseBody(x interface{}) error {
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if x == nil {
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return nil
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}
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return json.Unmarshal(*c.resp.Result, x)
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}
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func (c *clientCodec) Close() error {
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return c.c.Close()
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}
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// NewClient returns a new rpc.Client to handle requests to the
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// set of services at the other end of the connection.
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func NewClient(conn io.ReadWriteCloser) *rpc.Client {
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return rpc.NewClientWithCodec(NewClientCodec(conn))
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}
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// Dial connects to a JSON-RPC server at the specified network address.
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func Dial(network, address string) (*rpc.Client, error) {
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conn, err := net.Dial(network, address)
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if err != nil {
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return nil, err
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}
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return NewClient(conn), err
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}
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