135 lines
3.2 KiB
Go
135 lines
3.2 KiB
Go
// 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
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import (
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"encoding/json"
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"errors"
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"io"
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"net/rpc"
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"sync"
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)
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var errMissingParams = errors.New("jsonrpc: request body missing params")
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type serverCodec 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 serverRequest
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// JSON-RPC clients can use arbitrary json values as request IDs.
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// Package rpc expects uint64 request IDs.
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// We assign uint64 sequence numbers to incoming requests
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// but save the original request ID in the pending map.
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// When rpc responds, we use the sequence number in
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// the response to find the original request ID.
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mutex sync.Mutex // protects seq, pending
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seq uint64
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pending map[uint64]*json.RawMessage
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}
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// NewServerCodec returns a new rpc.ServerCodec using JSON-RPC on conn.
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func NewServerCodec(conn io.ReadWriteCloser) rpc.ServerCodec {
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return &serverCodec{
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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]*json.RawMessage),
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}
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}
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type serverRequest struct {
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Method string `json:"method"`
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Params *json.RawMessage `json:"params"`
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Id *json.RawMessage `json:"id"`
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}
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func (r *serverRequest) reset() {
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r.Method = ""
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r.Params = nil
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r.Id = nil
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}
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type serverResponse struct {
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Id *json.RawMessage `json:"id"`
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Result interface{} `json:"result"`
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Error interface{} `json:"error"`
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}
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func (c *serverCodec) ReadRequestHeader(r *rpc.Request) error {
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c.req.reset()
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if err := c.dec.Decode(&c.req); err != nil {
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return err
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}
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r.ServiceMethod = c.req.Method
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// JSON request id can be any JSON value;
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// RPC package expects uint64. Translate to
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// internal uint64 and save JSON on the side.
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c.mutex.Lock()
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c.seq++
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c.pending[c.seq] = c.req.Id
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c.req.Id = nil
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r.Seq = c.seq
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c.mutex.Unlock()
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return nil
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}
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func (c *serverCodec) ReadRequestBody(x interface{}) error {
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if x == nil {
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return nil
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}
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if c.req.Params == nil {
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return errMissingParams
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}
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// JSON params is array value.
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// RPC params is struct.
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// Unmarshal into array containing struct for now.
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// Should think about making RPC more general.
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var params [1]interface{}
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params[0] = x
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return json.Unmarshal(*c.req.Params, ¶ms)
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}
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var null = json.RawMessage([]byte("null"))
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func (c *serverCodec) WriteResponse(r *rpc.Response, x interface{}) error {
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c.mutex.Lock()
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b, ok := c.pending[r.Seq]
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if !ok {
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c.mutex.Unlock()
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return errors.New("invalid sequence number in response")
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}
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delete(c.pending, r.Seq)
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c.mutex.Unlock()
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if b == nil {
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// Invalid request so no id. Use JSON null.
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b = &null
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}
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resp := serverResponse{Id: b}
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if r.Error == "" {
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resp.Result = x
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} else {
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resp.Error = r.Error
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}
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return c.enc.Encode(resp)
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}
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func (c *serverCodec) Close() error {
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return c.c.Close()
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}
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// ServeConn runs the JSON-RPC server on a single connection.
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// ServeConn blocks, serving the connection until the client hangs up.
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// The caller typically invokes ServeConn in a go statement.
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func ServeConn(conn io.ReadWriteCloser) {
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rpc.ServeCodec(NewServerCodec(conn))
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}
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