1 files changed, 134 insertions, 0 deletions
diff --git a/src/net/rpc/jsonrpc/server.go b/src/net/rpc/jsonrpc/server.go
new file mode 100644
index 0000000..40e4e6f
--- /dev/null
+++ b/src/net/rpc/jsonrpc/server.go
@@ -0,0 +1,134 @@
+// Copyright 2010 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 jsonrpc
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/rpc"
+	"sync"
+)
+
+var errMissingParams = errors.New("jsonrpc: request body missing params")
+
+type serverCodec struct {
+	dec *json.Decoder // for reading JSON values
+	enc *json.Encoder // for writing JSON values
+	c   io.Closer
+
+	// temporary work space
+	req serverRequest
+
+	// JSON-RPC clients can use arbitrary json values as request IDs.
+	// Package rpc expects uint64 request IDs.
+	// We assign uint64 sequence numbers to incoming requests
+	// but save the original request ID in the pending map.
+	// When rpc responds, we use the sequence number in
+	// the response to find the original request ID.
+	mutex   sync.Mutex // protects seq, pending
+	seq     uint64
+	pending map[uint64]*json.RawMessage
+}
+
+// NewServerCodec returns a new rpc.ServerCodec using JSON-RPC on conn.
+func NewServerCodec(conn io.ReadWriteCloser) rpc.ServerCodec {
+	return &serverCodec{
+		dec:     json.NewDecoder(conn),
+		enc:     json.NewEncoder(conn),
+		c:       conn,
+		pending: make(map[uint64]*json.RawMessage),
+	}
+}
+
+type serverRequest struct {
+	Method string           `json:"method"`
+	Params *json.RawMessage `json:"params"`
+	Id     *json.RawMessage `json:"id"`
+}
+
+func (r *serverRequest) reset() {
+	r.Method = ""
+	r.Params = nil
+	r.Id = nil
+}
+
+type serverResponse struct {
+	Id     *json.RawMessage `json:"id"`
+	Result interface{}      `json:"result"`
+	Error  interface{}      `json:"error"`
+}
+
+func (c *serverCodec) ReadRequestHeader(r *rpc.Request) error {
+	c.req.reset()
+	if err := c.dec.Decode(&c.req); err != nil {
+		return err
+	}
+	r.ServiceMethod = c.req.Method
+
+	// JSON request id can be any JSON value;
+	// RPC package expects uint64.  Translate to
+	// internal uint64 and save JSON on the side.
+	c.mutex.Lock()
+	c.seq++
+	c.pending[c.seq] = c.req.Id
+	c.req.Id = nil
+	r.Seq = c.seq
+	c.mutex.Unlock()
+
+	return nil
+}
+
+func (c *serverCodec) ReadRequestBody(x interface{}) error {
+	if x == nil {
+		return nil
+	}
+	if c.req.Params == nil {
+		return errMissingParams
+	}
+	// JSON params is array value.
+	// RPC params is struct.
+	// Unmarshal into array containing struct for now.
+	// Should think about making RPC more general.
+	var params [1]interface{}
+	params[0] = x
+	return json.Unmarshal(*c.req.Params, &params)
+}
+
+var null = json.RawMessage([]byte("null"))
+
+func (c *serverCodec) WriteResponse(r *rpc.Response, x interface{}) error {
+	c.mutex.Lock()
+	b, ok := c.pending[r.Seq]
+	if !ok {
+		c.mutex.Unlock()
+		return errors.New("invalid sequence number in response")
+	}
+	delete(c.pending, r.Seq)
+	c.mutex.Unlock()
+
+	if b == nil {
+		// Invalid request so no id. Use JSON null.
+		b = &null
+	}
+	resp := serverResponse{Id: b}
+	if r.Error == "" {
+		resp.Result = x
+	} else {
+		resp.Error = r.Error
+	}
+	return c.enc.Encode(resp)
+}
+
+func (c *serverCodec) Close() error {
+	return c.c.Close()
+}
+
+// ServeConn runs the JSON-RPC server on a single connection.
+// ServeConn blocks, serving the connection until the client hangs up.
+// The caller typically invokes ServeConn in a go statement.
+func ServeConn(conn io.ReadWriteCloser) {
+	rpc.ServeCodec(NewServerCodec(conn))
+}