1 files changed, 335 insertions, 0 deletions
diff --git a/rpc/json.go b/rpc/json.go
new file mode 100644
index 0000000..75c2210
--- /dev/null
+++ b/rpc/json.go
@@ -0,0 +1,335 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package rpc
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"reflect"
+	"strings"
+	"sync"
+	"time"
+)
+
+const (
+	vsn                      = "2.0"
+	serviceMethodSeparator   = "_"
+	subscribeMethodSuffix    = "_subscribe"
+	unsubscribeMethodSuffix  = "_unsubscribe"
+	notificationMethodSuffix = "_subscription"
+
+	defaultWriteTimeout = 10 * time.Second // used if context has no deadline
+)
+
+var null = json.RawMessage("null")
+
+type subscriptionResult struct {
+	ID     string          `json:"subscription"`
+	Result json.RawMessage `json:"result,omitempty"`
+}
+
+// A value of this type can a JSON-RPC request, notification, successful response or
+// error response. Which one it is depends on the fields.
+type jsonrpcMessage struct {
+	Version string          `json:"jsonrpc,omitempty"`
+	ID      json.RawMessage `json:"id,omitempty"`
+	Method  string          `json:"method,omitempty"`
+	Params  json.RawMessage `json:"params,omitempty"`
+	Error   *jsonError      `json:"error,omitempty"`
+	Result  json.RawMessage `json:"result,omitempty"`
+}
+
+func (msg *jsonrpcMessage) isNotification() bool {
+	return msg.ID == nil && msg.Method != ""
+}
+
+func (msg *jsonrpcMessage) isCall() bool {
+	return msg.hasValidID() && msg.Method != ""
+}
+
+func (msg *jsonrpcMessage) isResponse() bool {
+	return msg.hasValidID() && msg.Method == "" && msg.Params == nil && (msg.Result != nil || msg.Error != nil)
+}
+
+func (msg *jsonrpcMessage) hasValidID() bool {
+	return len(msg.ID) > 0 && msg.ID[0] != '{' && msg.ID[0] != '['
+}
+
+func (msg *jsonrpcMessage) isSubscribe() bool {
+	return strings.HasSuffix(msg.Method, subscribeMethodSuffix)
+}
+
+func (msg *jsonrpcMessage) isUnsubscribe() bool {
+	return strings.HasSuffix(msg.Method, unsubscribeMethodSuffix)
+}
+
+func (msg *jsonrpcMessage) namespace() string {
+	elem := strings.SplitN(msg.Method, serviceMethodSeparator, 2)
+	return elem[0]
+}
+
+func (msg *jsonrpcMessage) String() string {
+	b, _ := json.Marshal(msg)
+	return string(b)
+}
+
+func (msg *jsonrpcMessage) errorResponse(err error) *jsonrpcMessage {
+	resp := errorMessage(err)
+	resp.ID = msg.ID
+	return resp
+}
+
+func (msg *jsonrpcMessage) response(result interface{}) *jsonrpcMessage {
+	enc, err := json.Marshal(result)
+	if err != nil {
+		// TODO: wrap with 'internal server error'
+		return msg.errorResponse(err)
+	}
+	return &jsonrpcMessage{Version: vsn, ID: msg.ID, Result: enc}
+}
+
+func errorMessage(err error) *jsonrpcMessage {
+	msg := &jsonrpcMessage{Version: vsn, ID: null, Error: &jsonError{
+		Code:    defaultErrorCode,
+		Message: err.Error(),
+	}}
+	ec, ok := err.(Error)
+	if ok {
+		msg.Error.Code = ec.ErrorCode()
+	}
+	return msg
+}
+
+type jsonError struct {
+	Code    int         `json:"code"`
+	Message string      `json:"message"`
+	Data    interface{} `json:"data,omitempty"`
+}
+
+func (err *jsonError) Error() string {
+	if err.Message == "" {
+		return fmt.Sprintf("json-rpc error %d", err.Code)
+	}
+	return err.Message
+}
+
+func (err *jsonError) ErrorCode() int {
+	return err.Code
+}
+
+// Conn is a subset of the methods of net.Conn which are sufficient for ServerCodec.
+type Conn interface {
+	io.ReadWriteCloser
+	SetWriteDeadline(time.Time) error
+}
+
+type deadlineCloser interface {
+	io.Closer
+	SetWriteDeadline(time.Time) error
+}
+
+// ConnRemoteAddr wraps the RemoteAddr operation, which returns a description
+// of the peer address of a connection. If a Conn also implements ConnRemoteAddr, this
+// description is used in log messages.
+type ConnRemoteAddr interface {
+	RemoteAddr() string
+}
+
+// connWithRemoteAddr overrides the remote address of a connection.
+type connWithRemoteAddr struct {
+	Conn
+	addr string
+}
+
+func (c connWithRemoteAddr) RemoteAddr() string { return c.addr }
+
+// jsonCodec reads and writes JSON-RPC messages to the underlying connection. It also has
+// support for parsing arguments and serializing (result) objects.
+type jsonCodec struct {
+	remoteAddr string
+	closer     sync.Once                 // close closed channel once
+	closed     chan interface{}          // closed on Close
+	decode     func(v interface{}) error // decoder to allow multiple transports
+	encMu      sync.Mutex                // guards the encoder
+	encode     func(v interface{}) error // encoder to allow multiple transports
+	conn       deadlineCloser
+}
+
+func newCodec(conn deadlineCloser, encode, decode func(v interface{}) error) ServerCodec {
+	codec := &jsonCodec{
+		closed: make(chan interface{}),
+		encode: encode,
+		decode: decode,
+		conn:   conn,
+	}
+	if ra, ok := conn.(ConnRemoteAddr); ok {
+		codec.remoteAddr = ra.RemoteAddr()
+	}
+	return codec
+}
+
+// NewJSONCodec creates a codec that reads from the given connection. If conn implements
+// ConnRemoteAddr, log messages will use it to include the remote address of the
+// connection.
+func NewJSONCodec(conn Conn) ServerCodec {
+	enc := json.NewEncoder(conn)
+	dec := json.NewDecoder(conn)
+	dec.UseNumber()
+	return newCodec(conn, enc.Encode, dec.Decode)
+}
+
+func (c *jsonCodec) RemoteAddr() string {
+	return c.remoteAddr
+}
+
+func (c *jsonCodec) Read() (msg []*jsonrpcMessage, batch bool, err error) {
+	// Decode the next JSON object in the input stream.
+	// This verifies basic syntax, etc.
+	var rawmsg json.RawMessage
+	if err := c.decode(&rawmsg); err != nil {
+		return nil, false, err
+	}
+	msg, batch = parseMessage(rawmsg)
+	return msg, batch, nil
+}
+
+// Write sends a message to client.
+func (c *jsonCodec) Write(ctx context.Context, v interface{}) error {
+	c.encMu.Lock()
+	defer c.encMu.Unlock()
+
+	deadline, ok := ctx.Deadline()
+	if !ok {
+		deadline = time.Now().Add(defaultWriteTimeout)
+	}
+	c.conn.SetWriteDeadline(deadline)
+	return c.encode(v)
+}
+
+// Close the underlying connection
+func (c *jsonCodec) Close() {
+	c.closer.Do(func() {
+		close(c.closed)
+		c.conn.Close()
+	})
+}
+
+// Closed returns a channel which will be closed when Close is called
+func (c *jsonCodec) Closed() <-chan interface{} {
+	return c.closed
+}
+
+// parseMessage parses raw bytes as a (batch of) JSON-RPC message(s). There are no error
+// checks in this function because the raw message has already been syntax-checked when it
+// is called. Any non-JSON-RPC messages in the input return the zero value of
+// jsonrpcMessage.
+func parseMessage(raw json.RawMessage) ([]*jsonrpcMessage, bool) {
+	if !isBatch(raw) {
+		msgs := []*jsonrpcMessage{{}}
+		json.Unmarshal(raw, &msgs[0])
+		return msgs, false
+	}
+	dec := json.NewDecoder(bytes.NewReader(raw))
+	dec.Token() // skip '['
+	var msgs []*jsonrpcMessage
+	for dec.More() {
+		msgs = append(msgs, new(jsonrpcMessage))
+		dec.Decode(&msgs[len(msgs)-1])
+	}
+	return msgs, true
+}
+
+// isBatch returns true when the first non-whitespace characters is '['
+func isBatch(raw json.RawMessage) bool {
+	for _, c := range raw {
+		// skip insignificant whitespace (http://www.ietf.org/rfc/rfc4627.txt)
+		if c == 0x20 || c == 0x09 || c == 0x0a || c == 0x0d {
+			continue
+		}
+		return c == '['
+	}
+	return false
+}
+
+// parsePositionalArguments tries to parse the given args to an array of values with the
+// given types. It returns the parsed values or an error when the args could not be
+// parsed. Missing optional arguments are returned as reflect.Zero values.
+func parsePositionalArguments(rawArgs json.RawMessage, types []reflect.Type) ([]reflect.Value, error) {
+	dec := json.NewDecoder(bytes.NewReader(rawArgs))
+	var args []reflect.Value
+	tok, err := dec.Token()
+	switch {
+	case err == io.EOF || tok == nil && err == nil:
+		// "params" is optional and may be empty. Also allow "params":null even though it's
+		// not in the spec because our own client used to send it.
+	case err != nil:
+		return nil, err
+	case tok == json.Delim('['):
+		// Read argument array.
+		if args, err = parseArgumentArray(dec, types); err != nil {
+			return nil, err
+		}
+	default:
+		return nil, errors.New("non-array args")
+	}
+	// Set any missing args to nil.
+	for i := len(args); i < len(types); i++ {
+		if types[i].Kind() != reflect.Ptr {
+			return nil, fmt.Errorf("missing value for required argument %d", i)
+		}
+		args = append(args, reflect.Zero(types[i]))
+	}
+	return args, nil
+}
+
+func parseArgumentArray(dec *json.Decoder, types []reflect.Type) ([]reflect.Value, error) {
+	args := make([]reflect.Value, 0, len(types))
+	for i := 0; dec.More(); i++ {
+		if i >= len(types) {
+			return args, fmt.Errorf("too many arguments, want at most %d", len(types))
+		}
+		argval := reflect.New(types[i])
+		if err := dec.Decode(argval.Interface()); err != nil {
+			return args, fmt.Errorf("invalid argument %d: %v", i, err)
+		}
+		if argval.IsNil() && types[i].Kind() != reflect.Ptr {
+			return args, fmt.Errorf("missing value for required argument %d", i)
+		}
+		args = append(args, argval.Elem())
+	}
+	// Read end of args array.
+	_, err := dec.Token()
+	return args, err
+}
+
+// parseSubscriptionName extracts the subscription name from an encoded argument array.
+func parseSubscriptionName(rawArgs json.RawMessage) (string, error) {
+	dec := json.NewDecoder(bytes.NewReader(rawArgs))
+	if tok, _ := dec.Token(); tok != json.Delim('[') {
+		return "", errors.New("non-array args")
+	}
+	v, _ := dec.Token()
+	method, ok := v.(string)
+	if !ok {
+		return "", errors.New("expected subscription name as first argument")
+	}
+	return method, nil
+}