From d235e2c6a5788ec4a6cff15a16f56b38a3876a0d Mon Sep 17 00:00:00 2001 From: Determinant Date: Sun, 28 Jun 2020 14:47:41 -0400 Subject: ... --- rpc/json.go | 335 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 335 insertions(+) create mode 100644 rpc/json.go (limited to 'rpc/json.go') 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 . + +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 +} -- cgit v1.2.3