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// Copyright 2018 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 jsonrpc2
import (
"bufio"
"context"
"encoding/json"
"fmt"
"io"
"strconv"
"strings"
)
// Reader abstracts the transport mechanics from the JSON RPC protocol.
// A Conn reads messages from the reader it was provided on construction,
// and assumes that each call to Read fully transfers a single message,
// or returns an error.
// A reader is not safe for concurrent use, it is expected it will be used by
// a single Conn in a safe manner.
type Reader interface {
// Read gets the next message from the stream.
Read(context.Context) (Message, int64, error)
}
// Writer abstracts the transport mechanics from the JSON RPC protocol.
// A Conn writes messages using the writer it was provided on construction,
// and assumes that each call to Write fully transfers a single message,
// or returns an error.
// A writer is not safe for concurrent use, it is expected it will be used by
// a single Conn in a safe manner.
type Writer interface {
// Write sends a message to the stream.
Write(context.Context, Message) (int64, error)
}
// Framer wraps low level byte readers and writers into jsonrpc2 message
// readers and writers.
// It is responsible for the framing and encoding of messages into wire form.
type Framer interface {
// Reader wraps a byte reader into a message reader.
Reader(rw io.Reader) Reader
// Writer wraps a byte writer into a message writer.
Writer(rw io.Writer) Writer
}
// RawFramer returns a new Framer.
// The messages are sent with no wrapping, and rely on json decode consistency
// to determine message boundaries.
func RawFramer() Framer { return rawFramer{} }
type rawFramer struct{}
type rawReader struct{ in *json.Decoder }
type rawWriter struct{ out io.Writer }
func (rawFramer) Reader(rw io.Reader) Reader {
return &rawReader{in: json.NewDecoder(rw)}
}
func (rawFramer) Writer(rw io.Writer) Writer {
return &rawWriter{out: rw}
}
func (r *rawReader) Read(ctx context.Context) (Message, int64, error) {
select {
case <-ctx.Done():
return nil, 0, ctx.Err()
default:
}
var raw json.RawMessage
if err := r.in.Decode(&raw); err != nil {
return nil, 0, err
}
msg, err := DecodeMessage(raw)
return msg, int64(len(raw)), err
}
func (w *rawWriter) Write(ctx context.Context, msg Message) (int64, error) {
select {
case <-ctx.Done():
return 0, ctx.Err()
default:
}
data, err := EncodeMessage(msg)
if err != nil {
return 0, fmt.Errorf("marshaling message: %v", err)
}
n, err := w.out.Write(data)
return int64(n), err
}
// HeaderFramer returns a new Framer.
// The messages are sent with HTTP content length and MIME type headers.
// This is the format used by LSP and others.
func HeaderFramer() Framer { return headerFramer{} }
type headerFramer struct{}
type headerReader struct{ in *bufio.Reader }
type headerWriter struct{ out io.Writer }
func (headerFramer) Reader(rw io.Reader) Reader {
return &headerReader{in: bufio.NewReader(rw)}
}
func (headerFramer) Writer(rw io.Writer) Writer {
return &headerWriter{out: rw}
}
func (r *headerReader) Read(ctx context.Context) (Message, int64, error) {
select {
case <-ctx.Done():
return nil, 0, ctx.Err()
default:
}
var total, length int64
// read the header, stop on the first empty line
for {
line, err := r.in.ReadString('\n')
total += int64(len(line))
if err != nil {
return nil, total, fmt.Errorf("failed reading header line: %w", err)
}
line = strings.TrimSpace(line)
// check we have a header line
if line == "" {
break
}
colon := strings.IndexRune(line, ':')
if colon < 0 {
return nil, total, fmt.Errorf("invalid header line %q", line)
}
name, value := line[:colon], strings.TrimSpace(line[colon+1:])
switch name {
case "Content-Length":
if length, err = strconv.ParseInt(value, 10, 32); err != nil {
return nil, total, fmt.Errorf("failed parsing Content-Length: %v", value)
}
if length <= 0 {
return nil, total, fmt.Errorf("invalid Content-Length: %v", length)
}
default:
// ignoring unknown headers
}
}
if length == 0 {
return nil, total, fmt.Errorf("missing Content-Length header")
}
data := make([]byte, length)
n, err := io.ReadFull(r.in, data)
total += int64(n)
if err != nil {
return nil, total, err
}
msg, err := DecodeMessage(data)
return msg, total, err
}
func (w *headerWriter) Write(ctx context.Context, msg Message) (int64, error) {
select {
case <-ctx.Done():
return 0, ctx.Err()
default:
}
data, err := EncodeMessage(msg)
if err != nil {
return 0, fmt.Errorf("marshaling message: %v", err)
}
n, err := fmt.Fprintf(w.out, "Content-Length: %v\r\n\r\n", len(data))
total := int64(n)
if err == nil {
n, err = w.out.Write(data)
total += int64(n)
}
return total, err
}