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stream.go
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stream.go
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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"
"net"
"strconv"
"strings"
)
// Stream abstracts the transport mechanics from the JSON RPC protocol.
// A Conn reads and writes messages using the stream it was provided on
// construction, and assumes that each call to Read or Write fully transfers
// a single message, or returns an error.
// A stream is not safe for concurrent use, it is expected it will be used by
// a single Conn in a safe manner.
type Stream interface {
// Read gets the next message from the stream.
Read(context.Context) (Message, int64, error)
// Write sends a message to the stream.
Write(context.Context, Message) (int64, error)
// Close closes the connection.
// Any blocked Read or Write operations will be unblocked and return errors.
Close() error
}
// Framer wraps a network connection up into a Stream.
// It is responsible for the framing and encoding of messages into wire form.
// NewRawStream and NewHeaderStream are implementations of a Framer.
type Framer func(conn net.Conn) Stream
// NewRawStream returns a Stream built on top of a net.Conn.
// The messages are sent with no wrapping, and rely on json decode consistency
// to determine message boundaries.
func NewRawStream(conn net.Conn) Stream {
return &rawStream{
conn: conn,
in: json.NewDecoder(conn),
}
}
type rawStream struct {
conn net.Conn
in *json.Decoder
}
func (s *rawStream) Read(ctx context.Context) (Message, int64, error) {
select {
case <-ctx.Done():
return nil, 0, ctx.Err()
default:
}
var raw json.RawMessage
if err := s.in.Decode(&raw); err != nil {
return nil, 0, err
}
msg, err := DecodeMessage(raw)
return msg, int64(len(raw)), err
}
func (s *rawStream) Write(ctx context.Context, msg Message) (int64, error) {
select {
case <-ctx.Done():
return 0, ctx.Err()
default:
}
data, err := json.Marshal(msg)
if err != nil {
return 0, fmt.Errorf("marshaling message: %v", err)
}
n, err := s.conn.Write(data)
return int64(n), err
}
func (s *rawStream) Close() error {
return s.conn.Close()
}
// NewHeaderStream returns a Stream built on top of a net.Conn.
// The messages are sent with HTTP content length and MIME type headers.
// This is the format used by LSP and others.
func NewHeaderStream(conn net.Conn) Stream {
return &headerStream{
conn: conn,
in: bufio.NewReader(conn),
}
}
type headerStream struct {
conn net.Conn
in *bufio.Reader
}
func (s *headerStream) 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 := s.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)
if _, err := io.ReadFull(s.in, data); err != nil {
return nil, total, err
}
total += length
msg, err := DecodeMessage(data)
return msg, total, err
}
func (s *headerStream) Write(ctx context.Context, msg Message) (int64, error) {
select {
case <-ctx.Done():
return 0, ctx.Err()
default:
}
data, err := json.Marshal(msg)
if err != nil {
return 0, fmt.Errorf("marshaling message: %v", err)
}
n, err := fmt.Fprintf(s.conn, "Content-Length: %v\r\n\r\n", len(data))
total := int64(n)
if err == nil {
n, err = s.conn.Write(data)
total += int64(n)
}
return total, err
}
func (s *headerStream) Close() error {
return s.conn.Close()
}