status-go/vendor/nhooyr.io/websocket/dial.go

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// +build !js
package websocket
import (
"bufio"
"bytes"
"context"
"crypto/rand"
"encoding/base64"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"strings"
"sync"
"time"
"nhooyr.io/websocket/internal/errd"
)
// DialOptions represents Dial's options.
type DialOptions struct {
// HTTPClient is used for the connection.
// Its Transport must return writable bodies for WebSocket handshakes.
// http.Transport does beginning with Go 1.12.
HTTPClient *http.Client
// HTTPHeader specifies the HTTP headers included in the handshake request.
HTTPHeader http.Header
// Subprotocols lists the WebSocket subprotocols to negotiate with the server.
Subprotocols []string
// CompressionMode controls the compression mode.
// Defaults to CompressionNoContextTakeover.
//
// See docs on CompressionMode for details.
CompressionMode CompressionMode
// CompressionThreshold controls the minimum size of a message before compression is applied.
//
// Defaults to 512 bytes for CompressionNoContextTakeover and 128 bytes
// for CompressionContextTakeover.
CompressionThreshold int
}
// Dial performs a WebSocket handshake on url.
//
// The response is the WebSocket handshake response from the server.
// You never need to close resp.Body yourself.
//
// If an error occurs, the returned response may be non nil.
// However, you can only read the first 1024 bytes of the body.
//
// This function requires at least Go 1.12 as it uses a new feature
// in net/http to perform WebSocket handshakes.
// See docs on the HTTPClient option and https://github.com/golang/go/issues/26937#issuecomment-415855861
//
// URLs with http/https schemes will work and are interpreted as ws/wss.
func Dial(ctx context.Context, u string, opts *DialOptions) (*Conn, *http.Response, error) {
return dial(ctx, u, opts, nil)
}
func dial(ctx context.Context, urls string, opts *DialOptions, rand io.Reader) (_ *Conn, _ *http.Response, err error) {
defer errd.Wrap(&err, "failed to WebSocket dial")
if opts == nil {
opts = &DialOptions{}
}
opts = &*opts
if opts.HTTPClient == nil {
opts.HTTPClient = http.DefaultClient
} else if opts.HTTPClient.Timeout > 0 {
var cancel context.CancelFunc
ctx, cancel = context.WithTimeout(ctx, opts.HTTPClient.Timeout)
defer cancel()
newClient := *opts.HTTPClient
newClient.Timeout = 0
opts.HTTPClient = &newClient
}
if opts.HTTPHeader == nil {
opts.HTTPHeader = http.Header{}
}
secWebSocketKey, err := secWebSocketKey(rand)
if err != nil {
return nil, nil, fmt.Errorf("failed to generate Sec-WebSocket-Key: %w", err)
}
var copts *compressionOptions
if opts.CompressionMode != CompressionDisabled {
copts = opts.CompressionMode.opts()
}
resp, err := handshakeRequest(ctx, urls, opts, copts, secWebSocketKey)
if err != nil {
return nil, resp, err
}
respBody := resp.Body
resp.Body = nil
defer func() {
if err != nil {
// We read a bit of the body for easier debugging.
r := io.LimitReader(respBody, 1024)
timer := time.AfterFunc(time.Second*3, func() {
respBody.Close()
})
defer timer.Stop()
b, _ := ioutil.ReadAll(r)
respBody.Close()
resp.Body = ioutil.NopCloser(bytes.NewReader(b))
}
}()
copts, err = verifyServerResponse(opts, copts, secWebSocketKey, resp)
if err != nil {
return nil, resp, err
}
rwc, ok := respBody.(io.ReadWriteCloser)
if !ok {
return nil, resp, fmt.Errorf("response body is not a io.ReadWriteCloser: %T", respBody)
}
return newConn(connConfig{
subprotocol: resp.Header.Get("Sec-WebSocket-Protocol"),
rwc: rwc,
client: true,
copts: copts,
flateThreshold: opts.CompressionThreshold,
br: getBufioReader(rwc),
bw: getBufioWriter(rwc),
}), resp, nil
}
func handshakeRequest(ctx context.Context, urls string, opts *DialOptions, copts *compressionOptions, secWebSocketKey string) (*http.Response, error) {
u, err := url.Parse(urls)
if err != nil {
return nil, fmt.Errorf("failed to parse url: %w", err)
}
switch u.Scheme {
case "ws":
u.Scheme = "http"
case "wss":
u.Scheme = "https"
case "http", "https":
default:
return nil, fmt.Errorf("unexpected url scheme: %q", u.Scheme)
}
req, _ := http.NewRequestWithContext(ctx, "GET", u.String(), nil)
req.Header = opts.HTTPHeader.Clone()
req.Header.Set("Connection", "Upgrade")
req.Header.Set("Upgrade", "websocket")
req.Header.Set("Sec-WebSocket-Version", "13")
req.Header.Set("Sec-WebSocket-Key", secWebSocketKey)
if len(opts.Subprotocols) > 0 {
req.Header.Set("Sec-WebSocket-Protocol", strings.Join(opts.Subprotocols, ","))
}
if copts != nil {
copts.setHeader(req.Header)
}
resp, err := opts.HTTPClient.Do(req)
if err != nil {
return nil, fmt.Errorf("failed to send handshake request: %w", err)
}
return resp, nil
}
func secWebSocketKey(rr io.Reader) (string, error) {
if rr == nil {
rr = rand.Reader
}
b := make([]byte, 16)
_, err := io.ReadFull(rr, b)
if err != nil {
return "", fmt.Errorf("failed to read random data from rand.Reader: %w", err)
}
return base64.StdEncoding.EncodeToString(b), nil
}
func verifyServerResponse(opts *DialOptions, copts *compressionOptions, secWebSocketKey string, resp *http.Response) (*compressionOptions, error) {
if resp.StatusCode != http.StatusSwitchingProtocols {
return nil, fmt.Errorf("expected handshake response status code %v but got %v", http.StatusSwitchingProtocols, resp.StatusCode)
}
if !headerContainsTokenIgnoreCase(resp.Header, "Connection", "Upgrade") {
return nil, fmt.Errorf("WebSocket protocol violation: Connection header %q does not contain Upgrade", resp.Header.Get("Connection"))
}
if !headerContainsTokenIgnoreCase(resp.Header, "Upgrade", "WebSocket") {
return nil, fmt.Errorf("WebSocket protocol violation: Upgrade header %q does not contain websocket", resp.Header.Get("Upgrade"))
}
if resp.Header.Get("Sec-WebSocket-Accept") != secWebSocketAccept(secWebSocketKey) {
return nil, fmt.Errorf("WebSocket protocol violation: invalid Sec-WebSocket-Accept %q, key %q",
resp.Header.Get("Sec-WebSocket-Accept"),
secWebSocketKey,
)
}
err := verifySubprotocol(opts.Subprotocols, resp)
if err != nil {
return nil, err
}
return verifyServerExtensions(copts, resp.Header)
}
func verifySubprotocol(subprotos []string, resp *http.Response) error {
proto := resp.Header.Get("Sec-WebSocket-Protocol")
if proto == "" {
return nil
}
for _, sp2 := range subprotos {
if strings.EqualFold(sp2, proto) {
return nil
}
}
return fmt.Errorf("WebSocket protocol violation: unexpected Sec-WebSocket-Protocol from server: %q", proto)
}
func verifyServerExtensions(copts *compressionOptions, h http.Header) (*compressionOptions, error) {
exts := websocketExtensions(h)
if len(exts) == 0 {
return nil, nil
}
ext := exts[0]
if ext.name != "permessage-deflate" || len(exts) > 1 || copts == nil {
return nil, fmt.Errorf("WebSocket protcol violation: unsupported extensions from server: %+v", exts[1:])
}
copts = &*copts
for _, p := range ext.params {
switch p {
case "client_no_context_takeover":
copts.clientNoContextTakeover = true
continue
case "server_no_context_takeover":
copts.serverNoContextTakeover = true
continue
}
return nil, fmt.Errorf("unsupported permessage-deflate parameter: %q", p)
}
return copts, nil
}
var bufioReaderPool sync.Pool
func getBufioReader(r io.Reader) *bufio.Reader {
br, ok := bufioReaderPool.Get().(*bufio.Reader)
if !ok {
return bufio.NewReader(r)
}
br.Reset(r)
return br
}
func putBufioReader(br *bufio.Reader) {
bufioReaderPool.Put(br)
}
var bufioWriterPool sync.Pool
func getBufioWriter(w io.Writer) *bufio.Writer {
bw, ok := bufioWriterPool.Get().(*bufio.Writer)
if !ok {
return bufio.NewWriter(w)
}
bw.Reset(w)
return bw
}
func putBufioWriter(bw *bufio.Writer) {
bufioWriterPool.Put(bw)
}