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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.
- //go:build js && wasm
- package http
- import (
- "errors"
- "fmt"
- "io"
- "strconv"
- "syscall/js"
- )
- var uint8Array = js.Global().Get("Uint8Array")
- // jsFetchMode is a Request.Header map key that, if present,
- // signals that the map entry is actually an option to the Fetch API mode setting.
- // Valid values are: "cors", "no-cors", "same-origin", "navigate"
- // The default is "same-origin".
- //
- // Reference: https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters
- const jsFetchMode = "js.fetch:mode"
- // jsFetchCreds is a Request.Header map key that, if present,
- // signals that the map entry is actually an option to the Fetch API credentials setting.
- // Valid values are: "omit", "same-origin", "include"
- // The default is "same-origin".
- //
- // Reference: https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters
- const jsFetchCreds = "js.fetch:credentials"
- // jsFetchRedirect is a Request.Header map key that, if present,
- // signals that the map entry is actually an option to the Fetch API redirect setting.
- // Valid values are: "follow", "error", "manual"
- // The default is "follow".
- //
- // Reference: https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters
- const jsFetchRedirect = "js.fetch:redirect"
- // jsFetchMissing will be true if the Fetch API is not present in
- // the browser globals.
- var jsFetchMissing = js.Global().Get("fetch").IsUndefined()
- // RoundTrip implements the RoundTripper interface using the WHATWG Fetch API.
- func (t *Transport) RoundTrip(req *Request) (*Response, error) {
- // The Transport has a documented contract that states that if the DialContext or
- // DialTLSContext functions are set, they will be used to set up the connections.
- // If they aren't set then the documented contract is to use Dial or DialTLS, even
- // though they are deprecated. Therefore, if any of these are set, we should obey
- // the contract and dial using the regular round-trip instead. Otherwise, we'll try
- // to fall back on the Fetch API, unless it's not available.
- if t.Dial != nil || t.DialContext != nil || t.DialTLS != nil || t.DialTLSContext != nil || jsFetchMissing {
- return t.roundTrip(req)
- }
- ac := js.Global().Get("AbortController")
- if !ac.IsUndefined() {
- // Some browsers that support WASM don't necessarily support
- // the AbortController. See
- // https://developer.mozilla.org/en-US/docs/Web/API/AbortController#Browser_compatibility.
- ac = ac.New()
- }
- opt := js.Global().Get("Object").New()
- // See https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch
- // for options available.
- opt.Set("method", req.Method)
- opt.Set("credentials", "same-origin")
- if h := req.Header.Get(jsFetchCreds); h != "" {
- opt.Set("credentials", h)
- req.Header.Del(jsFetchCreds)
- }
- if h := req.Header.Get(jsFetchMode); h != "" {
- opt.Set("mode", h)
- req.Header.Del(jsFetchMode)
- }
- if h := req.Header.Get(jsFetchRedirect); h != "" {
- opt.Set("redirect", h)
- req.Header.Del(jsFetchRedirect)
- }
- if !ac.IsUndefined() {
- opt.Set("signal", ac.Get("signal"))
- }
- headers := js.Global().Get("Headers").New()
- for key, values := range req.Header {
- for _, value := range values {
- headers.Call("append", key, value)
- }
- }
- opt.Set("headers", headers)
- if req.Body != nil {
- // TODO(johanbrandhorst): Stream request body when possible.
- // See https://bugs.chromium.org/p/chromium/issues/detail?id=688906 for Blink issue.
- // See https://bugzilla.mozilla.org/show_bug.cgi?id=1387483 for Firefox issue.
- // See https://github.com/web-platform-tests/wpt/issues/7693 for WHATWG tests issue.
- // See https://developer.mozilla.org/en-US/docs/Web/API/Streams_API for more details on the Streams API
- // and browser support.
- body, err := io.ReadAll(req.Body)
- if err != nil {
- req.Body.Close() // RoundTrip must always close the body, including on errors.
- return nil, err
- }
- req.Body.Close()
- if len(body) != 0 {
- buf := uint8Array.New(len(body))
- js.CopyBytesToJS(buf, body)
- opt.Set("body", buf)
- }
- }
- fetchPromise := js.Global().Call("fetch", req.URL.String(), opt)
- var (
- respCh = make(chan *Response, 1)
- errCh = make(chan error, 1)
- success, failure js.Func
- )
- success = js.FuncOf(func(this js.Value, args []js.Value) any {
- success.Release()
- failure.Release()
- result := args[0]
- header := Header{}
- // https://developer.mozilla.org/en-US/docs/Web/API/Headers/entries
- headersIt := result.Get("headers").Call("entries")
- for {
- n := headersIt.Call("next")
- if n.Get("done").Bool() {
- break
- }
- pair := n.Get("value")
- key, value := pair.Index(0).String(), pair.Index(1).String()
- ck := CanonicalHeaderKey(key)
- header[ck] = append(header[ck], value)
- }
- contentLength := int64(0)
- clHeader := header.Get("Content-Length")
- switch {
- case clHeader != "":
- cl, err := strconv.ParseInt(clHeader, 10, 64)
- if err != nil {
- errCh <- fmt.Errorf("net/http: ill-formed Content-Length header: %v", err)
- return nil
- }
- if cl < 0 {
- // Content-Length values less than 0 are invalid.
- // See: https://datatracker.ietf.org/doc/html/rfc2616/#section-14.13
- errCh <- fmt.Errorf("net/http: invalid Content-Length header: %q", clHeader)
- return nil
- }
- contentLength = cl
- default:
- // If the response length is not declared, set it to -1.
- contentLength = -1
- }
- b := result.Get("body")
- var body io.ReadCloser
- // The body is undefined when the browser does not support streaming response bodies (Firefox),
- // and null in certain error cases, i.e. when the request is blocked because of CORS settings.
- if !b.IsUndefined() && !b.IsNull() {
- body = &streamReader{stream: b.Call("getReader")}
- } else {
- // Fall back to using ArrayBuffer
- // https://developer.mozilla.org/en-US/docs/Web/API/Body/arrayBuffer
- body = &arrayReader{arrayPromise: result.Call("arrayBuffer")}
- }
- code := result.Get("status").Int()
- respCh <- &Response{
- Status: fmt.Sprintf("%d %s", code, StatusText(code)),
- StatusCode: code,
- Header: header,
- ContentLength: contentLength,
- Body: body,
- Request: req,
- }
- return nil
- })
- failure = js.FuncOf(func(this js.Value, args []js.Value) any {
- success.Release()
- failure.Release()
- errCh <- fmt.Errorf("net/http: fetch() failed: %s", args[0].Get("message").String())
- return nil
- })
- fetchPromise.Call("then", success, failure)
- select {
- case <-req.Context().Done():
- if !ac.IsUndefined() {
- // Abort the Fetch request.
- ac.Call("abort")
- }
- return nil, req.Context().Err()
- case resp := <-respCh:
- return resp, nil
- case err := <-errCh:
- return nil, err
- }
- }
- var errClosed = errors.New("net/http: reader is closed")
- // streamReader implements an io.ReadCloser wrapper for ReadableStream.
- // See https://fetch.spec.whatwg.org/#readablestream for more information.
- type streamReader struct {
- pending []byte
- stream js.Value
- err error // sticky read error
- }
- func (r *streamReader) Read(p []byte) (n int, err error) {
- if r.err != nil {
- return 0, r.err
- }
- if len(r.pending) == 0 {
- var (
- bCh = make(chan []byte, 1)
- errCh = make(chan error, 1)
- )
- success := js.FuncOf(func(this js.Value, args []js.Value) any {
- result := args[0]
- if result.Get("done").Bool() {
- errCh <- io.EOF
- return nil
- }
- value := make([]byte, result.Get("value").Get("byteLength").Int())
- js.CopyBytesToGo(value, result.Get("value"))
- bCh <- value
- return nil
- })
- defer success.Release()
- failure := js.FuncOf(func(this js.Value, args []js.Value) any {
- // Assumes it's a TypeError. See
- // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError
- // for more information on this type. See
- // https://streams.spec.whatwg.org/#byob-reader-read for the spec on
- // the read method.
- errCh <- errors.New(args[0].Get("message").String())
- return nil
- })
- defer failure.Release()
- r.stream.Call("read").Call("then", success, failure)
- select {
- case b := <-bCh:
- r.pending = b
- case err := <-errCh:
- r.err = err
- return 0, err
- }
- }
- n = copy(p, r.pending)
- r.pending = r.pending[n:]
- return n, nil
- }
- func (r *streamReader) Close() error {
- // This ignores any error returned from cancel method. So far, I did not encounter any concrete
- // situation where reporting the error is meaningful. Most users ignore error from resp.Body.Close().
- // If there's a need to report error here, it can be implemented and tested when that need comes up.
- r.stream.Call("cancel")
- if r.err == nil {
- r.err = errClosed
- }
- return nil
- }
- // arrayReader implements an io.ReadCloser wrapper for ArrayBuffer.
- // https://developer.mozilla.org/en-US/docs/Web/API/Body/arrayBuffer.
- type arrayReader struct {
- arrayPromise js.Value
- pending []byte
- read bool
- err error // sticky read error
- }
- func (r *arrayReader) Read(p []byte) (n int, err error) {
- if r.err != nil {
- return 0, r.err
- }
- if !r.read {
- r.read = true
- var (
- bCh = make(chan []byte, 1)
- errCh = make(chan error, 1)
- )
- success := js.FuncOf(func(this js.Value, args []js.Value) any {
- // Wrap the input ArrayBuffer with a Uint8Array
- uint8arrayWrapper := uint8Array.New(args[0])
- value := make([]byte, uint8arrayWrapper.Get("byteLength").Int())
- js.CopyBytesToGo(value, uint8arrayWrapper)
- bCh <- value
- return nil
- })
- defer success.Release()
- failure := js.FuncOf(func(this js.Value, args []js.Value) any {
- // Assumes it's a TypeError. See
- // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError
- // for more information on this type.
- // See https://fetch.spec.whatwg.org/#concept-body-consume-body for reasons this might error.
- errCh <- errors.New(args[0].Get("message").String())
- return nil
- })
- defer failure.Release()
- r.arrayPromise.Call("then", success, failure)
- select {
- case b := <-bCh:
- r.pending = b
- case err := <-errCh:
- return 0, err
- }
- }
- if len(r.pending) == 0 {
- return 0, io.EOF
- }
- n = copy(p, r.pending)
- r.pending = r.pending[n:]
- return n, nil
- }
- func (r *arrayReader) Close() error {
- if r.err == nil {
- r.err = errClosed
- }
- return nil
- }
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