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rpcenc: Support reader redirect

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This commit is contained in:
Łukasz Magiera 2021-07-30 12:58:28 +02:00
parent c17a0c4fed
commit 0c809d3a5f
2 changed files with 287 additions and 34 deletions
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262
lib/rpcenc/reader.go
View File

@ -40,7 +40,63 @@ type ReaderStream struct {
Info string
}
var client = func() *http.Client {
c := *http.DefaultClient
c.CheckRedirect = func(req *http.Request, via []*http.Request) error {
return http.ErrUseLastResponse
}
return &c
}()
/*
Example rpc function:
Push(context.Context, io.Reader) error
Request flow:
1. Client invokes a method with an io.Reader param\
2. go-jsonrpc invokes `ReaderParamEncoder` for the client-provided io.Reader
3. `ReaderParamEncoder` transforms the reader into a `ReaderStream` which can
be serialized as JSON, and sent as jsonrpc request parameter
3.1. If the reader is of type `*sealing.NullReader`, the resulting object
is `ReaderStream{ Type: "null", Info: "[base 10 number of bytes]" }`
3.2. If the reader is of type `*rpcReader`, and it wasn't read from, we
notify that rpcReader to go a different push endpoint, and return
a `ReaderStream` object like in 3.4.
3.3. In remaining cases we start a goroutine which:
3.3.1. Makes a HEAD request to the server push endpoint
3.3.2. If the HEAD request is redirected, it follows the redirect
3.3.3. If the request succeeds, it starts a POST request to the
endpoint to which the last HEAD request was sent with the
reader set as request body.
3.4. We return a `ReaderStream` indicating the uuid of push request, ex:
`ReaderStream{ Type: "push", Info: "[UUID string]" }`
4. If the reader wasn't a NullReader, the server will receive a HEAD (or
POST in case of older clients) request to the push endpoint.
4.1. The server gets or registers an `*rpcReader` in the `readers` map.
4.2. It waits for a request to a matching push endpoint to be opened
4.3. After the request is opened, it returns the `*rpcReader` to
go-jsonrpc, which will pass it as the io.Reader parameter to the
rpc method implementation
4.4. If the first request made to the push endpoint was a POST, the
returned `*rpcReader` acts as a simple reader reading the POST
request body
4.5. If the first request made to the push endpoint was a HEAD
4.5.1. On the first call to Read or Close the server responds with
a 200 OK header, the client starts a POST request to the same
push URL, and the reader starts passing through the POST request
body
4.5.2. If the reader is passed to another (now client) RPC method as a
reader parameter, the server for the first request responds to the
HEAD request with http 302 Found, instructing the first client to
go to the push endpoint of the second RPC server
5. If the reader was a NullReader (ReaderStream.Type=="null"), we instantiate
it, and provide to the method implementation
*/
func ReaderParamEncoder(addr string) jsonrpc.Option {
// Client side parameter encoder. Runs on the rpc client side. io.Reader -> ReaderStream{}
return jsonrpc.WithParamEncoder(new(io.Reader), func(value reflect.Value) (reflect.Value, error) {
r := value.Interface().(io.Reader)
@ -55,62 +111,171 @@ func ReaderParamEncoder(addr string) jsonrpc.Option {
}
u.Path = path.Join(u.Path, reqID.String())
go func() {
// TODO: figure out errors here
rpcReader, redir := r.(*rpcReader)
if redir {
// if we have an rpc stream, redirect instead of proxying all the data
redir = rpcReader.redirect(u.String())
}
resp, err := http.Post(u.String(), "application/octet-stream", r)
if err != nil {
log.Errorf("sending reader param: %+v", err)
return
}
if !redir {
go func() {
// TODO: figure out errors here
for {
req, err := http.NewRequest("HEAD", u.String(), nil)
if err != nil {
log.Errorf("sending HEAD request for the reder param: %+v", err)
return
}
req.Header.Set("Content-Type", "application/octet-stream")
resp, err := client.Do(req)
if err != nil {
log.Errorf("sending reader param: %+v", err)
return
}
// todo do we need to close the body for a head request?
defer resp.Body.Close() //nolint:errcheck
if resp.StatusCode == http.StatusFound {
nextStr := resp.Header.Get("Location")
u, err = url.Parse(nextStr)
if err != nil {
log.Errorf("sending HEAD request for the reder param, parsing next url (%s): %+v", nextStr, err)
return
}
if resp.StatusCode != 200 {
b, _ := ioutil.ReadAll(resp.Body)
log.Errorf("sending reader param (%s): non-200 status: %s, msg: '%s'", u.String(), resp.Status, string(b))
return
}
continue
}
}()
if resp.StatusCode == http.StatusNoContent { // reader closed before reading anything
// todo just return??
return
}
if resp.StatusCode != http.StatusOK {
b, _ := ioutil.ReadAll(resp.Body)
log.Errorf("sending reader param (%s): non-200 status: %s, msg: '%s'", u.String(), resp.Status, string(b))
return
}
break
}
// now actually send the data
req, err := http.NewRequest("POST", u.String(), r)
if err != nil {
log.Errorf("sending reader param: %+v", err)
return
}
req.Header.Set("Content-Type", "application/octet-stream")
resp, err := client.Do(req)
if err != nil {
log.Errorf("sending reader param: %+v", err)
return
}
defer resp.Body.Close() //nolint
if resp.StatusCode != http.StatusOK {
b, _ := ioutil.ReadAll(resp.Body)
log.Errorf("sending reader param (%s): non-200 status: %s, msg: '%s'", u.String(), resp.Status, string(b))
return
}
}()
}
return reflect.ValueOf(ReaderStream{Type: PushStream, Info: reqID.String()}), nil
})
}
// watchReadCloser watches the ReadCloser and closes the watch channel when
type resType int
const (
resStart resType = iota // send on first read after HEAD
resRedirect // send on redirect before first read after HEAD
// done/closed = close res channel
)
type readRes struct {
rt resType
meta string
}
// rpcReader watches the ReadCloser and closes the res channel when
// either: (1) the ReaderCloser fails on Read (including with a benign error
// like EOF), or (2) when Close is called.
//
// Use it be notified of terminal states, in situations where a Read failure (or
// EOF) is considered a terminal state too (besides Close).
type watchReadCloser struct {
io.ReadCloser
watch chan struct{}
type rpcReader struct {
postBody io.ReadCloser // nil on initial head request
next chan *rpcReader // on head will get us the postBody after sending resStart
res chan readRes
beginOnce *sync.Once
closeOnce sync.Once
}
func (w *watchReadCloser) Read(p []byte) (int, error) {
n, err := w.ReadCloser.Read(p)
func (w *rpcReader) beginPost() {
if w.postBody == nil {
w.res <- readRes{
rt: resStart,
}
nr := <-w.next
w.postBody = nr.postBody
w.res = nr.res
w.beginOnce = nr.beginOnce
}
}
func (w *rpcReader) Read(p []byte) (int, error) {
w.beginOnce.Do(func() {
w.beginPost()
})
if w.postBody == nil {
return 0, xerrors.Errorf("reader already closed or redirected")
}
n, err := w.postBody.Read(p)
if err != nil {
w.closeOnce.Do(func() {
close(w.watch)
close(w.res)
})
}
return n, err
}
func (w *watchReadCloser) Close() error {
func (w *rpcReader) Close() error {
w.closeOnce.Do(func() {
close(w.watch)
close(w.res)
})
return w.ReadCloser.Close()
return w.postBody.Close()
}
func (w *rpcReader) redirect(to string) bool {
done := false
w.beginOnce.Do(func() {
w.closeOnce.Do(func() {
w.res <- readRes{
rt: resRedirect,
meta: to,
}
done = true
close(w.res)
})
})
return done
}
func ReaderParamDecoder() (http.HandlerFunc, jsonrpc.ServerOption) {
var readersLk sync.Mutex
readers := map[uuid.UUID]chan *watchReadCloser{}
readers := map[uuid.UUID]chan *rpcReader{}
// runs on the rpc server side, called by the client before making the jsonrpc request
hnd := func(resp http.ResponseWriter, req *http.Request) {
strId := path.Base(req.URL.Path)
u, err := uuid.Parse(strId)
@ -122,14 +287,24 @@ func ReaderParamDecoder() (http.HandlerFunc, jsonrpc.ServerOption) {
readersLk.Lock()
ch, found := readers[u]
if !found {
ch = make(chan *watchReadCloser)
ch = make(chan *rpcReader)
readers[u] = ch
}
readersLk.Unlock()
wr := &watchReadCloser{
ReadCloser: req.Body,
watch: make(chan struct{}),
wr := &rpcReader{
res: make(chan readRes),
next: ch,
beginOnce: &sync.Once{},
}
switch req.Method {
case http.MethodHead:
// leave body nil
case http.MethodPost:
wr.postBody = req.Body
default:
http.Error(resp, "unsupported method", http.StatusMethodNotAllowed)
}
tctx, cancel := context.WithTimeout(req.Context(), Timeout)
@ -145,18 +320,37 @@ func ReaderParamDecoder() (http.HandlerFunc, jsonrpc.ServerOption) {
}
select {
case <-wr.watch:
case res, ok := <-wr.res:
if !ok {
if req.Method == http.MethodHead {
resp.WriteHeader(http.StatusNoContent)
} else {
resp.WriteHeader(http.StatusOK)
}
return
}
// TODO should we check if we failed the Read, and if so
// return an HTTP 500? i.e. turn watch into a chan error?
// return an HTTP 500? i.e. turn res into a chan error?
switch res.rt {
case resRedirect:
http.Redirect(resp, req, res.meta, http.StatusFound)
case resStart: // responding to HEAD, request POST with reader data
resp.WriteHeader(http.StatusOK)
default:
log.Errorf("unknown res.rt")
resp.WriteHeader(500)
}
return
case <-req.Context().Done():
log.Errorf("context error in reader stream handler (2): %v", req.Context().Err())
resp.WriteHeader(500)
return
}
resp.WriteHeader(200)
}
// Server side reader decoder. runs on the rpc server side, invoked when decoding client request parameters. json(ReaderStream{}) -> io.Reader
dec := jsonrpc.WithParamDecoder(new(io.Reader), func(ctx context.Context, b []byte) (reflect.Value, error) {
var rs ReaderStream
if err := json.Unmarshal(b, &rs); err != nil {
@ -180,7 +374,7 @@ func ReaderParamDecoder() (http.HandlerFunc, jsonrpc.ServerOption) {
readersLk.Lock()
ch, found := readers[u]
if !found {
ch = make(chan *watchReadCloser)
ch = make(chan *rpcReader)
readers[u] = ch
}
readersLk.Unlock()

59
lib/rpcenc/reader_test.go
View File

@ -16,6 +16,11 @@ import (
)
type ReaderHandler struct {
readApi func(ctx context.Context, r io.Reader) ([]byte, error)
}
func (h *ReaderHandler) ReadAllApi(ctx context.Context, r io.Reader) ([]byte, error) {
return h.readApi(ctx, r)
}
func (h *ReaderHandler) ReadAll(ctx context.Context, r io.Reader) ([]byte, error) {
@ -88,3 +93,57 @@ func TestNullReaderProxy(t *testing.T) {
require.NoError(t, err)
require.Equal(t, int64(1016), n)
}
func TestReaderRedirect(t *testing.T) {
var allClient struct {
ReadAll func(ctx context.Context, r io.Reader) ([]byte, error)
}
{
allServerHandler := &ReaderHandler{}
readerHandler, readerServerOpt := ReaderParamDecoder()
rpcServer := jsonrpc.NewServer(readerServerOpt)
rpcServer.Register("ReaderHandler", allServerHandler)
mux := mux.NewRouter()
mux.Handle("/rpc/v0", rpcServer)
mux.Handle("/rpc/streams/v0/push/{uuid}", readerHandler)
testServ := httptest.NewServer(mux)
defer testServ.Close()
re := ReaderParamEncoder("http://" + testServ.Listener.Addr().String() + "/rpc/streams/v0/push")
closer, err := jsonrpc.NewMergeClient(context.Background(), "ws://"+testServ.Listener.Addr().String()+"/rpc/v0", "ReaderHandler", []interface{}{&allClient}, nil, re)
require.NoError(t, err)
defer closer()
}
var redirClient struct {
ReadAllApi func(ctx context.Context, r io.Reader) ([]byte, error)
}
{
allServerHandler := &ReaderHandler{readApi: allClient.ReadAll}
readerHandler, readerServerOpt := ReaderParamDecoder()
rpcServer := jsonrpc.NewServer(readerServerOpt)
rpcServer.Register("ReaderHandler", allServerHandler)
mux := mux.NewRouter()
mux.Handle("/rpc/v0", rpcServer)
mux.Handle("/rpc/streams/v0/push/{uuid}", readerHandler)
testServ := httptest.NewServer(mux)
defer testServ.Close()
re := ReaderParamEncoder("http://" + testServ.Listener.Addr().String() + "/rpc/streams/v0/push")
closer, err := jsonrpc.NewMergeClient(context.Background(), "ws://"+testServ.Listener.Addr().String()+"/rpc/v0", "ReaderHandler", []interface{}{&redirClient}, nil, re)
require.NoError(t, err)
defer closer()
}
read, err := redirClient.ReadAllApi(context.TODO(), strings.NewReader("rediracted pooooootato"))
require.NoError(t, err)
require.Equal(t, "rediracted pooooootato", string(read), "potatoes weren't equal")
}