cloudflared-mirror/h2mux/muxedstream.go

358 lines
9.9 KiB
Go

package h2mux
import (
"bytes"
"io"
"sync"
)
type ReadWriteLengther interface {
io.ReadWriter
Reset()
Len() int
}
type ReadWriteClosedCloser interface {
io.ReadWriteCloser
Closed() bool
}
// MuxedStream is logically an HTTP/2 stream, with an additional buffer for outgoing data.
type MuxedStream struct {
streamID uint32
// The "Receive" end of the stream
readBufferLock sync.RWMutex
readBuffer ReadWriteClosedCloser
// This is the amount of bytes that are in our receive window
// (how much data we can receive into this stream).
receiveWindow uint32
// current receive window size limit. Exponentially increase it when it's exhausted
receiveWindowCurrentMax uint32
// hard limit set in http2 spec. 2^31-1
receiveWindowMax uint32
// The desired size increment for receiveWindow.
// If this is nonzero, a WINDOW_UPDATE frame needs to be sent.
windowUpdate uint32
// The headers that were most recently received.
// Particularly:
// * for an eyeball-initiated stream (as passed to TunnelHandler::ServeStream),
// these are the request headers
// * for a cloudflared-initiated stream (as created by Register/UnregisterTunnel),
// these are the response headers.
// They are useful in both of these contexts; hence `Headers` is public.
Headers []Header
// For use in the context of a cloudflared-initiated stream.
responseHeadersReceived chan struct{}
// The "Send" end of the stream
writeLock sync.Mutex
writeBuffer ReadWriteLengther
// The maximum capacity that the send buffer should grow to.
writeBufferMaxLen int
// A channel to be notified when the send buffer is not full.
writeBufferHasSpace chan struct{}
// This is the amount of bytes that are in the peer's receive window
// (how much data we can send from this stream).
sendWindow uint32
// Reference to the muxer's readyList; signal this for stream data to be sent.
readyList *ReadyList
// The headers that should be sent, and a flag so we only send them once.
headersSent bool
writeHeaders []Header
// EOF-related fields
// true if the write end of this stream has been closed
writeEOF bool
// true if we have sent EOF to the peer
sentEOF bool
// true if the peer sent us an EOF
receivedEOF bool
// Compression-related fields
receivedUseDict bool
method string
contentType string
path string
dictionaries h2Dictionaries
}
func (s *MuxedStream) Read(p []byte) (n int, err error) {
var readBuffer ReadWriteClosedCloser
if s.dictionaries.read != nil {
s.readBufferLock.RLock()
readBuffer = s.readBuffer
s.readBufferLock.RUnlock()
} else {
readBuffer = s.readBuffer
}
n, err = readBuffer.Read(p)
s.replenishReceiveWindow(uint32(n))
return
}
// Blocks until len(p) bytes have been written to the buffer
func (s *MuxedStream) Write(p []byte) (int, error) {
// If assignDictToStream returns success, then it will have acquired the
// writeLock. Otherwise we must acquire it ourselves.
ok := assignDictToStream(s, p)
if !ok {
s.writeLock.Lock()
}
defer s.writeLock.Unlock()
if s.writeEOF {
return 0, io.EOF
}
totalWritten := 0
for totalWritten < len(p) {
// If the buffer is full, block till there is more room.
// Use a loop to recheck the buffer size after the lock is reacquired.
for s.writeBufferMaxLen <= s.writeBuffer.Len() {
s.writeLock.Unlock()
<-s.writeBufferHasSpace
s.writeLock.Lock()
}
amountToWrite := len(p) - totalWritten
spaceAvailable := s.writeBufferMaxLen - s.writeBuffer.Len()
if spaceAvailable < amountToWrite {
amountToWrite = spaceAvailable
}
amountWritten, err := s.writeBuffer.Write(p[totalWritten : totalWritten+amountToWrite])
totalWritten += amountWritten
if err != nil {
return totalWritten, err
}
s.writeNotify()
}
return totalWritten, nil
}
func (s *MuxedStream) Close() error {
// TUN-115: Close the write buffer before the read buffer.
// In the case of shutdown, read will not get new data, but the write buffer can still receive
// new data. Closing read before write allows application to race between a failed read and a
// successful write, even though this close should appear to be atomic.
// This can't happen the other way because reads may succeed after a failed write; if we read
// past EOF the application will block until we close the buffer.
err := s.CloseWrite()
if err != nil {
if s.CloseRead() == nil {
// don't bother the caller with errors if at least one close succeeded
return nil
}
return err
}
return s.CloseRead()
}
func (s *MuxedStream) CloseRead() error {
return s.readBuffer.Close()
}
func (s *MuxedStream) CloseWrite() error {
s.writeLock.Lock()
defer s.writeLock.Unlock()
if s.writeEOF {
return io.EOF
}
s.writeEOF = true
if c, ok := s.writeBuffer.(io.Closer); ok {
c.Close()
}
s.writeNotify()
return nil
}
func (s *MuxedStream) WriteHeaders(headers []Header) error {
s.writeLock.Lock()
defer s.writeLock.Unlock()
if s.writeHeaders != nil {
return ErrStreamHeadersSent
}
if s.dictionaries.write != nil {
dictWriter := s.dictionaries.write.getDictWriter(s, headers)
if dictWriter != nil {
s.writeBuffer = dictWriter
}
}
s.writeHeaders = headers
s.headersSent = false
s.writeNotify()
return nil
}
func (s *MuxedStream) getReceiveWindow() uint32 {
s.writeLock.Lock()
defer s.writeLock.Unlock()
return s.receiveWindow
}
func (s *MuxedStream) getSendWindow() uint32 {
s.writeLock.Lock()
defer s.writeLock.Unlock()
return s.sendWindow
}
// writeNotify must happen while holding writeLock.
func (s *MuxedStream) writeNotify() {
s.readyList.Signal(s.streamID)
}
// Call by muxreader when it gets a WindowUpdateFrame. This is an update of the peer's
// receive window (how much data we can send).
func (s *MuxedStream) replenishSendWindow(bytes uint32) {
s.writeLock.Lock()
defer s.writeLock.Unlock()
s.sendWindow += bytes
s.writeNotify()
}
// Call by muxreader when it receives a data frame
func (s *MuxedStream) consumeReceiveWindow(bytes uint32) bool {
s.writeLock.Lock()
defer s.writeLock.Unlock()
// received data size is greater than receive window/buffer
if s.receiveWindow < bytes {
return false
}
s.receiveWindow -= bytes
if s.receiveWindow < s.receiveWindowCurrentMax/2 && s.receiveWindowCurrentMax < s.receiveWindowMax {
// exhausting client send window (how much data client can send)
// and there is room to grow the receive window
newMax := s.receiveWindowCurrentMax << 1
if newMax > s.receiveWindowMax {
newMax = s.receiveWindowMax
}
s.windowUpdate += newMax - s.receiveWindowCurrentMax
s.receiveWindowCurrentMax = newMax
// notify MuxWriter to write WINDOW_UPDATE frame
s.writeNotify()
}
return true
}
// Arranges for the MuxWriter to send a WINDOW_UPDATE
// Called by MuxedStream::Read when data has left the read buffer.
func (s *MuxedStream) replenishReceiveWindow(bytes uint32) {
s.writeLock.Lock()
defer s.writeLock.Unlock()
s.windowUpdate += bytes
s.writeNotify()
}
// receiveEOF should be called when the peer indicates no more data will be sent.
// Returns true if the socket is now closed (i.e. the write side is already closed).
func (s *MuxedStream) receiveEOF() (closed bool) {
s.writeLock.Lock()
defer s.writeLock.Unlock()
s.receivedEOF = true
s.CloseRead()
return s.writeEOF && s.writeBuffer.Len() == 0
}
func (s *MuxedStream) gotReceiveEOF() bool {
s.writeLock.Lock()
defer s.writeLock.Unlock()
return s.receivedEOF
}
// MuxedStreamReader implements io.ReadCloser for the read end of the stream.
// This is useful for passing to functions that close the object after it is done reading,
// but you still want to be able to write data afterwards (e.g. http.Client).
type MuxedStreamReader struct {
*MuxedStream
}
func (s MuxedStreamReader) Read(p []byte) (n int, err error) {
return s.MuxedStream.Read(p)
}
func (s MuxedStreamReader) Close() error {
return s.MuxedStream.CloseRead()
}
// streamChunk represents a chunk of data to be written.
type streamChunk struct {
streamID uint32
// true if a HEADERS frame should be sent
sendHeaders bool
headers []Header
// nonzero if a WINDOW_UPDATE frame should be sent;
// in that case, it is the increment value to use
windowUpdate uint32
// true if data frames should be sent
sendData bool
eof bool
buffer bytes.Buffer
}
// getChunk atomically extracts a chunk of data to be written by MuxWriter.
// The data returned will not exceed the send window for this stream.
func (s *MuxedStream) getChunk() *streamChunk {
s.writeLock.Lock()
defer s.writeLock.Unlock()
chunk := &streamChunk{
streamID: s.streamID,
sendHeaders: !s.headersSent,
headers: s.writeHeaders,
windowUpdate: s.windowUpdate,
sendData: !s.sentEOF,
eof: s.writeEOF && uint32(s.writeBuffer.Len()) <= s.sendWindow,
}
// Copy at most s.sendWindow bytes, adjust the sendWindow accordingly
writeLen, _ := io.CopyN(&chunk.buffer, s.writeBuffer, int64(s.sendWindow))
s.sendWindow -= uint32(writeLen)
// Non-blocking channel send. This will allow MuxedStream::Write() to continue, if needed
if s.writeBuffer.Len() < s.writeBufferMaxLen {
select {
case s.writeBufferHasSpace <- struct{}{}:
default:
}
}
// When we write the chunk, we'll write the WINDOW_UPDATE frame if needed
s.receiveWindow += s.windowUpdate
s.windowUpdate = 0
// When we write the chunk, we'll write the headers if needed
s.headersSent = true
// if this chunk contains the end of the stream, close the stream now
if chunk.sendData && chunk.eof {
s.sentEOF = true
}
return chunk
}
func (c *streamChunk) sendHeadersFrame() bool {
return c.sendHeaders
}
func (c *streamChunk) sendWindowUpdateFrame() bool {
return c.windowUpdate > 0
}
func (c *streamChunk) sendDataFrame() bool {
return c.sendData
}
func (c *streamChunk) nextDataFrame(frameSize int) (payload []byte, endStream bool) {
payload = c.buffer.Next(frameSize)
if c.buffer.Len() == 0 {
// this is the last data frame in this chunk
c.sendData = false
if c.eof {
endStream = true
}
}
return
}