mirror of
https://github.com/caddyserver/caddy.git
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224 lines
6.2 KiB
Go
224 lines
6.2 KiB
Go
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// Copyright 2015 Matthew Holt and The Caddy Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Most of the code in this file was initially borrowed from the Go
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// standard library, which has this copyright notice:
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// Copyright 2011 The Go Authors.
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package reverseproxy
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import (
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"context"
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"io"
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"net/http"
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"sync"
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"time"
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)
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func (h Handler) handleUpgradeResponse(rw http.ResponseWriter, req *http.Request, res *http.Response) {
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reqUpType := upgradeType(req.Header)
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resUpType := upgradeType(res.Header)
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if reqUpType != resUpType {
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// TODO: figure out our own error handling
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// p.getErrorHandler()(rw, req, fmt.Errorf("backend tried to switch protocol %q when %q was requested", resUpType, reqUpType))
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return
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}
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copyHeader(res.Header, rw.Header())
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hj, ok := rw.(http.Hijacker)
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if !ok {
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// p.getErrorHandler()(rw, req, fmt.Errorf("can't switch protocols using non-Hijacker ResponseWriter type %T", rw))
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return
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}
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backConn, ok := res.Body.(io.ReadWriteCloser)
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if !ok {
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// p.getErrorHandler()(rw, req, fmt.Errorf("internal error: 101 switching protocols response with non-writable body"))
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return
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}
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defer backConn.Close()
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conn, brw, err := hj.Hijack()
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if err != nil {
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// p.getErrorHandler()(rw, req, fmt.Errorf("Hijack failed on protocol switch: %v", err))
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return
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}
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defer conn.Close()
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res.Body = nil // so res.Write only writes the headers; we have res.Body in backConn above
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if err := res.Write(brw); err != nil {
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// p.getErrorHandler()(rw, req, fmt.Errorf("response write: %v", err))
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return
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}
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if err := brw.Flush(); err != nil {
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// p.getErrorHandler()(rw, req, fmt.Errorf("response flush: %v", err))
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return
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}
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errc := make(chan error, 1)
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spc := switchProtocolCopier{user: conn, backend: backConn}
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go spc.copyToBackend(errc)
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go spc.copyFromBackend(errc)
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<-errc
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return
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}
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// flushInterval returns the p.FlushInterval value, conditionally
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// overriding its value for a specific request/response.
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func (h Handler) flushInterval(req *http.Request, res *http.Response) time.Duration {
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resCT := res.Header.Get("Content-Type")
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// For Server-Sent Events responses, flush immediately.
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// The MIME type is defined in https://www.w3.org/TR/eventsource/#text-event-stream
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if resCT == "text/event-stream" {
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return -1 // negative means immediately
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}
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// TODO: more specific cases? e.g. res.ContentLength == -1? (this TODO is from the std lib)
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return time.Duration(h.FlushInterval)
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}
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func (h Handler) copyResponse(dst io.Writer, src io.Reader, flushInterval time.Duration) error {
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if flushInterval != 0 {
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if wf, ok := dst.(writeFlusher); ok {
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mlw := &maxLatencyWriter{
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dst: wf,
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latency: flushInterval,
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}
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defer mlw.stop()
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dst = mlw
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}
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}
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// TODO: Figure out how we want to do this... using custom buffer pool type seems unnecessary
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// or maybe it is, depending on how we want to handle errors,
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// see: https://github.com/golang/go/issues/21814
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// buf := bufPool.Get().(*bytes.Buffer)
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// buf.Reset()
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// defer bufPool.Put(buf)
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// _, err := io.CopyBuffer(dst, src, )
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var buf []byte
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// if h.BufferPool != nil {
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// buf = h.BufferPool.Get()
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// defer h.BufferPool.Put(buf)
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// }
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_, err := h.copyBuffer(dst, src, buf)
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return err
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}
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// copyBuffer returns any write errors or non-EOF read errors, and the amount
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// of bytes written.
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func (h Handler) copyBuffer(dst io.Writer, src io.Reader, buf []byte) (int64, error) {
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if len(buf) == 0 {
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buf = make([]byte, 32*1024)
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}
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var written int64
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for {
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nr, rerr := src.Read(buf)
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if rerr != nil && rerr != io.EOF && rerr != context.Canceled {
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// TODO: this could be useful to know (indeed, it revealed an error in our
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// fastcgi PoC earlier; but it's this single error report here that necessitates
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// a function separate from io.CopyBuffer, since io.CopyBuffer does not distinguish
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// between read or write errors; in a reverse proxy situation, write errors are not
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// something we need to report to the client, but read errors are a problem on our
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// end for sure. so we need to decide what we want.)
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// p.logf("copyBuffer: ReverseProxy read error during body copy: %v", rerr)
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}
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if nr > 0 {
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nw, werr := dst.Write(buf[:nr])
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if nw > 0 {
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written += int64(nw)
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}
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if werr != nil {
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return written, werr
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}
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if nr != nw {
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return written, io.ErrShortWrite
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}
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}
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if rerr != nil {
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if rerr == io.EOF {
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rerr = nil
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}
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return written, rerr
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}
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}
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}
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type writeFlusher interface {
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io.Writer
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http.Flusher
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}
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type maxLatencyWriter struct {
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dst writeFlusher
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latency time.Duration // non-zero; negative means to flush immediately
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mu sync.Mutex // protects t, flushPending, and dst.Flush
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t *time.Timer
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flushPending bool
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}
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func (m *maxLatencyWriter) Write(p []byte) (n int, err error) {
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m.mu.Lock()
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defer m.mu.Unlock()
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n, err = m.dst.Write(p)
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if m.latency < 0 {
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m.dst.Flush()
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return
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}
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if m.flushPending {
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return
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}
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if m.t == nil {
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m.t = time.AfterFunc(m.latency, m.delayedFlush)
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} else {
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m.t.Reset(m.latency)
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}
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m.flushPending = true
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return
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}
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func (m *maxLatencyWriter) delayedFlush() {
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m.mu.Lock()
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defer m.mu.Unlock()
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if !m.flushPending { // if stop was called but AfterFunc already started this goroutine
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return
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}
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m.dst.Flush()
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m.flushPending = false
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}
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func (m *maxLatencyWriter) stop() {
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m.mu.Lock()
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defer m.mu.Unlock()
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m.flushPending = false
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if m.t != nil {
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m.t.Stop()
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}
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}
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// switchProtocolCopier exists so goroutines proxying data back and
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// forth have nice names in stacks.
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type switchProtocolCopier struct {
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user, backend io.ReadWriter
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}
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func (c switchProtocolCopier) copyFromBackend(errc chan<- error) {
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_, err := io.Copy(c.user, c.backend)
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errc <- err
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}
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func (c switchProtocolCopier) copyToBackend(errc chan<- error) {
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_, err := io.Copy(c.backend, c.user)
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errc <- err
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}
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