fixes, meaningful error messages and new features

src/go-proxy/io.go

@@ -0,0 +1,100 @@
+package main
+
+import (
+	"context"
+	"io"
+	"sync"
+)
+
+type ReadCloser struct {
+	ctx context.Context
+	r   io.ReadCloser
+}
+
+func (r *ReadCloser) Read(p []byte) (int, error) {
+	select {
+	case <-r.ctx.Done():
+		return 0, r.ctx.Err()
+	default:
+		return r.r.Read(p)
+	}
+}
+
+func (r *ReadCloser) Close() error {
+	return r.r.Close()
+}
+
+type Pipe struct {
+	r      ReadCloser
+	w      io.WriteCloser
+	wg     sync.WaitGroup
+	ctx    context.Context
+	cancel context.CancelFunc
+}
+
+func NewPipe(ctx context.Context, r io.ReadCloser, w io.WriteCloser) *Pipe {
+	ctx, cancel := context.WithCancel(ctx)
+	return &Pipe{
+		r:      ReadCloser{ctx, r},
+		w:      w,
+		ctx:    ctx,
+		cancel: cancel,
+	}
+}
+
+func (p *Pipe) Start() {
+	p.wg.Add(1)
+	go func() {
+		Copy(p.ctx, p.w, &p.r)
+		p.wg.Done()
+	}()
+}
+
+func (p *Pipe) Stop() {
+	p.cancel()
+	p.wg.Wait()
+}
+
+func (p *Pipe) Close() (error, error) {
+	return p.r.Close(), p.w.Close()
+}
+
+func (p *Pipe) Wait() {
+	p.wg.Wait()
+}
+
+type BidirectionalPipe struct {
+	pSrcDst Pipe
+	pDstSrc Pipe
+}
+
+func NewBidirectionalPipe(ctx context.Context, rw1 io.ReadWriteCloser, rw2 io.ReadWriteCloser) *BidirectionalPipe {
+	return &BidirectionalPipe{
+		pSrcDst: *NewPipe(ctx, rw1, rw2),
+		pDstSrc: *NewPipe(ctx, rw2, rw1),
+	}
+}
+
+func (p *BidirectionalPipe) Start() {
+	p.pSrcDst.Start()
+	p.pDstSrc.Start()
+}
+
+func (p *BidirectionalPipe) Stop() {
+	p.pSrcDst.Stop()
+	p.pDstSrc.Stop()
+}
+
+func (p *BidirectionalPipe) Close() (error, error) {
+	return p.pSrcDst.Close()
+}
+
+func (p *BidirectionalPipe) Wait() {
+	p.pSrcDst.Wait()
+	p.pDstSrc.Wait()
+}
+
+func Copy(ctx context.Context, dst io.WriteCloser, src io.ReadCloser) error {
+	_, err := io.Copy(dst, &ReadCloser{ctx, src})
+	return err
+}