chore: refresh gramsrv public release

internal/sfu/demux.go

@@ -0,0 +1,108 @@
+package sfu
+
+import (
+	"errors"
+	"io"
+	"net"
+	"time"
+
+	"github.com/pion/transport/v4/packetio"
+)
+
+// demuxer 把 ICE conn 上的混合流量按 RFC 7983 首字节分发：
+//   - [20,63]   → DTLS（握手与应用数据）
+//   - [128,191] → RTP/RTCP（再按 RTCP PT 200..207 细分）
+//
+// 写方向全部直写底层 ICE conn（同一 5 元组，RTCP-mux）。
+type demuxer struct {
+	base  net.Conn
+	dtls  *packetio.Buffer
+	srtp  *packetio.Buffer
+	srtcp *packetio.Buffer
+	done  chan struct{}
+}
+
+func newDemuxer(base net.Conn) *demuxer {
+	d := &demuxer{
+		base:  base,
+		dtls:  packetio.NewBuffer(),
+		srtp:  packetio.NewBuffer(),
+		srtcp: packetio.NewBuffer(),
+		done:  make(chan struct{}),
+	}
+	go d.readLoop()
+	return d
+}
+
+func (d *demuxer) readLoop() {
+	defer close(d.done)
+	buf := make([]byte, 1500)
+	for {
+		n, err := d.base.Read(buf)
+		if err != nil {
+			_ = d.dtls.Close()
+			_ = d.srtp.Close()
+			_ = d.srtcp.Close()
+			return
+		}
+		if n == 0 {
+			continue
+		}
+		first := buf[0]
+		switch {
+		case first >= 20 && first <= 63:
+			_, _ = d.dtls.Write(buf[:n])
+		case first >= 128 && first <= 191:
+			if n >= 2 && isRTCPPayloadType(buf[1]) {
+				_, _ = d.srtcp.Write(buf[:n])
+			} else {
+				_, _ = d.srtp.Write(buf[:n])
+			}
+		default:
+			// STUN 已被 ICE 层消费；其余丢弃。
+		}
+	}
+}
+
+func isRTCPPayloadType(pt byte) bool {
+	// RTCP packet type 范围（SR/RR/SDES/BYE/APP/RTPFB/PSFB...）。
+	return pt >= 192 && pt <= 223
+}
+
+func (d *demuxer) Close() {
+	_ = d.dtls.Close()
+	_ = d.srtp.Close()
+	_ = d.srtcp.Close()
+}
+
+// demuxConn 把单一 buffer 包成 net.Conn：读取自 buffer，写直达底层。
+type demuxConn struct {
+	buf  *packetio.Buffer
+	base net.Conn
+}
+
+func (c *demuxConn) Read(b []byte) (int, error) {
+	n, err := c.buf.Read(b)
+	if errors.Is(err, io.EOF) || errors.Is(err, packetio.ErrFull) {
+		return n, err
+	}
+	return n, err
+}
+
+func (c *demuxConn) Write(b []byte) (int, error) { return c.base.Write(b) }
+func (c *demuxConn) Close() error                { return c.buf.Close() }
+func (c *demuxConn) LocalAddr() net.Addr         { return c.base.LocalAddr() }
+func (c *demuxConn) RemoteAddr() net.Addr        { return c.base.RemoteAddr() }
+
+// SetDeadline/SetReadDeadline 透传给 packetio.Buffer：DTLS 握手依赖读超时
+// 推进重传与失败退出（pion/dtls v3 默认 Handshake 无限期阻塞，调用方必须
+// 在握手期间设硬上限，否则停滞的握手会把 goroutine 挂死）。
+func (c *demuxConn) SetDeadline(t time.Time) error     { return c.buf.SetReadDeadline(t) }
+func (c *demuxConn) SetReadDeadline(t time.Time) error { return c.buf.SetReadDeadline(t) }
+
+// 写方向直达底层 ICE conn，无队列可超时。
+func (c *demuxConn) SetWriteDeadline(t time.Time) error { return nil }
+
+func (d *demuxer) dtlsConn() net.Conn  { return &demuxConn{buf: d.dtls, base: d.base} }
+func (d *demuxer) srtpConn() net.Conn  { return &demuxConn{buf: d.srtp, base: d.base} }
+func (d *demuxer) srtcpConn() net.Conn { return &demuxConn{buf: d.srtcp, base: d.base} }