From 006488daf2c54a0e59d14855ad6f58a8127761fb Mon Sep 17 00:00:00 2001
From: backkem <mail@backkem.me>
Date: Sun, 28 Jul 2019 18:02:37 +0200
Subject: [PATCH] Workaround for packet based DataChannel.

---
 conn.go              | 35 +++++++++++++++++++++++++++++++++--
 webrtcdirect_test.go |  2 +-
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/conn.go b/conn.go
index ef5891d..37aeb65 100644
--- a/conn.go
+++ b/conn.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"math"
 	"net"
 	"net/http"
 	"sync"
@@ -252,7 +253,7 @@ func (c *Conn) getMuxed() (smux.MuxedConn, error) {
 		}
 	}
 
-	err := c.useMuxer(&dcWrapper{rawDC, c.config.addr}, c.config.transport.muxer)
+	err := c.useMuxer(&dcWrapper{channel: rawDC, addr: c.config.addr, buf: make([]byte, dcWrapperBufSize)}, c.config.transport.muxer)
 	if err != nil {
 		return nil, err
 	}
@@ -356,17 +357,47 @@ func (c *Conn) Transport() tpt.Transport {
 	return c.config.transport
 }
 
+// Limit message size until we have a better
+// packetizing strategy.
+const dcWrapperBufSize = math.MaxUint16
+
 // dcWrapper wraps datachannel.ReadWriteCloser to form a net.Conn
 type dcWrapper struct {
 	channel datachannel.ReadWriteCloser
 	addr    net.Addr
+
+	buf      []byte
+	bufStart int
+	bufEnd   int
 }
 
 func (w *dcWrapper) Read(p []byte) (int, error) {
-	return w.channel.Read(p)
+	var err error
+
+	if w.bufEnd == 0 {
+		n := 0
+		n, err = w.channel.Read(w.buf)
+		w.bufEnd = n
+	}
+
+	n := 0
+	if w.bufEnd-w.bufStart > 0 {
+		n = copy(p, w.buf[w.bufStart:w.bufEnd])
+		w.bufStart += n
+
+		if w.bufStart >= w.bufEnd {
+			w.bufStart = 0
+			w.bufEnd = 0
+		}
+	}
+
+	return n, err
 }
 
 func (w *dcWrapper) Write(p []byte) (n int, err error) {
+	if len(p) > dcWrapperBufSize {
+		return w.channel.Write(p[:dcWrapperBufSize])
+	}
 	return w.channel.Write(p)
 }
 
diff --git a/webrtcdirect_test.go b/webrtcdirect_test.go
index fd407d2..bbd39a6 100644
--- a/webrtcdirect_test.go
+++ b/webrtcdirect_test.go
@@ -24,7 +24,7 @@ func TestTransport(t *testing.T) {
 
 	addr := "/ip4/127.0.0.1/tcp/0/http/p2p-webrtc-direct"
 
-	// TODO: Re-enable the entire test suite
+	// TODO: Re-enable normal test suite when not hitting CI limits when using race detector
 	// utils.SubtestTransport(t, ta, tb, addr, "peerA")
 	SubtestTransport(t, ta, tb, addr, "peerA")
 }