From 731a926172dfd043a00ec2015f07af8f4970f7f1 Mon Sep 17 00:00:00 2001
From: Yawning Angel <yawning@schwanenlied.me>
Date: Wed, 14 May 2014 06:27:41 +0000
Subject: Implement the io.WriterTo interface.

---
 packet.go | 33 +++++++++++++++++++++++++--------
 1 file changed, 25 insertions(+), 8 deletions(-)

(limited to 'packet.go')

diff --git a/packet.go b/packet.go
index 6726ed4..8fb53d0 100644
--- a/packet.go
+++ b/packet.go
@@ -30,6 +30,7 @@ package obfs4
 import (
 	"encoding/binary"
 	"fmt"
+	"io"
 	"syscall"
 
 	"github.com/yawning/obfs4/framing"
@@ -101,24 +102,26 @@ func (c *Obfs4Conn) makeAndEncryptPacket(pktType uint8, data []byte, padLen uint
 	return n, frame, err
 }
 
-func (c *Obfs4Conn) consumeFramedPackets() (err error) {
+func (c *Obfs4Conn) consumeFramedPackets(w io.Writer) (n int, err error) {
 	if !c.isOk {
-		return syscall.EINVAL
+		return n, syscall.EINVAL
 	}
 
 	var buf [consumeReadSize]byte
-	n, err := c.conn.Read(buf[:])
+	rdLen, err := c.conn.Read(buf[:])
 	if err != nil {
 		return
 	}
-	c.receiveBuffer.Write(buf[:n])
+	c.receiveBuffer.Write(buf[:rdLen])
 
 	for c.receiveBuffer.Len() > 0 {
 		// Decrypt an AEAD frame.
-		_, pkt, err := c.decoder.Decode(&c.receiveBuffer)
+		// TODO: Change decode to write into packet directly
+		var pkt []byte
+		_, pkt, err = c.decoder.Decode(&c.receiveBuffer)
 		if err == framing.ErrAgain {
 			// The accumulated payload does not make up a full frame.
-			return nil
+			return
 		} else if err != nil {
 			break
 		} else if len(pkt) < packetOverhead {
@@ -138,12 +141,26 @@ func (c *Obfs4Conn) consumeFramedPackets() (err error) {
 		switch pktType {
 		case packetTypePayload:
 			if payloadLen > 0 {
-				c.receiveDecodedBuffer.Write(payload)
+				if w != nil {
+					// c.WriteTo() skips buffering in c.receiveDecodedBuffer
+					wrLen, err := w.Write(payload)
+					n += wrLen
+					if wrLen < int(payloadLen) {
+						err = io.ErrShortWrite
+						break
+					} else if err != nil {
+						break
+					}
+				} else {
+					// c.Read() stashes decoded payload in receiveDecodedBuffer
+					c.receiveDecodedBuffer.Write(payload)
+					n += int(payloadLen)
+				}
 			}
 		case packetTypePrngSeed:
 			// Only regenerate the distribution if we are the client.
 			if len(payload) >= distSeedLength && !c.isServer {
-				c.probDist.reset(payload[:distSeedLength])
+				c.lenProbDist.reset(payload[:distSeedLength])
 			}
 		default:
 			// Ignore unrecognised packet types.
-- 
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