From 1cbfeea0cd8eb4ba21b83dea08f589514925bac3 Mon Sep 17 00:00:00 2001
From: Darien Raymond <admin@v2ray.com>
Date: Mon, 12 Mar 2018 22:10:13 +0100
Subject: [PATCH] simplify NewSize calls

---
 app/proxyman/mux/reader.go |  7 +------
 common/crypto/auth.go      |  7 +------
 proxy/shadowsocks/ota.go   | 20 ++++++--------------
 3 files changed, 8 insertions(+), 26 deletions(-)

diff --git a/app/proxyman/mux/reader.go b/app/proxyman/mux/reader.go
index 33453b71..b2e1a411 100644
--- a/app/proxyman/mux/reader.go
+++ b/app/proxyman/mux/reader.go
@@ -51,12 +51,7 @@ func (r *PacketReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
 		return nil, err
 	}
 
-	var b *buf.Buffer
-	if size <= buf.Size {
-		b = buf.New()
-	} else {
-		b = buf.NewSize(uint32(size))
-	}
+	b := buf.NewSize(uint32(size))
 	if err := b.AppendSupplier(buf.ReadFullFrom(r.reader, int(size))); err != nil {
 		b.Release()
 		return nil, err
diff --git a/common/crypto/auth.go b/common/crypto/auth.go
index ecdb0189..84f5b41a 100644
--- a/common/crypto/auth.go
+++ b/common/crypto/auth.go
@@ -124,12 +124,7 @@ func (r *AuthenticationReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
 		return nil, io.EOF
 	}
 
-	var b *buf.Buffer
-	if size <= buf.Size {
-		b = buf.New()
-	} else {
-		b = buf.NewSize(uint32(size))
-	}
+	b := buf.NewSize(uint32(size))
 	if err := b.Reset(buf.ReadFullFrom(r.reader, size)); err != nil {
 		b.Release()
 		return nil, err
diff --git a/proxy/shadowsocks/ota.go b/proxy/shadowsocks/ota.go
index d1015e0f..be18be8c 100644
--- a/proxy/shadowsocks/ota.go
+++ b/proxy/shadowsocks/ota.go
@@ -70,22 +70,14 @@ func NewChunkReader(reader io.Reader, auth *Authenticator) *ChunkReader {
 }
 
 func (v *ChunkReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
-	buffer := buf.New()
-	if err := buffer.AppendSupplier(buf.ReadFullFrom(v.reader, 2)); err != nil {
-		buffer.Release()
-		return nil, err
-	}
-	// There is a potential buffer overflow here. Large buffer is 64K bytes,
-	// while uin16 + 10 will be more than that
-	length := serial.BytesToUint16(buffer.BytesTo(2)) + AuthSize
-	if length > buf.Size {
-		// Theoretically the size of a chunk is 64K, but most Shadowsocks implementations used <4K buffer.
-		buffer.Release()
-		buffer = buf.NewSize(uint32(length) + 128)
+	size, err := serial.ReadUint16(v.reader)
+	if err != nil {
+		return nil, newError("failed to read size")
 	}
+	size += AuthSize
 
-	buffer.Clear()
-	if err := buffer.AppendSupplier(buf.ReadFullFrom(v.reader, int(length))); err != nil {
+	buffer := buf.NewSize(uint32(size))
+	if err := buffer.AppendSupplier(buf.ReadFullFrom(v.reader, int(size))); err != nil {
 		buffer.Release()
 		return nil, err
 	}