From b1de1da318631c6d29f6c04dea370f712078f443 Mon Sep 17 00:00:00 2001
From: Ting-Yu Wang <anivia@google.com>
Date: Thu, 7 Jan 2021 14:14:58 -0800
Subject: netstack: Refactor tcpip.Endpoint.Read

Read now takes a destination io.Writer, count, options. Keeping the method name
Read, in contrast to the Write method.

This enables:
* direct transfer of views under VV
* zero copy

It also eliminates the need for sentry to keep a slice of view because
userspace had requested a read that is smaller than the view returned, removing
the complexity there.

Read/Peek/ReadPacket are now consolidated together and some duplicate code is
removed.

PiperOrigin-RevId: 350636322
---
 pkg/tcpip/sample/tun_tcp_connect/main.go | 5 ++---
 pkg/tcpip/sample/tun_tcp_echo/main.go    | 7 +++++--
 2 files changed, 7 insertions(+), 5 deletions(-)

(limited to 'pkg/tcpip/sample')

diff --git a/pkg/tcpip/sample/tun_tcp_connect/main.go b/pkg/tcpip/sample/tun_tcp_connect/main.go
index 51d428049..4777163cd 100644
--- a/pkg/tcpip/sample/tun_tcp_connect/main.go
+++ b/pkg/tcpip/sample/tun_tcp_connect/main.go
@@ -44,6 +44,7 @@ import (
 	"bufio"
 	"fmt"
 	"log"
+	"math"
 	"math/rand"
 	"net"
 	"os"
@@ -200,7 +201,7 @@ func main() {
 	// connection from its side.
 	wq.EventRegister(&waitEntry, waiter.EventIn)
 	for {
-		v, _, err := ep.Read(nil)
+		_, err := ep.Read(os.Stdout, math.MaxUint16, tcpip.ReadOptions{})
 		if err != nil {
 			if err == tcpip.ErrClosedForReceive {
 				break
@@ -213,8 +214,6 @@ func main() {
 
 			log.Fatal("Read() failed:", err)
 		}
-
-		os.Stdout.Write(v)
 	}
 	wq.EventUnregister(&waitEntry)
 
diff --git a/pkg/tcpip/sample/tun_tcp_echo/main.go b/pkg/tcpip/sample/tun_tcp_echo/main.go
index 1c2afd554..a80fa0474 100644
--- a/pkg/tcpip/sample/tun_tcp_echo/main.go
+++ b/pkg/tcpip/sample/tun_tcp_echo/main.go
@@ -20,8 +20,10 @@
 package main
 
 import (
+	"bytes"
 	"flag"
 	"log"
+	"math"
 	"math/rand"
 	"net"
 	"os"
@@ -54,7 +56,8 @@ func echo(wq *waiter.Queue, ep tcpip.Endpoint) {
 	defer wq.EventUnregister(&waitEntry)
 
 	for {
-		v, _, err := ep.Read(nil)
+		var buf bytes.Buffer
+		_, err := ep.Read(&buf, math.MaxUint16, tcpip.ReadOptions{})
 		if err != nil {
 			if err == tcpip.ErrWouldBlock {
 				<-notifyCh
@@ -64,7 +67,7 @@ func echo(wq *waiter.Queue, ep tcpip.Endpoint) {
 			return
 		}
 
-		ep.Write(tcpip.SlicePayload(v), tcpip.WriteOptions{})
+		ep.Write(tcpip.SlicePayload(buf.Bytes()), tcpip.WriteOptions{})
 	}
 }
 
-- 
cgit v1.2.3