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

29 files changed, 794 insertions, 510 deletions

diff --git a/pkg/tcpip/adapters/gonet/gonet.go b/pkg/tcpip/adapters/gonet/gonet.go
index 4f551cd92..7193f56ad 100644
--- a/pkg/tcpip/adapters/gonet/gonet.go
+++ b/pkg/tcpip/adapters/gonet/gonet.go
@@ -286,45 +286,47 @@ type opErrorer interface {
 
 // commonRead implements the common logic between net.Conn.Read and
 // net.PacketConn.ReadFrom.
-func commonRead(ep tcpip.Endpoint, wq *waiter.Queue, deadline <-chan struct{}, addr *tcpip.FullAddress, errorer opErrorer, dontWait bool) ([]byte, error) {
+func commonRead(b []byte, ep tcpip.Endpoint, wq *waiter.Queue, deadline <-chan struct{}, addr *tcpip.FullAddress, errorer opErrorer) (int, error) {
 	select {
 	case <-deadline:
-		return nil, errorer.newOpError("read", &timeoutError{})
+		return 0, errorer.newOpError("read", &timeoutError{})
 	default:
 	}
 
-	read, _, err := ep.Read(addr)
+	w := tcpip.SliceWriter(b)
+	opts := tcpip.ReadOptions{NeedRemoteAddr: addr != nil}
+	res, err := ep.Read(&w, len(b), opts)
 
 	if err == tcpip.ErrWouldBlock {
-		if dontWait {
-			return nil, errWouldBlock
-		}
 		// Create wait queue entry that notifies a channel.
 		waitEntry, notifyCh := waiter.NewChannelEntry(nil)
 		wq.EventRegister(&waitEntry, waiter.EventIn)
 		defer wq.EventUnregister(&waitEntry)
 		for {
-			read, _, err = ep.Read(addr)
+			res, err = ep.Read(&w, len(b), opts)
 			if err != tcpip.ErrWouldBlock {
 				break
 			}
 			select {
 			case <-deadline:
-				return nil, errorer.newOpError("read", &timeoutError{})
+				return 0, errorer.newOpError("read", &timeoutError{})
 			case <-notifyCh:
 			}
 		}
 	}
 
 	if err == tcpip.ErrClosedForReceive {
-		return nil, io.EOF
+		return 0, io.EOF
 	}
 
 	if err != nil {
-		return nil, errorer.newOpError("read", errors.New(err.String()))
+		return 0, errorer.newOpError("read", errors.New(err.String()))
 	}
 
-	return read, nil
+	if addr != nil {
+		*addr = res.RemoteAddr
+	}
+	return res.Count, nil
 }
 
 // Read implements net.Conn.Read.
@@ -334,31 +336,11 @@ func (c *TCPConn) Read(b []byte) (int, error) {
 
 	deadline := c.readCancel()
 
-	numRead := 0
-	defer func() {
-		if numRead != 0 {
-			c.ep.ModerateRecvBuf(numRead)
-		}
-	}()
-	for numRead != len(b) {
-		if len(c.read) == 0 {
-			var err error
-			c.read, err = commonRead(c.ep, c.wq, deadline, nil, c, numRead != 0)
-			if err != nil {
-				if numRead != 0 {
-					return numRead, nil
-				}
-				return numRead, err
-			}
-		}
-		n := copy(b[numRead:], c.read)
-		c.read.TrimFront(n)
-		numRead += n
-		if len(c.read) == 0 {
-			c.read = nil
-		}
+	n, err := commonRead(b, c.ep, c.wq, deadline, nil, c)
+	if n != 0 {
+		c.ep.ModerateRecvBuf(n)
 	}
-	return numRead, nil
+	return n, err
 }
 
 // Write implements net.Conn.Write.
@@ -652,12 +634,11 @@ func (c *UDPConn) ReadFrom(b []byte) (int, net.Addr, error) {
 	deadline := c.readCancel()
 
 	var addr tcpip.FullAddress
-	read, err := commonRead(c.ep, c.wq, deadline, &addr, c, false)
+	n, err := commonRead(b, c.ep, c.wq, deadline, &addr, c)
 	if err != nil {
 		return 0, nil, err
 	}
-
-	return copy(b, read), fullToUDPAddr(addr), nil
+	return n, fullToUDPAddr(addr), nil
 }
 
 func (c *UDPConn) Write(b []byte) (int, error) {
diff --git a/pkg/tcpip/buffer/view.go b/pkg/tcpip/buffer/view.go
index 8db70a700..5dd1b1b6b 100644
--- a/pkg/tcpip/buffer/view.go
+++ b/pkg/tcpip/buffer/view.go
@@ -105,18 +105,18 @@ func (vv *VectorisedView) TrimFront(count int) {
 }
 
 // Read implements io.Reader.
-func (vv *VectorisedView) Read(v View) (copied int, err error) {
-	count := len(v)
+func (vv *VectorisedView) Read(b []byte) (copied int, err error) {
+	count := len(b)
 	for count > 0 && len(vv.views) > 0 {
 		if count < len(vv.views[0]) {
 			vv.size -= count
-			copy(v[copied:], vv.views[0][:count])
+			copy(b[copied:], vv.views[0][:count])
 			vv.views[0].TrimFront(count)
 			copied += count
 			return copied, nil
 		}
 		count -= len(vv.views[0])
-		copy(v[copied:], vv.views[0])
+		copy(b[copied:], vv.views[0])
 		copied += len(vv.views[0])
 		vv.removeFirst()
 	}
@@ -145,6 +145,35 @@ func (vv *VectorisedView) ReadToVV(dstVV *VectorisedView, count int) (copied int
 	return copied
 }
 
+// ReadTo reads up to count bytes from vv to dst. It also removes them from vv
+// unless peek is true.
+func (vv *VectorisedView) ReadTo(dst io.Writer, count int, peek bool) (int, error) {
+	var err error
+	done := 0
+	for _, v := range vv.Views() {
+		remaining := count - done
+		if remaining <= 0 {
+			break
+		}
+		if len(v) > remaining {
+			v = v[:remaining]
+		}
+
+		var n int
+		n, err = dst.Write(v)
+		if n > 0 {
+			done += n
+		}
+		if err != nil {
+			break
+		}
+	}
+	if !peek {
+		vv.TrimFront(done)
+	}
+	return done, err
+}
+
 // CapLength irreversibly reduces the length of the vectorised view.
 func (vv *VectorisedView) CapLength(length int) {
 	if length < 0 {
diff --git a/pkg/tcpip/buffer/view_test.go b/pkg/tcpip/buffer/view_test.go
index 726e54de9..e0ef8a94d 100644
--- a/pkg/tcpip/buffer/view_test.go
+++ b/pkg/tcpip/buffer/view_test.go
@@ -235,14 +235,16 @@ func TestToClone(t *testing.T) {
 	}
 }
 
-func TestVVReadToVV(t *testing.T) {
-	testCases := []struct {
-		comment     string
-		vv          VectorisedView
-		bytesToRead int
-		wantBytes   string
-		leftVV      VectorisedView
-	}{
+type readToTestCases struct {
+	comment     string
+	vv          VectorisedView
+	bytesToRead int
+	wantBytes   string
+	leftVV      VectorisedView
+}
+
+func createReadToTestCases() []readToTestCases {
+	return []readToTestCases{
 		{
 			comment:     "large VV, short read",
 			vv:          vv(30, "012345678901234567890123456789"),
@@ -279,8 +281,10 @@ func TestVVReadToVV(t *testing.T) {
 			leftVV:      vv(0, ""),
 		},
 	}
+}
 
-	for _, tc := range testCases {
+func TestVVReadToVV(t *testing.T) {
+	for _, tc := range createReadToTestCases() {
 		t.Run(tc.comment, func(t *testing.T) {
 			var readTo VectorisedView
 			inSize := tc.vv.Size()
@@ -301,6 +305,52 @@ func TestVVReadToVV(t *testing.T) {
 	}
 }
 
+func TestVVReadTo(t *testing.T) {
+	for _, tc := range createReadToTestCases() {
+		t.Run(tc.comment, func(t *testing.T) {
+			var dst bytes.Buffer
+			origSize := tc.vv.Size()
+			copied, err := tc.vv.ReadTo(&dst, tc.bytesToRead, false /* peek */)
+			if got, want := copied, len(tc.wantBytes); err != nil || got != want {
+				t.Errorf("got ReadTo(&dst, %d, false) = %d, %v; want %d, nil", tc.bytesToRead, got, err, want)
+			}
+			if got, want := string(dst.Bytes()), tc.wantBytes; got != want {
+				t.Errorf("got dst = %q, want %q", got, want)
+			}
+			if got, want := tc.vv.Size(), origSize-copied; got != want {
+				t.Errorf("got after-read tc.vv.Size() = %d, want %d", got, want)
+			}
+			if got, want := string(tc.vv.ToView()), string(tc.leftVV.ToView()); got != want {
+				t.Errorf("got after-read data in tc.vv = %q, want %q", got, want)
+			}
+		})
+	}
+}
+
+func TestVVReadToPeek(t *testing.T) {
+	for _, tc := range createReadToTestCases() {
+		t.Run(tc.comment, func(t *testing.T) {
+			var dst bytes.Buffer
+			origSize := tc.vv.Size()
+			origData := string(tc.vv.ToView())
+			copied, err := tc.vv.ReadTo(&dst, tc.bytesToRead, true /* peek */)
+			if got, want := copied, len(tc.wantBytes); err != nil || got != want {
+				t.Errorf("got ReadTo(&dst, %d, false) = %d, %v; want %d, nil", tc.bytesToRead, got, err, want)
+			}
+			if got, want := string(dst.Bytes()), tc.wantBytes; got != want {
+				t.Errorf("got dst = %q, want %q", got, want)
+			}
+			// Expect tc.vv is unchanged.
+			if got, want := tc.vv.Size(), origSize; got != want {
+				t.Errorf("got after-read tc.vv.Size() = %d, want %d", got, want)
+			}
+			if got, want := string(tc.vv.ToView()), origData; got != want {
+				t.Errorf("got after-read data in tc.vv = %q, want %q", got, want)
+			}
+		})
+	}
+}
+
 func TestVVRead(t *testing.T) {
 	testCases := []struct {
 		comment     string
diff --git a/pkg/tcpip/checker/checker.go b/pkg/tcpip/checker/checker.go
index 91971b687..0ac2000ca 100644
--- a/pkg/tcpip/checker/checker.go
+++ b/pkg/tcpip/checker/checker.go
@@ -1603,3 +1603,15 @@ func IPv6RouterAlert(want header.IPv6RouterAlertValue) IPv6ExtHdrOptionChecker {
 		}
 	}
 }
+
+// IgnoreCmpPath returns a cmp.Option that ignores listed field paths.
+func IgnoreCmpPath(paths ...string) cmp.Option {
+	ignores := map[string]struct{}{}
+	for _, path := range paths {
+		ignores[path] = struct{}{}
+	}
+	return cmp.FilterPath(func(path cmp.Path) bool {
+		_, ok := ignores[path.String()]
+		return ok
+	}, cmp.Ignore())
+}
diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go
index ef62fe6fc..1c4919b1e 100644
--- a/pkg/tcpip/network/ipv4/ipv4_test.go
+++ b/pkg/tcpip/network/ipv4/ipv4_test.go
@@ -15,9 +15,11 @@
 package ipv4_test
 
 import (
+	"bytes"
 	"context"
 	"encoding/hex"
 	"fmt"
+	"io/ioutil"
 	"math"
 	"net"
 	"testing"
@@ -2408,18 +2410,26 @@ func TestReceiveFragments(t *testing.T) {
 				t.Errorf("got UDP Rx Packets = %d, want = %d", got, want)
 			}
 
+			const rcvSize = 65536 // Account for reassembled packets.
 			for i, expectedPayload := range test.expectedPayloads {
-				gotPayload, _, err := ep.Read(nil)
+				var buf bytes.Buffer
+				result, err := ep.Read(&buf, rcvSize, tcpip.ReadOptions{})
 				if err != nil {
-					t.Fatalf("(i=%d) Read(nil): %s", i, err)
+					t.Fatalf("(i=%d) Read: %s", i, err)
 				}
-				if diff := cmp.Diff(buffer.View(expectedPayload), gotPayload); diff != "" {
+				if diff := cmp.Diff(tcpip.ReadResult{
+					Count: len(expectedPayload),
+					Total: len(expectedPayload),
+				}, result, checker.IgnoreCmpPath("ControlMessages")); diff != "" {
+					t.Errorf("(i=%d) ep.Read: unexpected result (-want +got):\n%s", i, diff)
+				}
+				if diff := cmp.Diff(expectedPayload, buf.Bytes()); diff != "" {
 					t.Errorf("(i=%d) got UDP payload mismatch (-want +got):\n%s", i, diff)
 				}
 			}
 
-			if gotPayload, _, err := ep.Read(nil); err != tcpip.ErrWouldBlock {
-				t.Fatalf("(last) got Read(nil) = (%x, _, %v), want = (_, _, %s)", gotPayload, err, tcpip.ErrWouldBlock)
+			if res, err := ep.Read(ioutil.Discard, rcvSize, tcpip.ReadOptions{}); err != tcpip.ErrWouldBlock {
+				t.Fatalf("(last) got Read = (%v, %v), want = (_, %s)", res, err, tcpip.ErrWouldBlock)
 			}
 		})
 	}
diff --git a/pkg/tcpip/network/ipv6/ipv6_test.go b/pkg/tcpip/network/ipv6/ipv6_test.go
index 5f07d3af8..360025b20 100644
--- a/pkg/tcpip/network/ipv6/ipv6_test.go
+++ b/pkg/tcpip/network/ipv6/ipv6_test.go
@@ -15,8 +15,10 @@
 package ipv6
 
 import (
+	"bytes"
 	"encoding/hex"
 	"fmt"
+	"io/ioutil"
 	"math"
 	"net"
 	"testing"
@@ -844,13 +846,14 @@ func TestReceiveIPv6ExtHdrs(t *testing.T) {
 		},
 	}
 
+	const mtu = header.IPv6MinimumMTU
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 			s := stack.New(stack.Options{
 				NetworkProtocols:   []stack.NetworkProtocolFactory{NewProtocol},
 				TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
 			})
-			e := channel.New(1, header.IPv6MinimumMTU, linkAddr1)
+			e := channel.New(1, mtu, linkAddr1)
 			if err := s.CreateNIC(nicID, e); err != nil {
 				t.Fatalf("CreateNIC(%d, _) = %s", nicID, err)
 			}
@@ -979,17 +982,24 @@ func TestReceiveIPv6ExtHdrs(t *testing.T) {
 			if got := stats.Value(); got != 1 {
 				t.Errorf("got UDP Rx Packets = %d, want = 1", got)
 			}
-			gotPayload, _, err := ep.Read(nil)
+			var buf bytes.Buffer
+			result, err := ep.Read(&buf, mtu, tcpip.ReadOptions{})
 			if err != nil {
-				t.Fatalf("Read(nil): %s", err)
+				t.Fatalf("Read: %s", err)
+			}
+			if diff := cmp.Diff(tcpip.ReadResult{
+				Count: len(udpPayload),
+				Total: len(udpPayload),
+			}, result, checker.IgnoreCmpPath("ControlMessages")); diff != "" {
+				t.Errorf("Read: unexpected result (-want +got):\n%s", diff)
 			}
-			if diff := cmp.Diff(buffer.View(udpPayload), gotPayload); diff != "" {
+			if diff := cmp.Diff(udpPayload, buf.Bytes()); diff != "" {
 				t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff)
 			}
 
 			// Should not have any more UDP packets.
-			if gotPayload, _, err := ep.Read(nil); err != tcpip.ErrWouldBlock {
-				t.Fatalf("got Read(nil) = (%x, _, %v), want = (_, _, %s)", gotPayload, err, tcpip.ErrWouldBlock)
+			if res, err := ep.Read(ioutil.Discard, mtu, tcpip.ReadOptions{}); err != tcpip.ErrWouldBlock {
+				t.Fatalf("got Read = (%v, %v), want = (_, %s)", res, err, tcpip.ErrWouldBlock)
 			}
 		})
 	}
@@ -1969,18 +1979,20 @@ func TestReceiveIPv6Fragments(t *testing.T) {
 				t.Errorf("got UDP Rx Packets = %d, want = %d", got, want)
 			}
 
+			const rcvSize = 65536 // Account for reassembled packets.
 			for i, p := range test.expectedPayloads {
-				gotPayload, _, err := ep.Read(nil)
+				var buf bytes.Buffer
+				_, err := ep.Read(&buf, rcvSize, tcpip.ReadOptions{})
 				if err != nil {
-					t.Fatalf("(i=%d) Read(nil): %s", i, err)
+					t.Fatalf("(i=%d) Read: %s", i, err)
 				}
-				if diff := cmp.Diff(buffer.View(p), gotPayload); diff != "" {
+				if diff := cmp.Diff(p, buf.Bytes()); diff != "" {
 					t.Errorf("(i=%d) got UDP payload mismatch (-want +got):\n%s", i, diff)
 				}
 			}
 
-			if gotPayload, _, err := ep.Read(nil); err != tcpip.ErrWouldBlock {
-				t.Fatalf("(last) got Read(nil) = (%x, _, %v), want = (_, _, %s)", gotPayload, err, tcpip.ErrWouldBlock)
+			if res, err := ep.Read(ioutil.Discard, rcvSize, tcpip.ReadOptions{}); err != tcpip.ErrWouldBlock {
+				t.Fatalf("(last) got Read = (%v, %v), want = (_, %s)", res, err, tcpip.ErrWouldBlock)
 			}
 		})
 	}
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{})
 	}
 }
 
diff --git a/pkg/tcpip/stack/transport_demuxer_test.go b/pkg/tcpip/stack/transport_demuxer_test.go
index 737d8d912..859278f0b 100644
--- a/pkg/tcpip/stack/transport_demuxer_test.go
+++ b/pkg/tcpip/stack/transport_demuxer_test.go
@@ -15,6 +15,7 @@
 package stack_test
 
 import (
+	"io/ioutil"
 	"math"
 	"math/rand"
 	"testing"
@@ -351,7 +352,7 @@ func TestBindToDeviceDistribution(t *testing.T) {
 						}
 
 						ep := <-pollChannel
-						if _, _, err := ep.Read(nil); err != nil {
+						if _, err := ep.Read(ioutil.Discard, math.MaxUint16, tcpip.ReadOptions{}); err != nil {
 							t.Fatalf("Read on endpoint %d failed: %s", eps[ep], err)
 						}
 						stats[ep]++
diff --git a/pkg/tcpip/stack/transport_test.go b/pkg/tcpip/stack/transport_test.go
index dd552b8b9..a5facf578 100644
--- a/pkg/tcpip/stack/transport_test.go
+++ b/pkg/tcpip/stack/transport_test.go
@@ -15,6 +15,7 @@
 package stack_test
 
 import (
+	"io"
 	"testing"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -85,8 +86,8 @@ func (*fakeTransportEndpoint) Readiness(mask waiter.EventMask) waiter.EventMask
 	return mask
 }
 
-func (*fakeTransportEndpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
-	return buffer.View{}, tcpip.ControlMessages{}, nil
+func (*fakeTransportEndpoint) Read(io.Writer, int, tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
+	return tcpip.ReadResult{}, nil
 }
 
 func (f *fakeTransportEndpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-chan struct{}, *tcpip.Error) {
@@ -110,10 +111,6 @@ func (f *fakeTransportEndpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions
 	return int64(len(v)), nil, nil
 }
 
-func (*fakeTransportEndpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // SetSockOpt sets a socket option. Currently not supported.
 func (*fakeTransportEndpoint) SetSockOpt(tcpip.SettableSocketOption) *tcpip.Error {
 	return tcpip.ErrInvalidEndpointState
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index ef0f51f1a..f798056c0 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -31,6 +31,7 @@ package tcpip
 import (
 	"errors"
 	"fmt"
+	"io"
 	"math/bits"
 	"reflect"
 	"strconv"
@@ -39,7 +40,6 @@ import (
 	"time"
 
 	"gvisor.dev/gvisor/pkg/sync"
-	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
@@ -113,6 +113,7 @@ var (
 	ErrNotPermitted              = &Error{msg: "operation not permitted"}
 	ErrAddressFamilyNotSupported = &Error{msg: "address family not supported by protocol"}
 	ErrMalformedHeader           = &Error{msg: "header is malformed"}
+	ErrBadBuffer                 = &Error{msg: "bad buffer"}
 )
 
 var messageToError map[string]*Error
@@ -162,6 +163,7 @@ func StringToError(s string) *Error {
 			ErrNotPermitted,
 			ErrAddressFamilyNotSupported,
 			ErrMalformedHeader,
+			ErrBadBuffer,
 		}
 
 		messageToError = make(map[string]*Error)
@@ -496,6 +498,21 @@ func (s SlicePayload) Payload(size int) ([]byte, *Error) {
 	return s[:size], nil
 }
 
+var _ io.Writer = (*SliceWriter)(nil)
+
+// SliceWriter implements io.Writer for slices.
+type SliceWriter []byte
+
+// Write implements io.Writer.Write.
+func (s *SliceWriter) Write(b []byte) (int, error) {
+	n := copy(*s, b)
+	*s = (*s)[n:]
+	if n < len(b) {
+		return n, io.ErrShortWrite
+	}
+	return n, nil
+}
+
 // A ControlMessages contains socket control messages for IP sockets.
 //
 // +stateify savable
@@ -552,6 +569,40 @@ type PacketOwner interface {
 	GID() uint32
 }
 
+// ReadOptions contains options for Endpoint.Read.
+type ReadOptions struct {
+	// Peek indicates whether this read is a peek.
+	Peek bool
+
+	// NeedRemoteAddr indicates whether to return the remote address, if
+	// supported.
+	NeedRemoteAddr bool
+
+	// NeedLinkPacketInfo indicates whether to return the link-layer information,
+	// if supported.
+	NeedLinkPacketInfo bool
+}
+
+// ReadResult represents result for a successful Endpoint.Read.
+type ReadResult struct {
+	// Count is the number of bytes received and written to the buffer.
+	Count int
+
+	// Total is the number of bytes of the received packet. This can be used to
+	// determine whether the read is truncated.
+	Total int
+
+	// ControlMessages is the control messages received.
+	ControlMessages ControlMessages
+
+	// RemoteAddr is the remote address if ReadOptions.NeedAddr is true.
+	RemoteAddr FullAddress
+
+	// LinkPacketInfo is the link-layer information of the received packet if
+	// ReadOptions.NeedLinkPacketInfo is true.
+	LinkPacketInfo LinkPacketInfo
+}
+
 // Endpoint is the interface implemented by transport protocols (e.g., tcp, udp)
 // that exposes functionality like read, write, connect, etc. to users of the
 // networking stack.
@@ -566,11 +617,15 @@ type Endpoint interface {
 	// Abort is best effort; implementing Abort with Close is acceptable.
 	Abort()
 
-	// Read reads data from the endpoint and optionally returns the sender.
+	// Read reads data from the endpoint and optionally writes to dst.
+	//
+	// This method does not block if there is no data pending; in this case,
+	// ErrWouldBlock is returned.
 	//
-	// This method does not block if there is no data pending. It will also
-	// either return an error or data, never both.
-	Read(*FullAddress) (buffer.View, ControlMessages, *Error)
+	// If non-zero number of bytes are successfully read and written to dst, err
+	// must be nil. Otherwise, if dst failed to write anything, ErrBadBuffer
+	// should be returned.
+	Read(dst io.Writer, count int, opts ReadOptions) (res ReadResult, err *Error)
 
 	// Write writes data to the endpoint's peer. This method does not block if
 	// the data cannot be written.
@@ -592,11 +647,6 @@ type Endpoint interface {
 	// not). The channel is only non-nil in this case.
 	Write(Payloader, WriteOptions) (int64, <-chan struct{}, *Error)
 
-	// Peek reads data without consuming it from the endpoint.
-	//
-	// This method does not block if there is no data pending.
-	Peek([][]byte) (int64, *Error)
-
 	// Connect connects the endpoint to its peer. Specifying a NIC is
 	// optional.
 	//
@@ -703,17 +753,6 @@ type LinkPacketInfo struct {
 	PktType PacketType
 }
 
-// PacketEndpoint are additional methods that are only implemented by Packet
-// endpoints.
-type PacketEndpoint interface {
-	// ReadPacket reads a datagram/packet from the endpoint and optionally
-	// returns the sender and additional LinkPacketInfo.
-	//
-	// This method does not block if there is no data pending. It will also
-	// either return an error or data, never both.
-	ReadPacket(*FullAddress, *LinkPacketInfo) (buffer.View, ControlMessages, *Error)
-}
-
 // EndpointInfo is the interface implemented by each endpoint info struct.
 type EndpointInfo interface {
 	// IsEndpointInfo is an empty method to implement the tcpip.EndpointInfo
diff --git a/pkg/tcpip/tests/integration/BUILD b/pkg/tcpip/tests/integration/BUILD
index bb3b2ed0d..ca1e88e99 100644
--- a/pkg/tcpip/tests/integration/BUILD
+++ b/pkg/tcpip/tests/integration/BUILD
@@ -15,6 +15,7 @@ go_test(
     deps = [
         "//pkg/tcpip",
         "//pkg/tcpip/buffer",
+        "//pkg/tcpip/checker",
         "//pkg/tcpip/header",
         "//pkg/tcpip/link/channel",
         "//pkg/tcpip/link/ethernet",
diff --git a/pkg/tcpip/tests/integration/forward_test.go b/pkg/tcpip/tests/integration/forward_test.go
index 907565ac4..60054d6ef 100644
--- a/pkg/tcpip/tests/integration/forward_test.go
+++ b/pkg/tcpip/tests/integration/forward_test.go
@@ -15,12 +15,13 @@
 package integration_test
 
 import (
+	"bytes"
 	"net"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
-	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/checker"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/ethernet"
 	"gvisor.dev/gvisor/pkg/tcpip/link/nested"
@@ -382,24 +383,33 @@ func TestForwarding(t *testing.T) {
 
 				// Wait for the endpoint to be readable.
 				<-ch
-				var addr tcpip.FullAddress
-				v, _, err := ep.Read(&addr)
+				var buf bytes.Buffer
+				opts := tcpip.ReadOptions{NeedRemoteAddr: true}
+				res, err := ep.Read(&buf, len(data), opts)
 				if err != nil {
-					t.Fatalf("ep.Read(_): %s", err)
+					t.Fatalf("ep.Read(_, %d, %#v): %s", len(data), opts, err)
 				}
 
-				if diff := cmp.Diff(v, buffer.View(data)); diff != "" {
-					t.Errorf("received data mismatch (-want +got):\n%s", diff)
+				if diff := cmp.Diff(tcpip.ReadResult{
+					Count:      len(data),
+					Total:      len(data),
+					RemoteAddr: tcpip.FullAddress{Addr: expectedFrom},
+				}, res, checker.IgnoreCmpPath(
+					"ControlMessages",
+					"RemoteAddr.NIC",
+					"RemoteAddr.Port",
+				)); diff != "" {
+					t.Errorf("ep.Read: unexpected result (-want +got):\n%s", diff)
 				}
-				if addr.Addr != expectedFrom {
-					t.Errorf("got addr.Addr = %s, want = %s", addr.Addr, expectedFrom)
+				if diff := cmp.Diff(buf.Bytes(), data); diff != "" {
+					t.Errorf("received data mismatch (-want +got):\n%s", diff)
 				}
 
 				if t.Failed() {
 					t.FailNow()
 				}
 
-				return addr
+				return res.RemoteAddr
 			}
 
 			addr := read(epsAndAddrs.serverReadableCH, epsAndAddrs.serverEP, data, epsAndAddrs.clientAddr)
diff --git a/pkg/tcpip/tests/integration/link_resolution_test.go b/pkg/tcpip/tests/integration/link_resolution_test.go
index b41b72381..209da3903 100644
--- a/pkg/tcpip/tests/integration/link_resolution_test.go
+++ b/pkg/tcpip/tests/integration/link_resolution_test.go
@@ -15,12 +15,13 @@
 package integration_test
 
 import (
+	"bytes"
 	"net"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
-	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/checker"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/pipe"
 	"gvisor.dev/gvisor/pkg/tcpip/network/arp"
@@ -86,21 +87,21 @@ func TestPing(t *testing.T) {
 		transProto tcpip.TransportProtocolNumber
 		netProto   tcpip.NetworkProtocolNumber
 		remoteAddr tcpip.Address
-		icmpBuf    func(*testing.T) buffer.View
+		icmpBuf    func(*testing.T) []byte
 	}{
 		{
 			name:       "IPv4 Ping",
 			transProto: icmp.ProtocolNumber4,
 			netProto:   ipv4.ProtocolNumber,
 			remoteAddr: ipv4Addr2.AddressWithPrefix.Address,
-			icmpBuf: func(t *testing.T) buffer.View {
+			icmpBuf: func(t *testing.T) []byte {
 				data := [8]byte{1, 2, 3, 4, 5, 6, 7, 8}
 				hdr := header.ICMPv4(make([]byte, header.ICMPv4MinimumSize+len(data)))
 				hdr.SetType(header.ICMPv4Echo)
 				if n := copy(hdr.Payload(), data[:]); n != len(data) {
 					t.Fatalf("copied %d bytes but expected to copy %d bytes", n, len(data))
 				}
-				return buffer.View(hdr)
+				return hdr
 			},
 		},
 		{
@@ -108,14 +109,14 @@ func TestPing(t *testing.T) {
 			transProto: icmp.ProtocolNumber6,
 			netProto:   ipv6.ProtocolNumber,
 			remoteAddr: ipv6Addr2.AddressWithPrefix.Address,
-			icmpBuf: func(t *testing.T) buffer.View {
+			icmpBuf: func(t *testing.T) []byte {
 				data := [8]byte{1, 2, 3, 4, 5, 6, 7, 8}
 				hdr := header.ICMPv6(make([]byte, header.ICMPv6MinimumSize+len(data)))
 				hdr.SetType(header.ICMPv6EchoRequest)
 				if n := copy(hdr.Payload(), data[:]); n != len(data) {
 					t.Fatalf("copied %d bytes but expected to copy %d bytes", n, len(data))
 				}
-				return buffer.View(hdr)
+				return hdr
 			},
 		},
 	}
@@ -200,16 +201,25 @@ func TestPing(t *testing.T) {
 			// Wait for the endpoint to be readable.
 			<-waiterCH
 
-			var addr tcpip.FullAddress
-			v, _, err := ep.Read(&addr)
+			var buf bytes.Buffer
+			opts := tcpip.ReadOptions{NeedRemoteAddr: true}
+			res, err := ep.Read(&buf, len(icmpBuf), opts)
 			if err != nil {
-				t.Fatalf("ep.Read(_): %s", err)
+				t.Fatalf("ep.Read(_, %d, %#v): %s", len(icmpBuf), opts, err)
 			}
-			if diff := cmp.Diff(v[icmpDataOffset:], icmpBuf[icmpDataOffset:]); diff != "" {
-				t.Errorf("received data mismatch (-want +got):\n%s", diff)
+			if diff := cmp.Diff(tcpip.ReadResult{
+				Count:      buf.Len(),
+				Total:      buf.Len(),
+				RemoteAddr: tcpip.FullAddress{Addr: test.remoteAddr},
+			}, res, checker.IgnoreCmpPath(
+				"ControlMessages",
+				"RemoteAddr.NIC",
+				"RemoteAddr.Port",
+			)); diff != "" {
+				t.Errorf("ep.Read: unexpected result (-want +got):\n%s", diff)
 			}
-			if addr.Addr != test.remoteAddr {
-				t.Errorf("got addr.Addr = %s, want = %s", addr.Addr, test.remoteAddr)
+			if diff := cmp.Diff(buf.Bytes()[icmpDataOffset:], icmpBuf[icmpDataOffset:]); diff != "" {
+				t.Errorf("received data mismatch (-want +got):\n%s", diff)
 			}
 		})
 	}
diff --git a/pkg/tcpip/tests/integration/loopback_test.go b/pkg/tcpip/tests/integration/loopback_test.go
index baaa741cd..cf9e86c3c 100644
--- a/pkg/tcpip/tests/integration/loopback_test.go
+++ b/pkg/tcpip/tests/integration/loopback_test.go
@@ -15,12 +15,14 @@
 package integration_test
 
 import (
+	"bytes"
 	"testing"
 	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/checker"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/loopback"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
@@ -238,21 +240,28 @@ func TestLoopbackAcceptAllInSubnetUDP(t *testing.T) {
 				t.Fatalf("got sep.Write(_, _) = (%d, _, nil), want = (%d, _, nil)", n, want)
 			}
 
-			var addr tcpip.FullAddress
-			if gotPayload, _, err := rep.Read(&addr); test.expectRx {
+			var buf bytes.Buffer
+			opts := tcpip.ReadOptions{NeedRemoteAddr: true}
+			if res, err := rep.Read(&buf, len(data), opts); test.expectRx {
 				if err != nil {
-					t.Fatalf("reep.Read(_): %s", err)
-				}
-				if diff := cmp.Diff(buffer.View(data), gotPayload); diff != "" {
-					t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff)
+					t.Fatalf("rep.Read(_, %d, %#v): %s", len(data), opts, err)
 				}
-				if addr.Addr != test.addAddress.AddressWithPrefix.Address {
-					t.Errorf("got addr.Addr = %s, want = %s", addr.Addr, test.addAddress.AddressWithPrefix.Address)
+				if diff := cmp.Diff(tcpip.ReadResult{
+					Count: buf.Len(),
+					Total: buf.Len(),
+					RemoteAddr: tcpip.FullAddress{
+						Addr: test.addAddress.AddressWithPrefix.Address,
+					},
+				}, res,
+					checker.IgnoreCmpPath("ControlMessages", "RemoteAddr.NIC", "RemoteAddr.Port"),
+				); diff != "" {
+					t.Errorf("rep.Read: unexpected result (-want +got):\n%s", diff)
 				}
-			} else {
-				if err != tcpip.ErrWouldBlock {
-					t.Fatalf("got rep.Read(nil) = (%x, _, %s), want = (_, _, %s)", gotPayload, err, tcpip.ErrWouldBlock)
+				if diff := cmp.Diff(data, buf.Bytes()); diff != "" {
+					t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff)
 				}
+			} else if err != tcpip.ErrWouldBlock {
+				t.Fatalf("got rep.Read = (%v, %s) [with data %x], want = (_, %s)", res, err, buf.Bytes(), tcpip.ErrWouldBlock)
 			}
 		})
 	}
diff --git a/pkg/tcpip/tests/integration/multicast_broadcast_test.go b/pkg/tcpip/tests/integration/multicast_broadcast_test.go
index 20f8a7e6c..fae6c256a 100644
--- a/pkg/tcpip/tests/integration/multicast_broadcast_test.go
+++ b/pkg/tcpip/tests/integration/multicast_broadcast_test.go
@@ -15,12 +15,14 @@
 package integration_test
 
 import (
+	"bytes"
 	"net"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/checker"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/link/loopback"
@@ -462,17 +464,23 @@ func TestIncomingMulticastAndBroadcast(t *testing.T) {
 			}
 
 			test.rxUDP(e, test.remoteAddr, test.dstAddr, data)
-			if gotPayload, _, err := ep.Read(nil); test.expectRx {
+			var buf bytes.Buffer
+			var opts tcpip.ReadOptions
+			if res, err := ep.Read(&buf, len(data), opts); test.expectRx {
 				if err != nil {
-					t.Fatalf("Read(nil): %s", err)
+					t.Fatalf("ep.Read(_, %d, %#v): %s", len(data), opts, err)
 				}
-				if diff := cmp.Diff(buffer.View(data), gotPayload); diff != "" {
-					t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff)
+				if diff := cmp.Diff(tcpip.ReadResult{
+					Count: buf.Len(),
+					Total: buf.Len(),
+				}, res, checker.IgnoreCmpPath("ControlMessages")); diff != "" {
+					t.Errorf("ep.Read: unexpected result (-want +got):\n%s", diff)
 				}
-			} else {
-				if err != tcpip.ErrWouldBlock {
-					t.Fatalf("got Read(nil) = (%x, _, %s), want = (_, _, %s)", gotPayload, err, tcpip.ErrWouldBlock)
+				if diff := cmp.Diff(data, buf.Bytes()); diff != "" {
+					t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff)
 				}
+			} else if err != tcpip.ErrWouldBlock {
+				t.Fatalf("got Read = (%v, %s) [with data %x], want = (_, %s)", res, err, buf.Bytes(), tcpip.ErrWouldBlock)
 			}
 		})
 	}
@@ -589,9 +597,19 @@ func TestReuseAddrAndBroadcast(t *testing.T) {
 					// Wait for the endpoint to become readable.
 					<-rep.ch
 
-					if gotPayload, _, err := rep.ep.Read(nil); err != nil {
-						t.Errorf("(eps[%d] write) eps[%d].Read(nil): %s", i, j, err)
-					} else if diff := cmp.Diff(buffer.View(data), gotPayload); diff != "" {
+					var buf bytes.Buffer
+					result, err := rep.ep.Read(&buf, len(data), tcpip.ReadOptions{})
+					if err != nil {
+						t.Errorf("(eps[%d] write) eps[%d].Read: %s", i, j, err)
+						continue
+					}
+					if diff := cmp.Diff(tcpip.ReadResult{
+						Count: buf.Len(),
+						Total: buf.Len(),
+					}, result, checker.IgnoreCmpPath("ControlMessages")); diff != "" {
+						t.Errorf("(eps[%d] write) eps[%d].Read: unexpected result (-want +got):\n%s", i, j, diff)
+					}
+					if diff := cmp.Diff([]byte(data), buf.Bytes()); diff != "" {
 						t.Errorf("(eps[%d] write) got UDP payload from eps[%d] mismatch (-want +got):\n%s", i, j, diff)
 					}
 				}
@@ -719,10 +737,20 @@ func TestUDPAddRemoveMembershipSocketOption(t *testing.T) {
 						t.Fatalf("ep.SetSockOpt(&%#v): %s", addOpt, err)
 					}
 					test.rxUDP(e, test.remoteAddr, test.multicastAddr, data)
-					if gotPayload, _, err := ep.Read(nil); err != nil {
-						t.Fatalf("ep.Read(nil): %s", err)
-					} else if diff := cmp.Diff(buffer.View(data), gotPayload); diff != "" {
-						t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff)
+					var buf bytes.Buffer
+					result, err := ep.Read(&buf, len(data), tcpip.ReadOptions{})
+					if err != nil {
+						t.Fatalf("ep.Read: %s", err)
+					} else {
+						if diff := cmp.Diff(tcpip.ReadResult{
+							Count: buf.Len(),
+							Total: buf.Len(),
+						}, result, checker.IgnoreCmpPath("ControlMessages")); diff != "" {
+							t.Errorf("ep.Read: unexpected result (-want +got):\n%s", diff)
+						}
+						if diff := cmp.Diff(data, buf.Bytes()); diff != "" {
+							t.Errorf("got UDP payload mismatch (-want +got):\n%s", diff)
+						}
 					}
 
 					// We should not receive UDP packets to the group once we leave
@@ -731,8 +759,8 @@ func TestUDPAddRemoveMembershipSocketOption(t *testing.T) {
 					if err := ep.SetSockOpt(&removeOpt); err != nil {
 						t.Fatalf("ep.SetSockOpt(&%#v): %s", removeOpt, err)
 					}
-					if gotPayload, _, err := ep.Read(nil); err != tcpip.ErrWouldBlock {
-						t.Fatalf("got ep.Read(nil) = (%x, _, %s), want = (nil, _, %s)", gotPayload, err, tcpip.ErrWouldBlock)
+					if _, err := ep.Read(&buf, 1, tcpip.ReadOptions{}); err != tcpip.ErrWouldBlock {
+						t.Fatalf("got ep.Read = (_, %s), want = (_, %s)", err, tcpip.ErrWouldBlock)
 					}
 				})
 			}
diff --git a/pkg/tcpip/tests/integration/route_test.go b/pkg/tcpip/tests/integration/route_test.go
index 02fc47015..52cf89b54 100644
--- a/pkg/tcpip/tests/integration/route_test.go
+++ b/pkg/tcpip/tests/integration/route_test.go
@@ -15,11 +15,14 @@
 package integration_test
 
 import (
+	"bytes"
+	"math"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/checker"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/link/loopback"
@@ -203,16 +206,25 @@ func TestLocalPing(t *testing.T) {
 			// Wait for the endpoint to become readable.
 			<-ch
 
-			var addr tcpip.FullAddress
-			v, _, err := ep.Read(&addr)
+			var buf bytes.Buffer
+			opts := tcpip.ReadOptions{NeedRemoteAddr: true}
+			res, err := ep.Read(&buf, math.MaxUint16, opts)
 			if err != nil {
-				t.Fatalf("ep.Read(_): %s", err)
+				t.Fatalf("ep.Read(_, %d, %#v): %s", math.MaxUint16, opts, err)
 			}
-			if diff := cmp.Diff(v[icmpDataOffset:], buffer.View(payload[icmpDataOffset:])); diff != "" {
-				t.Errorf("received data mismatch (-want +got):\n%s", diff)
+			if diff := cmp.Diff(tcpip.ReadResult{
+				Count:      buf.Len(),
+				Total:      buf.Len(),
+				RemoteAddr: tcpip.FullAddress{Addr: test.localAddr},
+			}, res, checker.IgnoreCmpPath(
+				"ControlMessages",
+				"RemoteAddr.NIC",
+				"RemoteAddr.Port",
+			)); diff != "" {
+				t.Errorf("ep.Read: unexpected result (-want +got):\n%s", diff)
 			}
-			if addr.Addr != test.localAddr {
-				t.Errorf("got addr.Addr = %s, want = %s", addr.Addr, test.localAddr)
+			if diff := cmp.Diff(buf.Bytes()[icmpDataOffset:], []byte(payload[icmpDataOffset:])); diff != "" {
+				t.Errorf("received data mismatch (-want +got):\n%s", diff)
 			}
 
 			test.checkLinkEndpoint(t, e)
@@ -338,14 +350,27 @@ func TestLocalUDP(t *testing.T) {
 					<-serverCH
 
 					var clientAddr tcpip.FullAddress
-					if v, _, err := server.Read(&clientAddr); err != nil {
+					var readBuf bytes.Buffer
+					if read, err := server.Read(&readBuf, math.MaxUint16, tcpip.ReadOptions{NeedRemoteAddr: true}); err != nil {
 						t.Fatalf("server.Read(_): %s", err)
 					} else {
-						if diff := cmp.Diff(buffer.View(clientPayload), v); diff != "" {
-							t.Errorf("server read clientPayload mismatch (-want +got):\n%s", diff)
+						clientAddr = read.RemoteAddr
+
+						if diff := cmp.Diff(tcpip.ReadResult{
+							Count: readBuf.Len(),
+							Total: readBuf.Len(),
+							RemoteAddr: tcpip.FullAddress{
+								Addr: test.canBePrimaryAddr.AddressWithPrefix.Address,
+							},
+						}, read, checker.IgnoreCmpPath(
+							"ControlMessages",
+							"RemoteAddr.NIC",
+							"RemoteAddr.Port",
+						)); diff != "" {
+							t.Errorf("server.Read: unexpected result (-want +got):\n%s", diff)
 						}
-						if clientAddr.Addr != test.canBePrimaryAddr.AddressWithPrefix.Address {
-							t.Errorf("got clientAddr.Addr = %s, want = %s", clientAddr.Addr, test.canBePrimaryAddr.AddressWithPrefix.Address)
+						if diff := cmp.Diff(buffer.View(clientPayload), buffer.View(readBuf.Bytes())); diff != "" {
+							t.Errorf("server read clientPayload mismatch (-want +got):\n%s", diff)
 						}
 						if t.Failed() {
 							t.FailNow()
@@ -367,15 +392,23 @@ func TestLocalUDP(t *testing.T) {
 					// Wait for the client endpoint to become readable.
 					<-clientCH
 
-					var gotServerAddr tcpip.FullAddress
-					if v, _, err := client.Read(&gotServerAddr); err != nil {
+					readBuf.Reset()
+					if read, err := client.Read(&readBuf, math.MaxUint16, tcpip.ReadOptions{NeedRemoteAddr: true}); err != nil {
 						t.Fatalf("client.Read(_): %s", err)
 					} else {
-						if diff := cmp.Diff(buffer.View(serverPayload), v); diff != "" {
-							t.Errorf("client read serverPayload mismatch (-want +got):\n%s", diff)
+						if diff := cmp.Diff(tcpip.ReadResult{
+							Count:      readBuf.Len(),
+							Total:      readBuf.Len(),
+							RemoteAddr: tcpip.FullAddress{Addr: serverAddr.Addr},
+						}, read, checker.IgnoreCmpPath(
+							"ControlMessages",
+							"RemoteAddr.NIC",
+							"RemoteAddr.Port",
+						)); diff != "" {
+							t.Errorf("client.Read: unexpected result (-want +got):\n%s", diff)
 						}
-						if gotServerAddr.Addr != serverAddr.Addr {
-							t.Errorf("got gotServerAddr.Addr = %s, want = %s", gotServerAddr.Addr, serverAddr.Addr)
+						if diff := cmp.Diff(buffer.View(serverPayload), buffer.View(readBuf.Bytes())); diff != "" {
+							t.Errorf("client read serverPayload mismatch (-want +got):\n%s", diff)
 						}
 						if t.Failed() {
 							t.FailNow()
diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index d1e4a7cb7..2eb4457df 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -15,6 +15,8 @@
 package icmp
 
 import (
+	"io"
+
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
@@ -151,9 +153,8 @@ func (e *endpoint) SetOwner(owner tcpip.PacketOwner) {
 	e.owner = owner
 }
 
-// Read reads data from the endpoint. This method does not block if
-// there is no data pending.
-func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+// Read implements tcpip.Endpoint.Read.
+func (e *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
 	e.rcvMu.Lock()
 
 	if e.rcvList.Empty() {
@@ -163,20 +164,34 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 			err = tcpip.ErrClosedForReceive
 		}
 		e.rcvMu.Unlock()
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	p := e.rcvList.Front()
-	e.rcvList.Remove(p)
-	e.rcvBufSize -= p.data.Size()
+	if !opts.Peek {
+		e.rcvList.Remove(p)
+		e.rcvBufSize -= p.data.Size()
+	}
 
 	e.rcvMu.Unlock()
 
-	if addr != nil {
-		*addr = p.senderAddress
+	res := tcpip.ReadResult{
+		Total: p.data.Size(),
+		ControlMessages: tcpip.ControlMessages{
+			HasTimestamp: true,
+			Timestamp:    p.timestamp,
+		},
+	}
+	if opts.NeedRemoteAddr {
+		res.RemoteAddr = p.senderAddress
 	}
 
-	return p.data.ToView(), tcpip.ControlMessages{HasTimestamp: true, Timestamp: p.timestamp}, nil
+	n, err := p.data.ReadTo(dst, count, opts.Peek)
+	if n == 0 && err != nil {
+		return res, tcpip.ErrBadBuffer
+	}
+	res.Count = n
+	return res, nil
 }
 
 // prepareForWrite prepares the endpoint for sending data. In particular, it
@@ -329,11 +344,6 @@ func (e *endpoint) write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-c
 	return int64(len(v)), nil, nil
 }
 
-// Peek only returns data from a single datagram, so do nothing here.
-func (e *endpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // SetSockOpt sets a socket option.
 func (e *endpoint) SetSockOpt(opt tcpip.SettableSocketOption) *tcpip.Error {
 	return nil
diff --git a/pkg/tcpip/transport/packet/endpoint.go b/pkg/tcpip/transport/packet/endpoint.go
index e5e247342..3ab060751 100644
--- a/pkg/tcpip/transport/packet/endpoint.go
+++ b/pkg/tcpip/transport/packet/endpoint.go
@@ -26,6 +26,7 @@ package packet
 
 import (
 	"fmt"
+	"io"
 
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -160,8 +161,8 @@ func (ep *endpoint) Close() {
 // ModerateRecvBuf implements tcpip.Endpoint.ModerateRecvBuf.
 func (ep *endpoint) ModerateRecvBuf(copied int) {}
 
-// Read implements tcpip.PacketEndpoint.ReadPacket.
-func (ep *endpoint) ReadPacket(addr *tcpip.FullAddress, info *tcpip.LinkPacketInfo) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+// Read implements tcpip.Endpoint.Read.
+func (ep *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
 	ep.rcvMu.Lock()
 
 	// If there's no data to read, return that read would block or that the
@@ -173,29 +174,37 @@ func (ep *endpoint) ReadPacket(addr *tcpip.FullAddress, info *tcpip.LinkPacketIn
 			err = tcpip.ErrClosedForReceive
 		}
 		ep.rcvMu.Unlock()
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	packet := ep.rcvList.Front()
-	ep.rcvList.Remove(packet)
-	ep.rcvBufSize -= packet.data.Size()
+	if !opts.Peek {
+		ep.rcvList.Remove(packet)
+		ep.rcvBufSize -= packet.data.Size()
+	}
 
 	ep.rcvMu.Unlock()
 
-	if addr != nil {
-		*addr = packet.senderAddr
+	res := tcpip.ReadResult{
+		Total: packet.data.Size(),
+		ControlMessages: tcpip.ControlMessages{
+			HasTimestamp: true,
+			Timestamp:    packet.timestampNS,
+		},
 	}
-
-	if info != nil {
-		*info = packet.packetInfo
+	if opts.NeedRemoteAddr {
+		res.RemoteAddr = packet.senderAddr
+	}
+	if opts.NeedLinkPacketInfo {
+		res.LinkPacketInfo = packet.packetInfo
 	}
 
-	return packet.data.ToView(), tcpip.ControlMessages{HasTimestamp: true, Timestamp: packet.timestampNS}, nil
-}
-
-// Read implements tcpip.Endpoint.Read.
-func (ep *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
-	return ep.ReadPacket(addr, nil)
+	n, err := packet.data.ReadTo(dst, count, opts.Peek)
+	if n == 0 && err != nil {
+		return res, tcpip.ErrBadBuffer
+	}
+	res.Count = n
+	return res, nil
 }
 
 func (*endpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-chan struct{}, *tcpip.Error) {
@@ -203,11 +212,6 @@ func (*endpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-cha
 	return 0, nil, tcpip.ErrInvalidOptionValue
 }
 
-// Peek implements tcpip.Endpoint.Peek.
-func (*endpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // Disconnect implements tcpip.Endpoint.Disconnect. Packet sockets cannot be
 // disconnected, and this function always returns tpcip.ErrNotSupported.
 func (*endpoint) Disconnect() *tcpip.Error {
diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
index 7befcfc9b..dd260535f 100644
--- a/pkg/tcpip/transport/raw/endpoint.go
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -27,6 +27,7 @@ package raw
 
 import (
 	"fmt"
+	"io"
 
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -190,7 +191,7 @@ func (e *endpoint) SetOwner(owner tcpip.PacketOwner) {
 }
 
 // Read implements tcpip.Endpoint.Read.
-func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+func (e *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
 	e.rcvMu.Lock()
 
 	// If there's no data to read, return that read would block or that the
@@ -202,20 +203,34 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 			err = tcpip.ErrClosedForReceive
 		}
 		e.rcvMu.Unlock()
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	pkt := e.rcvList.Front()
-	e.rcvList.Remove(pkt)
-	e.rcvBufSize -= pkt.data.Size()
+	if !opts.Peek {
+		e.rcvList.Remove(pkt)
+		e.rcvBufSize -= pkt.data.Size()
+	}
 
 	e.rcvMu.Unlock()
 
-	if addr != nil {
-		*addr = pkt.senderAddr
+	res := tcpip.ReadResult{
+		Total: pkt.data.Size(),
+		ControlMessages: tcpip.ControlMessages{
+			HasTimestamp: true,
+			Timestamp:    pkt.timestampNS,
+		},
+	}
+	if opts.NeedRemoteAddr {
+		res.RemoteAddr = pkt.senderAddr
 	}
 
-	return pkt.data.ToView(), tcpip.ControlMessages{HasTimestamp: true, Timestamp: pkt.timestampNS}, nil
+	n, err := pkt.data.ReadTo(dst, count, opts.Peek)
+	if n == 0 && err != nil {
+		return res, tcpip.ErrBadBuffer
+	}
+	res.Count = n
+	return res, nil
 }
 
 // Write implements tcpip.Endpoint.Write.
@@ -363,11 +378,6 @@ func (e *endpoint) finishWrite(payloadBytes []byte, route *stack.Route) (int64,
 	return int64(len(payloadBytes)), nil, nil
 }
 
-// Peek implements tcpip.Endpoint.Peek.
-func (e *endpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // Disconnect implements tcpip.Endpoint.Disconnect.
 func (*endpoint) Disconnect() *tcpip.Error {
 	return tcpip.ErrNotSupported
diff --git a/pkg/tcpip/transport/tcp/BUILD b/pkg/tcpip/transport/tcp/BUILD
index cf232b508..7e81203ba 100644
--- a/pkg/tcpip/transport/tcp/BUILD
+++ b/pkg/tcpip/transport/tcp/BUILD
@@ -112,6 +112,7 @@ go_test(
         "//pkg/tcpip/transport/tcp/testing/context",
         "//pkg/test/testutil",
         "//pkg/waiter",
+        "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
 
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 6e3c8860e..8f3981075 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -17,6 +17,7 @@ package tcp
 import (
 	"encoding/binary"
 	"fmt"
+	"io"
 	"math"
 	"runtime"
 	"strings"
@@ -27,7 +28,6 @@ import (
 	"gvisor.dev/gvisor/pkg/sleep"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
-	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/hash/jenkins"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/ports"
@@ -393,15 +393,28 @@ type endpoint struct {
 	lastErrorMu sync.Mutex   `state:"nosave"`
 	lastError   *tcpip.Error `state:".(string)"`
 
-	// The following fields are used to manage the receive queue. The
-	// protocol goroutine adds ready-for-delivery segments to rcvList,
-	// which are returned by Read() calls to users.
+	// rcvReadMu synchronizes calls to Read.
 	//
-	// Once the peer has closed its send side, rcvClosed is set to true
-	// to indicate to users that no more data is coming.
+	// mu and rcvListMu are temporarily released during data copying. rcvReadMu
+	// must be held during each read to ensure atomicity, so that multiple reads
+	// do not interleave.
+	//
+	// rcvReadMu should be held before holding mu.
+	rcvReadMu sync.Mutex `state:"nosave"`
+
+	// rcvListMu synchronizes access to rcvList.
 	//
 	// rcvListMu can be taken after the endpoint mu below.
-	rcvListMu sync.Mutex  `state:"nosave"`
+	rcvListMu sync.Mutex `state:"nosave"`
+
+	// rcvList is the queue for ready-for-delivery segments.
+	//
+	// rcvReadMu, mu and rcvListMu must be held, in the stated order, to read data
+	// and removing segments from list. A range of segment can be determined, then
+	// temporarily release mu and rcvListMu while processing the segment range.
+	// This allows new segments to be appended to the list while processing.
+	//
+	// rcvListMu must be held to append segments to list.
 	rcvList   segmentList `state:"wait"`
 	rcvClosed bool
 	// rcvBufSize is the total size of the receive buffer.
@@ -1309,8 +1322,69 @@ func (e *endpoint) UpdateLastError(err *tcpip.Error) {
 	e.UnlockUser()
 }
 
-// Read reads data from the endpoint.
-func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+// Read implements tcpip.Endpoint.Read.
+func (e *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
+	e.rcvReadMu.Lock()
+	defer e.rcvReadMu.Unlock()
+
+	// N.B. Here we get a range of segments to be processed. It is safe to not
+	// hold rcvListMu when processing, since we hold rcvReadMu to ensure only we
+	// can remove segments from the list through commitRead().
+	first, last, serr := e.startRead()
+	if serr != nil {
+		if serr == tcpip.ErrClosedForReceive {
+			e.stats.ReadErrors.ReadClosed.Increment()
+		}
+		return tcpip.ReadResult{}, serr
+	}
+
+	var err error
+	done := 0
+	s := first
+	for s != nil && done < count {
+		var n int
+		n, err = s.data.ReadTo(dst, count-done, opts.Peek)
+		// Book keeping first then error handling.
+
+		done += n
+
+		if opts.Peek {
+			// For peek, we use the (first, last) range of segment returned from
+			// startRead. We don't consume the receive buffer, so commitRead should
+			// not be called.
+			//
+			// N.B. It is important to use `last` to determine the last segment, since
+			// appending can happen while we process, and will lead to data race.
+			if s == last {
+				break
+			}
+			s = s.Next()
+		} else {
+			// N.B. commitRead() conveniently returns the next segment to read, after
+			// removing the data/segment that is read.
+			s = e.commitRead(n)
+		}
+
+		if err != nil {
+			break
+		}
+	}
+
+	// If something is read, we must report it. Report error when nothing is read.
+	if done == 0 && err != nil {
+		return tcpip.ReadResult{}, tcpip.ErrBadBuffer
+	}
+	return tcpip.ReadResult{
+		Count: done,
+		Total: done,
+	}, nil
+}
+
+// startRead checks that endpoint is in a readable state, and return the
+// inclusive range of segments that can be read.
+//
+// Precondition: e.rcvReadMu must be held.
+func (e *endpoint) startRead() (first, last *segment, err *tcpip.Error) {
 	e.LockUser()
 	defer e.UnlockUser()
 
@@ -1319,7 +1393,7 @@ func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages,
 	// on a receive. It can expect to read any data after the handshake
 	// is complete. RFC793, section 3.9, p58.
 	if e.EndpointState() == StateSynSent {
-		return buffer.View{}, tcpip.ControlMessages{}, tcpip.ErrWouldBlock
+		return nil, nil, tcpip.ErrWouldBlock
 	}
 
 	// The endpoint can be read if it's connected, or if it's already closed
@@ -1327,61 +1401,69 @@ func (e *endpoint) Read(*tcpip.FullAddress) (buffer.View, tcpip.ControlMessages,
 	// would cause the state to become StateError so we should allow the
 	// reads to proceed before returning a ECONNRESET.
 	e.rcvListMu.Lock()
+	defer e.rcvListMu.Unlock()
+
 	bufUsed := e.rcvBufUsed
 	if s := e.EndpointState(); !s.connected() && s != StateClose && bufUsed == 0 {
-		e.rcvListMu.Unlock()
 		if s == StateError {
 			if err := e.hardErrorLocked(); err != nil {
-				return buffer.View{}, tcpip.ControlMessages{}, err
+				return nil, nil, err
 			}
-			return buffer.View{}, tcpip.ControlMessages{}, tcpip.ErrClosedForReceive
+			return nil, nil, tcpip.ErrClosedForReceive
 		}
 		e.stats.ReadErrors.NotConnected.Increment()
-		return buffer.View{}, tcpip.ControlMessages{}, tcpip.ErrNotConnected
+		return nil, nil, tcpip.ErrNotConnected
 	}
 
-	v, err := e.readLocked()
-	e.rcvListMu.Unlock()
-
-	if err == tcpip.ErrClosedForReceive {
-		e.stats.ReadErrors.ReadClosed.Increment()
-	}
-	return v, tcpip.ControlMessages{}, err
-}
-
-func (e *endpoint) readLocked() (buffer.View, *tcpip.Error) {
 	if e.rcvBufUsed == 0 {
 		if e.rcvClosed || !e.EndpointState().connected() {
-			return buffer.View{}, tcpip.ErrClosedForReceive
+			return nil, nil, tcpip.ErrClosedForReceive
 		}
-		return buffer.View{}, tcpip.ErrWouldBlock
+		return nil, nil, tcpip.ErrWouldBlock
 	}
 
-	s := e.rcvList.Front()
-	views := s.data.Views()
-	v := views[s.viewToDeliver]
-	s.viewToDeliver++
+	return e.rcvList.Front(), e.rcvList.Back(), nil
+}
+
+// commitRead commits a read of done bytes and returns the next non-empty
+// segment to read. Data read from the segment must have also been removed from
+// the segment in order for this method to work correctly.
+//
+// It is performance critical to call commitRead frequently when servicing a big
+// Read request, so TCP can make progress timely. Right now, it is designed to
+// do this per segment read, hence this method conveniently returns the next
+// segment to read while holding the lock.
+//
+// Precondition: e.rcvReadMu must be held.
+func (e *endpoint) commitRead(done int) *segment {
+	e.LockUser()
+	defer e.UnlockUser()
+	e.rcvListMu.Lock()
+	defer e.rcvListMu.Unlock()
 
-	var delta int
-	if s.viewToDeliver >= len(views) {
+	memDelta := 0
+	s := e.rcvList.Front()
+	for s != nil && s.data.Size() == 0 {
 		e.rcvList.Remove(s)
-		// We only free up receive buffer space when the segment is released as the
-		// segment is still holding on to the views even though some views have been
-		// read out to the user.
-		delta = s.segMemSize()
+		// Memory is only considered released when the whole segment has been
+		// read.
+		memDelta += s.segMemSize()
 		s.decRef()
+		s = e.rcvList.Front()
 	}
+	e.rcvBufUsed -= done
 
-	e.rcvBufUsed -= len(v)
-	// If the window was small before this read and if the read freed up
-	// enough buffer space, to either fit an aMSS or half a receive buffer
-	// (whichever smaller), then notify the protocol goroutine to send a
-	// window update.
-	if crossed, above := e.windowCrossedACKThresholdLocked(delta); crossed && above {
-		e.notifyProtocolGoroutine(notifyNonZeroReceiveWindow)
+	if memDelta > 0 {
+		// If the window was small before this read and if the read freed up
+		// enough buffer space, to either fit an aMSS or half a receive buffer
+		// (whichever smaller), then notify the protocol goroutine to send a
+		// window update.
+		if crossed, above := e.windowCrossedACKThresholdLocked(memDelta); crossed && above {
+			e.notifyProtocolGoroutine(notifyNonZeroReceiveWindow)
+		}
 	}
 
-	return v, nil
+	return e.rcvList.Front()
 }
 
 // isEndpointWritableLocked checks if a given endpoint is writable
@@ -1499,64 +1581,6 @@ func (e *endpoint) Write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-c
 	return queueAndSend()
 }
 
-// Peek reads data without consuming it from the endpoint.
-//
-// This method does not block if there is no data pending.
-func (e *endpoint) Peek(vec [][]byte) (int64, *tcpip.Error) {
-	e.LockUser()
-	defer e.UnlockUser()
-
-	// The endpoint can be read if it's connected, or if it's already closed
-	// but has some pending unread data.
-	if s := e.EndpointState(); !s.connected() && s != StateClose {
-		if s == StateError {
-			return 0, e.hardErrorLocked()
-		}
-		e.stats.ReadErrors.InvalidEndpointState.Increment()
-		return 0, tcpip.ErrInvalidEndpointState
-	}
-
-	e.rcvListMu.Lock()
-	defer e.rcvListMu.Unlock()
-
-	if e.rcvBufUsed == 0 {
-		if e.rcvClosed || !e.EndpointState().connected() {
-			e.stats.ReadErrors.ReadClosed.Increment()
-			return 0, tcpip.ErrClosedForReceive
-		}
-		return 0, tcpip.ErrWouldBlock
-	}
-
-	// Make a copy of vec so we can modify the slide headers.
-	vec = append([][]byte(nil), vec...)
-
-	var num int64
-	for s := e.rcvList.Front(); s != nil; s = s.Next() {
-		views := s.data.Views()
-
-		for i := s.viewToDeliver; i < len(views); i++ {
-			v := views[i]
-
-			for len(v) > 0 {
-				if len(vec) == 0 {
-					return num, nil
-				}
-				if len(vec[0]) == 0 {
-					vec = vec[1:]
-					continue
-				}
-
-				n := copy(vec[0], v)
-				v = v[n:]
-				vec[0] = vec[0][n:]
-				num += int64(n)
-			}
-		}
-	}
-
-	return num, nil
-}
-
 // selectWindowLocked returns the new window without checking for shrinking or scaling
 // applied.
 // Precondition: e.mu and e.rcvListMu must be held.
diff --git a/pkg/tcpip/transport/tcp/segment.go b/pkg/tcpip/transport/tcp/segment.go
index 5ef73ec74..c5a6d2fba 100644
--- a/pkg/tcpip/transport/tcp/segment.go
+++ b/pkg/tcpip/transport/tcp/segment.go
@@ -37,7 +37,7 @@ const (
 
 // segment represents a TCP segment. It holds the payload and parsed TCP segment
 // information, and can be added to intrusive lists.
-// segment is mostly immutable, the only field allowed to change is viewToDeliver.
+// segment is mostly immutable, the only field allowed to change is data.
 //
 // +stateify savable
 type segment struct {
@@ -60,10 +60,7 @@ type segment struct {
 	hdr header.TCP
 	// views is used as buffer for data when its length is large
 	// enough to store a VectorisedView.
-	views [8]buffer.View `state:"nosave"`
-	// viewToDeliver keeps track of the next View that should be
-	// delivered by the Read endpoint.
-	viewToDeliver  int
+	views          [8]buffer.View `state:"nosave"`
 	sequenceNumber seqnum.Value
 	ackNumber      seqnum.Value
 	flags          uint8
@@ -84,6 +81,9 @@ type segment struct {
 
 	// acked indicates if the segment has already been SACKed.
 	acked bool
+
+	// dataMemSize is the memory used by data initially.
+	dataMemSize int
 }
 
 func newIncomingSegment(id stack.TransportEndpointID, pkt *stack.PacketBuffer) *segment {
@@ -100,6 +100,7 @@ func newIncomingSegment(id stack.TransportEndpointID, pkt *stack.PacketBuffer) *
 	s.data = pkt.Data.Clone(s.views[:])
 	s.hdr = header.TCP(pkt.TransportHeader().View())
 	s.rcvdTime = time.Now()
+	s.dataMemSize = s.data.Size()
 	return s
 }
 
@@ -113,6 +114,7 @@ func newOutgoingSegment(id stack.TransportEndpointID, v buffer.View) *segment {
 		s.views[0] = v
 		s.data = buffer.NewVectorisedView(len(v), s.views[:1])
 	}
+	s.dataMemSize = s.data.Size()
 	return s
 }
 
@@ -127,12 +129,12 @@ func (s *segment) clone() *segment {
 		netProto:       s.netProto,
 		nicID:          s.nicID,
 		remoteLinkAddr: s.remoteLinkAddr,
-		viewToDeliver:  s.viewToDeliver,
 		rcvdTime:       s.rcvdTime,
 		xmitTime:       s.xmitTime,
 		xmitCount:      s.xmitCount,
 		ep:             s.ep,
 		qFlags:         s.qFlags,
+		dataMemSize:    s.dataMemSize,
 	}
 	t.data = s.data.Clone(t.views[:])
 	return t
@@ -204,7 +206,7 @@ func (s *segment) payloadSize() int {
 // segMemSize is the amount of memory used to hold the segment data and
 // the associated metadata.
 func (s *segment) segMemSize() int {
-	return SegSize + s.data.Size()
+	return SegSize + s.dataMemSize
 }
 
 // parse populates the sequence & ack numbers, flags, and window fields of the
diff --git a/pkg/tcpip/transport/tcp/segment_state.go b/pkg/tcpip/transport/tcp/segment_state.go
index 7dc2741a6..7422d8c02 100644
--- a/pkg/tcpip/transport/tcp/segment_state.go
+++ b/pkg/tcpip/transport/tcp/segment_state.go
@@ -24,16 +24,11 @@ import (
 func (s *segment) saveData() buffer.VectorisedView {
 	// We cannot save s.data directly as s.data.views may alias to s.views,
 	// which is not allowed by state framework (in-struct pointer).
-	v := make([]buffer.View, len(s.data.Views()))
-	// For views already delivered, we cannot save them directly as they may
-	// have already been sliced and saved elsewhere (e.g., readViews).
-	for i := 0; i < s.viewToDeliver; i++ {
-		v[i] = append([]byte(nil), s.data.Views()[i]...)
+	vs := make([]buffer.View, len(s.data.Views()))
+	for i, v := range s.data.Views() {
+		vs[i] = v
 	}
-	for i := s.viewToDeliver; i < len(v); i++ {
-		v[i] = s.data.Views()[i]
-	}
-	return buffer.NewVectorisedView(s.data.Size(), v)
+	return buffer.NewVectorisedView(s.data.Size(), vs)
 }
 
 // loadData is invoked by stateify.
diff --git a/pkg/tcpip/transport/tcp/tcp_test.go b/pkg/tcpip/transport/tcp/tcp_test.go
index cf60d5b53..9fa4672d7 100644
--- a/pkg/tcpip/transport/tcp/tcp_test.go
+++ b/pkg/tcpip/transport/tcp/tcp_test.go
@@ -17,10 +17,12 @@ package tcp_test
 import (
 	"bytes"
 	"fmt"
+	"io/ioutil"
 	"math"
 	"testing"
 	"time"
 
+	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/rand"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -40,6 +42,64 @@ import (
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
+// endpointTester provides helper functions to test a tcpip.Endpoint.
+type endpointTester struct {
+	ep tcpip.Endpoint
+}
+
+// CheckReadError issues a read to the endpoint and checking for an error.
+func (e *endpointTester) CheckReadError(t *testing.T, want *tcpip.Error) {
+	t.Helper()
+	res, got := e.ep.Read(ioutil.Discard, 1, tcpip.ReadOptions{})
+	if got != want {
+		t.Fatalf("ep.Read = %s, want %s", got, want)
+	}
+	if diff := cmp.Diff(tcpip.ReadResult{}, res); diff != "" {
+		t.Errorf("ep.Read: unexpected non-zero result (-want +got):\n%s", diff)
+	}
+}
+
+// CheckRead issues a read to the endpoint and checking for a success, returning
+// the data read.
+func (e *endpointTester) CheckRead(t *testing.T, count int) []byte {
+	t.Helper()
+	var buf bytes.Buffer
+	res, err := e.ep.Read(&buf, count, tcpip.ReadOptions{})
+	if err != nil {
+		t.Fatalf("ep.Read = _, %s; want _, nil", err)
+	}
+	if diff := cmp.Diff(tcpip.ReadResult{
+		Count: buf.Len(),
+		Total: buf.Len(),
+	}, res, checker.IgnoreCmpPath("ControlMessages")); diff != "" {
+		t.Errorf("ep.Read: unexpected result (-want +got):\n%s", diff)
+	}
+	return buf.Bytes()
+}
+
+// CheckReadFull reads from the endpoint for exactly count bytes.
+func (e *endpointTester) CheckReadFull(t *testing.T, count int, notifyRead <-chan struct{}, timeout time.Duration) []byte {
+	t.Helper()
+	var buf bytes.Buffer
+	var done int
+	for done < count {
+		res, err := e.ep.Read(&buf, count-done, tcpip.ReadOptions{})
+		if err == tcpip.ErrWouldBlock {
+			// Wait for receive to be notified.
+			select {
+			case <-notifyRead:
+			case <-time.After(timeout):
+				t.Fatalf("Timed out waiting for data to arrive")
+			}
+			continue
+		} else if err != nil {
+			t.Fatalf("ep.Read = _, %s; want _, nil", err)
+		}
+		done += res.Count
+	}
+	return buf.Bytes()
+}
+
 const (
 	// defaultMTU is the MTU, in bytes, used throughout the tests, except
 	// where another value is explicitly used. It is chosen to match the MTU
@@ -740,9 +800,7 @@ func TestSimpleReceive(t *testing.T) {
 	c.WQ.EventRegister(&we, waiter.EventIn)
 	defer c.WQ.EventUnregister(&we)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
 
 	data := []byte{1, 2, 3}
 	c.SendPacket(data, &context.Headers{
@@ -762,11 +820,7 @@ func TestSimpleReceive(t *testing.T) {
 	}
 
 	// Receive data.
-	v, _, err := c.EP.Read(nil)
-	if err != nil {
-		t.Fatalf("Read failed: %s", err)
-	}
-
+	v := ept.CheckRead(t, defaultMTU)
 	if !bytes.Equal(data, v) {
 		t.Fatalf("got data = %v, want = %v", v, data)
 	}
@@ -1492,14 +1546,11 @@ func TestSynSent(t *testing.T) {
 				t.Fatal("timed out waiting for packet to arrive")
 			}
 
+			ept := endpointTester{c.EP}
 			if test.reset {
-				if _, _, err := c.EP.Read(nil); err != tcpip.ErrConnectionRefused {
-					t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrConnectionRefused)
-				}
+				ept.CheckReadError(t, tcpip.ErrConnectionRefused)
 			} else {
-				if _, _, err := c.EP.Read(nil); err != tcpip.ErrAborted {
-					t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrAborted)
-				}
+				ept.CheckReadError(t, tcpip.ErrAborted)
 			}
 
 			if got := c.Stack().Stats().TCP.CurrentConnected.Value(); got != 0 {
@@ -1524,9 +1575,8 @@ func TestOutOfOrderReceive(t *testing.T) {
 	c.WQ.EventRegister(&we, waiter.EventIn)
 	defer c.WQ.EventUnregister(&we)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	// Send second half of data first, with seqnum 3 ahead of expected.
 	data := []byte{1, 2, 3, 4, 5, 6}
@@ -1551,9 +1601,7 @@ func TestOutOfOrderReceive(t *testing.T) {
 
 	// Wait 200ms and check that no data has been received.
 	time.Sleep(200 * time.Millisecond)
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	// Send the first 3 bytes now.
 	c.SendPacket(data[:3], &context.Headers{
@@ -1566,24 +1614,7 @@ func TestOutOfOrderReceive(t *testing.T) {
 	})
 
 	// Receive data.
-	read := make([]byte, 0, 6)
-	for len(read) < len(data) {
-		v, _, err := c.EP.Read(nil)
-		if err != nil {
-			if err == tcpip.ErrWouldBlock {
-				// Wait for receive to be notified.
-				select {
-				case <-ch:
-				case <-time.After(5 * time.Second):
-					t.Fatalf("Timed out waiting for data to arrive")
-				}
-				continue
-			}
-			t.Fatalf("Read failed: %s", err)
-		}
-
-		read = append(read, v...)
-	}
+	read := ept.CheckReadFull(t, 6, ch, 5*time.Second)
 
 	// Check that we received the data in proper order.
 	if !bytes.Equal(data, read) {
@@ -1608,9 +1639,8 @@ func TestOutOfOrderFlood(t *testing.T) {
 	rcvBufSz := math.MaxUint16
 	c.CreateConnected(789, 30000, rcvBufSz)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	// Send 100 packets before the actual one that is expected.
 	data := []byte{1, 2, 3, 4, 5, 6}
@@ -1685,9 +1715,8 @@ func TestRstOnCloseWithUnreadData(t *testing.T) {
 	c.WQ.EventRegister(&we, waiter.EventIn)
 	defer c.WQ.EventUnregister(&we)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	data := []byte{1, 2, 3}
 	c.SendPacket(data, &context.Headers{
@@ -1754,9 +1783,8 @@ func TestRstOnCloseWithUnreadDataFinConvertRst(t *testing.T) {
 	c.WQ.EventRegister(&we, waiter.EventIn)
 	defer c.WQ.EventUnregister(&we)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	data := []byte{1, 2, 3}
 	c.SendPacket(data, &context.Headers{
@@ -1837,17 +1865,14 @@ func TestShutdownRead(t *testing.T) {
 
 	c.CreateConnected(789, 30000, -1 /* epRcvBuf */)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	if err := c.EP.Shutdown(tcpip.ShutdownRead); err != nil {
 		t.Fatalf("Shutdown failed: %s", err)
 	}
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrClosedForReceive {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrClosedForReceive)
-	}
+	ept.CheckReadError(t, tcpip.ErrClosedForReceive)
 	var want uint64 = 1
 	if got := c.EP.Stats().(*tcp.Stats).ReadErrors.ReadClosed.Value(); got != want {
 		t.Fatalf("got EP stats Stats.ReadErrors.ReadClosed got %d want %d", got, want)
@@ -1865,10 +1890,8 @@ func TestFullWindowReceive(t *testing.T) {
 	c.WQ.EventRegister(&we, waiter.EventIn)
 	defer c.WQ.EventUnregister(&we)
 
-	_, _, err := c.EP.Read(nil)
-	if err != tcpip.ErrWouldBlock {
-		t.Fatalf("Read failed: %s", err)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	// Fill up the window w/ tcp.SegOverheadFactor*rcvBufSz as netstack multiplies
 	// the provided buffer value by tcp.SegOverheadFactor to calculate the actual
@@ -1905,11 +1928,7 @@ func TestFullWindowReceive(t *testing.T) {
 	)
 
 	// Receive data and check it.
-	v, _, err := c.EP.Read(nil)
-	if err != nil {
-		t.Fatalf("Read failed: %s", err)
-	}
-
+	v := ept.CheckRead(t, defaultMTU)
 	if !bytes.Equal(data, v) {
 		t.Fatalf("got data = %v, want = %v", v, data)
 	}
@@ -1991,8 +2010,9 @@ func TestSmallSegReceiveWindowAdvertisement(t *testing.T) {
 
 	// Read the data so that the subsequent ACK from the endpoint
 	// grows the right edge of the window.
-	if _, _, err := c.EP.Read(nil); err != nil {
-		t.Fatalf("got Read(nil) = %s", err)
+	var buf bytes.Buffer
+	if _, err := c.EP.Read(&buf, math.MaxUint16, tcpip.ReadOptions{}); err != nil {
+		t.Fatalf("c.EP.Read: %s", err)
 	}
 
 	// Check if we have received max uint16 as our advertised
@@ -2027,9 +2047,9 @@ func TestNoWindowShrinking(t *testing.T) {
 	c.WQ.EventRegister(&we, waiter.EventIn)
 	defer c.WQ.EventUnregister(&we)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
+
 	// Send a 1 byte payload so that we can record the current receive window.
 	// Send a payload of half the size of rcvBufSize.
 	seqNum := iss.Add(1)
@@ -2051,11 +2071,7 @@ func TestNoWindowShrinking(t *testing.T) {
 	}
 
 	// Read the 1 byte payload we just sent.
-	v, _, err := c.EP.Read(nil)
-	if err != nil {
-		t.Fatalf("Read failed: %s", err)
-	}
-	if got, want := payload, v; !bytes.Equal(got, want) {
+	if got, want := payload, ept.CheckRead(t, 1); !bytes.Equal(got, want) {
 		t.Fatalf("got data: %v, want: %v", got, want)
 	}
 
@@ -2128,24 +2144,8 @@ func TestNoWindowShrinking(t *testing.T) {
 		),
 	)
 
-	// Wait for receive to be notified.
-	select {
-	case <-ch:
-	case <-time.After(5 * time.Second):
-		t.Fatalf("Timed out waiting for data to arrive")
-	}
-
 	// Receive data and check it.
-	read := make([]byte, 0, rcvBufSize)
-	for len(read) < len(data) {
-		v, _, err := c.EP.Read(nil)
-		if err != nil {
-			t.Fatalf("Read failed: %s", err)
-		}
-
-		read = append(read, v...)
-	}
-
+	read := ept.CheckReadFull(t, len(data), ch, 5*time.Second)
 	if !bytes.Equal(data, read) {
 		t.Fatalf("got data = %v, want = %v", read, data)
 	}
@@ -2569,11 +2569,11 @@ func TestZeroScaledWindowReceive(t *testing.T) {
 	// we need to read at 3 packets.
 	sz := 0
 	for sz < defaultMTU*2 {
-		v, _, err := c.EP.Read(nil)
+		res, err := c.EP.Read(ioutil.Discard, defaultMTU, tcpip.ReadOptions{})
 		if err != nil {
 			t.Fatalf("Read failed: %s", err)
 		}
-		sz += len(v)
+		sz += res.Count
 	}
 
 	checker.IPv4(t, c.GetPacket(),
@@ -3268,13 +3268,13 @@ func TestReceiveOnResetConnection(t *testing.T) {
 
 loop:
 	for {
-		switch _, _, err := c.EP.Read(nil); err {
+		switch _, err := c.EP.Read(ioutil.Discard, defaultMTU, tcpip.ReadOptions{}); err {
 		case tcpip.ErrWouldBlock:
 			select {
 			case <-ch:
 				// Expect the state to be StateError and subsequent Reads to fail with HardError.
-				if _, _, err := c.EP.Read(nil); err != tcpip.ErrConnectionReset {
-					t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrConnectionReset)
+				if _, err := c.EP.Read(ioutil.Discard, math.MaxUint16, tcpip.ReadOptions{}); err != tcpip.ErrConnectionReset {
+					t.Fatalf("got c.EP.Read() = %s, want = %s", err, tcpip.ErrConnectionReset)
 				}
 				break loop
 			case <-time.After(1 * time.Second):
@@ -4164,9 +4164,8 @@ func TestReadAfterClosedState(t *testing.T) {
 	c.WQ.EventRegister(&we, waiter.EventIn)
 	defer c.WQ.EventUnregister(&we)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	// Shutdown immediately for write, check that we get a FIN.
 	if err := c.EP.Shutdown(tcpip.ShutdownWrite); err != nil {
@@ -4224,35 +4223,31 @@ func TestReadAfterClosedState(t *testing.T) {
 	}
 
 	// Check that peek works.
-	peekBuf := make([]byte, 10)
-	n, err := c.EP.Peek([][]byte{peekBuf})
+	var peekBuf bytes.Buffer
+	res, err := c.EP.Read(&peekBuf, 10, tcpip.ReadOptions{Peek: true})
 	if err != nil {
 		t.Fatalf("Peek failed: %s", err)
 	}
 
-	peekBuf = peekBuf[:n]
-	if !bytes.Equal(data, peekBuf) {
-		t.Fatalf("got data = %v, want = %v", peekBuf, data)
+	if got, want := res.Count, len(data); got != want {
+		t.Fatalf("res.Count = %d, want %d", got, want)
 	}
-
-	// Receive data.
-	v, _, err := c.EP.Read(nil)
-	if err != nil {
-		t.Fatalf("Read failed: %s", err)
+	if !bytes.Equal(data, peekBuf.Bytes()) {
+		t.Fatalf("got data = %v, want = %v", peekBuf.Bytes(), data)
 	}
 
+	// Receive data.
+	v := ept.CheckRead(t, defaultMTU)
 	if !bytes.Equal(data, v) {
 		t.Fatalf("got data = %v, want = %v", v, data)
 	}
 
 	// Now that we drained the queue, check that functions fail with the
 	// right error code.
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrClosedForReceive {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrClosedForReceive)
-	}
-
-	if _, err := c.EP.Peek([][]byte{peekBuf}); err != tcpip.ErrClosedForReceive {
-		t.Fatalf("got c.EP.Peek(...) = %s, want = %s", err, tcpip.ErrClosedForReceive)
+	ept.CheckReadError(t, tcpip.ErrClosedForReceive)
+	var buf bytes.Buffer
+	if _, err := c.EP.Read(&buf, 1, tcpip.ReadOptions{Peek: true}); err != tcpip.ErrClosedForReceive {
+		t.Fatalf("c.EP.Read(_, _, {Peek: true}) = %v, %s; want _, %s", res, err, tcpip.ErrClosedForReceive)
 	}
 }
 
@@ -4619,17 +4614,8 @@ func TestSelfConnect(t *testing.T) {
 	// Read back what was written.
 	wq.EventUnregister(&waitEntry)
 	wq.EventRegister(&waitEntry, waiter.EventIn)
-	rd, _, err := ep.Read(nil)
-	if err != nil {
-		if err != tcpip.ErrWouldBlock {
-			t.Fatalf("Read failed: %s", err)
-		}
-		<-notifyCh
-		rd, _, err = ep.Read(nil)
-		if err != nil {
-			t.Fatalf("Read failed: %s", err)
-		}
-	}
+	ept := endpointTester{ep}
+	rd := ept.CheckReadFull(t, len(data), notifyCh, 5*time.Second)
 
 	if !bytes.Equal(data, rd) {
 		t.Fatalf("got data = %v, want = %v", rd, data)
@@ -5082,9 +5068,8 @@ func TestKeepalive(t *testing.T) {
 	}
 
 	// Check that the connection is still alive.
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	// Send some data and wait before ACKing it. Keepalives should be disabled
 	// during this period.
@@ -5173,9 +5158,7 @@ func TestKeepalive(t *testing.T) {
 		t.Errorf("got c.Stack().Stats().TCP.EstablishedTimedout.Value() = %d, want = 1", got)
 	}
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrTimeout {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrTimeout)
-	}
+	ept.CheckReadError(t, tcpip.ErrTimeout)
 
 	if got := c.Stack().Stats().TCP.CurrentEstablished.Value(); got != 0 {
 		t.Errorf("got stats.TCP.CurrentEstablished.Value() = %d, want = 0", got)
@@ -6070,9 +6053,8 @@ func TestEndpointBindListenAcceptState(t *testing.T) {
 		t.Errorf("unexpected endpoint state: want %s, got %s", want, got)
 	}
 
-	if _, _, err := ep.Read(nil); err != tcpip.ErrNotConnected {
-		t.Errorf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrNotConnected)
-	}
+	ept := endpointTester{ep}
+	ept.CheckReadError(t, tcpip.ErrNotConnected)
 	if got := ep.Stats().(*tcp.Stats).ReadErrors.NotConnected.Value(); got != 1 {
 		t.Errorf("got EP stats Stats.ReadErrors.NotConnected got %d want %d", got, 1)
 	}
@@ -6227,7 +6209,7 @@ func TestReceiveBufferAutoTuningApplicationLimited(t *testing.T) {
 	// Now read all the data from the endpoint and verify that advertised
 	// window increases to the full available buffer size.
 	for {
-		_, _, err := c.EP.Read(nil)
+		_, err := c.EP.Read(ioutil.Discard, defaultMTU, tcpip.ReadOptions{})
 		if err == tcpip.ErrWouldBlock {
 			break
 		}
@@ -6351,11 +6333,11 @@ func TestReceiveBufferAutoTuning(t *testing.T) {
 		// to happen before we measure the new window.
 		totalCopied := 0
 		for {
-			b, _, err := c.EP.Read(nil)
+			res, err := c.EP.Read(ioutil.Discard, defaultMTU, tcpip.ReadOptions{})
 			if err == tcpip.ErrWouldBlock {
 				break
 			}
-			totalCopied += len(b)
+			totalCopied += res.Count
 		}
 
 		// Invoke the moderation API. This is required for auto-tuning
@@ -7272,9 +7254,8 @@ func TestTCPUserTimeout(t *testing.T) {
 		),
 	)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrTimeout {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrTimeout)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrTimeout)
 
 	if got, want := c.Stack().Stats().TCP.EstablishedTimedout.Value(), origEstablishedTimedout+1; got != want {
 		t.Errorf("got c.Stack().Stats().TCP.EstablishedTimedout = %d, want = %d", got, want)
@@ -7317,9 +7298,8 @@ func TestKeepaliveWithUserTimeout(t *testing.T) {
 	}
 
 	// Check that the connection is still alive.
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrWouldBlock {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrWouldBlock)
-	}
+	ept := endpointTester{c.EP}
+	ept.CheckReadError(t, tcpip.ErrWouldBlock)
 
 	// Now receive 1 keepalives, but don't ACK it.
 	b := c.GetPacket()
@@ -7358,9 +7338,7 @@ func TestKeepaliveWithUserTimeout(t *testing.T) {
 		),
 	)
 
-	if _, _, err := c.EP.Read(nil); err != tcpip.ErrTimeout {
-		t.Fatalf("got c.EP.Read(nil) = %s, want = %s", err, tcpip.ErrTimeout)
-	}
+	ept.CheckReadError(t, tcpip.ErrTimeout)
 	if got, want := c.Stack().Stats().TCP.EstablishedTimedout.Value(), origEstablishedTimedout+1; got != want {
 		t.Errorf("got c.Stack().Stats().TCP.EstablishedTimedout = %d, want = %d", got, want)
 	}
@@ -7417,11 +7395,11 @@ func TestIncreaseWindowOnRead(t *testing.T) {
 	// defaultMTU is a good enough estimate for the MSS used for this
 	// connection.
 	for read < defaultMTU*2 {
-		v, _, err := c.EP.Read(nil)
+		res, err := c.EP.Read(ioutil.Discard, defaultMTU, tcpip.ReadOptions{})
 		if err != nil {
 			t.Fatalf("Read failed: %s", err)
 		}
-		read += len(v)
+		read += res.Count
 	}
 
 	// After reading > MSS worth of data, we surely crossed MSS. See the ack:
diff --git a/pkg/tcpip/transport/tcp/tcp_timestamp_test.go b/pkg/tcpip/transport/tcp/tcp_timestamp_test.go
index 0f9ed06cd..9e02d467d 100644
--- a/pkg/tcpip/transport/tcp/tcp_timestamp_test.go
+++ b/pkg/tcpip/transport/tcp/tcp_timestamp_test.go
@@ -20,6 +20,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/checker"
@@ -105,11 +106,18 @@ func TestTimeStampEnabledConnect(t *testing.T) {
 	// There should be 5 views to read and each of them should
 	// contain the same data.
 	for i := 0; i < 5; i++ {
-		got, _, err := c.EP.Read(nil)
+		var buf bytes.Buffer
+		result, err := c.EP.Read(&buf, len(data), tcpip.ReadOptions{})
 		if err != nil {
 			t.Fatalf("Unexpected error from Read: %v", err)
 		}
-		if want := data; bytes.Compare(got, want) != 0 {
+		if diff := cmp.Diff(tcpip.ReadResult{
+			Count: buf.Len(),
+			Total: buf.Len(),
+		}, result, checker.IgnoreCmpPath("ControlMessages")); diff != "" {
+			t.Errorf("Read: unexpected result (-want +got):\n%s", diff)
+		}
+		if got, want := buf.Bytes(), data; bytes.Compare(got, want) != 0 {
 			t.Fatalf("Data is different: got: %v, want: %v", got, want)
 		}
 	}
@@ -286,11 +294,18 @@ func TestSegmentNotDroppedWhenTimestampMissing(t *testing.T) {
 	}
 
 	// Issue a read and we should data.
-	got, _, err := c.EP.Read(nil)
+	var buf bytes.Buffer
+	result, err := c.EP.Read(&buf, defaultMTU, tcpip.ReadOptions{})
 	if err != nil {
 		t.Fatalf("Unexpected error from Read: %v", err)
 	}
-	if want := data; bytes.Compare(got, want) != 0 {
+	if diff := cmp.Diff(tcpip.ReadResult{
+		Count: buf.Len(),
+		Total: buf.Len(),
+	}, result, checker.IgnoreCmpPath("ControlMessages")); diff != "" {
+		t.Errorf("Read: unexpected result (-want +got):\n%s", diff)
+	}
+	if got, want := buf.Bytes(), data; bytes.Compare(got, want) != 0 {
 		t.Fatalf("Data is different: got: %v, want: %v", got, want)
 	}
 }
diff --git a/pkg/tcpip/transport/udp/BUILD b/pkg/tcpip/transport/udp/BUILD
index 7ebae63d8..153e8c950 100644
--- a/pkg/tcpip/transport/udp/BUILD
+++ b/pkg/tcpip/transport/udp/BUILD
@@ -58,5 +58,6 @@ go_test(
         "//pkg/tcpip/stack",
         "//pkg/tcpip/transport/icmp",
         "//pkg/waiter",
+        "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 4e8bd8b04..075de1db0 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -16,6 +16,7 @@ package udp
 
 import (
 	"fmt"
+	"io"
 	"sync/atomic"
 
 	"gvisor.dev/gvisor/pkg/sync"
@@ -282,11 +283,10 @@ func (e *endpoint) Close() {
 // ModerateRecvBuf implements tcpip.Endpoint.ModerateRecvBuf.
 func (e *endpoint) ModerateRecvBuf(copied int) {}
 
-// Read reads data from the endpoint. This method does not block if
-// there is no data pending.
-func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+// Read implements tcpip.Endpoint.Read.
+func (e *endpoint) Read(dst io.Writer, count int, opts tcpip.ReadOptions) (tcpip.ReadResult, *tcpip.Error) {
 	if err := e.LastError(); err != nil {
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	e.rcvMu.Lock()
@@ -298,18 +298,17 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 			err = tcpip.ErrClosedForReceive
 		}
 		e.rcvMu.Unlock()
-		return buffer.View{}, tcpip.ControlMessages{}, err
+		return tcpip.ReadResult{}, err
 	}
 
 	p := e.rcvList.Front()
-	e.rcvList.Remove(p)
-	e.rcvBufSize -= p.data.Size()
-	e.rcvMu.Unlock()
-
-	if addr != nil {
-		*addr = p.senderAddress
+	if !opts.Peek {
+		e.rcvList.Remove(p)
+		e.rcvBufSize -= p.data.Size()
 	}
+	e.rcvMu.Unlock()
 
+	// Control Messages
 	cm := tcpip.ControlMessages{
 		HasTimestamp: true,
 		Timestamp:    p.timestamp,
@@ -331,7 +330,22 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 		cm.HasOriginalDstAddress = true
 		cm.OriginalDstAddress = p.destinationAddress
 	}
-	return p.data.ToView(), cm, nil
+
+	// Read Result
+	res := tcpip.ReadResult{
+		Total:           p.data.Size(),
+		ControlMessages: cm,
+	}
+	if opts.NeedRemoteAddr {
+		res.RemoteAddr = p.senderAddress
+	}
+
+	n, err := p.data.ReadTo(dst, count, opts.Peek)
+	if n == 0 && err != nil {
+		return res, tcpip.ErrBadBuffer
+	}
+	res.Count = n
+	return res, nil
 }
 
 // prepareForWrite prepares the endpoint for sending data. In particular, it
@@ -566,11 +580,6 @@ func (e *endpoint) write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-c
 	return int64(len(v)), nil, nil
 }
 
-// Peek only returns data from a single datagram, so do nothing here.
-func (e *endpoint) Peek([][]byte) (int64, *tcpip.Error) {
-	return 0, nil
-}
-
 // OnReuseAddressSet implements tcpip.SocketOptionsHandler.OnReuseAddressSet.
 func (e *endpoint) OnReuseAddressSet(v bool) {
 	e.mu.Lock()
diff --git a/pkg/tcpip/transport/udp/udp_test.go b/pkg/tcpip/transport/udp/udp_test.go
index 8429f34b4..455b8c2aa 100644
--- a/pkg/tcpip/transport/udp/udp_test.go
+++ b/pkg/tcpip/transport/udp/udp_test.go
@@ -18,10 +18,12 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"io/ioutil"
 	"math/rand"
 	"testing"
 	"time"
 
+	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
 	"gvisor.dev/gvisor/pkg/tcpip/checker"
@@ -595,13 +597,13 @@ func testReadInternal(c *testContext, flow testFlow, packetShouldBeDropped, expe
 	// Take a snapshot of the stats to validate them at the end of the test.
 	epstats := c.ep.Stats().(*tcpip.TransportEndpointStats).Clone()
 
-	var addr tcpip.FullAddress
-	v, cm, err := c.ep.Read(&addr)
+	var buf bytes.Buffer
+	res, err := c.ep.Read(&buf, defaultMTU, tcpip.ReadOptions{NeedRemoteAddr: true})
 	if err == tcpip.ErrWouldBlock {
 		// Wait for data to become available.
 		select {
 		case <-ch:
-			v, cm, err = c.ep.Read(&addr)
+			res, err = c.ep.Read(&buf, defaultMTU, tcpip.ReadOptions{NeedRemoteAddr: true})
 
 		case <-time.After(300 * time.Millisecond):
 			if packetShouldBeDropped {
@@ -621,23 +623,32 @@ func testReadInternal(c *testContext, flow testFlow, packetShouldBeDropped, expe
 	}
 
 	if packetShouldBeDropped {
-		c.t.Fatalf("Read unexpectedly received data from %s", addr.Addr)
+		c.t.Fatalf("Read unexpectedly received data from %s", res.RemoteAddr.Addr)
 	}
 
-	// Check the peer address.
+	// Check the read result.
 	h := flow.header4Tuple(incoming)
-	if addr.Addr != h.srcAddr.Addr {
-		c.t.Fatalf("got address = %s, want = %s", addr.Addr, h.srcAddr.Addr)
+	if diff := cmp.Diff(tcpip.ReadResult{
+		Count:      buf.Len(),
+		Total:      buf.Len(),
+		RemoteAddr: tcpip.FullAddress{Addr: h.srcAddr.Addr},
+	}, res, checker.IgnoreCmpPath(
+		"ControlMessages", // ControlMessages will be checked later.
+		"RemoteAddr.NIC",
+		"RemoteAddr.Port",
+	)); diff != "" {
+		c.t.Fatalf("Read: unexpected result (-want +got):\n%s", diff)
 	}
 
 	// Check the payload.
+	v := buf.Bytes()
 	if !bytes.Equal(payload, v) {
 		c.t.Fatalf("got payload = %x, want = %x", v, payload)
 	}
 
 	// Run any checkers against the ControlMessages.
 	for _, f := range checkers {
-		f(c.t, cm)
+		f(c.t, res.ControlMessages)
 	}
 
 	c.checkEndpointReadStats(1, epstats, err)
@@ -828,8 +839,8 @@ func TestV4ReadSelfSource(t *testing.T) {
 				t.Errorf("c.s.Stats().IP.InvalidSourceAddressesReceived got %d, want %d", got, tt.wantInvalidSource)
 			}
 
-			if _, _, err := c.ep.Read(nil); err != tt.wantErr {
-				t.Errorf("got c.ep.Read(nil) = %s, want = %s", err, tt.wantErr)
+			if _, err := c.ep.Read(ioutil.Discard, defaultMTU, tcpip.ReadOptions{}); err != tt.wantErr {
+				t.Errorf("got c.ep.Read = %s, want = %s", err, tt.wantErr)
 			}
 		})
 	}