Make fragmentation return a reassembled PacketBuffer

This allows later decoupling of the backing network buffer implementation.

PiperOrigin-RevId: 354643297

4 files changed, 46 insertions, 0 deletions

diff --git a/pkg/tcpip/buffer/BUILD b/pkg/tcpip/buffer/BUILD
index c9bcf9326..23aa0ad05 100644
--- a/pkg/tcpip/buffer/BUILD
+++ b/pkg/tcpip/buffer/BUILD
@@ -7,6 +7,7 @@ go_library(
     srcs = [
         "prependable.go",
         "view.go",
+        "view_unsafe.go",
     ],
     visibility = ["//visibility:public"],
 )
diff --git a/pkg/tcpip/buffer/view.go b/pkg/tcpip/buffer/view.go
index 91cc62cc8..b05e81526 100644
--- a/pkg/tcpip/buffer/view.go
+++ b/pkg/tcpip/buffer/view.go
@@ -239,6 +239,16 @@ func (vv *VectorisedView) Size() int {
 	return vv.size
 }
 
+// MemSize returns the estimation size of the vv in memory, including backing
+// buffer data.
+func (vv *VectorisedView) MemSize() int {
+	var size int
+	for _, v := range vv.views {
+		size += cap(v)
+	}
+	return size + cap(vv.views)*viewStructSize + vectorisedViewStructSize
+}
+
 // ToView returns a single view containing the content of the vectorised view.
 //
 // If the vectorised view contains a single view, that view will be returned
diff --git a/pkg/tcpip/buffer/view_test.go b/pkg/tcpip/buffer/view_test.go
index e7f7cc9f1..78b2faa26 100644
--- a/pkg/tcpip/buffer/view_test.go
+++ b/pkg/tcpip/buffer/view_test.go
@@ -20,6 +20,7 @@ import (
 	"io"
 	"reflect"
 	"testing"
+	"unsafe"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
@@ -578,3 +579,15 @@ func TestAppendView(t *testing.T) {
 		}
 	}
 }
+
+func TestMemSize(t *testing.T) {
+	const perViewCap = 128
+	views := make([]buffer.View, 2, 32)
+	views[0] = make(buffer.View, 10, perViewCap)
+	views[1] = make(buffer.View, 20, perViewCap)
+	vv := buffer.NewVectorisedView(30, views)
+	want := int(unsafe.Sizeof(vv)) + cap(views)*int(unsafe.Sizeof(views)) + 2*perViewCap
+	if got := vv.MemSize(); got != want {
+		t.Errorf("vv.MemSize() = %d, want %d", got, want)
+	}
+}
diff --git a/pkg/tcpip/buffer/view_unsafe.go b/pkg/tcpip/buffer/view_unsafe.go
new file mode 100644
index 000000000..75ccd40f8
--- /dev/null
+++ b/pkg/tcpip/buffer/view_unsafe.go
@@ -0,0 +1,22 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package buffer
+
+import "unsafe"
+
+const (
+	vectorisedViewStructSize = int(unsafe.Sizeof(VectorisedView{}))
+	viewStructSize           = int(unsafe.Sizeof(View{}))
+)