Vendor dependencies with dep

vendor/golang.org/x/net/bpf/vm_test.go

@@ -0,0 +1,144 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bpf_test
+
+import (
+	"fmt"
+	"testing"
+
+	"golang.org/x/net/bpf"
+)
+
+var _ bpf.Instruction = unknown{}
+
+type unknown struct{}
+
+func (unknown) Assemble() (bpf.RawInstruction, error) {
+	return bpf.RawInstruction{}, nil
+}
+
+func TestVMUnknownInstruction(t *testing.T) {
+	vm, done, err := testVM(t, []bpf.Instruction{
+		bpf.LoadConstant{
+			Dst: bpf.RegA,
+			Val: 100,
+		},
+		// Should terminate the program with an error immediately
+		unknown{},
+		bpf.RetA{},
+	})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	defer done()
+
+	_, err = vm.Run([]byte{
+		0xff, 0xff, 0xff, 0xff,
+		0xff, 0xff, 0xff, 0xff,
+		0x00, 0x00,
+	})
+	if errStr(err) != "unknown Instruction at index 1: bpf_test.unknown" {
+		t.Fatalf("unexpected error while running program: %v", err)
+	}
+}
+
+func TestVMNoReturnInstruction(t *testing.T) {
+	_, _, err := testVM(t, []bpf.Instruction{
+		bpf.LoadConstant{
+			Dst: bpf.RegA,
+			Val: 1,
+		},
+	})
+	if errStr(err) != "BPF program must end with RetA or RetConstant" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestVMNoInputInstructions(t *testing.T) {
+	_, _, err := testVM(t, []bpf.Instruction{})
+	if errStr(err) != "one or more Instructions must be specified" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+// ExampleNewVM demonstrates usage of a VM, using an Ethernet frame
+// as input and checking its EtherType to determine if it should be accepted.
+func ExampleNewVM() {
+	// Offset | Length | Comment
+	// -------------------------
+	//   00   |   06   | Ethernet destination MAC address
+	//   06   |   06   | Ethernet source MAC address
+	//   12   |   02   | Ethernet EtherType
+	const (
+		etOff = 12
+		etLen = 2
+
+		etARP = 0x0806
+	)
+
+	// Set up a VM to filter traffic based on if its EtherType
+	// matches the ARP EtherType.
+	vm, err := bpf.NewVM([]bpf.Instruction{
+		// Load EtherType value from Ethernet header
+		bpf.LoadAbsolute{
+			Off:  etOff,
+			Size: etLen,
+		},
+		// If EtherType is equal to the ARP EtherType, jump to allow
+		// packet to be accepted
+		bpf.JumpIf{
+			Cond:     bpf.JumpEqual,
+			Val:      etARP,
+			SkipTrue: 1,
+		},
+		// EtherType does not match the ARP EtherType
+		bpf.RetConstant{
+			Val: 0,
+		},
+		// EtherType matches the ARP EtherType, accept up to 1500
+		// bytes of packet
+		bpf.RetConstant{
+			Val: 1500,
+		},
+	})
+	if err != nil {
+		panic(fmt.Sprintf("failed to load BPF program: %v", err))
+	}
+
+	// Create an Ethernet frame with the ARP EtherType for testing
+	frame := []byte{
+		0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		0x00, 0x11, 0x22, 0x33, 0x44, 0x55,
+		0x08, 0x06,
+		// Payload omitted for brevity
+	}
+
+	// Run our VM's BPF program using the Ethernet frame as input
+	out, err := vm.Run(frame)
+	if err != nil {
+		panic(fmt.Sprintf("failed to accept Ethernet frame: %v", err))
+	}
+
+	// BPF VM can return a byte count greater than the number of input
+	// bytes, so trim the output to match the input byte length
+	if out > len(frame) {
+		out = len(frame)
+	}
+
+	fmt.Printf("out: %d bytes", out)
+
+	// Output:
+	// out: 14 bytes
+}
+
+// errStr returns the string representation of an error, or
+// "<nil>" if it is nil.
+func errStr(err error) string {
+	if err == nil {
+		return "<nil>"
+	}
+
+	return err.Error()
+}