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| 1 | +// Copyright 2016 The Go Authors. All rights reserved. |
| 2 | +// Use of this source code is governed by a BSD-style |
| 3 | +// license that can be found in the LICENSE file. |
| 4 | + |
| 5 | +package ipv6_test |
| 6 | + |
| 7 | +import ( |
| 8 | + "net" |
| 9 | + "runtime" |
| 10 | + "testing" |
| 11 | + "time" |
| 12 | + |
| 13 | + "golang.org/x/net/bpf" |
| 14 | + "golang.org/x/net/ipv6" |
| 15 | +) |
| 16 | + |
| 17 | +func TestBPF(t *testing.T) { |
| 18 | + if runtime.GOOS != "linux" { |
| 19 | + t.Skipf("not supported on %s", runtime.GOOS) |
| 20 | + } |
| 21 | + |
| 22 | + l, err := net.ListenPacket("udp6", "[::1]:0") |
| 23 | + if err != nil { |
| 24 | + t.Fatal(err) |
| 25 | + } |
| 26 | + defer l.Close() |
| 27 | + |
| 28 | + p := ipv6.NewPacketConn(l) |
| 29 | + |
| 30 | + // This filter accepts UDP packets whose first payload byte is |
| 31 | + // even. |
| 32 | + prog, err := bpf.Assemble([]bpf.Instruction{ |
| 33 | + // Load the first byte of the payload (skipping UDP header). |
| 34 | + bpf.LoadAbsolute{Off: 8, Size: 1}, |
| 35 | + // Select LSB of the byte. |
| 36 | + bpf.ALUOpConstant{Op: bpf.ALUOpAnd, Val: 1}, |
| 37 | + // Byte is even? |
| 38 | + bpf.JumpIf{Cond: bpf.JumpEqual, Val: 0, SkipFalse: 1}, |
| 39 | + // Accept. |
| 40 | + bpf.RetConstant{Val: 4096}, |
| 41 | + // Ignore. |
| 42 | + bpf.RetConstant{Val: 0}, |
| 43 | + }) |
| 44 | + if err != nil { |
| 45 | + t.Fatalf("compiling BPF: %s", err) |
| 46 | + } |
| 47 | + |
| 48 | + if err = p.SetBPF(prog); err != nil { |
| 49 | + t.Fatalf("attaching filter to Conn: %s", err) |
| 50 | + } |
| 51 | + |
| 52 | + s, err := net.Dial("udp6", l.LocalAddr().String()) |
| 53 | + if err != nil { |
| 54 | + t.Fatal(err) |
| 55 | + } |
| 56 | + defer s.Close() |
| 57 | + go func() { |
| 58 | + for i := byte(0); i < 10; i++ { |
| 59 | + s.Write([]byte{i}) |
| 60 | + } |
| 61 | + }() |
| 62 | + |
| 63 | + l.SetDeadline(time.Now().Add(2 * time.Second)) |
| 64 | + seen := make([]bool, 5) |
| 65 | + for { |
| 66 | + var b [512]byte |
| 67 | + n, _, err := l.ReadFrom(b[:]) |
| 68 | + if err != nil { |
| 69 | + t.Fatalf("reading from listener: %s", err) |
| 70 | + } |
| 71 | + if n != 1 { |
| 72 | + t.Fatalf("unexpected packet length, want 1, got %d", n) |
| 73 | + } |
| 74 | + if b[0] >= 10 { |
| 75 | + t.Fatalf("unexpected byte, want 0-9, got %d", b[0]) |
| 76 | + } |
| 77 | + if b[0]%2 != 0 { |
| 78 | + t.Fatalf("got odd byte %d, wanted only even bytes", b[0]) |
| 79 | + } |
| 80 | + seen[b[0]/2] = true |
| 81 | + |
| 82 | + seenAll := true |
| 83 | + for _, v := range seen { |
| 84 | + if !v { |
| 85 | + seenAll = false |
| 86 | + break |
| 87 | + } |
| 88 | + } |
| 89 | + if seenAll { |
| 90 | + break |
| 91 | + } |
| 92 | + } |
| 93 | +} |
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