1// Copyright 2009 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
5package crc32
6
7import (
8	"encoding"
9	"fmt"
10	"hash"
11	"io"
12	"math/rand"
13	"testing"
14)
15
16// First test, so that it can be the one to initialize castagnoliTable.
17func TestCastagnoliRace(t *testing.T) {
18	// The MakeTable(Castagnoli) lazily initializes castagnoliTable,
19	// which races with the switch on tab during Write to check
20	// whether tab == castagnoliTable.
21	ieee := NewIEEE()
22	go MakeTable(Castagnoli)
23	ieee.Write([]byte("hello"))
24}
25
26type test struct {
27	ieee, castagnoli    uint32
28	in                  string
29	halfStateIEEE       string // IEEE marshaled hash state after first half of in written, used by TestGoldenMarshal
30	halfStateCastagnoli string // Castagnoli marshaled hash state after first half of in written, used by TestGoldenMarshal
31}
32
33var golden = []test{
34	{0x0, 0x0, "", "crc\x01ʇ\x91M\x00\x00\x00\x00", "crc\x01wB\x84\x81\x00\x00\x00\x00"},
35	{0xe8b7be43, 0xc1d04330, "a", "crc\x01ʇ\x91M\x00\x00\x00\x00", "crc\x01wB\x84\x81\x00\x00\x00\x00"},
36	{0x9e83486d, 0xe2a22936, "ab", "crc\x01ʇ\x91M跾C", "crc\x01wB\x84\x81\xc1\xd0C0"},
37	{0x352441c2, 0x364b3fb7, "abc", "crc\x01ʇ\x91M跾C", "crc\x01wB\x84\x81\xc1\xd0C0"},
38	{0xed82cd11, 0x92c80a31, "abcd", "crc\x01ʇ\x91M\x9e\x83Hm", "crc\x01wB\x84\x81\xe2\xa2)6"},
39	{0x8587d865, 0xc450d697, "abcde", "crc\x01ʇ\x91M\x9e\x83Hm", "crc\x01wB\x84\x81\xe2\xa2)6"},
40	{0x4b8e39ef, 0x53bceff1, "abcdef", "crc\x01ʇ\x91M5$A\xc2", "crc\x01wB\x84\x816K?\xb7"},
41	{0x312a6aa6, 0xe627f441, "abcdefg", "crc\x01ʇ\x91M5$A\xc2", "crc\x01wB\x84\x816K?\xb7"},
42	{0xaeef2a50, 0xa9421b7, "abcdefgh", "crc\x01ʇ\x91M\xed\x82\xcd\x11", "crc\x01wB\x84\x81\x92\xc8\n1"},
43	{0x8da988af, 0x2ddc99fc, "abcdefghi", "crc\x01ʇ\x91M\xed\x82\xcd\x11", "crc\x01wB\x84\x81\x92\xc8\n1"},
44	{0x3981703a, 0xe6599437, "abcdefghij", "crc\x01ʇ\x91M\x85\x87\xd8e", "crc\x01wB\x84\x81\xc4P֗"},
45	{0x6b9cdfe7, 0xb2cc01fe, "Discard medicine more than two years old.", "crc\x01ʇ\x91M\xfd\xe5\xc2J", "crc\x01wB\x84\x81S\"(\xe0"},
46	{0xc90ef73f, 0xe28207f, "He who has a shady past knows that nice guys finish last.", "crc\x01ʇ\x91M\x01Nj+", "crc\x01wB\x84\x81'\xdaR\x15"},
47	{0xb902341f, 0xbe93f964, "I wouldn't marry him with a ten foot pole.", "crc\x01ʇ\x91M\x9d\x13\xce\x10", "crc\x01wB\x84\x81\xc3\xed\xabG"},
48	{0x42080e8, 0x9e3be0c3, "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave", "crc\x01ʇ\x91M-\xed\xf7\x94", "crc\x01wB\x84\x81\xce\xceb\x81"},
49	{0x154c6d11, 0xf505ef04, "The days of the digital watch are numbered.  -Tom Stoppard", "crc\x01ʇ\x91MOa\xa5\r", "crc\x01wB\x84\x81\xd3s\x9dP"},
50	{0x4c418325, 0x85d3dc82, "Nepal premier won't resign.", "crc\x01ʇ\x91M\xa8S9\x85", "crc\x01wB\x84\x81{\x90\x8a\x14"},
51	{0x33955150, 0xc5142380, "For every action there is an equal and opposite government program.", "crc\x01ʇ\x91Ma\xe9>\x86", "crc\x01wB\x84\x81\xaa@\xc4\x1c"},
52	{0x26216a4b, 0x75eb77dd, "His money is twice tainted: 'taint yours and 'taint mine.", "crc\x01ʇ\x91M\\\x1an\x88", "crc\x01wB\x84\x81W\a8Z"},
53	{0x1abbe45e, 0x91ebe9f7, "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977", "crc\x01ʇ\x91M\xb7\xf5\xf2\xca", "crc\x01wB\x84\x81\xc4o\x9d\x85"},
54	{0xc89a94f7, 0xf0b1168e, "It's a tiny change to the code and not completely disgusting. - Bob Manchek", "crc\x01ʇ\x91M\x84g1\xe8", "crc\x01wB\x84\x81#\x98\f\xab"},
55	{0xab3abe14, 0x572b74e2, "size:  a.out:  bad magic", "crc\x01ʇ\x91M\x8a\x0f\xad\b", "crc\x01wB\x84\x81\x80\xc9n\xd8"},
56	{0xbab102b6, 0x8a58a6d5, "The major problem is with sendmail.  -Mark Horton", "crc\x01ʇ\x91M\a\xf0\xb3\x15", "crc\x01wB\x84\x81liS\xcc"},
57	{0x999149d7, 0x9c426c50, "Give me a rock, paper and scissors and I will move the world.  CCFestoon", "crc\x01ʇ\x91M\x0fa\xbc.", "crc\x01wB\x84\x81\xdb͏C"},
58	{0x6d52a33c, 0x735400a4, "If the enemy is within range, then so are you.", "crc\x01ʇ\x91My\x1b\x99\xf8", "crc\x01wB\x84\x81\xaaB\x037"},
59	{0x90631e8d, 0xbec49c95, "It's well we cannot hear the screams/That we create in others' dreams.", "crc\x01ʇ\x91M\bqfY", "crc\x01wB\x84\x81\x16y\xa1\xd2"},
60	{0x78309130, 0xa95a2079, "You remind me of a TV show, but that's all right: I watch it anyway.", "crc\x01ʇ\x91M\xbdO,\xc2", "crc\x01wB\x84\x81f&\xc5\xe4"},
61	{0x7d0a377f, 0xde2e65c5, "C is as portable as Stonehedge!!", "crc\x01ʇ\x91M\xf7\xd6\x00\xd5", "crc\x01wB\x84\x81de\\\xf8"},
62	{0x8c79fd79, 0x297a88ed, "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley", "crc\x01ʇ\x91Ml+\xb8\xa7", "crc\x01wB\x84\x81\xbf\xd6S\xdd"},
63	{0xa20b7167, 0x66ed1d8b, "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction.  Lewis-Randall Rule", "crc\x01ʇ\x91M<lR[", "crc\x01wB\x84\x81{\xaco\xb1"},
64	{0x8e0bb443, 0xdcded527, "How can you write a big system without C++?  -Paul Glick", "crc\x01ʇ\x91M\x0e\x88\x89\xed", "crc\x01wB\x84\x813\xd7C\u007f"},
65}
66
67// testGoldenIEEE verifies that the given function returns
68// correct IEEE checksums.
69func testGoldenIEEE(t *testing.T, crcFunc func(b []byte) uint32) {
70	for _, g := range golden {
71		if crc := crcFunc([]byte(g.in)); crc != g.ieee {
72			t.Errorf("IEEE(%s) = 0x%x want 0x%x", g.in, crc, g.ieee)
73		}
74	}
75}
76
77// testGoldenCastagnoli verifies that the given function returns
78// correct IEEE checksums.
79func testGoldenCastagnoli(t *testing.T, crcFunc func(b []byte) uint32) {
80	for _, g := range golden {
81		if crc := crcFunc([]byte(g.in)); crc != g.castagnoli {
82			t.Errorf("Castagnoli(%s) = 0x%x want 0x%x", g.in, crc, g.castagnoli)
83		}
84	}
85}
86
87// testCrossCheck generates random buffers of various lengths and verifies that
88// the two "update" functions return the same result.
89func testCrossCheck(t *testing.T, crcFunc1, crcFunc2 func(crc uint32, b []byte) uint32) {
90	// The AMD64 implementation has some cutoffs at lengths 168*3=504 and
91	// 1344*3=4032. We should make sure lengths around these values are in the
92	// list.
93	lengths := []int{0, 1, 2, 3, 4, 5, 10, 16, 50, 63, 64, 65, 100,
94		127, 128, 129, 255, 256, 257, 300, 312, 384, 416, 448, 480,
95		500, 501, 502, 503, 504, 505, 512, 513, 1000, 1024, 2000,
96		4030, 4031, 4032, 4033, 4036, 4040, 4048, 4096, 5000, 10000}
97	for _, length := range lengths {
98		p := make([]byte, length)
99		_, _ = rand.Read(p)
100		crcInit := uint32(rand.Int63())
101		crc1 := crcFunc1(crcInit, p)
102		crc2 := crcFunc2(crcInit, p)
103		if crc1 != crc2 {
104			t.Errorf("mismatch: 0x%x vs 0x%x (buffer length %d)", crc1, crc2, length)
105		}
106	}
107}
108
109// TestSimple tests the simple generic algorithm.
110func TestSimple(t *testing.T) {
111	tab := simpleMakeTable(IEEE)
112	testGoldenIEEE(t, func(b []byte) uint32 {
113		return simpleUpdate(0, tab, b)
114	})
115
116	tab = simpleMakeTable(Castagnoli)
117	testGoldenCastagnoli(t, func(b []byte) uint32 {
118		return simpleUpdate(0, tab, b)
119	})
120}
121
122func TestGoldenMarshal(t *testing.T) {
123	t.Run("IEEE", func(t *testing.T) {
124		for _, g := range golden {
125			h := New(IEEETable)
126			h2 := New(IEEETable)
127
128			io.WriteString(h, g.in[:len(g.in)/2])
129
130			state, err := h.(encoding.BinaryMarshaler).MarshalBinary()
131			if err != nil {
132				t.Errorf("could not marshal: %v", err)
133				continue
134			}
135
136			if string(state) != g.halfStateIEEE {
137				t.Errorf("IEEE(%q) state = %q, want %q", g.in, state, g.halfStateIEEE)
138				continue
139			}
140
141			if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
142				t.Errorf("could not unmarshal: %v", err)
143				continue
144			}
145
146			io.WriteString(h, g.in[len(g.in)/2:])
147			io.WriteString(h2, g.in[len(g.in)/2:])
148
149			if h.Sum32() != h2.Sum32() {
150				t.Errorf("IEEE(%s) = 0x%x != marshaled 0x%x", g.in, h.Sum32(), h2.Sum32())
151			}
152		}
153	})
154	t.Run("Castagnoli", func(t *testing.T) {
155		table := MakeTable(Castagnoli)
156		for _, g := range golden {
157			h := New(table)
158			h2 := New(table)
159
160			io.WriteString(h, g.in[:len(g.in)/2])
161
162			state, err := h.(encoding.BinaryMarshaler).MarshalBinary()
163			if err != nil {
164				t.Errorf("could not marshal: %v", err)
165				continue
166			}
167
168			if string(state) != g.halfStateCastagnoli {
169				t.Errorf("Castagnoli(%q) state = %q, want %q", g.in, state, g.halfStateCastagnoli)
170				continue
171			}
172
173			if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
174				t.Errorf("could not unmarshal: %v", err)
175				continue
176			}
177
178			io.WriteString(h, g.in[len(g.in)/2:])
179			io.WriteString(h2, g.in[len(g.in)/2:])
180
181			if h.Sum32() != h2.Sum32() {
182				t.Errorf("Castagnoli(%s) = 0x%x != marshaled 0x%x", g.in, h.Sum32(), h2.Sum32())
183			}
184		}
185	})
186}
187
188func TestMarshalTableMismatch(t *testing.T) {
189	h1 := New(IEEETable)
190	h2 := New(MakeTable(Castagnoli))
191
192	state1, err := h1.(encoding.BinaryMarshaler).MarshalBinary()
193	if err != nil {
194		t.Errorf("could not marshal: %v", err)
195	}
196
197	if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state1); err == nil {
198		t.Errorf("no error when one was expected")
199	}
200}
201
202// TestSlicing tests the slicing-by-8 algorithm.
203func TestSlicing(t *testing.T) {
204	tab := slicingMakeTable(IEEE)
205	testGoldenIEEE(t, func(b []byte) uint32 {
206		return slicingUpdate(0, tab, b)
207	})
208
209	tab = slicingMakeTable(Castagnoli)
210	testGoldenCastagnoli(t, func(b []byte) uint32 {
211		return slicingUpdate(0, tab, b)
212	})
213
214	// Cross-check various polys against the simple algorithm.
215	for _, poly := range []uint32{IEEE, Castagnoli, Koopman, 0xD5828281} {
216		t1 := simpleMakeTable(poly)
217		f1 := func(crc uint32, b []byte) uint32 {
218			return simpleUpdate(crc, t1, b)
219		}
220		t2 := slicingMakeTable(poly)
221		f2 := func(crc uint32, b []byte) uint32 {
222			return slicingUpdate(crc, t2, b)
223		}
224		testCrossCheck(t, f1, f2)
225	}
226}
227
228func TestArchIEEE(t *testing.T) {
229	if !archAvailableIEEE() {
230		t.Skip("Arch-specific IEEE not available.")
231	}
232	archInitIEEE()
233	slicingTable := slicingMakeTable(IEEE)
234	testCrossCheck(t, archUpdateIEEE, func(crc uint32, b []byte) uint32 {
235		return slicingUpdate(crc, slicingTable, b)
236	})
237}
238
239func TestArchCastagnoli(t *testing.T) {
240	if !archAvailableCastagnoli() {
241		t.Skip("Arch-specific Castagnoli not available.")
242	}
243	archInitCastagnoli()
244	slicingTable := slicingMakeTable(Castagnoli)
245	testCrossCheck(t, archUpdateCastagnoli, func(crc uint32, b []byte) uint32 {
246		return slicingUpdate(crc, slicingTable, b)
247	})
248}
249
250func TestGolden(t *testing.T) {
251	testGoldenIEEE(t, ChecksumIEEE)
252
253	// Some implementations have special code to deal with misaligned
254	// data; test that as well.
255	for delta := 1; delta <= 7; delta++ {
256		testGoldenIEEE(t, func(b []byte) uint32 {
257			ieee := NewIEEE()
258			d := delta
259			if d >= len(b) {
260				d = len(b)
261			}
262			ieee.Write(b[:d])
263			ieee.Write(b[d:])
264			return ieee.Sum32()
265		})
266	}
267
268	castagnoliTab := MakeTable(Castagnoli)
269	if castagnoliTab == nil {
270		t.Errorf("nil Castagnoli Table")
271	}
272
273	testGoldenCastagnoli(t, func(b []byte) uint32 {
274		castagnoli := New(castagnoliTab)
275		castagnoli.Write(b)
276		return castagnoli.Sum32()
277	})
278
279	// Some implementations have special code to deal with misaligned
280	// data; test that as well.
281	for delta := 1; delta <= 7; delta++ {
282		testGoldenCastagnoli(t, func(b []byte) uint32 {
283			castagnoli := New(castagnoliTab)
284			d := delta
285			if d >= len(b) {
286				d = len(b)
287			}
288			castagnoli.Write(b[:d])
289			castagnoli.Write(b[d:])
290			return castagnoli.Sum32()
291		})
292	}
293}
294
295func BenchmarkCRC32(b *testing.B) {
296	b.Run("poly=IEEE", benchmarkAll(NewIEEE()))
297	b.Run("poly=Castagnoli", benchmarkAll(New(MakeTable(Castagnoli))))
298	b.Run("poly=Koopman", benchmarkAll(New(MakeTable(Koopman))))
299}
300
301func benchmarkAll(h hash.Hash32) func(b *testing.B) {
302	return func(b *testing.B) {
303		for _, size := range []int{15, 40, 512, 1 << 10, 4 << 10, 32 << 10} {
304			name := fmt.Sprint(size)
305			if size >= 1024 {
306				name = fmt.Sprintf("%dkB", size/1024)
307			}
308			b.Run("size="+name, func(b *testing.B) {
309				for align := 0; align <= 1; align++ {
310					b.Run(fmt.Sprintf("align=%d", align), func(b *testing.B) {
311						benchmark(b, h, int64(size), int64(align))
312					})
313				}
314			})
315		}
316	}
317}
318
319func benchmark(b *testing.B, h hash.Hash32, n, alignment int64) {
320	b.SetBytes(n)
321	data := make([]byte, n+alignment)
322	data = data[alignment:]
323	for i := range data {
324		data[i] = byte(i)
325	}
326	in := make([]byte, 0, h.Size())
327
328	// Warm up
329	h.Reset()
330	h.Write(data)
331	h.Sum(in)
332	// Avoid further allocations
333	in = in[:0]
334
335	b.ResetTimer()
336	for i := 0; i < b.N; i++ {
337		h.Reset()
338		h.Write(data)
339		h.Sum(in)
340		in = in[:0]
341	}
342}
343