hpack_string_util_test.cc revision 5d1f7b1de12d16ceb2c938c56701a3e8bfa558f7 
1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "net/spdy/hpack_string_util.h"
6
7#include <cstddef>
8#include <cstring>
9
10#include "base/basictypes.h"
11#include "base/logging.h"
12#include "base/strings/string_piece.h"
13#include "testing/gtest/include/gtest/gtest.h"
14
15namespace net {
16
17namespace {
18
19using std::string;
20
21// Make sure StringPiecesEqualConstantTime() behaves like the regular
22// string equality operator.
23TEST(HpackStringUtilTest, StringPiecesEqualConstantTime) {
24  EXPECT_TRUE(StringPiecesEqualConstantTime("foo", "foo"));
25  EXPECT_FALSE(StringPiecesEqualConstantTime("foo", "foox"));
26  EXPECT_FALSE(StringPiecesEqualConstantTime("foo", "bar"));
27}
28
29// TODO(jgraettinger): Support this benchmark.
30/*
31enum BM_StringPieceEqualityType {
32  STRCMP_EQUAL,
33  STRCMP_FIRST_CHAR_DIFFERS,
34  STRING_PIECES_EQUAL_CONSTANT_TIME_EQUAL,
35  STRING_PIECES_EQUAL_CONSTANT_TIME_FIRST_CHAR_DIFFERS,
36};
37
38void BM_StringPieceEquality(int iters, int size, int type_int) {
39  BM_StringPieceEqualityType type =
40      static_cast<BM_StringPieceEqualityType>(type_int);
41  string str_a(size, 'x');
42  string str_b(size, 'x');
43  int result = 0;
44  switch (type) {
45    case STRCMP_EQUAL:
46      for (int i = 0; i < iters; ++i) {
47        result |= std::strcmp(str_a.c_str(), str_b.c_str());
48      }
49      CHECK_EQ(result, 0);
50      return;
51
52    case STRCMP_FIRST_CHAR_DIFFERS:
53      str_b[0] = 'y';
54      for (int i = 0; i < iters; ++i) {
55        result |= std::strcmp(str_a.c_str(), str_b.c_str());
56      }
57      CHECK_LT(result, 0);
58      return;
59
60    case STRING_PIECES_EQUAL_CONSTANT_TIME_EQUAL:
61      for (int i = 0; i < iters; ++i) {
62        result |= StringPiecesEqualConstantTime(str_a, str_b);
63      }
64      CHECK_EQ(result, 1);
65      return;
66
67    case STRING_PIECES_EQUAL_CONSTANT_TIME_FIRST_CHAR_DIFFERS:
68      str_b[0] = 'y';
69      for (int i = 0; i < iters; ++i) {
70        result |= StringPiecesEqualConstantTime(str_a, str_b);
71      }
72      CHECK_EQ(result, 0);
73      return;
74  }
75
76  DCHECK(false);
77}
78
79// Results should resemble the table below, where 0 and 1 are clearly
80// different (STRCMP), but 2 and 3 are roughly the same
81// (STRING_PIECES_EQUAL_CONSTANT_TIME).
82//
83// DEBUG: Benchmark                     Time(ns)    CPU(ns) Iterations
84// -------------------------------------------------------------------
85// DEBUG: BM_StringPieceEquality/1M/0      77796      77141       7778
86// DEBUG: BM_StringPieceEquality/1M/1         10         10   70000000
87// DEBUG: BM_StringPieceEquality/1M/2    7729735    7700000        100
88// DEBUG: BM_StringPieceEquality/1M/3    7803051    7800000        100
89BENCHMARK(BM_StringPieceEquality)
90  ->ArgPair(1<<20, STRCMP_EQUAL)
91  ->ArgPair(1<<20, STRCMP_FIRST_CHAR_DIFFERS)
92  ->ArgPair(1<<20, STRING_PIECES_EQUAL_CONSTANT_TIME_EQUAL)
93  ->ArgPair(1<<20, STRING_PIECES_EQUAL_CONSTANT_TIME_FIRST_CHAR_DIFFERS);
94*/
95
96}  // namespace
97
98}  // namespace net
99