Isolates generic DnsClient from AsyncHostResolver.

DnsClient provides a generic DNS client that allows fetching resource records. 
DnsClient is very lightweight and does not support aggregation, queuing or 
prioritization of requests. 

This is the first CL in a series to merge AsyncHostResolver into 
HostResolverImpl. 

Also introduces general-purpose BigEndianReader/Writer. 

BUG=90881
TEST=./net_unittests


Review URL: http://codereview.chromium.org/8762001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113282 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 100 insertions, 0 deletions

diff --git a/net/base/big_endian_unittest.cc b/net/base/big_endian_unittest.cc
new file mode 100644
index 0000000..cb4a6d4
--- /dev/null
+++ b/net/base/big_endian_unittest.cc
@@ -0,0 +1,100 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/string_piece.h"
+#include "net/base/big_endian.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+TEST(BigEndianReaderTest, ReadsValues) {
+  char data[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xA, 0xB, 0xC };
+  char buf[2];
+  uint8 u8;
+  uint16 u16;
+  uint32 u32;
+  base::StringPiece piece;
+  BigEndianReader reader(data, sizeof(data));
+
+  EXPECT_TRUE(reader.Skip(2));
+  EXPECT_EQ(data + 2, reader.ptr());
+  EXPECT_EQ(reader.remaining(), static_cast<int>(sizeof(data)) - 2);
+  EXPECT_TRUE(reader.ReadBytes(buf, sizeof(buf)));
+  EXPECT_EQ(0x2, buf[0]);
+  EXPECT_EQ(0x3, buf[1]);
+  EXPECT_TRUE(reader.ReadU8(&u8));
+  EXPECT_EQ(0x4, u8);
+  EXPECT_TRUE(reader.ReadU16(&u16));
+  EXPECT_EQ(0x0506, u16);
+  EXPECT_TRUE(reader.ReadU32(&u32));
+  EXPECT_EQ(0x0708090Au, u32);
+  base::StringPiece expected(reader.ptr(), 2);
+  EXPECT_TRUE(reader.ReadPiece(&piece, 2));
+  EXPECT_EQ(2u, piece.size());
+  EXPECT_EQ(expected.data(), piece.data());
+}
+
+TEST(BigEndianReaderTest, RespectsLength) {
+  char data[4];
+  char buf[2];
+  uint8 u8;
+  uint16 u16;
+  uint32 u32;
+  base::StringPiece piece;
+  BigEndianReader reader(data, sizeof(data));
+  // 4 left
+  EXPECT_FALSE(reader.Skip(6));
+  EXPECT_TRUE(reader.Skip(1));
+  // 3 left
+  EXPECT_FALSE(reader.ReadU32(&u32));
+  EXPECT_FALSE(reader.ReadPiece(&piece, 4));
+  EXPECT_TRUE(reader.Skip(2));
+  // 1 left
+  EXPECT_FALSE(reader.ReadU16(&u16));
+  EXPECT_FALSE(reader.ReadBytes(buf, 2));
+  EXPECT_TRUE(reader.Skip(1));
+  // 0 left
+  EXPECT_FALSE(reader.ReadU8(&u8));
+  EXPECT_EQ(0, reader.remaining());
+}
+
+TEST(BigEndianWriterTest, WritesValues) {
+  char expected[] = { 0, 0, 2, 3, 4, 5, 6, 7, 8, 9, 0xA };
+  char data[sizeof(expected)];
+  char buf[] = { 0x2, 0x3 };
+  memset(data, 0, sizeof(data));
+  BigEndianWriter writer(data, sizeof(data));
+
+  EXPECT_TRUE(writer.Skip(2));
+  EXPECT_TRUE(writer.WriteBytes(buf, sizeof(buf)));
+  EXPECT_TRUE(writer.WriteU8(0x4));
+  EXPECT_TRUE(writer.WriteU16(0x0506));
+  EXPECT_TRUE(writer.WriteU32(0x0708090A));
+  EXPECT_EQ(0, memcmp(expected, data, sizeof(expected)));
+}
+
+TEST(BigEndianWriterTest, RespectsLength) {
+  char data[4];
+  char buf[2];
+  uint8 u8 = 0;
+  uint16 u16 = 0;
+  uint32 u32 = 0;
+  BigEndianWriter writer(data, sizeof(data));
+  // 4 left
+  EXPECT_FALSE(writer.Skip(6));
+  EXPECT_TRUE(writer.Skip(1));
+  // 3 left
+  EXPECT_FALSE(writer.WriteU32(u32));
+  EXPECT_TRUE(writer.Skip(2));
+  // 1 left
+  EXPECT_FALSE(writer.WriteU16(u16));
+  EXPECT_FALSE(writer.WriteBytes(buf, 2));
+  EXPECT_TRUE(writer.Skip(1));
+  // 0 left
+  EXPECT_FALSE(writer.WriteU8(u8));
+  EXPECT_EQ(0, writer.remaining());
+}
+
+}  // namespace net
+