Add functions for DER parsing a BIT STRING.

net/der/parser_unittest.cc

 // Copyright 2015 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/logging.h"
 #include "base/numerics/safe_math.h"
 #include "net/der/input.h"
 #include "net/der/parse_values.h"
 #include "net/der/parser.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 178 matching lines @@
   const uint8_t der[] = {0x02, 0x01, 0x01};
   Parser parser((Input(der)));
 
   Input value;
   bool present;
   ASSERT_TRUE(parser.ReadOptionalTag(0x04, &value, &present));
   ASSERT_FALSE(present);
   ASSERT_FALSE(parser.Advance());
 }
 
+// Reads a valid BIT STRING with 1 unused bit.
+TEST(ParserTest, ReadBitString) {
+  const uint8_t der[] = {0x03, 0x03, 0x01, 0xAA, 0xBE};
+  Parser parser((Input(der)));
+
+  Input bytes;
+  uint8_t unused_bits;
+  ASSERT_TRUE(parser.ReadBitString(&bytes, &unused_bits));
+  EXPECT_FALSE(parser.HasMore());
+
+  EXPECT_EQ(1u, unused_bits);
+  ASSERT_EQ(2u, bytes.Length());
+  EXPECT_EQ(0xAA, bytes.UnsafeData()[0]);
+  EXPECT_EQ(0xBE, bytes.UnsafeData()[1]);
+}
+
+// Tries reading a BIT STRING. This should fail because the tag is not for a
+// BIT STRING.
+TEST(ParserTest, ReadBitStringBadTag) {
+  const uint8_t der[] = {0x05, 0x03, 0x01, 0xAA, 0xBE};
+  Parser parser((Input(der)));
+
+  Input bytes;
+  uint8_t unused_bits;
+  EXPECT_FALSE(parser.ReadBitString(&bytes, &unused_bits));
+}
+
+// Reads a BIT STRING with one unused bit using ReadBitStringNoUnusedBits. This
+// should fail because there are unused bits.
+TEST(ParserTest, ReadBitStringNoUnusedBitsFailure) {
+  const uint8_t der[] = {0x03, 0x03, 0x01, 0xAA, 0xBE};
+  Parser parser((Input(der)));
+
+  Input bytes;
+  EXPECT_FALSE(parser.ReadBitStringNoUnusedBits(&bytes));
+}
+
+// Reads a BIT STRING with no unused bits using ReadBitStringNoUnusedBits. This
+// should succeed.
+TEST(ParserTest, ReadBitStringNoUnusedBits) {
+  const uint8_t der[] = {0x03, 0x03, 0x00, 0xAA, 0xBE};
+  Parser parser((Input(der)));
+
+  Input bytes;
+  ASSERT_TRUE(parser.ReadBitStringNoUnusedBits(&bytes));
+  EXPECT_FALSE(parser.HasMore());
+
+  ASSERT_EQ(2u, bytes.Length());
+  EXPECT_EQ(0xAA, bytes.UnsafeData()[0]);
+  EXPECT_EQ(0xBE, bytes.UnsafeData()[1]);
+}
+
 }  // namespace test
 }  // namespace der
 }  // namespace net