Add functions for DER parsing a BIT STRING.

net/der/parse_values_unittest.cc

Index: net/der/parse_values_unittest.cc
diff --git a/net/der/parse_values_unittest.cc b/net/der/parse_values_unittest.cc
index ea1b5c4e8cca4e28bd85f533fe54b39f05577e50..d27ee0559b36fe4997d76d192e8cc37d1a867d92 100644
--- a/net/der/parse_values_unittest.cc
+++ b/net/der/parse_values_unittest.cc
@@ -195,6 +195,60 @@ TEST(ParseValuesTest, ParseUint64) {
   }
 }
 
+// Tests parsing an empty BIT STRING.
+TEST(ParseValuesTest, ParseBitString_Empty_NoUnusedBits) {

[nharper, 2015/07/21 23:23:47]

Test names shouldn't contain underscores (according to
https://code.google.com/p/googletest/wiki/FAQ#Why_should_not_test_case_names_...,
although I noticed that there are several tests in //net that has underscores in
their names.)

[eroman, 2015/07/22 17:05:23]

Ah, thanks for pointing this out! (I was not aware of that)

Removed all the underscores.

+  const uint8_t kData[] = {0x00};
+
+  Input bytes;
+  uint8_t unused_bits;
+  ASSERT_TRUE(ParseBitString(Input(kData), &bytes, &unused_bits));
+
+  EXPECT_EQ(0u, unused_bits);
+  EXPECT_EQ(0u, bytes.Length());
+}
+
+// Tests parsing an empty BIT STRING that incorrectly claims one unused bit.
+TEST(ParseValuesTest, ParseBitString_Empty_OneUnusedBit) {
+  const uint8_t kData[] = {0x01};
+
+  Input bytes;
+  uint8_t unused_bits;
+  ASSERT_FALSE(ParseBitString(Input(kData), &bytes, &unused_bits));

[nharper, 2015/07/21 23:23:47]

I generally prefer the EXPECT_* macros to ASSERT_* where feasible to allow the
test to continue running. I guess it doesn't really matter when it's the last
line of a test case though.

[eroman, 2015/07/22 17:05:23]

Done.

These are the result of copy-paste from success test cases.
(For which if ParseBitString were to fail, I don't want to proceed as the unused
bit length could be invalid memory).

+}
+
+// Tests parsing an empty BIT STRING that is not minmally encoded (the entire
+// last byte is comprised of unused bits).
+TEST(ParseValuesTest, ParseBitString_NonEmpty_TooManyUnusedBits) {
+  const uint8_t kData[] = {0x08, 0x00};
+
+  Input bytes;
+  uint8_t unused_bits;
+  ASSERT_FALSE(ParseBitString(Input(kData), &bytes, &unused_bits));
+}
+
+// Tests parsing a BIT STRING of 7 bits each of which are 1.
+TEST(ParseValuesTest, ParseBitString_SevenOneBits) {
+  const uint8_t kData[] = {0x01, 0xFE};
+
+  Input bytes;
+  uint8_t unused_bits;
+  ASSERT_TRUE(ParseBitString(Input(kData), &bytes, &unused_bits));
+
+  EXPECT_EQ(1u, unused_bits);
+  EXPECT_EQ(1u, bytes.Length());
+  EXPECT_EQ(0xFE, bytes.UnsafeData()[0]);
+}
+
+// Tests parsing a BIT STRING of 7 bits each of which are 1. The unused bit
+// however is set to 1, which is an invalid encoding.
+TEST(ParseValuesTest, ParseBitString_SevenOneBits_UnusedBitIsOne) {
+  const uint8_t kData[] = {0x01, 0xFF};
+
+  Input bytes;
+  uint8_t unused_bits;
+  ASSERT_FALSE(ParseBitString(Input(kData), &bytes, &unused_bits));
+}
+
 }  // namespace test
 }  // namespace der
 }  // namespace net