Add functions for DER parsing a BIT STRING.

net/der/parser_unittest.cc

Index: net/der/parser_unittest.cc
diff --git a/net/der/parser_unittest.cc b/net/der/parser_unittest.cc
index 1943d6b86ebeb8fa79e1aa5df8147152e30d1681..5bf16216d2e421d69ad57687539137b744c3055f 100644
--- a/net/der/parser_unittest.cc
+++ b/net/der/parser_unittest.cc
@@ -196,6 +196,39 @@ TEST(ParserTest, CannotAdvanceAfterReadOptionalTag) {
   ASSERT_FALSE(parser.Advance());
 }
 
+TEST(ParserTest, ReadBitString) {
+  const uint8_t der[] = {0x03, 0x03, 0x01, 0xAA, 0xBE};
+  Parser parser((Input(der)));

[davidben, 2015/07/27 20:19:59]

[I'm assuming the extra parens here are coming from the Most Vexing Parse.]

[eroman, 2015/07/27 21:19:23]

Correct.
I need those parenthesis to avoid a compile problem :(

/me shakes fist at C++ and its function ptr declarations...

+
+  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]);
+}
+
+TEST(ParserTest, ReadBitString_BadTag) {
+  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 -- should fail.
+TEST(ParserTest, ReadBitStringNoUnusedBits) {
+  const uint8_t der[] = {0x03, 0x03, 0x01, 0xAA, 0xBE};
+  Parser parser((Input(der)));
+
+  Input bytes;
+  EXPECT_FALSE(parser.ReadBitStringNoUnusedBits(&bytes));

[davidben, 2015/07/27 20:19:59]

I dunno if you want a success test for NoUnusedBits.

[eroman, 2015/07/27 21:19:23]

Done.

I also improved the test descriptions.

+}
+
 }  // namespace test
 }  // namespace der
 }  // namespace net