text: /* Copyright (c) 2014, Google Inc.
   *
   * Permission to use, copy, modify, and/or distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
   * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
   * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include <vector>
  
  #include <gtest/gtest.h>
  
  #include <openssl/bytestring.h>
  #include <openssl/crypto.h>
  
  #include "internal.h"
  #include "../internal.h"
  #include "../test/test_util.h"
  
  
  TEST(CBSTest, Skip) {
    static const uint8_t kData[] = {1, 2, 3};
    CBS data;
  
    CBS_init(&data, kData, sizeof(kData));
    EXPECT_EQ(3u, CBS_len(&data));
    EXPECT_TRUE(CBS_skip(&data, 1));
    EXPECT_EQ(2u, CBS_len(&data));
    EXPECT_TRUE(CBS_skip(&data, 2));
    EXPECT_EQ(0u, CBS_len(&data));
    EXPECT_FALSE(CBS_skip(&data, 1));
  }
  
  TEST(CBSTest, GetUint) {
    static const uint8_t kData[] = {1,  2,  3,  4,  5,  6,  7,  8,  9,  10,
                                    11, 12, 13, 14, 15, 16, 17, 18, 19, 20};
    uint8_t u8;
    uint16_t u16;
    uint32_t u32;
    uint64_t u64;
    CBS data;
  
    CBS_init(&data, kData, sizeof(kData));
    ASSERT_TRUE(CBS_get_u8(&data, &u8));
    EXPECT_EQ(1u, u8);
    ASSERT_TRUE(CBS_get_u16(&data, &u16));
    EXPECT_EQ(0x203u, u16);
    ASSERT_TRUE(CBS_get_u24(&data, &u32));
    EXPECT_EQ(0x40506u, u32);
    ASSERT_TRUE(CBS_get_u32(&data, &u32));
    EXPECT_EQ(0x708090au, u32);
    ASSERT_TRUE(CBS_get_u64(&data, &u64));
    EXPECT_EQ(0xb0c0d0e0f101112u, u64);
    ASSERT_TRUE(CBS_get_last_u8(&data, &u8));
    EXPECT_EQ(0x14u, u8);
    ASSERT_TRUE(CBS_get_last_u8(&data, &u8));
    EXPECT_EQ(0x13u, u8);
    EXPECT_FALSE(CBS_get_u8(&data, &u8));
    EXPECT_FALSE(CBS_get_last_u8(&data, &u8));
  
    CBS_init(&data, kData, sizeof(kData));
    ASSERT_TRUE(CBS_get_u16le(&data, &u16));
    EXPECT_EQ(0x0201u, u16);
    ASSERT_TRUE(CBS_get_u32le(&data, &u32));
    EXPECT_EQ(0x06050403u, u32);
    ASSERT_TRUE(CBS_get_u64le(&data, &u64));
    EXPECT_EQ(0x0e0d0c0b0a090807u, u64);
  }
  
  TEST(CBSTest, GetPrefixed) {
    static const uint8_t kData[] = {1, 2, 0, 2, 3, 4, 0, 0, 3, 3, 2, 1};
    uint8_t u8;
    uint16_t u16;
    uint32_t u32;
    CBS data, prefixed;
  
    CBS_init(&data, kData, sizeof(kData));
    ASSERT_TRUE(CBS_get_u8_length_prefixed(&data, &prefixed));
    EXPECT_EQ(1u, CBS_len(&prefixed));
    ASSERT_TRUE(CBS_get_u8(&prefixed, &u8));
    EXPECT_EQ(2u, u8);
    ASSERT_TRUE(CBS_get_u16_length_prefixed(&data, &prefixed));
    EXPECT_EQ(2u, CBS_len(&prefixed));
    ASSERT_TRUE(CBS_get_u16(&prefixed, &u16));
    EXPECT_EQ(0x304u, u16);
    ASSERT_TRUE(CBS_get_u24_length_prefixed(&data, &prefixed));
    EXPECT_EQ(3u, CBS_len(&prefixed));
    ASSERT_TRUE(CBS_get_u24(&prefixed, &u32));
    EXPECT_EQ(0x30201u, u32);
  }
  
  TEST(CBSTest, GetPrefixedBad) {
    static const uint8_t kData1[] = {2, 1};
    static const uint8_t kData2[] = {0, 2, 1};
    static const uint8_t kData3[] = {0, 0, 2, 1};
    CBS data, prefixed;
  
    CBS_init(&data, kData1, sizeof(kData1));
    EXPECT_FALSE(CBS_get_u8_length_prefixed(&data, &prefixed));
  
    CBS_init(&data, kData2, sizeof(kData2));
    EXPECT_FALSE(CBS_get_u16_length_prefixed(&data, &prefixed));
  
    CBS_init(&data, kData3, sizeof(kData3));
    EXPECT_FALSE(CBS_get_u24_length_prefixed(&data, &prefixed));
  }
  
  TEST(CBSTest, GetASN1) {
    static const uint8_t kData1[] = {0x30, 2, 1, 2};
    static const uint8_t kData2[] = {0x30, 3, 1, 2};
    static const uint8_t kData3[] = {0x30, 0x80};
    static const uint8_t kData4[] = {0x30, 0x81, 1, 1};
    static const uint8_t kData5[4 + 0x80] = {0x30, 0x82, 0, 0x80};
    static const uint8_t kData6[] = {0xa1, 3, 0x4, 1, 1};
    static const uint8_t kData7[] = {0xa1, 3, 0x4, 2, 1};
    static const uint8_t kData8[] = {0xa1, 3, 0x2, 1, 1};
    static const uint8_t kData9[] = {0xa1, 3, 0x2, 1, 0xff};
  
    CBS data, contents;
    int present;
    uint64_t value;
  
    CBS_init(&data, kData1, sizeof(kData1));
    EXPECT_FALSE(CBS_peek_asn1_tag(&data, CBS_ASN1_BOOLEAN));
    EXPECT_TRUE(CBS_peek_asn1_tag(&data, CBS_ASN1_SEQUENCE));
  
    ASSERT_TRUE(CBS_get_asn1(&data, &contents, CBS_ASN1_SEQUENCE));
    EXPECT_EQ(Bytes("\x01\x02"), Bytes(CBS_data(&contents), CBS_len(&contents)));
  
    CBS_init(&data, kData2, sizeof(kData2));
    // data is truncated
    EXPECT_FALSE(CBS_get_asn1(&data, &contents, CBS_ASN1_SEQUENCE));
  
    CBS_init(&data, kData3, sizeof(kData3));
    // zero byte length of length
    EXPECT_FALSE(CBS_get_asn1(&data, &contents, CBS_ASN1_SEQUENCE));
  
    CBS_init(&data, kData4, sizeof(kData4));
    // long form mistakenly used.
    EXPECT_FALSE(CBS_get_asn1(&data, &contents, CBS_ASN1_SEQUENCE));
  
    CBS_init(&data, kData5, sizeof(kData5));
    // length takes too many bytes.
    EXPECT_FALSE(CBS_get_asn1(&data, &contents, CBS_ASN1_SEQUENCE));
  
    CBS_init(&data, kData1, sizeof(kData1));
    // wrong tag.
    EXPECT_FALSE(CBS_get_asn1(&data, &contents, 0x31));
  
    CBS_init(&data, NULL, 0);
    // peek at empty data.
    EXPECT_FALSE(CBS_peek_asn1_tag(&data, CBS_ASN1_SEQUENCE));
  
    CBS_init(&data, NULL, 0);
    // optional elements at empty data.
    ASSERT_TRUE(CBS_get_optional_asn1(
        &data, &contents, &present,
        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0));
    EXPECT_FALSE(present);
    ASSERT_TRUE(CBS_get_optional_asn1_octet_string(
        &data, &contents, &present,
        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0));
    EXPECT_FALSE(present);
    EXPECT_EQ(0u, CBS_len(&contents));
    ASSERT_TRUE(CBS_get_optional_asn1_octet_string(
        &data, &contents, NULL,
        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0));
    EXPECT_EQ(0u, CBS_len(&contents));
    ASSERT_TRUE(CBS_get_optional_asn1_uint64(
        &data, &value, CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0, 42));
    EXPECT_EQ(42u, value);
  
    CBS_init(&data, kData6, sizeof(kData6));
    // optional element.
    ASSERT_TRUE(CBS_get_optional_asn1(
        &data, &contents, &present,
        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0));
    EXPECT_FALSE(present);
    ASSERT_TRUE(CBS_get_optional_asn1(
        &data, &contents, &present,
        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1));
    EXPECT_TRUE(present);
    EXPECT_EQ(Bytes("\x04\x01\x01"),
              Bytes(CBS_data(&contents), CBS_len(&contents)));
  
    CBS_init(&data, kData6, sizeof(kData6));
    // optional octet string.
    ASSERT_TRUE(CBS_get_optional_asn1_octet_string(
        &data, &contents, &present,
        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0));
    EXPECT_FALSE(present);
    EXPECT_EQ(0u, CBS_len(&contents));
    ASSERT_TRUE(CBS_get_optional_asn1_octet_string(
        &data, &contents, &present,
        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1));
    EXPECT_TRUE(present);
    EXPECT_EQ(Bytes("\x01"), Bytes(CBS_data(&contents), CBS_len(&contents)));
  
    CBS_init(&data, kData7, sizeof(kData7));
    // invalid optional octet string.
    EXPECT_FALSE(CBS_get_optional_asn1_octet_string(
        &data, &contents, &present,
        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1));
  
    CBS_init(&data, kData8, sizeof(kData8));
    // optional integer.
    ASSERT_TRUE(CBS_get_optional_asn1_uint64(
        &data, &value, CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0, 42));
    EXPECT_EQ(42u, value);
    ASSERT_TRUE(CBS_get_optional_asn1_uint64(
        &data, &value, CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1, 42));
    EXPECT_EQ(1u, value);
  
    CBS_init(&data, kData9, sizeof(kData9));
    // invalid optional integer.
    EXPECT_FALSE(CBS_get_optional_asn1_uint64(
        &data, &value, CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1, 42));
  
    unsigned tag;
    CBS_init(&data, kData1, sizeof(kData1));
    ASSERT_TRUE(CBS_get_any_asn1(&data, &contents, &tag));
    EXPECT_EQ(CBS_ASN1_SEQUENCE, tag);
    EXPECT_EQ(Bytes("\x01\x02"), Bytes(CBS_data(&contents), CBS_len(&contents)));
  
    size_t header_len;
    CBS_init(&data, kData1, sizeof(kData1));
    ASSERT_TRUE(CBS_get_any_asn1_element(&data, &contents, &tag, &header_len));
    EXPECT_EQ(CBS_ASN1_SEQUENCE, tag);
    EXPECT_EQ(2u, header_len);
    EXPECT_EQ(Bytes("\x30\x02\x01\x02"),
              Bytes(CBS_data(&contents), CBS_len(&contents)));
  }
  
  TEST(CBSTest, ParseASN1Tag) {
    const struct {
      bool ok;
      unsigned tag;
      std::vector<uint8_t> in;
    } kTests[] = {
        {true, CBS_ASN1_SEQUENCE, {0x30, 0}},
        {true, CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 4, {0xa4, 0}},
        {true, CBS_ASN1_APPLICATION | 30, {0x5e, 0}},
        {true, CBS_ASN1_APPLICATION | 31, {0x5f, 0x1f, 0}},
        {true, CBS_ASN1_APPLICATION | 32, {0x5f, 0x20, 0}},
        {true,
         CBS_ASN1_PRIVATE | CBS_ASN1_CONSTRUCTED | 0x1fffffff,
         {0xff, 0x81, 0xff, 0xff, 0xff, 0x7f, 0}},
        // Tag number fits in unsigned but not |CBS_ASN1_TAG_NUMBER_MASK|.
        {false, 0, {0xff, 0x82, 0xff, 0xff, 0xff, 0x7f, 0}},
        // Tag number does not fit in unsigned.
        {false, 0, {0xff, 0x90, 0x80, 0x80, 0x80, 0, 0}},
        // Tag number is not minimally-encoded
        {false, 0, {0x5f, 0x80, 0x1f, 0}},
        // Tag number should have used short form.
        {false, 0, {0x5f, 0x80, 0x1e, 0}},
    };
    for (const auto &t : kTests) {
      SCOPED_TRACE(Bytes(t.in));
      unsigned tag;
      CBS cbs, child;
      CBS_init(&cbs, t.in.data(), t.in.size());
      ASSERT_EQ(t.ok, !!CBS_get_any_asn1(&cbs, &child, &tag));
      if (t.ok) {
        EXPECT_EQ(t.tag, tag);
        EXPECT_EQ(0u, CBS_len(&child));
        EXPECT_EQ(0u, CBS_len(&cbs));
  
        CBS_init(&cbs, t.in.data(), t.in.size());
        EXPECT_TRUE(CBS_peek_asn1_tag(&cbs, t.tag));
        EXPECT_FALSE(CBS_peek_asn1_tag(&cbs, t.tag + 1));
  
        EXPECT_TRUE(CBS_get_asn1(&cbs, &child, t.tag));
        EXPECT_EQ(0u, CBS_len(&child));
        EXPECT_EQ(0u, CBS_len(&cbs));
  
        CBS_init(&cbs, t.in.data(), t.in.size());
        EXPECT_FALSE(CBS_get_asn1(&cbs, &child, t.tag + 1));
      }
    }
  }
  
  TEST(CBSTest, GetOptionalASN1Bool) {
    static const uint8_t kTrue[] = {0x0a, 3, CBS_ASN1_BOOLEAN, 1, 0xff};
    static const uint8_t kFalse[] = {0x0a, 3, CBS_ASN1_BOOLEAN, 1, 0x00};
    static const uint8_t kInvalid[] = {0x0a, 3, CBS_ASN1_BOOLEAN, 1, 0x01};
  
    CBS data;
    CBS_init(&data, NULL, 0);
    int val = 2;
    ASSERT_TRUE(CBS_get_optional_asn1_bool(&data, &val, 0x0a, 0));
    EXPECT_EQ(0, val);
  
    CBS_init(&data, kTrue, sizeof(kTrue));
    val = 2;
    ASSERT_TRUE(CBS_get_optional_asn1_bool(&data, &val, 0x0a, 0));
    EXPECT_EQ(1, val);
  
    CBS_init(&data, kFalse, sizeof(kFalse));
    val = 2;
    ASSERT_TRUE(CBS_get_optional_asn1_bool(&data, &val, 0x0a, 1));
    EXPECT_EQ(0, val);
  
    CBS_init(&data, kInvalid, sizeof(kInvalid));
    EXPECT_FALSE(CBS_get_optional_asn1_bool(&data, &val, 0x0a, 1));
  }
  
  // Test that CBB_init may be used on an uninitialized input.
  TEST(CBBTest, InitUninitialized) {
    CBB cbb;
    ASSERT_TRUE(CBB_init(&cbb, 100));
    CBB_cleanup(&cbb);
  }
  
  TEST(CBBTest, Basic) {
    static const uint8_t kExpected[] = {1,   2,    3,    4,    5,    6,   7,
                                        8,   9,    0xa,  0xb,  0xc,  0xd, 0xe,
                                        0xf, 0x10, 0x11, 0x12, 0x13, 0x14, 3, 2,
                                        10,  9,    8,    7,    0x12, 0x11, 0x10,
                                        0xf, 0xe,  0xd,  0xc,  0xb};
    uint8_t *buf;
    size_t buf_len;
  
    bssl::ScopedCBB cbb;
    ASSERT_TRUE(CBB_init(cbb.get(), 100));
    cbb.Reset();
  
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_TRUE(CBB_add_u8(cbb.get(), 1));
    ASSERT_TRUE(CBB_add_u16(cbb.get(), 0x203));
    ASSERT_TRUE(CBB_add_u24(cbb.get(), 0x40506));
    ASSERT_TRUE(CBB_add_u32(cbb.get(), 0x708090a));
    ASSERT_TRUE(CBB_add_u64(cbb.get(), 0xb0c0d0e0f101112));
    ASSERT_TRUE(CBB_add_bytes(cbb.get(), (const uint8_t *)"\x13\x14", 2));
    ASSERT_TRUE(CBB_add_u16le(cbb.get(), 0x203));
    ASSERT_TRUE(CBB_add_u32le(cbb.get(), 0x708090a));
    ASSERT_TRUE(CBB_add_u64le(cbb.get(), 0xb0c0d0e0f101112));
    ASSERT_TRUE(CBB_finish(cbb.get(), &buf, &buf_len));
  
    bssl::UniquePtr<uint8_t> scoper(buf);
    EXPECT_EQ(Bytes(kExpected), Bytes(buf, buf_len));
  }
  
  TEST(CBBTest, Fixed) {
    bssl::ScopedCBB cbb;
    uint8_t buf[1];
    uint8_t *out_buf;
    size_t out_size;
  
    ASSERT_TRUE(CBB_init_fixed(cbb.get(), NULL, 0));
    ASSERT_TRUE(CBB_finish(cbb.get(), &out_buf, &out_size));
    EXPECT_EQ(NULL, out_buf);
    EXPECT_EQ(0u, out_size);
  
    cbb.Reset();
    ASSERT_TRUE(CBB_init_fixed(cbb.get(), buf, 1));
    ASSERT_TRUE(CBB_add_u8(cbb.get(), 1));
    ASSERT_TRUE(CBB_finish(cbb.get(), &out_buf, &out_size));
    EXPECT_EQ(buf, out_buf);
    EXPECT_EQ(1u, out_size);
    EXPECT_EQ(1u, buf[0]);
  
    cbb.Reset();
    ASSERT_TRUE(CBB_init_fixed(cbb.get(), buf, 1));
    ASSERT_TRUE(CBB_add_u8(cbb.get(), 1));
    EXPECT_FALSE(CBB_add_u8(cbb.get(), 2));
  }
  
  // Test that calling CBB_finish on a child does nothing.
  TEST(CBBTest, FinishChild) {
    CBB child;
    uint8_t *out_buf;
    size_t out_size;
  
    bssl::ScopedCBB cbb;
    ASSERT_TRUE(CBB_init(cbb.get(), 16));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &child));
  
    EXPECT_FALSE(CBB_finish(&child, &out_buf, &out_size));
  
    ASSERT_TRUE(CBB_finish(cbb.get(), &out_buf, &out_size));
    bssl::UniquePtr<uint8_t> scoper(out_buf);
    ASSERT_EQ(1u, out_size);
    EXPECT_EQ(0u, out_buf[0]);
  }
  
  TEST(CBBTest, Prefixed) {
    static const uint8_t kExpected[] = {0, 1, 1, 0, 2, 2, 3, 0, 0, 3,
                                        4, 5, 6, 5, 4, 1, 0, 1, 2};
    uint8_t *buf;
    size_t buf_len;
    bssl::ScopedCBB cbb;
    CBB contents, inner_contents, inner_inner_contents;
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    EXPECT_EQ(0u, CBB_len(cbb.get()));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u8(&contents, 1));
    EXPECT_EQ(1u, CBB_len(&contents));
    ASSERT_TRUE(CBB_flush(cbb.get()));
    EXPECT_EQ(3u, CBB_len(cbb.get()));
    ASSERT_TRUE(CBB_add_u16_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u16(&contents, 0x203));
    ASSERT_TRUE(CBB_add_u24_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u24(&contents, 0x40506));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(&contents, &inner_contents));
    ASSERT_TRUE(CBB_add_u8(&inner_contents, 1));
    ASSERT_TRUE(
        CBB_add_u16_length_prefixed(&inner_contents, &inner_inner_contents));
    ASSERT_TRUE(CBB_add_u8(&inner_inner_contents, 2));
    ASSERT_TRUE(CBB_finish(cbb.get(), &buf, &buf_len));
  
    bssl::UniquePtr<uint8_t> scoper(buf);
    EXPECT_EQ(Bytes(kExpected), Bytes(buf, buf_len));
  }
  
  TEST(CBBTest, DiscardChild) {
    bssl::ScopedCBB cbb;
    CBB contents, inner_contents, inner_inner_contents;
  
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_TRUE(CBB_add_u8(cbb.get(), 0xaa));
  
    // Discarding |cbb|'s children preserves the byte written.
    CBB_discard_child(cbb.get());
  
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u8(&contents, 0xbb));
    ASSERT_TRUE(CBB_add_u16_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u16(&contents, 0xcccc));
    ASSERT_TRUE(CBB_add_u24_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u24(&contents, 0xdddddd));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &contents));
    ASSERT_TRUE(CBB_add_u8(&contents, 0xff));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(&contents, &inner_contents));
    ASSERT_TRUE(CBB_add_u8(&inner_contents, 0x42));
    ASSERT_TRUE(
        CBB_add_u16_length_prefixed(&inner_contents, &inner_inner_contents));
    ASSERT_TRUE(CBB_add_u8(&inner_inner_contents, 0x99));
  
    // Discard everything from |inner_contents| down.
    CBB_discard_child(&contents);
  
    uint8_t *buf;
    size_t buf_len;
    ASSERT_TRUE(CBB_finish(cbb.get(), &buf, &buf_len));
    bssl::UniquePtr<uint8_t> scoper(buf);
  
    static const uint8_t kExpected[] = {
          0xaa,
          0,
          1, 0xbb,
          0, 2, 0xcc, 0xcc,
          0, 0, 3, 0xdd, 0xdd, 0xdd,
          1, 0xff,
    };
    EXPECT_EQ(Bytes(kExpected), Bytes(buf, buf_len));
  }
  
  TEST(CBBTest, Misuse) {
    bssl::ScopedCBB cbb;
    CBB child, contents;
    uint8_t *buf;
    size_t buf_len;
  
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &child));
    ASSERT_TRUE(CBB_add_u8(&child, 1));
    ASSERT_TRUE(CBB_add_u8(cbb.get(), 2));
  
    // Since we wrote to |cbb|, |child| is now invalid and attempts to write to
    // it should fail.
    EXPECT_FALSE(CBB_add_u8(&child, 1));
    EXPECT_FALSE(CBB_add_u16(&child, 1));
    EXPECT_FALSE(CBB_add_u24(&child, 1));
    EXPECT_FALSE(CBB_add_u8_length_prefixed(&child, &contents));
    EXPECT_FALSE(CBB_add_u16_length_prefixed(&child, &contents));
    EXPECT_FALSE(CBB_add_asn1(&child, &contents, 1));
    EXPECT_FALSE(CBB_add_bytes(&child, (const uint8_t*) "a", 1));
  
    ASSERT_TRUE(CBB_finish(cbb.get(), &buf, &buf_len));
    bssl::UniquePtr<uint8_t> scoper(buf);
  
    EXPECT_EQ(Bytes("\x01\x01\x02"), Bytes(buf, buf_len));
  }
  
  TEST(CBBTest, ASN1) {
    static const uint8_t kExpected[] = {
        // SEQUENCE { 1 2 3 }
        0x30, 3, 1, 2, 3,
        // [4 CONSTRUCTED] { 4 5 6 }
        0xa4, 3, 4, 5, 6,
        // [APPLICATION 30 PRIMITIVE] { 7 8 9 }
        0x5e, 3, 7, 8, 9,
        // [APPLICATION 31 PRIMITIVE] { 10 11 12 }
        0x5f, 0x1f, 3, 10, 11, 12,
        // [PRIVATE 2^29-1 CONSTRUCTED] { 13 14 15 }
        0xff, 0x81, 0xff, 0xff, 0xff, 0x7f, 3, 13, 14, 15,
    };
    uint8_t *buf;
    size_t buf_len;
    bssl::ScopedCBB cbb;
    CBB contents, inner_contents;
  
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_TRUE(CBB_add_asn1(cbb.get(), &contents, CBS_ASN1_SEQUENCE));
    ASSERT_TRUE(CBB_add_bytes(&contents, (const uint8_t *)"\x01\x02\x03", 3));
    ASSERT_TRUE(
        CBB_add_asn1(cbb.get(), &contents,
                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 4));
    ASSERT_TRUE(CBB_add_bytes(&contents, (const uint8_t *)"\x04\x05\x06", 3));
    ASSERT_TRUE(
        CBB_add_asn1(cbb.get(), &contents,
                     CBS_ASN1_APPLICATION | 30));
    ASSERT_TRUE(CBB_add_bytes(&contents, (const uint8_t *)"\x07\x08\x09", 3));
    ASSERT_TRUE(
        CBB_add_asn1(cbb.get(), &contents,
                     CBS_ASN1_APPLICATION | 31));
    ASSERT_TRUE(CBB_add_bytes(&contents, (const uint8_t *)"\x0a\x0b\x0c", 3));
    ASSERT_TRUE(
        CBB_add_asn1(cbb.get(), &contents,
                     CBS_ASN1_PRIVATE | CBS_ASN1_CONSTRUCTED | 0x1fffffff));
    ASSERT_TRUE(CBB_add_bytes(&contents, (const uint8_t *)"\x0d\x0e\x0f", 3));
    ASSERT_TRUE(CBB_finish(cbb.get(), &buf, &buf_len));
    bssl::UniquePtr<uint8_t> scoper(buf);
  
    EXPECT_EQ(Bytes(kExpected), Bytes(buf, buf_len));
  
    std::vector<uint8_t> test_data(100000, 0x42);
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_TRUE(CBB_add_asn1(cbb.get(), &contents, CBS_ASN1_SEQUENCE));
    ASSERT_TRUE(CBB_add_bytes(&contents, test_data.data(), 130));
    ASSERT_TRUE(CBB_finish(cbb.get(), &buf, &buf_len));
    scoper.reset(buf);
  
    ASSERT_EQ(3u + 130u, buf_len);
    EXPECT_EQ(Bytes("\x30\x81\x82"), Bytes(buf, 3));
    EXPECT_EQ(Bytes(test_data.data(), 130), Bytes(buf + 3, 130));
  
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_TRUE(CBB_add_asn1(cbb.get(), &contents, CBS_ASN1_SEQUENCE));
    ASSERT_TRUE(CBB_add_bytes(&contents, test_data.data(), 1000));
    ASSERT_TRUE(CBB_finish(cbb.get(), &buf, &buf_len));
    scoper.reset(buf);
  
    ASSERT_EQ(4u + 1000u, buf_len);
    EXPECT_EQ(Bytes("\x30\x82\x03\xe8"), Bytes(buf, 4));
    EXPECT_EQ(Bytes(test_data.data(), 1000), Bytes(buf + 4, 1000));
  
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_TRUE(CBB_add_asn1(cbb.get(), &contents, CBS_ASN1_SEQUENCE));
    ASSERT_TRUE(CBB_add_asn1(&contents, &inner_contents, CBS_ASN1_SEQUENCE));
    ASSERT_TRUE(CBB_add_bytes(&inner_contents, test_data.data(), 100000));
    ASSERT_TRUE(CBB_finish(cbb.get(), &buf, &buf_len));
    scoper.reset(buf);
  
    ASSERT_EQ(5u + 5u + 100000u, buf_len);
    EXPECT_EQ(Bytes("\x30\x83\x01\x86\xa5\x30\x83\x01\x86\xa0"), Bytes(buf, 10));
    EXPECT_EQ(Bytes(test_data.data(), test_data.size()), Bytes(buf + 10, 100000));
  }
  
  static void ExpectBerConvert(const char *name, const uint8_t *der_expected,
                               size_t der_len, const uint8_t *ber,
                               size_t ber_len) {
    SCOPED_TRACE(name);
    CBS in, out;
    uint8_t *storage;
  
    CBS_init(&in, ber, ber_len);
    ASSERT_TRUE(CBS_asn1_ber_to_der(&in, &out, &storage));
    bssl::UniquePtr<uint8_t> scoper(storage);
  
    EXPECT_EQ(Bytes(der_expected, der_len), Bytes(CBS_data(&out), CBS_len(&out)));
    if (storage != nullptr) {
      EXPECT_NE(Bytes(der_expected, der_len), Bytes(ber, ber_len));
    } else {
      EXPECT_EQ(Bytes(der_expected, der_len), Bytes(ber, ber_len));
    }
  }
  
  TEST(CBSTest, BerConvert) {
    static const uint8_t kSimpleBER[] = {0x01, 0x01, 0x00};
  
    // kIndefBER contains a SEQUENCE with an indefinite length.
    static const uint8_t kIndefBER[] = {0x30, 0x80, 0x01, 0x01, 0x02, 0x00, 0x00};
    static const uint8_t kIndefDER[] = {0x30, 0x03, 0x01, 0x01, 0x02};
  
    // kIndefBER2 contains a constructed [APPLICATION 31] with an indefinite
    // length.
    static const uint8_t kIndefBER2[] = {0x7f, 0x1f, 0x80, 0x01,
                                         0x01, 0x02, 0x00, 0x00};
    static const uint8_t kIndefDER2[] = {0x7f, 0x1f, 0x03, 0x01, 0x01, 0x02};
  
    // kOctetStringBER contains an indefinite length OCTET STRING with two parts.
    // These parts need to be concatenated in DER form.
    static const uint8_t kOctetStringBER[] = {0x24, 0x80, 0x04, 0x02, 0,    1,
                                              0x04, 0x02, 2,    3,    0x00, 0x00};
    static const uint8_t kOctetStringDER[] = {0x04, 0x04, 0, 1, 2, 3};
  
    // kNSSBER is part of a PKCS#12 message generated by NSS that uses indefinite
    // length elements extensively.
    static const uint8_t kNSSBER[] = {
        0x30, 0x80, 0x02, 0x01, 0x03, 0x30, 0x80, 0x06, 0x09, 0x2a, 0x86, 0x48,
        0x86, 0xf7, 0x0d, 0x01, 0x07, 0x01, 0xa0, 0x80, 0x24, 0x80, 0x04, 0x04,
        0x01, 0x02, 0x03, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 0x39,
        0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a, 0x05,
        0x00, 0x04, 0x14, 0x84, 0x98, 0xfc, 0x66, 0x33, 0xee, 0xba, 0xe7, 0x90,
        0xc1, 0xb6, 0xe8, 0x8f, 0xfe, 0x1d, 0xc5, 0xa5, 0x97, 0x93, 0x3e, 0x04,
        0x10, 0x38, 0x62, 0xc6, 0x44, 0x12, 0xd5, 0x30, 0x00, 0xf8, 0xf2, 0x1b,
        0xf0, 0x6e, 0x10, 0x9b, 0xb8, 0x02, 0x02, 0x07, 0xd0, 0x00, 0x00,
    };
  
    static const uint8_t kNSSDER[] = {
        0x30, 0x53, 0x02, 0x01, 0x03, 0x30, 0x13, 0x06, 0x09, 0x2a, 0x86,
        0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07, 0x01, 0xa0, 0x06, 0x04, 0x04,
        0x01, 0x02, 0x03, 0x04, 0x30, 0x39, 0x30, 0x21, 0x30, 0x09, 0x06,
        0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a, 0x05, 0x00, 0x04, 0x14, 0x84,
        0x98, 0xfc, 0x66, 0x33, 0xee, 0xba, 0xe7, 0x90, 0xc1, 0xb6, 0xe8,
        0x8f, 0xfe, 0x1d, 0xc5, 0xa5, 0x97, 0x93, 0x3e, 0x04, 0x10, 0x38,
        0x62, 0xc6, 0x44, 0x12, 0xd5, 0x30, 0x00, 0xf8, 0xf2, 0x1b, 0xf0,
        0x6e, 0x10, 0x9b, 0xb8, 0x02, 0x02, 0x07, 0xd0,
    };
  
    // kConstructedStringBER contains a deeply-nested constructed OCTET STRING.
    // The BER conversion collapses this to one level deep, but not completely.
    static const uint8_t kConstructedStringBER[] = {
        0xa0, 0x10, 0x24, 0x06, 0x04, 0x01, 0x00, 0x04, 0x01,
        0x01, 0x24, 0x06, 0x04, 0x01, 0x02, 0x04, 0x01, 0x03,
    };
    static const uint8_t kConstructedStringDER[] = {
        0xa0, 0x08, 0x04, 0x02, 0x00, 0x01, 0x04, 0x02, 0x02, 0x03,
    };
  
    ExpectBerConvert("kSimpleBER", kSimpleBER, sizeof(kSimpleBER), kSimpleBER,
                     sizeof(kSimpleBER));
    ExpectBerConvert("kIndefBER", kIndefDER, sizeof(kIndefDER), kIndefBER,
                     sizeof(kIndefBER));
    ExpectBerConvert("kIndefBER2", kIndefDER2, sizeof(kIndefDER2), kIndefBER2,
                     sizeof(kIndefBER2));
    ExpectBerConvert("kOctetStringBER", kOctetStringDER, sizeof(kOctetStringDER),
                     kOctetStringBER, sizeof(kOctetStringBER));
    ExpectBerConvert("kNSSBER", kNSSDER, sizeof(kNSSDER), kNSSBER,
                     sizeof(kNSSBER));
    ExpectBerConvert("kConstructedStringBER", kConstructedStringDER,
                     sizeof(kConstructedStringDER), kConstructedStringBER,
                     sizeof(kConstructedStringBER));
  }
  
  struct ImplicitStringTest {
    const char *in;
    size_t in_len;
    bool ok;
    const char *out;
    size_t out_len;
  };
  
  static const ImplicitStringTest kImplicitStringTests[] = {
      // A properly-encoded string.
      {"\x80\x03\x61\x61\x61", 5, true, "aaa", 3},
      // An implicit-tagged string.
      {"\xa0\x09\x04\x01\x61\x04\x01\x61\x04\x01\x61", 11, true, "aaa", 3},
      // |CBS_get_asn1_implicit_string| only accepts one level deep of nesting.
      {"\xa0\x0b\x24\x06\x04\x01\x61\x04\x01\x61\x04\x01\x61", 13, false, nullptr,
       0},
      // The outer tag must match.
      {"\x81\x03\x61\x61\x61", 5, false, nullptr, 0},
      {"\xa1\x09\x04\x01\x61\x04\x01\x61\x04\x01\x61", 11, false, nullptr, 0},
      // The inner tag must match.
      {"\xa1\x09\x0c\x01\x61\x0c\x01\x61\x0c\x01\x61", 11, false, nullptr, 0},
  };
  
  TEST(CBSTest, ImplicitString) {
    for (const auto &test : kImplicitStringTests) {
      SCOPED_TRACE(Bytes(test.in, test.in_len));
      uint8_t *storage = nullptr;
      CBS in, out;
      CBS_init(&in, reinterpret_cast<const uint8_t *>(test.in), test.in_len);
      int ok = CBS_get_asn1_implicit_string(&in, &out, &storage,
                                            CBS_ASN1_CONTEXT_SPECIFIC | 0,
                                            CBS_ASN1_OCTETSTRING);
      bssl::UniquePtr<uint8_t> scoper(storage);
      EXPECT_EQ(test.ok, static_cast<bool>(ok));
  
      if (ok) {
        EXPECT_EQ(Bytes(test.out, test.out_len),
                  Bytes(CBS_data(&out), CBS_len(&out)));
      }
    }
  }
  
  struct ASN1Uint64Test {
    uint64_t value;
    const char *encoding;
    size_t encoding_len;
  };
  
  static const ASN1Uint64Test kASN1Uint64Tests[] = {
      {0, "\x02\x01\x00", 3},
      {1, "\x02\x01\x01", 3},
      {127, "\x02\x01\x7f", 3},
      {128, "\x02\x02\x00\x80", 4},
      {0xdeadbeef, "\x02\x05\x00\xde\xad\xbe\xef", 7},
      {UINT64_C(0x0102030405060708),
       "\x02\x08\x01\x02\x03\x04\x05\x06\x07\x08", 10},
      {UINT64_C(0xffffffffffffffff),
        "\x02\x09\x00\xff\xff\xff\xff\xff\xff\xff\xff", 11},
  };
  
  struct ASN1InvalidUint64Test {
    const char *encoding;
    size_t encoding_len;
  };
  
  static const ASN1InvalidUint64Test kASN1InvalidUint64Tests[] = {
      // Bad tag.
      {"\x03\x01\x00", 3},
      // Empty contents.
      {"\x02\x00", 2},
      // Negative number.
      {"\x02\x01\x80", 3},
      // Overflow.
      {"\x02\x09\x01\x00\x00\x00\x00\x00\x00\x00\x00", 11},
      // Leading zeros.
      {"\x02\x02\x00\x01", 4},
  };
  
  TEST(CBSTest, ASN1Uint64) {
    for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(kASN1Uint64Tests); i++) {
      SCOPED_TRACE(i);
      const ASN1Uint64Test *test = &kASN1Uint64Tests[i];
      CBS cbs;
      uint64_t value;
      uint8_t *out;
      size_t len;
  
      CBS_init(&cbs, (const uint8_t *)test->encoding, test->encoding_len);
      ASSERT_TRUE(CBS_get_asn1_uint64(&cbs, &value));
      EXPECT_EQ(0u, CBS_len(&cbs));
      EXPECT_EQ(test->value, value);
  
      bssl::ScopedCBB cbb;
      ASSERT_TRUE(CBB_init(cbb.get(), 0));
      ASSERT_TRUE(CBB_add_asn1_uint64(cbb.get(), test->value));
      ASSERT_TRUE(CBB_finish(cbb.get(), &out, &len));
      bssl::UniquePtr<uint8_t> scoper(out);
      EXPECT_EQ(Bytes(test->encoding, test->encoding_len), Bytes(out, len));
    }
  
    for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(kASN1InvalidUint64Tests); i++) {
      const ASN1InvalidUint64Test *test = &kASN1InvalidUint64Tests[i];
      CBS cbs;
      uint64_t value;
  
      CBS_init(&cbs, (const uint8_t *)test->encoding, test->encoding_len);
      EXPECT_FALSE(CBS_get_asn1_uint64(&cbs, &value));
    }
  }
  
  struct ASN1Int64Test {
    int64_t value;
    const char *encoding;
    size_t encoding_len;
  };
  
  static const ASN1Int64Test kASN1Int64Tests[] = {
      {0, "\x02\x01\x00", 3},
      {1, "\x02\x01\x01", 3},
      {-1, "\x02\x01\xff", 3},
      {127, "\x02\x01\x7f", 3},
      {-127, "\x02\x01\x81", 3},
      {128, "\x02\x02\x00\x80", 4},
      {-128, "\x02\x01\x80", 3},
      {129, "\x02\x02\x00\x81", 4},
      {-129, "\x02\x02\xff\x7f", 4},
      {0xdeadbeef, "\x02\x05\x00\xde\xad\xbe\xef", 7},
      {INT64_C(0x0102030405060708), "\x02\x08\x01\x02\x03\x04\x05\x06\x07\x08",
       10},
      {INT64_MIN, "\x02\x08\x80\x00\x00\x00\x00\x00\x00\x00", 10},
      {INT64_MAX, "\x02\x08\x7f\xff\xff\xff\xff\xff\xff\xff", 10},
  };
  
  struct ASN1InvalidInt64Test {
    const char *encoding;
    size_t encoding_len;
  };
  
  static const ASN1InvalidInt64Test kASN1InvalidInt64Tests[] = {
      // Bad tag.
      {"\x03\x01\x00", 3},
      // Empty contents.
      {"\x02\x00", 2},
      // Overflow.
      {"\x02\x09\x01\x00\x00\x00\x00\x00\x00\x00\x00", 11},
      // Leading zeros.
      {"\x02\x02\x00\x01", 4},
      // Leading 0xff.
      {"\x02\x02\xff\xff", 4},
  };
  
  TEST(CBSTest, ASN1Int64) {
    for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(kASN1Int64Tests); i++) {
      SCOPED_TRACE(i);
      const ASN1Int64Test *test = &kASN1Int64Tests[i];
      CBS cbs;
      int64_t value;
      uint8_t *out;
      size_t len;
  
      CBS_init(&cbs, (const uint8_t *)test->encoding, test->encoding_len);
      ASSERT_TRUE(CBS_get_asn1_int64(&cbs, &value));
      EXPECT_EQ(0u, CBS_len(&cbs));
      EXPECT_EQ(test->value, value);
  
      bssl::ScopedCBB cbb;
      ASSERT_TRUE(CBB_init(cbb.get(), 0));
      ASSERT_TRUE(CBB_add_asn1_int64(cbb.get(), test->value));
      ASSERT_TRUE(CBB_finish(cbb.get(), &out, &len));
      bssl::UniquePtr<uint8_t> scoper(out);
      EXPECT_EQ(Bytes(test->encoding, test->encoding_len), Bytes(out, len));
    }
  
    for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(kASN1InvalidInt64Tests); i++) {
      const ASN1InvalidInt64Test *test = &kASN1InvalidInt64Tests[i];
      CBS cbs;
      int64_t value;
  
      CBS_init(&cbs, (const uint8_t *)test->encoding, test->encoding_len);
      EXPECT_FALSE(CBS_get_asn1_int64(&cbs, &value));
    }
  }
  
  TEST(CBBTest, Zero) {
    CBB cbb;
    CBB_zero(&cbb);
    // Calling |CBB_cleanup| on a zero-state |CBB| must not crash.
    CBB_cleanup(&cbb);
  }
  
  TEST(CBBTest, Reserve) {
    uint8_t buf[10];
    uint8_t *ptr;
    size_t len;
    bssl::ScopedCBB cbb;
    ASSERT_TRUE(CBB_init_fixed(cbb.get(), buf, sizeof(buf)));
    // Too large.
    EXPECT_FALSE(CBB_reserve(cbb.get(), &ptr, 11));
  
    cbb.Reset();
    ASSERT_TRUE(CBB_init_fixed(cbb.get(), buf, sizeof(buf)));
    // Successfully reserve the entire space.
    ASSERT_TRUE(CBB_reserve(cbb.get(), &ptr, 10));
    EXPECT_EQ(buf, ptr);
    // Advancing under the maximum bytes is legal.
    ASSERT_TRUE(CBB_did_write(cbb.get(), 5));
    ASSERT_TRUE(CBB_finish(cbb.get(), NULL, &len));
    EXPECT_EQ(5u, len);
  }
  
  // Test that CBB errors are sticky; once on operation on CBB fails, all
  // subsequent ones do.
  TEST(CBBTest, StickyError) {
    // Write an input that exceeds the limit for its length prefix.
    bssl::ScopedCBB cbb;
    CBB child;
    static const uint8_t kZeros[256] = {0};
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_TRUE(CBB_add_u8_length_prefixed(cbb.get(), &child));
    ASSERT_TRUE(CBB_add_bytes(&child, kZeros, sizeof(kZeros)));
    ASSERT_FALSE(CBB_flush(cbb.get()));
  
    // All future operations should fail.
    uint8_t *ptr;
    size_t len;
    EXPECT_FALSE(CBB_add_u8(cbb.get(), 0));
    EXPECT_FALSE(CBB_finish(cbb.get(), &ptr, &len));
  
    // Write an input that cannot fit in a fixed CBB.
    cbb.Reset();
    uint8_t buf;
    ASSERT_TRUE(CBB_init_fixed(cbb.get(), &buf, 1));
    ASSERT_FALSE(CBB_add_bytes(cbb.get(), kZeros, sizeof(kZeros)));
  
    // All future operations should fail.
    EXPECT_FALSE(CBB_add_u8(cbb.get(), 0));
    EXPECT_FALSE(CBB_finish(cbb.get(), &ptr, &len));
  
    // Write a u32 that cannot fit in a u24.
    cbb.Reset();
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    ASSERT_FALSE(CBB_add_u24(cbb.get(), 1u << 24));
  
    // All future operations should fail.
    EXPECT_FALSE(CBB_add_u8(cbb.get(), 0));
    EXPECT_FALSE(CBB_finish(cbb.get(), &ptr, &len));
  }
  
  TEST(CBSTest, BitString) {
    static const std::vector<uint8_t> kValidBitStrings[] = {
        {0x00},                                      // 0 bits
        {0x07, 0x80},                                // 1 bit
        {0x04, 0xf0},                                // 4 bits
        {0x00, 0xff},                                // 8 bits
        {0x06, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc0},  // 42 bits
    };
    for (const auto& test : kValidBitStrings) {
      SCOPED_TRACE(Bytes(test.data(), test.size()));
      CBS cbs;
      CBS_init(&cbs, test.data(), test.size());
      EXPECT_TRUE(CBS_is_valid_asn1_bitstring(&cbs));
    }
  
    static const std::vector<uint8_t> kInvalidBitStrings[] = {
        // BIT STRINGs always have a leading byte.
        std::vector<uint8_t>{},
        // It's not possible to take an unused bit off the empty string.
        {0x01},
        // There can be at most 7 unused bits.
        {0x08, 0xff},
        {0xff, 0xff},
        // All unused bits must be cleared.
        {0x06, 0xff, 0xc1},
    };
    for (const auto& test : kInvalidBitStrings) {
      SCOPED_TRACE(Bytes(test.data(), test.size()));
      CBS cbs;
      CBS_init(&cbs, test.data(), test.size());
      EXPECT_FALSE(CBS_is_valid_asn1_bitstring(&cbs));
  
      // CBS_asn1_bitstring_has_bit returns false on invalid inputs.
      EXPECT_FALSE(CBS_asn1_bitstring_has_bit(&cbs, 0));
    }
  
    static const struct {
      std::vector<uint8_t> in;
      unsigned bit;
      bool bit_set;
    } kBitTests[] = {
        // Basic tests.
        {{0x00}, 0, false},
        {{0x07, 0x80}, 0, true},
        {{0x06, 0x0f, 0x40}, 0, false},
        {{0x06, 0x0f, 0x40}, 1, false},
        {{0x06, 0x0f, 0x40}, 2, false},
        {{0x06, 0x0f, 0x40}, 3, false},
        {{0x06, 0x0f, 0x40}, 4, true},
        {{0x06, 0x0f, 0x40}, 5, true},
        {{0x06, 0x0f, 0x40}, 6, true},
        {{0x06, 0x0f, 0x40}, 7, true},
        {{0x06, 0x0f, 0x40}, 8, false},
        {{0x06, 0x0f, 0x40}, 9, true},
        // Out-of-bounds bits return 0.
        {{0x06, 0x0f, 0x40}, 10, false},
        {{0x06, 0x0f, 0x40}, 15, false},
        {{0x06, 0x0f, 0x40}, 16, false},
        {{0x06, 0x0f, 0x40}, 1000, false},
    };
    for (const auto& test : kBitTests) {
      SCOPED_TRACE(Bytes(test.in.data(), test.in.size()));
      SCOPED_TRACE(test.bit);
      CBS cbs;
      CBS_init(&cbs, test.in.data(), test.in.size());
      EXPECT_EQ(static_cast<int>(test.bit_set),
                CBS_asn1_bitstring_has_bit(&cbs, test.bit));
    }
  }
  
  TEST(CBBTest, AddOIDFromText) {
    const struct {
      const char *text;
      std::vector<uint8_t> der;
    } kValidOIDs[] = {
        // Some valid values.
        {"0.0", {0x00}},
        {"0.2.3.4", {0x2, 0x3, 0x4}},
        {"1.2.3.4", {0x2a, 0x3, 0x4}},
        {"2.2.3.4", {0x52, 0x3, 0x4}},
        {"1.2.840.113554.4.1.72585",
         {0x2a, 0x86, 0x48, 0x86, 0xf7, 0x12, 0x04, 0x01, 0x84, 0xb7, 0x09}},
        // Test edge cases around the first component.
        {"0.39", {0x27}},
        {"1.0", {0x28}},
        {"1.39", {0x4f}},
        {"2.0", {0x50}},
        {"2.1", {0x51}},
        {"2.40", {0x78}},
        // Edge cases near an overflow.
        {"1.2.18446744073709551615",
         {0x2a, 0x81, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f}},
        {"2.18446744073709551535",
         {0x81, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f}},
    };
  
    const char *kInvalidTexts[] = {
        // Invalid second component.
        "0.40",
        "1.40",
        // Invalid first component.
        "3.1",
        // The empty string is not an OID.
        "",
        // No empty components.
        ".1.2.3.4.5",
        "1..2.3.4.5",
        "1.2.3.4.5.",
        // There must be at least two components.
        "1",
        // No extra leading zeros.
        "00.1.2.3.4",
        "01.1.2.3.4",
        // Overflow for both components or 40*A + B.
        "1.2.18446744073709551616",
        "2.18446744073709551536",
    };
  
    const std::vector<uint8_t> kInvalidDER[] = {
        // The empty string is not an OID.
        {},
        // Non-minimal representation.
        {0x80, 0x01},
        // Overflow. This is the DER representation of
        // 1.2.840.113554.4.1.72585.18446744073709551616. (The final value is
        // 2^64.)
        {0x2a, 0x86, 0x48, 0x86, 0xf7, 0x12, 0x04, 0x01, 0x84, 0xb7, 0x09,
         0x82, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x00},
    };
  
    for (const auto &t : kValidOIDs) {
      SCOPED_TRACE(t.text);
  
      bssl::ScopedCBB cbb;
      ASSERT_TRUE(CBB_init(cbb.get(), 0));
      ASSERT_TRUE(CBB_add_asn1_oid_from_text(cbb.get(), t.text, strlen(t.text)));
      uint8_t *out;
      size_t len;
      ASSERT_TRUE(CBB_finish(cbb.get(), &out, &len));
      bssl::UniquePtr<uint8_t> free_out(out);
      EXPECT_EQ(Bytes(t.der), Bytes(out, len));
  
      CBS cbs;
      CBS_init(&cbs, t.der.data(), t.der.size());
      bssl::UniquePtr<char> text(CBS_asn1_oid_to_text(&cbs));
      ASSERT_TRUE(text.get());
      EXPECT_STREQ(t.text, text.get());
    }
  
    for (const char *t : kInvalidTexts) {
      SCOPED_TRACE(t);
      bssl::ScopedCBB cbb;
      ASSERT_TRUE(CBB_init(cbb.get(), 0));
      EXPECT_FALSE(CBB_add_asn1_oid_from_text(cbb.get(), t, strlen(t)));
    }
  
    for (const auto &t : kInvalidDER) {
      SCOPED_TRACE(Bytes(t));
      CBS cbs;
      CBS_init(&cbs, t.data(), t.size());
      bssl::UniquePtr<char> text(CBS_asn1_oid_to_text(&cbs));
      EXPECT_FALSE(text);
    }
  }
  
  TEST(CBBTest, FlushASN1SetOf) {
    const struct {
      std::vector<uint8_t> in, out;
    } kValidInputs[] = {
      // No elements.
      {{}, {}},
      // One element.
      {{0x30, 0x00}, {0x30, 0x00}},
      // Two identical elements.
      {{0x30, 0x00, 0x30, 0x00}, {0x30, 0x00, 0x30, 0x00}},
      // clang-format off
      {{0x30, 0x02, 0x00, 0x00,
        0x30, 0x00,
        0x01, 0x00,
        0x30, 0x02, 0x00, 0x00,
        0x30, 0x03, 0x00, 0x00, 0x00,
        0x30, 0x00,
        0x30, 0x03, 0x00, 0x00, 0x01,
        0x30, 0x01, 0x00,
        0x01, 0x01, 0x00},
       {0x01, 0x00,
        0x01, 0x01, 0x00,
        0x30, 0x00,
        0x30, 0x00,
        0x30, 0x01, 0x00,
        0x30, 0x02, 0x00, 0x00,
        0x30, 0x02, 0x00, 0x00,
        0x30, 0x03, 0x00, 0x00, 0x00,
        0x30, 0x03, 0x00, 0x00, 0x01}},
      // clang-format on
    };
  
    for (const auto &t : kValidInputs) {
      SCOPED_TRACE(Bytes(t.in));
  
      bssl::ScopedCBB cbb;
      CBB child;
      ASSERT_TRUE(CBB_init(cbb.get(), 0));
      ASSERT_TRUE(CBB_add_asn1(cbb.get(), &child, CBS_ASN1_SET));
      ASSERT_TRUE(CBB_add_bytes(&child, t.in.data(), t.in.size()));
      ASSERT_TRUE(CBB_flush_asn1_set_of(&child));
      EXPECT_EQ(Bytes(t.out), Bytes(CBB_data(&child), CBB_len(&child)));
  
      // Running it again should be idempotent.
      ASSERT_TRUE(CBB_flush_asn1_set_of(&child));
      EXPECT_EQ(Bytes(t.out), Bytes(CBB_data(&child), CBB_len(&child)));
  
      // The ASN.1 header remain intact.
      ASSERT_TRUE(CBB_flush(cbb.get()));
      EXPECT_EQ(0x31, CBB_data(cbb.get())[0]);
    }
  
    const std::vector<uint8_t> kInvalidInputs[] = {
      {0x30},
      {0x30, 0x01},
      {0x30, 0x00, 0x30, 0x00, 0x30, 0x01},
    };
  
    for (const auto &t : kInvalidInputs) {
      SCOPED_TRACE(Bytes(t));
  
      bssl::ScopedCBB cbb;
      CBB child;
      ASSERT_TRUE(CBB_init(cbb.get(), 0));
      ASSERT_TRUE(CBB_add_asn1(cbb.get(), &child, CBS_ASN1_SET));
      ASSERT_TRUE(CBB_add_bytes(&child, t.data(), t.size()));
      EXPECT_FALSE(CBB_flush_asn1_set_of(&child));
    }
  }
  
  template <class T>
  static std::vector<uint8_t> LiteralToBytes(const T *str) {
    std::vector<uint8_t> ret;
    for (; *str != 0; str++) {
      for (size_t i = 0; i < sizeof(T); i++) {
        ret.push_back(static_cast<uint8_t>(*str >> (8 * (sizeof(T) - 1 - i))));
      }
    }
    return ret;
  }
  
  static std::vector<uint32_t> LiteralToCodePoints(const char32_t *str) {
    std::vector<uint32_t> ret;
    for (; *str != 0; str++) {
      ret.push_back(static_cast<uint32_t>(*str));
    }
    return ret;
  }
  
  TEST(CBBTest, Unicode) {
    struct {
      int (*decode)(CBS *, uint32_t *);
      int (*encode)(CBB *, uint32_t);
      std::vector<uint8_t> in;
      std::vector<uint32_t> out;
      bool ok;
    } kTests[] = {
        {cbs_get_utf8, cbb_add_utf8,
         // This test string captures all four cases in UTF-8.
         LiteralToBytes(u8"Hello, 世界! ¡Hola, 🌎!"),
         LiteralToCodePoints(U"Hello, 世界! ¡Hola, 🌎!"), true},
  
        // Some invalid inputs adapted from
        // http://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-test.txt
        // 2.1  First possible sequence of a certain length. (5- and 6-bit
        // sequences no longer exist.)
        {cbs_get_utf8, cbb_add_utf8, {0xf8, 0x88, 0x80, 0x80, 0x80}, {}, false},
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xfc, 0x84, 0x80, 0x80, 0x80, 0x80},
         {},
         false},
        // 3.1  Unexpected continuation bytes.
        {cbs_get_utf8, cbb_add_utf8, {0x80}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xbf}, {}, false},
        // 3.2  Lonely start characters.
        {cbs_get_utf8, cbb_add_utf8, {0xc0, ' '}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xe0, ' '}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xf0, ' '}, {}, false},
        // 3.3  Sequences with last continuation byte missing
        {cbs_get_utf8, cbb_add_utf8, {0xc0}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xe0, 0x80}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xf0, 0x80, 0x80}, {}, false},
        // Variation of the above with unexpected spaces.
        {cbs_get_utf8, cbb_add_utf8, {0xe0, 0x80, ' '}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xf0, 0x80, 0x80, ' '}, {}, false},
        // 4.1  Examples of an overlong ASCII character
        {cbs_get_utf8, cbb_add_utf8, {0xc0, 0xaf}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xe0, 0x80, 0xaf}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xf0, 0x80, 0x80, 0xaf}, {}, false},
        // 4.2  Maximum overlong sequences
        {cbs_get_utf8, cbb_add_utf8, {0xc1, 0xbf}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xe0, 0x9f, 0xbf}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xf0, 0x8f, 0xbf, 0xbf}, {}, false},
        // 4.3  Overlong representation of the NUL character
        {cbs_get_utf8, cbb_add_utf8, {0xc0, 0x80}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xe0, 0x80, 0x80}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xf0, 0x80, 0x80, 0x80}, {}, false},
        // 5.1  Single UTF-16 surrogates
        {cbs_get_utf8, cbb_add_utf8, {0xed, 0xa0, 0x80}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xed, 0xad, 0xbf}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xed, 0xae, 0x80}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xed, 0xb0, 0x80}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xed, 0xbe, 0x80}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xed, 0xbf, 0xbf}, {}, false},
        // 5.2  Paired UTF-16 surrogates
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xed, 0xa0, 0x80, 0xed, 0xb0, 0x80},
         {},
         false},
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xed, 0xa0, 0x80, 0xed, 0xbf, 0xbf},
         {},
         false},
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xed, 0xad, 0xbf, 0xed, 0xb0, 0x80},
         {},
         false},
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xed, 0xad, 0xbf, 0xed, 0xbf, 0xbf},
         {},
         false},
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xed, 0xae, 0x80, 0xed, 0xb0, 0x80},
         {},
         false},
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xed, 0xae, 0x80, 0xed, 0xbf, 0xbf},
         {},
         false},
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xed, 0xaf, 0xbf, 0xed, 0xb0, 0x80},
         {},
         false},
        {cbs_get_utf8,
         cbb_add_utf8,
         {0xed, 0xaf, 0xbf, 0xed, 0xbf, 0xbf},
         {},
         false},
        // 5.3  Noncharacter code positions
        {cbs_get_utf8, cbb_add_utf8, {0xef, 0xbf, 0xbe}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xef, 0xbf, 0xbf}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xef, 0xb7, 0x90}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xef, 0xb7, 0xaf}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xf0, 0x9f, 0xbf, 0xbe}, {}, false},
        {cbs_get_utf8, cbb_add_utf8, {0xf0, 0x9f, 0xbf, 0xbf}, {}, false},
  
        {cbs_get_latin1, cbb_add_latin1, LiteralToBytes("\xa1Hola!"),
         LiteralToCodePoints(U"¡Hola!"), true},
  
        // UCS-2 matches UTF-16 on the BMP.
        {cbs_get_ucs2_be, cbb_add_ucs2_be, LiteralToBytes(u"Hello, 世界!"),
         LiteralToCodePoints(U"Hello, 世界!"), true},
        // It does not support characters beyond the BMP.
        {cbs_get_ucs2_be, cbb_add_ucs2_be,
         LiteralToBytes(u"Hello, 世界! ¡Hola, 🌎!"),
         LiteralToCodePoints(U"Hello, 世界! ¡Hola, "), false},
        // Unpaired surrogates and non-characters are also rejected.
        {cbs_get_ucs2_be, cbb_add_ucs2_be, {0xd8, 0x00}, {}, false},
        {cbs_get_ucs2_be, cbb_add_ucs2_be, {0xff, 0xfe}, {}, false},
  
        {cbs_get_utf32_be, cbb_add_utf32_be,
         LiteralToBytes(U"Hello, 世界! ¡Hola, 🌎!"),
         LiteralToCodePoints(U"Hello, 世界! ¡Hola, 🌎!"), true},
        // Unpaired surrogates and non-characters are rejected.
        {cbs_get_utf32_be, cbb_add_utf32_be, {0x00, 0x00, 0xd8, 0x00}, {}, false},
        {cbs_get_utf32_be, cbb_add_utf32_be, {0x00, 0x00, 0xff, 0xfe}, {}, false},
  
        // Test that the NUL character can be encoded.
        {cbs_get_latin1, cbb_add_latin1, {0}, {0}, true},
        {cbs_get_utf8, cbb_add_utf8, {0}, {0}, true},
        {cbs_get_ucs2_be, cbb_add_ucs2_be, {0, 0}, {0}, true},
        {cbs_get_utf32_be, cbb_add_utf32_be, {0, 0, 0, 0}, {0}, true},
    };
    for (const auto &t : kTests) {
      SCOPED_TRACE(Bytes(t.in));
  
      // Test decoding.
      CBS cbs;
      CBS_init(&cbs, t.in.data(), t.in.size());
      std::vector<uint32_t> out;
      bool ok = true;
      while (CBS_len(&cbs) != 0) {
        uint32_t u;
        if (!t.decode(&cbs, &u)) {
          ok = false;
          break;
        }
        out.push_back(u);
      }
      EXPECT_EQ(t.ok, ok);
      EXPECT_EQ(t.out, out);
  
      // Test encoding.
      if (t.ok) {
        bssl::ScopedCBB cbb;
        ASSERT_TRUE(CBB_init(cbb.get(), 0));
        for (uint32_t u : t.out) {
          ASSERT_TRUE(t.encode(cbb.get(), u));
        }
        EXPECT_EQ(Bytes(t.in), Bytes(CBB_data(cbb.get()), CBB_len(cbb.get())));
      }
    }
  
    static const uint32_t kBadCodePoints[] = {
      // Surrogate pairs.
      0xd800,
      0xdfff,
      // Non-characters.
      0xfffe,
      0xffff,
      0xfdd0,
      0x1fffe,
      0x1ffff,
      // Too big.
      0x110000,
    };
    bssl::ScopedCBB cbb;
    ASSERT_TRUE(CBB_init(cbb.get(), 0));
    for (uint32_t v : kBadCodePoints) {
      SCOPED_TRACE(v);
      EXPECT_FALSE(cbb_add_utf8(cbb.get(), v));
      EXPECT_FALSE(cbb_add_latin1(cbb.get(), v));
      EXPECT_FALSE(cbb_add_ucs2_be(cbb.get(), v));
      EXPECT_FALSE(cbb_add_utf32_be(cbb.get(), v));
    }
  
    // Additional values that are out of range.
    EXPECT_FALSE(cbb_add_latin1(cbb.get(), 0x100));
    EXPECT_FALSE(cbb_add_ucs2_be(cbb.get(), 0x10000));
  
    EXPECT_EQ(1u, cbb_get_utf8_len(0));
    EXPECT_EQ(1u, cbb_get_utf8_len(0x7f));
    EXPECT_EQ(2u, cbb_get_utf8_len(0x80));
    EXPECT_EQ(2u, cbb_get_utf8_len(0x7ff));
    EXPECT_EQ(3u, cbb_get_utf8_len(0x800));
    EXPECT_EQ(3u, cbb_get_utf8_len(0xffff));
    EXPECT_EQ(4u, cbb_get_utf8_len(0x10000));
    EXPECT_EQ(4u, cbb_get_utf8_len(0x10ffff));
  }
  