Roll inspector_protocol to 87e75896dcfcafda7869b0c9714db9b6cdc4c765

This lets us accept spec-compliant CBOR tag for message envelopes.

This also includes a change in v8-inspector-session-impl.cc that
relaxes an envelope check to allow spec-compliant envelopes.

Change-Id: Id77c1e0fc4b62d78e8580f81ef38d50e3eb54a1d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3662540Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80761}

src/inspector/v8-inspector-session-impl.cc

@@ -34,8 +34,10 @@ using v8_crdtp::json::ConvertCBORToJSON;
 using v8_crdtp::json::ConvertJSONToCBOR;
 
 bool IsCBORMessage(StringView msg) {
-  return msg.is8Bit() && msg.length() >= 2 && msg.characters8()[0] == 0xd8 &&
-         msg.characters8()[1] == 0x5a;
+  if (!msg.is8Bit() || msg.length() < 3) return false;
+  const uint8_t* bytes = msg.characters8();
+  return bytes[0] == 0xd8 &&
+         (bytes[1] == 0x5a || (bytes[1] == 0x18 && bytes[2] == 0x5a));
 }
 
 Status ConvertToCBOR(StringView state, std::vector<uint8_t>* cbor) {

third_party/inspector_protocol/README.v8

@@ -2,7 +2,7 @@ Name: inspector protocol
 Short Name: inspector_protocol
 URL: https://chromium.googlesource.com/deps/inspector_protocol/
 Version: 0
-Revision: 817313aa48ebb9a53cba1bd88bbe6a1c5048060c
+Revision: 87e75896dcfcafda7869b0c9714db9b6cdc4c765
 License: BSD
 License File: LICENSE
 Security Critical: no

third_party/inspector_protocol/crdtp/cbor.cc

@@ -46,7 +46,13 @@ constexpr uint8_t EncodeInitialByte(MajorType type, uint8_t additional_info) {
 // byte string carries its size (byte length).
 // https://tools.ietf.org/html/rfc7049#section-2.4.4.1
 static constexpr uint8_t kInitialByteForEnvelope =
-    EncodeInitialByte(MajorType::TAG, 24);
+    EncodeInitialByte(MajorType::TAG, kAdditionalInformation1Byte);
+
+// The standalone byte for "envelope" tag, to follow kInitialByteForEnvelope
+// in the correct implementation, as it is above in-tag value max (which is
+// also, confusingly, 24). See EnvelopeHeader::Parse() for more.
+static constexpr uint8_t kCBOREnvelopeTag = 24;
+
 // The initial byte for a byte string with at most 2^32 bytes
 // of payload. This is used for envelope encoding, even if
 // the byte string is shorter.
@@ -190,30 +196,25 @@ void WriteTokenStart(MajorType type,
 // Detecting CBOR content
 // =============================================================================
 
-uint8_t InitialByteForEnvelope() {
-  return kInitialByteForEnvelope;
-}
-
-uint8_t InitialByteFor32BitLengthByteString() {
-  return kInitialByteFor32BitLengthByteString;
-}
-
 bool IsCBORMessage(span<uint8_t> msg) {
-  return msg.size() >= 6 && msg[0] == InitialByteForEnvelope() &&
-         msg[1] == InitialByteFor32BitLengthByteString();
+  return msg.size() >= 4 && msg[0] == kInitialByteForEnvelope &&
+         (msg[1] == kInitialByteFor32BitLengthByteString ||
+          (msg[1] == kCBOREnvelopeTag &&
+           msg[2] == kInitialByteFor32BitLengthByteString));
 }
 
 Status CheckCBORMessage(span<uint8_t> msg) {
   if (msg.empty())
-    return Status(Error::CBOR_NO_INPUT, 0);
-  if (msg[0] != InitialByteForEnvelope())
+    return Status(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, 0);
+  if (msg[0] != kInitialByteForEnvelope)
     return Status(Error::CBOR_INVALID_START_BYTE, 0);
-  if (msg.size() < 6 || msg[1] != InitialByteFor32BitLengthByteString())
-    return Status(Error::CBOR_INVALID_ENVELOPE, 1);
-  if (msg[2] == 0 && msg[3] == 0 && msg[4] == 0 && msg[5] == 0)
-    return Status(Error::CBOR_INVALID_ENVELOPE, 1);
-  if (msg.size() < 7 || msg[6] != EncodeIndefiniteLengthMapStart())
-    return Status(Error::CBOR_MAP_START_EXPECTED, 6);
+  StatusOr<EnvelopeHeader> status_or_header = EnvelopeHeader::Parse(msg);
+  if (!status_or_header.ok())
+    return status_or_header.status();
+  const size_t pos = (*status_or_header).header_size();
+  assert(pos < msg.size());  // EnvelopeParser would not allow empty envelope.
+  if (msg[pos] != EncodeIndefiniteLengthMapStart())
+    return Status(Error::CBOR_MAP_START_EXPECTED, pos);
   return Status();
 }
 
@@ -324,11 +325,6 @@ void EncodeBinary(span<uint8_t> in, std::vector<uint8_t>* out) {
 // (kInitialByteForDouble) plus the 64 bits of payload for its value.
 constexpr size_t kEncodedDoubleSize = 1 + sizeof(uint64_t);
 
-// An envelope is encoded with a specific initial byte
-// (kInitialByteForEnvelope), plus the start byte for a BYTE_STRING with a 32
-// bit wide length, plus a 32 bit length for that string.
-constexpr size_t kEncodedEnvelopeHeaderSize = 1 + 1 + sizeof(uint32_t);
-
 void EncodeDouble(double value, std::vector<uint8_t>* out) {
   // The additional_info=27 indicates 64 bits for the double follow.
   // See RFC 7049 Section 2.3, Table 1.
@@ -348,6 +344,7 @@ void EncodeDouble(double value, std::vector<uint8_t>* out) {
 void EnvelopeEncoder::EncodeStart(std::vector<uint8_t>* out) {
   assert(byte_size_pos_ == 0);
   out->push_back(kInitialByteForEnvelope);
+  // TODO(caseq): encode tag as an additional byte here.
   out->push_back(kInitialByteFor32BitLengthByteString);
   byte_size_pos_ = out->size();
   out->resize(out->size() + sizeof(uint32_t));
@@ -369,6 +366,54 @@ bool EnvelopeEncoder::EncodeStop(std::vector<uint8_t>* out) {
   return true;
 }
 
+// static
+StatusOr<EnvelopeHeader> EnvelopeHeader::Parse(span<uint8_t> in) {
+  auto header_or_status = ParseFromFragment(in);
+  if (!header_or_status.ok())
+    return header_or_status;
+  if ((*header_or_status).outer_size() > in.size()) {
+    return StatusOr<EnvelopeHeader>(
+        Status(Error::CBOR_ENVELOPE_CONTENTS_LENGTH_MISMATCH, in.size()));
+  }
+  return header_or_status;
+}
+
+// static
+StatusOr<EnvelopeHeader> EnvelopeHeader::ParseFromFragment(span<uint8_t> in) {
+  // Our copy of StatusOr<> requires explicit constructor.
+  using Ret = StatusOr<EnvelopeHeader>;
+  constexpr size_t kMinEnvelopeSize = 2 + /* for envelope tag */
+                                      1 + /* for byte string */
+                                      1;  /* for contents, a map or an array */
+  if (in.size() < kMinEnvelopeSize)
+    return Ret(Status(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, in.size()));
+  assert(in[0] == kInitialByteForEnvelope);  // Caller should assure that.
+  size_t offset = 1;
+  // TODO(caseq): require this! We're currently accepting both a legacy,
+  // non spec-compliant envelope tag (that this implementation still currently
+  // produces), as well as a well-formed two-byte tag that a correct
+  // implementation should emit.
+  if (in[offset] == kCBOREnvelopeTag)
+    ++offset;
+  MajorType type;
+  uint64_t size;
+  size_t string_header_size =
+      internals::ReadTokenStart(in.subspan(offset), &type, &size);
+  if (!string_header_size)
+    return Ret(Status(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, in.size()));
+  if (type != MajorType::BYTE_STRING)
+    return Ret(Status(Error::CBOR_INVALID_ENVELOPE, offset));
+  // Do not allow empty envelopes -- at least an empty map/array should fit.
+  if (!size) {
+    return Ret(Status(Error::CBOR_MAP_OR_ARRAY_EXPECTED_IN_ENVELOPE,
+                      offset + string_header_size));
+  }
+  if (size > std::numeric_limits<uint32_t>::max())
+    return Ret(Status(Error::CBOR_INVALID_ENVELOPE, offset));
+  offset += string_header_size;
+  return Ret(EnvelopeHeader(offset, static_cast<size_t>(size)));
+}
+
 // =============================================================================
 // cbor::NewCBOREncoder - for encoding from a streaming parser
 // =============================================================================
@@ -490,8 +535,9 @@ std::unique_ptr<ParserHandler> NewCBOREncoder(std::vector<uint8_t>* out,
 // cbor::CBORTokenizer - for parsing individual CBOR items
 // =============================================================================
 
-CBORTokenizer::CBORTokenizer(span<uint8_t> bytes) : bytes_(bytes) {
-  ReadNextToken(/*enter_envelope=*/false);
+CBORTokenizer::CBORTokenizer(span<uint8_t> bytes)
+    : bytes_(bytes), status_(Error::OK, 0) {
+  ReadNextToken();
 }
 
 CBORTokenizer::~CBORTokenizer() {}
@@ -504,12 +550,12 @@ void CBORTokenizer::Next() {
   if (token_tag_ == CBORTokenTag::ERROR_VALUE ||
       token_tag_ == CBORTokenTag::DONE)
     return;
-  ReadNextToken(/*enter_envelope=*/false);
+  ReadNextToken();
 }
 
 void CBORTokenizer::EnterEnvelope() {
-  assert(token_tag_ == CBORTokenTag::ENVELOPE);
-  ReadNextToken(/*enter_envelope=*/true);
+  token_byte_length_ = GetEnvelopeHeader().header_size();
+  ReadNextToken();
 }
 
 Status CBORTokenizer::Status() const {
@@ -562,15 +608,18 @@ span<uint8_t> CBORTokenizer::GetBinary() const {
 }
 
 span<uint8_t> CBORTokenizer::GetEnvelope() const {
-  assert(token_tag_ == CBORTokenTag::ENVELOPE);
-  auto length = static_cast<size_t>(token_start_internal_value_);
-  return bytes_.subspan(status_.pos, length + kEncodedEnvelopeHeaderSize);
+  return bytes_.subspan(status_.pos, GetEnvelopeHeader().outer_size());
 }
 
 span<uint8_t> CBORTokenizer::GetEnvelopeContents() const {
+  const EnvelopeHeader& header = GetEnvelopeHeader();
+  return bytes_.subspan(status_.pos + header.header_size(),
+                        header.content_size());
+}
+
+const EnvelopeHeader& CBORTokenizer::GetEnvelopeHeader() const {
   assert(token_tag_ == CBORTokenTag::ENVELOPE);
-  auto length = static_cast<size_t>(token_start_internal_value_);
-  return bytes_.subspan(status_.pos + kEncodedEnvelopeHeaderSize, length);
+  return envelope_header_;
 }
 
 // All error checking happens in ::ReadNextToken, so that the accessors
@@ -600,14 +649,10 @@ static const uint64_t kMaxValidLength =
     std::min<uint64_t>(std::numeric_limits<uint64_t>::max() >> 2,
                        std::numeric_limits<size_t>::max());
 
-void CBORTokenizer::ReadNextToken(bool enter_envelope) {
-  if (enter_envelope) {
-    status_.pos += kEncodedEnvelopeHeaderSize;
-  } else {
-    status_.pos =
-        status_.pos == Status::npos() ? 0 : status_.pos + token_byte_length_;
-  }
+void CBORTokenizer::ReadNextToken() {
+  status_.pos += token_byte_length_;
   status_.error = Error::OK;
+  envelope_header_ = EnvelopeHeader();
   if (status_.pos >= bytes_.size()) {
     token_tag_ = CBORTokenTag::DONE;
     return;
@@ -660,29 +705,16 @@ void CBORTokenizer::ReadNextToken(bool enter_envelope) {
       return;
     }
     case kInitialByteForEnvelope: {  // ENVELOPE
-      if (kEncodedEnvelopeHeaderSize > remaining_bytes) {
-        SetError(Error::CBOR_INVALID_ENVELOPE);
-        return;
-      }
-      // The envelope must be a byte string with 32 bit length.
-      if (bytes_[status_.pos + 1] != kInitialByteFor32BitLengthByteString) {
-        SetError(Error::CBOR_INVALID_ENVELOPE);
+      StatusOr<EnvelopeHeader> status_or_header =
+          EnvelopeHeader::Parse(bytes_.subspan(status_.pos));
+      if (!status_or_header.ok()) {
+        status_.pos += status_or_header.status().pos;
+        SetError(status_or_header.status().error);
         return;
       }
-      // Read the length of the byte string.
-      token_start_internal_value_ = ReadBytesMostSignificantByteFirst<uint32_t>(
-          bytes_.subspan(status_.pos + 2));
-      if (token_start_internal_value_ > kMaxValidLength) {
-        SetError(Error::CBOR_INVALID_ENVELOPE);
-        return;
-      }
-      uint64_t token_byte_length =
-          token_start_internal_value_ + kEncodedEnvelopeHeaderSize;
-      if (token_byte_length > remaining_bytes) {
-        SetError(Error::CBOR_INVALID_ENVELOPE);
-        return;
-      }
-      SetToken(CBORTokenTag::ENVELOPE, static_cast<size_t>(token_byte_length));
+      assert((*status_or_header).outer_size() <= remaining_bytes);
+      envelope_header_ = *status_or_header;
+      SetToken(CBORTokenTag::ENVELOPE, envelope_header_.outer_size());
       return;
     }
     default: {
@@ -795,9 +827,6 @@ bool ParseArray(int32_t stack_depth,
 bool ParseValue(int32_t stack_depth,
                 CBORTokenizer* tokenizer,
                 ParserHandler* out);
-bool ParseEnvelope(int32_t stack_depth,
-                   CBORTokenizer* tokenizer,
-                   ParserHandler* out);
 
 void ParseUTF16String(CBORTokenizer* tokenizer, ParserHandler* out) {
   std::vector<uint16_t> value;
@@ -823,9 +852,8 @@ bool ParseEnvelope(int32_t stack_depth,
   // expect to see after we're done parsing the envelope contents.
   // This way we can compare and produce an error if the contents
   // didn't fit exactly into the envelope length.
-  size_t pos_past_envelope = tokenizer->Status().pos +
-                             kEncodedEnvelopeHeaderSize +
-                             tokenizer->GetEnvelopeContents().size();
+  size_t pos_past_envelope =
+      tokenizer->Status().pos + tokenizer->GetEnvelopeHeader().outer_size();
   tokenizer->EnterEnvelope();
   switch (tokenizer->TokenTag()) {
     case CBORTokenTag::ERROR_VALUE:
@@ -983,7 +1011,7 @@ bool ParseMap(int32_t stack_depth,
 
 void ParseCBOR(span<uint8_t> bytes, ParserHandler* out) {
   if (bytes.empty()) {
-    out->HandleError(Status{Error::CBOR_NO_INPUT, 0});
+    out->HandleError(Status{Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, 0});
     return;
   }
   CBORTokenizer tokenizer(bytes);
@@ -1009,33 +1037,37 @@ void ParseCBOR(span<uint8_t> bytes, ParserHandler* out) {
 Status AppendString8EntryToCBORMap(span<uint8_t> string8_key,
                                    span<uint8_t> string8_value,
                                    std::vector<uint8_t>* cbor) {
-  // Careful below: Don't compare (*cbor)[idx] with a uint8_t, since
-  // it could be a char (signed!). Instead, use bytes.
-  span<uint8_t> bytes(reinterpret_cast<const uint8_t*>(cbor->data()),
-                      cbor->size());
+  span<uint8_t> bytes(cbor->data(), cbor->size());
   CBORTokenizer tokenizer(bytes);
   if (tokenizer.TokenTag() == CBORTokenTag::ERROR_VALUE)
     return tokenizer.Status();
   if (tokenizer.TokenTag() != CBORTokenTag::ENVELOPE)
     return Status(Error::CBOR_INVALID_ENVELOPE, 0);
-  size_t envelope_size = tokenizer.GetEnvelopeContents().size();
+  EnvelopeHeader env_header = tokenizer.GetEnvelopeHeader();
   size_t old_size = cbor->size();
-  if (old_size != envelope_size + kEncodedEnvelopeHeaderSize)
+  if (old_size != env_header.outer_size())
     return Status(Error::CBOR_INVALID_ENVELOPE, 0);
-  if (envelope_size == 0 ||
-      (tokenizer.GetEnvelopeContents()[0] != EncodeIndefiniteLengthMapStart()))
-    return Status(Error::CBOR_MAP_START_EXPECTED, kEncodedEnvelopeHeaderSize);
+  assert(env_header.content_size() > 0);
+  if (tokenizer.GetEnvelopeContents()[0] != EncodeIndefiniteLengthMapStart())
+    return Status(Error::CBOR_MAP_START_EXPECTED, env_header.header_size());
   if (bytes[bytes.size() - 1] != EncodeStop())
     return Status(Error::CBOR_MAP_STOP_EXPECTED, cbor->size() - 1);
+  // We generally accept envelope headers with size specified in all possible
+  // widths, but when it comes to modifying, we only support the fixed 4 byte
+  // widths that we produce.
+  const size_t byte_string_pos = bytes[1] == kCBOREnvelopeTag ? 2 : 1;
+  if (bytes[byte_string_pos] != kInitialByteFor32BitLengthByteString)
+    return Status(Error::CBOR_INVALID_ENVELOPE, byte_string_pos);
   cbor->pop_back();
   EncodeString8(string8_key, cbor);
   EncodeString8(string8_value, cbor);
   cbor->push_back(EncodeStop());
-  size_t new_envelope_size = envelope_size + (cbor->size() - old_size);
+  size_t new_envelope_size =
+      env_header.content_size() + (cbor->size() - old_size);
   if (new_envelope_size > std::numeric_limits<uint32_t>::max())
     return Status(Error::CBOR_ENVELOPE_SIZE_LIMIT_EXCEEDED, 0);
-  size_t size_pos = cbor->size() - new_envelope_size - sizeof(uint32_t);
-  uint8_t* out = reinterpret_cast<uint8_t*>(&cbor->at(size_pos));
+  std::vector<uint8_t>::iterator out =
+      cbor->begin() + env_header.header_size() - sizeof(int32_t);
   *(out++) = (new_envelope_size >> 24) & 0xff;
   *(out++) = (new_envelope_size >> 16) & 0xff;
   *(out++) = (new_envelope_size >> 8) & 0xff;

third_party/inspector_protocol/crdtp/cbor.h

@@ -43,13 +43,6 @@ namespace cbor {
 // Detecting CBOR content
 // =============================================================================
 
-// The first byte for an envelope, which we use for wrapping dictionaries
-// and arrays; and the byte that indicates a byte string with 32 bit length.
-// These two bytes start an envelope, and thereby also any CBOR message
-// produced or consumed by this protocol. See also |EnvelopeEncoder| below.
-uint8_t InitialByteForEnvelope();
-uint8_t InitialByteFor32BitLengthByteString();
-
 // Checks whether |msg| is a cbor message.
 bool IsCBORMessage(span<uint8_t> msg);
 
@@ -129,6 +122,29 @@ class EnvelopeEncoder {
   size_t byte_size_pos_ = 0;
 };
 
+class EnvelopeHeader {
+ public:
+  EnvelopeHeader() = default;
+  ~EnvelopeHeader() = default;
+
+  // Parse envelope. Implies that `in` accomodates the entire size of envelope.
+  static StatusOr<EnvelopeHeader> Parse(span<uint8_t> in);
+  // Parse envelope, but allow `in` to only include the beginning of the
+  // envelope.
+  static StatusOr<EnvelopeHeader> ParseFromFragment(span<uint8_t> in);
+
+  size_t header_size() const { return header_size_; }
+  size_t content_size() const { return content_size_; }
+  size_t outer_size() const { return header_size_ + content_size_; }
+
+ private:
+  EnvelopeHeader(size_t header_size, size_t content_size)
+      : header_size_(header_size), content_size_(content_size) {}
+
+  size_t header_size_ = 0;
+  size_t content_size_ = 0;
+};
+
 // =============================================================================
 // cbor::NewCBOREncoder - for encoding from a streaming parser
 // =============================================================================
@@ -256,17 +272,22 @@ class CBORTokenizer {
   // enclosing envelope (the header, basically).
   span<uint8_t> GetEnvelopeContents() const;
 
+  // To be called only if ::TokenTag() == CBORTokenTag::ENVELOPE.
+  // Returns the envelope header.
+  const EnvelopeHeader& GetEnvelopeHeader() const;
+
  private:
-  void ReadNextToken(bool enter_envelope);
+  void ReadNextToken();
   void SetToken(CBORTokenTag token, size_t token_byte_length);
   void SetError(Error error);
 
-  span<uint8_t> bytes_;
+  const span<uint8_t> bytes_;
   CBORTokenTag token_tag_;
   struct Status status_;
-  size_t token_byte_length_;
+  size_t token_byte_length_ = 0;
   MajorType token_start_type_;
   uint64_t token_start_internal_value_;
+  EnvelopeHeader envelope_header_;
 };
 
 // =============================================================================

third_party/inspector_protocol/crdtp/cbor_test.cc

@@ -21,6 +21,7 @@
 #include "test_platform.h"
 
 using testing::ElementsAreArray;
+using testing::Eq;
 
 namespace v8_crdtp {
 namespace cbor {
@@ -72,7 +73,7 @@ TEST(CheckCBORMessage, ValidCBORButNotValidMessage) {
 TEST(CheckCBORMessage, EmptyMessage) {
   std::vector<uint8_t> empty;
   Status status = CheckCBORMessage(SpanFrom(empty));
-  EXPECT_THAT(status, StatusIs(Error::CBOR_NO_INPUT, 0));
+  EXPECT_THAT(status, StatusIs(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, 0));
 }
 
 TEST(CheckCBORMessage, InvalidStartByte) {
@@ -86,25 +87,25 @@ TEST(CheckCBORMessage, InvalidStartByte) {
 TEST(CheckCBORMessage, InvalidEnvelopes) {
   std::vector<uint8_t> bytes = {0xd8, 0x5a};
   EXPECT_THAT(CheckCBORMessage(SpanFrom(bytes)),
-              StatusIs(Error::CBOR_INVALID_ENVELOPE, 1));
+              StatusIs(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, 2));
   bytes = {0xd8, 0x5a, 0};
   EXPECT_THAT(CheckCBORMessage(SpanFrom(bytes)),
-              StatusIs(Error::CBOR_INVALID_ENVELOPE, 1));
+              StatusIs(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, 3));
   bytes = {0xd8, 0x5a, 0, 0};
   EXPECT_THAT(CheckCBORMessage(SpanFrom(bytes)),
-              StatusIs(Error::CBOR_INVALID_ENVELOPE, 1));
+              StatusIs(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, 4));
   bytes = {0xd8, 0x5a, 0, 0, 0};
   EXPECT_THAT(CheckCBORMessage(SpanFrom(bytes)),
-              StatusIs(Error::CBOR_INVALID_ENVELOPE, 1));
+              StatusIs(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, 5));
   bytes = {0xd8, 0x5a, 0, 0, 0, 0};
   EXPECT_THAT(CheckCBORMessage(SpanFrom(bytes)),
-              StatusIs(Error::CBOR_INVALID_ENVELOPE, 1));
+              StatusIs(Error::CBOR_MAP_OR_ARRAY_EXPECTED_IN_ENVELOPE, 6));
 }
 
 TEST(CheckCBORMessage, MapStartExpected) {
   std::vector<uint8_t> bytes = {0xd8, 0x5a, 0, 0, 0, 1};
   EXPECT_THAT(CheckCBORMessage(SpanFrom(bytes)),
-              StatusIs(Error::CBOR_MAP_START_EXPECTED, 6));
+              StatusIs(Error::CBOR_ENVELOPE_CONTENTS_LENGTH_MISMATCH, 6));
 }
 
 // =============================================================================
@@ -871,12 +872,8 @@ TEST(ParseCBORTest, ParseCBORHelloWorld) {
 
 TEST(ParseCBORTest, UTF8IsSupportedInKeys) {
   const uint8_t kPayloadLen = 11;
-  std::vector<uint8_t> bytes = {cbor::InitialByteForEnvelope(),
-                                cbor::InitialByteFor32BitLengthByteString(),
-                                0,
-                                0,
-                                0,
-                                kPayloadLen};
+  std::vector<uint8_t> bytes = {0xd8, 0x5a,  // envelope
+                                0,    0,    0, kPayloadLen};
   bytes.push_back(cbor::EncodeIndefiniteLengthMapStart());
   // Two UTF16 chars.
   EncodeString8(SpanFrom("🌎"), &bytes);
@@ -901,7 +898,7 @@ TEST(ParseCBORTest, NoInputError) {
   std::unique_ptr<ParserHandler> json_writer =
       json::NewJSONEncoder(&out, &status);
   ParseCBOR(span<uint8_t>(in.data(), in.size()), json_writer.get());
-  EXPECT_THAT(status, StatusIs(Error::CBOR_NO_INPUT, 0u));
+  EXPECT_THAT(status, StatusIs(Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE, 0u));
   EXPECT_EQ("", out);
 }
 
@@ -954,6 +951,39 @@ TEST(ParseCBORTest, UnexpectedEofInMapError) {
   EXPECT_EQ("", out);
 }
 
+TEST(ParseCBORTest, EnvelopeEncodingLegacy) {
+  constexpr uint8_t kPayloadLen = 8;
+  std::vector<uint8_t> bytes = {0xd8, 0x5a, 0, 0, 0, kPayloadLen};  // envelope
+  bytes.push_back(cbor::EncodeIndefiniteLengthMapStart());
+  EncodeString8(SpanFrom("foo"), &bytes);
+  EncodeInt32(42, &bytes);
+  bytes.emplace_back(EncodeStop());
+  std::string out;
+  Status status;
+  std::unique_ptr<ParserHandler> json_writer =
+      json::NewJSONEncoder(&out, &status);
+  ParseCBOR(span<uint8_t>(bytes.data(), bytes.size()), json_writer.get());
+  EXPECT_THAT(status, StatusIsOk());
+  EXPECT_EQ(out, "{\"foo\":42}");
+}
+
+TEST(ParseCBORTest, EnvelopeEncodingBySpec) {
+  constexpr uint8_t kPayloadLen = 8;
+  std::vector<uint8_t> bytes = {0xd8, 0x18, 0x5a,       0,
+                                0,    0,    kPayloadLen};  // envelope
+  bytes.push_back(cbor::EncodeIndefiniteLengthMapStart());
+  EncodeString8(SpanFrom("foo"), &bytes);
+  EncodeInt32(42, &bytes);
+  bytes.emplace_back(EncodeStop());
+  std::string out;
+  Status status;
+  std::unique_ptr<ParserHandler> json_writer =
+      json::NewJSONEncoder(&out, &status);
+  ParseCBOR(span<uint8_t>(bytes.data(), bytes.size()), json_writer.get());
+  EXPECT_THAT(status, StatusIsOk());
+  EXPECT_EQ(out, "{\"foo\":42}");
+}
+
 TEST(ParseCBORTest, NoEmptyEnvelopesAllowed) {
   std::vector<uint8_t> bytes = {0xd8, 0x5a, 0, 0, 0, 0};  // envelope
   std::string out;
@@ -971,7 +1001,7 @@ TEST(ParseCBORTest, OnlyMapsAndArraysSupportedInsideEnvelopes) {
   // is an envelope that contains just a number (1). We don't
   // allow numbers to be contained in an envelope though, only
   // maps and arrays.
-  constexpr uint8_t kPayloadLen = 1;
+  constexpr uint8_t kPayloadLen = 8;
   std::vector<uint8_t> bytes = {0xd8,
                                 0x5a,
                                 0,
@@ -1247,6 +1277,69 @@ TEST(ParseCBORTest, EnvelopeContentsLengthMismatch) {
   EXPECT_EQ("", out);
 }
 
+// =============================================================================
+// cbor::EnvelopeHeader - for parsing envelope headers
+// =============================================================================
+// Note most of converage for this is historically on a higher level of
+// ParseCBOR(). This provides just a few essnetial scenarios for now.
+
+template <typename T>
+class EnvelopeHeaderTest : public ::testing::Test {};
+
+TEST(EnvelopeHeaderTest, EnvelopeStartLegacy) {
+  std::vector<uint8_t> bytes = {0xd8,             // Tag start
+                                0x5a,             // Byte string, 4 bytes length
+                                0,    0,   0, 2,  // Length
+                                0xbf, 0xff};      // map start / map end
+  auto result = EnvelopeHeader::Parse(SpanFrom(bytes));
+  ASSERT_THAT(result.status(), StatusIsOk());
+  EXPECT_THAT((*result).header_size(), Eq(6u));
+  EXPECT_THAT((*result).content_size(), Eq(2u));
+  EXPECT_THAT((*result).outer_size(), Eq(8u));
+}
+
+TEST(EnvelopeHeaderTest, EnvelopeStartSpecCompliant) {
+  std::vector<uint8_t> bytes = {0xd8,             // Tag start
+                                0x18,             // Tag type (CBOR)
+                                0x5a,             // Byte string, 4 bytes length
+                                0,    0,   0, 2,  // Length
+                                0xbf, 0xff};      // map start / map end
+  auto result = EnvelopeHeader::Parse(SpanFrom(bytes));
+  ASSERT_THAT(result.status(), StatusIsOk());
+  EXPECT_THAT((*result).header_size(), Eq(7u));
+  EXPECT_THAT((*result).content_size(), Eq(2u));
+  EXPECT_THAT((*result).outer_size(), Eq(9u));
+}
+
+TEST(EnvelopeHeaderTest, EnvelopeStartShortLen) {
+  std::vector<uint8_t> bytes = {0xd8,         // Tag start
+                                0x18,         // Tag type (CBOR)
+                                0x58,         // Byte string, 1 byte length
+                                2,            // Length
+                                0xbf, 0xff};  // map start / map end
+  auto result = EnvelopeHeader::Parse(SpanFrom(bytes));
+  ASSERT_THAT(result.status(), StatusIsOk());
+  EXPECT_THAT((*result).header_size(), Eq(4u));
+  EXPECT_THAT((*result).content_size(), Eq(2u));
+  EXPECT_THAT((*result).outer_size(), Eq(6u));
+}
+
+TEST(EnvelopeHeaderTest, ParseFragment) {
+  std::vector<uint8_t> bytes = {0xd8,  // Tag start
+                                0x18,  // Tag type (CBOR)
+                                0x5a,  // Byte string, 4 bytes length
+                                0,    0, 0, 20, 0xbf};  // map start
+  auto result = EnvelopeHeader::ParseFromFragment(SpanFrom(bytes));
+  ASSERT_THAT(result.status(), StatusIsOk());
+  EXPECT_THAT((*result).header_size(), Eq(7u));
+  EXPECT_THAT((*result).content_size(), Eq(20u));
+  EXPECT_THAT((*result).outer_size(), Eq(27u));
+
+  result = EnvelopeHeader::Parse(SpanFrom(bytes));
+  ASSERT_THAT(result.status(),
+              StatusIs(Error::CBOR_ENVELOPE_CONTENTS_LENGTH_MISMATCH, 8));
+}
+
 // =============================================================================
 // cbor::AppendString8EntryToMap - for limited in-place editing of messages
 // =============================================================================
@@ -1331,7 +1424,7 @@ TEST(AppendString8EntryToMapTest, InvalidEnvelope_Error) {
         0xd8, 0x7a, 0, 0, 0, 2, EncodeIndefiniteLengthMapStart(), EncodeStop()};
     Status status =
         AppendString8EntryToCBORMap(SpanFrom("key"), SpanFrom("value"), &msg);
-    EXPECT_THAT(status, StatusIs(Error::CBOR_INVALID_ENVELOPE, 0u));
+    EXPECT_THAT(status, StatusIs(Error::CBOR_INVALID_ENVELOPE, 1u));
   }
   {  // Invalid envelope size example.
     std::vector<uint8_t> msg = {
@@ -1339,7 +1432,8 @@ TEST(AppendString8EntryToMapTest, InvalidEnvelope_Error) {
     };
     Status status =
         AppendString8EntryToCBORMap(SpanFrom("key"), SpanFrom("value"), &msg);
-    EXPECT_THAT(status, StatusIs(Error::CBOR_INVALID_ENVELOPE, 0u));
+    EXPECT_THAT(status,
+                StatusIs(Error::CBOR_ENVELOPE_CONTENTS_LENGTH_MISMATCH, 8u));
   }
   {  // Invalid envelope size example.
     std::vector<uint8_t> msg = {
@@ -1347,7 +1441,7 @@ TEST(AppendString8EntryToMapTest, InvalidEnvelope_Error) {
     };
     Status status =
         AppendString8EntryToCBORMap(SpanFrom("key"), SpanFrom("value"), &msg);
-    EXPECT_THAT(status, StatusIs(Error::CBOR_INVALID_ENVELOPE, 0u));
+    EXPECT_THAT(status, StatusIs(Error::CBOR_INVALID_ENVELOPE, 0));
   }
 }
 }  // namespace cbor

third_party/inspector_protocol/crdtp/dispatch.cc

@@ -78,13 +78,17 @@ DispatchResponse DispatchResponse::ServerError(std::string message) {
   return result;
 }
 
+// static
+DispatchResponse DispatchResponse::SessionNotFound(std::string message) {
+  DispatchResponse result;
+  result.code_ = DispatchCode::SESSION_NOT_FOUND;
+  result.message_ = std::move(message);
+  return result;
+}
+
 // =============================================================================
 // Dispatchable - a shallow parser for CBOR encoded DevTools messages
 // =============================================================================
-namespace {
-constexpr size_t kEncodedEnvelopeHeaderSize = 1 + 1 + sizeof(uint32_t);
-}  // namespace
-
 Dispatchable::Dispatchable(span<uint8_t> serialized) : serialized_(serialized) {
   Status s = cbor::CheckCBORMessage(serialized);
   if (!s.ok()) {
@@ -105,9 +109,8 @@ Dispatchable::Dispatchable(span<uint8_t> serialized) : serialized_(serialized) {
   // expect to see after we're done parsing the envelope contents.
   // This way we can compare and produce an error if the contents
   // didn't fit exactly into the envelope length.
-  const size_t pos_past_envelope = tokenizer.Status().pos +
-                                   kEncodedEnvelopeHeaderSize +
-                                   tokenizer.GetEnvelopeContents().size();
+  const size_t pos_past_envelope =
+      tokenizer.Status().pos + tokenizer.GetEnvelopeHeader().outer_size();
   tokenizer.EnterEnvelope();
   if (tokenizer.TokenTag() == cbor::CBORTokenTag::ERROR_VALUE) {
     status_ = tokenizer.Status();

third_party/inspector_protocol/crdtp/dispatch.h

@@ -38,6 +38,7 @@ enum class DispatchCode {
   INVALID_PARAMS = -32602,
   INTERNAL_ERROR = -32603,
   SERVER_ERROR = -32000,
+  SESSION_NOT_FOUND = SERVER_ERROR - 1,
 };
 
 // Information returned by command handlers. Usually returned after command
@@ -76,6 +77,10 @@ class DispatchResponse {
   // Used for application level errors, e.g. within protocol agents.
   static DispatchResponse ServerError(std::string message);
 
+  // Indicate that session with the id specified in the protocol message
+  // was not found (e.g. because it has already been detached).
+  static DispatchResponse SessionNotFound(std::string message);
+
  private:
   DispatchResponse() = default;
   DispatchCode code_;

third_party/inspector_protocol/crdtp/dispatch_test.cc

@@ -27,6 +27,13 @@ TEST(DispatchResponseTest, ServerError) {
   EXPECT_EQ("Oops!", error.Message());
 }
 
+TEST(DispatchResponseTest, SessionNotFound) {
+  DispatchResponse error = DispatchResponse::SessionNotFound("OMG!");
+  EXPECT_FALSE(error.IsSuccess());
+  EXPECT_EQ(DispatchCode::SESSION_NOT_FOUND, error.Code());
+  EXPECT_EQ("OMG!", error.Message());
+}
+
 TEST(DispatchResponseTest, InternalError) {
   DispatchResponse error = DispatchResponse::InternalError();
   EXPECT_FALSE(error.IsSuccess());

third_party/inspector_protocol/crdtp/status.cc

@@ -58,16 +58,16 @@ std::string Status::Message() const {
       return "CBOR: invalid binary";
     case Error::CBOR_UNSUPPORTED_VALUE:
       return "CBOR: unsupported value";
-    case Error::CBOR_NO_INPUT:
-      return "CBOR: no input";
+    case Error::CBOR_UNEXPECTED_EOF_IN_ENVELOPE:
+      return "CBOR: unexpected EOF reading envelope";
     case Error::CBOR_INVALID_START_BYTE:
       return "CBOR: invalid start byte";
     case Error::CBOR_UNEXPECTED_EOF_EXPECTED_VALUE:
-      return "CBOR: unexpected eof expected value";
+      return "CBOR: unexpected EOF expected value";
     case Error::CBOR_UNEXPECTED_EOF_IN_ARRAY:
-      return "CBOR: unexpected eof in array";
+      return "CBOR: unexpected EOF in array";
     case Error::CBOR_UNEXPECTED_EOF_IN_MAP:
-      return "CBOR: unexpected eof in map";
+      return "CBOR: unexpected EOF in map";
     case Error::CBOR_INVALID_MAP_KEY:
       return "CBOR: invalid map key";
     case Error::CBOR_DUPLICATE_MAP_KEY:

third_party/inspector_protocol/crdtp/status.h

@@ -46,7 +46,7 @@ enum class Error {
   CBOR_INVALID_STRING16 = 0x14,
   CBOR_INVALID_BINARY = 0x15,
   CBOR_UNSUPPORTED_VALUE = 0x16,
-  CBOR_NO_INPUT = 0x17,
+  CBOR_UNEXPECTED_EOF_IN_ENVELOPE = 0x17,
   CBOR_INVALID_START_BYTE = 0x18,
   CBOR_UNEXPECTED_EOF_EXPECTED_VALUE = 0x19,
   CBOR_UNEXPECTED_EOF_IN_ARRAY = 0x1a,
@@ -90,7 +90,7 @@ struct Status {
 
   Error error = Error::OK;
   size_t pos = npos();
-  Status(Error error, size_t pos) : error(error), pos(pos) {}
+  [[nodiscard]] Status(Error error, size_t pos) : error(error), pos(pos) {}
   Status() = default;
 
   bool IsMessageError() const {

third_party/inspector_protocol/lib/Values_cpp.template

@@ -31,7 +31,6 @@ using {{config.crdtp.namespace}}::cbor::EncodeStop;
 using {{config.crdtp.namespace}}::cbor::EncodeString8;
 using {{config.crdtp.namespace}}::cbor::EncodeTrue;
 using {{config.crdtp.namespace}}::cbor::EnvelopeEncoder;
-using {{config.crdtp.namespace}}::cbor::InitialByteForEnvelope;
 }  // namespace cbor
 
 // Uses the parsing events received from driver of |ParserHandler|