#region Copyright notice and license
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#endregion
using System;
using System.Buffers;
using System.Collections.Generic;
using System.IO;
using System.Runtime.CompilerServices;
using System.Security;
using Google.Protobuf.Collections;
namespace Google.Protobuf
{
/// <summary>
/// Reading and skipping messages / groups
/// </summary>
[SecuritySafeCritical]
internal static class ParsingPrimitivesMessages
{
private static readonly byte[] ZeroLengthMessageStreamData = new byte[] { 0 };
public static void SkipLastField(ref ReadOnlySpan<byte> buffer, ref ParserInternalState state)
{
if (state.lastTag == 0)
{
throw new InvalidOperationException("SkipLastField cannot be called at the end of a stream");
}
switch (WireFormat.GetTagWireType(state.lastTag))
{
case WireFormat.WireType.StartGroup:
SkipGroup(ref buffer, ref state, state.lastTag);
break;
case WireFormat.WireType.EndGroup:
throw new InvalidProtocolBufferException(
"SkipLastField called on an end-group tag, indicating that the corresponding start-group was missing");
case WireFormat.WireType.Fixed32:
ParsingPrimitives.ParseRawLittleEndian32(ref buffer, ref state);
break;
case WireFormat.WireType.Fixed64:
ParsingPrimitives.ParseRawLittleEndian64(ref buffer, ref state);
break;
case WireFormat.WireType.LengthDelimited:
var length = ParsingPrimitives.ParseLength(ref buffer, ref state);
ParsingPrimitives.SkipRawBytes(ref buffer, ref state, length);
break;
case WireFormat.WireType.Varint:
ParsingPrimitives.ParseRawVarint32(ref buffer, ref state);
break;
}
}
/// <summary>
/// Skip a group.
/// </summary>
public static void SkipGroup(ref ReadOnlySpan<byte> buffer, ref ParserInternalState state, uint startGroupTag)
{
// Note: Currently we expect this to be the way that groups are read. We could put the recursion
// depth changes into the ReadTag method instead, potentially...
state.recursionDepth++;
if (state.recursionDepth >= state.recursionLimit)
{
throw InvalidProtocolBufferException.RecursionLimitExceeded();
}
uint tag;
while (true)
{
tag = ParsingPrimitives.ParseTag(ref buffer, ref state);
if (tag == 0)
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
// Can't call SkipLastField for this case- that would throw.
if (WireFormat.GetTagWireType(tag) == WireFormat.WireType.EndGroup)
{
break;
}
// This recursion will allow us to handle nested groups.
SkipLastField(ref buffer, ref state);
}
int startField = WireFormat.GetTagFieldNumber(startGroupTag);
int endField = WireFormat.GetTagFieldNumber(tag);
if (startField != endField)
{
throw new InvalidProtocolBufferException(
$"Mismatched end-group tag. Started with field {startField}; ended with field {endField}");
}
state.recursionDepth--;
}
public static void ReadMessage(ref ParseContext ctx, IMessage message)
{
int length = ParsingPrimitives.ParseLength(ref ctx.buffer, ref ctx.state);
if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
{
throw InvalidProtocolBufferException.RecursionLimitExceeded();
}
int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
++ctx.state.recursionDepth;
ReadRawMessage(ref ctx, message);
CheckReadEndOfStreamTag(ref ctx.state);
// Check that we've read exactly as much data as expected.
if (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
--ctx.state.recursionDepth;
SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);
}
public static KeyValuePair<TKey, TValue> ReadMapEntry<TKey, TValue>(ref ParseContext ctx, MapField<TKey, TValue>.Codec codec)
{
int length = ParsingPrimitives.ParseLength(ref ctx.buffer, ref ctx.state);
if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
{
throw InvalidProtocolBufferException.RecursionLimitExceeded();
}
int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
++ctx.state.recursionDepth;
TKey key = codec.KeyCodec.DefaultValue;
TValue value = codec.ValueCodec.DefaultValue;
uint tag;
while ((tag = ctx.ReadTag()) != 0)
{
if (tag == codec.KeyCodec.Tag)
{
key = codec.KeyCodec.Read(ref ctx);
}
else if (tag == codec.ValueCodec.Tag)
{
value = codec.ValueCodec.Read(ref ctx);
}
else
{
SkipLastField(ref ctx.buffer, ref ctx.state);
}
}
// Corner case: a map entry with a key but no value, where the value type is a message.
// Read it as if we'd seen input with no data (i.e. create a "default" message).
if (value == null)
{
if (ctx.state.CodedInputStream != null)
{
// the decoded message might not support parsing from ParseContext, so
// we need to allow fallback to the legacy MergeFrom(CodedInputStream) parsing.
value = codec.ValueCodec.Read(new CodedInputStream(ZeroLengthMessageStreamData));
}
else
{
ParseContext.Initialize(new ReadOnlySequence<byte>(ZeroLengthMessageStreamData), out ParseContext zeroLengthCtx);
value = codec.ValueCodec.Read(ref zeroLengthCtx);
}
}
CheckReadEndOfStreamTag(ref ctx.state);
// Check that we've read exactly as much data as expected.
if (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
--ctx.state.recursionDepth;
SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);
return new KeyValuePair<TKey, TValue>(key, value);
}
public static void ReadGroup(ref ParseContext ctx, IMessage message)
{
if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
{
throw InvalidProtocolBufferException.RecursionLimitExceeded();
}
++ctx.state.recursionDepth;
uint tag = ctx.state.lastTag;
int fieldNumber = WireFormat.GetTagFieldNumber(tag);
ReadRawMessage(ref ctx, message);
CheckLastTagWas(ref ctx.state, WireFormat.MakeTag(fieldNumber, WireFormat.WireType.EndGroup));
--ctx.state.recursionDepth;
}
public static void ReadGroup(ref ParseContext ctx, int fieldNumber, UnknownFieldSet set)
{
if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
{
throw InvalidProtocolBufferException.RecursionLimitExceeded();
}
++ctx.state.recursionDepth;
set.MergeGroupFrom(ref ctx);
CheckLastTagWas(ref ctx.state, WireFormat.MakeTag(fieldNumber, WireFormat.WireType.EndGroup));
--ctx.state.recursionDepth;
}
public static void ReadRawMessage(ref ParseContext ctx, IMessage message)
{
if (message is IBufferMessage bufferMessage)
{
bufferMessage.InternalMergeFrom(ref ctx);
}
else
{
// If we reached here, it means we've ran into a nested message with older generated code
// which doesn't provide the InternalMergeFrom method that takes a ParseContext.
// With a slight performance overhead, we can still parse this message just fine,
// but we need to find the original CodedInputStream instance that initiated this
// parsing process and make sure its internal state is up to date.
// Note that this performance overhead is not very high (basically copying contents of a struct)
// and it will only be incurred in case the application mixes older and newer generated code.
// Regenerating the code from .proto files will remove this overhead because it will
// generate the InternalMergeFrom method we need.
if (ctx.state.CodedInputStream == null)
{
// This can only happen when the parsing started without providing a CodedInputStream instance
// (e.g. ParseContext was created directly from a ReadOnlySequence).
// That also means that one of the new parsing APIs was used at the top level
// and in such case it is reasonable to require that all the nested message provide
// up-to-date generated code with ParseContext support (and fail otherwise).
throw new InvalidProtocolBufferException($"Message {message.GetType().Name} doesn't provide the generated method that enables ParseContext-based parsing. You might need to regenerate the generated protobuf code.");
}
ctx.CopyStateTo(ctx.state.CodedInputStream);
try
{
// fallback parse using the CodedInputStream that started current parsing tree
message.MergeFrom(ctx.state.CodedInputStream);
}
finally
{
ctx.LoadStateFrom(ctx.state.CodedInputStream);
}
}
}
/// <summary>
/// Verifies that the last call to ReadTag() returned tag 0 - in other words,
/// we've reached the end of the stream when we expected to.
/// </summary>
/// <exception cref="InvalidProtocolBufferException">The
/// tag read was not the one specified</exception>
public static void CheckReadEndOfStreamTag(ref ParserInternalState state)
{
if (state.lastTag != 0)
{
throw InvalidProtocolBufferException.MoreDataAvailable();
}
}
private static void CheckLastTagWas(ref ParserInternalState state, uint expectedTag)
{
if (state.lastTag != expectedTag) {
throw InvalidProtocolBufferException.InvalidEndTag();
}
}
}
}
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