/// <summary>
/// Reads a varint from the input one byte at a time, so that it does not
/// read any bytes after the end of the varint. If you simply wrapped the
/// stream in a CodedInputStream and used ReadRawVarint32(Stream)
/// then you would probably end up reading past the end of the varint since
/// CodedInputStream buffers its input.
/// </summary>
/// <param name="input"></param>
/// <returns></returns>
public static uint ReadRawVarint32(Stream input)
{
int result = 0;
int offset = 0;
for (; offset < 32; offset += 7)
{
int b = input.ReadByte();
if (b == -1)
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
result |= (b & 0x7f) << offset;
if ((b & 0x80) == 0)
{
return((uint)result);
}
}
// Keep reading up to 64 bits.
for (; offset < 64; offset += 7)
{
int b = input.ReadByte();
if (b == -1)
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
if ((b & 0x80) == 0)
{
return((uint)result);
}
}
throw InvalidProtocolBufferException.MalformedVarint();
}
/// <summary>
/// Validates that the specified size doesn't exceed the current limit. If it does then remaining bytes
/// are skipped and an error is thrown.
/// </summary>
private static void ValidateCurrentLimit(ref ReadOnlySpan <byte> buffer, ref ParserInternalState state, int size)
{
if (state.totalBytesRetired + state.bufferPos + size > state.currentLimit)
{
// Read to the end of the stream (up to the current limit) anyway.
SkipRawBytes(ref buffer, ref state, state.currentLimit - state.totalBytesRetired - state.bufferPos);
// Then fail.
throw InvalidProtocolBufferException.TruncatedMessage();
}
}
private bool RefillFromReadOnlySequence(ref ReadOnlySpan <byte> buffer, ref ParserInternalState state, bool mustSucceed)
{
CheckCurrentBufferIsEmpty(ref state);
if (state.totalBytesRetired + state.bufferSize == state.currentLimit)
{
// Oops, we hit a limit.
if (mustSucceed)
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
else
{
return(false);
}
}
state.totalBytesRetired += state.bufferSize;
state.bufferPos = 0;
state.bufferSize = 0;
while (readOnlySequenceEnumerator.MoveNext())
{
buffer = readOnlySequenceEnumerator.Current.Span;
state.bufferSize = buffer.Length;
if (buffer.Length != 0)
{
break;
}
}
if (state.bufferSize == 0)
{
if (mustSucceed)
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
else
{
return(false);
}
}
else
{
RecomputeBufferSizeAfterLimit(ref state);
int totalBytesRead =
state.totalBytesRetired + state.bufferSize + state.bufferSizeAfterLimit;
if (totalBytesRead < 0 || totalBytesRead > state.sizeLimit)
{
throw InvalidProtocolBufferException.SizeLimitExceeded();
}
return(true);
}
}
private bool RefillFromCodedInputStream(ref ReadOnlySpan <byte> buffer, ref ParserInternalState state, bool mustSucceed)
{
CheckCurrentBufferIsEmpty(ref state);
if (state.totalBytesRetired + state.bufferSize == state.currentLimit)
{
// Oops, we hit a limit.
if (mustSucceed)
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
else
{
return(false);
}
}
Stream input = codedInputStream.InternalInputStream;
state.totalBytesRetired += state.bufferSize;
state.bufferPos = 0;
state.bufferSize = (input == null) ? 0 : input.Read(codedInputStream.InternalBuffer, 0, buffer.Length);
if (state.bufferSize < 0)
{
throw new InvalidOperationException("Stream.Read returned a negative count");
}
if (state.bufferSize == 0)
{
if (mustSucceed)
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
else
{
return(false);
}
}
else
{
RecomputeBufferSizeAfterLimit(ref state);
int totalBytesRead =
state.totalBytesRetired + state.bufferSize + state.bufferSizeAfterLimit;
if (totalBytesRead < 0 || totalBytesRead > state.sizeLimit)
{
throw InvalidProtocolBufferException.SizeLimitExceeded();
}
return(true);
}
}
/// <summary>
/// Sets currentLimit to (current position) + byteLimit. This is called
/// when descending into a length-delimited embedded message. The previous
/// limit is returned.
/// </summary>
/// <returns>The old limit.</returns>
public static int PushLimit(ref ParserInternalState state, int byteLimit)
{
if (byteLimit < 0)
{
throw InvalidProtocolBufferException.NegativeSize();
}
byteLimit += state.totalBytesRetired + state.bufferPos;
int oldLimit = state.currentLimit;
if (byteLimit > oldLimit)
{
throw InvalidProtocolBufferException.TruncatedMessage();
}
state.currentLimit = byteLimit;
RecomputeBufferSizeAfterLimit(ref state);
return(oldLimit);
}
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);
}
/// <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--;
}