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Support bypassing range check in ReadCompactSize

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This is needed when we want to encode an arbitrary number as CompactSize
like node service flags, which is a bitmask and could be bigger than the
usual size of an object.
This commit is contained in:
Pieter Wuille 2020-10-08 20:27:27 -07:00 committed by Vasil Dimov
parent 6af9b31bfc
commit 1d3ec2a1fd
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GPG key ID: 54DF06F64B55CBBF
1 changed files with 17 additions and 5 deletions
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22
src/serialize.h
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@ -24,7 +24,11 @@
#include <prevector.h>
#include <span.h>
static const unsigned int MAX_SIZE = 0x02000000;
/**
* The maximum size of a serialized object in bytes or number of elements
* (for eg vectors) when the size is encoded as CompactSize.
*/
static constexpr uint64_t MAX_SIZE = 0x02000000;
/** Maximum amount of memory (in bytes) to allocate at once when deserializing vectors. */
static const unsigned int MAX_VECTOR_ALLOCATE = 5000000;
@ -304,8 +308,14 @@ void WriteCompactSize(Stream& os, uint64_t nSize)
return;
}
/**
* Decode a CompactSize-encoded variable-length integer.
*
* As these are primarily used to encode the size of vector-like serializations, by default a range
* check is performed. When used as a generic number encoding, range_check should be set to false.
*/
template<typename Stream>
uint64_t ReadCompactSize(Stream& is)
uint64_t ReadCompactSize(Stream& is, bool range_check = true)
{
uint8_t chSize = ser_readdata8(is);
uint64_t nSizeRet = 0;
@ -331,8 +341,9 @@ uint64_t ReadCompactSize(Stream& is)
if (nSizeRet < 0x100000000ULL)
throw std::ios_base::failure("non-canonical ReadCompactSize()");
}
if (nSizeRet > (uint64_t)MAX_SIZE)
if (range_check && nSizeRet > MAX_SIZE) {
throw std::ios_base::failure("ReadCompactSize(): size too large");
}
return nSizeRet;
}
@ -466,7 +477,7 @@ static inline Wrapper<Formatter, T&> Using(T&& t) { return Wrapper<Formatter, T&
#define VARINT_MODE(obj, mode) Using<VarIntFormatter<mode>>(obj)
#define VARINT(obj) Using<VarIntFormatter<VarIntMode::DEFAULT>>(obj)
#define COMPACTSIZE(obj) Using<CompactSizeFormatter>(obj)
#define COMPACTSIZE(obj) Using<CompactSizeFormatter<true>>(obj)
#define LIMITED_STRING(obj,n) Using<LimitedStringFormatter<n>>(obj)
/** Serialization wrapper class for integers in VarInt format. */
@ -529,12 +540,13 @@ struct CustomUintFormatter
template<int Bytes> using BigEndianFormatter = CustomUintFormatter<Bytes, true>;
/** Formatter for integers in CompactSize format. */
template<bool RangeCheck>
struct CompactSizeFormatter
{
template<typename Stream, typename I>
void Unser(Stream& s, I& v)
{
uint64_t n = ReadCompactSize<Stream>(s);
uint64_t n = ReadCompactSize<Stream>(s, RangeCheck);
if (n < std::numeric_limits<I>::min() || n > std::numeric_limits<I>::max()) {
throw std::ios_base::failure("CompactSize exceeds limit of type");
}