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Use adapter pattern for the network deserializer
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@jonasschnelli
jonasschnelli committed Oct 18, 2019
1 parent 1a5c656 commit efecb74
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Showing 2 changed files with 42 additions and 29 deletions.
25 changes: 10 additions & 15 deletions src/net.cpp
View file
Expand Up @@ -571,18 +571,13 @@ bool CNode::ReceiveMsgBytes(const char *pch, unsigned int nBytes, bool& complete
nRecvBytes += nBytes;
while (nBytes > 0) {
// absorb network data
int handled;
if (!m_deserializer->in_data)
handled = m_deserializer->readHeader(pch, nBytes);
else
handled = m_deserializer->readData(pch, nBytes);

int handled = m_deserializer->Read(pch, nBytes);
if (handled < 0) {
m_deserializer->Reset();
return false;
}

if (m_deserializer->in_data && m_deserializer->hdr.nMessageSize > MAX_PROTOCOL_MESSAGE_LENGTH) {
if (m_deserializer->OversizedMessageDetected()) {
LogPrint(BCLog::NET, "Oversized message from peer=%i, disconnecting\n", GetId());
m_deserializer->Reset();
return false;
Expand All @@ -591,13 +586,13 @@ bool CNode::ReceiveMsgBytes(const char *pch, unsigned int nBytes, bool& complete
pch += handled;
nBytes -= handled;

if (m_deserializer->complete()) {
if (m_deserializer->Complete()) {
// decompose a transport agnostic CNetMessage from the deserializer
CNetMessage msg = m_deserializer->GetMessage(Params().MessageStart(), nTimeMicros);

//store received bytes per message command
//to prevent a memory DOS, only allow valid commands
mapMsgCmdSize::iterator i = mapRecvBytesPerMsgCmd.find(m_deserializer->hdr.pchCommand);
mapMsgCmdSize::iterator i = mapRecvBytesPerMsgCmd.find(msg.m_command);
if (i == mapRecvBytesPerMsgCmd.end())
i = mapRecvBytesPerMsgCmd.find(NET_MESSAGE_COMMAND_OTHER);
assert(i != mapRecvBytesPerMsgCmd.end());
Expand Down Expand Up @@ -639,7 +634,7 @@ int CNode::GetSendVersion() const
return nSendVersion;
}

int TransportDeserializer::readHeader(const char *pch, unsigned int nBytes)
int V1TransportDeserializer::readHeader(const char *pch, unsigned int nBytes)
{
// copy data to temporary parsing buffer
unsigned int nRemaining = 24 - nHdrPos;
Expand Down Expand Up @@ -670,7 +665,7 @@ int TransportDeserializer::readHeader(const char *pch, unsigned int nBytes)
return nCopy;
}

int TransportDeserializer::readData(const char *pch, unsigned int nBytes)
int V1TransportDeserializer::readData(const char *pch, unsigned int nBytes)
{
unsigned int nRemaining = hdr.nMessageSize - nDataPos;
unsigned int nCopy = std::min(nRemaining, nBytes);
Expand All @@ -687,15 +682,15 @@ int TransportDeserializer::readData(const char *pch, unsigned int nBytes)
return nCopy;
}

const uint256& TransportDeserializer::GetMessageHash() const
const uint256& V1TransportDeserializer::GetMessageHash() const
{
assert(complete());
assert(Complete());
if (data_hash.IsNull())
hasher.Finalize(data_hash.begin());
return data_hash;
}

CNetMessage TransportDeserializer::GetMessage(const CMessageHeader::MessageStartChars& message_start, int64_t time) {
CNetMessage V1TransportDeserializer::GetMessage(const CMessageHeader::MessageStartChars& message_start, int64_t time) {
// decompose a single CNetMessage from the TransportDeserializer
CNetMessage msg(std::move(vRecv));

Expand Down Expand Up @@ -2708,7 +2703,7 @@ CNode::CNode(NodeId idIn, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn
LogPrint(BCLog::NET, "Added connection peer=%d\n", id);
}

m_deserializer = MakeUnique<TransportDeserializer>(TransportDeserializer(Params().MessageStart(), SER_NETWORK, INIT_PROTO_VERSION));
m_deserializer = MakeUnique<V1TransportDeserializer>(V1TransportDeserializer(Params().MessageStart(), SER_NETWORK, INIT_PROTO_VERSION));
}

CNode::~CNode()
Expand Down
46 changes: 32 additions & 14 deletions src/net.h
View file
Expand Up @@ -637,20 +637,40 @@ class CNetMessage {
* transport protocol agnostic CNetMessage (command & payload)
*/
class TransportDeserializer {
public:
// prepare for next message
virtual void Reset() = 0;
// returns true if the current deserialization is complete
virtual bool Complete() const = 0;
// checks if the potential message in deserialization is oversized
virtual bool OversizedMessageDetected() const = 0;
// set the serialization context version
virtual void SetVersion(int version) = 0;
// read and deserialize data
virtual int Read(const char *data, unsigned int bytes) = 0;
// decomposes a message from the context
virtual CNetMessage GetMessage(const CMessageHeader::MessageStartChars& message_start, int64_t time) = 0;
virtual ~TransportDeserializer() {}
};

class V1TransportDeserializer : public TransportDeserializer
{
private:
mutable CHash256 hasher;
mutable uint256 data_hash;
public:
bool in_data; // parsing header (false) or data (true)

CDataStream hdrbuf; // partially received header
CMessageHeader hdr; // complete header
unsigned int nHdrPos;

CDataStream vRecv; // received message data
unsigned int nHdrPos;
unsigned int nDataPos;

TransportDeserializer(const CMessageHeader::MessageStartChars& pchMessageStartIn, int nTypeIn, int nVersionIn) : hdrbuf(nTypeIn, nVersionIn), hdr(pchMessageStartIn), vRecv(nTypeIn, nVersionIn) {
const uint256& GetMessageHash() const;
int readHeader(const char *pch, unsigned int nBytes);
int readData(const char *pch, unsigned int nBytes);
public:

V1TransportDeserializer(const CMessageHeader::MessageStartChars& pchMessageStartIn, int nTypeIn, int nVersionIn) : hdrbuf(nTypeIn, nVersionIn), hdr(pchMessageStartIn), vRecv(nTypeIn, nVersionIn) {
Reset();
}

Expand All @@ -664,25 +684,23 @@ class TransportDeserializer {
data_hash.SetNull();
hasher.Reset();
}

bool complete() const
bool Complete() const
{
if (!in_data)
return false;
return (hdr.nMessageSize == nDataPos);
}

const uint256& GetMessageHash() const;

void SetVersion(int nVersionIn)
{
hdrbuf.SetVersion(nVersionIn);
vRecv.SetVersion(nVersionIn);
}

int readHeader(const char *pch, unsigned int nBytes);
int readData(const char *pch, unsigned int nBytes);

bool OversizedMessageDetected() const {
return (in_data && hdr.nMessageSize > MAX_PROTOCOL_MESSAGE_LENGTH);
}
int Read(const char *pch, unsigned int nBytes) {
return in_data ? readData(pch, nBytes) : readHeader(pch, nBytes);
}
CNetMessage GetMessage(const CMessageHeader::MessageStartChars& message_start, int64_t time);
};

Expand Down

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