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Fix packetbuffer handling in UDPEndPointImplOpenThread. #18851

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merged 1 commit into from
May 26, 2022
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Fix packetbuffer handling in UDPEndPointImplOpenThread. #18851

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50 changes: 32 additions & 18 deletions src/inet/UDPEndPointImplOpenThread.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,11 +32,21 @@ namespace Inet {

otInstance * globalOtInstance;

namespace {
// We want to reserve space for an IPPacketInfo in our buffer, but it needs to
// be 4-byte aligned. We ensure the alignment by masking off the low bits of
// the pointer that we get by doing `Start() - sizeof(IPPacketInfo)`. That
// might move it backward by up to kPacketInfoAlignmentBytes, so we need to make
// sure we allocate enough reserved space that this will still be within our
// buffer.
constexpr uint16_t kPacketInfoAlignmentBytes = sizeof(uint32_t) - 1;
constexpr uint16_t kPacketInfoReservedSize = sizeof(IPPacketInfo) + kPacketInfoAlignmentBytes;
} // namespace

void UDPEndPointImplOT::handleUdpReceive(void * aContext, otMessage * aMessage, const otMessageInfo * aMessageInfo)
{
UDPEndPointImplOT * ep = static_cast<UDPEndPointImplOT *>(aContext);
IPPacketInfo pktInfo;
uint16_t msgLen = otMessageGetLength(aMessage);
uint16_t msgLen = otMessageGetLength(aMessage);
System::PacketBufferHandle payload;
#if CHIP_DETAIL_LOGGING
static uint16_t msgReceivedCount = 0;
Expand All @@ -50,38 +60,43 @@ void UDPEndPointImplOT::handleUdpReceive(void * aContext, otMessage * aMessage,
return;
}

pktInfo.SrcAddress = IPAddress::FromOtAddr(aMessageInfo->mPeerAddr);
pktInfo.DestAddress = IPAddress::FromOtAddr(aMessageInfo->mSockAddr);
pktInfo.SrcPort = aMessageInfo->mPeerPort;
pktInfo.DestPort = aMessageInfo->mSockPort;

payload = System::PacketBufferHandle::New(msgLen, 0);
payload = System::PacketBufferHandle::New(msgLen, kPacketInfoReservedSize);

if (payload.IsNull())
{
ChipLogError(Inet, "Failed to allocate a System buffer of size %d for UDP Message reception.", msgLen);
return;
}

IPPacketInfo * pktInfo = GetPacketInfo(payload);
if (pktInfo == nullptr)
{
ChipLogError(Inet, "Failed to pre-allocate reserved space for an IPPacketInfo for UDP Message reception.");
return;
}

pktInfo->SrcAddress = IPAddress::FromOtAddr(aMessageInfo->mPeerAddr);
pktInfo->DestAddress = IPAddress::FromOtAddr(aMessageInfo->mSockAddr);
pktInfo->SrcPort = aMessageInfo->mPeerPort;
pktInfo->DestPort = aMessageInfo->mSockPort;

#if CHIP_DETAIL_LOGGING
pktInfo.SrcAddress.ToString(sourceStr, Inet::IPAddress::kMaxStringLength);
pktInfo.DestAddress.ToString(destStr, Inet::IPAddress::kMaxStringLength);
pktInfo->SrcAddress.ToString(sourceStr, Inet::IPAddress::kMaxStringLength);
pktInfo->DestAddress.ToString(destStr, Inet::IPAddress::kMaxStringLength);

ChipLogDetail(Inet,
"UDP Message Received packet nb : %d SrcAddr : %s[%d] DestAddr "
": %s[%d] Payload Length %d",
++msgReceivedCount, sourceStr, pktInfo.SrcPort, destStr, pktInfo.DestPort, msgLen);
++msgReceivedCount, sourceStr, pktInfo->SrcPort, destStr, pktInfo->DestPort, msgLen);

#endif

memcpy(payload->Start(), &pktInfo, sizeof(IPPacketInfo));

if (otMessageRead(aMessage, 0, payload->Start() + sizeof(IPPacketInfo), msgLen) != msgLen)
if (otMessageRead(aMessage, 0, payload->Start(), msgLen) != msgLen)
{
ChipLogError(Inet, "Failed to copy OpenThread buffer into System Packet buffer");
return;
}
payload->SetDataLength(static_cast<uint16_t>(msgLen + sizeof(IPPacketInfo)));
payload->SetDataLength(static_cast<uint16_t>(msgLen));

ep->Retain();
auto * buf = std::move(payload).UnsafeRelease();
Expand Down Expand Up @@ -160,7 +175,6 @@ void UDPEndPointImplOT::HandleDataReceived(System::PacketBufferHandle && msg)
const IPPacketInfo pktInfoCopy = *pktInfo; // copy the address info so that the app can free the
// PacketBuffer without affecting access to address info.

msg->ConsumeHead(sizeof(IPPacketInfo));
OnMessageReceived(this, std::move(msg), &pktInfoCopy);
}
else
Expand Down Expand Up @@ -279,7 +293,7 @@ CHIP_ERROR UDPEndPointImplOT::IPv6JoinLeaveMulticastGroupImpl(InterfaceId aInter

IPPacketInfo * UDPEndPointImplOT::GetPacketInfo(const System::PacketBufferHandle & aBuffer)
{
if (!aBuffer->EnsureReservedSize(sizeof(IPPacketInfo)))
if (!aBuffer->EnsureReservedSize(kPacketInfoReservedSize))
{
return nullptr;
}
Expand All @@ -288,7 +302,7 @@ IPPacketInfo * UDPEndPointImplOT::GetPacketInfo(const System::PacketBufferHandle
uintptr_t lPacketInfoStart = lStart - sizeof(IPPacketInfo);

// Align to a 4-byte boundary
return reinterpret_cast<IPPacketInfo *>(lPacketInfoStart & ~(sizeof(uint32_t) - 1));
return reinterpret_cast<IPPacketInfo *>(lPacketInfoStart & ~kPacketInfoAlignmentBytes);
}

} // namespace Inet
Expand Down