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MP: Fix recurrent bool array compatibility issues

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When FG encounters an unknown property id in a MP packet, it discards
the remainder of the packet. This happens when adding new MP properties:
older clients will discard the property and anything that comes after.
This is normally not an issue because newer properties are placed at the
end of the packet.

However MP bool array properties (sim/generic/bool[*]) are transmitted
at the very end of a packet, meaning they get broken (for backward
compatibility) each time a property is added to the protocol.

Fix this by placing them earlier in the packet, with the same ordering
rules as other properties.
This commit is contained in:
Colin Geniet 2022-09-06 00:24:57 +02:00 • committed by James Turner
parent e6327466e6
commit 5d6ac7a1c1
1 changed files with 56 additions and 25 deletions

81
src/MultiPlayer/multiplaymgr.cxx
View file

@ -1440,6 +1440,44 @@ FGMultiplayMgr::SendMyPosition(const FGExternalMotionData& motionInfo)
struct BoolArrayBuffer boolBuffer[MAX_BOOL_BUFFERS];
memset(&boolBuffer, 0, sizeof(boolBuffer));
/* Read BOOLARRAY properties.
*
* All properties contained in a bool array must be read before adding it to the packet.
* Earlier versions of this code read the properties in the main loop below,
* and added the bool array at the very end of the packet.
* This causes bool arrays to break whenever a new MP property is added:
* older client will stop reading the packet when encountering the new property,
* and never get to the bool array.
*
* Instead, read all properties early and send the array in the main loop.
*/
std::vector<FGPropertyData*>::const_iterator it = motionInfo.properties.begin();
while (it != motionInfo.properties.end()) {
switch (mPropertyDefinition[(*it)->id]->TransmitAs) {
case TT_BOOLARRAY:
{
struct BoolArrayBuffer *boolBuf = nullptr;
if ((*it)->id >= BOOLARRAY_START_ID && (*it)->id <= BOOLARRAY_END_ID + BOOLARRAY_BLOCKSIZE)
{
int buffer_block = ((*it)->id - BOOLARRAY_BASE_1) / BOOLARRAY_BLOCKSIZE;
boolBuf = &boolBuffer[buffer_block];
boolBuf->propertyId = BOOLARRAY_START_ID + buffer_block * BOOLARRAY_BLOCKSIZE;
}
if (boolBuf)
{
int bitidx = (*it)->id - boolBuf->propertyId;
if ((*it)->int_value)
boolBuf->boolValue |= 1 << bitidx;
}
break;
}
default:
break;
}
++it;
}
for (int partition = 1; partition <= protocolToUse; partition++)
{
std::vector<FGPropertyData*>::const_iterator it = motionInfo.properties.begin();
@ -1550,19 +1588,28 @@ FGMultiplayMgr::SendMyPosition(const FGExternalMotionData& motionInfo)
}
case TT_BOOLARRAY:
{
struct BoolArrayBuffer *boolBuf = nullptr;
if ((*it)->id >= BOOLARRAY_START_ID && (*it)->id <= BOOLARRAY_END_ID + BOOLARRAY_BLOCKSIZE)
int boolIdx = ((*it)->id - BOOLARRAY_BASE_1) / BOOLARRAY_BLOCKSIZE;
if (boolIdx < 0 || boolIdx >= MAX_BOOL_BUFFERS)
{
int buffer_block = ((*it)->id - BOOLARRAY_BASE_1) / BOOLARRAY_BLOCKSIZE;
boolBuf = &boolBuffer[buffer_block];
boolBuf->propertyId = BOOLARRAY_START_ID + buffer_block * BOOLARRAY_BLOCKSIZE;
SG_LOG(SG_NETWORK, SG_WARN, "Unexpected prop id with type TT_BOOLARRAY: " << (*it)->id);
break;
}
if (boolBuf)
if (!boolBuffer[boolIdx].propertyId)
{
int bitidx = (*it)->id - boolBuf->propertyId;
if ((*it)->int_value)
boolBuf->boolValue |= 1 << bitidx;
// propertyId being unset indicates that this block was already written
break;
}
if (ptr + 2 >= msgEnd)
{
SG_LOG(SG_NETWORK, SG_ALERT, "Multiplayer packet truncated prop id: " << boolBuffer[boolIdx].propertyId << ": multiplay/generic/bools[" << boolIdx * 30 << "]");
}
*ptr++ = XDR_encode_int32(boolBuffer[boolIdx].propertyId);
*ptr++ = XDR_encode_int32(boolBuffer[boolIdx].boolValue);
boolBuffer[boolIdx].propertyId = 0; // mark block as written
break;
}
case simgear::props::INT:
@ -1711,22 +1758,6 @@ FGMultiplayMgr::SendMyPosition(const FGExternalMotionData& motionInfo)
}
escape:
/*
* Send the boolean arrays (if present) as single 32bit integers.
*/
for (int boolIdx = 0; boolIdx < MAX_BOOL_BUFFERS; boolIdx++)
{
if (boolBuffer[boolIdx].propertyId)
{
if (ptr + 2 >= msgEnd)
{
SG_LOG(SG_NETWORK, SG_ALERT, "Multiplayer packet truncated prop id: " << boolBuffer[boolIdx].propertyId << ": multiplay/generic/bools[" << boolIdx * 30 << "]");
}
*ptr++ = XDR_encode_int32(boolBuffer[boolIdx].propertyId);
*ptr++ = XDR_encode_int32(boolBuffer[boolIdx].boolValue);
}
}
msgLen = reinterpret_cast<char*>(ptr) - msgBuf.Msg;
FillMsgHdr(msgBuf.msgHdr(), POS_DATA_ID, msgLen);