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better handle corrupt packets that would cause unreasonably deep recursion

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This commit is contained in:
ZappoMan 2014-11-13 22:26:18 -08:00
parent 5da0d1e55a
commit 744f9bc508
4 changed files with 36 additions and 23 deletions
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52
libraries/octree/src/Octree.cpp
View file

@ -231,8 +231,18 @@ OctreeElement* Octree::nodeForOctalCode(OctreeElement* ancestorElement,
}
// returns the element created!
OctreeElement* Octree::createMissingElement(OctreeElement* lastParentElement, const unsigned char* codeToReach) {
OctreeElement* Octree::createMissingElement(OctreeElement* lastParentElement, const unsigned char* codeToReach, int recursionCount) {
if (recursionCount > DANGEROUSLY_DEEP_RECURSION) {
static QString repeatedMessage
= LogHandler::getInstance().addRepeatedMessageRegex(
"Octree::createMissingElement\\(\\) reached DANGEROUSLY_DEEP_RECURSION, bailing!");
qDebug() << "Octree::createMissingElement() reached DANGEROUSLY_DEEP_RECURSION, bailing!";
return lastParentElement;
}
int indexOfNewChild = branchIndexWithDescendant(lastParentElement->getOctalCode(), codeToReach);
// If this parent element is a leaf, then you know the child path doesn't exist, so deal with
// breaking up the leaf first, which will also create a child path
if (lastParentElement->requiresSplit()) {
@ -246,7 +256,7 @@ OctreeElement* Octree::createMissingElement(OctreeElement* lastParentElement, co
if (*lastParentElement->getChildAtIndex(indexOfNewChild)->getOctalCode() == *codeToReach) {
return lastParentElement->getChildAtIndex(indexOfNewChild);
} else {
return createMissingElement(lastParentElement->getChildAtIndex(indexOfNewChild), codeToReach);
return createMissingElement(lastParentElement->getChildAtIndex(indexOfNewChild), codeToReach, recursionCount + 1);
}
}
@ -255,25 +265,20 @@ int Octree::readElementData(OctreeElement* destinationElement, const unsigned ch
int bytesLeftToRead = bytesAvailable;
int bytesRead = 0;
bool wantDebug = false;
// give this destination element the child mask from the packet
const unsigned char ALL_CHILDREN_ASSUMED_TO_EXIST = 0xFF;
if ((size_t)bytesLeftToRead < sizeof(unsigned char)) {
if (wantDebug) {
qDebug() << "UNEXPECTED: readElementData() only had " << bytesLeftToRead << " bytes. "
"Not enough for meaningful data.";
}
qDebug() << "UNEXPECTED: readElementData() only had " << bytesLeftToRead << " bytes. "
"Not enough for meaningful data.";
return bytesAvailable; // assume we read the entire buffer...
}
if (destinationElement->getScale() < SCALE_AT_DANGEROUSLY_DEEP_RECURSION) {
if (wantDebug) {
qDebug() << "UNEXPECTED: readElementData() destination element is unreasonably small ["
<< destinationElement->getScale() * (float)TREE_SCALE << " meters] "
<< " Discarding " << bytesAvailable << " remaining bytes.";
}
qDebug() << "UNEXPECTED: readElementData() destination element is unreasonably small ["
<< destinationElement->getScale() * (float)TREE_SCALE << " meters] "
<< " Discarding " << bytesAvailable << " remaining bytes.";
return bytesAvailable; // assume we read the entire buffer...
}
@ -322,7 +327,7 @@ int Octree::readElementData(OctreeElement* destinationElement, const unsigned ch
: sizeof(childInBufferMask);
if (bytesLeftToRead < bytesForMasks) {
if (wantDebug) {
if (bytesLeftToRead > 0) {
qDebug() << "UNEXPECTED: readElementDataFromBuffer() only had " << bytesLeftToRead << " bytes before masks. "
"Not enough for meaningful data.";
}
@ -385,7 +390,6 @@ void Octree::readBitstreamToTree(const unsigned char * bitstream, unsigned long
ReadBitstreamToTreeParams& args) {
int bytesRead = 0;
const unsigned char* bitstreamAt = bitstream;
bool wantDebug = false;
// If destination element is not included, set it to root
if (!args.destinationElement) {
@ -398,14 +402,24 @@ void Octree::readBitstreamToTree(const unsigned char * bitstream, unsigned long
while (bitstreamAt < bitstream + bufferSizeBytes) {
OctreeElement* bitstreamRootElement = nodeForOctalCode(args.destinationElement, (unsigned char *)bitstreamAt, NULL);
int numberOfThreeBitSectionsInStream = numberOfThreeBitSectionsInCode(bitstreamAt, bufferSizeBytes);
if (numberOfThreeBitSectionsInStream > UNREASONABLY_DEEP_RECURSION) {
static QString repeatedMessage
= LogHandler::getInstance().addRepeatedMessageRegex(
"UNEXPECTED: parsing of the octal code would make UNREASONABLY_DEEP_RECURSION... "
"numberOfThreeBitSectionsInStream: \\d+ This buffer is corrupt. Returning."
);
qDebug() << "UNEXPECTED: parsing of the octal code would make UNREASONABLY_DEEP_RECURSION... "
"numberOfThreeBitSectionsInStream:" << numberOfThreeBitSectionsInStream <<
"This buffer is corrupt. Returning.";
return;
}
if (numberOfThreeBitSectionsInStream == OVERFLOWED_OCTCODE_BUFFER) {
if (wantDebug) {
qDebug() << "UNEXPECTED: parsing of the octal code would overflow the buffer. "
"This buffer is corrupt. Returning.";
}
qDebug() << "UNEXPECTED: parsing of the octal code would overflow the buffer. "
"This buffer is corrupt. Returning.";
return;
}

2
libraries/octree/src/Octree.h
View file

@ -373,7 +373,7 @@ protected:
static bool countOctreeElementsOperation(OctreeElement* element, void* extraData);
OctreeElement* nodeForOctalCode(OctreeElement* ancestorElement, const unsigned char* needleCode, OctreeElement** parentOfFoundElement) const;
OctreeElement* createMissingElement(OctreeElement* lastParentElement, const unsigned char* codeToReach);
OctreeElement* createMissingElement(OctreeElement* lastParentElement, const unsigned char* codeToReach, int recursionCount = 0);
int readElementData(OctreeElement *destinationElement, const unsigned char* nodeData,
int bufferSizeBytes, ReadBitstreamToTreeParams& args);

3
libraries/octree/src/OctreeConstants.h
View file

@ -35,10 +35,11 @@ const int MAX_TREE_SLICE_BYTES = 26;
const float VIEW_FRUSTUM_FOV_OVERSEND = 60.0f;
// These are guards to prevent our voxel tree recursive routines from spinning out of control
const int UNREASONABLY_DEEP_RECURSION = 20; // use this for something that you want to be shallow, but not spin out
const int UNREASONABLY_DEEP_RECURSION = 29; // use this for something that you want to be shallow, but not spin out
const int DANGEROUSLY_DEEP_RECURSION = 200; // use this for something that needs to go deeper
const float SCALE_AT_UNREASONABLY_DEEP_RECURSION = (1.0f / powf(2.0f, UNREASONABLY_DEEP_RECURSION));
const float SCALE_AT_DANGEROUSLY_DEEP_RECURSION = (1.0f / powf(2.0f, DANGEROUSLY_DEEP_RECURSION));
const float SMALLEST_REASONABLE_OCTREE_ELEMENT_SCALE = SCALE_AT_UNREASONABLY_DEEP_RECURSION * 2.0f; // 0.00006103515 meter ~1/10,0000th
const int DEFAULT_MAX_OCTREE_PPS = 600; // the default maximum PPS we think any octree based server should send to a client

2
libraries/octree/src/OctreeElement.h
View file

@ -36,8 +36,6 @@ class ReadBitstreamToTreeParams;
class Shape;
class VoxelSystem;
const float SMALLEST_REASONABLE_OCTREE_ELEMENT_SCALE = (1.0f / TREE_SCALE) / 10000.0f; // 1/10,000th of a meter
// Callers who want delete hook callbacks should implement this class
class OctreeElementDeleteHook {
public: