lib/nbt: Validator: Fix bytes not being added up correctly in multiple places

I did a `#define return` and then tried to `if () return;` everywhere...

src/lib/javacompat.cpp

@@ -75,6 +75,7 @@ namespace JavaCompat {
             output.push_back(stdString[i]);
         }
 
+        //FIXME: endian-dependent implementation
         #ifdef FOSSVG_BIG_ENDIAN
             output[0] = *sizeBytes;
             output[1] = *(sizeBytes+1);
@@ -83,7 +84,7 @@ namespace JavaCompat {
                 output[0] = *(sizeBytes+1);
                 output[1] = *sizeBytes;
             #else
-                #error "NBT::helper::writeInt16: An implementation for your endianness is unavailable."
+                #error "JavaCompat::exportJavaString: An implementation for your endianness is unavailable."
             #endif
         #endif
 

src/lib/nbt.cpp

@@ -146,11 +146,16 @@ namespace NBT {
         }
 
         ErrorOr<tiny_utf8::string> readString(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
-            if(dataSize > 0xFFFF){
+            if(currentPosition > dataSize){
                 return ErrorOr<tiny_utf8::string>(true, ErrorCodes::OVERRUN);
             }
 
-            ErrorOr<tiny_utf8::string> output = JavaCompat::importJavaString(data+currentPosition, (uint16_t) dataSize);
+            ErrorOr<int16_t> stringSize = readInt16(data, dataSize, currentPosition);
+            if (stringSize.isError) {
+                return ErrorOr<tiny_utf8::string>(true, stringSize.errorCode);
+            }
+
+            ErrorOr<tiny_utf8::string> output = JavaCompat::importJavaString(data+currentPosition, stringSize.value);
             if(output.isError){
                 return ErrorOr<tiny_utf8::string>(true, output.errorCode);
             }
@@ -385,9 +390,9 @@ namespace NBT {
         // be determined easily by looking at the contained data type and
         // size information but cases like string lists or compound lists
         // are significantly more difficult to deal with. Parsing their
-        // contents requires special attention anyway due the tag headers
-        // of contained tags being absent so they may as well get their
-        // own function for this as well.
+        // contents requires special attention anyway due to the tag headers
+        // of contained tags being absent so they may as well get treated
+        // separately for this as well.
         ErrorOr<uint64_t> totalTagSize(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
             uint8_t nextTag;
             if (dataSize <= currentPosition) {
@@ -569,10 +574,247 @@ namespace NBT {
         }
     }
 
-    bool validateRawNBTData(uint8_t data[], uint64_t dataSize, uint64_t initialPosition){
-        //TODO: find out the size of the next tag
-        //TODO: consume tag
-        //TODO: recurse if tag compound and return if tag end
-        return false;
+    bool validateRawList(uint8_t data[], uint64_t dataSize, uint64_t initialPosition, uint64_t* processedDataSize) {
+        ErrorOr<int32_t> elementCount = helper::containedDataLength(data, dataSize, initialPosition);
+        if (elementCount.isError) {
+            return false;
+        }
+        // there is no way this is an error bc it gets checked while trying
+        // to get the element count
+        int16_t nameSize = helper::readInt16(data, dataSize, initialPosition+1).value;
+        // type byte + two name size bytes = 3
+        uint8_t contentType = data[initialPosition + nameSize + 3];
+        // type byte + two name size bytes + contained type byte + 4 length bytes = 8
+        *processedDataSize = (uint64_t) nameSize + 8;
+        switch (contentType) {
+            case TagType::END:
+                // everything except content has been touched at this point
+                // and a list of end tags has no content
+                return true;
+            case TagType::INT8: {
+                *processedDataSize += (uint64_t) elementCount.value;
+                return initialPosition + *processedDataSize < dataSize;
+            }
+            case TagType::INT16: {
+                *processedDataSize += (uint64_t) elementCount.value * 2;
+                return initialPosition + *processedDataSize < dataSize;
+            }
+            case TagType::INT32:
+            case TagType::FLOAT: {
+                *processedDataSize += (uint64_t) elementCount.value * 4;
+                return initialPosition + *processedDataSize < dataSize;
+            }
+            case TagType::INT64:
+            case TagType::DOUBLE: {
+                *processedDataSize += (uint64_t) elementCount.value * 8;
+                return initialPosition + *processedDataSize < dataSize;
+            }
+            case TagType::INT8_ARRAY: {
+                for (int32_t i=0; i<elementCount.value; i++) {
+                    ErrorOr<std::vector<int8_t>> nextArray = helper::readInt8Array(data, dataSize, initialPosition+*processedDataSize);
+                    if (nextArray.isError) {
+                        return false;
+                    }
+                    *processedDataSize += (uint64_t) nextArray.value.size();
+                }
+                return true;
+            }
+            case TagType::STRING: {
+                for (int32_t i=0; i<elementCount.value; i++) {
+                    ErrorOr<tiny_utf8::string> nextString = helper::readString(data, dataSize, initialPosition+*processedDataSize);
+                    if (nextString.isError) {
+                        return false;
+                    }
+                    // this cannot be an error because it just got checked
+                    int16_t nextStringSize = helper::readInt16(data, dataSize, initialPosition+*processedDataSize).value;
+                    *processedDataSize += (uint64_t) nextStringSize + 2;
+                }
+                return true;
+            }
+            case TagType::LIST: {
+                uint64_t* containedDataSize = new uint64_t;
+                for (int32_t i=0; i<elementCount.value; i++) {
+                    *containedDataSize = 0;
+                    if (validateRawList(data, dataSize, initialPosition+*processedDataSize, containedDataSize)) {
+                        *processedDataSize += *containedDataSize;
+                    } else {
+                        delete containedDataSize;
+                        return false;
+                    }
+                }
+                delete containedDataSize;
+                return true;
+            }
+            case TagType::COMPOUND: {
+                uint64_t* containedDataSize = new uint64_t;
+                for (int32_t i=0; i<elementCount.value; i++) {
+                    *containedDataSize = 0;
+                    if (validateRawNBTData(data, dataSize, initialPosition, containedDataSize)) {
+                        *processedDataSize += *containedDataSize;
+                    } else {
+                        delete containedDataSize;
+                        return false;
+                    }
+                }
+                delete containedDataSize;
+                return true;
+            }
+            case TagType::INT32_ARRAY: {
+                for (int32_t i=0; i<elementCount.value; i++) {
+                    ErrorOr<std::vector<int32_t>> nextArray = helper::readInt32Array(data, dataSize, initialPosition+*processedDataSize);
+                    if (nextArray.isError) {
+                        return false;
+                    }
+                    *processedDataSize += (uint64_t) nextArray.value.size() * 4;
+                }
+                return true;
+            }
+            case TagType::INT64_ARRAY: {
+                for (int32_t i=0; i<elementCount.value; i++) {
+                    ErrorOr<std::vector<int64_t>> nextArray = helper::readInt64Array(data, dataSize, initialPosition+*processedDataSize);
+                    if (nextArray.isError) {
+                        return false;
+                    }
+                    *processedDataSize += (uint64_t) nextArray.value.size() * 8;
+                }
+                return true;
+            }
+            default:
+                return false;
+        }
+    }
+
+    bool validateRawNBTData(uint8_t data[], uint64_t dataSize, uint64_t initialPosition, uint64_t* processedDataSize){
+        if (initialPosition >= dataSize) {
+            // Yes, this *could* return an instance of ErrorOr with
+            // ErrorCodes::OVERRUN but we only care to know if what is
+            // at that position is valid NBT which it clearly isn't according
+            // to the original spec.
+            if (processedDataSize!=nullptr) *processedDataSize=0;
+            return false;
+
+            // An interesting question at this point is whether we should
+            // consider empty input valid or invalid NBT data.
+            //
+            // The original spec says that the top-most tag is always a
+            // compound (or in more recent times, the Microsoft-commercialized
+            // in-game-purchase-enabling version also allows list tags)
+            // which automatically means that no data is invalid data...
+            // I don't see a reason why having a different tag as the top-most
+            // tag shouldn't be valid NBT in which case we have to face the
+            // question whether no data is invalid or just empty NBT data.
+            //
+            // This seems like a reasonable extension to the spec to me and
+            // it should be backwards compatible AFAIK.
+            //
+            // - BodgeMaster
+        }
+
+        uint64_t currentPosition = initialPosition;
+        #define return if (processedDataSize!=nullptr) *processedDataSize = currentPosition-initialPosition; return
+        while (currentPosition<dataSize) {
+            ErrorOr<uint64_t> nextTagSize = helper::totalTagSize(data, dataSize, currentPosition);
+            if (nextTagSize.isError) {
+                if (nextTagSize.errorCode == ErrorCodes::NOT_YET_KNOWN) {
+                    // attempt parsing the name
+                    ErrorOr<tiny_utf8::string> tagName = helper::readString(data, dataSize, currentPosition+1);
+                    if (tagName.isError) {
+                        return false;
+                    }
+
+                    uint64_t* processedTagSize = new uint64_t;
+                    *processedTagSize = 0;
+
+                    if (data[currentPosition]==TagType::LIST) {
+                        if (!validateRawList(data, dataSize, currentPosition, processedTagSize)) {
+                            delete processedTagSize;
+                            return false;
+                        }
+                    }
+                    if (data[currentPosition]==TagType::COMPOUND) {
+                        // seek to the start of the compound's contents
+                        //
+                        // there is no way this is an error bc it gets
+                        // checked while trying to parse the string above
+                        int16_t nameSize = helper::readInt16(data, dataSize, currentPosition+1).value;
+
+                        // type byte + two name size bytes = 3
+                        if (!validateRawNBTData(data, dataSize, currentPosition + (uint64_t) nameSize + 3, processedTagSize)) {
+                            delete processedTagSize;
+                            return false;
+                        }
+                        *processedTagSize += (uint64_t) nameSize + 3;
+                    }
+                    currentPosition += *processedTagSize;
+
+                    delete processedTagSize;
+                    continue;
+                }
+                return false;
+            }
+
+            if (currentPosition + nextTagSize.value > dataSize) {
+                return false;
+            }
+
+            // recursion abort condition
+            if (data[currentPosition]==TagType::END) {
+                currentPosition++;
+                return true;
+            }
+
+            // nameSize cannot be an error here bc it got checked in
+            // nextTagSize() already
+            int16_t nameSize = helper::readInt16(data, dataSize, currentPosition+1).value;
+
+            // attempt parsing the name
+            //
+            // This shouldn't matter too much here as the only error condition
+            // the parser function deals with rn is an overrun which is already
+            // being guarded against with
+            // if (currentPosition + nextTagSize.value > dataSize) return false;
+            // It might, however, turn out to be a useful check in the future.
+            ErrorOr<tiny_utf8::string> name = helper::readString(data, dataSize, currentPosition+1);
+            if (name.isError) {
+                return false;
+            }
+
+            switch (data[currentPosition]) {
+                case TagType::INT8:
+                case TagType::INT16:
+                case TagType::INT32:
+                case TagType::INT64:
+                case TagType::FLOAT:
+                case TagType::DOUBLE:
+                case TagType::INT8_ARRAY:
+                    break;
+                case TagType::STRING: {
+                    // attempt parsing the content
+                    //
+                    // This shouldn't matter too much here as the only
+                    // error condition the parser function deals with rn is
+                    // an overrun which is already being guarded against with
+                    // if (currentPosition + nextTagSize.value > dataSize) return false;
+                    // It might, however, turn out to be a useful check
+                    // in the future.
+                    //
+                    // type byte + two name size bytes = 3
+                    ErrorOr<tiny_utf8::string> content = helper::readString(data, dataSize, currentPosition+nameSize+3);
+                    if (content.isError) {
+                        return false;
+                    }
+                    break;
+                }
+                case TagType::INT32_ARRAY:
+                case TagType::INT64_ARRAY:
+                    break;
+                default:
+                    return false;
+            }
+
+            currentPosition += nextTagSize.value;
+        }
+        return true;
+        #undef return
     }
 }

src/lib/nbt.hpp

@@ -113,5 +113,5 @@ namespace NBT {
         bool validate(uint8_t data[]);
     };
 
-    bool validateRawNBTData(uint8_t data[], int length, uint64_t initialPosition=0);
+    bool validateRawNBTData(uint8_t data[], uint64_t dataSize, uint64_t initialPosition=0, uint64_t* processedDataSize=nullptr);
 }