/*
* Copyright 2014 Google Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Reflection;using System.Collections.Generic;
using System.IO;
namespace Google.FlatBuffers
{
/// <summary>
/// The Class of the Verifier Options
/// </summary>
public class Options
{
public const int DEFAULT_MAX_DEPTH = 64;
public const int DEFAULT_MAX_TABLES = 1000000;
private int max_depth = 0;
private int max_tables = 0;
private bool string_end_check = false;
private bool alignment_check = false;
public Options()
{
max_depth = DEFAULT_MAX_DEPTH;
max_tables = DEFAULT_MAX_TABLES;
string_end_check = true;
alignment_check = true;
}
public Options(int maxDepth, int maxTables, bool stringEndCheck, bool alignmentCheck)
{
max_depth = maxDepth;
max_tables = maxTables;
string_end_check = stringEndCheck;
alignment_check = alignmentCheck;
}
/// <summary> Maximum depth of nested tables allowed in a valid flatbuffer. </summary>
public int maxDepth
{
get { return max_depth; }
set { max_depth = value; }
}
/// <summary> Maximum number of tables allowed in a valid flatbuffer. </summary>
public int maxTables
{
get { return max_tables; }
set { max_tables = value; }
}
/// <summary> Check that string contains its null terminator </summary>
public bool stringEndCheck
{
get { return string_end_check; }
set { string_end_check = value; }
}
/// <summary> Check alignment of elements </summary>
public bool alignmentCheck
{
get { return alignment_check; }
set { alignment_check = value; }
}
}
public struct checkElementStruct
{
public bool elementValid;
public uint elementOffset;
}
public delegate bool VerifyTableAction(Verifier verifier, uint tablePos);
public delegate bool VerifyUnionAction(Verifier verifier, byte typeId, uint tablePos);
/// <summary>
/// The Main Class of the FlatBuffer Verifier
/// </summary>
public class Verifier
{
private ByteBuffer verifier_buffer = null;
private Options verifier_options = null;
private int depth_cnt = 0;
private int num_tables_cnt = 0;
public const int SIZE_BYTE = 1;
public const int SIZE_INT = 4;
public const int SIZE_U_OFFSET = 4;
public const int SIZE_S_OFFSET = 4;
public const int SIZE_V_OFFSET = 2;
public const int SIZE_PREFIX_LENGTH = FlatBufferConstants.SizePrefixLength; // default size = 4
public const int FLATBUFFERS_MAX_BUFFER_SIZE = System.Int32.MaxValue; // default size = 2147483647
public const int FILE_IDENTIFIER_LENGTH = FlatBufferConstants.FileIdentifierLength; // default size = 4
/// <summary> The Base Constructor of the Verifier object </summary>
public Verifier()
{
// Verifier buffer
verifier_buffer = null;
// Verifier settings
verifier_options = null;
// Depth counter
depth_cnt = 0;
// Tables counter
num_tables_cnt = 0;
}
/// <summary> The Constructor of the Verifier object with input parameters: ByteBuffer and/or Options </summary>
/// <param name="buf"> Input flat byte buffer defined as ByteBuffer type</param>
/// <param name="options"> Options object with settings for the coniguration the Verifier </param>
public Verifier(ByteBuffer buf, Options options = null)
{
verifier_buffer = buf;
verifier_options = options ?? new Options();
depth_cnt = 0;
num_tables_cnt = 0;
}
/// <summary> Bytes Buffer for Verify</summary>
public ByteBuffer Buf
{
get { return verifier_buffer; }
set { verifier_buffer = value; }
}
/// <summary> Options of the Verifier </summary>
public Options options
{
get { return verifier_options; }
set { verifier_options = value; }
}
/// <summary> Counter of tables depth in a tested flatbuffer </summary>
public int depth
{
get { return depth_cnt; }
set { depth_cnt = value; }
}
/// <summary> Counter of tables in a tested flatbuffer </summary>
public int numTables
{
get { return num_tables_cnt; }
set { num_tables_cnt = value; }
}
/// <summary> Method set maximum tables depth of valid structure</summary>
/// <param name="value"> Specify Value of the maximum depth of the structure</param>
public Verifier SetMaxDepth(int value)
{
verifier_options.maxDepth = value;
return this;
}
/// <summary> Specify maximum number of tables in structure </summary>
/// <param name="value"> Specify Value of the maximum number of the tables in the structure</param>
public Verifier SetMaxTables(int value)
{
verifier_options.maxTables = value;
return this;
}
/// <summary> Enable/disable buffer content alignment check </summary>
/// <param name="value"> Value of the State for buffer content alignment check (Enable = true) </param>
public Verifier SetAlignmentCheck(bool value)
{
verifier_options.alignmentCheck = value;
return this;
}
/// <summary> Enable/disable checking of string termination '0' character </summary>
/// <param name="value"> Value of the option for string termination '0' character check (Enable = true)</param>
public Verifier SetStringCheck(bool value)
{
verifier_options.stringEndCheck = value;
return this;
}
/// <summary> Check if there is identifier in buffer </summary>
/// <param name="buf"> Input flat byte buffer defined as ByteBuffer type </param>
/// <param name="startPos">Start position of data in the Byte Buffer</param>
/// <param name="identifier"> Identifier for the Byte Buffer</param>
/// <returns> Return True when the Byte Buffer Identifier is present</returns>
private bool BufferHasIdentifier(ByteBuffer buf, uint startPos, string identifier)
{
if (identifier.Length != FILE_IDENTIFIER_LENGTH)
{
throw new ArgumentException("FlatBuffers: file identifier must be length" + Convert.ToString(FILE_IDENTIFIER_LENGTH));
}
for (int i = 0; i < FILE_IDENTIFIER_LENGTH; i++)
{
if ((sbyte)identifier[i] != verifier_buffer.GetSbyte(Convert.ToInt32(SIZE_S_OFFSET + i + startPos)))
{
return false;
}
}
return true;
}
/// <summary> Get UOffsetT from buffer at given position - it must be verified before read </summary>
/// <param name="buf"> Input flat byte buffer defined as ByteBuffer type </param>
/// <param name="pos"> Position of data in the Byte Buffer</param>
/// <returns> Return the UOffset Value (Unsigned Integer type - 4 bytes) in pos </returns>
private uint ReadUOffsetT(ByteBuffer buf, uint pos)
{
return buf.GetUint(Convert.ToInt32(pos));
}
/// <summary> Get SOffsetT from buffer at given position - it must be verified before read </summary>
/// <param name="buf"> Input flat byte buffer defined as ByteBuffer type </param>
/// <param name="pos"> Position of data in the Byte Buffer</param>
/// <returns> Return the SOffset Value (Signed Integer type - 4 bytes) in pos </returns>
private int ReadSOffsetT(ByteBuffer buf, int pos)
{
return buf.GetInt(pos);
}
/// <summary> Get VOffsetT from buffer at given position - it must be verified before read </summary>
/// <param name="buf"> Input flat byte buffer defined as ByteBuffer type </param>
/// <param name="pos"> Position of data in the Byte Buffer</param>
/// <returns> Return the VOffset Value (Short type - 2 bytes) in pos </returns>
private short ReadVOffsetT(ByteBuffer buf, int pos)
{
return buf.GetShort(pos);
}
/// <summary> Get table data area relative offset from vtable. Result is relative to table start
/// Fields which are deprecated are ignored by checking against the vtable's length. </summary>
/// <param name="pos"> Position of data in the Byte Buffer </param>
/// <param name="vtableOffset"> offset of value in the Table</param>
/// <returns> Return the relative VOffset Value (Short type - 2 bytes) in calculated offset </returns>
private short GetVRelOffset(int pos, short vtableOffset)
{
short VOffset = 0;
// Used try/catch because pos typa as int 32bit
try
{
// First, get vtable offset
short vtable = Convert.ToInt16(pos - ReadSOffsetT(verifier_buffer, pos));
// Check that offset points to vtable area (is smaller than vtable size)
if (vtableOffset < ReadVOffsetT(verifier_buffer, vtable))
{
// Now, we can read offset value - TODO check this value against size of table data
VOffset = ReadVOffsetT(verifier_buffer, vtable + vtableOffset);
}
else
{
VOffset = 0;
}
}
catch (Exception e)
{
Console.WriteLine("Exception: {0}", e);
return VOffset;
}
return VOffset;
}
/// <summary> Get table data area absolute offset from vtable. Result is the absolute buffer offset.
/// The result value offset cannot be '0' (pointing to itself) so after validation this method returnes '0'
/// value as a marker for missing optional entry </summary>
/// <param name="tablePos"> Table Position value in the Byte Buffer </param>
/// <param name="vtableOffset"> offset value in the Table</param>
/// <returns> Return the absolute UOffset Value </returns>
private uint GetVOffset(uint tablePos, short vtableOffset)
{
uint UOffset = 0;
// First, get vtable relative offset
short relPos = GetVRelOffset(Convert.ToInt32(tablePos), vtableOffset);
if (relPos != 0)
{
// Calculate offset based on table postion
UOffset = Convert.ToUInt32(tablePos + relPos);
}
else
{
UOffset = 0;
}
return UOffset;
}
/// <summary> Check flatbuffer complexity (tables depth, elements counter and so on) </summary>
/// <returns> If complexity is too high function returns false as verification error </returns>
private bool CheckComplexity()
{
return ((depth <= options.maxDepth) && (numTables <= options.maxTables));
}
/// <summary> Check alignment of element. </summary>
/// <returns> Return True when alignment of the element is correct</returns>
private bool CheckAlignment(uint element, ulong align)
{
return (((element & (align - 1)) == 0) || (!options.alignmentCheck));
}
/// <summary> Check if element is valid in buffer area. </summary>
/// <param name="pos"> Value defines the offset/position to element</param>
/// <param name="elementSize"> Size of element</param>
/// <returns> Return True when Element is correct </returns>
private bool CheckElement(uint pos, ulong elementSize)
{
return ((elementSize < Convert.ToUInt64(verifier_buffer.Length)) && (pos <= (Convert.ToUInt32(verifier_buffer.Length) - elementSize)));
}
/// <summary> Check if element is a valid scalar. </summary>
/// <param name="pos"> Value defines the offset to scalar</param>
/// <param name="elementSize"> Size of element</param>
/// <returns> Return True when Scalar Element is correct </returns>
private bool CheckScalar(uint pos, ulong elementSize)
{
return ((CheckAlignment(pos, elementSize)) && (CheckElement(pos, elementSize)));
}
/// <summary> Check offset. It is a scalar with size of UOffsetT. </summary>
private bool CheckOffset(uint offset)
{
return (CheckScalar(offset, SIZE_U_OFFSET));
}
private checkElementStruct CheckVectorOrString(uint pos, ulong elementSize)
{
var result = new checkElementStruct
{
elementValid = false,
elementOffset = 0
};
uint vectorPos = pos;
// Check we can read the vector/string size field (it is of uoffset size)
if (!CheckScalar(vectorPos, SIZE_U_OFFSET))
{
// result.elementValid = false; result.elementOffset = 0;
return result;
}
// Check the whole array. If this is a string, the byte past the array
// must be 0.
uint size = ReadUOffsetT(verifier_buffer, vectorPos);
ulong max_elements = (FLATBUFFERS_MAX_BUFFER_SIZE / elementSize);
if (size >= max_elements)
{
// Protect against byte_size overflowing.
// result.elementValid = false; result.elementOffset = 0;
return result;
}
uint bytes_size = SIZE_U_OFFSET + (Convert.ToUInt32(elementSize) * size);
uint buffer_end_pos = vectorPos + bytes_size;
result.elementValid = CheckElement(vectorPos, bytes_size);
result.elementOffset = buffer_end_pos;
return (result);
}
/// <summary>Verify a string at given position.</summary>
private bool CheckString(uint pos)
{
var result = CheckVectorOrString(pos, SIZE_BYTE);
if (options.stringEndCheck)
{
result.elementValid = result.elementValid && CheckScalar(result.elementOffset, 1); // Must have terminator
result.elementValid = result.elementValid && (verifier_buffer.GetSbyte(Convert.ToInt32(result.elementOffset)) == 0); // Terminating byte must be 0.
}
return result.elementValid;
}
/// <summary> Verify the vector of elements of given size </summary>
private bool CheckVector(uint pos, ulong elementSize)
{
var result = CheckVectorOrString(pos, elementSize);
return result.elementValid;
}
/// <summary> Verify table content using structure dependent generated function </summary>
private bool CheckTable(uint tablePos, VerifyTableAction verifyAction)
{
return verifyAction(this, tablePos);
}
/// <summary> String check wrapper function to be used in vector of strings check </summary>
private bool CheckStringFunc(Verifier verifier, uint pos)
{
return verifier.CheckString(pos);
}
/// <summary> Check vector of objects. Use generated object verification function </summary>
private bool CheckVectorOfObjects(uint pos, VerifyTableAction verifyAction)
{
if (!CheckVector(pos, SIZE_U_OFFSET))
{
return false;
}
uint size = ReadUOffsetT(verifier_buffer, pos);
// Vector data starts just after vector size/length
uint vecStart = pos + SIZE_U_OFFSET;
uint vecOff = 0;
// Iterate offsets and verify referenced objects
for (uint i = 0; i < size; i++)
{
vecOff = vecStart + (i * SIZE_U_OFFSET);
if (!CheckIndirectOffset(vecOff))
{
return false;
}
uint objOffset = GetIndirectOffset(vecOff);
if (!verifyAction(this, objOffset))
{
return false;
}
}
return true;
}
/// <summary> Check if the offset referenced by offsetPos is the valid offset pointing to buffer</summary>
// offsetPos - offset to offset data
private bool CheckIndirectOffset(uint pos)
{
// Check the input offset is valid
if(!CheckScalar(pos, SIZE_U_OFFSET))
{
return false;
}
// Get indirect offset
uint offset = ReadUOffsetT(verifier_buffer, pos);
// May not point to itself neither wrap around (buffers are max 2GB)
if ((offset == 0) || (offset >= FLATBUFFERS_MAX_BUFFER_SIZE))
{
return false;
}
// Must be inside the buffer
return CheckElement(pos + offset, 1);
}
/// <summary> Check flatbuffer content using generated object verification function </summary>
private bool CheckBufferFromStart(string identifier, uint startPos, VerifyTableAction verifyAction)
{
if ((identifier != null) &&
(identifier.Length == 0) &&
((verifier_buffer.Length < (SIZE_U_OFFSET + FILE_IDENTIFIER_LENGTH)) || (!BufferHasIdentifier(verifier_buffer, startPos, identifier))))
{
return false;
}
if(!CheckIndirectOffset(startPos))
{
return false;
}
uint offset = GetIndirectOffset(startPos);
return CheckTable(offset, verifyAction); // && GetComputedSize()
}
/// <summary> Get indirect offset. It is an offset referenced by offset Pos </summary>
private uint GetIndirectOffset(uint pos)
{
// Get indirect offset referenced by offsetPos
uint offset = pos + ReadUOffsetT(verifier_buffer, pos);
return offset;
}
/// <summary> Verify beginning of table </summary>
/// <param name="tablePos"> Position in the Table </param>
/// <returns> Return True when the verification of the beginning of the table is passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyTableStart(uint tablePos)
{
// Starting new table verification increases complexity of structure
depth_cnt++;
num_tables_cnt++;
if (!CheckScalar(tablePos, SIZE_S_OFFSET))
{
return false;
}
uint vtable = (uint)(tablePos - ReadSOffsetT(verifier_buffer, Convert.ToInt32(tablePos)));
return ((CheckComplexity()) && (CheckScalar(vtable, SIZE_V_OFFSET)) && (CheckAlignment(Convert.ToUInt32(ReadVOffsetT(verifier_buffer, Convert.ToInt32(vtable))), SIZE_V_OFFSET)) && (CheckElement(vtable, Convert.ToUInt64(ReadVOffsetT(verifier_buffer, Convert.ToInt32(vtable))))));
}
/// <summary> Verify end of table. In practice, this function does not check buffer but handles
/// verification statistics update </summary>
// (this method is used internally by generated verification functions)
public bool VerifyTableEnd(uint tablePos)
{
depth--;
return true;
}
/// <summary> Verifiy static/inlined data area field </summary>
/// <param name="tablePos"> Position in the Table</param>
/// <param name="offsetId"> Offset to the static/inlined data element </param>
/// <param name="elementSize"> Size of the element </param>
/// <param name="align"> Alignment bool value </param>
/// <param name="required"> Required Value when the offset == 0 </param>
/// <returns>Return True when the verification of the static/inlined data element is passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyField(uint tablePos, short offsetId, ulong elementSize, ulong align, bool required)
{
uint offset = GetVOffset(tablePos, offsetId);
if (offset != 0)
{
return ((CheckAlignment(offset, align)) && (CheckElement(offset, elementSize)));
}
return !required; // it is OK if field is not required
}
/// <summary> Verify string </summary>
/// <param name="tablePos"> Position in the Table</param>
/// <param name="vOffset"> Offset to the String element </param>
/// <param name="required"> Required Value when the offset == 0 </param>
/// <returns>Return True when the verification of the String is passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyString(uint tablePos, short vOffset, bool required)
{
var offset = GetVOffset(tablePos, vOffset);
if (offset == 0)
{
return !required;
}
if (!CheckIndirectOffset(offset))
{
return false;
}
var strOffset = GetIndirectOffset(offset);
return CheckString(strOffset);
}
/// <summary> Verify vector of fixed size structures and scalars </summary>
/// <param name="tablePos"> Position in the Table</param>
/// <param name="vOffset"> Offset to the Vector of Data </param>
/// <param name="elementSize"> Size of the element</param>
/// <param name="required"> Required Value when the offset == 0 </param>
/// <returns>Return True when the verification of the Vector of Data passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyVectorOfData(uint tablePos, short vOffset, ulong elementSize, bool required)
{
var offset = GetVOffset(tablePos, vOffset);
if (offset == 0)
{
return !required;
}
if (!CheckIndirectOffset(offset))
{
return false;
}
var vecOffset = GetIndirectOffset(offset);
return CheckVector(vecOffset, elementSize);
}
/// <summary> Verify array of strings </summary>
/// <param name="tablePos"> Position in the Table</param>
/// <param name="offsetId"> Offset to the Vector of String </param>
/// <param name="required"> Required Value when the offset == 0 </param>
/// <returns>Return True when the verification of the Vector of String passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyVectorOfStrings(uint tablePos, short offsetId, bool required)
{
var offset = GetVOffset(tablePos, offsetId);
if (offset == 0)
{
return !required;
}
if (!CheckIndirectOffset(offset))
{
return false;
}
var vecOffset = GetIndirectOffset(offset);
return CheckVectorOfObjects(vecOffset, CheckStringFunc);
}
/// <summary> Verify vector of tables (objects). Tables are verified using generated verifyObjFunc </summary>
/// <param name="tablePos"> Position in the Table</param>
/// <param name="offsetId"> Offset to the Vector of Table </param>
/// <param name="verifyAction"> Method used to the verification Table </param>
/// <param name="required"> Required Value when the offset == 0 </param>
/// <returns>Return True when the verification of the Vector of Table passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyVectorOfTables(uint tablePos, short offsetId, VerifyTableAction verifyAction, bool required)
{
var offset = GetVOffset(tablePos, offsetId);
if (offset == 0)
{
return !required;
}
if (!CheckIndirectOffset(offset))
{
return false;
}
var vecOffset = GetIndirectOffset(offset);
return CheckVectorOfObjects(vecOffset, verifyAction);
}
/// <summary> Verify table object using generated verification function. </summary>
/// <param name="tablePos"> Position in the Table</param>
/// <param name="offsetId"> Offset to the Table </param>
/// <param name="verifyAction"> Method used to the verification Table </param>
/// <param name="required"> Required Value when the offset == 0 </param>
/// <returns>Return True when the verification of the Table passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyTable(uint tablePos, short offsetId, VerifyTableAction verifyAction, bool required)
{
var offset = GetVOffset(tablePos, offsetId);
if (offset == 0)
{
return !required;
}
if (!CheckIndirectOffset(offset))
{
return false;
}
var tabOffset = GetIndirectOffset(offset);
return CheckTable(tabOffset, verifyAction);
}
/// <summary> Verify nested buffer object. When verifyObjFunc is provided, it is used to verify object structure. </summary>
/// <param name="tablePos"> Position in the Table </param>
/// <param name="offsetId"> Offset to the Table </param>
/// <param name="verifyAction"> Method used to the verification Table </param>
/// <param name="required"> Required Value when the offset == 0 </param>
// (this method is used internally by generated verification functions)
public bool VerifyNestedBuffer(uint tablePos, short offsetId, VerifyTableAction verifyAction, bool required)
{
var offset = GetVOffset(tablePos, offsetId);
if (offset == 0)
{
return !required;
}
uint vecOffset = GetIndirectOffset(offset);
if (!CheckVector(vecOffset, SIZE_BYTE))
{
return false;
}
if (verifyAction != null)
{
var vecLength = ReadUOffsetT(verifier_buffer, vecOffset);
// Buffer begins after vector length
var vecStart = vecOffset + SIZE_U_OFFSET;
// Create and Copy nested buffer bytes from part of Verify Buffer
var nestedByteBuffer = new ByteBuffer(verifier_buffer.ToArray(Convert.ToInt32(vecStart), Convert.ToInt32(vecLength)));
var nestedVerifyier = new Verifier(nestedByteBuffer, options);
// There is no internal identifier - use empty one
if (!nestedVerifyier.CheckBufferFromStart("", 0, verifyAction))
{
return false;
}
}
return true;
}
/// <summary> Verifiy static/inlined data area at absolute offset </summary>
/// <param name="pos"> Position of static/inlined data area in the Byte Buffer</param>
/// <param name="elementSize"> Size of the union data</param>
/// <param name="align"> Alignment bool value </param>
/// <returns>Return True when the verification of the Union Data is passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyUnionData(uint pos, ulong elementSize, ulong align)
{
bool result = ((CheckAlignment(pos, align)) && (CheckElement(pos, elementSize)));
return result;
}
/// <summary> Verify string referenced by absolute offset value </summary>
/// <param name="pos"> Position of Union String in the Byte Buffer</param>
/// <returns>Return True when the verification of the Union String is passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyUnionString(uint pos)
{
bool result = CheckString(pos);
return result;
}
/// <summary> Method verifies union object using generated verification function </summary>
/// <param name="tablePos"> Position in the Table</param>
/// <param name="typeIdVOffset"> Offset in the Table</param>
/// <param name="valueVOffset"> Offset to Element</param>
/// <param name="verifyAction"> Verification Method used for Union</param>
/// <param name="required"> Required Value when the offset == 0 </param>
// (this method is used internally by generated verification functions)
public bool VerifyUnion(uint tablePos, short typeIdVOffset, short valueVOffset, VerifyUnionAction verifyAction, bool required)
{
// Check the union type index
var offset = GetVOffset(tablePos, typeIdVOffset);
if (offset == 0)
{
return !required;
}
if (!((CheckAlignment(offset, SIZE_BYTE)) && (CheckElement(offset, SIZE_BYTE))))
{
return false;
}
// Check union data
offset = GetVOffset(tablePos, valueVOffset);
// Take type id
var typeId = verifier_buffer.Get(Convert.ToInt32(offset));
if (offset == 0)
{
// When value data is not present, allow union verification function to deal with illegal offset
return verifyAction(this, typeId, Convert.ToUInt32(verifier_buffer.Length));
}
if (!CheckIndirectOffset(offset))
{
return false;
}
// Take value offset and validate union structure
uint unionOffset = GetIndirectOffset(offset);
return verifyAction(this, typeId, unionOffset);
}
/// <summary> Verify vector of unions (objects). Unions are verified using generated verifyObjFunc </summary>
/// <param name="tablePos"> Position of the Table</param>
/// <param name="typeOffsetId"> Offset in the Table (Union type id)</param>
/// <param name="offsetId"> Offset to vector of Data Stucture offset</param>
/// <param name="verifyAction"> Verification Method used for Union</param>
/// <param name="required"> Required Value when the offset == 0 </param>
/// <returns>Return True when the verification of the Vector of Unions passed</returns>
// (this method is used internally by generated verification functions)
public bool VerifyVectorOfUnion(uint tablePos, short typeOffsetId, short offsetId, VerifyUnionAction verifyAction, bool required)
{
// type id offset must be valid
var offset = GetVOffset(tablePos, typeOffsetId);
if (offset == 0)
{
return !required;
}
if (!CheckIndirectOffset(offset))
{
return false;
}
// Get type id table absolute offset
var typeIdVectorOffset = GetIndirectOffset(offset);
// values offset must be valid
offset = GetVOffset(tablePos, offsetId);
if (!CheckIndirectOffset(offset))
{
return false;
}
var valueVectorOffset = GetIndirectOffset(offset);
// validate referenced vectors
if(!CheckVector(typeIdVectorOffset, SIZE_BYTE) ||
!CheckVector(valueVectorOffset, SIZE_U_OFFSET))
{
return false;
}
// Both vectors should have the same length
var typeIdVectorLength = ReadUOffsetT(verifier_buffer, typeIdVectorOffset);
var valueVectorLength = ReadUOffsetT(verifier_buffer, valueVectorOffset);
if (typeIdVectorLength != valueVectorLength)
{
return false;
}
// Verify each union from vectors
var typeIdStart = typeIdVectorOffset + SIZE_U_OFFSET;
var valueStart = valueVectorOffset + SIZE_U_OFFSET;
for (uint i = 0; i < typeIdVectorLength; i++)
{
// Get type id
byte typeId = verifier_buffer.Get(Convert.ToInt32(typeIdStart + i * SIZE_U_OFFSET));
// get offset to vector item
uint off = valueStart + i * SIZE_U_OFFSET;
// Check the vector item has a proper offset
if (!CheckIndirectOffset(off))
{
return false;
}
uint valueOffset = GetIndirectOffset(off);
// Verify object
if (!verifyAction(this, typeId, valueOffset))
{
return false;
}
}
return true;
}
// Method verifies flatbuffer data using generated Table verification function.
// The data buffer is already provided when creating [Verifier] object (see [NewVerifier])
//
// - identifier - the expected identifier of buffer data.
// When empty identifier is provided the identifier validation is skipped.
// - sizePrefixed - this flag should be true when buffer is prefixed with content size
// - verifyObjFunc - function to be used for verification. This function is generated by compiler and included in each table definition file with name "<Tablename>Verify"
//
// Example:
//
// /* Verify Monster table. Ignore buffer name and assume buffer does not contain data length prefix */
// isValid = verifier.verifyBuffer(bb, false, MonsterVerify)
//
// /* Verify Monster table. Buffer name is 'MONS' and contains data length prefix */
// isValid = verifier.verifyBuffer("MONS", true, MonsterVerify)
/// <summary> Method verifies flatbuffer data using generated Table verification function </summary>
///
/// <param name="identifier"> The expected identifier of buffer data</param>
/// <param name="sizePrefixed"> Flag should be true when buffer is prefixed with content size</param>
/// <param name="verifyAction"> Function to be used for verification. This function is generated by compiler and included in each table definition file</param>
/// <returns> Return True when verification of FlatBuffer passed</returns>
/// <example>
/// Example 1. Verify Monster table. Ignore buffer name and assume buffer does not contain data length prefix
/// <code> isValid = verifier.VerifyBuffer(bb, false, MonsterVerify)</code>
/// Example 2. Verify Monster table. Buffer name is 'MONS' and contains data length prefix
/// <code> isValid = verifier.VerifyBuffer("MONS", true, MonsterVerify)</code>
/// </example>
public bool VerifyBuffer(string identifier, bool sizePrefixed, VerifyTableAction verifyAction)
{
// Reset counters - starting verification from beginning
depth = 0;
numTables = 0;
var start = (uint)(verifier_buffer.Position);
if (sizePrefixed)
{
start = (uint)(verifier_buffer.Position) + SIZE_PREFIX_LENGTH;
if(!CheckScalar((uint)(verifier_buffer.Position), SIZE_PREFIX_LENGTH))
{
return false;
}
uint size = ReadUOffsetT(verifier_buffer, (uint)(verifier_buffer.Position));
if (size != ((uint)(verifier_buffer.Length) - start))
{
return false;
}
}
return CheckBufferFromStart(identifier, start, verifyAction);
}
}
}