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// bson_validate.cpp
/* Copyright 2012 10gen Inc.
*
* 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.
*/
#include <deque>
#include "mongo/bson/bson_validate.h"
#include "mongo/bson/oid.h"
namespace mongo {
namespace {
class Buffer {
public:
Buffer( const char* buffer, uint64_t maxLength )
: _buffer( buffer ), _position( 0 ), _maxLength( maxLength ) {
}
template<typename N>
bool readNumber( N* out ) {
if ( ( _position + sizeof(N) ) > _maxLength )
return false;
if ( out ) {
const N* temp = reinterpret_cast<const N*>(_buffer + _position);
*out = *temp;
}
_position += sizeof(N);
return true;
}
Status readCString( StringData* out ) {
const void* x = memchr( _buffer + _position, 0, _maxLength - _position );
if ( !x )
return Status( ErrorCodes::InvalidBSON, "no end of c-string" );
uint64_t len = static_cast<uint64_t>( static_cast<const char*>(x) - ( _buffer + _position ) );
StringData data( _buffer + _position, len );
_position += len + 1;
if ( out ) {
*out = data;
}
return Status::OK();
}
Status readUTF8String( StringData* out ) {
int sz;
if ( !readNumber<int>( &sz ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
if ( out ) {
*out = StringData( _buffer + _position, sz );
}
if ( !skip( sz - 1 ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
char c;
if ( !readNumber<char>( &c ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
if ( c != 0 )
return Status( ErrorCodes::InvalidBSON, "not null terminate string" );
return Status::OK();
}
bool skip( uint64_t sz ) {
_position += sz;
return _position < _maxLength;
}
uint64_t position() const {
return _position;
}
private:
const char* _buffer;
uint64_t _position;
uint64_t _maxLength;
};
struct ValidationState {
enum State {
BeginObj = 1,
WithinObj,
EndObj,
BeginCodeWScope,
EndCodeWScope,
Done
};
};
class ValidationObjectFrame {
public:
int startPosition() const { return _startPosition & ~(1 << 31); }
bool isCodeWithScope() const { return _startPosition & (1 << 31); }
void setStartPosition(int pos) {
_startPosition = (_startPosition & (1 << 31)) | (pos & ~(1 << 31));
}
void setIsCodeWithScope(bool isCodeWithScope) {
if (isCodeWithScope) {
_startPosition |= 1 << 31;
}
else {
_startPosition &= ~(1 << 31);
}
}
int expectedSize;
private:
int _startPosition;
};
Status validateElementInfo(Buffer* buffer, ValidationState::State* nextState) {
Status status = Status::OK();
char type;
if ( !buffer->readNumber<char>(&type) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
if ( type == EOO ) {
*nextState = ValidationState::EndObj;
return Status::OK();
}
StringData name;
status = buffer->readCString( &name );
if ( !status.isOK() )
return status;
switch ( type ) {
case MinKey:
case MaxKey:
case jstNULL:
case Undefined:
return Status::OK();
case jstOID:
if ( !buffer->skip( sizeof(OID) ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
return Status::OK();
case NumberInt:
if ( !buffer->skip( sizeof(int32_t) ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
return Status::OK();
case Bool:
if ( !buffer->skip( sizeof(int8_t) ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
return Status::OK();
case NumberDouble:
case NumberLong:
case Timestamp:
case Date:
if ( !buffer->skip( sizeof(int64_t) ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
return Status::OK();
case DBRef:
status = buffer->readUTF8String( NULL );
if ( !status.isOK() )
return status;
buffer->skip( sizeof(OID) );
return Status::OK();
case RegEx:
status = buffer->readCString( NULL );
if ( !status.isOK() )
return status;
status = buffer->readCString( NULL );
if ( !status.isOK() )
return status;
return Status::OK();
case Code:
case Symbol:
case String:
status = buffer->readUTF8String( NULL );
if ( !status.isOK() )
return status;
return Status::OK();
case BinData: {
int sz;
if ( !buffer->readNumber<int>( &sz ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
if ( !buffer->skip( 1 + sz ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson" );
return Status::OK();
}
case CodeWScope:
*nextState = ValidationState::BeginCodeWScope;
return Status::OK();
case Object:
case Array:
*nextState = ValidationState::BeginObj;
return Status::OK();
default:
return Status( ErrorCodes::InvalidBSON, "invalid bson type" );
}
}
Status validateBSONIterative(Buffer* buffer) {
std::deque<ValidationObjectFrame> frames;
ValidationObjectFrame* curr = NULL;
ValidationState::State state = ValidationState::BeginObj;
while (state != ValidationState::Done) {
switch (state) {
case ValidationState::BeginObj:
frames.push_back(ValidationObjectFrame());
curr = &frames.back();
curr->setStartPosition(buffer->position());
curr->setIsCodeWithScope(false);
if (!buffer->readNumber<int>(&curr->expectedSize)) {
return Status(ErrorCodes::InvalidBSON,
"bson size is larger than buffer size");
}
state = ValidationState::WithinObj;
// fall through
case ValidationState::WithinObj: {
Status status = validateElementInfo(buffer, &state);
if (!status.isOK())
return status;
break;
}
case ValidationState::EndObj: {
int actualLength = buffer->position() - curr->startPosition();
if ( actualLength != curr->expectedSize ) {
return Status( ErrorCodes::InvalidBSON,
"bson length doesn't match what we found" );
}
frames.pop_back();
if (frames.empty()) {
state = ValidationState::Done;
}
else {
curr = &frames.back();
if (curr->isCodeWithScope())
state = ValidationState::EndCodeWScope;
else
state = ValidationState::WithinObj;
}
break;
}
case ValidationState::BeginCodeWScope: {
frames.push_back(ValidationObjectFrame());
curr = &frames.back();
curr->setStartPosition(buffer->position());
curr->setIsCodeWithScope(true);
if ( !buffer->readNumber<int>( &curr->expectedSize ) )
return Status( ErrorCodes::InvalidBSON, "invalid bson CodeWScope size" );
Status status = buffer->readUTF8String( NULL );
if ( !status.isOK() )
return status;
state = ValidationState::BeginObj;
break;
}
case ValidationState::EndCodeWScope: {
int actualLength = buffer->position() - curr->startPosition();
if ( actualLength != curr->expectedSize ) {
return Status( ErrorCodes::InvalidBSON,
"bson length for CodeWScope doesn't match what we found" );
}
frames.pop_back();
if (frames.empty())
return Status(ErrorCodes::InvalidBSON, "unnested CodeWScope");
curr = &frames.back();
state = ValidationState::WithinObj;
break;
}
case ValidationState::Done:
break;
}
}
return Status::OK();
}
} // namespace
Status validateBSON( const char* originalBuffer, uint64_t maxLength ) {
if ( maxLength < 5 ) {
return Status( ErrorCodes::InvalidBSON, "bson data has to be at least 5 bytes" );
}
Buffer buf( originalBuffer, maxLength );
return validateBSONIterative( &buf );
}
} // namespace mongo
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