/// <summary> /// Continue scanning input starting from offset_ to find the element end. /// If the end of the element which started at offset 0 is found, this returns /// true and getOffset() is the length of the element. Otherwise, this returns /// false which means you should read more into input and call again. /// </summary> /// /// <param name="input">You have to pass in input each time because the buffer could be reallocated.</param> /// <returns>true if found the element end, false if not.</returns> public bool findElementEnd(ByteBuffer input) { if (gotElementEnd_) { // Someone is calling when we already got the end. return(true); } TlvDecoder decoder = new TlvDecoder(input); while (true) { if (offset_ >= input.limit()) { // All the cases assume we have some input. Return and wait for more. return(false); } if (state_ == TlvStructureDecoder.READ_TYPE) { int firstOctet = (int)input.get(offset_) & 0xff; offset_ += 1; if (firstOctet < 253) { // The value is simple, so we can skip straight to reading the length. state_ = TlvStructureDecoder.READ_LENGTH; } else { // Set up to skip the type bytes. if (firstOctet == 253) { nBytesToRead_ = 2; } else if (firstOctet == 254) { nBytesToRead_ = 4; } else { // value == 255. nBytesToRead_ = 8; } state_ = TlvStructureDecoder.READ_TYPE_BYTES; } } else if (state_ == TlvStructureDecoder.READ_TYPE_BYTES) { int nRemainingBytes = input.limit() - offset_; if (nRemainingBytes < nBytesToRead_) { // Need more. offset_ += nRemainingBytes; nBytesToRead_ -= nRemainingBytes; return(false); } // Got the type bytes. Move on to read the length. offset_ += nBytesToRead_; state_ = TlvStructureDecoder.READ_LENGTH; } else if (state_ == TlvStructureDecoder.READ_LENGTH) { int firstOctet_0 = (int)input.get(offset_) & 0xff; offset_ += 1; if (firstOctet_0 < 253) { // The value is simple, so we can skip straight to reading // the value bytes. nBytesToRead_ = firstOctet_0; if (nBytesToRead_ == 0) { // No value bytes to read. We're finished. gotElementEnd_ = true; return(true); } state_ = TlvStructureDecoder.READ_VALUE_BYTES; } else { // We need to read the bytes in the extended encoding of // the length. if (firstOctet_0 == 253) { nBytesToRead_ = 2; } else if (firstOctet_0 == 254) { nBytesToRead_ = 4; } else { // value == 255. nBytesToRead_ = 8; } // We need to use firstOctet in the next state. firstOctet_ = firstOctet_0; state_ = TlvStructureDecoder.READ_LENGTH_BYTES; } } else if (state_ == TlvStructureDecoder.READ_LENGTH_BYTES) { int nRemainingBytes_1 = input.limit() - offset_; if (!useHeaderBuffer_ && nRemainingBytes_1 >= nBytesToRead_) { // We don't have to use the headerBuffer. Set nBytesToRead. decoder.seek(offset_); nBytesToRead_ = decoder.readExtendedVarNumber(firstOctet_); // Update offset_ to the decoder's offset after reading. offset_ = decoder.getOffset(); } else { useHeaderBuffer_ = true; int nNeededBytes = nBytesToRead_ - headerBuffer_.position(); if (nNeededBytes > nRemainingBytes_1) { // We can't get all of the header bytes from this input. // Save in headerBuffer. if (headerBuffer_.position() + nRemainingBytes_1 > headerBuffer_ .limit()) { // We don't expect this to happen. throw new Exception( "Cannot store more header bytes than the size of headerBuffer"); } ByteBuffer remainingInput = input.duplicate(); remainingInput.position(offset_); headerBuffer_.put(remainingInput); offset_ += nRemainingBytes_1; return(false); } // Copy the remaining bytes into headerBuffer, read the // length and set nBytesToRead. if (headerBuffer_.position() + nNeededBytes > headerBuffer_ .limit()) { // We don't expect this to happen. throw new Exception( "Cannot store more header bytes than the size of headerBuffer"); } ByteBuffer remainingLengthBytes = input.duplicate(); remainingLengthBytes.position(offset_); remainingLengthBytes.limit(offset_ + nNeededBytes); headerBuffer_.put(remainingLengthBytes); offset_ += nNeededBytes; // Use a local decoder just for the headerBuffer. headerBuffer_.flip(); TlvDecoder bufferDecoder = new TlvDecoder(headerBuffer_); // Replace nBytesToRead with the length of the value. nBytesToRead_ = bufferDecoder .readExtendedVarNumber(firstOctet_); } if (nBytesToRead_ == 0) { // No value bytes to read. We're finished. gotElementEnd_ = true; return(true); } // Get ready to read the value bytes. state_ = TlvStructureDecoder.READ_VALUE_BYTES; } else if (state_ == TlvStructureDecoder.READ_VALUE_BYTES) { int nRemainingBytes_2 = input.limit() - offset_; if (nRemainingBytes_2 < nBytesToRead_) { // Need more. offset_ += nRemainingBytes_2; nBytesToRead_ -= nRemainingBytes_2; return(false); } // Got the bytes. We're finished. offset_ += nBytesToRead_; gotElementEnd_ = true; return(true); } else { // We don't expect this to happen. throw new Exception("findElementEnd: unrecognized state"); } } }
/// <summary> /// Continue scanning input starting from offset_ to find the element end. /// If the end of the element which started at offset 0 is found, this returns /// true and getOffset() is the length of the element. Otherwise, this returns /// false which means you should read more into input and call again. /// </summary> /// /// <param name="input">You have to pass in input each time because the buffer could be reallocated.</param> /// <returns>true if found the element end, false if not.</returns> public bool findElementEnd(ByteBuffer input) { if (gotElementEnd_) // Someone is calling when we already got the end. return true; TlvDecoder decoder = new TlvDecoder(input); while (true) { if (offset_ >= input.limit()) // All the cases assume we have some input. Return and wait for more. return false; if (state_ == TlvStructureDecoder.READ_TYPE) { int firstOctet = (int) input.get(offset_) & 0xff; offset_ += 1; if (firstOctet < 253) // The value is simple, so we can skip straight to reading the length. state_ = TlvStructureDecoder.READ_LENGTH; else { // Set up to skip the type bytes. if (firstOctet == 253) nBytesToRead_ = 2; else if (firstOctet == 254) nBytesToRead_ = 4; else // value == 255. nBytesToRead_ = 8; state_ = TlvStructureDecoder.READ_TYPE_BYTES; } } else if (state_ == TlvStructureDecoder.READ_TYPE_BYTES) { int nRemainingBytes = input.limit() - offset_; if (nRemainingBytes < nBytesToRead_) { // Need more. offset_ += nRemainingBytes; nBytesToRead_ -= nRemainingBytes; return false; } // Got the type bytes. Move on to read the length. offset_ += nBytesToRead_; state_ = TlvStructureDecoder.READ_LENGTH; } else if (state_ == TlvStructureDecoder.READ_LENGTH) { int firstOctet_0 = (int) input.get(offset_) & 0xff; offset_ += 1; if (firstOctet_0 < 253) { // The value is simple, so we can skip straight to reading // the value bytes. nBytesToRead_ = firstOctet_0; if (nBytesToRead_ == 0) { // No value bytes to read. We're finished. gotElementEnd_ = true; return true; } state_ = TlvStructureDecoder.READ_VALUE_BYTES; } else { // We need to read the bytes in the extended encoding of // the length. if (firstOctet_0 == 253) nBytesToRead_ = 2; else if (firstOctet_0 == 254) nBytesToRead_ = 4; else // value == 255. nBytesToRead_ = 8; // We need to use firstOctet in the next state. firstOctet_ = firstOctet_0; state_ = TlvStructureDecoder.READ_LENGTH_BYTES; } } else if (state_ == TlvStructureDecoder.READ_LENGTH_BYTES) { int nRemainingBytes_1 = input.limit() - offset_; if (!useHeaderBuffer_ && nRemainingBytes_1 >= nBytesToRead_) { // We don't have to use the headerBuffer. Set nBytesToRead. decoder.seek(offset_); nBytesToRead_ = decoder.readExtendedVarNumber(firstOctet_); // Update offset_ to the decoder's offset after reading. offset_ = decoder.getOffset(); } else { useHeaderBuffer_ = true; int nNeededBytes = nBytesToRead_ - headerBuffer_.position(); if (nNeededBytes > nRemainingBytes_1) { // We can't get all of the header bytes from this input. // Save in headerBuffer. if (headerBuffer_.position() + nRemainingBytes_1 > headerBuffer_ .limit()) // We don't expect this to happen. throw new Exception( "Cannot store more header bytes than the size of headerBuffer"); ByteBuffer remainingInput = input.duplicate(); remainingInput.position(offset_); headerBuffer_.put(remainingInput); offset_ += nRemainingBytes_1; return false; } // Copy the remaining bytes into headerBuffer, read the // length and set nBytesToRead. if (headerBuffer_.position() + nNeededBytes > headerBuffer_ .limit()) // We don't expect this to happen. throw new Exception( "Cannot store more header bytes than the size of headerBuffer"); ByteBuffer remainingLengthBytes = input.duplicate(); remainingLengthBytes.position(offset_); remainingLengthBytes.limit(offset_ + nNeededBytes); headerBuffer_.put(remainingLengthBytes); offset_ += nNeededBytes; // Use a local decoder just for the headerBuffer. headerBuffer_.flip(); TlvDecoder bufferDecoder = new TlvDecoder(headerBuffer_); // Replace nBytesToRead with the length of the value. nBytesToRead_ = bufferDecoder .readExtendedVarNumber(firstOctet_); } if (nBytesToRead_ == 0) { // No value bytes to read. We're finished. gotElementEnd_ = true; return true; } // Get ready to read the value bytes. state_ = TlvStructureDecoder.READ_VALUE_BYTES; } else if (state_ == TlvStructureDecoder.READ_VALUE_BYTES) { int nRemainingBytes_2 = input.limit() - offset_; if (nRemainingBytes_2 < nBytesToRead_) { // Need more. offset_ += nRemainingBytes_2; nBytesToRead_ -= nRemainingBytes_2; return false; } // Got the bytes. We're finished. offset_ += nBytesToRead_; gotElementEnd_ = true; return true; } else // We don't expect this to happen. throw new Exception("findElementEnd: unrecognized state"); } }