Method Details

• processPayload

  public static int processPayload(I2PAppContext ctx, NTCP2Payload.PayloadCallback cb, byte[] payload, int off, int length, boolean isHandshake) throws IOException, DataFormatException, I2NPMessageException

  Incoming payload. Calls the callback for each received block.

  Parameters:

  ctx - used to deserialize the RouterInfo and I2NP blocks

  cb - receives each block in the order it appears in the frame

  payload - the frame bytes, holding a sequence of blocks

  off - index in payload of the first block's type byte

  length - how many bytes of payload to parse, bounding the block walk

  isHandshake - true only for message 3 part 2, which allows only RouterInfo, options and padding

  Returns:

  number of blocks processed

  Throws:

  IOException - on major errors

  DataFormatException - on parsing of individual blocks

  I2NPMessageException - on parsing of I2NP block

• checkBlockOrder

  private static void checkBlockOrder(boolean isHandshake, int blocks, boolean gotPadding, boolean gotTermination, int type) throws IOException

  Check the payload-wide ordering rules for the next block: no block may follow padding, only padding may follow termination, and the first block of a handshake frame must be a RouterInfo.

  Parameters:

  isHandshake - true for the handshake frame, where the block is not allowed

  blocks - blocks already processed in this frame

  gotPadding - whether padding was already seen

  gotTermination - whether termination was already seen

  type - the next block type

  Throws:

  IOException - if ordering is violated

• checkFrameOverflow

  private static void checkFrameOverflow(int off, int length, int end, int i, int len, int blocks, int type) throws IOException

  Check that the block fits inside the frame. Called with i pointing just past the 3-byte header, so the block's offset is i - 3 - off. The frame contents are deliberately not included, they may be decrypted data; callers that want a dump log it at DEBUG.

  Parameters:

  off - index in payload of the first block's type byte, for the error message

  length - frame size in bytes, for the error message

  end - exclusive end index of the frame, i.e. off + length

  i - index of the block's first data byte, just past its 3-byte header

  len - the block's data length, as read from its header

  blocks - blocks already processed in this frame, for the error message

  type - the current block's type, for the error message

  Throws:

  IOException - if the block runs over the end of the frame

• checkHandshakeOnly

  private static void checkHandshakeOnly(boolean isHandshake, int type) throws IOException

  Check that the block type is not allowed in a handshake frame.

  Parameters:

  isHandshake - true for the handshake frame, where the block is not allowed

  type - the block's type, for the error message

  Throws:

  IOException - if the block appears in a handshake frame

• processDateTime

  private static void processDateTime(NTCP2Payload.PayloadCallback cb, byte[] payload, int i, int len) throws IOException, DataFormatException

  Parse a DATETIME block (exactly 4 bytes) and report it to the callback.

  Parameters:

  cb - receives the peer's clock, in milliseconds

  payload - the frame bytes

  i - index of the block's first data byte

  len - the block's data length, must be exactly 4

  Throws:

  IOException - if the length is not 4

  DataFormatException - if the callback cannot process the block

• processOptions

  private static void processOptions(NTCP2Payload.PayloadCallback cb, byte[] payload, int i, int len, boolean isHandshake) throws DataFormatException

  Copy an OPTIONS block and report it to the callback.

  Parameters:

  cb - receives a copy of the block's data

  payload - the frame bytes

  i - index of the block's first data byte

  len - the block's data length

  isHandshake - true for the handshake frame, passed on to the callback

  Throws:

  DataFormatException - if the callback cannot process the block

• processRouterInfo

  private static void processRouterInfo(I2PAppContext ctx, NTCP2Payload.PayloadCallback cb, byte[] payload, int i, int len, boolean isHandshake) throws IOException, DataFormatException

  Deserialize a ROUTERINFO block (a 1-byte flag then the RouterInfo) and report it to the callback.

  Parameters:

  ctx - used to deserialize the RouterInfo

  cb - receives the RouterInfo and whether the peer is a floodfill

  payload - the frame bytes

  i - index of the block's first data byte, the 1-byte flag

  len - the block's data length, including the flag byte

  isHandshake - true for the handshake frame, passed on to the callback

  Throws:

  IOException - if the RouterInfo cannot be read

  DataFormatException - if the RouterInfo is too big, or the callback rejects it

• processI2NP

  private static void processI2NP(I2PAppContext ctx, NTCP2Payload.PayloadCallback cb, byte[] payload, int i, int len) throws IOException, I2NPMessageException

  Parse an I2NP block (at least 9 bytes) and report it to the callback.

  Parameters:

  ctx - used to deserialize the message

  cb - receives the message

  payload - the frame bytes

  i - index of the block's first data byte

  len - the block's data length, at least 9

  Throws:

  IOException - if the block is shorter than 9 bytes

  I2NPMessageException - if the message cannot be deserialized, or the callback cannot process it

• processTermination

  private static boolean processTermination(NTCP2Payload.PayloadCallback cb, byte[] payload, int i, int len) throws IOException

  Parse a TERMINATION block (at least 9 bytes) and report it to the callback.

  Parameters:

  cb - receives the reason and the peer's last received date and time

  payload - the frame bytes

  i - index of the block's first data byte

  len - the block's data length, at least 9

  Returns:

  true, so the caller records that termination has been seen

  Throws:

  IOException - if the block is shorter than 9 bytes

• writePayload

  public static int writePayload(byte[] payload, int off, List<NTCP2Payload.Block> blocks)

  Write the blocks out to the frame, in list order.

  Parameters:

  payload - writes to it starting at off

  off - index in payload to write the first block's header at

  blocks - each one written at the offset the previous one ended at

  Returns:

  the new offset