Python 3 Building an array of bytes

Question

I need to build a tcp frame with raw binary data  but all examples and tutorials I ve found talking about bytes always involve conversion from a string  and that s not what I need   In short  I need to build just an array of bytes   0xA2 0x01 0x02 0x03 0x04  Please note that I come from C C   world   I ve tried this   frame   b   frame    bytes  int  0xA2  16    frame    bytes  int  0x01  16    frame    bytes  int  0x02  16    frame    bytes  int  0x03  16    frame    bytes  int  0x04  16      Then  throw this frame variable to send method of socket  but not working as expected as frame doesn t contain what I want     I know this is a very basic question about Python  so if you could point me in the right direction

User · Answer

agf s bytearray solution is workable  but if you find yourself needing to build up more complicated packets using datatypes other than bytes  you can try struct pack    http   docs python org release 3 1 3 library struct html

User · Answer

Use a bytearray    gt  gt  gt  frame   bytearray    gt  gt  gt  frame append 0xA2   gt  gt  gt  frame append 0x01   gt  gt  gt  frame append 0x02   gt  gt  gt  frame append 0x03   gt  gt  gt  frame append 0x04   gt  gt  gt  frame bytearray b  xa2 x01 x02 x03 x04     or  using your code but fixing the errors   frame   b   frame    b  xA2   frame    b  x01   frame    b  x02   frame    b  x03  frame    b  x04

User · Answer

I think Scapy is what are you looking for    http   www secdev org projects scapy   you can build and send frames  packets  with it

User · Answer

Here is a solution to getting an array  list  of bytes   I found that you needed to convert the Int to a byte first  before passing it to the bytes     bytes int  0xA2   16  to bytes 1   big      Then create a list from the bytes   list frame    So your code should look like   frame   b   frame    bytes int  0xA2   16  to bytes 1   big    frame    bytes int  0x01   16  to bytes 1   big    frame    bytes int  0x02   16  to bytes 1   big    frame    bytes int  0x03   16  to bytes 1   big    frame    bytes int  0x04   16  to bytes 1   big    bytesList   list frame    The question was for an array  list  of bytes  You accepted an answer that doesn t tell how to get a list so I m not sure if this is actually what you needed

User · Answer

what about simply constructing your frame from a standard list    frame   bytes  0xA2 0x01 0x02 0x03 0x04     the bytes   constructor can build a byte frame from an iterable containing int values  an iterable is anything which implements the iterator protocol  an list  an iterator  an iterable object like what is returned by range

User · Answer

frame   b  xa2 x01 x02 x03 x04    wasn t mentionned till now

[python] Python 3 Building an array of bytes

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