Drop newline in tube.recvline by default

[peace-maker]

This is a breaking change!

Change the default value of the drop parameter to True to avoid the common recvline().strip() dance and be in line with other readline implementations:

Implementations stripping the final newline character when reading a line:

• C GNU readline
• C editline (readline alternative)
• C++ std::getline
• Rust BufRead::lines() (while BufRead::read_line() includes it (。﹏。))
• Go bufio.Reader.ReadLine

Python's IOBase.readline always includes the trailing newline, except for when there is none on the last line of a file.

My claim is that exploits usually don't care about the trailing newline requiring users to strip it before parsing the line for e.g. address leaks. All other tube.recvline* functions like recvlines or recvline_contains already have drop=True as the default and strip the newline character(s), so this increases the API's consistency.

This will break old exploits that expect the newline in some comparision, but the benefit for newer exploit not having to keep stripping seems to outweight this drawback.

if io.recvline() == b'expected\n': # expected value includes the \n and would break
  ...

line = io.recvline()
return line[:-1] # skip last character

Please leave a comment if there are concerns!

[k4lizen]

this change makes a lot of sense but the fact that it is breaking really really sucks because exploit.py's are shared through copy-paste rather than a version-locked git repo, so it's impossible to know for which pwntools version a given exploit is intended / will actually work. probably most users aren't going to be aware of this gotcha either :S