socketfromfd -- Create a socket from a file descriptor
socketfromfd is an enhanced version of socket.fromfd() from Python's standard library. It uses ctypes and libc's getsockopt() function to auto-detect the file descriptor's socket family, type and protocol.
>>> import socket
>>> sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>>> sock
<socket.socket fd=4, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('0.0.0.0', 0)>
>>> from socketfromfd import fromfd
>>> newsock = fromfd(sock.fileno())
>>> newsock
<socket.socket fd=5, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=6, laddr=('0.0.0.0', 0)>The parameter ``keep_fdlets you re-use the original fd under Python 3. Because Python 2 always duplicated the fd, it is not possible to provide the same behavior with Python 2. Insteadkeep_fd=False``` simply closes
the input fd.
>>> newsock = fromfd(sock.fileno(), keep_fd=False)
>>> newsock
<socket.socket fd=4, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=6, laddr=('0.0.0.0', 0)>What's wrong with the Python standard library?
Python assumes AF_INET (aka IPv4) as default. It breaks even this
simple example in multiple ways. For one getpeername returns something
that is neither a valid IPv4 nor a valid IPv6 address. For ``AF_INETthe methodgetpeername``` is suppose to return a tuple of two elements,
not four elements, too.
>>> import socket
>>> sock = socket.create_connection(('www.python.org', 443))
>>> sock.family
<AddressFamily.AF_INET6: 10>
>>> sock.getpeername()
('2a04:4e42:1b::223', 443, 0, 0)
>>> newsock = socket.socket(fileno=sock.fileno())
>>> newsock.family
<AddressFamily.AF_INET: 2>
>>> newsock.getpeername()
('2a04:4e42:1b:0:4890:7147:307f:0%1197553104', 443, 0, 1197553104)
>>> socket.gethostbyname('www.python.org')
'151.101.112.223'
>>> sock4 = socket.create_connection(('151.101.112.223', 443))
>>> sock4.getpeername()
('151.101.112.223', 443)
