def test_receiving_doesnt_block_if_there_is_already_decrypted_buffered_data(self):
# Here's what could (and would) happen before the relevant bug was fixed (assuming method
# M was trampolining unconditionally before actually reading):
# 1. One side sends n bytes, leaves connection open (important)
# 2. The other side uses method M to read m (where m < n) bytes, the underlying SSL
# implementation reads everything from the underlying socket, decrypts all n bytes,
# returns m of them and buffers n-m to be read later.
# 3. The other side tries to read the remainder of the data (n-m bytes), this blocks
# because M trampolines uncoditionally and trampoline will hang because reading from
# the underlying socket would block. It would block because there's no data to be read
# and the connection is still open; leaving the connection open /mentioned in 1./ is
# important because otherwise trampoline would return immediately and the test would pass
# even with the bug still present in the code).
#
# The solution is to first request data from the underlying SSL implementation and only
# trampoline if we actually need to read some data from the underlying socket.
#
# GreenSSLSocket.recv() wasn't broken but I've added code to test it as well for
# completeness.
content = b'xy'
def recv(sock, expected):
assert sock.recv(len(expected)) == expected
def recv_into(sock, expected):
buf = bytearray(len(expected))
assert sock.recv_into(buf, len(expected)) == len(expected)
assert buf == expected
for read_function in [recv, recv_into]:
print('Trying %s...' % (read_function,))
listener = listen_ssl_socket()
def accept(listener):
sock, addr = listener.accept()
sock.sendall(content)
return sock
accepter = eventlet.spawn(accept, listener)
client_to_server = None
try:
client_to_server = ssl.wrap_socket(eventlet.connect(listener.getsockname()))
for character in six.iterbytes(content):
character = six.int2byte(character)
print('We have %d already decrypted bytes pending, expecting: %s' % (
client_to_server.pending(), character))
read_function(client_to_server, character)
finally:
if client_to_server is not None:
client_to_server.close()
server_to_client = accepter.wait()
# Very important: we only want to close the socket *after* the other side has
# read the data it wanted already, otherwise this would defeat the purpose of the
# test (see the comment at the top of this test).
server_to_client.close()
listener.close()
def sender(f, content):
for ch in map(six.int2byte, six.iterbytes(content)):
eventlet.sleep(0.0001)
f.write(ch)
f.close()
def sender(f, content):
for ch in map(six.int2byte, six.iterbytes(content)):
eventlet.sleep(0.0001)
f.write(ch)
f.close()
