Refactor socket code.

[plomrogue2-experiments] / plom_socket_io.py

diff --git a/plom_socket_io.py b/plom_socket_io.py
deleted file mode 100644 (file)
index ebde3c1..0000000
--- a/plom_socket_io.py
+++ /dev/null
@@ -1,86 +0,0 @@
-class BrokenSocketConnection(Exception):
-    pass
-
-
-def send(socket, message):
-    """Send message via socket, encoded and delimited the way recv() expects.
-
-    In detail, all \ and $ in message are escaped with prefixed \, and an
-    unescaped $ is appended as a message delimiter. Then, socket.send() is
-    called as often as necessary to ensure message is sent fully, as
-    socket.send() due to buffering may not send all of it right away.
-
-    Assuming socket is blocking, it's rather improbable that socket.send() will
-    be partial / return a positive value less than the (byte) length of msg –
-    but not entirely out of the question. See:
-    - <http://stackoverflow.com/q/19697218>
-    - <http://stackoverflow.com/q/2618736>
-    - <http://stackoverflow.com/q/8900474>
-
-    This also handles a socket.send() return value of 0, which might be
-    possible or not (?) for blocking sockets:
-    - <http://stackoverflow.com/q/34919846>
-    """
-    escaped_message = ''
-    for char in message:
-        if char in ('\\', '$'):
-            escaped_message += '\\'
-        escaped_message += char
-    escaped_message += '$'
-    data = escaped_message.encode()
-    totalsent = 0
-    while totalsent < len(data):
-        socket_broken = False
-        try:
-            sent = socket.send(data[totalsent:])
-            socket_broken = sent == 0
-        except OSError as err:
-            if err.errno == 9:  # "Bad file descriptor", when connection broken
-                socket_broken = True
-            else:
-                raise err
-        if socket_broken:
-            raise BrokenSocketConnection
-        totalsent = totalsent + sent
-
-
-def recv(socket):
-    """Get full send()-prepared message from socket.
-
-    In detail, socket.recv() is looped over for sequences of bytes that can be
-    decoded as a Unicode string delimited by an unescaped $, with \ and $
-    escapable by \. If a sequence of characters that ends in an unescaped $
-    cannot be decoded as Unicode, None is returned as its representation. Stop
-    once socket.recv() returns nothing.
-
-    Under the hood, the TCP stack receives packets that construct the input
-    payload in an internal buffer; socket.recv(BUFSIZE) pops up to BUFSIZE
-    bytes from that buffer, without knowledge either about the input's
-    segmentation into packets, or whether the input is segmented in any other
-    meaningful way; that's why we do our own message segmentation with $ as a
-    delimiter.
-    """
-    esc = False
-    data = b''
-    msg = b''
-    while True:
-        data += socket.recv(1024)
-        if 0 == len(data):
-            return
-        cut_off = 0
-        for c in data:
-            cut_off += 1
-            if esc:
-                msg += bytes([c])
-                esc = False
-            elif chr(c) == '\\':
-                esc = True
-            elif chr(c) == '$':
-                try:
-                    yield msg.decode()
-                except UnicodeDecodeError:
-                    yield None
-                data = data[cut_off:]
-                msg = b''
-            else:
-                msg += bytes([c])