1 files changed, 68 insertions, 0 deletions
diff --git a/host/crap.py b/host/crap.py
new file mode 100644
index 0000000..db9f7ee
--- /dev/null
+++ b/host/crap.py
@@ -0,0 +1,68 @@
+
+import socket
+import struct
+import zlib
+import io
+from time import time
+
+import config
+
+class CRAPClient:
+	def __init__(self, ip='127.0.0.1', port=1337):
+		self.ip, self.port = ip, port
+		self.sock = socket.Socket(socket.AF_INET, socket.SOCK_DGRAM)
+		self.close = self.sock.close
+
+	def sendframe(self, frame):
+		self.sock.sendto(frame, (self.ip, self.port))
+
+
+def _timestamped_recv(sock):
+	while True:
+		try:
+			data, addr = sock.recvfrom(config.frame_size*3+4)
+		except io.BlockingIOError as e:
+			raise StopIteration()
+		else:
+			yield time(), data, addr
+
+
+class CRAPServer:
+	def __init__(self, ip='', port=1337, blocking=False, log=print):
+		self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+		self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+		self.sock.setblocking(blocking)
+		self.sock.bind((ip, port))
+
+		self.current_client = None
+		self.last_timestamp = 0
+		self.begin_timestamp = 0
+		self.log = log
+
+	def close(self):
+		self.sock.close()
+
+	def __iter__(self):
+		for timestamp, data, (addr, sport) in _timestamped_recv(self.sock):
+			if data is None:
+				yield None
+
+			if timestamp - self.last_timestamp > config.udp_timeout\
+					or timestamp - self.begin_timestamp > config.udp_switch_interval:
+				self.current_client = addr
+				self.begin_timestamp = timestamp
+				self.log('\x1B[91mAccepting UDP data from\x1B[0m', addr)
+
+			if addr == self.current_client:
+				if len(data) == config.frame_size*3+4:
+					(crc1,), crc2 = struct.unpack('!I', data[-4:]), zlib.crc32(data, 0),
+					data = data[:-4] # crop CRC
+					if crc1 and crc1 != crc2: # crc1 zero-check for backward-compatibility
+						self.log('Error receiving UDP frame: Invalid frame CRC checksum: Expected {}, got {}'.format(crc2, crc1))
+						continue
+				elif len(data) != config.frame_size*3:
+					self.log('Error receiving UDP frame: Invalid frame size: {}'.format(len(data)))
+				self.last_timestamp = timestamp
+				yield data
+
+