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Peers can start discovery at ~ the same time

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Still needs some improvement, hard to test because socket has to be bound.
This commit is contained in:
Philip Trauner 2016-10-09 00:52:34 +02:00
parent 1ee7b787ed
commit 55f9dd4425
1 changed files with 41 additions and 40 deletions
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81
Shared/Disc0very.py
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@ -1,13 +1,15 @@
from socket import *
from random import getrandbits
from random import choice
from time import time
from time import sleep
import Utils
import Logging
from _thread import start_new_thread
HEY = "HEY".encode()
IDENT_SEED_LENGTH = 64
NAY = "NAY".encode()
WHAT = "WHAT".encode()
@ -17,80 +19,79 @@ class MissingInterfaceError(TypeError):
class Disc0very:
def __init__(self, port, interface="eth0", max_peers=32):
def __init__(self, port, interface=None, max_peers=32):
self.port = port
self.ident = getrandbits(max_peers * 2)
self.sock = socket(AF_INET, SOCK_DGRAM)
self.sock.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
self.sock.setsockopt(SOL_SOCKET, SO_BROADCAST, 1)
self.sock.bind(("", self.port))
self.ip_address = Utils.get_ip_address(interface)
self.discovering = False
self.enlisting = False
def discover(self, time_out=2):
if not self.enlisting:
self.discovering = True
self.sock.setblocking(False)
self.sock.sendto(HEY, ('255.255.255.255', self.port))
end_time = time() + time_out
servers = []
while time() < end_time:
try:
data = self.sock.recv(512)
if data != HEY:
servers.append(data)
except BlockingIOError:
sleep(0.2)
self.discovering = False
if len(servers) == 0:
return None
elif len(servers) > 1:
self.sock.sendto(WHAT, ('255.255.255.255', self.port))
else:
return servers[0]
# Not thread-safe if ran in parallel with __enlist
def discover(self, time_out=1):
self.sock.setblocking(False)
end_time = time() + time_out
servers = []
self.sock.sendto(HEY, ('255.255.255.255', self.port))
while time() < end_time:
try:
data, address = self.sock.recvfrom(512)
address = address[0]
# If enlisted peer responds with ip address
if data not in (HEY, NAY) and address != self.ip_address and not data in servers:
servers.append(data)
# If another peer is currently discovering
elif data == HEY and address != self.ip_address:
self.sock.sendto(NAY, ('255.255.255.255', self.port))
return self.discover(time_out=time_out)
# If another peer gave up
elif data == NAY and address != self.ip_address:
return None
except BlockingIOError:
sleep((choice(range(1, 10)) / 2) / 10)
if len(servers) == 0:
return None
elif len(servers) > 1:
self.sock.sendto(WHAT, ('255.255.255.255', self.port))
else:
return servers[0]
def enlist(self, interface, blocking=False):
if not self.discovering:
if blocking:
self.__enlist(interface)
else:
start_new_thread(self.__enlist, (interface, ))
if blocking:
self.__enlist(interface)
else:
start_new_thread(self.__enlist, (interface, ))
# Not thread-safe if ran in parallel with discover
# Interface should always be provided when using a Wallaby
# because wlan0 and wlan1 have an IP address assigned
def __enlist(self, interface=None):
self.enlisting = True
self.sock.setblocking(True)
ip_address = Utils.get_ip_address(interface)
data = ""
while True:
try:
data = self.sock.recv(512)
data, address = self.sock.recvfrom(512)
except BlockingIOError:
sleep(0.1)
if data == HEY:
self.sock.sendto(ip_address.encode(), ('255.255.255.255', self.port))
self.sock.sendto(self.ip_address.encode(), ('255.255.255.255', self.port))
elif data == WHAT:
Logging.error("Apparently more than one server is running. "
"Investigating...")
# Discover and if other server is found shutdown
def start():
print("starting")
if __name__ == "__main__":
from time import sleep
disc0very = Disc0very(3077)
server = disc0very.discover()
if not server:
print("enlisted")
print("enlisting")
disc0very.enlist(None, blocking=True)
else:
print(server)