from twisted.plugin import IPlugin
from txircd.module_interface import IModuleData, ModuleData
from zope.interface import implements

class ConnectionLimit(ModuleData):
    implements(IPlugin, IModuleData)

    name = "ConnectionLimit"
    peerConnections = {}

    def hookIRCd(self, ircd):
        self.ircd = ircd

    def actions(self):
        return [ ("userconnect", 100, self.handleLocalConnect),
                 ("remoteregister", 100, self.handleRemoteConnect),
                 ("quit", 100, self.handleDisconnect),
                 ("remotequit", 100, self.handleDisconnect) ]

    def handleLocalConnect(self, user, *params):
        ip = user.ip
        if self.addToConnections(ip) and self.peerConnections[ip] > self.ircd.config.getWithDefault("connlimit_globmax", 3):
            user.disconnect("No more connections allowed from your IP ({})".format(ip))
            return None
        return True

    def handleRemoteConnect(self, user, *params):
        self.addToConnections(user.ip)

    def handleDisconnect(self, user, *params):
        ip = user.ip
        if ip in self.peerConnections:
            self.peerConnections[ip] -= 1
            if self.peerConnections[ip] < 1:
                del self.peerConnections[ip]

    def addToConnections(self, ip):
        if ip in self.ircd.config.getWithDefault("connlimit_whitelist", []):
            return False
        if ip in self.peerConnections:
            self.peerConnections[ip] += 1
        else:
            self.peerConnections[ip] = 1
        return True

    def load(self):
        for user in self.ircd.users:
            self.addToConnections(user.ip)

connLimit = ConnectionLimit()
Implement the connection limit module
Implement the connection limit module
