ifsrv

#!/usr/bin/python
# -*- coding: utf-8 -*-
#
#  ifsrv.py - Interface service - network interface management daemon
#  
#  Copyright 2012  <xaxaxa@xaxaxa-mac>
#  
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#  
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#  
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#  MA 02110-1301, USA.
#  
#***config file format***
#*global options*
#	option (option name) (value)
#*config definition*
#	config (name):
#		option (name) (value)
#	...
#	end
#*interface definition*
#	iface (name):
#		option (name) (value)
#	...
#	end
#	
#***global options***
#	nowait: do not wait for the interface to be configured; (0|1)
#
#***config options***
#	these are self explanatory: type(static|dhcp), address, netmask, gateway
#
#***interface options***
#	nowait
#	config: configurations for this interface; separated by space; they're tried in the order specified

import sys,os,select,threading,subprocess,time;



class WaitableEvent:
    """Provides an abstract object that can be used to resume select loops with
    indefinite waits from another thread or process. This mimics the standard
    threading.Event interface."""
    def __init__(self):
        self._read_fd, self._write_fd = os.pipe()

    def wait(self, timeout=None):
        rfds, wfds, efds = select.select([self._read_fd], [], [], timeout)
        return self._read_fd in rfds

    def isSet(self):
        return self.wait(0)

    def clear(self):
        if self.isSet():
            os.read(self._read_fd, 1)

    def set(self):
        if not self.isSet():
            os.write(self._write_fd, b'1')

    def fileno(self):
        """Return the FD number of the read side of the pipe, allows this object to
        be used with select.select()."""
        return self._read_fd

    def __del__(self):
        os.close(self._read_fd)
        os.close(self._write_fd)




if sys.version_info < (3,):
    range = xrange;
#list of options that are arrays; true indicates one line should be split;
array_opts={"configs": True, "address": True, "up": False, "unplug": False, "postconfig": False, "preconfig": False};
def parseoption(tmp,target):
	optval=None;
	i=tmp.find(" ");
	if i<0: return;
	a=(tmp[:i],tmp[i+1:]);
	if a[0] in array_opts:
		if array_opts[a[0]]: optval=a[1].split();
		else: optval=[a[1]];
		if a[0] in target:
			target[a[0]].extend(optval);
			return;
	else: optval=a[1];
	target[a[0]]=optval;

def readconfig(f):
	obj={"options":{},"configs":{},"interfaces":{}};
	
	cur_scope=(None,None);
	while True:
		tmp=f.readline();
		if tmp==None or len(tmp)<=0: return obj;
		a=tmp.split(); tmp=tmp.strip();
		if len(a)<1: continue;
		cmd=a[0];
		#print(cmd[0]);
		if cmd[0]=='#': continue;
		if cmd=="option":
			if cur_scope[0]==None:
				parseoption(a[1:],obj["options"]);
			else: parseoption(a[1:],cur_scope[1]["options"]);
			continue;
		#if cur_scope[0]==None: #global scope
		if cmd=="iface": #add interface
			iface={"name":a[1],"options":{}};
			obj["interfaces"][a[1]]=iface;
			cur_scope=("interface", iface);
			continue;
		elif cmd=="config": #add config
			conf={"name":a[1],"options":{},"type":a[2]};
			obj["configs"][a[1]]=conf;
			cur_scope=("config", conf);
			continue;
		elif cmd=="end":
			cur_scope=(None,None);
			continue;
		#command not recognized. treating it as an option
		if cur_scope[0]==None:
			parseoption(tmp,obj["options"]);
		else: parseoption(tmp,cur_scope[1]["options"]);
	return obj;

conf=None;

def kill_dhclient(iface):
	try:
		f=open("/var/run/dhclient-"+iface["name"]+".pid","r");
		pid=int(f.readline().strip());
		os.kill(pid,9);
		#os.remove("/var/run/dhclient-"+iface["name"]+".pid");
	except: pass;
	try: os.remove("/var/run/dhclient-"+iface["name"]+".pid");
	except: pass;
def init_iface(iface):
	if "curconf" in iface: del iface["curconf"];
	#if "configured" in iface: del iface["configured"];
	kill_iface(iface);
	os.spawnvp(os.P_WAIT,"ifconfig",("ifconfig",iface["name"],"up"));
	os.spawnvp(os.P_WAIT,"ip",("ip","addr","flush","dev",iface["name"]));
	os.spawnvp(os.P_WAIT,"ip",("ip","route","flush","dev",iface["name"]));
	#os.spawnvp(os.P_WAIT,"dhclient",("dhclient","-x",iface["name"]));
	kill_dhclient(iface);
	#os.system("ifconfig "+iface["name"]);
def get_gateway(iface):
	s=subprocess.check_output(("ip","route","show","dev",iface["name"]));
	s=s.decode("utf-8");
	#print(s);
	s=s.split("\n");
	for l in s:
		#print(l);
		tmp=l.split();
		if len(tmp)>2:
			if tmp[0]=="default" and tmp[1]=="via": return tmp[2];
	return None;

def testconfig(iface,config=None):
	if config==None: config=iface["curconf"];
	if config==None: return False;
	if "pingtest" in config["options"] and config["options"]["pingtest"]=="1":
		t_o=2;
		h=None;
		if config["type"]=="static": h=config["options"]["gateway"];
		elif config["type"]=="dhcp": h=get_gateway(iface);
		if "pingtimeout" in config["options"]: t_o=int(config["options"]["pingtimeout"]);
		if "pinghost" in config["options"]: h=config["options"]["pinghost"];
		if h==None: print("warning: no gateway found, pinghost is not specified, and pingtest is enabled");
		else: print("pinging "+h);
		if h==None: return False;
		pid=os.spawnvp(os.P_NOWAIT,"ping",("ping","-c","1","-w",str(t_o),h));
		iface["pid"]=pid;
		(pid,retv)=os.waitpid(pid,0);
		try: del iface["pid"];
		except: pass;
		if retv!=0: return False;
		#return retv==0;
	#print("interface "+iface["name"]+" activated using config \""+config["name"]+"\"");
	return True;

def apply_config(iface,config,is_thread=False): #apply config
	init_iface(iface);
	if config["type"]=="static":
		print("setting ip addresses");
		for addr in config["options"]["address"]:
			pid=os.spawnvp(os.P_NOWAIT,"ip",("ip","addr","add","dev",iface["name"],"local",addr));
			iface["pid"]=pid;
			os.waitpid(pid,0);
			try: del iface["pid"];
			except: pass;
		if "gateway" in config["options"]:
			pid=os.spawnvp(os.P_NOWAIT,"ip",("ip","route","add","default","via",config["options"]["gateway"],"dev",iface["name"]));
			iface["pid"]=pid;
			os.waitpid(pid,0);
			try: del iface["pid"];
			except: pass;
	elif config["type"]=="dhcp":
		print("executing dhclient");
		pid=os.spawnvp(os.P_NOWAIT,"dhclient",("dhclient","-pf","/var/run/dhclient-"+iface["name"]+".pid",iface["name"]));
		iface["pid"]=pid;
		os.waitpid(pid,0);
		try: del iface["pid"];
		except: pass;
	if is_thread:
		if testconfig(iface,config):
			iface["curconf"]=config;
			postup(iface);
			return;
		do_activate_iface(iface,True);

def do_activate_iface(iface,is_thread=False):
	global conf;
	configs=iface["options"]["configs"];
	st=0;
	if "st" in iface: st=iface["st"];
	if st>=len(configs): st=0;
	c=None;
	for i in range(st,len(configs)):
		c=conf["configs"][configs[i]];
		if "nowait" in c["options"] and c["options"]["nowait"] and (not is_thread):
			iface["st"]=i+1;
			t=threading.Thread(target=apply_config,args=(iface,c,True));
			#iface["thr"]=t;
			t.start();
			return;
		apply_config(iface,c);
		if testconfig(iface,c):
			iface["curconf"]=c;
			postup(iface);
			return;
	iface["curconf"]=c;

def activate_iface(iface,nowait=None):
	if nowait==None: nowait=("nowait" in iface["options"] and iface["options"]["nowait"]=="1");
	if nowait:
		t=threading.Thread(target=do_activate_iface,args=(iface,True));
		#iface["thr"]=t;
		t.start();
	else: do_activate_iface(iface);
	
def detect_cable(iface):
	try:
		f=open("/sys/class/net/"+iface["name"]+"/carrier","r");
		s=f.readline().strip();
		f.close();
		return s!="0";
	except: return True;
def loadconfig():
	global conf;
	if conf!=None: return;
	f=open(sys.argv[1],'r');
	conf=readconfig(f);
	f.close();
	if len(conf["interfaces"])<=0:
		raise Error("at least one interface should be defined");
def kill_iface(iface):
	try:
		if "pid" in iface:
			os.kill(iface["pid"],9);
	except: pass

def execscr(s,iface):
	global conf;
	config=iface["curconf"];
	for c in s:
		print(c);
		eval(c);
def postup(iface):
	global conf;
	config=iface["curconf"];
	print("interface "+iface["name"]+" activated using config \""+config["name"]+"\"");
	try:
		if "up" in config["options"]: execscr(config["options"]["up"],iface);
	except BaseException as (a): print a;
	try:
		if "up" in iface["options"]: execscr(iface["options"]["up"],iface);
	except BaseException as (a): print a;
def run(evt=None):
	global conf;
	loadconfig();
	for iface in conf["interfaces"]:
		iface=conf["interfaces"][iface];
		init_iface(iface);
		iface["cable"]=detect_cable(iface);
		if iface["cable"]: activate_iface(iface);
		else: print(iface["name"]+" cable unplugged");
	if evt!=None: evt.set();
	while True:
		time.sleep(5);	#FIXME
		for iface in conf["interfaces"]:
			iface=conf["interfaces"][iface];
			try:
				tmp=detect_cable(iface);
				if tmp and (not iface["cable"]): #cable was plugged in
					#kill_iface(iface);
					print(iface["name"]+" cable plugged");
					activate_iface(iface,True);
				elif iface["cable"] and (not tmp):
					print(iface["name"]+" cable unplugged");
					if "unplug" in iface["name"]["options"]: execscr(iface["name"]["options"]["unplug"],iface);
					init_iface(iface);
				iface["cable"]=tmp;
			except: pass;
def do_start():
	global conf;
	loadconfig();
	t_o=None;
	if "timeout" in conf["options"]: t_o=float(conf["options"]["timeout"]);
	evt=WaitableEvent();
	tmp=os.fork();
	if tmp==0: #child
		run(evt);
	elif tmp>0: #parent
		if (not evt.wait(t_o)) and t_o>0: print("timed out waiting for interface config");
		return tmp;
		#print("dgsjdgghjasd");
	return 0;
def stop():
	global conf;
	loadconfig();
	try:
		pidfile="/var/run/ifsrv-"+conf["interfaces"].keys()[0]+".pid";
		try:
			f=open(pidfile,"r");
			pid=int(f.readline().strip());
			os.kill(pid,9);
			f.close();
		except: pass;
		os.remove(pidfile);
	except: pass;
def start():
	global conf;
	loadconfig();
	stop();
	pid=do_start();
	if pid>0:
		pidfile="/var/run/ifsrv-"+conf["interfaces"].keys()[0]+".pid";
		f=open(pidfile,"w+",0666);
		f.write(str(pid)+"\n");
		f.close();
def showconf():
	global conf;
	loadconfig();
	print conf;
def restart():
	start();
def main():
	if len(sys.argv)<2:
		print("to use ifsrv, put '#!/path/to/ifsrv' at the top of your config file and put the config file in /etc/init.d/ or whatever; don't forget to chmod it");
		return 0;
	if len(sys.argv)<3:
		print("usage: %s (start|stop|restart)"%sys.argv[1]);
		return 0;
	eval(sys.argv[2]+"()");
	return 0;

if __name__ == '__main__':
	main();