#!/usr/bin/env python

import sys, logging
import tftpy
import re
import signal

LEASES_FILE = "/var/lib/dhcp/dhcpd.leases"

def get_mac(address):
    """Gets MAC address from dhcpd leases based on IP address."""
    f = open(LEASES_FILE,"r")
    in_lease = False
    for line in f:
        line = line.split("#")[0]
        parts = line.strip().split()
        if not parts:
            continue
        if not in_lease and parts[0] == "lease":
            in_lease = parts[1]
            continue
        field_name = parts[0]
        if field_name == "hardware" and in_lease == address:
            return parts[2][:-1]
        elif field_name == "}":
            in_lease = False
    return None

file_hooks = {}
def hook_dispatcher(path, remote):
    for pattern, hook in file_hooks.iteritems():
        match = re.match(pattern, path)
        if match:
            data = hook(path, match, remote)
            if data:
                return data
    return None

def hook(pattern, match_mac=None):
    def decorator(f):
        def wrapper(path, match, remote):
            if match_mac:
                mac = get_mac([0])
                if match_mac and mac != match_mac:
                    return None

            return f(path, match, remote)
        file_hooks[pattern] = wrapper
        return f
    return decorator

import hooks

def main():
    def sighup_handler(signum, frame):
        signal.siginterrupt(signal.SIGHUP, False)
        sys.stderr.write("Reloading config...\n")
        sys.stderr.flush()
        file_hooks = {}
        reload(hooks)

    signal.signal(signal.SIGHUP, sighup_handler)
    server = tftpy.TftpServer("/var/khepri/tftp-root/", dyn_file_func=hook_dispatcher)
    try:
        server.listen("10.8.1.1", 5000)
    except tftpy.TftpException, err:
        sys.stderr.write("%s\n" % str(err))
        sys.exit(1)
    except KeyboardInterrupt:
        pass