hostapd/wps-ap-nfc.py

#!/usr/bin/python
#
# Example nfcpy to hostapd wrapper for WPS NFC operations
# Copyright (c) 2012-2013, Jouni Malinen <j@w1.fi>
#
# This software may be distributed under the terms of the BSD license.
# See README for more details.

import os
import sys
import time
import argparse

import nfc
import nfc.ndef
import nfc.llcp
import nfc.handover

import logging

import wpaspy

wpas_ctrl = '/var/run/hostapd'
continue_loop = True
summary_file = None
success_file = None

def summary(txt):
    print(txt)
    if summary_file:
        with open(summary_file, 'a') as f:
            f.write(txt + "\n")

def success_report(txt):
    summary(txt)
    if success_file:
        with open(success_file, 'a') as f:
            f.write(txt + "\n")

def wpas_connect():
    ifaces = []
    if os.path.isdir(wpas_ctrl):
        try:
            ifaces = [os.path.join(wpas_ctrl, i) for i in os.listdir(wpas_ctrl)]
        except OSError as error:
            print("Could not find hostapd: ", error)
            return None

    if len(ifaces) < 1:
        print("No hostapd control interface found")
        return None

    for ctrl in ifaces:
        try:
            wpas = wpaspy.Ctrl(ctrl)
            return wpas
        except Exception as e:
            pass
    return None


def wpas_tag_read(message):
    wpas = wpas_connect()
    if (wpas == None):
        return False
    if "FAIL" in wpas.request("WPS_NFC_TAG_READ " + str(message).encode("hex")):
        return False
    return True


def wpas_get_config_token():
    wpas = wpas_connect()
    if (wpas == None):
        return None
    ret = wpas.request("WPS_NFC_CONFIG_TOKEN NDEF")
    if "FAIL" in ret:
        return None
    return ret.rstrip().decode("hex")


def wpas_get_password_token():
    wpas = wpas_connect()
    if (wpas == None):
        return None
    ret = wpas.request("WPS_NFC_TOKEN NDEF")
    if "FAIL" in ret:
        return None
    return ret.rstrip().decode("hex")


def wpas_get_handover_sel():
    wpas = wpas_connect()
    if (wpas == None):
        return None
    ret = wpas.request("NFC_GET_HANDOVER_SEL NDEF WPS-CR")
    if "FAIL" in ret:
        return None
    return ret.rstrip().decode("hex")


def wpas_report_handover(req, sel):
    wpas = wpas_connect()
    if (wpas == None):
        return None
    return wpas.request("NFC_REPORT_HANDOVER RESP WPS " +
                        str(req).encode("hex") + " " +
                        str(sel).encode("hex"))


class HandoverServer(nfc.handover.HandoverServer):
    def __init__(self, llc):
        super(HandoverServer, self).__init__(llc)
        self.ho_server_processing = False
        self.success = False

    # override to avoid parser error in request/response.pretty() in nfcpy
    # due to new WSC handover format
    def _process_request(self, request):
        summary("received handover request {}".format(request.type))
        response = nfc.ndef.Message("\xd1\x02\x01Hs\x12")
        if not request.type == 'urn:nfc:wkt:Hr':
            summary("not a handover request")
        else:
            try:
                request = nfc.ndef.HandoverRequestMessage(request)
            except nfc.ndef.DecodeError as e:
                summary("error decoding 'Hr' message: {}".format(e))
            else:
                response = self.process_request(request)
        summary("send handover response {}".format(response.type))
        return response

    def process_request(self, request):
        summary("HandoverServer - request received")
        try:
            print("Parsed handover request: " + request.pretty())
        except Exception as e:
            print(e)
        print(str(request).encode("hex"))

        sel = nfc.ndef.HandoverSelectMessage(version="1.2")

        for carrier in request.carriers:
            print("Remote carrier type: " + carrier.type)
            if carrier.type == "application/vnd.wfa.wsc":
                summary("WPS carrier type match - add WPS carrier record")
                data = wpas_get_handover_sel()
                if data is None:
                    summary("Could not get handover select carrier record from hostapd")
                    continue
                print("Handover select carrier record from hostapd:")
                print(data.encode("hex"))
                if "OK" in wpas_report_handover(carrier.record, data):
                    success_report("Handover reported successfully")
                else:
                    summary("Handover report rejected")

                message = nfc.ndef.Message(data);
                sel.add_carrier(message[0], "active", message[1:])

        print("Handover select:")
        try:
            print(sel.pretty())
        except Exception as e:
            print(e)
        print(str(sel).encode("hex"))

        summary("Sending handover select")
        self.success = True
        return sel


def wps_tag_read(tag):
    success = False
    if len(tag.ndef.message):
        for record in tag.ndef.message:
            print("record type " + record.type)
            if record.type == "application/vnd.wfa.wsc":
                summary("WPS tag - send to hostapd")
                success = wpas_tag_read(tag.ndef.message)
                break
    else:
        summary("Empty tag")

    if success:
        success_report("Tag read succeeded")

    return success


def rdwr_connected_write(tag):
    summary("Tag found - writing - " + str(tag))
    global write_data
    tag.ndef.message = str(write_data)
    success_report("Tag write succeeded")
    print("Done - remove tag")
    global only_one
    if only_one:
        global continue_loop
        continue_loop = False
    global write_wait_remove
    while write_wait_remove and tag.is_present:
        time.sleep(0.1)

def wps_write_config_tag(clf, wait_remove=True):
    summary("Write WPS config token")
    global write_data, write_wait_remove
    write_wait_remove = wait_remove
    write_data = wpas_get_config_token()
    if write_data == None:
        summary("Could not get WPS config token from hostapd")
        return

    print("Touch an NFC tag")
    clf.connect(rdwr={'on-connect': rdwr_connected_write})


def wps_write_password_tag(clf, wait_remove=True):
    summary("Write WPS password token")
    global write_data, write_wait_remove
    write_wait_remove = wait_remove
    write_data = wpas_get_password_token()
    if write_data == None:
        summary("Could not get WPS password token from hostapd")
        return

    print("Touch an NFC tag")
    clf.connect(rdwr={'on-connect': rdwr_connected_write})


def rdwr_connected(tag):
    global only_one, no_wait
    summary("Tag connected: " + str(tag))

    if tag.ndef:
        print("NDEF tag: " + tag.type)
        try:
            print(tag.ndef.message.pretty())
        except Exception as e:
            print(e)
        success = wps_tag_read(tag)
        if only_one and success:
            global continue_loop
            continue_loop = False
    else:
        summary("Not an NDEF tag - remove tag")
        return True

    return not no_wait


def llcp_startup(clf, llc):
    print("Start LLCP server")
    global srv
    srv = HandoverServer(llc)
    return llc

def llcp_connected(llc):
    print("P2P LLCP connected")
    global wait_connection
    wait_connection = False
    global srv
    srv.start()
    return True


def main():
    clf = nfc.ContactlessFrontend()

    parser = argparse.ArgumentParser(description='nfcpy to hostapd integration for WPS NFC operations')
    parser.add_argument('-d', const=logging.DEBUG, default=logging.INFO,
                        action='store_const', dest='loglevel',
                        help='verbose debug output')
    parser.add_argument('-q', const=logging.WARNING, action='store_const',
                        dest='loglevel', help='be quiet')
    parser.add_argument('--only-one', '-1', action='store_true',
                        help='run only one operation and exit')
    parser.add_argument('--no-wait', action='store_true',
                        help='do not wait for tag to be removed before exiting')
    parser.add_argument('--summary',
                        help='summary file for writing status updates')
    parser.add_argument('--success',
                        help='success file for writing success update')
    parser.add_argument('command', choices=['write-config',
                                            'write-password'],
                        nargs='?')
    args = parser.parse_args()

    global only_one
    only_one = args.only_one

    global no_wait
    no_wait = args.no_wait

    if args.summary:
        global summary_file
        summary_file = args.summary

    if args.success:
        global success_file
        success_file = args.success

    logging.basicConfig(level=args.loglevel)

    try:
        if not clf.open("usb"):
            print("Could not open connection with an NFC device")
            raise SystemExit

        if args.command == "write-config":
            wps_write_config_tag(clf, wait_remove=not args.no_wait)
            raise SystemExit

        if args.command == "write-password":
            wps_write_password_tag(clf, wait_remove=not args.no_wait)
            raise SystemExit

        global continue_loop
        while continue_loop:
            print("Waiting for a tag or peer to be touched")
            wait_connection = True
            try:
                if not clf.connect(rdwr={'on-connect': rdwr_connected},
                                   llcp={'on-startup': llcp_startup,
                                         'on-connect': llcp_connected}):
                    break
            except Exception as e:
                print("clf.connect failed")

            global srv
            if only_one and srv and srv.success:
                raise SystemExit

    except KeyboardInterrupt:
        raise SystemExit
    finally:
        clf.close()

    raise SystemExit

if __name__ == '__main__':
    main()