引き続き、PythonでIP Messengerのサービスにエントリして送られてくるメッセージを処理する辺りを。前回今回Raspberry Pi関係ないですね。

import socket
import random

USER_NAME = 'ipmsg_light'
MACHINE_NAME = 'raspberrypi'
BROADCAST = '255.255.255.255'

IPMSG_VERSION           = 1
IPMSG_DEFAULT_PORT      = 2425

IPMSG_BR_ENTRY          = 0x00000001L
IPMSG_BR_EXIT           = 0x00000002L
IPMSG_ANSENTRY          = 0x00000003L
IPMSG_BR_ABSENCE        = 0x00000004L
IPMSG_SENDMSG           = 0x00000020L
IPMSG_RECVMSG           = 0x00000021L

PORT = IPMSG_DEFAULT_PORT
# -----
def turn_the_light_on():
    print 'light on.'

def turn_the_light_off():
    print 'light off.'

def get_mode(command):
    return command & 0x000000FFL

def get_msg_header(cmd, msg):
    packet_num = random.randrange(1, 10000000)
    return "%s:%s:%s:%s:%s:%s" % (IPMSG_VERSION, packet_num, USER_NAME, MACHINE_NAME, cmd, msg)

def get_ans_cmd(cmd):
    if cmd == IPMSG_BR_ENTRY:
        return IPMSG_ANSENTRY
    elif cmd == IPMSG_SENDMSG:
        return IPMSG_RECVMSG

    return -1

def set_light_status_by_user_status(user_dic):
    if len(user_dic) == 0:
        turn_the_light_off()
    elif reduce(lambda x,y: x+y, user_dic.values()) == 0:
        turn_the_light_off()
    else:
        turn_the_light_on()

def set_light_status(user, msg_text, user_dic):
    if user not in user_dic:
        user_dic[user] = 0

    msg_cmd = msg_text.replace("\0", '').strip().lower()
    if msg_cmd == "on":
        user_dic[user] = 1
    elif msg_cmd == 'off':
        user_dic[user] = 0
    elif msg_cmd == 'kill':
        user_dic.clear()
    else:
        user_dic[user] = (0 if user_dic[user] == 1 else 1)

    set_light_status_by_user_status(user_dic)

def remove_user(user, user_dic):
    if user in user_dic:
        user_dic.pop(user)

    set_light_status_by_user_status(user_dic)

def parse_recv_msg(msg):
    msg_ary = msg.split(':')
    if len(msg_ary) < 5 :
        return

    return (msg_ary[1], msg_ary[2], msg_ary[3], msg_ary[4], msg_ary[5])

# -----
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
s.bind(('0.0.0.0', PORT))

msg = get_msg_header(IPMSG_BR_ENTRY, '')
s.sendto(msg, (BROADCAST, PORT))

user_dic = {}

while True:
    (recv_msg, client_addr) = s.recvfrom(1024)

    print recv_msg

    msg_tuple = parse_recv_msg(recv_msg)
    if msg_tuple is None:
        continue

    (packet_num, send_user, send_machine, recv_cmd, recv_msg_text) = msg_tuple

    cmd = get_mode(int(recv_cmd))

    if cmd == IPMSG_SENDMSG:
        set_light_status(send_user, recv_msg_text, user_dic)
    elif cmd == IPMSG_BR_EXIT:
        remove_user(send_user, user_dic)    

    ans_cmd = get_ans_cmd(cmd)

    if ans_cmd < 0 :
        continue

    ans_msg = ''
    if ans_cmd == IPMSG_ANSENTRY:
        ans_msg = get_msg_header(ans_cmd, USER_NAME)
    else :
        ans_msg = get_msg_header(ans_cmd, packet_num)

    s.sendto(ans_msg, client_addr)

s.close()

こんな感じで他のIP Messengerから送られてくるメッセージを処理できてる気がします。正直Python詳しくないので適当です。

基本的にメッセージ本文無しで回転灯をON/OFFさせるように考えていますが、本文にonかoffが書かれていればそれに従い、killとあれば他のユーザの状況にかかわらず常にOFFにするようにしてみました。

とりあえずメッセージを受けて回転灯の状態を操作できそうになったので、on/off文字をprintしている箇所を変更してRaspberry PiのGPIOを弄っていきます。