extctrl2014.py 13.5 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418
#!/usr/bin/python

import random
import struct
import StringIO
import time
import threading

#
# Packet format
#
#   +----+----+----+----+----+----+
#   | destination                    (6 bytes)
#   +----+----+----+----+----+----+
#   | source                         (6 bytes)
#   +----+----+
#   | eth_type                       (2 bytes 'EX')
#   +----+
#   | kind+flags                     (1 byte)
#   +....+
#   | channel                        (packed32)
#   +----+----+----+----+
#   | cookie                         (uint32, XOR of both first_indices)
#   +----+----+----+----+
#   | index                          (uint32)
#   +....+
#   | frag_num                       (packed32)
#   +....+
#   | frag_length                    (packed32)
#   +....+
#   | data
#   +
#

flag_MASK =           0x07
flag_LAST_FRAG =      0x01
flag_NEED_ACK =       0x02
flag_IS_ACK =         0x04
kind_MASK =           0x30
kind_INIT =           0x10
kind_DATA =           0x20

class UnexpectedFragment(Exception):

    pass

class Decoder(object):

    def __init__(self, data):
        self.buf = StringIO.StringIO(data)

    def read(self, count):
        return self.buf.read(count)
    
    def unpack(self, format):
        size = struct.calcsize(format)
        data = self.buf.read(size)
        result = struct.unpack(format, data)
        return result[0]

    def decode_uint32(self):
        return self.unpack("!I")

    def decode_byte(self):
        return self.unpack("!B")
    
    def decode_packed32(self):
        result = 0
        while True:
            tmp = self.decode_byte()
            result = (result << 7) | (tmp & 0x7f)
            if (tmp & 0x80) == 0:
                break
        return result

class Encoder(object):

    def __init__(self):
        self.buf = StringIO.StringIO()
   
    def __repr__(self):
        return "Codec([%s])" % (" ".join(
            map(lambda b: "0x%2.2x" % ord(b), self.getvalue())))

    def getvalue(self):
        return self.buf.getvalue()
    
    def write(self, data):
        self.buf.write(data)
        
    def pack(self, format, *args):
        self.buf.write(struct.pack(format, *args))

    def encode_uint32(self, value):
        self.pack("!I", value)

    def encode_byte(self, value):
        self.pack("!B", value)
    
    def encode_packed32(self, value):
        value = value & 0xffffffff
        tmp = [ value & 0x7f ]
        value = value >> 7
        while value:
            tmp.append(value & 0x7f | 0x80)
            value= value >> 7
            pass
        for c in reversed(tmp):
            self.encode_byte(c) 
            pass
        pass

class Fragmenter(Encoder):

    def __init__(self, destination, flags, channel, cookie, index):
        super(Fragmenter, self).__init__()
        self.destination = destination
        self.flags = flags
        self.cookie = cookie
        self.channel = channel
        self.index = index

    def fragments(self, max_length=1480):
        data = self.getvalue()
        fragment_number = 0
        while len(data) > 0 or fragment_number == 0:
            length = min(len(data), max(1, max_length))
            remaining = data[length:]
            data = data[0:length]
            fragment = Encoder()
            fragment.write(self.destination)
            fragment.write('\x00\x00\x00\x00\x00\x00')
            fragment.write('EX')
            if len(remaining) == 0:
                fragment.encode_byte(self.flags | flag_LAST_FRAG)
            else:
                fragment.encode_byte(self.flags)
            fragment.encode_packed32(self.channel)
            fragment.encode_uint32(self.cookie)
            fragment.encode_uint32(self.index)
            fragment.encode_packed32(fragment_number)
            fragment.encode_packed32(length)
            fragment.write(data)
            yield fragment
            data = remaining
            fragment_number += 1
            
    def __repr__(self):
        return "Fragmenter([%s])" % (" ".join(
            map(lambda b: "0x%2.2x" % ord(b), self.getvalue())))

class Packet:

    def __init__(self, data):
        buf = Decoder(data)
        self.destination = buf.read(6)
        self.source = buf.read(6)
        self.eth_type = buf.read(2)
        flags = buf.decode_byte()
        self.flags = flags & flag_MASK
        self.kind = flags & kind_MASK
        self.channel = buf.decode_packed32()
        self.cookie = buf.decode_uint32()
        self.index = buf.decode_uint32()
        self.frag_num = buf.decode_packed32()
        frag_length = buf.decode_packed32()
        self.data = buf.read(frag_length)

    def join(self, other):
        if self.destination != other.destination:
            return None
        if self.source != other.source:
            return None
        if self.kind != other.kind:
            return None
        if self.channel != other.channel:
            return None
        if self.cookie != other.cookie:
            return None
        if self.index != other.index:
            return None
        if self.frag_num + 1 != other.frag_num:
            return None
        self.flags = other.flags
        self.frag_num = other.frag_num
        self.data += other.data
        return self
        
    def __repr__(self):
        return "Packet(%s %s %d index=%x flags=%x kind=%x data='%s'" % (
            ":".join(map(lambda b: "%02.2x" % ord(b), self.destination)),
            ":".join(map(lambda b: "%02.2x" % ord(b), self.source)),
            self.channel,
            self.index,
            self.flags,
            self.kind,
            "".join(map(lambda b: "\\x%02.2x" % ord(b), self.data)),
       )

class ExtCtrl(object):

    def __init__(self, ethernet, channel, controller=None, robot=None,
                 max_retries=1000, max_length=1480):
        if len(filter(None, [ robot, controller])) != 1:
            raise Exception('Either robot(%s) or controller(%s) '
                            'should be defined' %
                            (robot, controller))
        else:
            self.other = filter(None, [ robot, controller])[0]
        self.ethernet = ethernet
        self.channel = channel
        self.controller = controller
        self.robot = robot
        self.max_retries = max_retries
        self.max_length = max_length
        self.read_data = list()
        self.cond = threading.Condition()
        self.local_index = random.randint(0,2**32-1)
        self.remote_index = None
        self.cookie = None
        self.ack = None
        t = threading.Thread(target=self.recv_loop)
        t.daemon = True
        t.start()
        if self.controller:
            self.send_INIT()
        elif self.robot:
            self.await_INIT()
        

    def recv_loop(self):
        ack = None
        data = None
        while True:
            fragment = Packet(self.ethernet.recv(2000))

            # Sanity check fragment
            if fragment.eth_type != 'EX':
                continue
            if fragment.source != self.other:
                continue
            if fragment.channel != self.channel:
                continue
            if fragment.cookie != 0 and fragment.cookie != self.cookie:
                continue

            # Join fragments
            if fragment.flags & flag_IS_ACK != 0:
                if fragment.frag_num == 0:
                    ack = fragment
                elif ack != None:
                    ack = ack.join(fragment)
                else:
                    ack = None
                packet = ack
            else:
                if fragment.frag_num == 0:
                    data = fragment
                elif data != None:
                    data = data.join(fragment)
                else:
                    data = None
                packet = data

            if packet == None:
                # Join failed
                continue
            if fragment.flags & flag_LAST_FRAG == 0:
                # Await more fragments
                continue
            
            if packet.flags & flag_IS_ACK != 0:
                with self.cond:
                    if packet.index == self.ack:
                        self.ack = None
                        self.cond.notify_all()
                    if packet.kind == kind_INIT and self.remote_index == None:
                        decoder = Decoder(packet.data)
                        with self.cond:
                            self.remote_index = decoder.decode_uint32()
                            self.cookie = self.remote_index ^ self.local_index
                            self.cond.notify_all()
            elif packet.kind == kind_INIT:
                remote_index = packet.index
                if self.remote_index == None:
                    # Save 
                    with self.cond:
                        self.remote_index = remote_index
                        self.cookie = self.remote_index ^ self.local_index
                        self.cond.notify_all()                        
                if remote_index == self.remote_index:
                    # ACK first INIT or its resends
                    self.send_INIT_ACK()
            elif packet.kind == kind_DATA:
                if self.remote_index != packet.index:
                    with self.cond:
                        self.remote_index = packet.index
                        self.read_data.extend(packet.data)
                        self.cond.notify_all()
                if packet.flags & flag_NEED_ACK:
                    self.send_ACK(packet)

    def retries(self, index, timeout=1):
        with self.cond:
            self.ack = index
        i = 0
        while i < self.max_retries:
            yield i
            i += 1
            with self.cond:
                if self.ack == index:
                    self.cond.wait(timeout)
                if self.ack != index:
                    raise StopIteration()
        raise Exception()

    def await_INIT(self):
        with self.cond:
            while self.cookie == None:
                self.cond.wait(1)

    def send_INIT(self):
        flags = kind_INIT | flag_NEED_ACK
        fragmenter = Fragmenter(destination=self.other,
                                channel=self.channel,
                                flags=flags,
                                cookie=0,
                                index=self.local_index)
        for i in self.retries(self.local_index):
            for f in fragmenter.fragments(max_length=self.max_length):
                self.ethernet.send(f.getvalue())
        self.local_index += 1

    def send_INIT_ACK(self):
        flags = kind_INIT | flag_IS_ACK
        fragmenter = Fragmenter(destination=self.other,
                                channel=self.channel,
                                flags=flags,
                                cookie=0,
                                index=self.remote_index)
        fragmenter.encode_uint32(self.local_index)
        for f in fragmenter.fragments(max_length=self.max_length):
            self.ethernet.send(f.getvalue())
        
    def send_ACK(self, packet):
        flags = packet.kind | flag_IS_ACK
        fragmenter = Fragmenter(destination=self.other,
                                channel=self.channel,
                                flags=flags,
                                cookie=packet.cookie,
                                index=packet.index)
        for f in fragmenter.fragments(max_length=self.max_length):
            self.ethernet.send(f.getvalue())
        
    def send_DATA_with_ack(self, data):
        flags = kind_DATA | flag_NEED_ACK
        fragmenter = Fragmenter(destination=self.other,
                                channel=self.channel,
                                flags=flags,
                                cookie=self.cookie,
                                index=self.local_index)
        fragmenter.write(data)
        for i in self.retries(self.local_index):
            for f in fragmenter.fragments(max_length=self.max_length):
                self.ethernet.send(f.getvalue())
        self.local_index += 1

    def send_DATA(self, data):
        flags = kind_DATA
        fragmenter = Fragmenter(destination=self.other,
                                channel=self.channel,
                                flags=flags,
                                cookie=self.cookie,
                                index=self.local_index)
        fragmenter.write(data)
        for f in fragmenter.fragments(max_length=self.max_length):
            self.ethernet.send(f.getvalue())
        self.local_index += 1

    def writer(self):
        class Writer:
            def __init__(self, extctrl):
                self.extctrl = extctrl
                
            def mark_begin(self, decl, value):
                self.data = ""

            def mark_end(self, decl, value):
                if value == None:
                    self.extctrl.send_DATA_with_ack(data=self.data)
                else:
                    self.extctrl.send_DATA(data=self.data)
                
            def write(self, data):
                self.data += data
                pass
                
        return Writer(self)
    
    def reader(self):
        class Reader:
            def __init__(self, extctrl):
                self.extctrl = extctrl
                
            def mark(self, decl, value):
                pass

            def read(self, count):
                with self.extctrl.cond:
                    while len(self.extctrl.read_data) == 0:
                        self.extctrl.cond.wait()
                    data = self.extctrl.read_data[0:count]
                    self.extctrl.read_data = self.extctrl.read_data[count:]
                    return ''.join(data)
                
        return Reader(self)