src/nepi/testbeds/planetlab/scripts/tun_connect.py

   1 import sys
   2
   3 import socket
   4 import fcntl
   5 import os
   6 import select
   7
   8 import struct
   9 import ctypes
  10 import optparse
  11 import threading
  12 import subprocess
  13 import re
  14 import functools
  15
  16 tun_name = 'tun0'
  17 tun_path = '/dev/net/tun'
  18 hostaddr = socket.gethostbyname(socket.gethostname())
  19
  20 usage = "usage: %prog [options] <remote-endpoint>"
  21
  22 parser = optparse.OptionParser(usage=usage)
  23
  24 parser.add_option(
  25     "-i", "--iface", dest="tun_name", metavar="DEVICE",
  26     default = "tun0",
  27     help = "TUN/TAP interface to tap into")
  28 parser.add_option(
  29     "-d", "--tun-path", dest="tun_path", metavar="PATH",
  30     default = "/dev/net/tun",
  31     help = "TUN/TAP device file path or file descriptor number")
  32 parser.add_option(
  33     "-p", "--port", dest="port", metavar="PORT", type="int",
  34     default = 15000,
  35     help = "Peering TCP port to connect or listen to.")
  36
  37 parser.add_option(
  38     "-m", "--mode", dest="mode", metavar="MODE",
  39     default = "none",
  40     help =
  41         "Set mode. One of none, tun, tap, pl-tun, pl-tap. In any mode except none, a TUN/TAP will be created "
  42         "by using the proper interface (tunctl for tun/tap, /vsys/fd_tuntap.control for pl-tun/pl-tap), "
  43         "and it will be brought up (with ifconfig for tun/tap, with /vsys/vif_up for pl-tun/pl-tap). You have "
  44         "to specify an VIF_ADDRESS and VIF_MASK in any case (except for none).")
  45 parser.add_option(
  46     "-A", "--vif-address", dest="vif_addr", metavar="VIF_ADDRESS",
  47     default = None,
  48     help =
  49         "See mode. This specifies the VIF_ADDRESS, "
  50         "the IP address of the virtual interface.")
  51 parser.add_option(
  52     "-M", "--vif-mask", dest="vif_mask", type="int", metavar="VIF_MASK",
  53     default = None,
  54     help =
  55         "See mode. This specifies the VIF_MASK, "
  56         "a number indicating the network type (ie: 24 for a C-class network).")
  57 parser.add_option(
  58     "-S", "--vif-snat", dest="vif_snat",
  59     action = "store_true",
  60     default = False,
  61     help = "See mode. This specifies whether SNAT will be enabled for the virtual interface. " )
  62 parser.add_option(
  63     "-P", "--vif-pointopoint", dest="vif_pointopoint",  metavar="DST_ADDR",
  64     default = None,
  65     help =
  66         "See mode. This specifies the remote endpoint's virtual address, "
  67         "for point-to-point routing configuration. "
  68         "Not supported by PlanetLab" )
  69 parser.add_option(
  70     "-Q", "--vif-txqueuelen", dest="vif_txqueuelen", metavar="SIZE", type="int",
  71     default = None,
  72     help =
  73         "See mode. This specifies the interface's transmission queue length. " )
  74
  75 (options, remaining_args) = parser.parse_args(sys.argv[1:])
  76
  77
  78 ETH_P_ALL = 0x00000003
  79 ETH_P_IP = 0x00000800
  80 TUNSETIFF = 0x400454ca
  81 IFF_NO_PI = 0x00001000
  82 IFF_TAP = 0x00000002
  83 IFF_TUN = 0x00000001
  84 IFF_VNET_HDR = 0x00004000
  85 TUN_PKT_STRIP = 0x00000001
  86 IFHWADDRLEN = 0x00000006
  87 IFNAMSIZ = 0x00000010
  88 IFREQ_SZ = 0x00000028
  89 FIONREAD = 0x0000541b
  90
  91 def ifnam(x):
  92     return x+'\x00'*(IFNAMSIZ-len(x))
  93
  94 def ifreq(iface, flags):
  95     # ifreq contains:
  96     #   char[IFNAMSIZ] : interface name
  97     #   short : flags
  98     #   <padding>
  99     ifreq = ifnam(iface)+struct.pack("H",flags);
 100     ifreq += '\x00' * (len(ifreq)-IFREQ_SZ)
 101     return ifreq
 102
 103 def tunopen(tun_path, tun_name):
 104     if tun_path.isdigit():
 105         # open TUN fd
 106         print >>sys.stderr, "Using tun:", tun_name, "fd", tun_path
 107         tun = os.fdopen(int(tun_path), 'r+b', 0)
 108     else:
 109         # open TUN path
 110         print >>sys.stderr, "Using tun:", tun_name, "at", tun_path
 111         tun = open(tun_path, 'r+b', 0)
 112
 113         # bind file descriptor to the interface
 114         fcntl.ioctl(tun.fileno(), TUNSETIFF, ifreq(tun_name, IFF_NO_PI|IFF_TUN))
 115
 116     return tun
 117
 118 def tunclose(tun_path, tun_name, tun):
 119     if tun_path.isdigit():
 120         # close TUN fd
 121         os.close(int(tun_path))
 122         tun.close()
 123     else:
 124         # close TUN object
 125         tun.close()
 126
 127 def tuntap_alloc(kind, tun_path, tun_name):
 128     args = ["tunctl"]
 129     if kind == "tun":
 130         args.append("-n")
 131     if tun_name:
 132         args.append("-t")
 133         args.append(tun_name)
 134     proc = subprocess.Popen(args, stdout=subprocess.PIPE)
 135     out,err = proc.communicate()
 136     if proc.wait():
 137         raise RuntimeError, "Could not allocate %s device" % (kind,)
 138
 139     match = re.search(r"Set '(?P<dev>(?:tun|tap)[0-9]*)' persistent and owned by .*", out, re.I)
 140     if not match:
 141         raise RuntimeError, "Could not allocate %s device - tunctl said: %s" % (kind, out)
 142
 143     tun_name = match.group("dev")
 144     print >>sys.stderr, "Allocated %s device: %s" % (kind, tun_name)
 145
 146     return tun_path, tun_name
 147
 148 def tuntap_dealloc(tun_path, tun_name):
 149     args = ["tunctl", "-d", tun_name]
 150     proc = subprocess.Popen(args, stdout=subprocess.PIPE)
 151     out,err = proc.communicate()
 152     if proc.wait():
 153         print >> sys.stderr, "WARNING: error deallocating %s device" % (tun_name,)
 154
 155 def nmask_to_dot_notation(mask):
 156     mask = hex(((1 << mask) - 1) << (32 - mask)) # 24 -> 0xFFFFFF00
 157     mask = mask[2:] # strip 0x
 158     mask = mask.decode("hex") # to bytes
 159     mask = '.'.join(map(str,map(ord,mask))) # to 255.255.255.0
 160     return mask
 161
 162 def vif_start(tun_path, tun_name):
 163     args = ["ifconfig", tun_name, options.vif_addr,
 164             "netmask", nmask_to_dot_notation(options.vif_mask),
 165             "-arp" ]
 166     if options.vif_pointopoint:
 167         args.extend(["pointopoint",options.vif_pointopoint])
 168     if options.vif_txqueuelen is not None:
 169         args.extend(["txqueuelen",str(options.vif_txqueuelen)])
 170     args.append("up")
 171     proc = subprocess.Popen(args, stdout=subprocess.PIPE)
 172     out,err = proc.communicate()
 173     if proc.wait():
 174         raise RuntimeError, "Error starting virtual interface"
 175
 176     if options.vif_snat:
 177         # set up SNAT using iptables
 178         # TODO: stop vif on error.
 179         #   Not so necessary since deallocating the tun/tap device
 180         #   will forcibly stop it, but it would be tidier
 181         args = [ "iptables", "-t", "nat", "-A", "POSTROUTING",
 182                  "-s", "%s/%d" % (options.vif_addr, options.vif_mask),
 183                  "-j", "SNAT",
 184                  "--to-source", hostaddr, "--random" ]
 185         proc = subprocess.Popen(args, stdout=subprocess.PIPE)
 186         out,err = proc.communicate()
 187         if proc.wait():
 188             raise RuntimeError, "Error setting up SNAT"
 189
 190 def vif_stop(tun_path, tun_name):
 191     if options.vif_snat:
 192         # set up SNAT using iptables
 193         args = [ "iptables", "-t", "nat", "-D", "POSTROUTING",
 194                  "-s", "%s/%d" % (options.vif_addr, options.vif_mask),
 195                  "-j", "SNAT",
 196                  "--to-source", hostaddr, "--random" ]
 197         proc = subprocess.Popen(args, stdout=subprocess.PIPE)
 198         out,err = proc.communicate()
 199
 200     args = ["ifconfig", tun_name, "down"]
 201     proc = subprocess.Popen(args, stdout=subprocess.PIPE)
 202     out,err = proc.communicate()
 203     if proc.wait():
 204         print >>sys.stderr, "WARNING: error stopping virtual interface"
 205
 206
 207 def pl_tuntap_alloc(kind, tun_path, tun_name):
 208     tunalloc_so = ctypes.cdll.LoadLibrary("./tunalloc.so")
 209     c_tun_name = ctypes.c_char_p("\x00"*IFNAMSIZ) # the string will be mutated!
 210     kind = {"tun":IFF_TUN,
 211             "tap":IFF_TAP}[kind]
 212     fd = tunalloc_so.tun_alloc(kind, c_tun_name)
 213     name = c_tun_name.value
 214     return str(fd), name
 215
 216 def pl_vif_start(tun_path, tun_name):
 217     stdin = open("/vsys/vif_up.in","w")
 218     stdout = open("/vsys/vif_up.out","r")
 219     stdin.write(tun_name+"\n")
 220     stdin.write(options.vif_addr+"\n")
 221     stdin.write(str(options.vif_mask)+"\n")
 222     if options.vif_snat:
 223         stdin.write("snat=1\n")
 224     if options.vif_txqueuelen is not None:
 225         stdin.write("txqueuelen=%d\n" % (options.vif_txqueuelen,))
 226     stdin.close()
 227     out = stdout.read()
 228     stdout.close()
 229     if out.strip():
 230         print >>sys.stderr, out
 231
 232
 233 def ipfmt(ip):
 234     ipbytes = map(ord,ip.decode("hex"))
 235     return '.'.join(map(str,ipbytes))
 236
 237 def formatPacket(packet):
 238     packet = packet.encode("hex")
 239     return '-'.join( (
 240         packet[0:1], #version
 241         packet[1:2], #header length
 242         packet[2:4], #diffserv/ECN
 243         packet[4:8], #total length
 244         packet[8:12], #ident
 245         packet[12:16], #flags/fragment offs
 246         packet[16:18], #ttl
 247         packet[18:20], #ip-proto
 248         packet[20:24], #checksum
 249         ipfmt(packet[24:32]), # src-ip
 250         ipfmt(packet[32:40]), # dst-ip
 251         packet[40:48] if (int(packet[1]) > 5) else "", # options
 252         packet[48:] if (int(packet[1]) > 5) else packet[40:], # payload
 253     ) )
 254
 255 def packetReady(buf):
 256     if len(buf) < 4:
 257         return False
 258     _,totallen = struct.unpack('HH',buf[:4])
 259     totallen = socket.htons(totallen)
 260     return len(buf) >= totallen
 261
 262 def pullPacket(buf):
 263     _,totallen = struct.unpack('HH',buf[:4])
 264     totallen = socket.htons(totallen)
 265     return buf[:totallen], buf[totallen:]
 266
 267 def etherStrip(buf):
 268     if len(buf) < 14:
 269         return buf
 270     if buf[12:14] == '\x08\x10' and buf[16:18] == '\x08\x00':
 271         # tagged ethernet frame
 272         return buf[18:]
 273     elif buf[12:14] == '\x08\x00':
 274         # untagged ethernet frame
 275         return buf[14:]
 276     else:
 277         return buf
 278
 279 def etherWrap(packet):
 280     return (
 281         "\x00"*6*2 # bogus src and dst mac
 282         +"\x08\x00" # IPv4
 283         +packet # payload
 284         +"\x00"*4 # bogus crc
 285     )
 286
 287 def piStrip(buf):
 288     if len(buf) < 4:
 289         return buf
 290     else:
 291         return buf[4:]
 292
 293 def piWrap(buf):
 294     return (
 295         "\x00\x00\x08\x00" # PI: 16 bits flags, 16 bits proto
 296         +buf
 297     )
 298
 299 abortme = False
 300 def tun_fwd(tun, remote):
 301     global abortme
 302
 303     # in PL mode, we cannot strip PI structs
 304     # so we'll have to handle them
 305     with_pi = options.mode.startswith('pl-')
 306     ether_mode = tun_name.startswith('tap')
 307
 308     # Limited frame parsing, to preserve packet boundaries.
 309     # Which is needed, since /dev/net/tun is unbuffered
 310     fwbuf = ""
 311     bkbuf = ""
 312     while not abortme:
 313         wset = []
 314         if packetReady(bkbuf):
 315             wset.append(tun)
 316         if packetReady(fwbuf):
 317             wset.append(remote)
 318         rdrdy, wrdy, errs = select.select((tun,remote),wset,(tun,remote),1)
 319
 320         # check for errors
 321         if errs:
 322             break
 323
 324         # check to see if we can write
 325         if remote in wrdy and packetReady(fwbuf):
 326             packet, fwbuf = pullPacket(fwbuf)
 327             os.write(remote.fileno(), packet)
 328             print >>sys.stderr, '>', formatPacket(packet)
 329             if ether_mode:
 330                 # strip ethernet crc
 331                 fwbuf = fwbuf[4:]
 332         if tun in wrdy and packetReady(bkbuf):
 333             packet, bkbuf = pullPacket(bkbuf)
 334             formatted = formatPacket(packet)
 335             if ether_mode:
 336                 packet = etherWrap(packet)
 337             if with_pi:
 338                 packet = piWrap(packet)
 339             os.write(tun.fileno(), packet)
 340             print >>sys.stderr, '<', formatted
 341
 342         # check incoming data packets
 343         if tun in rdrdy:
 344             packet = os.read(tun.fileno(),2000) # tun.read blocks until it gets 2k!
 345             if with_pi:
 346                 packet = piStrip(packet)
 347             fwbuf += packet
 348             if ether_mode:
 349                 fwbuf = etherStrip(fwbuf)
 350         if remote in rdrdy:
 351             packet = os.read(remote.fileno(),2000) # remote.read blocks until it gets 2k!
 352             bkbuf += packet
 353
 354
 355
 356 nop = lambda tun_path, tun_name : (tun_path, tun_name)
 357 MODEINFO = {
 358     'none' : dict(alloc=nop,
 359                   tunopen=tunopen, tunclose=tunclose,
 360                   dealloc=nop,
 361                   start=nop,
 362                   stop=nop),
 363     'tun'  : dict(alloc=functools.partial(tuntap_alloc, "tun"),
 364                   tunopen=tunopen, tunclose=tunclose,
 365                   dealloc=tuntap_dealloc,
 366                   start=vif_start,
 367                   stop=vif_stop),
 368     'tap'  : dict(alloc=functools.partial(tuntap_alloc, "tap"),
 369                   tunopen=tunopen, tunclose=tunclose,
 370                   dealloc=tuntap_dealloc,
 371                   start=vif_start,
 372                   stop=vif_stop),
 373     'pl-tun'  : dict(alloc=functools.partial(pl_tuntap_alloc, "tun"),
 374                   tunopen=tunopen, tunclose=tunclose,
 375                   dealloc=nop,
 376                   start=pl_vif_start,
 377                   stop=nop),
 378     'pl-tap'  : dict(alloc=functools.partial(pl_tuntap_alloc, "tap"),
 379                   tunopen=tunopen, tunclose=tunclose,
 380                   dealloc=nop,
 381                   start=pl_vif_start,
 382                   stop=nop),
 383 }
 384
 385 tun_path = options.tun_path
 386 tun_name = options.tun_name
 387
 388 modeinfo = MODEINFO[options.mode]
 389
 390 # be careful to roll back stuff on exceptions
 391 tun_path, tun_name = modeinfo['alloc'](tun_path, tun_name)
 392 try:
 393     modeinfo['start'](tun_path, tun_name)
 394     try:
 395         tun = modeinfo['tunopen'](tun_path, tun_name)
 396     except:
 397         modeinfo['stop'](tun_path, tun_name)
 398         raise
 399 except:
 400     modeinfo['dealloc'](tun_path, tun_name)
 401     raise
 402
 403
 404 try:
 405     # connect to remote endpoint
 406     if remaining_args and not remaining_args[0].startswith('-'):
 407         print >>sys.stderr, "Connecting to: %s:%d" % (remaining_args[0],options.port)
 408         rsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
 409         rsock.connect((remaining_args[0],options.port))
 410     else:
 411         print >>sys.stderr, "Listening at: %s:%d" % (hostaddr,options.port)
 412         lsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
 413         lsock.bind((hostaddr,options.port))
 414         lsock.listen(1)
 415         rsock,raddr = lsock.accept()
 416     remote = os.fdopen(rsock.fileno(), 'r+b', 0)
 417
 418     print >>sys.stderr, "Connected"
 419
 420     tun_fwd(tun, remote)
 421 finally:
 422     try:
 423         print >>sys.stderr, "Shutting down..."
 424     except:
 425         # In case sys.stderr is broken
 426         pass
 427
 428     # tidy shutdown in every case - swallow exceptions
 429     try:
 430         modeinfo['tunclose'](tun_path, tun_name, tun)
 431     except:
 432         pass
 433
 434     try:
 435         modeinfo['stop'](tun_path, tun_name)
 436     except:
 437         pass
 438
 439     try:
 440         modeinfo['dealloc'](tun_path, tun_name)
 441     except:
 442         pass
 443
 444