mdw@git.distorted.org.uk Git - userv-utils/blob - ipif/udptunnel

   1 #!/usr/bin/perl
   2 # Simple tunnel for userv-ipif tunnels.
   3 #
   4 # usage:
   5 #  udptunnel
   6 #        [ -l[<local-command/arg>] ... .
   7 #        | -e <encryption-mech>[/<encryption-parameter>...]
   8 #        | -m   (`masquerade support': subcommand gets `Wait' instead of our addr/port)
   9 #        | -d   (`dump keys': when no subcmd, spew keys rather than reading them;
  10 #                we always send keys to our subcmd if there is one)
  11 #        | -Dcrypto  (debug crypto - use with care, prints keys, packets &c on screen!)
  12 #        | -f<path-to-udptunnel-forwarder>
  13 #          ...
  14 #        ]
  15 #            <public-local-addr>,<public-local-port>
  16 #            <public-remote-addr>,<public-remote-port>
  17 #            <private-local-addr>,<private-remote-addr>,<mtu>,<proto>
  18 #            <keepalive>,<timeout>
  19 #            <extra-local-nets> <extra-remote-nets>
  20 #          [ <remote-command> [<remote-args> ...] ]
  21 #
  22 # proto may be slip or cslip
  23 #
  24 # Any <..-addr> may also be hostname
  25 #
  26 # Local addr's and ports may also be:
  27 #    `Print'     choose one ourselves and print both port and addr
  28 #    `Any'       choose one ourselves and do not print it
  29 # Remote addr's and ports may also be:
  30 #    `Wait'      wait to receive a packet before assigning address
  31 #    `Command'   run a subcommand and wait for it to tell us the values
  32 # When any addr or port is `Command' then <remote-command> must be specified.
  33 #
  34 # If <remote-command> is specified it should run udptunnel at the
  35 # remote end; it will be invoked as
  36 #    <remote-command> [ <-e arguments passed along> ]
  37 #                     <public-remote-addr'>,<public-remote-port'>
  38 #                     <public-local-addr'>,<public-local-port'>
  39 #                     <private-remote-addr>,<private-local-addr>,<mtu>,<proto>
  40 #                     <keepalive>,<timeout>
  41 #                     <extra-remote-nets> <extra-local-nets>
  42 #
  43
  44 # If it was given Print for <public-remote-foo'>, this command's first
  45 # stdout output should be the real
  46 # <public-remote-addr>,<public-remote-port> pair (and of course this
  47 # udptunnel's output will be).  It may then produce more stdout which,
  48 # if any, will be forwarded to the local end's stdout as debugging info.
  49 #
  50 # After this, if any encryption was specified, the encryption
  51 # parameters will be fed into its stdin.  See the documentation in the
  52 # mech-*.c files for details of the parameters.  udptunnel will
  53 # arrange to feed the keys fd of udptunnel-forwarder into the stdin of
  54 # the remote command.
  55 #
  56 # <public-remote-foo'> is as follows:
  57 #   <public-remote-foo>  <public-remote-foo'>
  58 #   actual addr/port     that addr/port
  59 #   `Command'            `Print'
  60 #   `Wait'               `Any'
  61 #
  62 # <public-local-foo'> is as follows:
  63 #   <public-local-foo>   <public-local-foo'>     <public-local-foo'>
  64 #                        (-m not specified)      (-m specified)
  65 #   actual addr/port     that addr/port          `Wait'
  66 #   `Wait'               the chosen address      `Wait'
  67 #   `Print'              the chosen address      `Wait'
  68 #
  69 # udptunnel will userv ipif locally, as
  70 #    userv root ipif <private-local-addr>,<private-remote-addr>,<mtu>,<proto>
  71 #                    <extra-local-nets>
  72 # or, if -l was given, userv root ipif is replaced with the argument(s)
  73 # following -l option(s) until `.'.
  74 #
  75 # udptunnel will also run udptunnel-forwarder with appropriate options
  76 #
  77 # recommended encryption parameters are:
  78 #   -e nonce                            (prepend 32 bit counter)
  79 #   -e timestamp/<max-skew>/<max-age>   (prepend 32 bit time_t, and check on receipt)
  80 #   -e pkcs5/8                          (pad as per PKCS#5 to 8-byte boundary)
  81 #   -e blowfish-cbcmac/128              (prepend CBC MAC with random IV and 128 bit key)
  82 #   -e blowfish-cbc/128                 (encrypt with CBC, random IV and 128 bit key)
  83 # where <max-skew> is perhaps 10 and <max-age> perhaps 30.
  84
  85 # Copyright (C) 1999-2000 Ian Jackson
  86 #
  87 # This is free software; you can redistribute it and/or modify it
  88 # under the terms of the GNU General Public License as published by
  89 # the Free Software Foundation; either version 2 of the License, or
  90 # (at your option) any later version.
  91 #
  92 # This program is distributed in the hope that it will be useful, but
  93 # WITHOUT ANY WARRANTY; without even the implied warranty of
  94 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  95 # General Public License for more details.
  96 #
  97 # You should have received a copy of the GNU General Public License
  98 # along with userv-utils; if not, write to the Free Software
  99 # Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 100 #
 101 # $Id$
 102
 103 use Socket;
 104 use POSIX;
 105 use Fcntl;
 106
 107 $progname= $0; $progname =~ s,.*/,,;
 108 $|=1;
 109
 110 chomp($hostname= `uname -n`);
 111 $? and die "$progname: cannot get hostname (uname failed with code $?)\n";
 112
 113 sub quit ($) { die "$progname - $hostname: fatal error: $_[0]\n"; }
 114 sub debug ($) { print "$progname - $hostname: debug: $_[0]\n"; }
 115 sub fail ($) { quit("unexpected system call failure: $_[0]: $!"); }
 116 sub warning ($) { warn "$progname - $hostname: $_[0]\n"; }
 117
 118 sub eat_addr_port ($) {
 119     my ($x) = @_;
 120     @ARGV or quit("<addr>,<port> missing");
 121     $_= shift(@ARGV);
 122     (m/^$x,/i && m/^[a-z]/ || m/,$x$/i && m/,[a-z]/)
 123         and warning("$_: use Mixed Case for special values");
 124     m/^([0-9a-z][0-9a-z-+.]+|$x)\,(\d+|$x)$/
 125         or quit("$_: <host/addr>,<port> bad syntax".
 126                 (m/[A-Z]/ ? ' (use lowercase for hostnames)' : ''));
 127     return ($1,$2);
 128 }
 129 sub conv_host_addr ($) {
 130     my ($s,$r,@h) = @_;
 131     return INADDR_ANY() if $s =~ m/^[A-Z][a-z]/;
 132     return $r if defined($r= inet_aton($s));
 133     @h= gethostbyname($s) or quit("$s: cannot get address");
 134     $h[2] eq &AF_INET or quit("$s: address is not IPv4");
 135     @h < 5 or quit("$s: name maps to no addresses");
 136     $r= $h[4];
 137     @h == 5 or warning("$s: name has several addresses, using ".inet_ntoa($r));
 138     return $r;
 139 }
 140 sub conv_port_number ($) {
 141     my ($s,$r) = @_;
 142     return 0 if $s =~ m/^[A-Z][a-z]/;
 143     $r= $s+0;
 144     $r>0 && $r<65536 or quit("$s: port out of range");
 145     return $r;
 146 }
 147 sub show_addr ($) {
 148     my ($s,@s) = @_;
 149     @s= unpack_sockaddr_in($s);
 150     return inet_ntoa($s[1]);
 151 }
 152 sub show_port ($) {
 153     my ($s,@s) = @_;
 154     @s= unpack_sockaddr_in($s);
 155     return $s[0];
 156 }
 157 sub show_addr_port ($) {
 158     my ($s) = @_;
 159     return show_addr($s).','.show_port($s);
 160 }
 161 sub arg_value ($$) {
 162     my ($val,$opt) = @_;
 163     $_= '-';
 164     return $val if length $val;
 165     @ARGV or quit("$opt needs value");
 166     return shift @ARGV;
 167 }
 168
 169 $|=1;
 170
 171 @lcmd= ();
 172 @encryption= ();
 173 $masq= 0;
 174 $dump= 0;
 175 $fcmd= 'udptunnel-forwarder';
 176 $xfwdopts= '';
 177
 178 while ($ARGV[0] =~ m/^-/) {
 179     $_= shift @ARGV;
 180     last if m/^--?$/;
 181     while (!m/^-$/) {
 182         if (s/^-l//) {
 183             push @lcmd,$_ if length;
 184             while (@ARGV && ($_= shift @ARGV) ne '.') { push @lcmd, $_; }
 185             $_= '-'
 186         } elsif (s/^-f//) {
 187             $fcmd= arg_value($_,'-f');
 188         } elsif (s/^-e//) {
 189             $encrarg= arg_value($_,'-e');
 190             push @remoteopts, "-e$encrarg";
 191             @thisencryption= split m#/#, $encrarg;
 192             $thisencryption[0] =~ s/^/\!/;
 193             push @encryption, @thisencryption;
 194         } elsif (s/^-m/-/) {
 195             $masq= 1;
 196         } elsif (s/^-d/-/) {
 197             $dump= 1;
 198         } elsif (s/^-Dcrypto$/-/) {
 199             $xfwdopts.= 'K';
 200             push @remoteopts, '-Dcrypto';
 201         } else {
 202             quit("unknown option \`$_'");
 203         }
 204     }
 205 }
 206
 207 # Variables \$[lr]a?p?(|s|d|r)
 208 # Local/Remote  Address&/Port
 209 #    actualvalue/Specified/Displaypassdown/fromRemote/passtoForwarder
 210 #
 211 ($las,$lps)= eat_addr_port('Print|Any');
 212 $la= conv_host_addr($las);
 213 $lp= conv_port_number($lps);
 214 $ls= pack_sockaddr_in $lp,$la;
 215
 216 ($ras,$rps)= eat_addr_port('Wait|Command');
 217 $ra= conv_host_addr($ras);
 218 $rp= conv_port_number($rps);
 219 $rs= pack_sockaddr_in $rp,$ra;
 220
 221 $_= shift @ARGV;
 222 m/^([.0-9]+),([.0-9]+),(\d+),(slip|cslip)$/
 223     or quit("lvaddr,rvaddr,mtu,proto missing or bad syntax or proto not [c]slip");
 224 ($lva,$rva,$mtu,$proto) = ($1,$2,$3,$4);
 225
 226 $_= shift @ARGV;
 227 m/^(\d+),(\d+)$/ or quit("keepalive,timeout missing or bad syntax");
 228 ($keepalive,$timeout)= ($1,$2);
 229 $keepalive && ($timeout > $keepalive*2) or quit("timeout must be < 2*keepalive")
 230     if $timeout;
 231
 232 # Variables \$[lr]exn
 233 # Local/Remote Extra Nets
 234 $lexn= shift @ARGV;
 235 $rexn= shift @ARGV;
 236
 237 defined($udp= getprotobyname('udp')) or fail("getprotobyname udp");
 238
 239 socket(L,PF_INET,SOCK_DGRAM,$udp) or fail("socket");
 240 bind(L,$ls) or quit("bind failed: $!");
 241 defined($ls= getsockname(L)) or fail("getsockname");
 242 $lad= show_addr($ls);
 243 $lpd= show_port($ls);
 244 $lapd= "$lad,$lpd";
 245
 246 print "$lapd\n" or fail("print addr/port") if ($las eq 'Print' || $lps eq 'Print');
 247
 248 $rapcmd= ($ras eq 'Command' || $rps eq 'Command');
 249 quit("need remote-command if Command for remote addr/port") if $rapcmd && !@ARGV;
 250
 251 sub xform_remote ($$) {
 252     my ($showed,$spec) = @_;
 253     return 'Print' if $spec eq 'Command';
 254     return 'Any' if $spec eq 'Wait';
 255     return $showed;
 256 }
 257
 258 if (@ARGV) {
 259     warning("-d specified with remote command, ignoring") if $dump;
 260     $dump= 1;
 261
 262     $rad= xform_remote(show_addr($rs),$ras);
 263     $rpd= xform_remote(show_port($rs),$rps);
 264     @rcmd= (@ARGV,
 265             @remoteopts,
 266             "$rad,$rpd",
 267             $masq ? 'Wait,Wait' : $lapd,
 268             "$rva,$lva,$mtu,$proto",
 269             "$keepalive,$timeout",
 270             $rexn, $lexn);
 271     debug("remote command @rcmd");
 272
 273     if ($rapcmd) {
 274         pipe(RAPREAD,RCMDREADSUB) or fail("pipe");
 275         select(RCMDREADSUB); $|=1; select(STDOUT);
 276     }
 277     pipe(RCMDWRITESUB,DUMPKEYS) or fail("pipe");
 278     defined($c_rcmd= fork) or fail("fork for remote");
 279     if (!$c_rcmd) {
 280         open STDIN, "<&RCMDWRITESUB" or fail("reopen stdin for remote command");
 281         open STDOUT, ">&RCMDREADSUB" or fail("reopen stdout for remote command")
 282             if $rapcmd;
 283         close RAPREAD if $rapcmd;
 284         close DUMPKEYS;
 285         close RCMDWRITESUB;
 286         close RCMDREADSUB;
 287         close L;
 288         exec @rcmd; fail("failed to execute remote command $rcmd[0]");
 289     }
 290     close RCMDWRITESUB;
 291
 292     if ($rapcmd) {
 293         close RCMDREADSUB if $rapcmd;
 294         $!=0; $_= <RAPREAD>; $e="$!";
 295
 296         defined($c_catremdebug= fork) or fail("fork for cat remote debug");
 297         if (!$c_catremdebug) {
 298             open(STDIN,"<&RAPREAD") or fail("redirect remote debug");
 299             close RAPREAD;
 300             close DUMPKEYS;
 301             close L;
 302             exec "cat"; fail("execute cat");
 303         }
 304         close RAPREAD;
 305
 306         if (!length) {
 307             close DUMPKEYS;
 308             waitpid $c_rcmd,0 or fail("wait for remote command");
 309             quit($? ? "remote command failed (code $?)" :
 310                  $e ? "read error from remote command: $e" :
 311                  "no details received from remote");
 312         }
 313         chomp;
 314         m/^([.0-9]+)\,(\d+)$/ or quit("invalid details from remote end: \`$_'");
 315         ($rar,$rpr) = ($1,$2);
 316         $ra= conv_host_addr($rar);
 317         $rp= conv_port_number($rpr);
 318     }
 319 } elsif ($dump) {
 320     open DUMPKEYS, ">&STDOUT" or fail("reopen stdout for key material");
 321     $dump= 1;
 322 } else {
 323     open DUMPKEYS, "<&STDIN" or fail("reopen stdout for key material");
 324 }
 325
 326 $rs= pack_sockaddr_in $rp,$ra;
 327
 328 if ($ras eq 'Wait' || $rps eq 'Wait') {
 329     @rapf= ('');
 330     $rapd= ('Wait,Wait');
 331 } else {
 332     @rapf= (show_addr($rs), show_port($rs));
 333     $rapd= show_addr_port($rs);
 334 }
 335 @lcmd= qw(userv root ipif) unless @lcmd;
 336
 337 debug("using remote $rapd local $lapd");
 338 push @lcmd, ("$lva,$rva,$mtu,$proto",$lexn);
 339 debug("local command @lcmd.");
 340
 341 pipe(UR,UW) or fail("up pipe");
 342 pipe(DR,DW) or fail("down pipe");
 343
 344 defined($c_lcmd= fork) or fail("fork for local command");
 345 if (!$c_lcmd) {
 346     close UR; close DW;
 347     open(STDIN,"<&DR") or fail("reopen stdin for packets");
 348     open(STDOUT,">&UW") or fail("reopen stdout for packets");
 349     exec @lcmd;
 350     quit("cannot execute $lcmd[0]: $!");
 351 }
 352 close UW;
 353 close DR;
 354
 355 $xfwdopts.= 'w' if $dump;
 356
 357 @fcmd= ($fcmd, $xfwdopts,
 358         fileno(L), fileno(DW), fileno(UR), fileno(DUMPKEYS),
 359         $mtu, $keepalive, $timeout,
 360         @rapf,
 361         @encryption);
 362 debug("forwarding command @fcmd.");
 363
 364 defined($c_fwd= fork) or fail("fork for udptunnel-forwarder");
 365 if (!$c_fwd) {
 366     foreach $fd (qw(L DW UR DUMPKEYS)) {
 367         fcntl($fd, F_SETFD, 0) or fail("set no-close-on-exec $fd");
 368     }
 369     exec @fcmd; fail("cannot execute $fcmd[0]");
 370 }
 371
 372 close L;
 373 close DUMPKEYS;
 374 close UR;
 375 close DW;
 376
 377 %procs= ($c_fwd, 'forwarder',
 378          $c_lcmd, 'local command');
 379 $procs{$c_rcmd}= 'remote command' if $c_rcmd;
 380 $procs{$c_catremdebug}= 'debug cat' if $c_catremdebug;
 381
 382 $estatus= 0;
 383
 384 while (keys %procs) {
 385     ($c= wait) >0 or
 386         fail("wait failed (expecting ". join('; ',keys %procs). ")");
 387     $status= $?;
 388     warning("unexpected child reaped: pid $c, code $status"), next
 389         unless exists $procs{$c};
 390     $str= $procs{$c};
 391     delete $procs{$c};
 392     $status ? warning("subprocess $str failed with code $status")
 393         : debug("subprocess $str finished");
 394     if ($c==$c_lcmd || $c==$c_fwd || $c==$c_rcmd) {
 395         kill 15, grep (exists $procs{$_}, $c_fwd, $c_rcmd);
 396     }
 397     $estatus=1 unless $c == $c_catremdebug;
 398 }
 399
 400 debug("all processes terminated, exiting with status $estatus");
 401
 402 exit $estatus;