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 #            <public-local-host/addr>,<public-local-port>
   8 #            <public-remote-host/addr>,<public-remote-port>
   9 #            <private-local-addr>,<private-remote-addr>,<mtu>,<proto>
  10 #            <keepalive>,<timeout>
  11 #            <extra-local-nets> <extra-remote-nets>
  12 #          [ <remote-command> [<remote-args> ...] ]
  13 #
  14 # <local-public-port> may be number or `print' or `silent'
  15 #
  16 # <remote-public-port> may number or `command', in which case
  17 # <remote-command> must be specified and should run udptunnel at the
  18 # remote end; it will be invoked as
  19 #    <remote-command> <public-remote-host/addr>,print
  20 #                     <public-local-addr>,<public-local-port>
  21 #                     <private-remote-addr>,<private-local-addr>,<mtu>,<proto>
  22 #                     <keepalive>,<timeout>
  23 #                     <extra-remote-nets> <extra-local-nets>
  24 #
  25 # udptunnel will userv ipif locally, as
  26 #    userv root ipif <private-local-addr>,<private-remote-addr>,<mtu>,<proto>
  27 #                    <extra-local-nets>
  28 # or, if -lc was given, userv root ipif is replaced with the argument(s) to
  29 # successive -lc options.
  30
  31 # Copyright (C) 1999 Ian Jackson
  32 #
  33 # This is free software; you can redistribute it and/or modify it
  34 # under the terms of the GNU General Public License as published by
  35 # the Free Software Foundation; either version 2 of the License, or
  36 # (at your option) any later version.
  37 #
  38 # This program is distributed in the hope that it will be useful, but
  39 # WITHOUT ANY WARRANTY; without even the implied warranty of
  40 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  41 # General Public License for more details.
  42 #
  43 # You should have received a copy of the GNU General Public License
  44 # along with userv-utils; if not, write to the Free Software
  45 # Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  46 #
  47 # $Id: udptunnel,v 1.8 1999/11/09 22:35:41 ian Exp $
  48
  49 use Socket;
  50 use POSIX;
  51 use Fcntl;
  52
  53 $progname= $0; $progname =~ s,.*/,,;
  54 $|=1;
  55
  56 chomp($hostname= `uname -n`);
  57 $? and die "$progname: cannot get hostname (uname failed with code $?)\n";
  58
  59 sub quit ($) { die "$progname - $hostname: fatal error: $_[0]\n"; }
  60 sub debug ($) { print "$progname - $hostname: debug: $_[0]\n"; }
  61 sub fail ($) { quit("unexpected system call failure: $_[0]: $!\n"); }
  62 sub warning ($) { warn "$progname - $hostname: $_[0]\n"; }
  63
  64 sub eat_addr_port ($) {
  65     my ($x) = @_;
  66     @ARGV or quit("<host/addr>,<port> missing");
  67     $_= shift(@ARGV);
  68     $_ =~ m/^([^,]+)\,(\d+|$x)$/ or quit("$_: <host/addr>,<port> bad syntax");
  69     return ($1,$2);
  70 }
  71 sub conv_host_addr ($) {
  72     my ($s,$r) = @_;
  73     defined($r= inet_aton($s)) or quit("$s: cannot convert to address");
  74     return $r;
  75 }
  76 sub conv_port_number ($) {
  77     my ($s,$r) = @_;
  78     if ($s =~ m/\d/) {
  79         $r= $s+0;
  80         $r>0 && $r<65536 or quit("$s: port out of range");
  81     } else {
  82         $r= 0;
  83     }
  84     return $r;
  85 }
  86 sub show_addr_port ($) {
  87     my ($s,@s) = @_;
  88     @s= unpack_sockaddr_in($s);
  89     return inet_ntoa($s[1]).','.$s[0];
  90 }
  91
  92 @lcmd= ();
  93
  94 while ($ARGV[0] =~ m/^-/) {
  95     $_= shift @ARGV;
  96     last if $_ eq '--';
  97     if (s/^-l//) {
  98         push @lcmd,$_ if length;
  99         while (@ARGV && ($_= shift @ARGV) ne '-') { push @lcmd, $_; }
 100     } else {
 101         quit("unknown option \`$_'");
 102     }
 103 }
 104
 105 ($las,$lps)= eat_addr_port('print|silent');
 106 $la= conv_host_addr($las);
 107 $lp= conv_port_number($lps);
 108 $ls= pack_sockaddr_in $lp,$la;
 109
 110 ($ras,$rps)= eat_addr_port('command');
 111 $rp= conv_port_number($rps);
 112 $ra= $rps eq 'command' ? '' : conv_host_addr($ras);
 113
 114 $_= shift @ARGV;
 115 m/^([.0-9]+),([.0-9]+),(\d+),(slip|cslip)$/
 116     or quit("lvaddr,rvaddr,mtu,proto missing or bad syntax or proto not [c]slip");
 117 ($lva,$rva,$mtu,$proto) = ($1,$2,$3,$4);
 118
 119 $_= shift @ARGV;
 120 m/^(\d+),(\d+)$/ or quit("keepalive,timeout missing or bad syntax");
 121 ($keepalive,$timeout)= ($1,$2);
 122 $keepalive && ($timeout > $keepalive*2) or quit("timeout must be < 2*keepalive")
 123     if $timeout;
 124
 125 $lepn= shift @ARGV;
 126 $repn= shift @ARGV;
 127
 128 alarm($timeout);
 129
 130 defined($udp= getprotobyname('udp')) or fail("getprotobyname udp");
 131
 132 socket(L,PF_INET,SOCK_DGRAM,$udp) or fail("socket");
 133 bind(L,$ls) or quit("bind failed: $!");
 134 defined($ls= getsockname(L)) or fail("getsockname");
 135 $lsp= show_addr_port($ls);
 136
 137 if ($rps eq 'command') {
 138     quit("when using ,command for remote, must supply command") unless @ARGV;
 139     @rcmd= (@ARGV, "$ras,print", "$lsp", "$rva,$lva,$mtu,$proto",
 140             "$keepalive,$timeout", $repn, $lepn);
 141     debug("remote command @rcmd");
 142     defined($c= open C,"-|") or fail("fork for remote");
 143     if (!$c) {
 144         exec @rcmd; die "$progname: error: failed to execute $rcmd[0]: $!\n";
 145     }
 146     $_= <C>;
 147     if (!length) {
 148         close C;
 149         quit($? ? "remote command failed (code $?)" : "no details received from remote");
 150     }
 151     chomp;
 152     m/^([.0-9]+)\,(\d+)$/ or quit("invalid details from remote end ($_)");
 153     ($ras,$rps) = ($1,$2);
 154     $ra= conv_host_addr($ras);
 155     $rp= conv_port_number($rps);
 156     defined($c2= fork) or fail("fork for cat");
 157     if (!$c2) {
 158         open(STDIN,"<&C") or fail("redirect remote pipe to stdin");
 159         close C;
 160         exec "cat"; fail("execute cat");
 161     }
 162 } else {
 163     quit("when not using ,command for remote, must not supply command") if @ARGV;
 164 }
 165
 166 $rs= pack_sockaddr_in $rp,$ra;
 167 $rsp= show_addr_port($rs);
 168
 169 if ($lps eq 'print') { print($lsp,"\n") or quit("write port to stdout: $!"); }
 170
 171 @lcmd= qw(userv root ipif) unless @lcmd;
 172
 173 debug("using remote $rsp local $lsp");
 174 push @lcmd, ("$lva,$rva,$mtu,$proto",$lepn);
 175 debug("local command @lcmd");
 176
 177 pipe(UR,UW) or fail("up pipe");
 178 pipe(DR,DW) or fail("down pipe");
 179
 180 defined($c3= fork) or fail("fork for ipif");
 181 if (!$c3) {
 182     close UR; close DW;
 183     open(STDIN,"<&DR") or fail("reopen stdin for packets");
 184     open(STDOUT,">&UW") or fail("reopen stdout for packets");
 185     exec @lcmd;
 186     quit("cannot execute $lcmd[0]: $!");
 187 }
 188 close UW;
 189 close DR;
 190
 191 $upyet= 0;
 192 $downyet= 0;
 193
 194 $wantreadfds='';
 195 vec($wantreadfds,fileno(UR),1)= 1;
 196 vec($wantreadfds,fileno(L),1)= 1;
 197
 198 sub nonblock ($) {
 199     my ($fh,$fl) = @_;
 200     ($fl= fcntl($fh,F_GETFL,0)) or fail("nonblock F_GETFL");
 201     $fl |= O_NONBLOCK;
 202     fcntl($fh, F_SETFL, $fl) or fail("nonblock F_SETFL");
 203 }
 204
 205 nonblock('UR');
 206 nonblock('L');
 207
 208 $upbuf= '';
 209
 210 sub now () { my ($v); defined($v= time) or fail("get time"); return $v; }
 211 if ($keepalive) { $nextsendka= now(); }
 212
 213 for (;;) {
 214     if ($keepalive) {
 215         $now= now();
 216         $thistimeout= $nextsendka-$now;
 217         if ($thistimeout < 0) {
 218             defined(send L,"\300",0,$rs)
 219                 or warning("transmit keepalive error: $!");
 220             $nextsendka= $now+$keepalive;
 221             $thistimeout= $keepalive;
 222         }
 223     } else {
 224         $thistimeout= undef;
 225     }
 226     select($readfds=$wantreadfds,'','',$thistimeout);
 227     for (;;) {
 228         if (!defined($r= sysread(UR,$upbuf,$mtu*2+3,length($upbuf)))) {
 229             $! == EAGAIN || warning("tunnel endpoint read error: $!");
 230             last;
 231         }
 232         if (!$r) {
 233             quit "tunnel endpoint closed by system";
 234         }
 235         while (($p= index($upbuf,"\300")) >= 0) {
 236             if ($p && !defined(send L,substr($upbuf,0,$p),0,$rs)) {
 237                 warning("transmit error: $!");
 238             } else {
 239                 if (!$upyet) {
 240                     $upyet= 1;
 241                     debug($downyet ? "tunnel open at this end" : "transmitting");
 242                 }
 243                 if ($keepalive) { $nextsendka= now()+$keepalive; }
 244             }
 245             $upbuf= substr($upbuf,$p+1);
 246         }
 247     }
 248     while (defined($rs_from= recv L,$downbuf,$mtu*2+3,0)) {
 249         $rsp_from= show_addr_port($rs_from);
 250         if ($rsp_from ne $rsp) {
 251             warning("got packet from incorrect peer $rsp_from");
 252             next;
 253         }
 254         $downbuf= "\300".$downbuf."\300";
 255         if (!defined($r= syswrite(DW,$downbuf,length $downbuf))) {
 256             warning("tunnel endpoint write error: $!");
 257         } elsif ($r != length $downbuf) {
 258             warning("tunnel endpoint wrong write length");
 259         } else {
 260             if (!$downyet) {
 261                 $downyet= 1;
 262                 debug($upyet ? "tunnel open at this end" : "receiving");
 263             }
 264             alarm($timeout) if $timeout;
 265         }
 266     }
 267     if ($! == ECONNREFUSED) { quit("tunnel closed at remote end"); }
 268     $! == EAGAIN || warning("receive error: $!");
 269 }