| 1 | #! /bin/perl |
| 2 | |
| 3 | use Socket; |
| 4 | |
| 5 | # --- Read the network interface to steal --- |
| 6 | |
| 7 | $netif = shift; |
| 8 | |
| 9 | # --- Start a child if so requested --- |
| 10 | |
| 11 | if (@ARGV) { |
| 12 | socketpair(ONE, TOTHER, PF_UNIX, SOCK_STREAM, 0) |
| 13 | or die "socketpair: $!"; |
| 14 | $kid = fork(); |
| 15 | defined $kid or die "fork: $!"; |
| 16 | if ($kid) { |
| 17 | close ONE; |
| 18 | open STDIN, ">&TOTHER" or die "dup stdin: $!"; |
| 19 | open STDOUT, ">&TOTHER" or die "dup stdout: $!"; |
| 20 | close TOTHER; |
| 21 | exec @ARGV; |
| 22 | die "exec: $!"; |
| 23 | } |
| 24 | close TOTHER; |
| 25 | open STDIN, ">&ONE" or die "dup stdin: $!"; |
| 26 | open STDOUT, ">&ONE" or die "dup stdout: $!"; |
| 27 | close ONE; |
| 28 | } |
| 29 | |
| 30 | # --- Now start work on this --- |
| 31 | |
| 32 | open NETIF, "+> $netif" or die "open($netif): $!"; |
| 33 | |
| 34 | for (;;) { |
| 35 | $rfd = ''; |
| 36 | vec($rfd, fileno(STDIN), 1) = 1; |
| 37 | vec($rfd, fileno(NETIF), 1) = 1; |
| 38 | select($rfd, undef, undef, undef) or die "select: $!"; |
| 39 | |
| 40 | if (vec($rfd, fileno(NETIF), 1)) { |
| 41 | sysread(NETIF, $pkt, 65536); |
| 42 | $pkt = pack("n", length($pkt)) . $pkt; |
| 43 | syswrite(STDOUT, $pkt, length($pkt)); |
| 44 | } |
| 45 | if (vec($rfd, fileno(STDIN), 1)) { |
| 46 | sysread(STDIN, $clen, 2) or die "tunnel has vanished: $!"; |
| 47 | $len = unpack("n", $clen); |
| 48 | sysread(STDIN, $pkt, $len); |
| 49 | syswrite(NETIF, $pkt, length($pkt)); |
| 50 | } |
| 51 | } |