#!/usr/bin/perl -w
# sanada4.pl - Don Yang (uguu.org)
#
# 11/26/03


use Socket;

sub T
{
   print "$$: ", (scalar(localtime)), ": @_\n";
}

die "$0 <file> [port] [type]\n" unless( $#ARGV > -1 );
($n, $p, $t) = @ARGV;
die "$n is empty\n" unless( (-f $n) && ($s = -s $n) > 0 );
$p ||= 80;
$t ||= "application/octet-stream";
$e = "\r\n";
$h =
   "Server: Sanada-san$e" .
   "Accept-Ranges: bytes$e" .
   "Content-Type: $t$e" .
   "Connection: close$e$e";

$SIG{"CHLD"} = "IGNORE";
die "$!\n" unless(
   socket(S, PF_INET, SOCK_STREAM, getprotobyname("tcp")) &&
   bind(S, sockaddr_in($p, INADDR_ANY)) &&
   listen(S, 5) &&
   binmode(S));
$x = "";
vec($x, fileno(S), 1) = 1;
T("serving $n (type=$t, size=$s) on port $p");
while( select($o = $x, undef, undef, undef) )
{
   if( vec($o, fileno(S), 1) )
   {
      $j = accept(C, S);
      ($j, $i) = sockaddr_in($j);
      $i = inet_ntoa($i);
      if( fork )
      {
         close(C);
      }
      else
      {
         T("request from $i:$j");

         binmode(C);
         defined(recv(C, $x, 1024, 0)) || die $!;

         T("agent=$1") if( $x =~ /\s+user-agent:\s*([^\r\n]+)/i );
         T("referer=$1") if( $x =~ /\s+referer:\s*([^\r\n]+)/i );
         $j = $s - 1;
         ($i, $j) =
             ($x =~ /\s+range:\s*bytes=(\d+)-(\d+)/i) ? ($1, $2)
           : ($x =~ /\s+range:\s*bytes=(\d+)-/i) ? ($1, $j)
           : ($x =~ /\s+range:\s*bytes=-(\d+)/i) ? ($s - $1, $j)
           : (0, $j);

         $o =
         (
             ($i >= $s || $j >= $s || $j < $i)
           ?      "HTTP/1.1 416 Requested Range Not Satisfiable$e" .
                  "Content-Range: bytes */$s$e"
           : (
               ($i > 0 || $j < $s - 1)
                  ?  "HTTP/1.1 206 Partial Content$e" .
                     "Content-Range: bytes $i-$j/$s$e"
                  :  "HTTP/1.1 200 OK$e"
             ) . "Content-Length: " . ($j - $i + 1) . $e
         ) . $h;

         send(C, $o, 0) || die $!;
         if( ($o =~ /1\.1 20/) && ($x =~ /^GET /) )
         {
            open(D, "< $n");
            $j++;
            for(seek(D, $i, $t = 0); $i < $j; $i += $p)
            {
               if(($p = $j - $i) > 0x4000) {$p = 0x4000;}
               read(D, $o, $p);
               last unless defined(send(C, $o, 0));
               $t += $p;
            }
            close(D);
            if($i < $j) {$t = "~$t";}
            T("sent $t bytes");
         }
         shutdown(C, 2);
         close(C);
         exit(0);
      }
   }
}
die "$!\n";