一个支持HTTP续传下载的PERL程序

答案：#!/usr/bin/perl 
use IO::Socket; 

if ($#ARGV <= 0) { 
  print STDERR "usage: getright <URL> <FILENAME>\n\n"; 
  print STDERR "     <URL>: eg. http://www.server.dom:port/path/file.ext\n"; 
  print STDERR "<FILENAME>: eg. filename.ext\n"; 
  exit(0); 
} else { 
  open(FILE, "+>>".$ARGV[1]) or die "Cannot open $ARGV[1] for append: $!"; 
  ($length = sysseek(FILE,0,2)) =~ s!.*([0-9]+).*!$1!g; 
  print STDERR "Attempting to resume $ARGV[1] from byte: $length\n"; 
} 

if ($ARGV[0] =~ m!^ (?:http://)? (.*?) (?:\:([0-9]+))? (/.*)$!x) 
  { ($server,$port,$path) = ($1, $2 || 80, $3); } 

print "[$server] [$port] [$path]\n"; 

$socket = IO::Socket::INET->new(PeerAddr => $server, 
                                PeerPort => $port, 
                                Proto    => 'tcp', 
                                Type     => SOCK_STREAM) or die "Cannot connect: $!"; 

print $socket "GET $path HTTP/1.0\n"; 
print $socket "Host: $server\n"; 
print $socket "Range: bytes=$length-\n"; 
print $socket "Connection: close\n\n"; 

if (!(($reply = <$socket>) =~ /HTTP\/1.[01] 206 Partial Content/)) { 
  $reply =~ s!(.*)\r\n!$1!; 
  print STDERR "Failed [$reply]\n"; 
  print STDERR "Invalid URL/Unrecognized Reply/Resume Not Supported.\n"; 
  close($socket); exit(0); 
} else { 
  print STDERR "Received valid HTTP reply.\n"; 
} 

while (($mime = <$socket>) =~ /\w+: /) { 
  if ($mime =~ /Content\-Range\:\sbytes\s([0-9]+)\-([0-9]+)\/([0-9]+)/) 
    { ($start,$finish,$filesize) = ($1, $2, $3); } 
  if ($mime =~ /Content\-Length\:\s([0-9]+)/) { $total = $1; } 
} 

print STDERR "Receiving data: "; 
while ($data = <$socket>) { 
  $recieved += length($data); 
  $percentage= int((($start+$recieved) / $filesize) * 100); 
  print STDERR $percentage."%"."\b"x(length($percentage)+1); 
  print FILE $data; 
} 

print STDERR "100%\n"; 
close(FILE); 
close($socket); 

# Example HTTP return header: 
# 
#          HTTP/1.1 206 Partial content 
#          Date: Wed, 15 Nov 1995 06:25:24 GMT 
#          Last-modified: Wed, 15 Nov 1995 04:58:08 GMT 
#          Content-Range: bytes 21010-47021/47022 
#          Content-Length: 26012 
#          Content-Type: image/gif 

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