发送404状态但浏览器在客户端显示500错误

Question

我试图根据IF条件发送http 404状态代码.但是,在客户端我看到http 500错误.在我的apach2错误日志中,我看到格式错误的标题.看了很多次我的代码,我无法弄清楚出了什么问题!任何人都可以建议我如何向客户发送404消息？

以下是我的perl代码:

#!/usr/bin/perl

use CGI qw(:standard);
use strict;
use warnings;
use Carp;
use File::Copy qw( copy );
use File::Spec::Functions qw( catfile );
use POSIX qw(strftime);
use Time::Local;
use HTTP::Status qw(:constants :is status_message);
use Digest::MD5 qw(md5 md5_hex md5_base64);
use File::Basename;
use URI;



my $extfile = '/home/suresh/clientrequest.txt';
open(FH, ">>$extfile") or die "Cannot open file";
my $query = CGI->new;
my $stcode = status_message(200);
my $uri =$ENV{'REQUEST_URI'};
my $rdate =strftime("%a, %d %b %Y %H:%M:%S %Z", localtime());
print FH "Got Following Headers:\n";
print FH $ENV{'REQUEST_URI'}, "\n";
my $dir  = '/home/suresh/Assets/';
my $nffFile = fileparse ("$uri", qr/\.[^.]*/);
my $fullFname = $nffFile . ".nff";
my $path = catfile($dir, $fullFname);
print FH "fullname:", $fullFname, "\n";

#Search requested asset files
opendir(DIR, $dir);
my @files = readdir(DIR);
if (grep($_=~/$fullFname/,@files)){
print FH "Found the file: ", $fullFname, "\n";
open my $fh, '<:raw', $path;
print "$ENV{SERVER_PROTOCOL} 200 $stcode";
print $query->header(
        -'Date'=> $rdate,
        -'Content-Type'=>'application/octet-stream',
        -'Connection'=>'Keep-Alive',
        -'attachment'=>$path,
    );
binmode STDOUT, ':raw';

 copy $fh => \*STDOUT;
    close $fh
        or die "Cannot close '$path': $!";

}else {
        $stcode = status_message(404);
        print "$ENV{'SERVER_PROTOCOL'} 404 $stcode\n";
        print $query->header(
        -'Server'=>$ENV{'SERVER_SOFTWARE'},
        -'Content-type'=>'text/plain',
        );
        }
closedir(DIR);

Answer 1

你应该打印头第一,先天下之忧.否则,浏览器将不知道如何处理您发送给它的内容.而不是这个:

print "$ENV{SERVER_PROTOCOL} 200 $stcode";
print $query->header( ... );

做这个:

print $query->header( ... );
print "$ENV{SERVER_PROTOCOL} 200 $stcode";

此外,您可以使用CGI.pm指定HTTP状态代码:

print $query->header( -status => '404 Not Found' );

调试CGI应用程序的一个小提示:更改

use Carp;

至

use CGI::Carp qw(fatalsToBrowser);

这将直接在浏览器中显示致命错误,因此您无需在Web服务器日志中搜索.但是,千万不要离开fatalsToBrowser在生产代码启用选项,因为它可以揭示你的应用程序的内部工作给攻击者.