PERLFAQ9 7

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PERLFAQ9

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DESCRIPTION æè¿°
AUTHOR AND COPYRIGHT
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NAME

perlfaq9 - ç½ç» (2003/01/31 17:36:57 )

DESCRIPTION æè¿°

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What is the correct form of response from a CGI script?

(Alan Flavell <flavell+www@a5.ph.gla.ac.uk> answers...)

The Common Gateway Interface ( CGI ) specifies a software interface between a program (" CGI script") and a web server ( HTTPD ). It is not specific to Perl, and has its own FAQs and tutorials, and usenet group, comp.infosystems.www.authoring.cgi

The original CGI specification is at: http://hoohoo.ncsa.uiuc.edu/cgi/

Current best-practice RFC draft at: http://CGI-Spec.Golux.Com/

Other relevant documentation listed in: http://www.perl.org/CGI_MetaFAQ.html

These Perl FAQs very selectively cover some CGI issues. However, Perl programmers are strongly advised to use the CGI .pm module, to take care of the details for them.

The similarity between CGI response headers (defined in the CGI specification) and HTTP response headers (defined in the HTTP specification, RFC2616 ) is intentional, but can sometimes be confusing.

The CGI specification defines two kinds of script: the "Parsed Header" script, and the "Non Parsed Header" ( NPH ) script. Check your server documentation to see what it supports. "Parsed Header" scripts are simpler in various respects. The CGI specification allows any of the usual newline representations in the CGI response (it’s the server’s job to create an accurate HTTP response based on it). So "\n" written in text mode is technically correct, and recommended. NPH scripts are more tricky: they must put out a complete and accurate set of HTTP transaction response headers; the HTTP specification calls for records to be terminated with carriage-return and line-feed, i.e ASCII \015\012 written in binary mode.

Using CGI .pm gives excellent platform independence, including EBCDIC systems. CGI .pm selects an appropriate newline representation ($CGI::CRLF) and sets binmode as appropriate.

å¯è½æå¾å¤äºéäºãå¯ä»¥ä»ç»éè¯» "Troubleshooting Perl CGI scripts" guide, ä½ç½®æ¯

http://www.perl.org/troubleshooting_CGI.html

å ä¸ªå®ç¨ç FAQï¼ç¸å³ææ¡£åæ¥éåå¯¼åå¨ CGI Meta FAQ ä¸ï¼

http://www.perl.org/CGI_MetaFAQ.html

å¦ä½ä» CGI ç¨åºä¸å¾å°å¥½ä¸ç¹çéè¯¯æç¤ºï¼

Use the CGI::Carp module. It replaces "warn" and "die", plus the normal Carp modules "carp", "croak", and "confess" functions with more verbose and safer versions. It still sends them to the normal server error log.

use CGI::Carp;
warn "This is a complaint";
die "But this one is serious";

The following use of CGI::Carp also redirects errors to a file of your choice, placed in a BEGIN block to catch compile-time warnings as well:

BEGIN {
use CGI::Carp qw(carpout);
open(LOG, ">>/var/local/cgi-logs/mycgi-log")
or die "Unable to append to mycgi-log: $!\n";
carpout(*LOG);
}

You can even arrange for fatal errors to go back to the client browser, which is nice for your own debugging, but might confuse the end user.

use CGI::Carp qw(fatalsToBrowser);
die "Bad error here";

Even if the error happens before you get the HTTP header out, the module will try to take care of this to avoid the dreaded server 500 errors. Normal warnings still go out to the server error log (or wherever you’ve sent them with "carpout") with the application name and date stamp prepended.

å¦ä½å°åç¬¦ä¸²ä¸ç HTML å é¤ï¼

ä»¥ä¸è¿ä¸ªãç®éãçæ¹æ³å¯¹å¤§å¤æ°çæ¡£æ¡é½ææï¼

#!/usr/bin/perl -p0777
s/<(?:[ˆ>’"]*⎪([’"]).*?\1)*>//gs

å¦ææ¨æ³è¦æ´å®æ´çè§£æ³ï¼è¯·çåé¨æ²ç striphtml ç¨å¼ï¼ http://www.cpan.org/authors/Tom_Christiansen/scripts/striphtml.gz .

Here are some tricky cases that you should think about when picking a solution:

<# Just data #>

<![INCLUDE CDATA [ >>>>>>>>>>>> ]]>

If HTML comments include other tags, those solutions would also break on text like this:

å¦ä½èå URL?

å¯ä»¥ç®åå°ä» HTML ä¸å¾å°ææç§ç±»ç URLï¼åªè¦ä½¿ç¨ "HTML::SimpleLinkExtor" æ¨¡åï¼å®å¯ä»¥å¤çéï¼å¾åï¼å¯¹è±¡ï¼æ¡¢ï¼å¶ä»åå« URL çæ ç- ¾ãå¦æéè¦æ´å¤æçä¸è¥¿ï¼å¯ä»¥åå»º "HTML::LinkExtor" çåç±»æä½¿ç¨ "HTML::Parser". ä½ çè³å¯ä»¥ç¨ "HTML::SimpleLinkExtor" ä½ä¸ºèä¾ï¼æ¥ä¹¦åéåä½ ç¹æ®éè¦çç¨åºã

You can use URI::Find to extract URLs from an arbitrary text document.

Less complete solutions involving regular expressions can save you a lot of processing time if you know that the input is simple. One solution from Tom Christiansen runs 100 times faster than most module based approaches but only extracts URLs from anchors where the first attribute is HREF and there are no other attributes.

#!/usr/bin/perl -n00
# qxurl - tchrist@perl.com
print "$2\n" while m{
< \s*
A \s+ HREF \s* = \s* (["’]) (.*?) \1
\s* >
}gsix;

In this case, download means to use the file upload feature of HTML forms. You allow the web surfer to specify a file to send to your web server. To you it looks like a download, and to the user it looks like an upload. No matter what you call it, you do it with what’s known as multipart/form-data encoding. The CGI .pm module (which comes with Perl as part of the Standard Library) supports this in the start_multipart_form() method, which isn’t the same as the startform() method.

See the section in the CGI .pm documentation on file uploads for code examples and details.

å¦ä½å¨ HTML æ·»å ä¸ä¸ªå¼¹åºèå?

å¦ä½è·å HTML æä»¶?

$html_code = ‘lynx -source $url‘;
$text_data = ‘lynx -dump $url‘;

# simplest version
use LWP::Simple;
$content = get($URL);

# or print HTML from a URL
use LWP::Simple;
getprint "http://www.linpro.no/lwp/";

# or print ASCII from HTML from a URL
# also need HTML-Tree package from CPAN
use LWP::Simple;
use HTML::Parser;
use HTML::FormatText;
my ($html, $ascii);
$html = get("http://www.perl.com/");
defined $html
or die "Can’t fetch HTML from http://www.perl.com/";
$ascii = HTML::FormatText->new->format(parse_html($html));
print $ascii;

å¦ä½æ ¹æ®æäº¤çåå®¹èªå¨çæä¸ä¸ª HTML ?

If you’re submitting values using the GET method, create a URL and encode the form using the "query_form" method:

use LWP::Simple;
use URI::URL;

my $url = url(’http://www.perl.com/cgi-bin/cpan_mod’);
$url->query_form(module => ’DB_File’, readme => 1);
$content = get($url);

If you’re using the POST method, create your own user agent and encode the content appropriately.

use HTTP::Request::Common qw(POST);
use LWP::UserAgent;

$ua = LWP::UserAgent->new();
my $req = POST ’http://www.perl.com/cgi-bin/cpan_mod’,
[ module => ’DB_File’, readme => 1 ];
$content = $ua->request($req)->as_string;

å¦ä½è§£ç æåå»º web ä¸ç %-encoding?

If you are writing a CGI script, you should be using the CGI .pm module that comes with perl, or some other equivalent module. The CGI module automatically decodes queries for you, and provides an escape() function to handle encoding.

The best source of detailed information on URI encoding is RFC 2396. Basically, the following substitutions do it:

s/([ˆ\w()’*˜!.-])/sprintf ’%%%02x’, ord $1/eg; # encode

s/%([A-Fa-f\d]{2})/chr hex $1/eg; # decode

However, you should only apply them to individual URI components, not the entire URI , otherwise you’ll lose information and generally mess things up. If that didn’t explain it, don’t worry. Just go read section 2 of the RFC , it’s probably the best explanation there is.

RFC 2396 also contains a lot of other useful information, including a regexp for breaking any arbitrary URI into components (Appendix B).

å¦ä½éå®åå°å¶ä»é¡µé¢ï¼

Specify the complete URL of the destination (even if it is on the same server). This is one of the two different kinds of CGI "Location:" responses which are defined in the CGI specification for a Parsed Headers script. The other kind (an absolute URLpath) is resolved internally to the server without any HTTP redirection. The CGI specifications do not allow relative URLs in either case.

Use of CGI .pm is strongly recommended. This example shows redirection with a complete URL . This redirection is handled by the web browser.

use CGI qw/:standard/;

my $url = ’http://www.cpan.org/’;
print redirect($url);

This example shows a redirection with an absolute URLpath. This redirection is handled by the local web server.

my $url = ’/CPAN/index.html’;
print redirect($url);

But if coded directly, it could be as follows (the final "\n" is shown separately, for clarity), using either a complete URL or an absolute URLpath.

print "Location: $url\n"; # CGI response header
print "\n"; # end of headers

å¦ä½ä¸ºæçç½é¡µå ä¸å¯ç ï¼

å¦ä½ç¨ Perl ä¿®æ¹æç .htpasswd å .htgroup æä»¶?

HTTPD::UserAdmin å HTTPD::GroupAdmin ç- æ¨¡ç»ä¸ºè¿äºæ¡£æ¡æä¾äºç»ä¸çç©ä»¶å¯¼åä»é¢ï¼å°½ç®¡è¿äºæ¡£æ¡å¯è½ä»¥åç§ä¸åçæ¼å¼å¨å- ãè¿äºèµæåºå¯è½æ¯çº¯æåæ ¼å¼ã dbmãBerkeley DBæä»»ä½ DBIç¸å®¹çèµæåºé©±å¨ç¨å¼ (drivers)ã HTTPD::UserAdminæ¯æ´‘Basic’ å ‘Digest’è¿ä¸¤ä¸ªè®¤è¯æ¨¡å¼æç¨çæ¡£æ¡ãä»¥ä¸æ¯ ä¸ä¾ï¼

use HTTPD::UserAdmin ();
HTTPD::UserAdmin
->new(DB => "/foo/.htpasswd")
->add($username => $password);

éè¯» CGI Meta FAQ ååºçå®å¨ç´¢å¼

http://www.perl.org/CGI_MetaFAQ.html

å¦ä½è§£éä¸ä¸ªé®ä»¶å¤´ï¼

$/ = ’’;
$header = <MSG>;
$header =˜ s/\n\s+/ /g; # å°å»¶ç»è¡åå¹¶æåè¡
%head = ( UNIX_FROM_LINE, split /ˆ([-\w]+):\s*/m, $header );

å¦ä½è§£ç ä¸ä¸ª CGI è¡¨åï¼

ä½ å¤§æ¦é½çè¿ä¸å¤§å ä» STDIN è¯»åä¸ $ENV{CONTENT_LENGTH} é¿åº¦ç¸åçå- èï¼æèè·å $ENV{QUERY_STRING} æ¥è§£ç GETãè¿äºç¨åºé½éå¸¸ç³ç³ãä»ä»¬ä»å¨æäºæ¶åå·¥ä½ãä»ä»¬éå¸¸ä¸æ£æ¥ read() çè¿åå¼ï¼è¿æ¯ä¸»è¦çéè¯¯ãä»ä»¬ä¸å¤ç HEAD è¯·æ±ãä»ä»¬ä¸å¤çæä»¶ä¸è½½æ¶çå¤æåè¡¨åãThey don’t deal with GET/POST combinations where query fields are in more than one place. They don’t deal with keywords in the query string.

In short, they’re bad hacks. Resist them at all costs. Please do not be tempted to reinvent the wheel. Instead, use the CGI .pm or CGI_Lite.pm (available from CPAN ), or if you’re trapped in the module-free land of perl1 .. perl4, you might look into cgi-lib.pl (available from http://cgi-lib.stanford.edu/cgi-lib/ ).

Make sure you know whether to use a GET or a POST in your form. GETs should only be used for something that doesn’t update the server. Otherwise you can get mangled databases and repeated feedback mail messages. The fancy word for this is ‘‘idempotency’’. This simply means that there should be no difference between making a GET request for a particular URL once or multiple times. This is because the HTTP protocol definition says that a GET request may be cached by the browser, or server, or an intervening proxy. POST requests cannot be cached, because each request is independent and matters. Typically, POST requests change or depend on state on the server (query or update a database, send mail, or purchase a computer).

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You can use the Email::Valid or RFC::RFC822::Address which check the format of the address, although they cannot actually tell you if it is a deliverable address (i.e. that mail to the address will not bounce). Modules like Mail::CheckUser and Mail::EXPN try to interact with the domain name system or particular mail servers to learn even more, but their methods do not work everywhere---especially for security conscious administrators.

Our best advice for verifying a person’s mail address is to have them enter their address twice, just as you normally do to change a password. This usually weeds out typos. If both versions match, send mail to that address with a personal message that looks somewhat like:

Dear someuser@host.com,

Please confirm the mail address you gave us Wed May 6 09:38:41
MDT 1998 by replying to this message. Include the string
"Rumpelstiltskin" in that reply, but spelled in reverse; that is,
start with "Nik...". Once this is done, your confirmed address will
be entered into our records.

If you get the message back and they’ve followed your directions, you can be reasonably assured that it’s real.

A related strategy that’s less open to forgery is to give them a PIN (personal ID number). Record the address and PIN (best that it be a random one) for later processing. In the mail you send, ask them to include the PIN in their reply. But if it bounces, or the message is included via a ‘‘vacation’’ script, it’ll be there anyway. So it’s best to ask them to mail back a slight alteration of the PIN , such as with the characters reversed, one added or subtracted to each digit, etc.

å¦ä½è§£ç ä¸ä¸ª MIME/BASE64 åç¬¦ä¸²?

use MIME::Base64;
$decoded = decode_base64($encoded);

The MIME-Tools package (available from CPAN ) supports extraction with decoding of BASE64 encoded attachments and content directly from email messages.

tr#A-Za-z0-9+/##cd; # remove non-base64 chars
tr#A-Za-z0-9+/# -_#; # convert to uuencoded format
$len = pack("c", 32 + 0.75*length); # compute length byte
print unpack("u", $len . $_); # uudecode and print

å¦ä½è¿åç¨æ·çé®ä»¶å°åï¼

On systems that support getpwuid, the $< variable, and the Sys::Hostname module (which is part of the standard perl distribution), you can probably try using something like this:

use Sys::Hostname;
$address = sprintf(’%s@%s’, scalar getpwuid($<), hostname);

Company policies on mail address can mean that this generates addresses that the company’s mail system will not accept, so you should ask for users’ mail addresses when this matters. Furthermore, not all systems on which Perl runs are so forthcoming with this information as is Unix.

The Mail::Util module from CPAN (part of the MailTools package) provides a mailaddress() function that tries to guess the mail address of the user. It makes a more intelligent guess than the code above, using information given when the module was installed, but it could still be incorrect. Again, the best way is often just to ask the user.

å¦ä½åé®ä»¶ï¼

Use the "sendmail" program directly:

open(SENDMAIL, "⎪/usr/lib/sendmail -oi -t -odq")
or die "Can’t fork for sendmail: $!\n";
print SENDMAIL <<"EOF";
From: User Originating Mail <me\@host>
To: Final Destination <you\@otherhost>
Subject: A relevant subject line

Body of the message goes here after the blank line
in as many lines as you like.
EOF
close(SENDMAIL) or warn "sendmail didn’t close nicely";

The -oi option prevents sendmail from interpreting a line consisting of a single dot as "end of message". The -t option says to use the headers to decide who to send the message to, and -odq says to put the message into the queue. This last option means your message won’t be immediately delivered, so leave it out if you want immediate delivery.

Alternate, less convenient approaches include calling mail (sometimes called mailx) directly or simply opening up port 25 have having an intimate conversation between just you and the remote SMTP daemon, probably sendmail.

Or you might be able use the CPAN module Mail::Mailer:

use Mail::Mailer;

$mailer = Mail::Mailer->new();
$mailer->open({ From => $from_address,
To => $to_address,
Subject => $subject,
})
or die "Can’t open: $!\n";
print $mailer $body;
$mailer->close();

The Mail::Internet module uses Net::SMTP which is less Unix-centric than Mail::Mailer, but less reliable. Avoid raw SMTP commands. There are many reasons to use a mail transport agent like sendmail. These include queuing, MX records, and security.

å¦ä½ä½¿ç¨ MIME æ¥ä¸ºé®ä»¶æ¶æ¯å¢å éä»¶ï¼

This answer is extracted directly from the MIME::Lite documentation. Create a multipart message (i.e., one with attachments).

use MIME::Lite;

### Create a new multipart message:
$msg = MIME::Lite->new(
From =>’me@myhost.com’,
To =>’you@yourhost.com’,
Cc =>’some@other.com, some@more.com’,
Subject =>’A message with 2 parts...’,
Type =>’multipart/mixed’
);

### Add parts (each "attach" has same arguments as "new"):
$msg->attach(Type =>’TEXT’,
Data =>"Here’s the GIF file you wanted"
);
$msg->attach(Type =>’image/gif’,
Path =>’aaa000123.gif’,
Filename =>’logo.gif’
);

$text = $msg->as_string;

MIME::Lite also includes a method for sending these things.

$msg->send;

This defaults to using sendmail but can be customized to use SMTP via Net::SMTP.

å¦ä½è¯»é®ä»¶ï¼

While you could use the Mail::Folder module from CPAN (part of the MailFolder package) or the Mail::Internet module from CPAN (part of the MailTools package), often a module is overkill. Here’s a mail sorter.

#!/usr/bin/perl

my(@msgs, @sub);
my $msgno = -1;
$/ = ’’; # paragraph reads
while (<>) {
if (/ˆFrom /m) {
/ˆSubject:\s*(?:Re:\s*)*(.*)/mi;
$sub[++$msgno] = lc($1) ⎪⎪ ’’;
}
$msgs[$msgno] .= $_;
}
for my $i (sort { $sub[$a] cmp $sub[$b] ⎪⎪ $a <=> $b } (0 .. $#msgs)) {
print $msgs[$i];
}

Or more succinctly,

#!/usr/bin/perl -n00
# bysub2 - awkish sort-by-subject
BEGIN { $msgno = -1 }
$sub[++$msgno] = (/ˆSubject:\s*(?:Re:\s*)*(.*)/mi)[0] if /ˆFrom/m;
$msg[$msgno] .= $_;
END { print @msg[ sort { $sub[$a] cmp $sub[$b] ⎪⎪ $a <=> $b } (0 .. $#msg) ] }

å¦ä½æ¾å°æçä¸»æºå/åå/IP å°åï¼

use Socket;
use Sys::Hostname;
my $host = hostname();
my $addr = inet_ntoa(scalar gethostbyname($host ⎪⎪ ’localhost’));

å¦ä½è·åä¸ç¯æ°é»æç« ææ´»å¨çæ°é»ç»ï¼

perl -MNews::NNTPClient
-e ’print News::NNTPClient->new->list("newsgroups")’

å¦ä½è·å/ä¸ä¼ ä¸ä¸ª FTP æä»¶?

å¦ä½è¿è¡è¿ç¨è¿ç¨è°ç¨ RPC ?

æ¨¡å DCE::RPC æ£å¨å¼åä¸ (ä½æ¯è¿ä¸å¯ç¨)ï¼å°æä¸º DCE-Perl å (å¯ä»¥ä» CPAN ä¸è½½) çä¸é¨åãrpcgen å¥ä»¶ï¼å¯ä»¥ä» CPAN/authors/id/JAKE/ æ¾å°ï¼æ¯ä¸ä¸ª RPC åæ ¹çæå¨ï¼åå«ä¸ä¸ª RPC::ONC æ¨¡åã

AUTHOR AND COPYRIGHT

This documentation is free; you can redistribute it and/or modify it under the same terms as Perl itself.

Irrespective of its distribution, all code examples in this file are hereby placed into the public domain. You are permitted and encouraged to use this code in your own programs for fun or for profit as you see fit. A simple comment in the code giving credit would be courteous but is not required.

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æ¬é¡µé¢ä¸æçç±ä¸æ man æåé¡µè®¡åæä¾ã
ä¸æ man æåé¡µè®¡åï¼https://github.com/man-pages-zh/manpages-zh

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