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1 | =head1 NAME |
2 | |
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3 | perlfaq9 - Networking ($Revision: 1.26 $, $Date: 2005/11/21 17:43:13 $) |
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4 | |
5 | =head1 DESCRIPTION |
6 | |
7 | This section deals with questions related to networking, the internet, |
8 | and a few on the web. |
9 | |
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10 | =head2 What is the correct form of response from a CGI script? |
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11 | |
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12 | (Alan Flavell <flavell+www@a5.ph.gla.ac.uk> answers...) |
13 | |
197aec24 |
14 | The Common Gateway Interface (CGI) specifies a software interface between |
15 | a program ("CGI script") and a web server (HTTPD). It is not specific |
16 | to Perl, and has its own FAQs and tutorials, and usenet group, |
17 | comp.infosystems.www.authoring.cgi |
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18 | |
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19 | The CGI specification is outlined in an informational RFC: |
20 | http://www.ietf.org/rfc/rfc3875 |
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21 | |
22 | Other relevant documentation listed in: http://www.perl.org/CGI_MetaFAQ.html |
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23 | |
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24 | These Perl FAQs very selectively cover some CGI issues. However, Perl |
24f1ba9b |
25 | programmers are strongly advised to use the CGI.pm module, to take care |
197aec24 |
26 | of the details for them. |
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27 | |
24f1ba9b |
28 | The similarity between CGI response headers (defined in the CGI |
29 | specification) and HTTP response headers (defined in the HTTP |
30 | specification, RFC2616) is intentional, but can sometimes be confusing. |
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31 | |
24f1ba9b |
32 | The CGI specification defines two kinds of script: the "Parsed Header" |
33 | script, and the "Non Parsed Header" (NPH) script. Check your server |
34 | documentation to see what it supports. "Parsed Header" scripts are |
35 | simpler in various respects. The CGI specification allows any of the |
36 | usual newline representations in the CGI response (it's the server's |
37 | job to create an accurate HTTP response based on it). So "\n" written in |
38 | text mode is technically correct, and recommended. NPH scripts are more |
39 | tricky: they must put out a complete and accurate set of HTTP |
40 | transaction response headers; the HTTP specification calls for records |
41 | to be terminated with carriage-return and line-feed, i.e ASCII \015\012 |
42 | written in binary mode. |
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43 | |
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44 | Using CGI.pm gives excellent platform independence, including EBCDIC |
45 | systems. CGI.pm selects an appropriate newline representation |
46 | ($CGI::CRLF) and sets binmode as appropriate. |
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47 | |
24f1ba9b |
48 | =head2 My CGI script runs from the command line but not the browser. (500 Server Error) |
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49 | |
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50 | Several things could be wrong. You can go through the "Troubleshooting |
51 | Perl CGI scripts" guide at |
52 | |
53 | http://www.perl.org/troubleshooting_CGI.html |
54 | |
197aec24 |
55 | If, after that, you can demonstrate that you've read the FAQs and that |
24f1ba9b |
56 | your problem isn't something simple that can be easily answered, you'll |
57 | probably receive a courteous and useful reply to your question if you |
58 | post it on comp.infosystems.www.authoring.cgi (if it's something to do |
59 | with HTTP or the CGI protocols). Questions that appear to be Perl |
60 | questions but are really CGI ones that are posted to comp.lang.perl.misc |
61 | are not so well received. |
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62 | |
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63 | The useful FAQs, related documents, and troubleshooting guides are |
24f1ba9b |
64 | listed in the CGI Meta FAQ: |
65 | |
66 | http://www.perl.org/CGI_MetaFAQ.html |
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67 | |
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68 | |
69 | =head2 How can I get better error messages from a CGI program? |
70 | |
71 | Use the CGI::Carp module. It replaces C<warn> and C<die>, plus the |
72 | normal Carp modules C<carp>, C<croak>, and C<confess> functions with |
73 | more verbose and safer versions. It still sends them to the normal |
74 | server error log. |
75 | |
76 | use CGI::Carp; |
77 | warn "This is a complaint"; |
78 | die "But this one is serious"; |
79 | |
80 | The following use of CGI::Carp also redirects errors to a file of your choice, |
81 | placed in a BEGIN block to catch compile-time warnings as well: |
82 | |
83 | BEGIN { |
84 | use CGI::Carp qw(carpout); |
85 | open(LOG, ">>/var/local/cgi-logs/mycgi-log") |
86 | or die "Unable to append to mycgi-log: $!\n"; |
87 | carpout(*LOG); |
88 | } |
89 | |
90 | You can even arrange for fatal errors to go back to the client browser, |
91 | which is nice for your own debugging, but might confuse the end user. |
92 | |
93 | use CGI::Carp qw(fatalsToBrowser); |
94 | die "Bad error here"; |
95 | |
96 | Even if the error happens before you get the HTTP header out, the module |
97 | will try to take care of this to avoid the dreaded server 500 errors. |
98 | Normal warnings still go out to the server error log (or wherever |
99 | you've sent them with C<carpout>) with the application name and date |
100 | stamp prepended. |
101 | |
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102 | =head2 How do I remove HTML from a string? |
103 | |
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104 | The most correct way (albeit not the fastest) is to use HTML::Parser |
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105 | from CPAN. Another mostly correct |
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106 | way is to use HTML::FormatText which not only removes HTML but also |
107 | attempts to do a little simple formatting of the resulting plain text. |
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108 | |
109 | Many folks attempt a simple-minded regular expression approach, like |
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110 | C<< s/<.*?>//g >>, but that fails in many cases because the tags |
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111 | may continue over line breaks, they may contain quoted angle-brackets, |
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112 | or HTML comment may be present. Plus, folks forget to convert |
113 | entities--like C<<> for example. |
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114 | |
115 | Here's one "simple-minded" approach, that works for most files: |
116 | |
117 | #!/usr/bin/perl -p0777 |
118 | s/<(?:[^>'"]*|(['"]).*?\1)*>//gs |
119 | |
120 | If you want a more complete solution, see the 3-stage striphtml |
121 | program in |
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122 | http://www.cpan.org/authors/Tom_Christiansen/scripts/striphtml.gz |
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123 | . |
124 | |
c8db1d39 |
125 | Here are some tricky cases that you should think about when picking |
126 | a solution: |
127 | |
128 | <IMG SRC = "foo.gif" ALT = "A > B"> |
129 | |
d92eb7b0 |
130 | <IMG SRC = "foo.gif" |
c8db1d39 |
131 | ALT = "A > B"> |
132 | |
133 | <!-- <A comment> --> |
134 | |
135 | <script>if (a<b && a>c)</script> |
136 | |
137 | <# Just data #> |
138 | |
139 | <![INCLUDE CDATA [ >>>>>>>>>>>> ]]> |
140 | |
141 | If HTML comments include other tags, those solutions would also break |
142 | on text like this: |
143 | |
144 | <!-- This section commented out. |
145 | <B>You can't see me!</B> |
146 | --> |
147 | |
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148 | =head2 How do I extract URLs? |
149 | |
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150 | You can easily extract all sorts of URLs from HTML with |
151 | C<HTML::SimpleLinkExtor> which handles anchors, images, objects, |
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152 | frames, and many other tags that can contain a URL. If you need |
153 | anything more complex, you can create your own subclass of |
154 | C<HTML::LinkExtor> or C<HTML::Parser>. You might even use |
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155 | C<HTML::SimpleLinkExtor> as an example for something specifically |
156 | suited to your needs. |
157 | |
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158 | You can use URI::Find to extract URLs from an arbitrary text document. |
159 | |
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160 | Less complete solutions involving regular expressions can save |
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161 | you a lot of processing time if you know that the input is simple. One |
162 | solution from Tom Christiansen runs 100 times faster than most |
163 | module based approaches but only extracts URLs from anchors where the first |
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164 | attribute is HREF and there are no other attributes. |
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165 | |
166 | #!/usr/bin/perl -n00 |
167 | # qxurl - tchrist@perl.com |
168 | print "$2\n" while m{ |
169 | < \s* |
170 | A \s+ HREF \s* = \s* (["']) (.*?) \1 |
171 | \s* > |
172 | }gsix; |
173 | |
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174 | |
175 | =head2 How do I download a file from the user's machine? How do I open a file on another machine? |
176 | |
49d635f9 |
177 | In this case, download means to use the file upload feature of HTML |
178 | forms. You allow the web surfer to specify a file to send to your web |
179 | server. To you it looks like a download, and to the user it looks |
180 | like an upload. No matter what you call it, you do it with what's |
181 | known as B<multipart/form-data> encoding. The CGI.pm module (which |
182 | comes with Perl as part of the Standard Library) supports this in the |
183 | start_multipart_form() method, which isn't the same as the startform() |
184 | method. |
185 | |
186 | See the section in the CGI.pm documentation on file uploads for code |
187 | examples and details. |
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188 | |
189 | =head2 How do I make a pop-up menu in HTML? |
190 | |
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191 | Use the B<< <SELECT> >> and B<< <OPTION> >> tags. The CGI.pm |
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192 | module (available from CPAN) supports this widget, as well as many |
193 | others, including some that it cleverly synthesizes on its own. |
194 | |
195 | =head2 How do I fetch an HTML file? |
196 | |
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197 | One approach, if you have the lynx text-based HTML browser installed |
198 | on your system, is this: |
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199 | |
200 | $html_code = `lynx -source $url`; |
201 | $text_data = `lynx -dump $url`; |
202 | |
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203 | The libwww-perl (LWP) modules from CPAN provide a more powerful way |
204 | to do this. They don't require lynx, but like lynx, can still work |
205 | through proxies: |
46fc3d4c |
206 | |
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207 | # simplest version |
208 | use LWP::Simple; |
209 | $content = get($URL); |
210 | |
211 | # or print HTML from a URL |
46fc3d4c |
212 | use LWP::Simple; |
6cecdcac |
213 | getprint "http://www.linpro.no/lwp/"; |
46fc3d4c |
214 | |
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215 | # or print ASCII from HTML from a URL |
65acb1b1 |
216 | # also need HTML-Tree package from CPAN |
46fc3d4c |
217 | use LWP::Simple; |
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218 | use HTML::Parser; |
46fc3d4c |
219 | use HTML::FormatText; |
220 | my ($html, $ascii); |
221 | $html = get("http://www.perl.com/"); |
222 | defined $html |
223 | or die "Can't fetch HTML from http://www.perl.com/"; |
224 | $ascii = HTML::FormatText->new->format(parse_html($html)); |
225 | print $ascii; |
226 | |
c8db1d39 |
227 | =head2 How do I automate an HTML form submission? |
228 | |
7678cced |
229 | If you are doing something complex, such as moving through many pages |
230 | and forms or a web site, you can use C<WWW::Mechanize>. See its |
231 | documentation for all the details. |
232 | |
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233 | If you're submitting values using the GET method, create a URL and encode |
234 | the form using the C<query_form> method: |
235 | |
236 | use LWP::Simple; |
237 | use URI::URL; |
238 | |
239 | my $url = url('http://www.perl.com/cgi-bin/cpan_mod'); |
240 | $url->query_form(module => 'DB_File', readme => 1); |
241 | $content = get($url); |
242 | |
243 | If you're using the POST method, create your own user agent and encode |
244 | the content appropriately. |
245 | |
246 | use HTTP::Request::Common qw(POST); |
247 | use LWP::UserAgent; |
248 | |
249 | $ua = LWP::UserAgent->new(); |
250 | my $req = POST 'http://www.perl.com/cgi-bin/cpan_mod', |
251 | [ module => 'DB_File', readme => 1 ]; |
252 | $content = $ua->request($req)->as_string; |
253 | |
254 | =head2 How do I decode or create those %-encodings on the web? |
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255 | |
575cc754 |
256 | If you are writing a CGI script, you should be using the CGI.pm module |
257 | that comes with perl, or some other equivalent module. The CGI module |
258 | automatically decodes queries for you, and provides an escape() |
259 | function to handle encoding. |
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260 | |
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261 | The best source of detailed information on URI encoding is RFC 2396. |
262 | Basically, the following substitutions do it: |
263 | |
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264 | s/([^\w()'*~!.-])/sprintf '%%%02x', ord $1/eg; # encode |
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265 | |
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266 | s/%([A-Fa-f\d]{2})/chr hex $1/eg; # decode |
267 | s/%([[:xdigit:]]{2})/chr hex $1/eg; # same thing |
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268 | |
269 | However, you should only apply them to individual URI components, not |
270 | the entire URI, otherwise you'll lose information and generally mess |
271 | things up. If that didn't explain it, don't worry. Just go read |
272 | section 2 of the RFC, it's probably the best explanation there is. |
273 | |
274 | RFC 2396 also contains a lot of other useful information, including a |
275 | regexp for breaking any arbitrary URI into components (Appendix B). |
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276 | |
277 | =head2 How do I redirect to another page? |
278 | |
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279 | Specify the complete URL of the destination (even if it is on the same |
280 | server). This is one of the two different kinds of CGI "Location:" |
281 | responses which are defined in the CGI specification for a Parsed Headers |
282 | script. The other kind (an absolute URLpath) is resolved internally to |
283 | the server without any HTTP redirection. The CGI specifications do not |
284 | allow relative URLs in either case. |
285 | |
286 | Use of CGI.pm is strongly recommended. This example shows redirection |
287 | with a complete URL. This redirection is handled by the web browser. |
288 | |
289 | use CGI qw/:standard/; |
290 | |
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291 | my $url = 'http://www.cpan.org/'; |
24f1ba9b |
292 | print redirect($url); |
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293 | |
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294 | |
24f1ba9b |
295 | This example shows a redirection with an absolute URLpath. This |
296 | redirection is handled by the local web server. |
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297 | |
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298 | my $url = '/CPAN/index.html'; |
299 | print redirect($url); |
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300 | |
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301 | |
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302 | But if coded directly, it could be as follows (the final "\n" is |
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303 | shown separately, for clarity), using either a complete URL or |
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304 | an absolute URLpath. |
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305 | |
24f1ba9b |
306 | print "Location: $url\n"; # CGI response header |
307 | print "\n"; # end of headers |
d92eb7b0 |
308 | |
c8db1d39 |
309 | |
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310 | =head2 How do I put a password on my web pages? |
311 | |
49d635f9 |
312 | To enable authentication for your web server, you need to configure |
313 | your web server. The configuration is different for different sorts |
314 | of web servers---apache does it differently from iPlanet which does |
315 | it differently from IIS. Check your web server documentation for |
316 | the details for your particular server. |
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317 | |
318 | =head2 How do I edit my .htpasswd and .htgroup files with Perl? |
319 | |
320 | The HTTPD::UserAdmin and HTTPD::GroupAdmin modules provide a |
321 | consistent OO interface to these files, regardless of how they're |
426affbf |
322 | stored. Databases may be text, dbm, Berkeley DB or any database with |
323 | a DBI compatible driver. HTTPD::UserAdmin supports files used by the |
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324 | "Basic" and "Digest" authentication schemes. Here's an example: |
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325 | |
326 | use HTTPD::UserAdmin (); |
327 | HTTPD::UserAdmin |
328 | ->new(DB => "/foo/.htpasswd") |
329 | ->add($username => $password); |
330 | |
46fc3d4c |
331 | =head2 How do I make sure users can't enter values into a form that cause my CGI script to do bad things? |
332 | |
24f1ba9b |
333 | See the security references listed in the CGI Meta FAQ |
46fc3d4c |
334 | |
24f1ba9b |
335 | http://www.perl.org/CGI_MetaFAQ.html |
46fc3d4c |
336 | |
5a964f20 |
337 | =head2 How do I parse a mail header? |
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338 | |
339 | For a quick-and-dirty solution, try this solution derived |
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340 | from L<perlfunc/split>: |
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341 | |
342 | $/ = ''; |
343 | $header = <MSG>; |
344 | $header =~ s/\n\s+/ /g; # merge continuation lines |
345 | %head = ( UNIX_FROM_LINE, split /^([-\w]+):\s*/m, $header ); |
346 | |
347 | That solution doesn't do well if, for example, you're trying to |
348 | maintain all the Received lines. A more complete approach is to use |
349 | the Mail::Header module from CPAN (part of the MailTools package). |
350 | |
351 | =head2 How do I decode a CGI form? |
352 | |
7678cced |
353 | (contributed by brian d foy) |
354 | |
355 | Use the CGI.pm module that comes with Perl. It's quick, |
356 | it's easy, and it actually does quite a bit of work to |
357 | ensure things happen correctly. It handles GET, POST, and |
358 | HEAD requests, multipart forms, multivalued fields, query |
359 | string and message body combinations, and many other things |
360 | you probably don't want to think about. |
361 | |
362 | It doesn't get much easier: the CGI module automatically |
363 | parses the input and makes each value available through the |
364 | C<param()> function. |
365 | |
366 | use CGI qw(:standard); |
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367 | |
9e72e4c6 |
368 | my $total = param( 'price' ) + param( 'shipping' ); |
6670e5e7 |
369 | |
9e72e4c6 |
370 | my @items = param( 'item' ); # multiple values, same field name |
6670e5e7 |
371 | |
7678cced |
372 | If you want an object-oriented approach, CGI.pm can do that too. |
373 | |
374 | use CGI; |
6670e5e7 |
375 | |
7678cced |
376 | my $cgi = CGI->new(); |
6670e5e7 |
377 | |
9e72e4c6 |
378 | my $total = $cgi->param( 'price' ) + $cgi->param( 'shipping' ); |
6670e5e7 |
379 | |
9e72e4c6 |
380 | my @items = $cgi->param( 'item' ); |
7678cced |
381 | |
382 | You might also try CGI::Minimal which is a lightweight version |
383 | of the same thing. Other CGI::* modules on CPAN might work better |
384 | for you, too. |
385 | |
386 | Many people try to write their own decoder (or copy one from |
387 | another program) and then run into one of the many "gotchas" |
388 | of the task. It's much easier and less hassle to use CGI.pm. |
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389 | |
5a964f20 |
390 | =head2 How do I check a valid mail address? |
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391 | |
c8db1d39 |
392 | You can't, at least, not in real time. Bummer, eh? |
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393 | |
c8db1d39 |
394 | Without sending mail to the address and seeing whether there's a human |
c98c5709 |
395 | on the other end to answer you, you cannot determine whether a mail |
c8db1d39 |
396 | address is valid. Even if you apply the mail header standard, you |
397 | can have problems, because there are deliverable addresses that aren't |
398 | RFC-822 (the mail header standard) compliant, and addresses that aren't |
399 | deliverable which are compliant. |
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400 | |
49d635f9 |
401 | You can use the Email::Valid or RFC::RFC822::Address which check |
402 | the format of the address, although they cannot actually tell you |
403 | if it is a deliverable address (i.e. that mail to the address |
404 | will not bounce). Modules like Mail::CheckUser and Mail::EXPN |
405 | try to interact with the domain name system or particular |
406 | mail servers to learn even more, but their methods do not |
407 | work everywhere---especially for security conscious administrators. |
408 | |
c8db1d39 |
409 | Many are tempted to try to eliminate many frequently-invalid |
d92eb7b0 |
410 | mail addresses with a simple regex, such as |
b8c8cfe2 |
411 | C</^[\w.-]+\@(?:[\w-]+\.)+\w+$/>. It's a very bad idea. However, |
c8db1d39 |
412 | this also throws out many valid ones, and says nothing about |
b8c8cfe2 |
413 | potential deliverability, so it is not suggested. Instead, see |
1577cd80 |
414 | http://www.cpan.org/authors/Tom_Christiansen/scripts/ckaddr.gz , |
68dc0745 |
415 | which actually checks against the full RFC spec (except for nested |
5a964f20 |
416 | comments), looks for addresses you may not wish to accept mail to |
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417 | (say, Bill Clinton or your postmaster), and then makes sure that the |
c8db1d39 |
418 | hostname given can be looked up in the DNS MX records. It's not fast, |
419 | but it works for what it tries to do. |
420 | |
421 | Our best advice for verifying a person's mail address is to have them |
422 | enter their address twice, just as you normally do to change a password. |
423 | This usually weeds out typos. If both versions match, send |
424 | mail to that address with a personal message that looks somewhat like: |
425 | |
426 | Dear someuser@host.com, |
427 | |
428 | Please confirm the mail address you gave us Wed May 6 09:38:41 |
429 | MDT 1998 by replying to this message. Include the string |
430 | "Rumpelstiltskin" in that reply, but spelled in reverse; that is, |
431 | start with "Nik...". Once this is done, your confirmed address will |
432 | be entered into our records. |
433 | |
434 | If you get the message back and they've followed your directions, |
435 | you can be reasonably assured that it's real. |
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436 | |
c8db1d39 |
437 | A related strategy that's less open to forgery is to give them a PIN |
438 | (personal ID number). Record the address and PIN (best that it be a |
439 | random one) for later processing. In the mail you send, ask them to |
440 | include the PIN in their reply. But if it bounces, or the message is |
b432a672 |
441 | included via a "vacation" script, it'll be there anyway. So it's |
c8db1d39 |
442 | best to ask them to mail back a slight alteration of the PIN, such as |
443 | with the characters reversed, one added or subtracted to each digit, etc. |
46fc3d4c |
444 | |
68dc0745 |
445 | =head2 How do I decode a MIME/BASE64 string? |
446 | |
6a0af2f1 |
447 | The MIME-Base64 package (available from CPAN) handles this as well as |
448 | the MIME/QP encoding. Decoding BASE64 becomes as simple as: |
68dc0745 |
449 | |
6a0af2f1 |
450 | use MIME::Base64; |
68dc0745 |
451 | $decoded = decode_base64($encoded); |
452 | |
26d9b02f |
453 | The MIME-Tools package (available from CPAN) supports extraction with |
6a0af2f1 |
454 | decoding of BASE64 encoded attachments and content directly from email |
455 | messages. |
456 | |
457 | If the string to decode is short (less than 84 bytes long) |
458 | a more direct approach is to use the unpack() function's "u" |
68dc0745 |
459 | format after minor transliterations: |
460 | |
461 | tr#A-Za-z0-9+/##cd; # remove non-base64 chars |
462 | tr#A-Za-z0-9+/# -_#; # convert to uuencoded format |
463 | $len = pack("c", 32 + 0.75*length); # compute length byte |
464 | print unpack("u", $len . $_); # uudecode and print |
465 | |
5a964f20 |
466 | =head2 How do I return the user's mail address? |
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467 | |
a6dd486b |
468 | On systems that support getpwuid, the $< variable, and the |
68dc0745 |
469 | Sys::Hostname module (which is part of the standard perl distribution), |
470 | you can probably try using something like this: |
471 | |
472 | use Sys::Hostname; |
231ab6d1 |
473 | $address = sprintf('%s@%s', scalar getpwuid($<), hostname); |
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474 | |
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475 | Company policies on mail address can mean that this generates addresses |
476 | that the company's mail system will not accept, so you should ask for |
477 | users' mail addresses when this matters. Furthermore, not all systems |
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478 | on which Perl runs are so forthcoming with this information as is Unix. |
479 | |
480 | The Mail::Util module from CPAN (part of the MailTools package) provides a |
481 | mailaddress() function that tries to guess the mail address of the user. |
482 | It makes a more intelligent guess than the code above, using information |
483 | given when the module was installed, but it could still be incorrect. |
484 | Again, the best way is often just to ask the user. |
485 | |
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486 | =head2 How do I send mail? |
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487 | |
c8db1d39 |
488 | Use the C<sendmail> program directly: |
489 | |
490 | open(SENDMAIL, "|/usr/lib/sendmail -oi -t -odq") |
491 | or die "Can't fork for sendmail: $!\n"; |
492 | print SENDMAIL <<"EOF"; |
493 | From: User Originating Mail <me\@host> |
494 | To: Final Destination <you\@otherhost> |
495 | Subject: A relevant subject line |
496 | |
65acb1b1 |
497 | Body of the message goes here after the blank line |
498 | in as many lines as you like. |
c8db1d39 |
499 | EOF |
500 | close(SENDMAIL) or warn "sendmail didn't close nicely"; |
501 | |
502 | The B<-oi> option prevents sendmail from interpreting a line consisting |
503 | of a single dot as "end of message". The B<-t> option says to use the |
504 | headers to decide who to send the message to, and B<-odq> says to put |
505 | the message into the queue. This last option means your message won't |
506 | be immediately delivered, so leave it out if you want immediate |
507 | delivery. |
508 | |
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509 | Alternate, less convenient approaches include calling mail (sometimes |
510 | called mailx) directly or simply opening up port 25 have having an |
511 | intimate conversation between just you and the remote SMTP daemon, |
512 | probably sendmail. |
513 | |
514 | Or you might be able use the CPAN module Mail::Mailer: |
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515 | |
516 | use Mail::Mailer; |
517 | |
518 | $mailer = Mail::Mailer->new(); |
519 | $mailer->open({ From => $from_address, |
520 | To => $to_address, |
521 | Subject => $subject, |
522 | }) |
523 | or die "Can't open: $!\n"; |
524 | print $mailer $body; |
525 | $mailer->close(); |
526 | |
527 | The Mail::Internet module uses Net::SMTP which is less Unix-centric than |
528 | Mail::Mailer, but less reliable. Avoid raw SMTP commands. There |
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529 | are many reasons to use a mail transport agent like sendmail. These |
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530 | include queuing, MX records, and security. |
c8db1d39 |
531 | |
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532 | =head2 How do I use MIME to make an attachment to a mail message? |
533 | |
534 | This answer is extracted directly from the MIME::Lite documentation. |
535 | Create a multipart message (i.e., one with attachments). |
536 | |
537 | use MIME::Lite; |
538 | |
539 | ### Create a new multipart message: |
540 | $msg = MIME::Lite->new( |
541 | From =>'me@myhost.com', |
542 | To =>'you@yourhost.com', |
543 | Cc =>'some@other.com, some@more.com', |
544 | Subject =>'A message with 2 parts...', |
545 | Type =>'multipart/mixed' |
546 | ); |
547 | |
548 | ### Add parts (each "attach" has same arguments as "new"): |
549 | $msg->attach(Type =>'TEXT', |
550 | Data =>"Here's the GIF file you wanted" |
551 | ); |
552 | $msg->attach(Type =>'image/gif', |
553 | Path =>'aaa000123.gif', |
554 | Filename =>'logo.gif' |
555 | ); |
556 | |
557 | $text = $msg->as_string; |
558 | |
559 | MIME::Lite also includes a method for sending these things. |
560 | |
561 | $msg->send; |
562 | |
197aec24 |
563 | This defaults to using L<sendmail> but can be customized to use |
575cc754 |
564 | SMTP via L<Net::SMTP>. |
565 | |
c8db1d39 |
566 | =head2 How do I read mail? |
567 | |
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568 | While you could use the Mail::Folder module from CPAN (part of the |
5cd0b561 |
569 | MailFolder package) or the Mail::Internet module from CPAN (part |
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570 | of the MailTools package), often a module is overkill. Here's a |
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571 | mail sorter. |
572 | |
573 | #!/usr/bin/perl |
5cd0b561 |
574 | |
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575 | my(@msgs, @sub); |
576 | my $msgno = -1; |
577 | $/ = ''; # paragraph reads |
578 | while (<>) { |
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579 | if (/^From /m) { |
c8db1d39 |
580 | /^Subject:\s*(?:Re:\s*)*(.*)/mi; |
581 | $sub[++$msgno] = lc($1) || ''; |
582 | } |
583 | $msgs[$msgno] .= $_; |
d92eb7b0 |
584 | } |
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585 | for my $i (sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msgs)) { |
586 | print $msgs[$i]; |
587 | } |
588 | |
d92eb7b0 |
589 | Or more succinctly, |
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590 | |
591 | #!/usr/bin/perl -n00 |
592 | # bysub2 - awkish sort-by-subject |
593 | BEGIN { $msgno = -1 } |
594 | $sub[++$msgno] = (/^Subject:\s*(?:Re:\s*)*(.*)/mi)[0] if /^From/m; |
595 | $msg[$msgno] .= $_; |
596 | END { print @msg[ sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msg) ] } |
597 | |
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598 | =head2 How do I find out my hostname, domainname, or IP address? |
599 | X<hostname, domainname, IP address, host, domain, hostfqdn, inet_ntoa, |
600 | gethostbyname, Socket, Net::Domain, Sys::Hostname> |
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601 | |
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602 | (contributed by brian d foy) |
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603 | |
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604 | The Net::Domain module, which is part of the standard distribution starting |
605 | in perl5.7.3, can get you the fully qualified domain name (FQDN), the host |
606 | name, or the domain name. |
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607 | |
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608 | use Net::Domain qw(hostname hostfqdn hostdomain); |
609 | |
610 | my $host = hostfqdn(); |
611 | |
612 | The C<Sys::Hostname> module, included in the standard distribution since |
613 | perl5.6, can also get the hostname. |
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614 | |
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615 | use Sys::Hostname; |
616 | |
617 | $host = hostname(); |
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618 | |
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619 | To get the IP address, you can use the C<gethostbyname> built-in function |
620 | to turn the name into a number. To turn that number into the dotted octet |
621 | form (a.b.c.d) that most people expect, use the C<inet_ntoa> function |
622 | from the <Socket> module, which also comes with perl. |
623 | |
624 | use Socket; |
625 | |
626 | my $address = inet_ntoa( |
627 | scalar gethostbyname( $host || 'localhost' ) |
628 | ); |
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629 | |
630 | =head2 How do I fetch a news article or the active newsgroups? |
631 | |
632 | Use the Net::NNTP or News::NNTPClient modules, both available from CPAN. |
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633 | This can make tasks like fetching the newsgroup list as simple as |
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634 | |
635 | perl -MNews::NNTPClient |
636 | -e 'print News::NNTPClient->new->list("newsgroups")' |
637 | |
638 | =head2 How do I fetch/put an FTP file? |
639 | |
640 | LWP::Simple (available from CPAN) can fetch but not put. Net::FTP (also |
641 | available from CPAN) is more complex but can put as well as fetch. |
642 | |
643 | =head2 How can I do RPC in Perl? |
644 | |
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645 | (Contributed by brian d foy) |
646 | |
647 | Use one of the RPC modules you can find on CPAN ( |
648 | http://search.cpan.org/search?query=RPC&mode=all ). |
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649 | |
650 | =head1 AUTHOR AND COPYRIGHT |
651 | |
7678cced |
652 | Copyright (c) 1997-2005 Tom Christiansen, Nathan Torkington, and |
653 | other authors as noted. All rights reserved. |
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654 | |
5a7beb56 |
655 | This documentation is free; you can redistribute it and/or modify it |
656 | under the same terms as Perl itself. |
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657 | |
658 | Irrespective of its distribution, all code examples in this file |
659 | are hereby placed into the public domain. You are permitted and |
660 | encouraged to use this code in your own programs for fun |
661 | or for profit as you see fit. A simple comment in the code giving |
662 | credit would be courteous but is not required. |