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68dc0745 | 1 | =head1 NAME |
2 | ||
ee891a00 | 3 | perlfaq9 - Networking ($Revision: 8539 $) |
68dc0745 | 4 | |
5 | =head1 DESCRIPTION | |
6 | ||
7 | This section deals with questions related to networking, the internet, | |
8 | and a few on the web. | |
9 | ||
24f1ba9b | 10 | =head2 What is the correct form of response from a CGI script? |
68dc0745 | 11 | |
24f1ba9b JH |
12 | (Alan Flavell <flavell+www@a5.ph.gla.ac.uk> answers...) |
13 | ||
197aec24 RGS |
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 | |
24f1ba9b | 18 | |
6670e5e7 RGS |
19 | The CGI specification is outlined in an informational RFC: |
20 | http://www.ietf.org/rfc/rfc3875 | |
24f1ba9b JH |
21 | |
22 | Other relevant documentation listed in: http://www.perl.org/CGI_MetaFAQ.html | |
68dc0745 | 23 | |
197aec24 | 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. |
68dc0745 | 27 | |
24f1ba9b JH |
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. | |
68dc0745 | 31 | |
24f1ba9b JH |
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. | |
68dc0745 | 43 | |
24f1ba9b JH |
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. | |
c8db1d39 | 47 | |
24f1ba9b | 48 | =head2 My CGI script runs from the command line but not the browser. (500 Server Error) |
c8db1d39 | 49 | |
0bc0ad85 JH |
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 JH |
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. | |
c8db1d39 | 62 | |
197aec24 | 63 | The useful FAQs, related documents, and troubleshooting guides are |
24f1ba9b JH |
64 | listed in the CGI Meta FAQ: |
65 | ||
66 | http://www.perl.org/CGI_MetaFAQ.html | |
c8db1d39 | 67 | |
c8db1d39 TC |
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 | ||
68dc0745 | 102 | =head2 How do I remove HTML from a string? |
103 | ||
f29c64d6 | 104 | The most correct way (albeit not the fastest) is to use HTML::Parser |
bed171df | 105 | from CPAN. Another mostly correct |
7d7e76cf MS |
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. | |
68dc0745 | 108 | |
109 | Many folks attempt a simple-minded regular expression approach, like | |
c47ff5f1 | 110 | C<< s/<.*?>//g >>, but that fails in many cases because the tags |
68dc0745 | 111 | may continue over line breaks, they may contain quoted angle-brackets, |
a6dd486b JB |
112 | or HTML comment may be present. Plus, folks forget to convert |
113 | entities--like C<<> for example. | |
68dc0745 | 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 | |
a93751fa | 122 | http://www.cpan.org/authors/Tom_Christiansen/scripts/striphtml.gz |
68dc0745 | 123 | . |
124 | ||
c8db1d39 TC |
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 TC |
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 | ||
68dc0745 | 148 | =head2 How do I extract URLs? |
149 | ||
e67d034e JH |
150 | You can easily extract all sorts of URLs from HTML with |
151 | C<HTML::SimpleLinkExtor> which handles anchors, images, objects, | |
197aec24 RGS |
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 | |
e67d034e JH |
155 | C<HTML::SimpleLinkExtor> as an example for something specifically |
156 | suited to your needs. | |
157 | ||
49d635f9 RGS |
158 | You can use URI::Find to extract URLs from an arbitrary text document. |
159 | ||
197aec24 | 160 | Less complete solutions involving regular expressions can save |
e67d034e JH |
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 | |
197aec24 | 164 | attribute is HREF and there are no other attributes. |
e67d034e JH |
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 | ||
68dc0745 | 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 RGS |
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. | |
68dc0745 | 188 | |
e573f903 RGS |
189 | =head2 How do I make an HTML pop-up menu with Perl? |
190 | ||
191 | (contributed by brian d foy) | |
192 | ||
193 | The CGI.pm module (which comes with Perl) has functions to create | |
194 | the HTML form widgets. See the CGI.pm documentation for more | |
195 | examples. | |
196 | ||
197 | use CGI qw/:standard/; | |
198 | print header, | |
199 | start_html('Favorite Animals'), | |
200 | ||
201 | start_form, | |
202 | "What's your favorite animal? ", | |
203 | popup_menu( | |
204 | -name => 'animal', | |
205 | -values => [ qw( Llama Alpaca Camel Ram ) ] | |
206 | ), | |
207 | submit, | |
208 | ||
209 | end_form, | |
210 | end_html; | |
68dc0745 | 211 | |
68dc0745 | 212 | |
213 | =head2 How do I fetch an HTML file? | |
214 | ||
46fc3d4c | 215 | One approach, if you have the lynx text-based HTML browser installed |
216 | on your system, is this: | |
68dc0745 | 217 | |
218 | $html_code = `lynx -source $url`; | |
219 | $text_data = `lynx -dump $url`; | |
220 | ||
d92eb7b0 GS |
221 | The libwww-perl (LWP) modules from CPAN provide a more powerful way |
222 | to do this. They don't require lynx, but like lynx, can still work | |
223 | through proxies: | |
46fc3d4c | 224 | |
c8db1d39 TC |
225 | # simplest version |
226 | use LWP::Simple; | |
227 | $content = get($URL); | |
228 | ||
229 | # or print HTML from a URL | |
46fc3d4c | 230 | use LWP::Simple; |
6cecdcac | 231 | getprint "http://www.linpro.no/lwp/"; |
46fc3d4c | 232 | |
c8db1d39 | 233 | # or print ASCII from HTML from a URL |
65acb1b1 | 234 | # also need HTML-Tree package from CPAN |
46fc3d4c | 235 | use LWP::Simple; |
f29c64d6 | 236 | use HTML::Parser; |
46fc3d4c | 237 | use HTML::FormatText; |
238 | my ($html, $ascii); | |
239 | $html = get("http://www.perl.com/"); | |
240 | defined $html | |
241 | or die "Can't fetch HTML from http://www.perl.com/"; | |
242 | $ascii = HTML::FormatText->new->format(parse_html($html)); | |
243 | print $ascii; | |
244 | ||
c8db1d39 TC |
245 | =head2 How do I automate an HTML form submission? |
246 | ||
7678cced RGS |
247 | If you are doing something complex, such as moving through many pages |
248 | and forms or a web site, you can use C<WWW::Mechanize>. See its | |
249 | documentation for all the details. | |
250 | ||
c8db1d39 TC |
251 | If you're submitting values using the GET method, create a URL and encode |
252 | the form using the C<query_form> method: | |
253 | ||
254 | use LWP::Simple; | |
255 | use URI::URL; | |
256 | ||
257 | my $url = url('http://www.perl.com/cgi-bin/cpan_mod'); | |
258 | $url->query_form(module => 'DB_File', readme => 1); | |
259 | $content = get($url); | |
260 | ||
261 | If you're using the POST method, create your own user agent and encode | |
262 | the content appropriately. | |
263 | ||
264 | use HTTP::Request::Common qw(POST); | |
265 | use LWP::UserAgent; | |
266 | ||
267 | $ua = LWP::UserAgent->new(); | |
268 | my $req = POST 'http://www.perl.com/cgi-bin/cpan_mod', | |
269 | [ module => 'DB_File', readme => 1 ]; | |
270 | $content = $ua->request($req)->as_string; | |
271 | ||
272 | =head2 How do I decode or create those %-encodings on the web? | |
68dc0745 | 273 | |
575cc754 JH |
274 | If you are writing a CGI script, you should be using the CGI.pm module |
275 | that comes with perl, or some other equivalent module. The CGI module | |
276 | automatically decodes queries for you, and provides an escape() | |
277 | function to handle encoding. | |
68dc0745 | 278 | |
575cc754 JH |
279 | The best source of detailed information on URI encoding is RFC 2396. |
280 | Basically, the following substitutions do it: | |
281 | ||
48a4adce | 282 | s/([^\w()'*~!.-])/sprintf '%%%02x', ord $1/eg; # encode |
575cc754 | 283 | |
a05e4845 RGS |
284 | s/%([A-Fa-f\d]{2})/chr hex $1/eg; # decode |
285 | s/%([[:xdigit:]]{2})/chr hex $1/eg; # same thing | |
575cc754 JH |
286 | |
287 | However, you should only apply them to individual URI components, not | |
288 | the entire URI, otherwise you'll lose information and generally mess | |
289 | things up. If that didn't explain it, don't worry. Just go read | |
290 | section 2 of the RFC, it's probably the best explanation there is. | |
291 | ||
292 | RFC 2396 also contains a lot of other useful information, including a | |
293 | regexp for breaking any arbitrary URI into components (Appendix B). | |
68dc0745 | 294 | |
295 | =head2 How do I redirect to another page? | |
296 | ||
24f1ba9b JH |
297 | Specify the complete URL of the destination (even if it is on the same |
298 | server). This is one of the two different kinds of CGI "Location:" | |
299 | responses which are defined in the CGI specification for a Parsed Headers | |
300 | script. The other kind (an absolute URLpath) is resolved internally to | |
301 | the server without any HTTP redirection. The CGI specifications do not | |
302 | allow relative URLs in either case. | |
303 | ||
304 | Use of CGI.pm is strongly recommended. This example shows redirection | |
305 | with a complete URL. This redirection is handled by the web browser. | |
306 | ||
307 | use CGI qw/:standard/; | |
308 | ||
a93751fa | 309 | my $url = 'http://www.cpan.org/'; |
24f1ba9b | 310 | print redirect($url); |
68dc0745 | 311 | |
68dc0745 | 312 | |
24f1ba9b JH |
313 | This example shows a redirection with an absolute URLpath. This |
314 | redirection is handled by the local web server. | |
68dc0745 | 315 | |
24f1ba9b JH |
316 | my $url = '/CPAN/index.html'; |
317 | print redirect($url); | |
c8db1d39 | 318 | |
d92eb7b0 | 319 | |
197aec24 | 320 | But if coded directly, it could be as follows (the final "\n" is |
24f1ba9b | 321 | shown separately, for clarity), using either a complete URL or |
197aec24 | 322 | an absolute URLpath. |
d92eb7b0 | 323 | |
24f1ba9b JH |
324 | print "Location: $url\n"; # CGI response header |
325 | print "\n"; # end of headers | |
d92eb7b0 | 326 | |
c8db1d39 | 327 | |
68dc0745 | 328 | =head2 How do I put a password on my web pages? |
329 | ||
49d635f9 RGS |
330 | To enable authentication for your web server, you need to configure |
331 | your web server. The configuration is different for different sorts | |
ac9dac7f | 332 | of web servers--apache does it differently from iPlanet which does |
49d635f9 RGS |
333 | it differently from IIS. Check your web server documentation for |
334 | the details for your particular server. | |
68dc0745 | 335 | |
336 | =head2 How do I edit my .htpasswd and .htgroup files with Perl? | |
337 | ||
338 | The HTTPD::UserAdmin and HTTPD::GroupAdmin modules provide a | |
339 | consistent OO interface to these files, regardless of how they're | |
426affbf LS |
340 | stored. Databases may be text, dbm, Berkeley DB or any database with |
341 | a DBI compatible driver. HTTPD::UserAdmin supports files used by the | |
b432a672 | 342 | "Basic" and "Digest" authentication schemes. Here's an example: |
68dc0745 | 343 | |
344 | use HTTPD::UserAdmin (); | |
345 | HTTPD::UserAdmin | |
346 | ->new(DB => "/foo/.htpasswd") | |
347 | ->add($username => $password); | |
348 | ||
46fc3d4c | 349 | =head2 How do I make sure users can't enter values into a form that cause my CGI script to do bad things? |
350 | ||
24f1ba9b | 351 | See the security references listed in the CGI Meta FAQ |
46fc3d4c | 352 | |
24f1ba9b | 353 | http://www.perl.org/CGI_MetaFAQ.html |
46fc3d4c | 354 | |
5a964f20 | 355 | =head2 How do I parse a mail header? |
68dc0745 | 356 | |
357 | For a quick-and-dirty solution, try this solution derived | |
b73a15ae | 358 | from L<perlfunc/split>: |
68dc0745 | 359 | |
360 | $/ = ''; | |
361 | $header = <MSG>; | |
362 | $header =~ s/\n\s+/ /g; # merge continuation lines | |
363 | %head = ( UNIX_FROM_LINE, split /^([-\w]+):\s*/m, $header ); | |
364 | ||
365 | That solution doesn't do well if, for example, you're trying to | |
366 | maintain all the Received lines. A more complete approach is to use | |
367 | the Mail::Header module from CPAN (part of the MailTools package). | |
368 | ||
369 | =head2 How do I decode a CGI form? | |
370 | ||
7678cced RGS |
371 | (contributed by brian d foy) |
372 | ||
373 | Use the CGI.pm module that comes with Perl. It's quick, | |
374 | it's easy, and it actually does quite a bit of work to | |
375 | ensure things happen correctly. It handles GET, POST, and | |
376 | HEAD requests, multipart forms, multivalued fields, query | |
377 | string and message body combinations, and many other things | |
378 | you probably don't want to think about. | |
379 | ||
380 | It doesn't get much easier: the CGI module automatically | |
381 | parses the input and makes each value available through the | |
382 | C<param()> function. | |
383 | ||
384 | use CGI qw(:standard); | |
6670e5e7 | 385 | |
9e72e4c6 | 386 | my $total = param( 'price' ) + param( 'shipping' ); |
6670e5e7 | 387 | |
9e72e4c6 | 388 | my @items = param( 'item' ); # multiple values, same field name |
6670e5e7 | 389 | |
7678cced RGS |
390 | If you want an object-oriented approach, CGI.pm can do that too. |
391 | ||
392 | use CGI; | |
6670e5e7 | 393 | |
7678cced | 394 | my $cgi = CGI->new(); |
6670e5e7 | 395 | |
9e72e4c6 | 396 | my $total = $cgi->param( 'price' ) + $cgi->param( 'shipping' ); |
6670e5e7 | 397 | |
9e72e4c6 | 398 | my @items = $cgi->param( 'item' ); |
7678cced RGS |
399 | |
400 | You might also try CGI::Minimal which is a lightweight version | |
401 | of the same thing. Other CGI::* modules on CPAN might work better | |
402 | for you, too. | |
403 | ||
404 | Many people try to write their own decoder (or copy one from | |
405 | another program) and then run into one of the many "gotchas" | |
406 | of the task. It's much easier and less hassle to use CGI.pm. | |
68dc0745 | 407 | |
5a964f20 | 408 | =head2 How do I check a valid mail address? |
68dc0745 | 409 | |
322be77c | 410 | (partly contributed by Aaron Sherman) |
68dc0745 | 411 | |
322be77c | 412 | This isn't as simple a question as it sounds. There are two parts: |
c8db1d39 | 413 | |
322be77c | 414 | a) How do I verify that an email address is correctly formatted? |
c8db1d39 | 415 | |
322be77c | 416 | b) How do I verify that an email address targets a valid recipient? |
c8db1d39 | 417 | |
322be77c RGS |
418 | Without sending mail to the address and seeing whether there's a human |
419 | on the other end to answer you, you cannot fully answer part I<b>, but | |
420 | either the C<Email::Valid> or the C<RFC::RFC822::Address> module will do | |
421 | both part I<a> and part I<b> as far as you can in real-time. | |
422 | ||
423 | If you want to just check part I<a> to see that the address is valid | |
424 | according to the mail header standard with a simple regular expression, | |
425 | you can have problems, because there are deliverable addresses that | |
426 | aren't RFC-2822 (the latest mail header standard) compliant, and | |
427 | addresses that aren't deliverable which, are compliant. However, the | |
428 | following will match valid RFC-2822 addresses that do not have comments, | |
429 | folding whitespace, or any other obsolete or non-essential elements. | |
430 | This I<just> matches the address itself: | |
431 | ||
432 | my $atom = qr{[a-zA-Z0-9_!#\$\%&'*+/=?\^`{}~|\-]+}; | |
433 | my $dot_atom = qr{$atom(?:\.$atom)*}; | |
434 | my $quoted = qr{"(?:\\[^\r\n]|[^\\"])*"}; | |
435 | my $local = qr{(?:$dot_atom|$quoted)}; | |
436 | my $domain_lit = qr{\[(?:\\\S|[\x21-\x5a\x5e-\x7e])*\]}; | |
437 | my $domain = qr{(?:$dot_atom|$domain_lit)}; | |
438 | my $addr_spec = qr{$local\@$domain}; | |
439 | ||
440 | Just match an address against C</^${addr_spec}$/> to see if it follows | |
441 | the RFC2822 specification. However, because it is impossible to be | |
442 | sure that such a correctly formed address is actually the correct way | |
443 | to reach a particular person or even has a mailbox associated with it, | |
444 | you must be very careful about how you use this. | |
c8db1d39 | 445 | |
322be77c RGS |
446 | Our best advice for verifying a person's mail address is to have them |
447 | enter their address twice, just as you normally do to change a | |
448 | password. This usually weeds out typos. If both versions match, send | |
449 | mail to that address with a personal message. If you get the message | |
450 | back and they've followed your directions, you can be reasonably | |
451 | assured that it's real. | |
68dc0745 | 452 | |
c8db1d39 TC |
453 | A related strategy that's less open to forgery is to give them a PIN |
454 | (personal ID number). Record the address and PIN (best that it be a | |
322be77c | 455 | random one) for later processing. In the mail you send, ask them to |
c8db1d39 | 456 | include the PIN in their reply. But if it bounces, or the message is |
b432a672 | 457 | included via a "vacation" script, it'll be there anyway. So it's |
c8db1d39 TC |
458 | best to ask them to mail back a slight alteration of the PIN, such as |
459 | with the characters reversed, one added or subtracted to each digit, etc. | |
46fc3d4c | 460 | |
68dc0745 | 461 | =head2 How do I decode a MIME/BASE64 string? |
462 | ||
6a0af2f1 GA |
463 | The MIME-Base64 package (available from CPAN) handles this as well as |
464 | the MIME/QP encoding. Decoding BASE64 becomes as simple as: | |
68dc0745 | 465 | |
6a0af2f1 | 466 | use MIME::Base64; |
68dc0745 | 467 | $decoded = decode_base64($encoded); |
468 | ||
26d9b02f | 469 | The MIME-Tools package (available from CPAN) supports extraction with |
6a0af2f1 GA |
470 | decoding of BASE64 encoded attachments and content directly from email |
471 | messages. | |
472 | ||
473 | If the string to decode is short (less than 84 bytes long) | |
474 | a more direct approach is to use the unpack() function's "u" | |
68dc0745 | 475 | format after minor transliterations: |
476 | ||
477 | tr#A-Za-z0-9+/##cd; # remove non-base64 chars | |
478 | tr#A-Za-z0-9+/# -_#; # convert to uuencoded format | |
479 | $len = pack("c", 32 + 0.75*length); # compute length byte | |
480 | print unpack("u", $len . $_); # uudecode and print | |
481 | ||
5a964f20 | 482 | =head2 How do I return the user's mail address? |
68dc0745 | 483 | |
a6dd486b | 484 | On systems that support getpwuid, the $< variable, and the |
68dc0745 | 485 | Sys::Hostname module (which is part of the standard perl distribution), |
486 | you can probably try using something like this: | |
487 | ||
488 | use Sys::Hostname; | |
231ab6d1 | 489 | $address = sprintf('%s@%s', scalar getpwuid($<), hostname); |
68dc0745 | 490 | |
5a964f20 TC |
491 | Company policies on mail address can mean that this generates addresses |
492 | that the company's mail system will not accept, so you should ask for | |
493 | users' mail addresses when this matters. Furthermore, not all systems | |
68dc0745 | 494 | on which Perl runs are so forthcoming with this information as is Unix. |
495 | ||
496 | The Mail::Util module from CPAN (part of the MailTools package) provides a | |
497 | mailaddress() function that tries to guess the mail address of the user. | |
498 | It makes a more intelligent guess than the code above, using information | |
499 | given when the module was installed, but it could still be incorrect. | |
500 | Again, the best way is often just to ask the user. | |
501 | ||
c8db1d39 | 502 | =head2 How do I send mail? |
68dc0745 | 503 | |
c8db1d39 TC |
504 | Use the C<sendmail> program directly: |
505 | ||
506 | open(SENDMAIL, "|/usr/lib/sendmail -oi -t -odq") | |
507 | or die "Can't fork for sendmail: $!\n"; | |
508 | print SENDMAIL <<"EOF"; | |
509 | From: User Originating Mail <me\@host> | |
510 | To: Final Destination <you\@otherhost> | |
511 | Subject: A relevant subject line | |
512 | ||
65acb1b1 TC |
513 | Body of the message goes here after the blank line |
514 | in as many lines as you like. | |
c8db1d39 TC |
515 | EOF |
516 | close(SENDMAIL) or warn "sendmail didn't close nicely"; | |
517 | ||
518 | The B<-oi> option prevents sendmail from interpreting a line consisting | |
519 | of a single dot as "end of message". The B<-t> option says to use the | |
520 | headers to decide who to send the message to, and B<-odq> says to put | |
521 | the message into the queue. This last option means your message won't | |
522 | be immediately delivered, so leave it out if you want immediate | |
523 | delivery. | |
524 | ||
d92eb7b0 GS |
525 | Alternate, less convenient approaches include calling mail (sometimes |
526 | called mailx) directly or simply opening up port 25 have having an | |
527 | intimate conversation between just you and the remote SMTP daemon, | |
528 | probably sendmail. | |
529 | ||
530 | Or you might be able use the CPAN module Mail::Mailer: | |
c8db1d39 TC |
531 | |
532 | use Mail::Mailer; | |
533 | ||
534 | $mailer = Mail::Mailer->new(); | |
535 | $mailer->open({ From => $from_address, | |
536 | To => $to_address, | |
537 | Subject => $subject, | |
538 | }) | |
539 | or die "Can't open: $!\n"; | |
540 | print $mailer $body; | |
541 | $mailer->close(); | |
542 | ||
543 | The Mail::Internet module uses Net::SMTP which is less Unix-centric than | |
544 | Mail::Mailer, but less reliable. Avoid raw SMTP commands. There | |
d92eb7b0 | 545 | are many reasons to use a mail transport agent like sendmail. These |
8305e449 | 546 | include queuing, MX records, and security. |
c8db1d39 | 547 | |
575cc754 JH |
548 | =head2 How do I use MIME to make an attachment to a mail message? |
549 | ||
550 | This answer is extracted directly from the MIME::Lite documentation. | |
551 | Create a multipart message (i.e., one with attachments). | |
552 | ||
553 | use MIME::Lite; | |
554 | ||
555 | ### Create a new multipart message: | |
556 | $msg = MIME::Lite->new( | |
557 | From =>'me@myhost.com', | |
558 | To =>'you@yourhost.com', | |
559 | Cc =>'some@other.com, some@more.com', | |
560 | Subject =>'A message with 2 parts...', | |
561 | Type =>'multipart/mixed' | |
562 | ); | |
563 | ||
564 | ### Add parts (each "attach" has same arguments as "new"): | |
565 | $msg->attach(Type =>'TEXT', | |
566 | Data =>"Here's the GIF file you wanted" | |
567 | ); | |
568 | $msg->attach(Type =>'image/gif', | |
569 | Path =>'aaa000123.gif', | |
570 | Filename =>'logo.gif' | |
571 | ); | |
572 | ||
573 | $text = $msg->as_string; | |
574 | ||
575 | MIME::Lite also includes a method for sending these things. | |
576 | ||
577 | $msg->send; | |
578 | ||
197aec24 | 579 | This defaults to using L<sendmail> but can be customized to use |
575cc754 JH |
580 | SMTP via L<Net::SMTP>. |
581 | ||
c8db1d39 TC |
582 | =head2 How do I read mail? |
583 | ||
d92eb7b0 | 584 | While you could use the Mail::Folder module from CPAN (part of the |
5cd0b561 | 585 | MailFolder package) or the Mail::Internet module from CPAN (part |
a6dd486b | 586 | of the MailTools package), often a module is overkill. Here's a |
d92eb7b0 GS |
587 | mail sorter. |
588 | ||
589 | #!/usr/bin/perl | |
5cd0b561 | 590 | |
c8db1d39 TC |
591 | my(@msgs, @sub); |
592 | my $msgno = -1; | |
593 | $/ = ''; # paragraph reads | |
594 | while (<>) { | |
5cd0b561 | 595 | if (/^From /m) { |
c8db1d39 TC |
596 | /^Subject:\s*(?:Re:\s*)*(.*)/mi; |
597 | $sub[++$msgno] = lc($1) || ''; | |
598 | } | |
599 | $msgs[$msgno] .= $_; | |
d92eb7b0 | 600 | } |
c8db1d39 TC |
601 | for my $i (sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msgs)) { |
602 | print $msgs[$i]; | |
603 | } | |
604 | ||
d92eb7b0 | 605 | Or more succinctly, |
c8db1d39 TC |
606 | |
607 | #!/usr/bin/perl -n00 | |
608 | # bysub2 - awkish sort-by-subject | |
609 | BEGIN { $msgno = -1 } | |
610 | $sub[++$msgno] = (/^Subject:\s*(?:Re:\s*)*(.*)/mi)[0] if /^From/m; | |
611 | $msg[$msgno] .= $_; | |
612 | END { print @msg[ sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msg) ] } | |
613 | ||
a05e4845 RGS |
614 | =head2 How do I find out my hostname, domainname, or IP address? |
615 | X<hostname, domainname, IP address, host, domain, hostfqdn, inet_ntoa, | |
616 | gethostbyname, Socket, Net::Domain, Sys::Hostname> | |
68dc0745 | 617 | |
a05e4845 | 618 | (contributed by brian d foy) |
68dc0745 | 619 | |
a05e4845 RGS |
620 | The Net::Domain module, which is part of the standard distribution starting |
621 | in perl5.7.3, can get you the fully qualified domain name (FQDN), the host | |
622 | name, or the domain name. | |
68dc0745 | 623 | |
a05e4845 | 624 | use Net::Domain qw(hostname hostfqdn hostdomain); |
58103a2e | 625 | |
a05e4845 RGS |
626 | my $host = hostfqdn(); |
627 | ||
628 | The C<Sys::Hostname> module, included in the standard distribution since | |
629 | perl5.6, can also get the hostname. | |
68dc0745 | 630 | |
a05e4845 | 631 | use Sys::Hostname; |
58103a2e | 632 | |
a05e4845 | 633 | $host = hostname(); |
68dc0745 | 634 | |
a05e4845 RGS |
635 | To get the IP address, you can use the C<gethostbyname> built-in function |
636 | to turn the name into a number. To turn that number into the dotted octet | |
637 | form (a.b.c.d) that most people expect, use the C<inet_ntoa> function | |
638 | from the <Socket> module, which also comes with perl. | |
639 | ||
640 | use Socket; | |
58103a2e RGS |
641 | |
642 | my $address = inet_ntoa( | |
a05e4845 RGS |
643 | scalar gethostbyname( $host || 'localhost' ) |
644 | ); | |
68dc0745 | 645 | |
646 | =head2 How do I fetch a news article or the active newsgroups? | |
647 | ||
648 | Use the Net::NNTP or News::NNTPClient modules, both available from CPAN. | |
a6dd486b | 649 | This can make tasks like fetching the newsgroup list as simple as |
68dc0745 | 650 | |
651 | perl -MNews::NNTPClient | |
652 | -e 'print News::NNTPClient->new->list("newsgroups")' | |
653 | ||
654 | =head2 How do I fetch/put an FTP file? | |
655 | ||
656 | LWP::Simple (available from CPAN) can fetch but not put. Net::FTP (also | |
657 | available from CPAN) is more complex but can put as well as fetch. | |
658 | ||
659 | =head2 How can I do RPC in Perl? | |
660 | ||
b68463f7 RGS |
661 | (Contributed by brian d foy) |
662 | ||
663 | Use one of the RPC modules you can find on CPAN ( | |
664 | http://search.cpan.org/search?query=RPC&mode=all ). | |
68dc0745 | 665 | |
500071f4 RGS |
666 | =head1 REVISION |
667 | ||
ee891a00 | 668 | Revision: $Revision: 8539 $ |
500071f4 | 669 | |
f449fe8a | 670 | Date: $Date: 2007-01-11 00:07:14 +0100 (Thu, 11 Jan 2007) $ |
500071f4 RGS |
671 | |
672 | See L<perlfaq> for source control details and availability. | |
673 | ||
68dc0745 | 674 | =head1 AUTHOR AND COPYRIGHT |
675 | ||
ee891a00 | 676 | Copyright (c) 1997-2007 Tom Christiansen, Nathan Torkington, and |
7678cced | 677 | other authors as noted. All rights reserved. |
5a964f20 | 678 | |
5a7beb56 JH |
679 | This documentation is free; you can redistribute it and/or modify it |
680 | under the same terms as Perl itself. | |
5a964f20 TC |
681 | |
682 | Irrespective of its distribution, all code examples in this file | |
683 | are hereby placed into the public domain. You are permitted and | |
684 | encouraged to use this code in your own programs for fun | |
685 | or for profit as you see fit. A simple comment in the code giving | |
686 | credit would be courteous but is not required. |