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68dc0745 | 1 | =head1 NAME |
2 | ||
b68463f7 | 3 | perlfaq9 - Networking ($Revision: 1.23 $, $Date: 2005/08/10 15:54:54 $) |
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 | |
189 | =head2 How do I make a pop-up menu in HTML? | |
190 | ||
c47ff5f1 | 191 | Use the B<< <SELECT> >> and B<< <OPTION> >> tags. The CGI.pm |
68dc0745 | 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 | ||
46fc3d4c | 197 | One approach, if you have the lynx text-based HTML browser installed |
198 | on your system, is this: | |
68dc0745 | 199 | |
200 | $html_code = `lynx -source $url`; | |
201 | $text_data = `lynx -dump $url`; | |
202 | ||
d92eb7b0 GS |
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 | |
c8db1d39 TC |
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 | |
c8db1d39 | 215 | # or print ASCII from HTML from a URL |
65acb1b1 | 216 | # also need HTML-Tree package from CPAN |
46fc3d4c | 217 | use LWP::Simple; |
f29c64d6 | 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 TC |
227 | =head2 How do I automate an HTML form submission? |
228 | ||
7678cced RGS |
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 | ||
c8db1d39 TC |
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? | |
68dc0745 | 255 | |
68dc0745 | 256 | |
575cc754 JH |
257 | If you are writing a CGI script, you should be using the CGI.pm module |
258 | that comes with perl, or some other equivalent module. The CGI module | |
259 | automatically decodes queries for you, and provides an escape() | |
260 | function to handle encoding. | |
68dc0745 | 261 | |
575cc754 JH |
262 | |
263 | The best source of detailed information on URI encoding is RFC 2396. | |
264 | Basically, the following substitutions do it: | |
265 | ||
48a4adce | 266 | s/([^\w()'*~!.-])/sprintf '%%%02x', ord $1/eg; # encode |
575cc754 | 267 | |
f05bbc40 | 268 | s/%([A-Fa-f\d]{2})/chr hex $1/eg; # decode |
575cc754 JH |
269 | |
270 | However, you should only apply them to individual URI components, not | |
271 | the entire URI, otherwise you'll lose information and generally mess | |
272 | things up. If that didn't explain it, don't worry. Just go read | |
273 | section 2 of the RFC, it's probably the best explanation there is. | |
274 | ||
275 | RFC 2396 also contains a lot of other useful information, including a | |
276 | regexp for breaking any arbitrary URI into components (Appendix B). | |
68dc0745 | 277 | |
278 | =head2 How do I redirect to another page? | |
279 | ||
24f1ba9b JH |
280 | Specify the complete URL of the destination (even if it is on the same |
281 | server). This is one of the two different kinds of CGI "Location:" | |
282 | responses which are defined in the CGI specification for a Parsed Headers | |
283 | script. The other kind (an absolute URLpath) is resolved internally to | |
284 | the server without any HTTP redirection. The CGI specifications do not | |
285 | allow relative URLs in either case. | |
286 | ||
287 | Use of CGI.pm is strongly recommended. This example shows redirection | |
288 | with a complete URL. This redirection is handled by the web browser. | |
289 | ||
290 | use CGI qw/:standard/; | |
291 | ||
a93751fa | 292 | my $url = 'http://www.cpan.org/'; |
24f1ba9b | 293 | print redirect($url); |
68dc0745 | 294 | |
68dc0745 | 295 | |
24f1ba9b JH |
296 | This example shows a redirection with an absolute URLpath. This |
297 | redirection is handled by the local web server. | |
68dc0745 | 298 | |
24f1ba9b JH |
299 | my $url = '/CPAN/index.html'; |
300 | print redirect($url); | |
c8db1d39 | 301 | |
d92eb7b0 | 302 | |
197aec24 | 303 | But if coded directly, it could be as follows (the final "\n" is |
24f1ba9b | 304 | shown separately, for clarity), using either a complete URL or |
197aec24 | 305 | an absolute URLpath. |
d92eb7b0 | 306 | |
24f1ba9b JH |
307 | print "Location: $url\n"; # CGI response header |
308 | print "\n"; # end of headers | |
d92eb7b0 | 309 | |
c8db1d39 | 310 | |
68dc0745 | 311 | =head2 How do I put a password on my web pages? |
312 | ||
49d635f9 RGS |
313 | To enable authentication for your web server, you need to configure |
314 | your web server. The configuration is different for different sorts | |
315 | of web servers---apache does it differently from iPlanet which does | |
316 | it differently from IIS. Check your web server documentation for | |
317 | the details for your particular server. | |
68dc0745 | 318 | |
319 | =head2 How do I edit my .htpasswd and .htgroup files with Perl? | |
320 | ||
321 | The HTTPD::UserAdmin and HTTPD::GroupAdmin modules provide a | |
322 | consistent OO interface to these files, regardless of how they're | |
426affbf LS |
323 | stored. Databases may be text, dbm, Berkeley DB or any database with |
324 | a DBI compatible driver. HTTPD::UserAdmin supports files used by the | |
b432a672 | 325 | "Basic" and "Digest" authentication schemes. Here's an example: |
68dc0745 | 326 | |
327 | use HTTPD::UserAdmin (); | |
328 | HTTPD::UserAdmin | |
329 | ->new(DB => "/foo/.htpasswd") | |
330 | ->add($username => $password); | |
331 | ||
46fc3d4c | 332 | =head2 How do I make sure users can't enter values into a form that cause my CGI script to do bad things? |
333 | ||
24f1ba9b | 334 | See the security references listed in the CGI Meta FAQ |
46fc3d4c | 335 | |
24f1ba9b | 336 | http://www.perl.org/CGI_MetaFAQ.html |
46fc3d4c | 337 | |
5a964f20 | 338 | =head2 How do I parse a mail header? |
68dc0745 | 339 | |
340 | For a quick-and-dirty solution, try this solution derived | |
b73a15ae | 341 | from L<perlfunc/split>: |
68dc0745 | 342 | |
343 | $/ = ''; | |
344 | $header = <MSG>; | |
345 | $header =~ s/\n\s+/ /g; # merge continuation lines | |
346 | %head = ( UNIX_FROM_LINE, split /^([-\w]+):\s*/m, $header ); | |
347 | ||
348 | That solution doesn't do well if, for example, you're trying to | |
349 | maintain all the Received lines. A more complete approach is to use | |
350 | the Mail::Header module from CPAN (part of the MailTools package). | |
351 | ||
352 | =head2 How do I decode a CGI form? | |
353 | ||
7678cced RGS |
354 | (contributed by brian d foy) |
355 | ||
356 | Use the CGI.pm module that comes with Perl. It's quick, | |
357 | it's easy, and it actually does quite a bit of work to | |
358 | ensure things happen correctly. It handles GET, POST, and | |
359 | HEAD requests, multipart forms, multivalued fields, query | |
360 | string and message body combinations, and many other things | |
361 | you probably don't want to think about. | |
362 | ||
363 | It doesn't get much easier: the CGI module automatically | |
364 | parses the input and makes each value available through the | |
365 | C<param()> function. | |
366 | ||
367 | use CGI qw(:standard); | |
6670e5e7 | 368 | |
7678cced | 369 | my $total = param( "price" ) + param( "shipping" ); |
6670e5e7 | 370 | |
7678cced | 371 | my @items = param( "item ); # multiple values, same field name |
6670e5e7 | 372 | |
7678cced RGS |
373 | If you want an object-oriented approach, CGI.pm can do that too. |
374 | ||
375 | use CGI; | |
6670e5e7 | 376 | |
7678cced | 377 | my $cgi = CGI->new(); |
6670e5e7 | 378 | |
7678cced | 379 | my $total = $cgi->param( "price" ) + $cgi->param( "shipping" ); |
6670e5e7 | 380 | |
7678cced RGS |
381 | my @items = $cgi->param( "item" ); |
382 | ||
383 | You might also try CGI::Minimal which is a lightweight version | |
384 | of the same thing. Other CGI::* modules on CPAN might work better | |
385 | for you, too. | |
386 | ||
387 | Many people try to write their own decoder (or copy one from | |
388 | another program) and then run into one of the many "gotchas" | |
389 | of the task. It's much easier and less hassle to use CGI.pm. | |
68dc0745 | 390 | |
5a964f20 | 391 | =head2 How do I check a valid mail address? |
68dc0745 | 392 | |
c8db1d39 | 393 | You can't, at least, not in real time. Bummer, eh? |
68dc0745 | 394 | |
c8db1d39 | 395 | Without sending mail to the address and seeing whether there's a human |
c98c5709 | 396 | on the other end to answer you, you cannot determine whether a mail |
c8db1d39 TC |
397 | address is valid. Even if you apply the mail header standard, you |
398 | can have problems, because there are deliverable addresses that aren't | |
399 | RFC-822 (the mail header standard) compliant, and addresses that aren't | |
400 | deliverable which are compliant. | |
68dc0745 | 401 | |
49d635f9 RGS |
402 | You can use the Email::Valid or RFC::RFC822::Address which check |
403 | the format of the address, although they cannot actually tell you | |
404 | if it is a deliverable address (i.e. that mail to the address | |
405 | will not bounce). Modules like Mail::CheckUser and Mail::EXPN | |
406 | try to interact with the domain name system or particular | |
407 | mail servers to learn even more, but their methods do not | |
408 | work everywhere---especially for security conscious administrators. | |
409 | ||
c8db1d39 | 410 | Many are tempted to try to eliminate many frequently-invalid |
d92eb7b0 | 411 | mail addresses with a simple regex, such as |
b8c8cfe2 | 412 | C</^[\w.-]+\@(?:[\w-]+\.)+\w+$/>. It's a very bad idea. However, |
c8db1d39 | 413 | this also throws out many valid ones, and says nothing about |
b8c8cfe2 | 414 | potential deliverability, so it is not suggested. Instead, see |
1577cd80 | 415 | http://www.cpan.org/authors/Tom_Christiansen/scripts/ckaddr.gz , |
68dc0745 | 416 | which actually checks against the full RFC spec (except for nested |
5a964f20 | 417 | comments), looks for addresses you may not wish to accept mail to |
68dc0745 | 418 | (say, Bill Clinton or your postmaster), and then makes sure that the |
c8db1d39 TC |
419 | hostname given can be looked up in the DNS MX records. It's not fast, |
420 | but it works for what it tries to do. | |
421 | ||
422 | Our best advice for verifying a person's mail address is to have them | |
423 | enter their address twice, just as you normally do to change a password. | |
424 | This usually weeds out typos. If both versions match, send | |
425 | mail to that address with a personal message that looks somewhat like: | |
426 | ||
427 | Dear someuser@host.com, | |
428 | ||
429 | Please confirm the mail address you gave us Wed May 6 09:38:41 | |
430 | MDT 1998 by replying to this message. Include the string | |
431 | "Rumpelstiltskin" in that reply, but spelled in reverse; that is, | |
432 | start with "Nik...". Once this is done, your confirmed address will | |
433 | be entered into our records. | |
434 | ||
435 | If you get the message back and they've followed your directions, | |
436 | you can be reasonably assured that it's real. | |
68dc0745 | 437 | |
c8db1d39 TC |
438 | A related strategy that's less open to forgery is to give them a PIN |
439 | (personal ID number). Record the address and PIN (best that it be a | |
440 | random one) for later processing. In the mail you send, ask them to | |
441 | include the PIN in their reply. But if it bounces, or the message is | |
b432a672 | 442 | included via a "vacation" script, it'll be there anyway. So it's |
c8db1d39 TC |
443 | best to ask them to mail back a slight alteration of the PIN, such as |
444 | with the characters reversed, one added or subtracted to each digit, etc. | |
46fc3d4c | 445 | |
68dc0745 | 446 | =head2 How do I decode a MIME/BASE64 string? |
447 | ||
6a0af2f1 GA |
448 | The MIME-Base64 package (available from CPAN) handles this as well as |
449 | the MIME/QP encoding. Decoding BASE64 becomes as simple as: | |
68dc0745 | 450 | |
6a0af2f1 | 451 | use MIME::Base64; |
68dc0745 | 452 | $decoded = decode_base64($encoded); |
453 | ||
26d9b02f | 454 | The MIME-Tools package (available from CPAN) supports extraction with |
6a0af2f1 GA |
455 | decoding of BASE64 encoded attachments and content directly from email |
456 | messages. | |
457 | ||
458 | If the string to decode is short (less than 84 bytes long) | |
459 | a more direct approach is to use the unpack() function's "u" | |
68dc0745 | 460 | format after minor transliterations: |
461 | ||
462 | tr#A-Za-z0-9+/##cd; # remove non-base64 chars | |
463 | tr#A-Za-z0-9+/# -_#; # convert to uuencoded format | |
464 | $len = pack("c", 32 + 0.75*length); # compute length byte | |
465 | print unpack("u", $len . $_); # uudecode and print | |
466 | ||
5a964f20 | 467 | =head2 How do I return the user's mail address? |
68dc0745 | 468 | |
a6dd486b | 469 | On systems that support getpwuid, the $< variable, and the |
68dc0745 | 470 | Sys::Hostname module (which is part of the standard perl distribution), |
471 | you can probably try using something like this: | |
472 | ||
473 | use Sys::Hostname; | |
231ab6d1 | 474 | $address = sprintf('%s@%s', scalar getpwuid($<), hostname); |
68dc0745 | 475 | |
5a964f20 TC |
476 | Company policies on mail address can mean that this generates addresses |
477 | that the company's mail system will not accept, so you should ask for | |
478 | users' mail addresses when this matters. Furthermore, not all systems | |
68dc0745 | 479 | on which Perl runs are so forthcoming with this information as is Unix. |
480 | ||
481 | The Mail::Util module from CPAN (part of the MailTools package) provides a | |
482 | mailaddress() function that tries to guess the mail address of the user. | |
483 | It makes a more intelligent guess than the code above, using information | |
484 | given when the module was installed, but it could still be incorrect. | |
485 | Again, the best way is often just to ask the user. | |
486 | ||
c8db1d39 | 487 | =head2 How do I send mail? |
68dc0745 | 488 | |
c8db1d39 TC |
489 | Use the C<sendmail> program directly: |
490 | ||
491 | open(SENDMAIL, "|/usr/lib/sendmail -oi -t -odq") | |
492 | or die "Can't fork for sendmail: $!\n"; | |
493 | print SENDMAIL <<"EOF"; | |
494 | From: User Originating Mail <me\@host> | |
495 | To: Final Destination <you\@otherhost> | |
496 | Subject: A relevant subject line | |
497 | ||
65acb1b1 TC |
498 | Body of the message goes here after the blank line |
499 | in as many lines as you like. | |
c8db1d39 TC |
500 | EOF |
501 | close(SENDMAIL) or warn "sendmail didn't close nicely"; | |
502 | ||
503 | The B<-oi> option prevents sendmail from interpreting a line consisting | |
504 | of a single dot as "end of message". The B<-t> option says to use the | |
505 | headers to decide who to send the message to, and B<-odq> says to put | |
506 | the message into the queue. This last option means your message won't | |
507 | be immediately delivered, so leave it out if you want immediate | |
508 | delivery. | |
509 | ||
d92eb7b0 GS |
510 | Alternate, less convenient approaches include calling mail (sometimes |
511 | called mailx) directly or simply opening up port 25 have having an | |
512 | intimate conversation between just you and the remote SMTP daemon, | |
513 | probably sendmail. | |
514 | ||
515 | Or you might be able use the CPAN module Mail::Mailer: | |
c8db1d39 TC |
516 | |
517 | use Mail::Mailer; | |
518 | ||
519 | $mailer = Mail::Mailer->new(); | |
520 | $mailer->open({ From => $from_address, | |
521 | To => $to_address, | |
522 | Subject => $subject, | |
523 | }) | |
524 | or die "Can't open: $!\n"; | |
525 | print $mailer $body; | |
526 | $mailer->close(); | |
527 | ||
528 | The Mail::Internet module uses Net::SMTP which is less Unix-centric than | |
529 | Mail::Mailer, but less reliable. Avoid raw SMTP commands. There | |
d92eb7b0 | 530 | are many reasons to use a mail transport agent like sendmail. These |
8305e449 | 531 | include queuing, MX records, and security. |
c8db1d39 | 532 | |
575cc754 JH |
533 | =head2 How do I use MIME to make an attachment to a mail message? |
534 | ||
535 | This answer is extracted directly from the MIME::Lite documentation. | |
536 | Create a multipart message (i.e., one with attachments). | |
537 | ||
538 | use MIME::Lite; | |
539 | ||
540 | ### Create a new multipart message: | |
541 | $msg = MIME::Lite->new( | |
542 | From =>'me@myhost.com', | |
543 | To =>'you@yourhost.com', | |
544 | Cc =>'some@other.com, some@more.com', | |
545 | Subject =>'A message with 2 parts...', | |
546 | Type =>'multipart/mixed' | |
547 | ); | |
548 | ||
549 | ### Add parts (each "attach" has same arguments as "new"): | |
550 | $msg->attach(Type =>'TEXT', | |
551 | Data =>"Here's the GIF file you wanted" | |
552 | ); | |
553 | $msg->attach(Type =>'image/gif', | |
554 | Path =>'aaa000123.gif', | |
555 | Filename =>'logo.gif' | |
556 | ); | |
557 | ||
558 | $text = $msg->as_string; | |
559 | ||
560 | MIME::Lite also includes a method for sending these things. | |
561 | ||
562 | $msg->send; | |
563 | ||
197aec24 | 564 | This defaults to using L<sendmail> but can be customized to use |
575cc754 JH |
565 | SMTP via L<Net::SMTP>. |
566 | ||
c8db1d39 TC |
567 | =head2 How do I read mail? |
568 | ||
d92eb7b0 | 569 | While you could use the Mail::Folder module from CPAN (part of the |
5cd0b561 | 570 | MailFolder package) or the Mail::Internet module from CPAN (part |
a6dd486b | 571 | of the MailTools package), often a module is overkill. Here's a |
d92eb7b0 GS |
572 | mail sorter. |
573 | ||
574 | #!/usr/bin/perl | |
5cd0b561 | 575 | |
c8db1d39 TC |
576 | my(@msgs, @sub); |
577 | my $msgno = -1; | |
578 | $/ = ''; # paragraph reads | |
579 | while (<>) { | |
5cd0b561 | 580 | if (/^From /m) { |
c8db1d39 TC |
581 | /^Subject:\s*(?:Re:\s*)*(.*)/mi; |
582 | $sub[++$msgno] = lc($1) || ''; | |
583 | } | |
584 | $msgs[$msgno] .= $_; | |
d92eb7b0 | 585 | } |
c8db1d39 TC |
586 | for my $i (sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msgs)) { |
587 | print $msgs[$i]; | |
588 | } | |
589 | ||
d92eb7b0 | 590 | Or more succinctly, |
c8db1d39 TC |
591 | |
592 | #!/usr/bin/perl -n00 | |
593 | # bysub2 - awkish sort-by-subject | |
594 | BEGIN { $msgno = -1 } | |
595 | $sub[++$msgno] = (/^Subject:\s*(?:Re:\s*)*(.*)/mi)[0] if /^From/m; | |
596 | $msg[$msgno] .= $_; | |
597 | END { print @msg[ sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msg) ] } | |
598 | ||
68dc0745 | 599 | =head2 How do I find out my hostname/domainname/IP address? |
600 | ||
c8db1d39 TC |
601 | The normal way to find your own hostname is to call the C<`hostname`> |
602 | program. While sometimes expedient, this has some problems, such as | |
603 | not knowing whether you've got the canonical name or not. It's one of | |
604 | those tradeoffs of convenience versus portability. | |
68dc0745 | 605 | |
606 | The Sys::Hostname module (part of the standard perl distribution) will | |
607 | give you the hostname after which you can find out the IP address | |
608 | (assuming you have working DNS) with a gethostbyname() call. | |
609 | ||
610 | use Socket; | |
611 | use Sys::Hostname; | |
612 | my $host = hostname(); | |
65acb1b1 | 613 | my $addr = inet_ntoa(scalar gethostbyname($host || 'localhost')); |
68dc0745 | 614 | |
615 | Probably the simplest way to learn your DNS domain name is to grok | |
616 | it out of /etc/resolv.conf, at least under Unix. Of course, this | |
617 | assumes several things about your resolv.conf configuration, including | |
618 | that it exists. | |
619 | ||
620 | (We still need a good DNS domain name-learning method for non-Unix | |
621 | systems.) | |
622 | ||
623 | =head2 How do I fetch a news article or the active newsgroups? | |
624 | ||
625 | Use the Net::NNTP or News::NNTPClient modules, both available from CPAN. | |
a6dd486b | 626 | This can make tasks like fetching the newsgroup list as simple as |
68dc0745 | 627 | |
628 | perl -MNews::NNTPClient | |
629 | -e 'print News::NNTPClient->new->list("newsgroups")' | |
630 | ||
631 | =head2 How do I fetch/put an FTP file? | |
632 | ||
633 | LWP::Simple (available from CPAN) can fetch but not put. Net::FTP (also | |
634 | available from CPAN) is more complex but can put as well as fetch. | |
635 | ||
636 | =head2 How can I do RPC in Perl? | |
637 | ||
b68463f7 RGS |
638 | (Contributed by brian d foy) |
639 | ||
640 | Use one of the RPC modules you can find on CPAN ( | |
641 | http://search.cpan.org/search?query=RPC&mode=all ). | |
68dc0745 | 642 | |
643 | =head1 AUTHOR AND COPYRIGHT | |
644 | ||
7678cced RGS |
645 | Copyright (c) 1997-2005 Tom Christiansen, Nathan Torkington, and |
646 | other authors as noted. All rights reserved. | |
5a964f20 | 647 | |
5a7beb56 JH |
648 | This documentation is free; you can redistribute it and/or modify it |
649 | under the same terms as Perl itself. | |
5a964f20 TC |
650 | |
651 | Irrespective of its distribution, all code examples in this file | |
652 | are hereby placed into the public domain. You are permitted and | |
653 | encouraged to use this code in your own programs for fun | |
654 | or for profit as you see fit. A simple comment in the code giving | |
655 | credit would be courteous but is not required. |