Commit | Line | Data |
---|---|---|
68dc0745 | 1 | =head1 NAME |
2 | ||
213329dd | 3 | perlfaq9 - Networking ($Revision: 1.5 $, $Date: 2001/11/09 08:06:04 $) |
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 | ||
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 | |
18 | ||
19 | The original CGI specification is at: http://hoohoo.ncsa.uiuc.edu/cgi/ | |
20 | ||
21 | Current best-practice RFC draft at: http://CGI-Spec.Golux.Com/ | |
22 | ||
23 | Other relevant documentation listed in: http://www.perl.org/CGI_MetaFAQ.html | |
68dc0745 | 24 | |
24f1ba9b JH |
25 | These Perl FAQs very selectively cover some CGI issues. However, Perl |
26 | programmers are strongly advised to use the CGI.pm module, to take care | |
27 | of the details for them. | |
68dc0745 | 28 | |
24f1ba9b JH |
29 | The similarity between CGI response headers (defined in the CGI |
30 | specification) and HTTP response headers (defined in the HTTP | |
31 | specification, RFC2616) is intentional, but can sometimes be confusing. | |
68dc0745 | 32 | |
24f1ba9b JH |
33 | The CGI specification defines two kinds of script: the "Parsed Header" |
34 | script, and the "Non Parsed Header" (NPH) script. Check your server | |
35 | documentation to see what it supports. "Parsed Header" scripts are | |
36 | simpler in various respects. The CGI specification allows any of the | |
37 | usual newline representations in the CGI response (it's the server's | |
38 | job to create an accurate HTTP response based on it). So "\n" written in | |
39 | text mode is technically correct, and recommended. NPH scripts are more | |
40 | tricky: they must put out a complete and accurate set of HTTP | |
41 | transaction response headers; the HTTP specification calls for records | |
42 | to be terminated with carriage-return and line-feed, i.e ASCII \015\012 | |
43 | written in binary mode. | |
68dc0745 | 44 | |
24f1ba9b JH |
45 | Using CGI.pm gives excellent platform independence, including EBCDIC |
46 | systems. CGI.pm selects an appropriate newline representation | |
47 | ($CGI::CRLF) and sets binmode as appropriate. | |
c8db1d39 | 48 | |
24f1ba9b | 49 | =head2 My CGI script runs from the command line but not the browser. (500 Server Error) |
c8db1d39 | 50 | |
24f1ba9b JH |
51 | If you can demonstrate that you've read the FAQs and that |
52 | your problem isn't something simple that can be easily answered, you'll | |
53 | probably receive a courteous and useful reply to your question if you | |
54 | post it on comp.infosystems.www.authoring.cgi (if it's something to do | |
55 | with HTTP or the CGI protocols). Questions that appear to be Perl | |
56 | questions but are really CGI ones that are posted to comp.lang.perl.misc | |
57 | are not so well received. | |
c8db1d39 | 58 | |
24f1ba9b JH |
59 | The useful FAQs, related documents, and troubleshooting guides are |
60 | listed in the CGI Meta FAQ: | |
61 | ||
62 | http://www.perl.org/CGI_MetaFAQ.html | |
c8db1d39 | 63 | |
c8db1d39 TC |
64 | |
65 | =head2 How can I get better error messages from a CGI program? | |
66 | ||
67 | Use the CGI::Carp module. It replaces C<warn> and C<die>, plus the | |
68 | normal Carp modules C<carp>, C<croak>, and C<confess> functions with | |
69 | more verbose and safer versions. It still sends them to the normal | |
70 | server error log. | |
71 | ||
72 | use CGI::Carp; | |
73 | warn "This is a complaint"; | |
74 | die "But this one is serious"; | |
75 | ||
76 | The following use of CGI::Carp also redirects errors to a file of your choice, | |
77 | placed in a BEGIN block to catch compile-time warnings as well: | |
78 | ||
79 | BEGIN { | |
80 | use CGI::Carp qw(carpout); | |
81 | open(LOG, ">>/var/local/cgi-logs/mycgi-log") | |
82 | or die "Unable to append to mycgi-log: $!\n"; | |
83 | carpout(*LOG); | |
84 | } | |
85 | ||
86 | You can even arrange for fatal errors to go back to the client browser, | |
87 | which is nice for your own debugging, but might confuse the end user. | |
88 | ||
89 | use CGI::Carp qw(fatalsToBrowser); | |
90 | die "Bad error here"; | |
91 | ||
92 | Even if the error happens before you get the HTTP header out, the module | |
93 | will try to take care of this to avoid the dreaded server 500 errors. | |
94 | Normal warnings still go out to the server error log (or wherever | |
95 | you've sent them with C<carpout>) with the application name and date | |
96 | stamp prepended. | |
97 | ||
68dc0745 | 98 | =head2 How do I remove HTML from a string? |
99 | ||
f29c64d6 | 100 | The most correct way (albeit not the fastest) is to use HTML::Parser |
bed171df | 101 | from CPAN. Another mostly correct |
7d7e76cf MS |
102 | way is to use HTML::FormatText which not only removes HTML but also |
103 | attempts to do a little simple formatting of the resulting plain text. | |
68dc0745 | 104 | |
105 | Many folks attempt a simple-minded regular expression approach, like | |
c47ff5f1 | 106 | C<< s/<.*?>//g >>, but that fails in many cases because the tags |
68dc0745 | 107 | may continue over line breaks, they may contain quoted angle-brackets, |
a6dd486b JB |
108 | or HTML comment may be present. Plus, folks forget to convert |
109 | entities--like C<<> for example. | |
68dc0745 | 110 | |
111 | Here's one "simple-minded" approach, that works for most files: | |
112 | ||
113 | #!/usr/bin/perl -p0777 | |
114 | s/<(?:[^>'"]*|(['"]).*?\1)*>//gs | |
115 | ||
116 | If you want a more complete solution, see the 3-stage striphtml | |
117 | program in | |
a93751fa | 118 | http://www.cpan.org/authors/Tom_Christiansen/scripts/striphtml.gz |
68dc0745 | 119 | . |
120 | ||
c8db1d39 TC |
121 | Here are some tricky cases that you should think about when picking |
122 | a solution: | |
123 | ||
124 | <IMG SRC = "foo.gif" ALT = "A > B"> | |
125 | ||
d92eb7b0 | 126 | <IMG SRC = "foo.gif" |
c8db1d39 TC |
127 | ALT = "A > B"> |
128 | ||
129 | <!-- <A comment> --> | |
130 | ||
131 | <script>if (a<b && a>c)</script> | |
132 | ||
133 | <# Just data #> | |
134 | ||
135 | <![INCLUDE CDATA [ >>>>>>>>>>>> ]]> | |
136 | ||
137 | If HTML comments include other tags, those solutions would also break | |
138 | on text like this: | |
139 | ||
140 | <!-- This section commented out. | |
141 | <B>You can't see me!</B> | |
142 | --> | |
143 | ||
68dc0745 | 144 | =head2 How do I extract URLs? |
145 | ||
e67d034e JH |
146 | You can easily extract all sorts of URLs from HTML with |
147 | C<HTML::SimpleLinkExtor> which handles anchors, images, objects, | |
148 | frames, and many other tags that can contain a URL. If you need | |
149 | anything more complex, you can create your own subclass of | |
150 | C<HTML::LinkExtor> or C<HTML::Parser>. You might even use | |
151 | C<HTML::SimpleLinkExtor> as an example for something specifically | |
152 | suited to your needs. | |
153 | ||
154 | Less complete solutions involving regular expressions can save | |
155 | you a lot of processing time if you know that the input is simple. One | |
156 | solution from Tom Christiansen runs 100 times faster than most | |
157 | module based approaches but only extracts URLs from anchors where the first | |
158 | attribute is HREF and there are no other attributes. | |
159 | ||
160 | #!/usr/bin/perl -n00 | |
161 | # qxurl - tchrist@perl.com | |
162 | print "$2\n" while m{ | |
163 | < \s* | |
164 | A \s+ HREF \s* = \s* (["']) (.*?) \1 | |
165 | \s* > | |
166 | }gsix; | |
167 | ||
68dc0745 | 168 | |
169 | =head2 How do I download a file from the user's machine? How do I open a file on another machine? | |
170 | ||
171 | In the context of an HTML form, you can use what's known as | |
172 | B<multipart/form-data> encoding. The CGI.pm module (available from | |
173 | CPAN) supports this in the start_multipart_form() method, which isn't | |
174 | the same as the startform() method. | |
175 | ||
176 | =head2 How do I make a pop-up menu in HTML? | |
177 | ||
c47ff5f1 | 178 | Use the B<< <SELECT> >> and B<< <OPTION> >> tags. The CGI.pm |
68dc0745 | 179 | module (available from CPAN) supports this widget, as well as many |
180 | others, including some that it cleverly synthesizes on its own. | |
181 | ||
182 | =head2 How do I fetch an HTML file? | |
183 | ||
46fc3d4c | 184 | One approach, if you have the lynx text-based HTML browser installed |
185 | on your system, is this: | |
68dc0745 | 186 | |
187 | $html_code = `lynx -source $url`; | |
188 | $text_data = `lynx -dump $url`; | |
189 | ||
d92eb7b0 GS |
190 | The libwww-perl (LWP) modules from CPAN provide a more powerful way |
191 | to do this. They don't require lynx, but like lynx, can still work | |
192 | through proxies: | |
46fc3d4c | 193 | |
c8db1d39 TC |
194 | # simplest version |
195 | use LWP::Simple; | |
196 | $content = get($URL); | |
197 | ||
198 | # or print HTML from a URL | |
46fc3d4c | 199 | use LWP::Simple; |
6cecdcac | 200 | getprint "http://www.linpro.no/lwp/"; |
46fc3d4c | 201 | |
c8db1d39 | 202 | # or print ASCII from HTML from a URL |
65acb1b1 | 203 | # also need HTML-Tree package from CPAN |
46fc3d4c | 204 | use LWP::Simple; |
f29c64d6 | 205 | use HTML::Parser; |
46fc3d4c | 206 | use HTML::FormatText; |
207 | my ($html, $ascii); | |
208 | $html = get("http://www.perl.com/"); | |
209 | defined $html | |
210 | or die "Can't fetch HTML from http://www.perl.com/"; | |
211 | $ascii = HTML::FormatText->new->format(parse_html($html)); | |
212 | print $ascii; | |
213 | ||
c8db1d39 TC |
214 | =head2 How do I automate an HTML form submission? |
215 | ||
216 | If you're submitting values using the GET method, create a URL and encode | |
217 | the form using the C<query_form> method: | |
218 | ||
219 | use LWP::Simple; | |
220 | use URI::URL; | |
221 | ||
222 | my $url = url('http://www.perl.com/cgi-bin/cpan_mod'); | |
223 | $url->query_form(module => 'DB_File', readme => 1); | |
224 | $content = get($url); | |
225 | ||
226 | If you're using the POST method, create your own user agent and encode | |
227 | the content appropriately. | |
228 | ||
229 | use HTTP::Request::Common qw(POST); | |
230 | use LWP::UserAgent; | |
231 | ||
232 | $ua = LWP::UserAgent->new(); | |
233 | my $req = POST 'http://www.perl.com/cgi-bin/cpan_mod', | |
234 | [ module => 'DB_File', readme => 1 ]; | |
235 | $content = $ua->request($req)->as_string; | |
236 | ||
237 | =head2 How do I decode or create those %-encodings on the web? | |
68dc0745 | 238 | |
68dc0745 | 239 | |
575cc754 JH |
240 | If you are writing a CGI script, you should be using the CGI.pm module |
241 | that comes with perl, or some other equivalent module. The CGI module | |
242 | automatically decodes queries for you, and provides an escape() | |
243 | function to handle encoding. | |
68dc0745 | 244 | |
575cc754 JH |
245 | |
246 | The best source of detailed information on URI encoding is RFC 2396. | |
247 | Basically, the following substitutions do it: | |
248 | ||
249 | s/([^\w()'*~!.-])/sprintf '%%%02x', $1/eg; # encode | |
250 | ||
251 | s/%([A-Fa-f\d]{2})/chr hex $1/eg; # decode | |
252 | ||
253 | However, you should only apply them to individual URI components, not | |
254 | the entire URI, otherwise you'll lose information and generally mess | |
255 | things up. If that didn't explain it, don't worry. Just go read | |
256 | section 2 of the RFC, it's probably the best explanation there is. | |
257 | ||
258 | RFC 2396 also contains a lot of other useful information, including a | |
259 | regexp for breaking any arbitrary URI into components (Appendix B). | |
68dc0745 | 260 | |
261 | =head2 How do I redirect to another page? | |
262 | ||
24f1ba9b JH |
263 | Specify the complete URL of the destination (even if it is on the same |
264 | server). This is one of the two different kinds of CGI "Location:" | |
265 | responses which are defined in the CGI specification for a Parsed Headers | |
266 | script. The other kind (an absolute URLpath) is resolved internally to | |
267 | the server without any HTTP redirection. The CGI specifications do not | |
268 | allow relative URLs in either case. | |
269 | ||
270 | Use of CGI.pm is strongly recommended. This example shows redirection | |
271 | with a complete URL. This redirection is handled by the web browser. | |
272 | ||
273 | use CGI qw/:standard/; | |
274 | ||
a93751fa | 275 | my $url = 'http://www.cpan.org/'; |
24f1ba9b | 276 | print redirect($url); |
68dc0745 | 277 | |
68dc0745 | 278 | |
24f1ba9b JH |
279 | This example shows a redirection with an absolute URLpath. This |
280 | redirection is handled by the local web server. | |
68dc0745 | 281 | |
24f1ba9b JH |
282 | my $url = '/CPAN/index.html'; |
283 | print redirect($url); | |
c8db1d39 | 284 | |
d92eb7b0 | 285 | |
24f1ba9b JH |
286 | But if coded directly, it could be as follows (the final "\n" is |
287 | shown separately, for clarity), using either a complete URL or | |
288 | an absolute URLpath. | |
d92eb7b0 | 289 | |
24f1ba9b JH |
290 | print "Location: $url\n"; # CGI response header |
291 | print "\n"; # end of headers | |
d92eb7b0 | 292 | |
c8db1d39 | 293 | |
68dc0745 | 294 | =head2 How do I put a password on my web pages? |
295 | ||
296 | That depends. You'll need to read the documentation for your web | |
297 | server, or perhaps check some of the other FAQs referenced above. | |
298 | ||
299 | =head2 How do I edit my .htpasswd and .htgroup files with Perl? | |
300 | ||
301 | The HTTPD::UserAdmin and HTTPD::GroupAdmin modules provide a | |
302 | consistent OO interface to these files, regardless of how they're | |
426affbf LS |
303 | stored. Databases may be text, dbm, Berkeley DB or any database with |
304 | a DBI compatible driver. HTTPD::UserAdmin supports files used by the | |
68dc0745 | 305 | `Basic' and `Digest' authentication schemes. Here's an example: |
306 | ||
307 | use HTTPD::UserAdmin (); | |
308 | HTTPD::UserAdmin | |
309 | ->new(DB => "/foo/.htpasswd") | |
310 | ->add($username => $password); | |
311 | ||
46fc3d4c | 312 | =head2 How do I make sure users can't enter values into a form that cause my CGI script to do bad things? |
313 | ||
24f1ba9b | 314 | See the security references listed in the CGI Meta FAQ |
46fc3d4c | 315 | |
24f1ba9b | 316 | http://www.perl.org/CGI_MetaFAQ.html |
46fc3d4c | 317 | |
5a964f20 | 318 | =head2 How do I parse a mail header? |
68dc0745 | 319 | |
320 | For a quick-and-dirty solution, try this solution derived | |
b73a15ae | 321 | from L<perlfunc/split>: |
68dc0745 | 322 | |
323 | $/ = ''; | |
324 | $header = <MSG>; | |
325 | $header =~ s/\n\s+/ /g; # merge continuation lines | |
326 | %head = ( UNIX_FROM_LINE, split /^([-\w]+):\s*/m, $header ); | |
327 | ||
328 | That solution doesn't do well if, for example, you're trying to | |
329 | maintain all the Received lines. A more complete approach is to use | |
330 | the Mail::Header module from CPAN (part of the MailTools package). | |
331 | ||
332 | =head2 How do I decode a CGI form? | |
333 | ||
c8db1d39 TC |
334 | You use a standard module, probably CGI.pm. Under no circumstances |
335 | should you attempt to do so by hand! | |
336 | ||
337 | You'll see a lot of CGI programs that blindly read from STDIN the number | |
338 | of bytes equal to CONTENT_LENGTH for POSTs, or grab QUERY_STRING for | |
339 | decoding GETs. These programs are very poorly written. They only work | |
340 | sometimes. They typically forget to check the return value of the read() | |
341 | system call, which is a cardinal sin. They don't handle HEAD requests. | |
342 | They don't handle multipart forms used for file uploads. They don't deal | |
343 | with GET/POST combinations where query fields are in more than one place. | |
344 | They don't deal with keywords in the query string. | |
345 | ||
346 | In short, they're bad hacks. Resist them at all costs. Please do not be | |
347 | tempted to reinvent the wheel. Instead, use the CGI.pm or CGI_Lite.pm | |
348 | (available from CPAN), or if you're trapped in the module-free land | |
349 | of perl1 .. perl4, you might look into cgi-lib.pl (available from | |
65acb1b1 | 350 | http://cgi-lib.stanford.edu/cgi-lib/ ). |
c8db1d39 TC |
351 | |
352 | Make sure you know whether to use a GET or a POST in your form. | |
353 | GETs should only be used for something that doesn't update the server. | |
354 | Otherwise you can get mangled databases and repeated feedback mail | |
355 | messages. The fancy word for this is ``idempotency''. This simply | |
356 | means that there should be no difference between making a GET request | |
357 | for a particular URL once or multiple times. This is because the | |
358 | HTTP protocol definition says that a GET request may be cached by the | |
359 | browser, or server, or an intervening proxy. POST requests cannot be | |
360 | cached, because each request is independent and matters. Typically, | |
361 | POST requests change or depend on state on the server (query or update | |
362 | a database, send mail, or purchase a computer). | |
68dc0745 | 363 | |
5a964f20 | 364 | =head2 How do I check a valid mail address? |
68dc0745 | 365 | |
c8db1d39 | 366 | You can't, at least, not in real time. Bummer, eh? |
68dc0745 | 367 | |
c8db1d39 TC |
368 | Without sending mail to the address and seeing whether there's a human |
369 | on the other hand to answer you, you cannot determine whether a mail | |
370 | address is valid. Even if you apply the mail header standard, you | |
371 | can have problems, because there are deliverable addresses that aren't | |
372 | RFC-822 (the mail header standard) compliant, and addresses that aren't | |
373 | deliverable which are compliant. | |
68dc0745 | 374 | |
c8db1d39 | 375 | Many are tempted to try to eliminate many frequently-invalid |
d92eb7b0 | 376 | mail addresses with a simple regex, such as |
b8c8cfe2 | 377 | C</^[\w.-]+\@(?:[\w-]+\.)+\w+$/>. It's a very bad idea. However, |
c8db1d39 | 378 | this also throws out many valid ones, and says nothing about |
b8c8cfe2 | 379 | potential deliverability, so it is not suggested. Instead, see |
a93751fa | 380 | http://www.cpan.org/authors/Tom_Christiansen/scripts/ckaddr.gz, |
68dc0745 | 381 | which actually checks against the full RFC spec (except for nested |
5a964f20 | 382 | comments), looks for addresses you may not wish to accept mail to |
68dc0745 | 383 | (say, Bill Clinton or your postmaster), and then makes sure that the |
c8db1d39 TC |
384 | hostname given can be looked up in the DNS MX records. It's not fast, |
385 | but it works for what it tries to do. | |
386 | ||
387 | Our best advice for verifying a person's mail address is to have them | |
388 | enter their address twice, just as you normally do to change a password. | |
389 | This usually weeds out typos. If both versions match, send | |
390 | mail to that address with a personal message that looks somewhat like: | |
391 | ||
392 | Dear someuser@host.com, | |
393 | ||
394 | Please confirm the mail address you gave us Wed May 6 09:38:41 | |
395 | MDT 1998 by replying to this message. Include the string | |
396 | "Rumpelstiltskin" in that reply, but spelled in reverse; that is, | |
397 | start with "Nik...". Once this is done, your confirmed address will | |
398 | be entered into our records. | |
399 | ||
400 | If you get the message back and they've followed your directions, | |
401 | you can be reasonably assured that it's real. | |
68dc0745 | 402 | |
c8db1d39 TC |
403 | A related strategy that's less open to forgery is to give them a PIN |
404 | (personal ID number). Record the address and PIN (best that it be a | |
405 | random one) for later processing. In the mail you send, ask them to | |
406 | include the PIN in their reply. But if it bounces, or the message is | |
407 | included via a ``vacation'' script, it'll be there anyway. So it's | |
408 | best to ask them to mail back a slight alteration of the PIN, such as | |
409 | with the characters reversed, one added or subtracted to each digit, etc. | |
46fc3d4c | 410 | |
68dc0745 | 411 | =head2 How do I decode a MIME/BASE64 string? |
412 | ||
6a0af2f1 GA |
413 | The MIME-Base64 package (available from CPAN) handles this as well as |
414 | the MIME/QP encoding. Decoding BASE64 becomes as simple as: | |
68dc0745 | 415 | |
6a0af2f1 | 416 | use MIME::Base64; |
68dc0745 | 417 | $decoded = decode_base64($encoded); |
418 | ||
26d9b02f | 419 | The MIME-Tools package (available from CPAN) supports extraction with |
6a0af2f1 GA |
420 | decoding of BASE64 encoded attachments and content directly from email |
421 | messages. | |
422 | ||
423 | If the string to decode is short (less than 84 bytes long) | |
424 | a more direct approach is to use the unpack() function's "u" | |
68dc0745 | 425 | format after minor transliterations: |
426 | ||
427 | tr#A-Za-z0-9+/##cd; # remove non-base64 chars | |
428 | tr#A-Za-z0-9+/# -_#; # convert to uuencoded format | |
429 | $len = pack("c", 32 + 0.75*length); # compute length byte | |
430 | print unpack("u", $len . $_); # uudecode and print | |
431 | ||
5a964f20 | 432 | =head2 How do I return the user's mail address? |
68dc0745 | 433 | |
a6dd486b | 434 | On systems that support getpwuid, the $< variable, and the |
68dc0745 | 435 | Sys::Hostname module (which is part of the standard perl distribution), |
436 | you can probably try using something like this: | |
437 | ||
438 | use Sys::Hostname; | |
231ab6d1 | 439 | $address = sprintf('%s@%s', scalar getpwuid($<), hostname); |
68dc0745 | 440 | |
5a964f20 TC |
441 | Company policies on mail address can mean that this generates addresses |
442 | that the company's mail system will not accept, so you should ask for | |
443 | users' mail addresses when this matters. Furthermore, not all systems | |
68dc0745 | 444 | on which Perl runs are so forthcoming with this information as is Unix. |
445 | ||
446 | The Mail::Util module from CPAN (part of the MailTools package) provides a | |
447 | mailaddress() function that tries to guess the mail address of the user. | |
448 | It makes a more intelligent guess than the code above, using information | |
449 | given when the module was installed, but it could still be incorrect. | |
450 | Again, the best way is often just to ask the user. | |
451 | ||
c8db1d39 | 452 | =head2 How do I send mail? |
68dc0745 | 453 | |
c8db1d39 TC |
454 | Use the C<sendmail> program directly: |
455 | ||
456 | open(SENDMAIL, "|/usr/lib/sendmail -oi -t -odq") | |
457 | or die "Can't fork for sendmail: $!\n"; | |
458 | print SENDMAIL <<"EOF"; | |
459 | From: User Originating Mail <me\@host> | |
460 | To: Final Destination <you\@otherhost> | |
461 | Subject: A relevant subject line | |
462 | ||
65acb1b1 TC |
463 | Body of the message goes here after the blank line |
464 | in as many lines as you like. | |
c8db1d39 TC |
465 | EOF |
466 | close(SENDMAIL) or warn "sendmail didn't close nicely"; | |
467 | ||
468 | The B<-oi> option prevents sendmail from interpreting a line consisting | |
469 | of a single dot as "end of message". The B<-t> option says to use the | |
470 | headers to decide who to send the message to, and B<-odq> says to put | |
471 | the message into the queue. This last option means your message won't | |
472 | be immediately delivered, so leave it out if you want immediate | |
473 | delivery. | |
474 | ||
d92eb7b0 GS |
475 | Alternate, less convenient approaches include calling mail (sometimes |
476 | called mailx) directly or simply opening up port 25 have having an | |
477 | intimate conversation between just you and the remote SMTP daemon, | |
478 | probably sendmail. | |
479 | ||
480 | Or you might be able use the CPAN module Mail::Mailer: | |
c8db1d39 TC |
481 | |
482 | use Mail::Mailer; | |
483 | ||
484 | $mailer = Mail::Mailer->new(); | |
485 | $mailer->open({ From => $from_address, | |
486 | To => $to_address, | |
487 | Subject => $subject, | |
488 | }) | |
489 | or die "Can't open: $!\n"; | |
490 | print $mailer $body; | |
491 | $mailer->close(); | |
492 | ||
493 | The Mail::Internet module uses Net::SMTP which is less Unix-centric than | |
494 | Mail::Mailer, but less reliable. Avoid raw SMTP commands. There | |
d92eb7b0 | 495 | are many reasons to use a mail transport agent like sendmail. These |
8305e449 | 496 | include queuing, MX records, and security. |
c8db1d39 | 497 | |
575cc754 JH |
498 | =head2 How do I use MIME to make an attachment to a mail message? |
499 | ||
500 | This answer is extracted directly from the MIME::Lite documentation. | |
501 | Create a multipart message (i.e., one with attachments). | |
502 | ||
503 | use MIME::Lite; | |
504 | ||
505 | ### Create a new multipart message: | |
506 | $msg = MIME::Lite->new( | |
507 | From =>'me@myhost.com', | |
508 | To =>'you@yourhost.com', | |
509 | Cc =>'some@other.com, some@more.com', | |
510 | Subject =>'A message with 2 parts...', | |
511 | Type =>'multipart/mixed' | |
512 | ); | |
513 | ||
514 | ### Add parts (each "attach" has same arguments as "new"): | |
515 | $msg->attach(Type =>'TEXT', | |
516 | Data =>"Here's the GIF file you wanted" | |
517 | ); | |
518 | $msg->attach(Type =>'image/gif', | |
519 | Path =>'aaa000123.gif', | |
520 | Filename =>'logo.gif' | |
521 | ); | |
522 | ||
523 | $text = $msg->as_string; | |
524 | ||
525 | MIME::Lite also includes a method for sending these things. | |
526 | ||
527 | $msg->send; | |
528 | ||
529 | This defaults to using L<sendmail(1)> but can be customized to use | |
530 | SMTP via L<Net::SMTP>. | |
531 | ||
c8db1d39 TC |
532 | =head2 How do I read mail? |
533 | ||
d92eb7b0 GS |
534 | While you could use the Mail::Folder module from CPAN (part of the |
535 | MailFolder package) or the Mail::Internet module from CPAN (also part | |
a6dd486b | 536 | of the MailTools package), often a module is overkill. Here's a |
d92eb7b0 GS |
537 | mail sorter. |
538 | ||
539 | #!/usr/bin/perl | |
c8db1d39 TC |
540 | # bysub1 - simple sort by subject |
541 | my(@msgs, @sub); | |
542 | my $msgno = -1; | |
543 | $/ = ''; # paragraph reads | |
544 | while (<>) { | |
545 | if (/^From/m) { | |
546 | /^Subject:\s*(?:Re:\s*)*(.*)/mi; | |
547 | $sub[++$msgno] = lc($1) || ''; | |
548 | } | |
549 | $msgs[$msgno] .= $_; | |
d92eb7b0 | 550 | } |
c8db1d39 TC |
551 | for my $i (sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msgs)) { |
552 | print $msgs[$i]; | |
553 | } | |
554 | ||
d92eb7b0 | 555 | Or more succinctly, |
c8db1d39 TC |
556 | |
557 | #!/usr/bin/perl -n00 | |
558 | # bysub2 - awkish sort-by-subject | |
559 | BEGIN { $msgno = -1 } | |
560 | $sub[++$msgno] = (/^Subject:\s*(?:Re:\s*)*(.*)/mi)[0] if /^From/m; | |
561 | $msg[$msgno] .= $_; | |
562 | END { print @msg[ sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msg) ] } | |
563 | ||
68dc0745 | 564 | =head2 How do I find out my hostname/domainname/IP address? |
565 | ||
c8db1d39 TC |
566 | The normal way to find your own hostname is to call the C<`hostname`> |
567 | program. While sometimes expedient, this has some problems, such as | |
568 | not knowing whether you've got the canonical name or not. It's one of | |
569 | those tradeoffs of convenience versus portability. | |
68dc0745 | 570 | |
571 | The Sys::Hostname module (part of the standard perl distribution) will | |
572 | give you the hostname after which you can find out the IP address | |
573 | (assuming you have working DNS) with a gethostbyname() call. | |
574 | ||
575 | use Socket; | |
576 | use Sys::Hostname; | |
577 | my $host = hostname(); | |
65acb1b1 | 578 | my $addr = inet_ntoa(scalar gethostbyname($host || 'localhost')); |
68dc0745 | 579 | |
580 | Probably the simplest way to learn your DNS domain name is to grok | |
581 | it out of /etc/resolv.conf, at least under Unix. Of course, this | |
582 | assumes several things about your resolv.conf configuration, including | |
583 | that it exists. | |
584 | ||
585 | (We still need a good DNS domain name-learning method for non-Unix | |
586 | systems.) | |
587 | ||
588 | =head2 How do I fetch a news article or the active newsgroups? | |
589 | ||
590 | Use the Net::NNTP or News::NNTPClient modules, both available from CPAN. | |
a6dd486b | 591 | This can make tasks like fetching the newsgroup list as simple as |
68dc0745 | 592 | |
593 | perl -MNews::NNTPClient | |
594 | -e 'print News::NNTPClient->new->list("newsgroups")' | |
595 | ||
596 | =head2 How do I fetch/put an FTP file? | |
597 | ||
598 | LWP::Simple (available from CPAN) can fetch but not put. Net::FTP (also | |
599 | available from CPAN) is more complex but can put as well as fetch. | |
600 | ||
601 | =head2 How can I do RPC in Perl? | |
602 | ||
a6dd486b | 603 | A DCE::RPC module is being developed (but is not yet available) and |
68dc0745 | 604 | will be released as part of the DCE-Perl package (available from |
65acb1b1 TC |
605 | CPAN). The rpcgen suite, available from CPAN/authors/id/JAKE/, is |
606 | an RPC stub generator and includes an RPC::ONC module. | |
68dc0745 | 607 | |
608 | =head1 AUTHOR AND COPYRIGHT | |
609 | ||
65acb1b1 | 610 | Copyright (c) 1997-1999 Tom Christiansen and Nathan Torkington. |
5a964f20 TC |
611 | All rights reserved. |
612 | ||
5a7beb56 JH |
613 | This documentation is free; you can redistribute it and/or modify it |
614 | under the same terms as Perl itself. | |
5a964f20 TC |
615 | |
616 | Irrespective of its distribution, all code examples in this file | |
617 | are hereby placed into the public domain. You are permitted and | |
618 | encouraged to use this code in your own programs for fun | |
619 | or for profit as you see fit. A simple comment in the code giving | |
620 | credit would be courteous but is not required. |