1HTTP::Proxy(3) User Contributed Perl Documentation HTTP::Proxy(3)
2
6 HTTP::Proxy - A pure Perl HTTP proxy
7
9 use HTTP::Proxy;
10 # initialisation
12 my $proxy = HTTP::Proxy->new( port => 3128 );
13 # alternate initialisation
15 my $proxy = HTTP::Proxy->new;
16 $proxy->port( 3128 ); # the classical accessors are here!
17 # this is a MainLoop-like method
19 $proxy->start;
20
22 This module implements a HTTP proxy, using a HTTP::Daemon to accept
23 client connections, and a LWP::UserAgent to ask for the requested
24 pages.
25 The most interesting feature of this proxy object is its ability to
27 filter the HTTP requests and responses through user-defined filters.
28 Once the proxy is created, with the "new()" method, it is possible to
30 alter its behaviour by adding so-called "filters". This is done by the
31 "push_filter()" method. Once the filter is ready to run, it can be
32 launched, with the "start()" method. This method does not normally
33 return until the proxy is killed or otherwise stopped.
34 An important thing to note is that the proxy is (except when running
36 the "NoFork" engine) a forking proxy: it doesn't support passing infor‐
37 mation between child processes, and you can count on reliable informa‐
38 tion passing only during a single HTTP connection (request + response).
39
41 You can alter the way the default HTTP::Proxy works by plugging call‐
42 backs (filter objects, actually) at different stages of the
43 request/response handling.
44 When a request is received by the HTTP::Proxy object, it is filtered
46 through a standard filter that transform this request accordingly to
47 RFC 2616 (by adding the "Via:" header, and a few other transforma‐
48 tions). This is the default, bare minimum behaviour.
49 The response is also filtered in the same manner. There is a total of
51 four filter chains: "request-headers", "request-body", "reponse-head‐
52 ers" and "response-body".
53 You can add your own filters to the default ones with the "push_fil‐
55 ter()" method. The method pushes a filter on the appropriate filter
56 stack.
57 $proxy->push_filter( response => $filter );
59 The headers/body category is determined by the base class of the fil‐
61 ter. There are two base classes for filters, which are
62 "HTTP::Proxy::HeaderFilter" and "HTTP::Proxy::BodyFilter" (the names
63 are self-explanatory). See the documentation of those two classes to
64 find out how to write your own header or body filters.
65 The named parameter is used to determine the request/response part.
67 It is possible to push the same filter on the request and response
69 stacks, as in the following example:
70 $proxy->push_filter( request => $filter, response => $filter );
72 If several filters match the message, they will be applied in the order
74 they were pushed on their filter stack.
75 Named parameters can be used to create the match routine. They are:
77 method - the request method
79 scheme - the URI scheme
80 host - the URI authority (host:port)
81 path - the URI path
82 query - the URI query string
83 mime - the MIME type (for a response-body filter)
84 The filters are applied only when all the the parameters match the
86 request or the response. All these named parameters have default val‐
87 ues, which are:
88 method => 'OPTIONS,GET,HEAD,POST,PUT,DELETE,TRACE,CONNECT'
90 scheme => 'http'
91 host => ''
92 path => ''
93 query => ''
94 mime => 'text/*'
95 The "mime" parameter is a glob-like string, with a required "/" charac‐
97 ter and a "*" as a joker. Thus, "*/*" matches all responses, and ""
98 those with no "Content-Type:" header. To match any reponse (with or
99 without a "Content-Type:" header), use "undef".
100 The "mime" parameter is only meaningful with the "response-body" filter
102 stack. It is ignored if passed to any other filter stack.
103 The "method" and "scheme" parameters are strings consisting of comma-
105 separated values. The "host" and "path" parameters are regular expres‐
106 sions.
107 A match routine is compiled by the proxy and used to check if a partic‐
109 ular request or response must be filtered through a particular filter.
110 It is also possible to push several filters on the same stack with the
112 same match subroutine:
113 # convert italics to bold
115 $proxy->push_filter(
116 mime => 'text/html',
117 response => HTTP::Proxy::BodyFilter::tags->new(),
118 response =>
119 HTTP::Proxy::BodyFilter::simple->new( sub { s!(</?)i>!$1b>!ig } )
120 );
121 For more details regarding the creation of new filters, check the
123 "HTTP::Proxy::HeaderFilter" and "HTTP::Proxy::BodyFilter" documenta‐
124 tion.
125 Here's an example of subclassing a base filter class:
127 # fixes a common typo ;-)
129 # but chances are that this will modify a correct URL
130 {
131 package FilterPerl;
132 use base qw( HTTP::Proxy::BodyFilter );
133 sub filter {
135 my ( $self, $dataref, $message, $protocol, $buffer ) = @_;
136 $$dataref =~ s/PERL/Perl/g;
137 }
138 }
139 $proxy->push_filter( response => FilterPerl->new() );
140 Other examples can be found in the documentation for
142 "HTTP::Proxy::HeaderFilter", "HTTP::Proxy::BodyFilter",
143 "HTTP::Proxy::HeaderFilter::simple", "HTTP::Proxy::BodyFilter::simple".
144 # a simple anonymiser
146 # see eg/anonymiser.pl for the complete code
147 $proxy->push_filter(
148 mime => undef,
149 request => HTTP::Proxy::HeaderFilter::simple->new(
150 sub { $_[0]->remove_header(qw( User-Agent From Referer Cookie )) },
151 ),
152 response => HTTP::Proxy::HeaderFilter::simple->new(
153 sub { $_[0]->remove_header(qw( Set-Cookie )); },
154 )
155 );
156 IMPORTANT: If you use your own "LWP::UserAgent", you must install it
158 before your calls to "push_filter()", otherwise the match method will
159 make wrong assumptions about the schemes your agent supports.
160 NOTE: It is likely that possibility of changing the agent or the daemon
162 may disappear in future versions.
163
165 Constructor and initialisation
166 new()
168 The "new()" method creates a new HTTP::Proxy object. All attributes
169 can be passed as parameters to replace the default.
170 Parameters that are not "HTTP::Proxy" attributes will be ignored
172 and passed to the chosen "HTTP::Proxy::Engine" object.
173 init()
175 "init()" initialise the proxy without starting it. It is usually
176 not needed.
177 This method is called by "start()" if needed.
179 push_filter()
181 The "push_filter()" method is used to add filters to the proxy. It
182 is fully described in section FILTERS.
183 Accessors and mutators
185 The HTTP::Proxy has several accessors and mutators.
187 Called with arguments, the accessor returns the current value. Called
189 with a single argument, it sets the current value and returns the pre‐
190 vious one, in case you want to keep it.
191 If you call a read-only accessor with a parameter, this parameter will
193 be ignored.
194 The defined accessors are (in alphabetical order):
196 agent
198 The LWP::UserAgent object used internally to connect to remote
199 sites.
200 chunk
202 The chunk size for the LWP::UserAgent callbacks.
203 client_socket (read-only)
205 The socket currently connected to the client. Mostly useful in fil‐
206 ters.
207 client_headers
209 This attribute holds a reference to the client headers set up by
210 LWP::UserAgent ("Client-Aborted", "Client-Bad-Header-Line",
211 "Client-Date", "Client-Junk", "Client-Peer", "Client-Request-Num",
212 "Client-Response-Num", "Client-SSL-Cert-Issuer",
213 "Client-SSL-Cert-Subject", "Client-SSL-Cipher", "Client-SSL-Warn‐
214 ing", "Client-Transfer-Encoding", "Client-Warning").
215 They are removed by the filter HTTP::Proxy::HeaderFilter::standard
217 from the request and response objects received by the proxy.
218 If a filter (such as a SSL certificate verification filter) need to
220 access them, it must do it through this accessor.
221 conn (read-only)
223 The number of connections processed by this HTTP::Proxy instance.
224 daemon
226 The HTTP::Daemon object used to accept incoming connections. (You
227 usually never need this.)
228 engine
230 The HTTP::Proxy::Engine object that manages the child processes.
231 hop_headers
233 This attribute holds a reference to the hop-by-hop headers ("Con‐
234 nection", "Keep-Alive", "Proxy-Authenticate", "Proxy-Authoriza‐
235 tion", "TE", "Trailers", "Transfer-Encoding", "Upgrade").
236 They are removed by the filter HTTP::Proxy::HeaderFilter::standard
238 from the request and response objects received by the proxy.
239 If a filter (such as a proxy authorisation filter) need to access
241 them, it must do it through this accessor.
242 host
244 The proxy HTTP::Daemon host (default: 'localhost').
245 This means that by default, the proxy answers only to clients on
247 the local machine. You can pass a specific interface address or
248 ""/"undef" for any interface.
249 This default prevents your proxy to be used as an anonymous proxy
251 by script kiddies.
252 known_methods( @groups ) (read-only)
254 This method returns all HTTP (and extensions to HTTP) known to
255 "HTTP::Proxy". Methods are grouped by type. Known method groups
256 are: "HTTP", "WebDAV" and "DeltaV".
257 Called with an empty list, this method will return all known meth‐
259 ods. This method is case-insensitive, and will "carp()" if an
260 unknown group name is passed.
261 logfh
263 A filehandle to a logfile (default: *STDERR).
264 logmask( [$mask] )
266 Be verbose in the logs (default: NONE).
267 Here are the various elements that can be added to the mask (their
269 values are powers of 2, starting from 0 and listed here in ascend‐
270 ing order):
271 NONE - Log only errors
273 PROXY - Proxy information
274 STATUS - Requested URL, reponse status and total number
275 of connections processed
276 PROCESS - Subprocesses information (fork, wait, etc.)
277 SOCKET - Information about low-level sockets
278 HEADERS - Full request and response headers are sent along
279 FILTERS - Filter information
280 DATA - Data received by the filters
281 CONNECT - Data transmitted by the CONNECT method
282 ENGINE - Engine information
283 ALL - Log all of the above
284 If you only want status and process information, you can use:
286 $proxy->logmask( STATUS ⎪ PROCESS );
288 Note that all the logging constants are not exported by default,
290 but by the ":log" tag. They can also be exported one by one.
291 loop (read-only)
293 Internal. False when the main loop is about to be broken.
294 max_clients
296 maxchild
297 The maximum number of child process the HTTP::Proxy object will
298 spawn to handle client requests (default: depends on the engine).
299 This method is currently delegated to the HTTP::Proxy::Engine
301 object.
302 "maxchild" is deprecated and will disappear.
304 max_connections
306 maxconn
307 The maximum number of TCP connections the proxy will accept before
308 returning from start(). 0 (the default) means never stop accepting
309 connections.
310 "maxconn" is deprecated.
312 Note: "max_connections" will be deprecated soon, for two reasons:
314 1) it is more of an HTTP::Proxy::Engine attribute, 2) not all
315 engines will support it.
316 max_keep_alive_requests
318 maxserve
319 The maximum number of requests the proxy will serve in a single
320 connection. (same as "MaxRequestsPerChild" in Apache)
321 "maxserve" is deprecated.
323 port
325 The proxy "HTTP::Daemon" port (default: 8080).
326 request
328 The request originaly received by the proxy from the user-agent,
329 which will be modified by the request filters.
330 response
332 The response received from the origin server by the proxy. It is
333 normally "undef" until the proxy actually receives the beginning of
334 a response from the origin server.
335 If one of the request filters sets this attribute, it "short-cir‐
337 cuits" the request/response scheme, and the proxy will return this
338 response (which is NOT filtered through the response filter stacks)
339 instead of the expected origin server response. This is useful for
340 caching (though Squid does it much better) and proxy authentica‐
341 tion, for example.
342 stash
344 The stash is a hash where filters can store data to share between
345 them.
346 The stash() method can be used to set the whole hash (with a HASH
348 reference). To access individual keys simply do:
349 $proxy->stash( 'bloop' );
351 To set it, type:
353 $proxy->stash( bloop => 'owww' );
355 It's also possibly to get a reference to the stash:
357 my $s = $filter->proxy->stash();
359 $s->{bang} = 'bam';
360 # $proxy->stash( 'bang' ) will now return 'bam'
362 Warning: since the proxy forks for each TCP connection, the data is
364 only shared between filters in the same child process.
365 timeout
367 The timeout used by the internal LWP::UserAgent (default: 60).
368 url (read-only)
370 The url where the proxy can be reached.
371 via The content of the Via: header. Setting it to an empty string will
373 prevent its addition. (default: "$hostname (HTTP::Proxy/$VERSION)")
374 x_forwarded_for
376 If set to a true value, the proxy will send the "X-Forwarded-For:"
377 header. (default: true)
378 Connection handling methods
380 start()
382 This method works like Tk's "MainLoop": you hand over control to
383 the "HTTP::Proxy" object you created and configured.
384 If "maxconn" is not zero, "start()" will return after accepting at
386 most that many connections. It will return the total number of con‐
387 nexions.
388 serve_connections()
390 This is the internal method used to handle each new TCP connection
391 to the proxy.
392 Other methods
394 log( $level, $prefix, $message )
396 Adds $message at the end of "logfh", if $level matches "logmask".
397 The "log()" method also prints a timestamp.
398 The output looks like:
400 [Thu Dec 5 12:30:12 2002] ($$) $prefix: $message
402 where $$ is the current processus id.
404 If $message is a multiline string, several log lines will be out‐
406 put, each line starting with $prefix.
407 is_protocol_supported( $scheme )
409 Returns a boolean indicating if $scheme is supported by the proxy.
410 This method is only used internaly.
412 It is essential to allow HTTP::Proxy users to create
414 "pseudo-schemes" that LWP doesn't know about, but that one of the
415 proxy filters can handle directly. New schemes are added as fol‐
416 lows:
417 $proxy->init(); # required to get an agent
419 $proxy->agent->protocols_allowed(
420 [ @{ $proxy->agent->protocols_allowed }, 'myhttp' ] );
421 new_connection()
423 Increase the proxy's TCP connections counter. Only used by
424 "HTTP::Proxy::Engine" objects.
425 Apache-like attributes
427 "HTTP::Proxy" has several Apache-like attributes that control the way
429 the HTTP and TCP connections are handled.
430 The following attributes control the TCP connection. They are passed to
432 the underlying "HTTP::Proxy::Engine", which may (or may not) use them
433 to change its behaviour.
434 start_servers
436 Number of child process to fork at the beginning.
437 max_clients
439 Maximum number of concurrent TCP connections (i.e. child pro‐
440 cesses).
441 max_requests_per_child
443 Maximum number of TCP connections handled by the same child
444 process.
445 min_spare_servers
447 Minimum number of inactive child processes.
448 max_spare_servers
450 Maximum number of inactive child processes.
451 Those attributes control the HTTP connection:
453 keep_alive
455 Support for keep alive HTTP connections.
456 max_keep_alive_requests
458 Maximum number of HTTP connections within a single TCP connection.
459 keep_alive_timeout
461 Timeout for keep-alive connection.
462
464 No symbols are exported by default. The ":log" tag exports all the log‐
465 ging constants.
466
468 This module does not work under Windows, but I can't see why, and do
469 not have a development platform under that system. Patches and explana‐
470 tions very welcome.
471 I guess it is because "fork()" is not well supported.
473 $proxy->maxchild(0);
475 However, David Fishburn says:
477 This did not work for me under WinXP - ActiveState Perl 5.6, but it
478 DOES work on WinXP ActiveState Perl 5.8.
479 Several people have tried to help, but we haven't found a way to make
481 it work correctly yet.
482 As from version 0.16, the default engine is
484 "HTTP::Proxy::Engine::NoFork". Let me know if it works better.
485
487 HTTP::Proxy::Engine, HTTP::Proxy::BodyFilter, HTTP::Proxy::HeaderFil‐
488 ter, the examples in eg/.
489
491 Philippe "BooK" Bruhat, <book@cpan.org>.
492 The module has its own web page at <http://http-proxy.mongueurs.net/>
494 complete with older versions and repository snapshot.
495 There are also two mailing-lists: http-proxy@mongueurs.net for general
497 discussion about "HTTP::Proxy" and http-proxy-cvs@mongueurs.net for CVS
498 commits emails.
499
501 Many people helped me during the development of this module, either on
502 mailing-lists, IRC or over a beer in a pub...
503 So, in no particular order, thanks to the libwww-perl team for such a
505 terrific suite of modules, perl-qa (tips for testing), the French Perl
506 Mongueurs (for code tricks, beers and encouragements) and my growing
507 user base... ";-)"
508 I'd like to particularly thank Dan Grigsby, who's been using
510 "HTTP::Proxy" since 2003 (before the filter classes even existed). He
511 is apparently making a living from a product based on "HTTP::Proxy".
512 Thanks a lot for your confidence in my work!
513
515 Copyright 2002-2005, Philippe Bruhat.
516
518 This module is free software; you can redistribute it or modify it
519 under the same terms as Perl itself.
520perl v5.8.8 2006-09-04 HTTP::Proxy(3)