1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
|
package LWP::Protocol;
require LWP::MemberMixin;
@ISA = qw(LWP::MemberMixin);
$VERSION = "6.06";
use strict;
use Carp ();
use HTTP::Status ();
use HTTP::Response;
my %ImplementedBy = (); # scheme => classname
sub new
{
my($class, $scheme, $ua) = @_;
my $self = bless {
scheme => $scheme,
ua => $ua,
# historical/redundant
max_size => $ua->{max_size},
}, $class;
$self;
}
sub create
{
my($scheme, $ua) = @_;
my $impclass = LWP::Protocol::implementor($scheme) or
Carp::croak("Protocol scheme '$scheme' is not supported");
# hand-off to scheme specific implementation sub-class
my $protocol = $impclass->new($scheme, $ua);
return $protocol;
}
sub implementor
{
my($scheme, $impclass) = @_;
if ($impclass) {
$ImplementedBy{$scheme} = $impclass;
}
my $ic = $ImplementedBy{$scheme};
return $ic if $ic;
return '' unless $scheme =~ /^([.+\-\w]+)$/; # check valid URL schemes
$scheme = $1; # untaint
$scheme =~ s/[.+\-]/_/g; # make it a legal module name
# scheme not yet known, look for a 'use'd implementation
$ic = "LWP::Protocol::$scheme"; # default location
$ic = "LWP::Protocol::nntp" if $scheme eq 'news'; #XXX ugly hack
no strict 'refs';
# check we actually have one for the scheme:
unless (@{"${ic}::ISA"}) {
# try to autoload it
eval "require $ic";
if ($@) {
if ($@ =~ /Can't locate/) { #' #emacs get confused by '
$ic = '';
}
else {
die "$@\n";
}
}
}
$ImplementedBy{$scheme} = $ic if $ic;
$ic;
}
sub request
{
my($self, $request, $proxy, $arg, $size, $timeout) = @_;
Carp::croak('LWP::Protocol::request() needs to be overridden in subclasses');
}
# legacy
sub timeout { shift->_elem('timeout', @_); }
sub max_size { shift->_elem('max_size', @_); }
sub collect
{
my ($self, $arg, $response, $collector) = @_;
my $content;
my($ua, $max_size) = @{$self}{qw(ua max_size)};
eval {
local $\; # protect the print below from surprises
if (!defined($arg) || !$response->is_success) {
$response->{default_add_content} = 1;
}
elsif (!ref($arg) && length($arg)) {
open(my $fh, ">", $arg) or die "Can't write to '$arg': $!";
binmode($fh);
push(@{$response->{handlers}{response_data}}, {
callback => sub {
print $fh $_[3] or die "Can't write to '$arg': $!";
1;
},
});
push(@{$response->{handlers}{response_done}}, {
callback => sub {
close($fh) or die "Can't write to '$arg': $!";
undef($fh);
},
});
}
elsif (ref($arg) eq 'CODE') {
push(@{$response->{handlers}{response_data}}, {
callback => sub {
&$arg($_[3], $_[0], $self);
1;
},
});
}
else {
die "Unexpected collect argument '$arg'";
}
$ua->run_handlers("response_header", $response);
if (delete $response->{default_add_content}) {
push(@{$response->{handlers}{response_data}}, {
callback => sub {
$_[0]->add_content($_[3]);
1;
},
});
}
my $content_size = 0;
my $length = $response->content_length;
my %skip_h;
while ($content = &$collector, length $$content) {
for my $h ($ua->handlers("response_data", $response)) {
next if $skip_h{$h};
unless ($h->{callback}->($response, $ua, $h, $$content)) {
# XXX remove from $response->{handlers}{response_data} if present
$skip_h{$h}++;
}
}
$content_size += length($$content);
$ua->progress(($length ? ($content_size / $length) : "tick"), $response);
if (defined($max_size) && $content_size > $max_size) {
$response->push_header("Client-Aborted", "max_size");
last;
}
}
};
my $err = $@;
delete $response->{handlers}{response_data};
delete $response->{handlers} unless %{$response->{handlers}};
if ($err) {
chomp($err);
$response->push_header('X-Died' => $err);
$response->push_header("Client-Aborted", "die");
return $response;
}
return $response;
}
sub collect_once
{
my($self, $arg, $response) = @_;
my $content = \ $_[3];
my $first = 1;
$self->collect($arg, $response, sub {
return $content if $first--;
return \ "";
});
}
1;
__END__
=head1 NAME
LWP::Protocol - Base class for LWP protocols
=head1 SYNOPSIS
package LWP::Protocol::foo;
require LWP::Protocol;
@ISA=qw(LWP::Protocol);
=head1 DESCRIPTION
This class is used a the base class for all protocol implementations
supported by the LWP library.
When creating an instance of this class using
C<LWP::Protocol::create($url)>, and you get an initialized subclass
appropriate for that access method. In other words, the
LWP::Protocol::create() function calls the constructor for one of its
subclasses.
All derived LWP::Protocol classes need to override the request()
method which is used to service a request. The overridden method can
make use of the collect() function to collect together chunks of data
as it is received.
The following methods and functions are provided:
=over 4
=item $prot = LWP::Protocol->new()
The LWP::Protocol constructor is inherited by subclasses. As this is a
virtual base class this method should B<not> be called directly.
=item $prot = LWP::Protocol::create($scheme)
Create an object of the class implementing the protocol to handle the
given scheme. This is a function, not a method. It is more an object
factory than a constructor. This is the function user agents should
use to access protocols.
=item $class = LWP::Protocol::implementor($scheme, [$class])
Get and/or set implementor class for a scheme. Returns '' if the
specified scheme is not supported.
=item $prot->request(...)
$response = $protocol->request($request, $proxy, undef);
$response = $protocol->request($request, $proxy, '/tmp/sss');
$response = $protocol->request($request, $proxy, \&callback, 1024);
Dispatches a request over the protocol, and returns a response
object. This method needs to be overridden in subclasses. Refer to
L<LWP::UserAgent> for description of the arguments.
=item $prot->collect($arg, $response, $collector)
Called to collect the content of a request, and process it
appropriately into a scalar, file, or by calling a callback. If $arg
is undefined, then the content is stored within the $response. If
$arg is a simple scalar, then $arg is interpreted as a file name and
the content is written to this file. If $arg is a reference to a
routine, then content is passed to this routine.
The $collector is a routine that will be called and which is
responsible for returning pieces (as ref to scalar) of the content to
process. The $collector signals EOF by returning a reference to an
empty string.
The return value from collect() is the $response object reference.
B<Note:> We will only use the callback or file argument if
$response->is_success(). This avoids sending content data for
redirects and authentication responses to the callback which would be
confusing.
=item $prot->collect_once($arg, $response, $content)
Can be called when the whole response content is available as
$content. This will invoke collect() with a collector callback that
returns a reference to $content the first time and an empty string the
next.
=back
=head1 SEE ALSO
Inspect the F<LWP/Protocol/file.pm> and F<LWP/Protocol/http.pm> files
for examples of usage.
=head1 COPYRIGHT
Copyright 1995-2001 Gisle Aas.
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
|