LWP::UserAgent - Web user agent class
use strict; use warnings; use LWP::UserAgent (); my $ua = LWP::UserAgent->new(timeout => 10); $ua->env_proxy; my $response = $ua->get(http://example.com); if ($response->is_success) { print $response->decoded_content; } else { die $response->status_line; }
Extra layers of security (note the cookie_jar and
protocols_allowed):
use strict; use warnings; use HTTP::CookieJar::LWP (); use LWP::UserAgent (); my $jar = HTTP::CookieJar::LWP->new; my $ua = LWP::UserAgent->new( cookie_jar => $jar, protocols_allowed => [http, https], timeout => 10, ); $ua->env_proxy; my $response = $ua->get(http://example.com); if ($response->is_success) { print $response->decoded_content; } else { die $response->status_line; }
The LWP::UserAgent is a class implementing a web user agent. LWP::UserAgent objects can be used to dispatch web requests.
In normal use the application creates an LWP::UserAgent object, and then configures it with values for timeouts, proxies, name, etc. It then creates an instance of HTTP::Request for the request that needs to be performed. This request is then passed to one of the request method the UserAgent, which dispatches it using the relevant protocol, and returns a HTTP::Response object. There are convenience methods for sending the most common request types: get in LWP::UserAgent, head in LWP::UserAgent, post in LWP::UserAgent, put in LWP::UserAgent and delete in LWP::UserAgent. When using these methods, the creation of the request object is hidden as shown in the synopsis above.
The basic approach of the library is to use HTTP-style communication for all protocol schemes. This means that you will construct HTTP::Request objects and receive HTTP::Response objects even for non-HTTP resources like gopher and ftp. In order to achieve even more similarity to HTTP-style communications, gopher menus and file directories are converted to HTML documents.
The following constructor methods are available:
my $ua2 = $ua->clone;
Returns a copy of the LWP::UserAgent object.
CAVEAT: Please be aware that the clone method does
not copy or clone your cookie_jar attribute. Due to the
limited restrictions on what can be used for your cookie jar, there is
no way to clone the attribute. The cookie_jar attribute
will be undef in the new object instance.
my $ua = LWP::UserAgent->new( %options )
This method constructs a new LWP::UserAgent object and returns it. Key/value pair arguments may be provided to set up the initial state. The following options correspond to attribute methods described below:
KEY DEFAULT ----------- -------------------- agent "libwww-perl/#.###" conn_cache undef cookie_jar undef default_headers HTTP::Headers->new from undef local_address undef max_redirect 7 max_size undef no_proxy [] parse_head 1 protocols_allowed undef protocols_forbidden undef proxy undef requests_redirectable [GET, HEAD] ssl_opts { verify_hostname => 1 } timeout 180
The following additional options are also accepted: If the
env_proxy option is passed in with a true value, then proxy
settings are read from environment variables (see env_proxy in
LWP::UserAgent). If env_proxy isn't provided, the
PERL_LWP_ENV_PROXY environment variable controls if
env_proxy in LWP::UserAgent is called during initialization. If the
keep_alive option value is defined and non-zero, then an
LWP::ConnCache is set up (see conn_cache in
LWP::UserAgent). The keep_alive value is passed on as the
total_capacity for the connection cache.
proxy must be set as an arrayref of key/value pairs.
no_proxy takes an arrayref of domains.
The settings of the configuration attributes modify the behaviour of the LWP::UserAgent when it dispatches requests. Most of these can also be initialized by options passed to the constructor method.
The following attribute methods are provided. The attribute value is left unchanged if no argument is given. The return value from each method is the old attribute value.
my $agent = $ua->agent; $ua->agent(Checkbot/0.4 ); # append the default to the end $ua->agent(Mozilla/5.0); $ua->agent(""); # dont identify
Get/set the product token that is used to identify the user agent on
the network. The agent value is sent as the User-Agent
header in the requests.
The default is a string of the form libwww-perl/#.###,
where #.### is substituted with the version number of this
library.
If the provided string ends with space, the default
libwww-perl/#.### string is appended to it.
The user agent string should be one or more simple product
identifiers with an optional version number separated by the
/ character.
my $cache_obj = $ua->conn_cache; $ua->conn_cache( $cache_obj );
Get/set the LWP::ConnCache object to use. See LWP::ConnCache for details.
my $jar = $ua->cookie_jar; $ua->cookie_jar( $cookie_jar_obj );
Get/set the cookie jar object to use. The only requirement is that
the cookie jar object must implement the
extract_cookies($response) and
add_cookie_header($request) methods. These methods will
then be invoked by the user agent as requests are sent and responses are
received. Normally this will be a HTTP::Cookies object or some subclass.
You are, however, encouraged to use HTTP::CookieJar::LWP instead. See
BEST PRACTICES for more information.
use HTTP::CookieJar::LWP (); my $jar = HTTP::CookieJar::LWP->new; my $ua = LWP::UserAgent->new( cookie_jar => $jar ); # or after object creation $ua->cookie_jar( $cookie_jar );
The default is to have no cookie jar, i.e. never automatically add
Cookie headers to the requests.
Shortcut: If a reference to a plain hash is passed in, it is replaced with an instance of HTTP::Cookies that is initialized based on the hash. This form also automatically loads the HTTP::Cookies module. It means that:
$ua->cookie_jar({ file => "$ENV{HOME}/.cookies.txt" });
is really just a shortcut for:
require HTTP::Cookies; $ua->cookie_jar(HTTP::Cookies->new(file => "$ENV{HOME}/.cookies.txt"));
my $creds = $ua->credentials(); $ua->credentials( $netloc, $realm ); $ua->credentials( $netloc, $realm, $uname, $pass ); $ua->credentials("www.example.com:80", "Some Realm", "foo", "secret");
Get/set the user name and password to be used for a realm.
The $netloc is a string of the form
<host>:<port>. The username and password will
only be passed to this server.
$ua->default_header( $field ); $ua->default_header( $field => $value ); $ua->default_header(Accept-Encoding => scalar HTTP::Message::decodable()); $ua->default_header(Accept-Language => "no, en");
This is just a shortcut for
$ua->default_headers->header( $field => $value ).
my $headers = $ua->default_headers; $ua->default_headers( $headers_obj );
Get/set the headers object that will provide default header values for any requests sent. By default this will be an empty HTTP::Headers object.
my $from = $ua->from; $ua->from(foo@bar.com);
Get/set the email address for the human user who controls the
requesting user agent. The address should be machine-usable, as defined
in RFC2822 <https://tools.ietf.org/html/rfc2822>. The
from value is sent as the From header in the
requests.
The default is to not send a From header. See
default_headers in LWP::UserAgent for the more general interface that
allow any header to be defaulted.
my $address = $ua->local_address; $ua->local_address( $address );
Get/set the local interface to bind to for network connections. The
interface can be specified as a hostname or an IP address. This value is
passed as the LocalAddr argument to IO::Socket::INET.
my $max = $ua->max_redirect; $ua->max_redirect( $n );
This reads or sets the object's limit of how many times it will obey redirection responses in a given request cycle.
By default, the value is 7. This means that if you call
request in LWP::UserAgent and the response is a redirect elsewhere which
is in turn a redirect, and so on seven times, then LWP gives up after
that seventh request.
my $size = $ua->max_size; $ua->max_size( $bytes );
Get/set the size limit for response content. The default is
undef, which means that there is no limit. If the returned
response content is only partial, because the size limit was exceeded,
then a Client-Aborted header will be added to the response.
The content might end up longer than max_size as we abort
once appending a chunk of data makes the length exceed the limit. The
Content-Length header, if present, will indicate the length
of the full content and will normally not be the same as
length($res->content).
my $bool = $ua->parse_head; $ua->parse_head( $boolean );
Get/set a value indicating whether we should initialize response headers from the <head> section of HTML documents. The default is true. Do not turn this off unless you know what you are doing.
my $aref = $ua->protocols_allowed; # get allowed protocols $ua->protocols_allowed( \@protocols ); # allow ONLY these $ua->protocols_allowed(undef); # delete the list $ua->protocols_allowed([http,]); # ONLY allow http
By default, an object has neither a protocols_allowed
list, nor a protocols_forbidden in LWP::UserAgent list.
This reads (or sets) this user agent's list of protocols that the request methods will exclusively allow. The protocol names are case insensitive.
For example:
$ua->protocols_allowed( [ http, https] ); means that
this user agent will allow only those protocols, and attempts
to use this user agent to access URLs with any other schemes (like
ftp://...) will result in a 500 error.
Note that having a protocols_allowed list causes any
protocols_forbidden in LWP::UserAgent list to be ignored.
my $aref = $ua->protocols_forbidden; # get the forbidden list $ua->protocols_forbidden(\@protocols); # do not allow these $ua->protocols_forbidden([http,]); # All http reqs get a 500 $ua->protocols_forbidden(undef); # delete the list
This reads (or sets) this user agent's list of protocols that the request method will not allow. The protocol names are case insensitive.
For example:
$ua->protocols_forbidden( [ file, mailto] ); means that
this user agent will not allow those protocols, and attempts to
use this user agent to access URLs with those schemes will result in a
500 error.
my $aref = $ua->requests_redirectable; $ua->requests_redirectable( \@requests ); $ua->requests_redirectable([GET, HEAD,]); # the default
This reads or sets the object's list of request names that
redirect_ok in LWP::UserAgent will allow redirection for. By default,
this is [GET, HEAD], as per RFC 2616
<https://tools.ietf.org/html/rfc2616>. To change to include
POST, consider:
push @{ $ua->requests_redirectable }, POST;
my $bool = $ua->send_te; $ua->send_te( $boolean );
If true, will send a TE header along with the request.
The default is true. Set it to false to disable the TE
header for systems who can't handle it.
my $bool = $ua->show_progress; $ua->show_progress( $boolean );
Get/set a value indicating whether a progress bar should be displayed on the terminal as requests are processed. The default is false.
my @keys = $ua->ssl_opts; my $val = $ua->ssl_opts( $key ); $ua->ssl_opts( $key => $value );
Get/set the options for SSL connections. Without argument return the
list of options keys currently set. With a single argument return the
current value for the given option. With 2 arguments set the option
value and return the old. Setting an option to the value
undef removes this option.
The options that LWP relates to are:
When TRUE LWP will for secure protocol schemes ensure it connects to
servers that have a valid certificate matching the expected hostname. If
FALSE no checks are made and you can't be sure that you communicate with
the expected peer. The no checks behaviour was the default for
libwww-perl-5.837 and earlier releases. This option is initialized from
the PERL_LWP_SSL_VERIFY_HOSTNAME environment variable. If
this environment variable isn't set; then verify_hostname
defaults to 1.
The path to a file containing Certificate Authority certificates. A
default setting for this option is provided by checking the environment
variables PERL_LWP_SSL_CA_FILE and
HTTPS_CA_FILE in order.
The path to a directory containing files containing Certificate
Authority certificates. A default setting for this option is provided by
checking the environment variables PERL_LWP_SSL_CA_PATH and
HTTPS_CA_DIR in order.
Other options can be set and are processed directly by the SSL Socket implementation in use. See IO::Socket::SSL or Net::SSL for details.
The libwww-perl core no longer bundles protocol plugins for SSL. You will need to install LWP::Protocol::https separately to enable support for processing https-URLs.
my $secs = $ua->timeout; $ua->timeout( $secs );
Get/set the timeout value in seconds. The default value is 180 seconds, i.e. 3 minutes.
The request is aborted if no activity on the connection to the server
is observed for timeout seconds. This means that the time
it takes for the complete transaction and the request in LWP::UserAgent
method to actually return might be longer.
When a request times out, a response object is still returned. The response will have a standard HTTP Status Code (500). This response will have the Client-Warning header set to the value of Internal response. See the get in LWP::UserAgent method description below for further details.
The following methods set up when requests should be passed via a proxy server.
$ua->env_proxy;
Load proxy settings from *_proxy environment variables.
You might specify proxies like this (sh-syntax):
gopher_proxy=http://proxy.my.place/ wais_proxy=http://proxy.my.place/ no_proxy="localhost,example.com" export gopher_proxy wais_proxy no_proxy
csh or tcsh users should use the setenv command to
define these environment variables.
On systems with case insensitive environment variables there exists a
name clash between the CGI environment variables and the
HTTP_PROXY environment variable normally picked up by
env_proxy. Because of this HTTP_PROXY is not
honored for CGI scripts. The CGI_HTTP_PROXY environment
variable can be used instead.
$ua->no_proxy( @domains ); $ua->no_proxy(localhost, example.com); $ua->no_proxy(); # clear the list
Do not proxy requests to the given domains. Calling
no_proxy without any domains clears the list of
domains.
$ua->proxy(\@schemes, $proxy_url) $ua->proxy([http, ftp], http://proxy.sn.no:8001/); # For a single scheme: $ua->proxy($scheme, $proxy_url) $ua->proxy(gopher, http://proxy.sn.no:8001/); # To set multiple proxies at once: $ua->proxy([ ftp => http://ftp.example.com:8001/, [ http, https ] => http://http.example.com:8001/, ]);
Set/retrieve proxy URL for a scheme.
The first form specifies that the URL is to be used as a proxy for
access methods listed in the list in the first method argument, i.e.
http and ftp.
The second form shows a shorthand form for specifying proxy URL for a single access scheme.
The third form demonstrates setting multiple proxies at once. This is also the only form accepted by the constructor.
Handlers are code that injected at various phases during the processing of requests. The following methods are provided to manage the active handlers:
$ua->add_handler( $phase => \&cb, %matchspec )
Add handler to be invoked in the given processing phase. For how to
specify %matchspec see Matching in HTTP::Config.
The possible values $phase and the corresponding
callback signatures are as follows. Note that the handlers are
documented in the order in which they will be run, which is:
request_preprepare request_prepare request_send response_header response_data response_done response_redirect
The handler is called before the request_prepare and
other standard initialization of the request. This can be used to set up
headers and attributes that the request_prepare handler
depends on. Proxy initialization should take place here; but in general
don't register handlers for this phase.
The handler is called before the request is sent and can modify the
request any way it see fit. This can for instance be used to add certain
headers to specific requests. The method can assign a new request object
to $_[0] to replace the request that is sent fully. The
return value from the callback is ignored. If an exception is raised it
will abort the request and make the request method return a 400 Bad
request response.
This handler gets a chance of handling requests before they're sent
to the protocol handlers. It should return an HTTP::Response object if
it wishes to terminate the processing; otherwise it should return
nothing. The response_header and response_data
handlers will not be invoked for this response, but the
response_done will be.
This handler is called right after the response headers have been
received, but before any content data. The handler might set up handlers
for data and might croak to abort the request. The handler might set the
$response->{default_add_content} value to control if any
received data should be added to the response object directly. This will
initially be false if the $ua->request() method was
called with a $content_file or
$content_cb argument; otherwise true.
This handler is called for each chunk of data received for the response. The handler might croak to abort the request. This handler needs to return a TRUE value to be called again for subsequent chunks for the same request.
The handler is called after the response has been fully received, but before any redirect handling is attempted. The handler can be used to extract information or modify the response.
The handler is called in $ua->request after
response_done. If the handler returns an HTTP::Request
object we'll start over with processing this request instead.
For all of these, $handler is a code reference to the
handler that is currently being run.
$ua->get_my_handler( $phase, %matchspec ); $ua->get_my_handler( $phase, %matchspec, $init );
Will retrieve the matching handler as hash ref.
If $init is passed as a true value, create and add the
handler if it's not found. If $init is a subroutine
reference, then it's called with the created handler hash as argument.
This sub might populate the hash with extra fields; especially the
callback. If $init is a hash reference, merge the
hashes.
$ua->handlers( $phase, $request ) $ua->handlers( $phase, $response )
Returns the handlers that apply to the given request or response at the given processing phase.
$ua->remove_handler( undef, %matchspec ); $ua->remove_handler( $phase, %matchspec ); $ua->remove_handler(); # REMOVE ALL HANDLERS IN ALL PHASES
Remove handlers that match the given %matchspec. If
$phase is not provided, remove handlers from all
phases.
Be careful as calling this function with %matchspec that
is not specific enough can remove handlers not owned by you. It's
probably better to use the set_my_handler in LWP::UserAgent method
instead.
The removed handlers are returned.
$ua->set_my_handler( $phase, $cb, %matchspec ); $ua->set_my_handler($phase, undef); # remove handler for phase
Set handlers private to the executing subroutine. Works by defaulting
an owner field to the %matchspec that holds
the name of the called subroutine. You might pass an explicit
owner to override this.
If $cb is passed as undef, remove the
handler.
The methods described in this section are used to dispatch requests via the user agent. The following request methods are provided:
my $res = $ua->delete( $url ); my $res = $ua->delete( $url, $field_name => $value, ... );
This method will dispatch a DELETE request on the given
URL. Additional headers and content options are the same as for the get
in LWP::UserAgent method.
This method will use the DELETE() function from
HTTP::Request::Common to build the request. See HTTP::Request::Common
for a details on how to pass form content and other advanced
features.
my $res = $ua->get( $url ); my $res = $ua->get( $url , $field_name => $value, ... );
This method will dispatch a GET request on the given
URL. Further arguments can be given to initialize the headers of the
request. These are given as separate name/value pairs. The return value
is a response object. See HTTP::Response for a description of the
interface it provides.
There will still be a response object returned when LWP can't connect to the server specified in the URL or when other failures in protocol handlers occur. These internal responses use the standard HTTP status codes, so the responses can't be differentiated by testing the response status code alone. Error responses that LWP generates internally will have the Client-Warning header set to the value Internal response. If you need to differentiate these internal responses from responses that a remote server actually generates, you need to test this header value.
Fields names that start with : are special. These will not initialize headers of the request but will determine how the response content is treated. The following special field names are recognized:
:content_file => $filename # or $filehandle :content_cb => \&callback :read_size_hint => $bytes
If a $filename or $filehandle is provided
with the :content_file option, then the response content
will be saved here instead of in the response object. The
$filehandle may also be an object with an open file
descriptor, such as a File::Temp object. If a callback is provided with
the :content_cb option then this function will be called
for each chunk of the response content as it is received from the
server. If neither of these options are given, then the response content
will accumulate in the response object itself. This might not be
suitable for very large response bodies. Only one of
:content_file or :content_cb can be specified.
The content of unsuccessful responses will always accumulate in the
response object itself, regardless of the :content_file or
:content_cb options passed in. Note that errors writing to
the content file (for example due to permission denied or the filesystem
being full) will be reported via the Client-Aborted or
X-Died response headers, and not the
is_success method.
The :read_size_hint option is passed to the protocol
module which will try to read data from the server in chunks of this
size. A smaller value for the :read_size_hint will result
in a higher number of callback invocations.
The callback function is called with 3 arguments: a chunk of data, a
reference to the response object, and a reference to the protocol
object. The callback can abort the request by invoking
die(). The exception message will show up as the X-Died
header field in the response returned by the $ua->get()
method.
my $res = $ua->head( $url ); my $res = $ua->head( $url , $field_name => $value, ... );
This method will dispatch a HEAD request on the given
URL. Otherwise it works like the get in LWP::UserAgent method described
above.
my $bool = $ua->is_protocol_supported( $scheme );
You can use this method to test whether this user agent object
supports the specified scheme. (The scheme
might be a string (like http or ftp) or it
might be an URI object reference.)
Whether a scheme is supported is determined by the user agent's
protocols_allowed or protocols_forbidden lists
(if any), and by the capabilities of LWP. I.e., this will return true
only if LWP supports this protocol and it's permitted for this
particular object.
my $bool = $ua->is_online;
Tries to determine if you have access to the Internet. Returns
1 (true) if the built-in heuristics determine that the user
agent is able to access the Internet (over HTTP) or 0
(false).
See also LWP::Online.
my $res = $ua->mirror( $url, $filename );
This method will get the document identified by URL and store it in
file called $filename. If the file already exists, then the
request will contain an If-Modified-Since header matching
the modification time of the file. If the document on the server has not
changed since this time, then nothing happens. If the document has been
updated, it will be downloaded again. The modification time of the file
will be forced to match that of the server.
Uses move in File::Copy to attempt to atomically replace the
$filename.
The return value is an HTTP::Response object.
# Any version of HTTP::Message works with this form: my $res = $ua->patch( $url, $field_name => $value, Content => $content ); # Using hash or array references requires HTTP::Message >= 6.12 use HTTP::Request 6.12; my $res = $ua->patch( $url, \%form ); my $res = $ua->patch( $url, \@form ); my $res = $ua->patch( $url, \%form, $field_name => $value, ... ); my $res = $ua->patch( $url, $field_name => $value, Content => \%form ); my $res = $ua->patch( $url, $field_name => $value, Content => \@form );
This method will dispatch a PATCH request on the given
URL, with %form or @form providing the
key/value pairs for the fill-in form content. Additional headers and
content options are the same as for the get in LWP::UserAgent
method.
CAVEAT:
This method can only accept content that is in key-value pairs when
using HTTP::Request::Common prior to version 6.12. Any use
of hash or array references will result in an error prior to version
6.12.
This method will use the PATCH function from
HTTP::Request::Common to build the request. See HTTP::Request::Common
for a details on how to pass form content and other advanced
features.
my $res = $ua->post( $url, \%form ); my $res = $ua->post( $url, \@form ); my $res = $ua->post( $url, \%form, $field_name => $value, ... ); my $res = $ua->post( $url, $field_name => $value, Content => \%form ); my $res = $ua->post( $url, $field_name => $value, Content => \@form ); my $res = $ua->post( $url, $field_name => $value, Content => $content );
This method will dispatch a POST request on the given
URL, with %form or @form providing the
key/value pairs for the fill-in form content. Additional headers and
content options are the same as for the get in LWP::UserAgent
method.
This method will use the POST function from
HTTP::Request::Common to build the request. See HTTP::Request::Common
for a details on how to pass form content and other advanced
features.
# Any version of HTTP::Message works with this form: my $res = $ua->put( $url, $field_name => $value, Content => $content ); # Using hash or array references requires HTTP::Message >= 6.07 use HTTP::Request 6.07; my $res = $ua->put( $url, \%form ); my $res = $ua->put( $url, \@form ); my $res = $ua->put( $url, \%form, $field_name => $value, ... ); my $res = $ua->put( $url, $field_name => $value, Content => \%form ); my $res = $ua->put( $url, $field_name => $value, Content => \@form );
This method will dispatch a PUT request on the given
URL, with %form or @form providing the
key/value pairs for the fill-in form content. Additional headers and
content options are the same as for the get in LWP::UserAgent
method.
CAVEAT:
This method can only accept content that is in key-value pairs when
using HTTP::Request::Common prior to version 6.07. Any use
of hash or array references will result in an error prior to version
6.07.
This method will use the PUT function from
HTTP::Request::Common to build the request. See HTTP::Request::Common
for a details on how to pass form content and other advanced
features.
my $res = $ua->request( $request ); my $res = $ua->request( $request, $content_file ); my $res = $ua->request( $request, $content_cb ); my $res = $ua->request( $request, $content_cb, $read_size_hint );
This method will dispatch the given $request object.
Normally this will be an instance of the HTTP::Request class, but any
object with a similar interface will do. The return value is an
HTTP::Response object.
The request method will process redirects and
authentication responses transparently. This means that it may actually
send several simple requests via the simple_request in LWP::UserAgent
method described below.
The request methods described above; get in LWP::UserAgent, head in LWP::UserAgent, post in LWP::UserAgent and mirror in LWP::UserAgent will all dispatch the request they build via this method. They are convenience methods that simply hide the creation of the request object for you.
The $content_file, $content_cb and
$read_size_hint all correspond to options described with
the get in LWP::UserAgent method above. Note that errors writing to the
content file (for example due to permission denied or the filesystem
being full) will be reported via the Client-Aborted or
X-Died response headers, and not the
is_success method.
You are allowed to use a CODE reference as content in
the request object passed in. The content function should
return the content when called. The content can be returned in chunks.
The content function will be invoked repeatedly until it return an empty
string to signal that there is no more content.
my $request = HTTP::Request->new( ... ); my $res = $ua->simple_request( $request ); my $res = $ua->simple_request( $request, $content_file ); my $res = $ua->simple_request( $request, $content_cb ); my $res = $ua->simple_request( $request, $content_cb, $read_size_hint );
This method dispatches a single request and returns the response received. Arguments are the same as for the request in LWP::UserAgent described above.
The difference from request in LWP::UserAgent is that
simple_request will not try to handle redirects or
authentication responses. The request in LWP::UserAgent method will, in
fact, invoke this method for each simple request it sends.
The following methods will be invoked as requests are processed. These methods are documented here because subclasses of LWP::UserAgent might want to override their behaviour.
# This checks wantarray and can either return an array: my ($user, $pass) = $ua->get_basic_credentials( $realm, $uri, $isproxy ); # or a string that looks like "user:pass" my $creds = $ua->get_basic_credentials($realm, $uri, $isproxy);
This is called by request in LWP::UserAgent to retrieve credentials
for documents protected by Basic or Digest Authentication. The arguments
passed in is the $realm provided by the server, the
$uri requested and a boolean flag to indicate
if this is authentication against a proxy server.
The method should return a username and password. It should return an
empty list to abort the authentication resolution attempt. Subclasses
can override this method to prompt the user for the information. An
example of this can be found in lwp-request program
distributed with this library.
The base implementation simply checks a set of pre-stored member variables, set up with the credentials in LWP::UserAgent method.
$request = $ua->prepare_request( $request );
This method is invoked by simple_request in LWP::UserAgent. Its task
is to modify the given $request object by setting up
various headers based on the attributes of the user agent. The return
value should normally be the $request object passed in. If
a different request object is returned it will be the one actually
processed.
The headers affected by the base implementation are;
User-Agent, From, Range and
Cookie.
my $prog = $ua->progress( $status, $request_or_response );
This is called frequently as the response is received regardless of
how the content is processed. The method is called with
$status begin at the start of processing the request and
with $state end before the request method returns. In
between these $status will be the fraction of the response
currently received or the string tick if the fraction can't be
calculated.
When $status is begin the second argument is the
HTTP::Request object, otherwise it is the HTTP::Response object.
my $bool = $ua->redirect_ok( $prospective_request, $response );
This method is called by request in LWP::UserAgent before it tries to
follow a redirection to the request in $response. This
should return a true value if this redirection is permissible. The
$prospective_request will be the request to be sent if this
method returns true.
The base implementation will return false unless the method is in the
object's requests_redirectable list, false if the proposed
redirection is to a file://... URL, and true otherwise.
The default settings can get you up and running quickly, but there are settings you can change in order to make your life easier.
You are encouraged to install Mozilla::PublicSuffix and use HTTP::CookieJar::LWP as your cookie jar. HTTP::CookieJar::LWP provides a better security model matching that of current Web browsers when Mozilla::PublicSuffix is installed.
use HTTP::CookieJar::LWP (); my $jar = HTTP::CookieJar::LWP->new; my $ua = LWP::UserAgent->new( cookie_jar => $jar );
See cookie_jar for more information.
protocols_allowed gives you the ability to allow
arbitrary protocols.
my $ua = LWP::UserAgent->new( protocols_allowed => [ http, https ] );
This will prevent you from inadvertently following URLs like
file:///etc/passwd. See protocols_allowed.
protocols_forbidden gives you the ability to deny
arbitrary protocols.
my $ua = LWP::UserAgent->new( protocols_forbidden => [ file, mailto, ssh, ] );
This can also prevent you from inadvertently following URLs like
file:///etc/passwd. See protocols_forbidden.
See LWP for a complete overview of libwww-perl5. See lwpcook and the scripts lwp-request and lwp-download for examples of usage.
See HTTP::Request and HTTP::Response for a description of the message objects dispatched and received. See HTTP::Request::Common and HTML::Form for other ways to build request objects.
See WWW::Mechanize and WWW::Search for examples of more specialized user agents based on LWP::UserAgent.
Copyright 1995-2009 Gisle Aas.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.