.\" Automatically generated by Pod::Man 2.27 (Pod::Simple 3.28)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
.    ds C`
.    ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{
.    if \nF \{
.        de IX
.        tm Index:\\$1\t\\n%\t"\\$2"
..
.        if !\nF==2 \{
.            nr % 0
.            nr F 2
.        \}
.    \}
.\}
.rr rF
.\" ========================================================================
.\"
.IX Title "LWP::UserAgent 3"
.TH LWP::UserAgent 3 "2018-07-16" "perl v5.16.3" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
LWP::UserAgent \- Web user agent class
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 3
\& use strict;
\& use warnings;
\& use LWP::UserAgent ();
\&
\& my $ua = LWP::UserAgent\->new;
\& $ua\->timeout(10);
\& $ua\->env_proxy;
\&
\& my $response = $ua\->get(\*(Aqhttp://search.cpan.org/\*(Aq);
\&
\& if ($response\->is_success) {
\&     print $response\->decoded_content;  # or whatever
\& }
\& else {
\&     die $response\->status_line;
\& }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The LWP::UserAgent is a class implementing a web user agent.
LWP::UserAgent objects can be used to dispatch web requests.
.PP
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:
\&\*(L"get\*(R" in LWP::UserAgent, \*(L"head\*(R" in LWP::UserAgent, \*(L"post\*(R" in LWP::UserAgent,
\&\*(L"put\*(R" in LWP::UserAgent and \*(L"delete\*(R" in LWP::UserAgent.  When using these
methods, the creation of the request object is hidden as shown in the
synopsis above.
.PP
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 \fIgopher\fR and \fIftp\fR.  In order to achieve
even more similarity to HTTP-style communications, \fIgopher\fR menus and
file directories are converted to \s-1HTML\s0 documents.
.SH "CONSTRUCTOR METHODS"
.IX Header "CONSTRUCTOR METHODS"
The following constructor methods are available:
.SS "clone"
.IX Subsection "clone"
.Vb 1
\&    my $ua2 = $ua\->clone;
.Ve
.PP
Returns a copy of the LWP::UserAgent object.
.PP
\&\fB\s-1CAVEAT\s0\fR: Please be aware that the clone method does not copy or clone your
\&\f(CW\*(C`cookie_jar\*(C'\fR attribute. Due to the limited restrictions on what can be used
for your cookie jar, there is no way to clone the attribute. The \f(CW\*(C`cookie_jar\*(C'\fR
attribute will be \f(CW\*(C`undef\*(C'\fR in the new object instance.
.SS "new"
.IX Subsection "new"
.Vb 1
\&    my $ua = LWP::UserAgent\->new( %options )
.Ve
.PP
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:
.PP
.Vb 10
\&   KEY                     DEFAULT
\&   \-\-\-\-\-\-\-\-\-\-\-             \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&   agent                   "libwww\-perl/#.###"
\&   from                    undef
\&   conn_cache              undef
\&   cookie_jar              undef
\&   default_headers         HTTP::Headers\->new
\&   local_address           undef
\&   ssl_opts                { verify_hostname => 1 }
\&   max_size                undef
\&   max_redirect            7
\&   parse_head              1
\&   protocols_allowed       undef
\&   protocols_forbidden     undef
\&   requests_redirectable   [\*(AqGET\*(Aq, \*(AqHEAD\*(Aq]
\&   timeout                 180
\&   proxy                   undef
\&   no_proxy                []
.Ve
.PP
The following additional options are also accepted: If the \f(CW\*(C`env_proxy\*(C'\fR option
is passed in with a true value, then proxy settings are read from environment
variables (see \*(L"env_proxy\*(R" in LWP::UserAgent). If \f(CW\*(C`env_proxy\*(C'\fR isn't provided, the
\&\f(CW\*(C`PERL_LWP_ENV_PROXY\*(C'\fR environment variable controls if
\&\*(L"env_proxy\*(R" in LWP::UserAgent is called during initialization.  If the
\&\f(CW\*(C`keep_alive\*(C'\fR option is passed in, then a \f(CW\*(C`LWP::ConnCache\*(C'\fR is set up (see
\&\*(L"conn_cache\*(R" in LWP::UserAgent).  The \f(CW\*(C`keep_alive\*(C'\fR value is passed on as the
\&\f(CW\*(C`total_capacity\*(C'\fR for the connection cache.
.PP
\&\f(CW\*(C`proxy\*(C'\fR must be set as an arrayref of key/value pairs. \f(CW\*(C`no_proxy\*(C'\fR takes an
arrayref of domains.
.SH "ATTRIBUTES"
.IX Header "ATTRIBUTES"
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.
.PP
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.
.SS "agent"
.IX Subsection "agent"
.Vb 4
\&    my $agent = $ua\->agent;
\&    $ua\->agent(\*(AqCheckbot/0.4 \*(Aq);    # append the default to the end
\&    $ua\->agent(\*(AqMozilla/5.0\*(Aq);
\&    $ua\->agent("");                 # don\*(Aqt identify
.Ve
.PP
Get/set the product token that is used to identify the user agent on
the network. The agent value is sent as the \f(CW\*(C`User\-Agent\*(C'\fR header in
the requests.
.PP
The default is a string of the form \f(CW\*(C`libwww\-perl/#.###\*(C'\fR, where \f(CW\*(C`#.###\*(C'\fR is
substituted with the version number of this library.
.PP
If the provided string ends with space, the default \f(CW\*(C`libwww\-perl/#.###\*(C'\fR
string is appended to it.
.PP
The user agent string should be one or more simple product identifiers
with an optional version number separated by the \f(CW\*(C`/\*(C'\fR character.
.SS "conn_cache"
.IX Subsection "conn_cache"
.Vb 2
\&    my $cache_obj = $ua\->conn_cache;
\&    $ua\->conn_cache( $cache_obj );
.Ve
.PP
Get/set the LWP::ConnCache object to use.  See LWP::ConnCache
for details.
.SS "cookie_jar"
.IX Subsection "cookie_jar"
.Vb 2
\&    my $jar = $ua\->cookie_jar;
\&    $ua\->cookie_jar( $cookie_jar_obj );
.Ve
.PP
Get/set the cookie jar object to use.  The only requirement is that
the cookie jar object must implement the \f(CW\*(C`extract_cookies($response)\*(C'\fR and
\&\f(CW\*(C`add_cookie_header($request)\*(C'\fR 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.
.PP
The default is to have no cookie jar, i.e. never automatically add
\&\f(CW\*(C`Cookie\*(C'\fR headers to the requests.
.PP
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:
.PP
.Vb 1
\&  $ua\->cookie_jar({ file => "$ENV{HOME}/.cookies.txt" });
.Ve
.PP
is really just a shortcut for:
.PP
.Vb 2
\&  require HTTP::Cookies;
\&  $ua\->cookie_jar(HTTP::Cookies\->new(file => "$ENV{HOME}/.cookies.txt"));
.Ve
.SS "credentials"
.IX Subsection "credentials"
.Vb 4
\&    my $creds = $ua\->credentials();
\&    $ua\->credentials( $netloc, $realm );
\&    $ua\->credentials( $netloc, $realm, $uname, $pass );
\&    $ua\->credentials("www.example.com:80", "Some Realm", "foo", "secret");
.Ve
.PP
Get/set the user name and password to be used for a realm.
.PP
The \f(CW$netloc\fR is a string of the form \f(CW\*(C`<host>:<port>\*(C'\fR.  The username and
password will only be passed to this server.
.SS "default_header"
.IX Subsection "default_header"
.Vb 4
\&    $ua\->default_header( $field );
\&    $ua\->default_header( $field => $value );
\&    $ua\->default_header(\*(AqAccept\-Encoding\*(Aq => scalar HTTP::Message::decodable());
\&    $ua\->default_header(\*(AqAccept\-Language\*(Aq => "no, en");
.Ve
.PP
This is just a shortcut for
\&\f(CW\*(C`$ua\->default_headers\->header( $field => $value )\*(C'\fR.
.SS "default_headers"
.IX Subsection "default_headers"
.Vb 2
\&    my $headers = $ua\->default_headers;
\&    $ua\->default_headers( $headers_obj );
.Ve
.PP
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.
.SS "from"
.IX Subsection "from"
.Vb 2
\&    my $from = $ua\->from;
\&    $ua\->from(\*(Aqfoo@bar.com\*(Aq);
.Ve
.PP
Get/set the email address for the human user who controls
the requesting user agent.  The address should be machine-usable, as
defined in \s-1RFC2822\s0 <https://tools.ietf.org/html/rfc2822>. The \f(CW\*(C`from\*(C'\fR value
is sent as the \f(CW\*(C`From\*(C'\fR header in the requests.
.PP
The default is to not send a \f(CW\*(C`From\*(C'\fR header.  See
\&\*(L"default_headers\*(R" in LWP::UserAgent for the more general interface that allow
any header to be defaulted.
.SS "local_address"
.IX Subsection "local_address"
.Vb 2
\&    my $address = $ua\->local_address;
\&    $ua\->local_address( $address );
.Ve
.PP
Get/set the local interface to bind to for network connections.  The interface
can be specified as a hostname or an \s-1IP\s0 address.  This value is passed as the
\&\f(CW\*(C`LocalAddr\*(C'\fR argument to IO::Socket::INET.
.SS "max_redirect"
.IX Subsection "max_redirect"
.Vb 2
\&    my $max = $ua\->max_redirect;
\&    $ua\->max_redirect( $n );
.Ve
.PP
This reads or sets the object's limit of how many times it will obey
redirection responses in a given request cycle.
.PP
By default, the value is \f(CW7\fR. This means that if you call \*(L"request\*(R" in LWP::UserAgent
and the response is a redirect elsewhere which is in turn a
redirect, and so on seven times, then \s-1LWP\s0 gives up after that seventh
request.
.SS "max_size"
.IX Subsection "max_size"
.Vb 2
\&    my $size = $ua\->max_size;
\&    $ua\->max_size( $bytes );
.Ve
.PP
Get/set the size limit for response content.  The default is \f(CW\*(C`undef\*(C'\fR,
which means that there is no limit.  If the returned response content
is only partial, because the size limit was exceeded, then a
\&\f(CW\*(C`Client\-Aborted\*(C'\fR header will be added to the response.  The content
might end up longer than \f(CW\*(C`max_size\*(C'\fR as we abort once appending a
chunk of data makes the length exceed the limit.  The \f(CW\*(C`Content\-Length\*(C'\fR
header, if present, will indicate the length of the full content and
will normally not be the same as \f(CW\*(C`length($res\->content)\*(C'\fR.
.SS "parse_head"
.IX Subsection "parse_head"
.Vb 2
\&    my $bool = $ua\->parse_head;
\&    $ua\->parse_head( $boolean );
.Ve
.PP
Get/set a value indicating whether we should initialize response
headers from the <head> section of \s-1HTML\s0 documents. The default is
true. \fIDo not turn this off\fR unless you know what you are doing.
.SS "protocols_allowed"
.IX Subsection "protocols_allowed"
.Vb 4
\&    my $aref = $ua\->protocols_allowed;      # get allowed protocols
\&    $ua\->protocols_allowed( \e@protocols );  # allow ONLY these
\&    $ua\->protocols_allowed(undef);          # delete the list
\&    $ua\->protocols_allowed([\*(Aqhttp\*(Aq,]);      # ONLY allow http
.Ve
.PP
By default, an object has neither a \f(CW\*(C`protocols_allowed\*(C'\fR list, nor a
\&\*(L"protocols_forbidden\*(R" in LWP::UserAgent list.
.PP
This reads (or sets) this user agent's list of protocols that the
request methods will exclusively allow.  The protocol names are case
insensitive.
.PP
For example: \f(CW\*(C`$ua\->protocols_allowed( [ \*(Aqhttp\*(Aq, \*(Aqhttps\*(Aq] );\*(C'\fR
means that this user agent will \fIallow only\fR those protocols,
and attempts to use this user agent to access URLs with any other
schemes (like \f(CW\*(C`ftp://...\*(C'\fR) will result in a 500 error.
.PP
Note that having a \f(CW\*(C`protocols_allowed\*(C'\fR list causes any
\&\*(L"protocols_forbidden\*(R" in LWP::UserAgent list to be ignored.
.SS "protocols_forbidden"
.IX Subsection "protocols_forbidden"
.Vb 4
\&    my $aref = $ua\->protocols_forbidden;    # get the forbidden list
\&    $ua\->protocols_forbidden(\e@protocols);  # do not allow these
\&    $ua\->protocols_forbidden([\*(Aqhttp\*(Aq,]);    # All http reqs get a 500
\&    $ua\->protocols_forbidden(undef);        # delete the list
.Ve
.PP
This reads (or sets) this user agent's list of protocols that the
request method will \fInot\fR allow. The protocol names are case
insensitive.
.PP
For example: \f(CW\*(C`$ua\->protocols_forbidden( [ \*(Aqfile\*(Aq, \*(Aqmailto\*(Aq] );\*(C'\fR
means that this user agent will \fInot\fR allow those protocols, and
attempts to use this user agent to access URLs with those schemes
will result in a 500 error.
.SS "requests_redirectable"
.IX Subsection "requests_redirectable"
.Vb 3
\&    my $aref = $ua\->requests_redirectable;
\&    $ua\->requests_redirectable( \e@requests );
\&    $ua\->requests_redirectable([\*(AqGET\*(Aq, \*(AqHEAD\*(Aq,]); # the default
.Ve
.PP
This reads or sets the object's list of request names that
\&\*(L"redirect_ok\*(R" in LWP::UserAgent will allow redirection for. By default, this
is \f(CW\*(C`[\*(AqGET\*(Aq, \*(AqHEAD\*(Aq]\*(C'\fR, as per \s-1RFC 2616\s0 <https://tools.ietf.org/html/rfc2616>.
To change to include \f(CW\*(C`POST\*(C'\fR, consider:
.PP
.Vb 1
\&   push @{ $ua\->requests_redirectable }, \*(AqPOST\*(Aq;
.Ve
.SS "send_te"
.IX Subsection "send_te"
.Vb 2
\&    my $bool = $ua\->send_te;
\&    $ua\->send_te( $boolean );
.Ve
.PP
If true, will send a \f(CW\*(C`TE\*(C'\fR header along with the request. The default is
true. Set it to false to disable the \f(CW\*(C`TE\*(C'\fR header for systems who can't
handle it.
.SS "show_progress"
.IX Subsection "show_progress"
.Vb 2
\&    my $bool = $ua\->show_progress;
\&    $ua\->show_progress( $boolean );
.Ve
.PP
Get/set a value indicating whether a progress bar should be displayed
on the terminal as requests are processed. The default is false.
.SS "ssl_opts"
.IX Subsection "ssl_opts"
.Vb 3
\&    my @keys = $ua\->ssl_opts;
\&    my $val = $ua\->ssl_opts( $key );
\&    $ua\->ssl_opts( $key => $value );
.Ve
.PP
Get/set the options for \s-1SSL\s0 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 \f(CW\*(C`undef\*(C'\fR removes this option.
.PP
The options that \s-1LWP\s0 relates to are:
.ie n .IP """verify_hostname"" => $bool" 4
.el .IP "\f(CWverify_hostname\fR => \f(CW$bool\fR" 4
.IX Item "verify_hostname => $bool"
When \s-1TRUE LWP\s0 will for secure protocol schemes ensure it connects to servers
that have a valid certificate matching the expected hostname.  If \s-1FALSE\s0 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.
.Sp
This option is initialized from the \f(CW\*(C`PERL_LWP_SSL_VERIFY_HOSTNAME\*(C'\fR environment
variable.  If this environment variable isn't set; then \f(CW\*(C`verify_hostname\*(C'\fR
defaults to 1.
.ie n .IP """SSL_ca_file"" => $path" 4
.el .IP "\f(CWSSL_ca_file\fR => \f(CW$path\fR" 4
.IX Item "SSL_ca_file => $path"
The path to a file containing Certificate Authority certificates.
A default setting for this option is provided by checking the environment
variables \f(CW\*(C`PERL_LWP_SSL_CA_FILE\*(C'\fR and \f(CW\*(C`HTTPS_CA_FILE\*(C'\fR in order.
.ie n .IP """SSL_ca_path"" => $path" 4
.el .IP "\f(CWSSL_ca_path\fR => \f(CW$path\fR" 4
.IX Item "SSL_ca_path => $path"
The path to a directory containing files containing Certificate Authority
certificates.
A default setting for this option is provided by checking the environment
variables \f(CW\*(C`PERL_LWP_SSL_CA_PATH\*(C'\fR and \f(CW\*(C`HTTPS_CA_DIR\*(C'\fR in order.
.PP
Other options can be set and are processed directly by the \s-1SSL\s0 Socket implementation
in use.  See IO::Socket::SSL or Net::SSL for details.
.PP
The libwww-perl core no longer bundles protocol plugins for \s-1SSL. \s0 You will need
to install LWP::Protocol::https separately to enable support for processing
https-URLs.
.SS "timeout"
.IX Subsection "timeout"
.Vb 2
\&    my $secs = $ua\->timeout;
\&    $ua\->timeout( $secs );
.Ve
.PP
Get/set the timeout value in seconds. The default value is
180 seconds, i.e. 3 minutes.
.PP
The request is aborted if no activity on the connection to the server
is observed for \f(CW\*(C`timeout\*(C'\fR seconds.  This means that the time it takes
for the complete transaction and the \*(L"request\*(R" in LWP::UserAgent method to
actually return might be longer.
.PP
When a request times out, a response object is still returned.  The response
will have a standard \s-1HTTP\s0 Status Code (500).  This response will have the
\&\*(L"Client-Warning\*(R" header set to the value of \*(L"Internal response\*(R".  See the
\&\*(L"get\*(R" in LWP::UserAgent method description below for further details.
.SH "PROXY ATTRIBUTES"
.IX Header "PROXY ATTRIBUTES"
The following methods set up when requests should be passed via a
proxy server.
.SS "env_proxy"
.IX Subsection "env_proxy"
.Vb 1
\&    $ua\->env_proxy;
.Ve
.PP
Load proxy settings from \f(CW*_proxy\fR environment variables.  You might
specify proxies like this (sh-syntax):
.PP
.Vb 4
\&  gopher_proxy=http://proxy.my.place/
\&  wais_proxy=http://proxy.my.place/
\&  no_proxy="localhost,example.com"
\&  export gopher_proxy wais_proxy no_proxy
.Ve
.PP
csh or tcsh users should use the \f(CW\*(C`setenv\*(C'\fR command to define these
environment variables.
.PP
On systems with case insensitive environment variables there exists a
name clash between the \s-1CGI\s0 environment variables and the \f(CW\*(C`HTTP_PROXY\*(C'\fR
environment variable normally picked up by \f(CW\*(C`env_proxy\*(C'\fR.  Because of
this \f(CW\*(C`HTTP_PROXY\*(C'\fR is not honored for \s-1CGI\s0 scripts.  The
\&\f(CW\*(C`CGI_HTTP_PROXY\*(C'\fR environment variable can be used instead.
.SS "no_proxy"
.IX Subsection "no_proxy"
.Vb 3
\&    $ua\->no_proxy( @domains );
\&    $ua\->no_proxy(\*(Aqlocalhost\*(Aq, \*(Aqexample.com\*(Aq);
\&    $ua\->no_proxy(); # clear the list
.Ve
.PP
Do not proxy requests to the given domains.  Calling \f(CW\*(C`no_proxy\*(C'\fR without
any domains clears the list of domains.
.SS "proxy"
.IX Subsection "proxy"
.Vb 2
\&    $ua\->proxy(\e@schemes, $proxy_url)
\&    $ua\->proxy([\*(Aqhttp\*(Aq, \*(Aqftp\*(Aq], \*(Aqhttp://proxy.sn.no:8001/\*(Aq);
\&
\&    # For a single scheme:
\&    $ua\->proxy($scheme, $proxy_url)
\&    $ua\->proxy(\*(Aqgopher\*(Aq, \*(Aqhttp://proxy.sn.no:8001/\*(Aq);
\&
\&    # To set multiple proxies at once:
\&    $ua\->proxy([
\&        ftp => \*(Aqhttp://ftp.example.com:8001/\*(Aq,
\&        [ \*(Aqhttp\*(Aq, \*(Aqhttps\*(Aq ] => \*(Aqhttp://http.example.com:8001/\*(Aq,
\&    ]);
.Ve
.PP
Set/retrieve proxy \s-1URL\s0 for a scheme.
.PP
The first form specifies that the \s-1URL\s0 is to be used as a proxy for
access methods listed in the list in the first method argument,
i.e. \f(CW\*(C`http\*(C'\fR and \f(CW\*(C`ftp\*(C'\fR.
.PP
The second form shows a shorthand form for specifying
proxy \s-1URL\s0 for a single access scheme.
.PP
The third form demonstrates setting multiple proxies at once. This is also
the only form accepted by the constructor.
.SH "HANDLERS"
.IX Header "HANDLERS"
Handlers are code that injected at various phases during the
processing of requests.  The following methods are provided to manage
the active handlers:
.SS "add_handler"
.IX Subsection "add_handler"
.Vb 1
\&    $ua\->add_handler( $phase => \e&cb, %matchspec )
.Ve
.PP
Add handler to be invoked in the given processing phase.  For how to
specify \f(CW%matchspec\fR see \*(L"Matching\*(R" in HTTP::Config.
.PP
The possible values \f(CW$phase\fR and the corresponding callback signatures are:
.ie n .IP "response_data => sub { my($response, $ua, $h, $data) = @_; ... }" 4
.el .IP "response_data => sub { my($response, \f(CW$ua\fR, \f(CW$h\fR, \f(CW$data\fR) = \f(CW@_\fR; ... }" 4
.IX Item "response_data => sub { my($response, $ua, $h, $data) = @_; ... }"
This handler is called for each chunk of data received for the
response.  The handler might croak to abort the request.
.Sp
This handler needs to return a \s-1TRUE\s0 value to be called again for
subsequent chunks for the same request.
.ie n .IP "response_done => sub { my($response, $ua, $h) = @_; ... }" 4
.el .IP "response_done => sub { my($response, \f(CW$ua\fR, \f(CW$h\fR) = \f(CW@_\fR; ... }" 4
.IX Item "response_done => sub { my($response, $ua, $h) = @_; ... }"
The handler is called after the response has been fully received, but
before any redirect handling is attempted.  The handler can be used to
extract information or modify the response.
.ie n .IP "response_header => sub { my($response, $ua, $h) = @_; ... }" 4
.el .IP "response_header => sub { my($response, \f(CW$ua\fR, \f(CW$h\fR) = \f(CW@_\fR; ... }" 4
.IX Item "response_header => sub { my($response, $ua, $h) = @_; ... }"
This handler is called right after the response headers have been
received, but before any content data.  The handler might set up
handlers for data and might croak to abort the request.
.Sp
The handler might set the \f(CW$response\fR\->{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 \f(CW$ua\fR\->\fIrequest()\fR method
was called with a \f(CW$content_file\fR or \f(CW$content_cb\fR argument; otherwise true.
.ie n .IP "request_prepare => sub { my($request, $ua, $h) = @_; ... }" 4
.el .IP "request_prepare => sub { my($request, \f(CW$ua\fR, \f(CW$h\fR) = \f(CW@_\fR; ... }" 4
.IX Item "request_prepare => sub { my($request, $ua, $h) = @_; ... }"
The handler is called before the request is sent and can modify the
request any way it see fit.  This can for instance be used to add
certain headers to specific requests.
.Sp
The method can assign a new request object to \f(CW$_\fR[0] to replace the
request that is sent fully.
.Sp
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
\&\*(L"400 Bad request\*(R" response.
.ie n .IP "request_preprepare => sub { my($request, $ua, $h) = @_; ... }" 4
.el .IP "request_preprepare => sub { my($request, \f(CW$ua\fR, \f(CW$h\fR) = \f(CW@_\fR; ... }" 4
.IX Item "request_preprepare => sub { my($request, $ua, $h) = @_; ... }"
The handler is called before the \f(CW\*(C`request_prepare\*(C'\fR and other standard
initialization of the request.  This can be used to set up headers
and attributes that the \f(CW\*(C`request_prepare\*(C'\fR handler depends on.  Proxy
initialization should take place here; but in general don't register
handlers for this phase.
.ie n .IP "request_send => sub { my($request, $ua, $h) = @_; ... }" 4
.el .IP "request_send => sub { my($request, \f(CW$ua\fR, \f(CW$h\fR) = \f(CW@_\fR; ... }" 4
.IX Item "request_send => sub { my($request, $ua, $h) = @_; ... }"
This handler gets a chance of handling requests before they're sent to the
protocol handlers.  It should return an HTTP::Response object if it
wishes to terminate the processing; otherwise it should return nothing.
.Sp
The \f(CW\*(C`response_header\*(C'\fR and \f(CW\*(C`response_data\*(C'\fR handlers will not be
invoked for this response, but the \f(CW\*(C`response_done\*(C'\fR will be.
.ie n .IP "response_redirect => sub { my($response, $ua, $h) = @_; ... }" 4
.el .IP "response_redirect => sub { my($response, \f(CW$ua\fR, \f(CW$h\fR) = \f(CW@_\fR; ... }" 4
.IX Item "response_redirect => sub { my($response, $ua, $h) = @_; ... }"
The handler is called in \f(CW$ua\fR\->request after \f(CW\*(C`response_done\*(C'\fR.  If the
handler returns an HTTP::Request object we'll start over with processing
this request instead.
.SS "get_my_handler"
.IX Subsection "get_my_handler"
.Vb 2
\&    $ua\->get_my_handler( $phase, %matchspec );
\&    $ua\->get_my_handler( $phase, %matchspec, $init );
.Ve
.PP
Will retrieve the matching handler as hash ref.
.PP
If \f(CW$init\fR is passed as a true value, create and add the
handler if it's not found.  If \f(CW$init\fR is a subroutine reference, then
it's called with the created handler hash as argument.  This sub might
populate the hash with extra fields; especially the callback.  If
\&\f(CW$init\fR is a hash reference, merge the hashes.
.SS "handlers"
.IX Subsection "handlers"
.Vb 2
\&    $ua\->handlers( $phase, $request )
\&    $ua\->handlers( $phase, $response )
.Ve
.PP
Returns the handlers that apply to the given request or response at
the given processing phase.
.SS "remove_handler"
.IX Subsection "remove_handler"
.Vb 3
\&    $ua\->remove_handler( undef, %matchspec );
\&    $ua\->remove_handler( $phase, %matchspec );
\&    $ua\->remove_handlers(); # REMOVE ALL HANDLERS IN ALL PHASES
.Ve
.PP
Remove handlers that match the given \f(CW%matchspec\fR.  If \f(CW$phase\fR is not
provided, remove handlers from all phases.
.PP
Be careful as calling this function with \f(CW%matchspec\fR that is not
specific enough can remove handlers not owned by you.  It's probably
better to use the \*(L"set_my_handler\*(R" in LWP::UserAgent method instead.
.PP
The removed handlers are returned.
.SS "set_my_handler"
.IX Subsection "set_my_handler"
.Vb 2
\&    $ua\->set_my_handler( $phase, $cb, %matchspec );
\&    $ua\->set_my_handler($phase, undef); # remove handler for phase
.Ve
.PP
Set handlers private to the executing subroutine.  Works by defaulting
an \f(CW\*(C`owner\*(C'\fR field to the \f(CW%matchspec\fR that holds the name of the called
subroutine.  You might pass an explicit \f(CW\*(C`owner\*(C'\fR to override this.
.PP
If \f(CW$cb\fR is passed as \f(CW\*(C`undef\*(C'\fR, remove the handler.
.SH "REQUEST METHODS"
.IX Header "REQUEST METHODS"
The methods described in this section are used to dispatch requests
via the user agent.  The following request methods are provided:
.SS "delete"
.IX Subsection "delete"
.Vb 2
\&    my $res = $ua\->delete( $url );
\&    my $res = $ua\->delete( $url, $field_name => $value, ... );
.Ve
.PP
This method will dispatch a \f(CW\*(C`DELETE\*(C'\fR request on the given \s-1URL. \s0 Additional
headers and content options are the same as for the \*(L"get\*(R" in LWP::UserAgent
method.
.PP
This method will use the \s-1\fIDELETE\s0()\fR 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.
.SS "get"
.IX Subsection "get"
.Vb 2
\&    my $res = $ua\->get( $url );
\&    my $res = $ua\->get( $url , $field_name => $value, ... );
.Ve
.PP
This method will dispatch a \f(CW\*(C`GET\*(C'\fR request on the given \s-1URL. \s0 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.
.PP
There will still be a response object returned when \s-1LWP\s0 can't connect to the
server specified in the \s-1URL\s0 or when other failures in protocol handlers occur.
These internal responses use the standard \s-1HTTP\s0 status codes, so the responses
can't be differentiated by testing the response status code alone.  Error
responses that \s-1LWP\s0 generates internally will have the \*(L"Client-Warning\*(R" header
set to the value \*(L"Internal response\*(R".  If you need to differentiate these
internal responses from responses that a remote server actually generates, you
need to test this header value.
.PP
Fields names that start with \*(L":\*(R" 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:
.PP
.Vb 3
\&    :content_file   => $filename
\&    :content_cb     => \e&callback
\&    :read_size_hint => $bytes
.Ve
.PP
If a \f(CW$filename\fR is provided with the \f(CW\*(C`:content_file\*(C'\fR option, then the
response content will be saved here instead of in the response
object.  If a callback is provided with the \f(CW\*(C`:content_cb\*(C'\fR 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 \f(CW\*(C`:content_file\*(C'\fR or \f(CW\*(C`:content_cb\*(C'\fR can be
specified.  The content of unsuccessful responses will always
accumulate in the response object itself, regardless of the
\&\f(CW\*(C`:content_file\*(C'\fR or \f(CW\*(C`:content_cb\*(C'\fR 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 \f(CW\*(C`Client\-Aborted\*(C'\fR
or \f(CW\*(C`X\-Died\*(C'\fR response headers, and not the \f(CW\*(C`is_success\*(C'\fR method.
.PP
The \f(CW\*(C`:read_size_hint\*(C'\fR 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 \f(CW\*(C`:read_size_hint\*(C'\fR will result in a higher
number of callback invocations.
.PP
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 \fIdie()\fR.  The
exception message will show up as the \*(L"X\-Died\*(R" header field in the
response returned by the \fIget()\fR function.
.SS "head"
.IX Subsection "head"
.Vb 2
\&    my $res = $ua\->head( $url );
\&    my $res = $ua\->head( $url , $field_name => $value, ... );
.Ve
.PP
This method will dispatch a \f(CW\*(C`HEAD\*(C'\fR request on the given \s-1URL.\s0
Otherwise it works like the \*(L"get\*(R" in LWP::UserAgent method described above.
.SS "is_protocol_supported"
.IX Subsection "is_protocol_supported"
.Vb 1
\&    my $bool = $ua\->is_protocol_supported( $scheme );
.Ve
.PP
You can use this method to test whether this user agent object supports the
specified \f(CW\*(C`scheme\*(C'\fR.  (The \f(CW\*(C`scheme\*(C'\fR might be a string (like \f(CW\*(C`http\*(C'\fR or
\&\f(CW\*(C`ftp\*(C'\fR) or it might be an \s-1URI\s0 object reference.)
.PP
Whether a scheme is supported is determined by the user agent's
\&\f(CW\*(C`protocols_allowed\*(C'\fR or \f(CW\*(C`protocols_forbidden\*(C'\fR lists (if any), and by
the capabilities of \s-1LWP.  I\s0.e., this will return true only if \s-1LWP\s0
supports this protocol \fIand\fR it's permitted for this particular
object.
.SS "is_online"
.IX Subsection "is_online"
.Vb 1
\&    my $bool = $ua\->is_online;
.Ve
.PP
Tries to determine if you have access to the Internet. Returns \f(CW1\fR (true)
if the built-in heuristics determine that the user agent is
able to access the Internet (over \s-1HTTP\s0) or \f(CW0\fR (false).
.PP
See also LWP::Online.
.SS "mirror"
.IX Subsection "mirror"
.Vb 1
\&    my $res = $ua\->mirror( $url, $filename );
.Ve
.PP
This method will get the document identified by \s-1URL\s0 and store it in
file called \f(CW$filename\fR.  If the file already exists, then the request
will contain an \f(CW\*(C`If\-Modified\-Since\*(C'\fR 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.
.PP
The return value is an HTTP::Response object.
.SS "post"
.IX Subsection "post"
.Vb 6
\&    my $res = $ua\->post( $url, \e%form );
\&    my $res = $ua\->post( $url, \e@form );
\&    my $res = $ua\->post( $url, \e%form, $field_name => $value, ... );
\&    my $res = $ua\->post( $url, $field_name => $value, Content => \e%form );
\&    my $res = $ua\->post( $url, $field_name => $value, Content => \e@form );
\&    my $res = $ua\->post( $url, $field_name => $value, Content => $content );
.Ve
.PP
This method will dispatch a \f(CW\*(C`POST\*(C'\fR request on the given \s-1URL,\s0 with
\&\f(CW%form\fR or \f(CW@form\fR providing the key/value pairs for the fill-in form
content. Additional headers and content options are the same as for
the \*(L"get\*(R" in LWP::UserAgent method.
.PP
This method will use the \f(CW\*(C`POST\*(C'\fR 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.
.SS "put"
.IX Subsection "put"
.Vb 2
\&    # 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, \e%form );
\&    my $res = $ua\->put( $url, \e@form );
\&    my $res = $ua\->put( $url, \e%form, $field_name => $value, ... );
\&    my $res = $ua\->put( $url, $field_name => $value, Content => \e%form );
\&    my $res = $ua\->put( $url, $field_name => $value, Content => \e@form );
.Ve
.PP
This method will dispatch a \f(CW\*(C`PUT\*(C'\fR request on the given \s-1URL,\s0 with
\&\f(CW%form\fR or \f(CW@form\fR providing the key/value pairs for the fill-in form
content. Additional headers and content options are the same as for
the \*(L"get\*(R" in LWP::UserAgent method.
.PP
\&\s-1CAVEAT:\s0
.PP
This method can only accept content that is in key-value pairs when using
HTTP::Request::Common prior to version \f(CW6.07\fR. Any use of hash or array
references will result in an error prior to version \f(CW6.07\fR.
.PP
This method will use the \f(CW\*(C`PUT\*(C'\fR 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.
.SS "request"
.IX Subsection "request"
.Vb 4
\&    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, $read_size_hint );
.Ve
.PP
This method will dispatch the given \f(CW$request\fR 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.
.PP
The \f(CW\*(C`request\*(C'\fR method will process redirects and authentication
responses transparently. This means that it may actually send several
simple requests via the \*(L"simple_request\*(R" in LWP::UserAgent method described below.
.PP
The request methods described above; \*(L"get\*(R" in LWP::UserAgent, \*(L"head\*(R" in LWP::UserAgent,
\&\*(L"post\*(R" in LWP::UserAgent and \*(L"mirror\*(R" 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.
.PP
The \f(CW$content_file\fR, \f(CW$content_cb\fR and \f(CW$read_size_hint\fR all correspond to
options described with the \*(L"get\*(R" 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 \f(CW\*(C`Client\-Aborted\*(C'\fR
or \f(CW\*(C`X\-Died\*(C'\fR response headers, and not the \f(CW\*(C`is_success\*(C'\fR method.
.PP
You are allowed to use a \s-1CODE\s0 reference as \f(CW\*(C`content\*(C'\fR in the request
object passed in.  The \f(CW\*(C`content\*(C'\fR 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.
.SS "simple_request"
.IX Subsection "simple_request"
.Vb 5
\&    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, $read_size_hint );
.Ve
.PP
This method dispatches a single request and returns the response
received.  Arguments are the same as for the \*(L"request\*(R" in LWP::UserAgent described above.
.PP
The difference from \*(L"request\*(R" in LWP::UserAgent is that \f(CW\*(C`simple_request\*(C'\fR will not try to
handle redirects or authentication responses.  The \*(L"request\*(R" in LWP::UserAgent method
will, in fact, invoke this method for each simple request it sends.
.SH "CALLBACK METHODS"
.IX Header "CALLBACK METHODS"
The following methods will be invoked as requests are processed. These
methods are documented here because subclasses of LWP::UserAgent
might want to override their behaviour.
.SS "get_basic_credentials"
.IX Subsection "get_basic_credentials"
.Vb 4
\&    # This checks wantarray and can either return an array:
\&    my ($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, $isproxy);
.Ve
.PP
This is called by \*(L"request\*(R" in LWP::UserAgent to retrieve credentials for documents
protected by Basic or Digest Authentication.  The arguments passed in
is the \f(CW$realm\fR provided by the server, the \f(CW$uri\fR requested and a
\&\f(CW\*(C`boolean flag\*(C'\fR to indicate if this is authentication against a proxy server.
.PP
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 \f(CW\*(C`lwp\-request\*(C'\fR program distributed
with this library.
.PP
The base implementation simply checks a set of pre-stored member
variables, set up with the \*(L"credentials\*(R" in LWP::UserAgent method.
.SS "prepare_request"
.IX Subsection "prepare_request"
.Vb 1
\&    $request = $ua\->prepare_request( $request );
.Ve
.PP
This method is invoked by \*(L"simple_request\*(R" in LWP::UserAgent. Its task is
to modify the given \f(CW$request\fR object by setting up various headers based
on the attributes of the user agent. The return value should normally be the
\&\f(CW$request\fR object passed in.  If a different request object is returned
it will be the one actually processed.
.PP
The headers affected by the base implementation are; \f(CW\*(C`User\-Agent\*(C'\fR,
\&\f(CW\*(C`From\*(C'\fR, \f(CW\*(C`Range\*(C'\fR and \f(CW\*(C`Cookie\*(C'\fR.
.SS "progress"
.IX Subsection "progress"
.Vb 1
\&    my $prog = $ua\->progress( $status, $request_or_response );
.Ve
.PP
This is called frequently as the response is received regardless of
how the content is processed.  The method is called with \f(CW$status\fR
\&\*(L"begin\*(R" at the start of processing the request and with \f(CW$state\fR \*(L"end\*(R"
before the request method returns.  In between these \f(CW$status\fR will be
the fraction of the response currently received or the string \*(L"tick\*(R"
if the fraction can't be calculated.
.PP
When \f(CW$status\fR is \*(L"begin\*(R" the second argument is the HTTP::Request object,
otherwise it is the HTTP::Response object.
.SS "redirect_ok"
.IX Subsection "redirect_ok"
.Vb 1
\&    my $bool = $ua\->redirect_ok( $prospective_request, $response );
.Ve
.PP
This method is called by \*(L"request\*(R" in LWP::UserAgent before it tries to follow a
redirection to the request in \f(CW$response\fR.  This should return a true
value if this redirection is permissible.  The \f(CW$prospective_request\fR
will be the request to be sent if this method returns true.
.PP
The base implementation will return false unless the method
is in the object's \f(CW\*(C`requests_redirectable\*(C'\fR list,
false if the proposed redirection is to a \f(CW\*(C`file://...\*(C'\fR
\&\s-1URL,\s0 and true otherwise.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
See \s-1LWP\s0 for a complete overview of libwww\-perl5.  See lwpcook
and the scripts \fIlwp-request\fR and \fIlwp-download\fR for examples of
usage.
.PP
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.
.PP
See WWW::Mechanize and WWW::Search for examples of more
specialized user agents based on LWP::UserAgent.
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
Copyright 1995\-2009 Gisle Aas.
.PP
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.