cgi.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

Use another name for the argument, if one is available. 
For example, \-value is an alias for \-values.
.IP "2." 4
Change the capitalization, e.g. \-Values
.IP "3." 4
Put quotes around the argument name, e.g. '\-values'
.PP
Many routines will do something useful with a named argument that it
doesn't recognize.  For example, you can produce non-standard \s-1HTTP\s0
header fields by providing them as named arguments:
.PP
.Vb 4
\&  print $q\->header(\-type  =>  \*(Aqtext/html\*(Aq,
\&                   \-cost  =>  \*(AqThree smackers\*(Aq,
\&                   \-annoyance_level => \*(Aqhigh\*(Aq,
\&                   \-complaints_to   => \*(Aqbit bucket\*(Aq);
.Ve
.PP
This will produce the following nonstandard \s-1HTTP\s0 header:
.PP
.Vb 5
\&   HTTP/1.0 200 OK
\&   Cost: Three smackers
\&   Annoyance\-level: high
\&   Complaints\-to: bit bucket
\&   Content\-type: text/html
.Ve
.PP
Notice the way that underscores are translated automatically into
hyphens.  HTML-generating routines perform a different type of
translation.
.PP
This feature allows you to keep up with the rapidly changing \s-1HTTP\s0 and
\&\s-1HTML\s0 \*(L"standards\*(R".
.Sh "\s-1CREATING\s0 A \s-1NEW\s0 \s-1QUERY\s0 \s-1OBJECT\s0 (OBJECT-ORIENTED \s-1STYLE\s0):"
.IX Subsection "CREATING A NEW QUERY OBJECT (OBJECT-ORIENTED STYLE):"
.Vb 1
\&     $query = new CGI;
.Ve
.PP
This will parse the input (from both \s-1POST\s0 and \s-1GET\s0 methods) and store
it into a perl5 object called \f(CW$query\fR.
.PP
Any filehandles from file uploads will have their position reset to 
the beginning of the file.
.Sh "\s-1CREATING\s0 A \s-1NEW\s0 \s-1QUERY\s0 \s-1OBJECT\s0 \s-1FROM\s0 \s-1AN\s0 \s-1INPUT\s0 \s-1FILE\s0"
.IX Subsection "CREATING A NEW QUERY OBJECT FROM AN INPUT FILE"
.Vb 1
\&     $query = new CGI(INPUTFILE);
.Ve
.PP
If you provide a file handle to the \fInew()\fR method, it will read
parameters from the file (or \s-1STDIN\s0, or whatever).  The file can be in
any of the forms describing below under debugging (i.e. a series of
newline delimited TAG=VALUE pairs will work).  Conveniently, this type
of file is created by the \fIsave()\fR method (see below).  Multiple records
can be saved and restored.
.PP
Perl purists will be pleased to know that this syntax accepts
references to file handles, or even references to filehandle globs,
which is the \*(L"official\*(R" way to pass a filehandle:
.PP
.Vb 1
\&    $query = new CGI(\e*STDIN);
.Ve
.PP
You can also initialize the \s-1CGI\s0 object with a FileHandle or IO::File
object.
.PP
If you are using the function-oriented interface and want to
initialize \s-1CGI\s0 state from a file handle, the way to do this is with
\&\fB\f(BIrestore_parameters()\fB\fR.  This will (re)initialize the
default \s-1CGI\s0 object from the indicated file handle.
.PP
.Vb 3
\&    open (IN,"test.in") || die;
\&    restore_parameters(IN);
\&    close IN;
.Ve
.PP
You can also initialize the query object from an associative array
reference:
.PP
.Vb 4
\&    $query = new CGI( {\*(Aqdinosaur\*(Aq=>\*(Aqbarney\*(Aq,
\&                       \*(Aqsong\*(Aq=>\*(AqI love you\*(Aq,
\&                       \*(Aqfriends\*(Aq=>[qw/Jessica George Nancy/]}
\&                    );
.Ve
.PP
or from a properly formatted, URL-escaped query string:
.PP
.Vb 1
\&    $query = new CGI(\*(Aqdinosaur=barney&color=purple\*(Aq);
.Ve
.PP
or from a previously existing \s-1CGI\s0 object (currently this clones the
parameter list, but none of the other object-specific fields, such as
autoescaping):
.PP
.Vb 2
\&    $old_query = new CGI;
\&    $new_query = new CGI($old_query);
.Ve
.PP
To create an empty query, initialize it from an empty string or hash:
.PP
.Vb 1
\&   $empty_query = new CGI("");
\&
\&       \-or\-
\&
\&   $empty_query = new CGI({});
.Ve
.Sh "\s-1FETCHING\s0 A \s-1LIST\s0 \s-1OF\s0 \s-1KEYWORDS\s0 \s-1FROM\s0 \s-1THE\s0 \s-1QUERY:\s0"
.IX Subsection "FETCHING A LIST OF KEYWORDS FROM THE QUERY:"
.Vb 1
\&     @keywords = $query\->keywords
.Ve
.PP
If the script was invoked as the result of an <\s-1ISINDEX\s0> search, the
parsed keywords can be obtained as an array using the \fIkeywords()\fR method.
.Sh "\s-1FETCHING\s0 \s-1THE\s0 \s-1NAMES\s0 \s-1OF\s0 \s-1ALL\s0 \s-1THE\s0 \s-1PARAMETERS\s0 \s-1PASSED\s0 \s-1TO\s0 \s-1YOUR\s0 \s-1SCRIPT:\s0"
.IX Subsection "FETCHING THE NAMES OF ALL THE PARAMETERS PASSED TO YOUR SCRIPT:"
.Vb 1
\&     @names = $query\->param
.Ve
.PP
If the script was invoked with a parameter list
(e.g. \*(L"name1=value1&name2=value2&name3=value3\*(R"), the \fIparam()\fR method
will return the parameter names as a list.  If the script was invoked
as an <\s-1ISINDEX\s0> script and contains a string without ampersands
(e.g. \*(L"value1+value2+value3\*(R") , there will be a single parameter named
\&\*(L"keywords\*(R" containing the \*(L"+\*(R"\-delimited keywords.
.PP
\&\s-1NOTE:\s0 As of version 1.5, the array of parameter names returned will
be in the same order as they were submitted by the browser.
Usually this order is the same as the order in which the 
parameters are defined in the form (however, this isn't part
of the spec, and so isn't guaranteed).
.Sh "\s-1FETCHING\s0 \s-1THE\s0 \s-1VALUE\s0 \s-1OR\s0 \s-1VALUES\s0 \s-1OF\s0 A \s-1SINGLE\s0 \s-1NAMED\s0 \s-1PARAMETER:\s0"
.IX Subsection "FETCHING THE VALUE OR VALUES OF A SINGLE NAMED PARAMETER:"
.Vb 1
\&    @values = $query\->param(\*(Aqfoo\*(Aq);
\&
\&              \-or\-
\&
\&    $value = $query\->param(\*(Aqfoo\*(Aq);
.Ve
.PP
Pass the \fIparam()\fR method a single argument to fetch the value of the
named parameter. If the parameter is multivalued (e.g. from multiple
selections in a scrolling list), you can ask to receive an array.  Otherwise
the method will return a single value.
.PP
If a value is not given in the query string, as in the queries
\&\*(L"name1=&name2=\*(R" or \*(L"name1&name2\*(R", it will be returned as an empty
string.  This feature is new in 2.63.
.PP
If the parameter does not exist at all, then \fIparam()\fR will return undef
in a scalar context, and the empty list in a list context.
.Sh "\s-1SETTING\s0 \s-1THE\s0 \s-1VALUE\s0(S) \s-1OF\s0 A \s-1NAMED\s0 \s-1PARAMETER:\s0"
.IX Subsection "SETTING THE VALUE(S) OF A NAMED PARAMETER:"
.Vb 1
\&    $query\->param(\*(Aqfoo\*(Aq,\*(Aqan\*(Aq,\*(Aqarray\*(Aq,\*(Aqof\*(Aq,\*(Aqvalues\*(Aq);
.Ve
.PP
This sets the value for the named parameter 'foo' to an array of
values.  This is one way to change the value of a field \s-1AFTER\s0
the script has been invoked once before.  (Another way is with
the \-override parameter accepted by all methods that generate
form elements.)
.PP
\&\fIparam()\fR also recognizes a named parameter style of calling described
in more detail later:
.PP
.Vb 1
\&    $query\->param(\-name=>\*(Aqfoo\*(Aq,\-values=>[\*(Aqan\*(Aq,\*(Aqarray\*(Aq,\*(Aqof\*(Aq,\*(Aqvalues\*(Aq]);
\&
\&                              \-or\-
\&
\&    $query\->param(\-name=>\*(Aqfoo\*(Aq,\-value=>\*(Aqthe value\*(Aq);
.Ve
.Sh "\s-1APPENDING\s0 \s-1ADDITIONAL\s0 \s-1VALUES\s0 \s-1TO\s0 A \s-1NAMED\s0 \s-1PARAMETER:\s0"
.IX Subsection "APPENDING ADDITIONAL VALUES TO A NAMED PARAMETER:"
.Vb 1
\&   $query\->append(\-name=>\*(Aqfoo\*(Aq,\-values=>[\*(Aqyet\*(Aq,\*(Aqmore\*(Aq,\*(Aqvalues\*(Aq]);
.Ve
.PP
This adds a value or list of values to the named parameter.  The
values are appended to the end of the parameter if it already exists.
Otherwise the parameter is created.  Note that this method only
recognizes the named argument calling syntax.
.Sh "\s-1IMPORTING\s0 \s-1ALL\s0 \s-1PARAMETERS\s0 \s-1INTO\s0 A \s-1NAMESPACE:\s0"
.IX Subsection "IMPORTING ALL PARAMETERS INTO A NAMESPACE:"
.Vb 1
\&   $query\->import_names(\*(AqR\*(Aq);
.Ve
.PP
This creates a series of variables in the 'R' namespace.  For example,
\&\f(CW$R::foo\fR, \f(CW@R:foo\fR.  For keyword lists, a variable \f(CW@R::keywords\fR will appear.
If no namespace is given, this method will assume 'Q'.
\&\s-1WARNING:\s0  don't import anything into 'main'; this is a major security
risk!!!!
.PP
\&\s-1NOTE\s0 1: Variable names are transformed as necessary into legal Perl
variable names.  All non-legal characters are transformed into
underscores.  If you need to keep the original names, you should use
the \fIparam()\fR method instead to access \s-1CGI\s0 variables by name.
.PP
\&\s-1NOTE\s0 2: In older versions, this method was called \fB\f(BIimport()\fB\fR.  As of version 2.20, 
this name has been removed completely to avoid conflict with the built-in
Perl module \fBimport\fR operator.
.Sh "\s-1DELETING\s0 A \s-1PARAMETER\s0 \s-1COMPLETELY:\s0"
.IX Subsection "DELETING A PARAMETER COMPLETELY:"
.Vb 1
\&    $query\->delete(\*(Aqfoo\*(Aq,\*(Aqbar\*(Aq,\*(Aqbaz\*(Aq);
.Ve
.PP
This completely clears a list of parameters.  It sometimes useful for
resetting parameters that you don't want passed down between script
invocations.
.PP
If you are using the function call interface, use \*(L"\fIDelete()\fR\*(R" instead
to avoid conflicts with Perl's built-in delete operator.
.Sh "\s-1DELETING\s0 \s-1ALL\s0 \s-1PARAMETERS:\s0"
.IX Subsection "DELETING ALL PARAMETERS:"
.Vb 1
\&   $query\->delete_all();
.Ve
.PP
This clears the \s-1CGI\s0 object completely.  It might be useful to ensure
that all the defaults are taken when you create a fill-out form.
.PP
Use \fIDelete_all()\fR instead if you are using the function call interface.
.Sh "\s-1HANDLING\s0 NON-URLENCODED \s-1ARGUMENTS\s0"
.IX Subsection "HANDLING NON-URLENCODED ARGUMENTS"
If POSTed data is not of type application/x\-www\-form\-urlencoded or
multipart/form\-data, then the POSTed data will not be processed, but
instead be returned as-is in a parameter named \s-1POSTDATA\s0.  To retrieve
it, use code like this:
.PP
.Vb 1
\&   my $data = $query\->param(\*(AqPOSTDATA\*(Aq);
.Ve
.PP
(If you don't know what the preceding means, don't worry about it.  It
only affects people trying to use \s-1CGI\s0 for \s-1XML\s0 processing and other
specialized tasks.)
.Sh "\s-1DIRECT\s0 \s-1ACCESS\s0 \s-1TO\s0 \s-1THE\s0 \s-1PARAMETER\s0 \s-1LIST:\s0"
.IX Subsection "DIRECT ACCESS TO THE PARAMETER LIST:"
.Vb 2
\&   $q\->param_fetch(\*(Aqaddress\*(Aq)\->[1] = \*(Aq1313 Mockingbird Lane\*(Aq;
\&   unshift @{$q\->param_fetch(\-name=>\*(Aqaddress\*(Aq)},\*(AqGeorge Munster\*(Aq;
.Ve
.PP
If you need access to the parameter list in a way that isn't covered
by the methods above, you can obtain a direct reference to it by
calling the \fB\f(BIparam_fetch()\fB\fR method with the name of the .  This
will return an array reference to the named parameters, which you then
can manipulate in any way you like.
.PP
You can also use a named argument style using the \fB\-name\fR argument.
.Sh "\s-1FETCHING\s0 \s-1THE\s0 \s-1PARAMETER\s0 \s-1LIST\s0 \s-1AS\s0 A \s-1HASH:\s0"
.IX Subsection "FETCHING THE PARAMETER LIST AS A HASH:"
.Vb 4
\&    $params = $q\->Vars;
\&    print $params\->{\*(Aqaddress\*(Aq};
\&    @foo = split("\e0",$params\->{\*(Aqfoo\*(Aq});
\&    %params = $q\->Vars;
\&
\&    use CGI \*(Aq:cgi\-lib\*(Aq;
\&    $params = Vars;
.Ve
.PP
Many people want to fetch the entire parameter list as a hash in which
the keys are the names of the \s-1CGI\s0 parameters, and the values are the
parameters' values.  The \fIVars()\fR method does this.  Called in a scalar
context, it returns the parameter list as a tied hash reference.
Changing a key changes the value of the parameter in the underlying
\&\s-1CGI\s0 parameter list.  Called in a list context, it returns the
parameter list as an ordinary hash.  This allows you to read the
contents of the parameter list, but not to change it.
.PP
When using this, the thing you must watch out for are multivalued \s-1CGI\s0
parameters.  Because a hash cannot distinguish between scalar and
list context, multivalued parameters will be returned as a packed
string, separated by the \*(L"\e0\*(R" (null) character.  You must split this
packed string in order to get at the individual values.  This is the
convention introduced long ago by Steve Brenner in his cgi\-lib.pl
module for Perl version 4.
.PP
If you wish to use \fIVars()\fR as a function, import the \fI:cgi\-lib\fR set of
function calls (also see the section on CGI-LIB compatibility).
.Sh "\s-1SAVING\s0 \s-1THE\s0 \s-1STATE\s0 \s-1OF\s0 \s-1THE\s0 \s-1SCRIPT\s0 \s-1TO\s0 A \s-1FILE:\s0"
.IX Subsection "SAVING THE STATE OF THE SCRIPT TO A FILE:"
.Vb 1
\&    $query\->save(\e*FILEHANDLE)
.Ve
.PP
This will write the current state of the form to the provided
filehandle.  You can read it back in by providing a filehandle
to the \fInew()\fR method.  Note that the filehandle can be a file, a pipe,
or whatever!
.PP
The format of the saved file is:
.PP
.Vb 5
\&        NAME1=VALUE1
\&        NAME1=VALUE1\*(Aq
\&        NAME2=VALUE2
\&        NAME3=VALUE3
\&        =
.Ve
.PP
Both name and value are \s-1URL\s0 escaped.  Multi-valued \s-1CGI\s0 parameters are
represented as repeated names.  A session record is delimited by a
single = symbol.  You can write out multiple records and read them
back in with several calls to \fBnew\fR.  You can do this across several
sessions by opening the file in append mode, allowing you to create
primitive guest books, or to keep a history of users' queries.  Here's
a short example of creating multiple session records:
.PP
.Vb 1
\&   use CGI;
\&