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 suEXEC or a \s-1CGI\s0 wrapper program to run your script.  The temporary
file is created with mode 0600 (neither world nor group readable).
.Sp
The temporary directory is selected using the following algorithm:
.Sp
.Vb 2
\&    1. if the current user (e.g. "nobody") has a directory named
\&    "tmp" in its home directory, use that (Unix systems only).
\&
\&    2. if the environment variable TMPDIR exists, use the location
\&    indicated.
\&
\&    3. Otherwise try the locations /usr/tmp, /var/tmp, C:\etemp,
\&    /tmp, /temp, ::Temporary Items, and \eWWW_ROOT.
.Ve
.Sp
Each of these locations is checked that it is a directory and is
writable.  If not, the algorithm tries the next choice.
.Sh "\s-1SPECIAL\s0 \s-1FORMS\s0 \s-1FOR\s0 \s-1IMPORTING\s0 HTML-TAG \s-1FUNCTIONS\s0"
.IX Subsection "SPECIAL FORMS FOR IMPORTING HTML-TAG FUNCTIONS"
Many of the methods generate \s-1HTML\s0 tags.  As described below, tag
functions automatically generate both the opening and closing tags.
For example:
.PP
.Vb 1
\&  print h1(\*(AqLevel 1 Header\*(Aq);
.Ve
.PP
produces
.PP
.Vb 1
\&  <h1>Level 1 Header</h1>
.Ve
.PP
There will be some times when you want to produce the start and end
tags yourself.  In this case, you can use the form start_\fItag_name\fR
and end_\fItag_name\fR, as in:
.PP
.Vb 1
\&  print start_h1,\*(AqLevel 1 Header\*(Aq,end_h1;
.Ve
.PP
With a few exceptions (described below), start_\fItag_name\fR and
end_\fItag_name\fR functions are not generated automatically when you
\&\fIuse \s-1CGI\s0\fR.  However, you can specify the tags you want to generate
\&\fIstart/end\fR functions for by putting an asterisk in front of their
name, or, alternatively, requesting either "start_\fItag_name\fR\*(L" or
\&\*(R"end_\fItag_name\fR" in the import list.
.PP
Example:
.PP
.Vb 1
\&  use CGI qw/:standard *table start_ul/;
.Ve
.PP
In this example, the following functions are generated in addition to
the standard ones:
.IP "1. \fIstart_table()\fR (generates a <table> tag)" 4
.IX Item "1. start_table() (generates a <table> tag)"
.PD 0
.IP "2. \fIend_table()\fR (generates a </table> tag)" 4
.IX Item "2. end_table() (generates a </table> tag)"
.IP "3. \fIstart_ul()\fR (generates a <ul> tag)" 4
.IX Item "3. start_ul() (generates a <ul> tag)"
.IP "4. \fIend_ul()\fR (generates a </ul> tag)" 4
.IX Item "4. end_ul() (generates a </ul> tag)"
.PD
.SH "GENERATING DYNAMIC DOCUMENTS"
.IX Header "GENERATING DYNAMIC DOCUMENTS"
Most of \s-1CGI\s0.pm's functions deal with creating documents on the fly.
Generally you will produce the \s-1HTTP\s0 header first, followed by the
document itself.  \s-1CGI\s0.pm provides functions for generating \s-1HTTP\s0
headers of various types as well as for generating \s-1HTML\s0.  For creating
\&\s-1GIF\s0 images, see the \s-1GD\s0.pm module.
.PP
Each of these functions produces a fragment of \s-1HTML\s0 or \s-1HTTP\s0 which you
can print out directly so that it displays in the browser window,
append to a string, or save to a file for later use.
.Sh "\s-1CREATING\s0 A \s-1STANDARD\s0 \s-1HTTP\s0 \s-1HEADER:\s0"
.IX Subsection "CREATING A STANDARD HTTP HEADER:"
Normally the first thing you will do in any \s-1CGI\s0 script is print out an
\&\s-1HTTP\s0 header.  This tells the browser what type of document to expect,
and gives other optional information, such as the language, expiration
date, and whether to cache the document.  The header can also be
manipulated for special purposes, such as server push and pay per view
pages.
.PP
.Vb 1
\&        print header;
\&
\&             \-or\-
\&
\&        print header(\*(Aqimage/gif\*(Aq);
\&
\&             \-or\-
\&
\&        print header(\*(Aqtext/html\*(Aq,\*(Aq204 No response\*(Aq);
\&
\&             \-or\-
\&
\&        print header(\-type=>\*(Aqimage/gif\*(Aq,
\&                             \-nph=>1,
\&                             \-status=>\*(Aq402 Payment required\*(Aq,
\&                             \-expires=>\*(Aq+3d\*(Aq,
\&                             \-cookie=>$cookie,
\&                             \-charset=>\*(Aqutf\-7\*(Aq,
\&                             \-attachment=>\*(Aqfoo.gif\*(Aq,
\&                             \-Cost=>\*(Aq$2.00\*(Aq);
.Ve
.PP
\&\fIheader()\fR returns the Content-type: header.  You can provide your own
\&\s-1MIME\s0 type if you choose, otherwise it defaults to text/html.  An
optional second parameter specifies the status code and a human-readable
message.  For example, you can specify 204, \*(L"No response\*(R" to create a
script that tells the browser to do nothing at all.
.PP
The last example shows the named argument style for passing arguments
to the \s-1CGI\s0 methods using named parameters.  Recognized parameters are
\&\fB\-type\fR, \fB\-status\fR, \fB\-expires\fR, and \fB\-cookie\fR.  Any other named
parameters will be stripped of their initial hyphens and turned into
header fields, allowing you to specify any \s-1HTTP\s0 header you desire.
Internal underscores will be turned into hyphens:
.PP
.Vb 1
\&    print header(\-Content_length=>3002);
.Ve
.PP
Most browsers will not cache the output from \s-1CGI\s0 scripts.  Every time
the browser reloads the page, the script is invoked anew.  You can
change this behavior with the \fB\-expires\fR parameter.  When you specify
an absolute or relative expiration interval with this parameter, some
browsers and proxy servers will cache the script's output until the
indicated expiration date.  The following forms are all valid for the
\&\-expires field:
.PP
.Vb 8
\&        +30s                              30 seconds from now
\&        +10m                              ten minutes from now
\&        +1h                               one hour from now
\&        \-1d                               yesterday (i.e. "ASAP!")
\&        now                               immediately
\&        +3M                               in three months
\&        +10y                              in ten years time
\&        Thursday, 25\-Apr\-1999 00:40:33 GMT  at the indicated time & date
.Ve
.PP
The \fB\-cookie\fR parameter generates a header that tells the browser to provide
a \*(L"magic cookie\*(R" during all subsequent transactions with your script.
Netscape cookies have a special format that includes interesting attributes
such as expiration time.  Use the \fIcookie()\fR method to create and retrieve
session cookies.
.PP
The \fB\-nph\fR parameter, if set to a true value, will issue the correct
headers to work with a \s-1NPH\s0 (no-parse-header) script.  This is important
to use with certain servers that expect all their scripts to be \s-1NPH\s0.
.PP
The \fB\-charset\fR parameter can be used to control the character set
sent to the browser.  If not provided, defaults to \s-1ISO\-8859\-1\s0.  As a
side effect, this sets the \fIcharset()\fR method as well.
.PP
The \fB\-attachment\fR parameter can be used to turn the page into an
attachment.  Instead of displaying the page, some browsers will prompt
the user to save it to disk.  The value of the argument is the
suggested name for the saved file.  In order for this to work, you may
have to set the \fB\-type\fR to \*(L"application/octet\-stream\*(R".
.PP
The \fB\-p3p\fR parameter will add a P3P tag to the outgoing header.  The
parameter can be an arrayref or a space-delimited string of P3P tags.
For example:
.PP
.Vb 2
\&   print header(\-p3p=>[qw(CAO DSP LAW CURa)]);
\&   print header(\-p3p=>\*(AqCAO DSP LAW CURa\*(Aq);
.Ve
.PP
In either case, the outgoing header will be formatted as:
.PP
.Vb 1
\&  P3P: policyref="/w3c/p3p.xml" cp="CAO DSP LAW CURa"
.Ve
.Sh "\s-1GENERATING\s0 A \s-1REDIRECTION\s0 \s-1HEADER\s0"
.IX Subsection "GENERATING A REDIRECTION HEADER"
.Vb 1
\&   print redirect(\*(Aqhttp://somewhere.else/in/movie/land\*(Aq);
.Ve
.PP
Sometimes you don't want to produce a document yourself, but simply
redirect the browser elsewhere, perhaps choosing a \s-1URL\s0 based on the
time of day or the identity of the user.
.PP
The \fIredirect()\fR function redirects the browser to a different \s-1URL\s0.  If
you use redirection like this, you should \fBnot\fR print out a header as
well.
.PP
You should always use full URLs (including the http: or ftp: part) in
redirection requests.  Relative URLs will not work correctly.
.PP
You can also use named arguments:
.PP
.Vb 3
\&    print redirect(\-uri=>\*(Aqhttp://somewhere.else/in/movie/land\*(Aq,
\&                           \-nph=>1,
\&                           \-status=>301);
.Ve
.PP
The \fB\-nph\fR parameter, if set to a true value, will issue the correct
headers to work with a \s-1NPH\s0 (no-parse-header) script.  This is important
to use with certain servers, such as Microsoft \s-1IIS\s0, which
expect all their scripts to be \s-1NPH\s0.
.PP
The \fB\-status\fR parameter will set the status of the redirect.  \s-1HTTP\s0
defines three different possible redirection status codes:
.PP
.Vb 3
\&     301 Moved Permanently
\&     302 Found
\&     303 See Other
.Ve
.PP
The default if not specified is 302, which means \*(L"moved temporarily.\*(R"
You may change the status to another status code if you wish.  Be
advised that changing the status to anything other than 301, 302 or
303 will probably break redirection.
.Sh "\s-1CREATING\s0 \s-1THE\s0 \s-1HTML\s0 \s-1DOCUMENT\s0 \s-1HEADER\s0"
.IX Subsection "CREATING THE HTML DOCUMENT HEADER"
.Vb 8
\&   print start_html(\-title=>\*(AqSecrets of the Pyramids\*(Aq,
\&                            \-author=>\*([e-mail]\*(Aq,
\&                            \-base=>\*(Aqtrue\*(Aq,
\&                            \-target=>\*(Aq_blank\*(Aq,
\&                            \-meta=>{\*(Aqkeywords\*(Aq=>\*(Aqpharaoh secret mummy\*(Aq,
\&                                    \*(Aqcopyright\*(Aq=>\*(Aqcopyright 1996 King Tut\*(Aq},
\&                            \-style=>{\*(Aqsrc\*(Aq=>\*(Aq/styles/style1.css\*(Aq},
\&                            \-BGCOLOR=>\*(Aqblue\*(Aq);
.Ve
.PP
After creating the \s-1HTTP\s0 header, most \s-1CGI\s0 scripts will start writing
out an \s-1HTML\s0 document.  The \fIstart_html()\fR routine creates the top of the
page, along with a lot of optional information that controls the
page's appearance and behavior.
.PP
This method returns a canned \s-1HTML\s0 header and the opening <body> tag.
All parameters are optional.  In the named parameter form, recognized
parameters are \-title, \-author, \-base, \-xbase, \-dtd, \-lang and \-target
(see below for the explanation).  Any additional parameters you
provide, such as the Netscape unofficial \s-1BGCOLOR\s0 attribute, are added
to the <body> tag.  Additional parameters must be proceeded by a
hyphen.
.PP
The argument \fB\-xbase\fR allows you to provide an \s-1HREF\s0 for the <base> tag
different from the current location, as in
.PP
.Vb 1
\&    \-xbase=>"http://home.mcom.com/"
.Ve
.PP
All relative links will be interpreted relative to this tag.
.PP
The argument \fB\-target\fR allows you to provide a default target frame
for all the links and fill-out forms on the page.  \fBThis is a
non-standard \s-1HTTP\s0 feature which only works with Netscape browsers!\fR
See the Netscape documentation on frames for details of how to
manipulate this.
.PP
.Vb 1
\&    \-target=>"answer_window"
.Ve
.PP
All relative links will be interpreted relative to this tag.
You add arbitrary meta information to the header with the \fB\-meta\fR
argument.  This argument expects a reference to an associative array
containing name/value pairs of meta information.  These will be turned
into a series of header <meta> tags that look something like this:
.PP
.Vb 2
\&    <meta name="keywords" content="pharaoh secret mummy">
\&    <meta name="description" content="copyright 1996 King Tut">
.Ve
.PP
To create an HTTP-EQUIV type of <meta> tag, use \fB\-head\fR, described
below.
.PP
The \fB\-style\fR argument is used to incorporate cascading stylesheets
into your code.  See the section on \s-1CASCADING\s0 \s-1STYLESHEETS\s0 for more
information.
.PP
The \fB\-lang\fR argument is used to incorporate a language attribute into
the <html> tag.  For example:
.PP
.Vb 1
\&    print $q\->start_html(\-lang=>\*(Aqfr\-CA\*(Aq);
.Ve
.PP
The default if not specified is \*(L"en-US\*(R" for \s-1US\s0 English, unless the 
\&\-dtd parameter specifies an \s-1HTML\s0 2.0 or 3.2 \s-1DTD\s0, in which case the
lang attribute is left off.  You can force the lang attribute to left
off in other cases by passing an empty string (\-lang=>'').
.PP
The \fB\-encoding\fR argument can be used to specify the character set for
\&\s-1XHTML\s0.  It defaults to iso\-8859\-1 if not specified.
.PP
The \fB\-declare_xml\fR argument, when used in conjunction with \s-1XHTML\s0,
will put a <?xml> declaration at the top of the \s-1HTML\s0 header. The sole
purpose of this declaration is to declare the character set
encoding. In the absence of \-declare_xml, the output \s-1HTML\s0 will contain
a <meta> tag that specifies the encoding, allowing the \s-1HTML\s0 to pass
most validators.  The default for \-declare_xml is false.
.PP
You can place other arbitrary \s-1HTML\s0 elements to the <head> section with the
\&\fB\-head\fR tag.  For example, to place the rarely-used <link> element in the
head section, use this:
.PP
.Vb 2
\&    print start_html(\-head=>Link({\-rel=>\*(Aqnext\*(Aq,
\&                                  \-href=>\*(Aqhttp://www.capricorn.com/s2.html\*(Aq}));
.Ve
.PP
To incorporate multiple \s-1HTML\s0 elements into the <head> section, just pass an
array reference:
.PP
.Vb 7
\&    print start_html(\-head=>[ 
\&                             Link({\-rel=>\*(Aqnext\*(Aq,
\&                                   \-href=>\*(Aqhttp://www.capricorn.com/s2.html\*(Aq}),
\&                             Link({\-rel=>\*(Aqprevious\*(Aq,
\&                                   \-href=>\*(Aqhttp://www.capricorn.com/s1.html\*(Aq})