net::hostent.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.

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.\" ========================================================================
.\"
.IX Title "Net::hostent 3"
.TH Net::hostent 3 "2007-12-18" "perl v5.10.0" "Perl Programmers Reference Guide"
.\" 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"
Net::hostent \- by\-name interface to Perl's built\-in gethost*() functions
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& use Net::hostent;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module's default exports override the core \fIgethostbyname()\fR and
\&\fIgethostbyaddr()\fR functions, replacing them with versions that return
\&\*(L"Net::hostent\*(R" objects.  This object has methods that return the similarly
named structure field name from the C's hostent structure from \fInetdb.h\fR;
namely name, aliases, addrtype, length, and addr_list.  The aliases and
addr_list methods return array reference, the rest scalars.  The addr
method is equivalent to the zeroth element in the addr_list array
reference.
.PP
You may also import all the structure fields directly into your namespace
as regular variables using the :FIELDS import tag.  (Note that this still
overrides your core functions.)  Access these fields as variables named
with a preceding \f(CW\*(C`h_\*(C'\fR.  Thus, \f(CW\*(C`$host_obj\->name()\*(C'\fR corresponds to
\&\f(CW$h_name\fR if you import the fields.  Array references are available as
regular array variables, so for example \f(CW\*(C`@{ $host_obj\->aliases()
}\*(C'\fR would be simply \f(CW@h_aliases\fR.
.PP
The \fIgethost()\fR function is a simple front-end that forwards a numeric
argument to \fIgethostbyaddr()\fR by way of Socket::inet_aton, and the rest
to \fIgethostbyname()\fR.
.PP
To access this functionality without the core overrides,
pass the \f(CW\*(C`use\*(C'\fR an empty import list, and then access
function functions with their full qualified names.
On the other hand, the built-ins are still available
via the \f(CW\*(C`CORE::\*(C'\fR pseudo-package.
.SH "EXAMPLES"
.IX Header "EXAMPLES"
.Vb 2
\& use Net::hostent;
\& use Socket;
\&
\& @ARGV = (\*(Aqnetscape.com\*(Aq) unless @ARGV;
\&
\& for $host ( @ARGV ) {
\&
\&    unless ($h = gethost($host)) {
\&        warn "$0: no such host: $host\en";
\&        next;
\&    }
\&
\&    printf "\en%s is %s%s\en", 
\&            $host, 
\&            lc($h\->name) eq lc($host) ? "" : "*really* ",
\&            $h\->name;
\&
\&    print "\etaliases are ", join(", ", @{$h\->aliases}), "\en"
\&                if @{$h\->aliases};     
\&
\&    if ( @{$h\->addr_list} > 1 ) { 
\&        my $i;
\&        for $addr ( @{$h\->addr_list} ) {
\&            printf "\etaddr #%d is [%s]\en", $i++, inet_ntoa($addr);
\&        } 
\&    } else {
\&        printf "\etaddress is [%s]\en", inet_ntoa($h\->addr);
\&    } 
\&
\&    if ($h = gethostbyaddr($h\->addr)) {
\&        if (lc($h\->name) ne lc($host)) {
\&            printf "\etThat addr reverses to host %s!\en", $h\->name;
\&            $host = $h\->name;
\&            redo;
\&        } 
\&    }
\& }
.Ve
.SH "NOTE"
.IX Header "NOTE"
While this class is currently implemented using the Class::Struct
module to build a struct-like class, you shouldn't rely upon this.
.SH "AUTHOR"
.IX Header "AUTHOR"
Tom Christiansen