fetch.pm

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.

sub _curl_fetch {
    my $self = shift;
    my %hash = @_;

    my ($to);
    my $tmpl = {
        to  => { required => 1, store => \$to }
    };
    check( $tmpl, \%hash ) or return;

    if (my $curl = can_run('curl')) {

        ### these long opts are self explanatory - I like that -jmb
	    my $cmd = [ $curl ];

	    push(@$cmd, '--connect-timeout', $TIMEOUT) if $TIMEOUT;

	    push(@$cmd, '--silent') unless $DEBUG;

        ### curl does the right thing with passive, regardless ###
    	if ($self->scheme eq 'ftp') {
    		push(@$cmd, '--user', "anonymous:$FROM_EMAIL");
    	}

        ### curl doesn't follow 302 (temporarily moved) etc automatically
        ### so we add --location to enable that.
        push @$cmd, '--fail', '--location', '--output', 
                    ### DO NOT quote things for IPC::Run, it breaks stuff.
                    $IPC::Cmd::USE_IPC_RUN
                        ? ($to, $self->uri)
                        : (QUOTE. $to .QUOTE, QUOTE. $self->uri .QUOTE);

        my $captured;
        unless(run( command => $cmd,
                    buffer  => \$captured,
                    verbose => $DEBUG )
        ) {

            return $self->_error(loc("Command failed: %1", $captured || ''));
        }

        return $to;

    } else {
        $METHOD_FAIL->{'curl'} = 1;
        return;
    }
}


### use File::Copy for fetching file:// urls ###
###
### See section 3.10 of RFC 1738 (http://www.faqs.org/rfcs/rfc1738.html)
### Also see wikipedia on file:// (http://en.wikipedia.org/wiki/File://)
###
    
sub _file_fetch {
    my $self = shift;
    my %hash = @_;

    my ($to);
    my $tmpl = {
        to  => { required => 1, store => \$to }
    };
    check( $tmpl, \%hash ) or return;

    
    
    ### prefix a / on unix systems with a file uri, since it would
    ### look somewhat like this:
    ###     file:///home/kane/file
    ### wheras windows file uris for 'c:\some\dir\file' might look like:
    ###     file:///C:/some/dir/file
    ###     file:///C|/some/dir/file
    ### or for a network share '\\host\share\some\dir\file':
    ###     file:////host/share/some/dir/file
    ###    
    ### VMS file uri's for 'DISK$USER:[MY.NOTES]NOTE123456.TXT' might look like:
    ###     file://vms.host.edu/disk$user/my/notes/note12345.txt
    ###
    
    my $path    = $self->path;
    my $vol     = $self->vol;
    my $share   = $self->share;

    my $remote;
    if (!$share and $self->host) {
        return $self->_error(loc( 
            "Currently %1 cannot handle hosts in %2 urls",
            'File::Fetch', 'file://'
        ));            
    }
    
    if( $vol ) {
        $path   = File::Spec->catdir( split /\//, $path );
        $remote = File::Spec->catpath( $vol, $path, $self->file);

    } elsif( $share ) {
        ### win32 specific, and a share name, so we wont bother with File::Spec
        $path   =~ s|/+|\\|g;
        $remote = "\\\\".$self->host."\\$share\\$path";

    } else {
        ### File::Spec on VMS can not currently handle UNIX syntax.
        my $file_class = ON_VMS
            ? 'File::Spec::Unix'
            : 'File::Spec';

        $remote  = $file_class->catfile( $path, $self->file );
    }

    ### File::Copy is littered with 'die' statements :( ###
    my $rv = eval { File::Copy::copy( $remote, $to ) };

    ### something went wrong ###
    if( !$rv or $@ ) {
        return $self->_error(loc("Could not copy '%1' to '%2': %3 %4",
                             $remote, $to, $!, $@));
    }

    return $to;
}

### use /usr/bin/rsync to fetch files
sub _rsync_fetch {
    my $self = shift;
    my %hash = @_;

    my ($to);
    my $tmpl = {
        to  => { required => 1, store => \$to }
    };
    check( $tmpl, \%hash ) or return;

    if (my $rsync = can_run('rsync')) {

        my $cmd = [ $rsync ];

        ### XXX: rsync has no I/O timeouts at all, by default
        push(@$cmd, '--timeout=' . $TIMEOUT) if $TIMEOUT;

        push(@$cmd, '--quiet') unless $DEBUG;

        ### DO NOT quote things for IPC::Run, it breaks stuff.
        push @$cmd, $IPC::Cmd::USE_IPC_RUN
                        ? ($self->uri, $to)
                        : (QUOTE. $self->uri .QUOTE, QUOTE. $to .QUOTE);

        my $captured;
        unless(run( command => $cmd,
                    buffer  => \$captured,
                    verbose => $DEBUG )
        ) {

            return $self->_error(loc("Command %1 failed: %2", 
                "@$cmd" || '', $captured || ''));
        }

        return $to;

    } else {
        $METHOD_FAIL->{'rsync'} = 1;
        return;
    }
}

#################################
#
# Error code
#
#################################

=pod

=head2 $ff->error([BOOL])

Returns the last encountered error as string.
Pass it a true value to get the C<Carp::longmess()> output instead.

=cut

### error handling the way Archive::Extract does it
sub _error {
    my $self    = shift;
    my $error   = shift;
    
    $self->_error_msg( $error );
    $self->_error_msg_long( Carp::longmess($error) );
    
    if( $WARN ) {
        carp $DEBUG ? $self->_error_msg_long : $self->_error_msg;
    }

    return;
}

sub error {
    my $self = shift;
    return shift() ? $self->_error_msg_long : $self->_error_msg;
}


1;

=pod

=head1 HOW IT WORKS

File::Fetch is able to fetch a variety of uris, by using several
external programs and modules.

Below is a mapping of what utilities will be used in what order
for what schemes, if available:

    file    => LWP, file
    http    => LWP, wget, curl, lynx
    ftp     => LWP, Net::FTP, wget, curl, ncftp, ftp
    rsync   => rsync

If you'd like to disable the use of one or more of these utilities
and/or modules, see the C<$BLACKLIST> variable further down.

If a utility or module isn't available, it will be marked in a cache
(see the C<$METHOD_FAIL> variable further down), so it will not be
tried again. The C<fetch> method will only fail when all options are
exhausted, and it was not able to retrieve the file.

A special note about fetching files from an ftp uri:

By default, all ftp connections are done in passive mode. To change
that, see the C<$FTP_PASSIVE> variable further down.

Furthermore, ftp uris only support anonymous connections, so no
named user/password pair can be passed along.

C</bin/ftp> is blacklisted by default; see the C<$BLACKLIST> variable
further down.

=head1 GLOBAL VARIABLES

The behaviour of File::Fetch can be altered by changing the following
global variables:

=head2 $File::Fetch::FROM_EMAIL

This is the email address that will be sent as your anonymous ftp
password.

Default is C<[e-mail]>.

=head2 $File::Fetch::USER_AGENT

This is the useragent as C<LWP> will report it.

Default is C<File::Fetch/$VERSION>.

=head2 $File::Fetch::FTP_PASSIVE

This variable controls whether the environment variable C<FTP_PASSIVE>
and any passive switches to commandline tools will be set to true.

Default value is 1.

Note: When $FTP_PASSIVE is true, C<ncftp> will not be used to fetch
files, since passive mode can only be set interactively for this binary

=head2 $File::Fetch::TIMEOUT

When set, controls the network timeout (counted in seconds).

Default value is 0.

=head2 $File::Fetch::WARN

This variable controls whether errors encountered internally by
C<File::Fetch> should be C<carp>'d or not.

Set to false to silence warnings. Inspect the output of the C<error()>
method manually to see what went wrong.

Defaults to C<true>.

=head2 $File::Fetch::DEBUG

This enables debugging output when calling commandline utilities to
fetch files.
This also enables C<Carp::longmess> errors, instead of the regular
C<carp> errors.

Good for tracking down why things don't work with your particular
setup.

Default is 0.

=head2 $File::Fetch::BLACKLIST

This is an array ref holding blacklisted modules/utilities for fetching
files with.

To disallow the use of, for example, C<LWP> and C<Net::FTP>, you could
set $File::Fetch::BLACKLIST to:

    $File::Fetch::BLACKLIST = [qw|lwp netftp|]

The default blacklist is [qw|ftp|], as C</bin/ftp> is rather unreliable.

See the note on C<MAPPING> below.

=head2 $File::Fetch::METHOD_FAIL

This is a hashref registering what modules/utilities were known to fail
for fetching files (mostly because they weren't installed).

You can reset this cache by assigning an empty hashref to it, or
individually remove keys.

See the note on C<MAPPING> below.

=head1 MAPPING


Here's a quick mapping for the utilities/modules, and their names for
the $BLACKLIST, $METHOD_FAIL and other internal functions.

    LWP         => lwp
    Net::FTP    => netftp
    wget        => wget
    lynx        => lynx
    ncftp       => ncftp
    ftp         => ftp
    curl        => curl
    rsync       => rsync

=head1 FREQUENTLY ASKED QUESTIONS

=head2 So how do I use a proxy with File::Fetch?

C<File::Fetch> currently only supports proxies with LWP::UserAgent.
You will need to set your environment variables accordingly. For
example, to use an ftp proxy:

    $ENV{ftp_proxy} = 'foo.com';

Refer to the LWP::UserAgent manpage for more details.

=head2 I used 'lynx' to fetch a file, but its contents is all wrong!

C<lynx> can only fetch remote files by dumping its contents to C<STDOUT>,
which we in turn capture. If that content is a 'custom' error file
(like, say, a C<404 handler>), you will get that contents instead.

Sadly, C<lynx> doesn't support any options to return a different exit
code on non-C<200 OK> status, giving us no way to tell the difference
between a 'successfull' fetch and a custom error page.

Therefor, we recommend to only use C<lynx> as a last resort. This is 
why it is at the back of our list of methods to try as well.

=head2 Files I'm trying to fetch have reserved characters or non-ASCII characters in them. What do I do?

C<File::Fetch> is relatively smart about things. When trying to write 
a file to disk, it removes the C<query parameters> (see the 
C<output_file> method for details) from the file name before creating
it. In most cases this suffices.

If you have any other characters you need to escape, please install 
the C<URI::Escape> module from CPAN, and pre-encode your URI before
passing it to C<File::Fetch>. You can read about the details of URIs 
and URI encoding here:

  http://www.faqs.org/rfcs/rfc2396.html

=head1 TODO

=over 4

=item Implement $PREFER_BIN

To indicate to rather use commandline tools than modules

=back

=head1 BUG REPORTS

Please report bugs or other issues to E<lt>[e-mail]<gt>.

=head1 AUTHOR

This module by Jos Boumans E<lt>[e-mail]<gt>.

=head1 COPYRIGHT

This library is free software; you may redistribute and/or modify it 
under the same terms as Perl itself.


=cut

# Local variables:
# c-indentation-style: bsd
# c-basic-offset: 4
# indent-tabs-mode: nil
# End:
# vim: expandtab shiftwidth=4: