proxyserver.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.

#	$Header: /home/timbo/dbi/lib/DBI/RCS/ProxyServer.pm,v 11.9 2003/05/14 11:08:17 timbo Exp $
# -*- perl -*-
#
#   DBI::ProxyServer - a proxy server for DBI drivers
#
#   Copyright (c) 1997  Jochen Wiedmann
#
#   The DBD::Proxy module is free software; you can redistribute it and/or
#   modify it under the same terms as Perl itself. In particular permission
#   is granted to Tim Bunce for distributing this as a part of the DBI.
#
#
#   Author: Jochen Wiedmann
#           Am Eisteich 9
#           72555 Metzingen
#           Germany
#
#           Email: [e-mail]
#           Phone: [phone]
#
#
##############################################################################


require 5.004;
use strict;

use RPC::PlServer 0.2001;
# require DBI; # deferred till AcceptVersion() to aid threading
require Config;


package DBI::ProxyServer;



############################################################################
#
#   Constants
#
############################################################################

use vars qw($VERSION @ISA);

$VERSION = "0.3005";
@ISA = qw(RPC::PlServer DBI);


# Most of the options below are set to default values, we note them here
# just for the sake of documentation.
my %DEFAULT_SERVER_OPTIONS;
{
    my $o = \%DEFAULT_SERVER_OPTIONS;
    $o->{'chroot'}     = undef,		# To be used in the initfile,
    					# after loading the required
    					# DBI drivers.
    $o->{'clients'} =
	[ { 'mask' => '.*',
	    'accept' => 1,
	    'cipher' => undef
	    }
	  ];
    $o->{'configfile'} = '/etc/dbiproxy.conf' if -f '/etc/dbiproxy.conf';
    $o->{'debug'}      = 0;
    $o->{'facility'}   = 'daemon';
    $o->{'group'}      = undef;
    $o->{'localaddr'}  = undef;		# Bind to any local IP number
    $o->{'localport'}  = undef;         # Must set port number on the
					# command line.
    $o->{'logfile'}    = undef;         # Use syslog or EventLog.

    # XXX don't restrict methods that can be called (trust users once connected)
    $o->{'XXX_methods'}    = {
	'DBI::ProxyServer' => {
	    'Version' => 1,
	    'NewHandle' => 1,
	    'CallMethod' => 1,
	    'DestroyHandle' => 1
	    },
	'DBI::ProxyServer::db' => {
	    'prepare' => 1,
	    'commit' => 1,
	    'rollback' => 1,
	    'STORE' => 1,
	    'FETCH' => 1,
	    'func' => 1,
	    'quote' => 1,
	    'type_info_all' => 1,
	    'table_info' => 1,
	    'disconnect' => 1,
	    },
	'DBI::ProxyServer::st' => {
	    'execute' => 1,
	    'STORE' => 1,
	    'FETCH' => 1,
	    'func' => 1,
	    'fetch' => 1,
	    'finish' => 1
	    }
    };
    if ($Config::Config{'usethreads'} eq 'define') {
	$o->{'mode'} = 'threads';
    } elsif ($Config::Config{'d_fork'} eq 'define') {
	$o->{'mode'} = 'fork';
    } else {
	$o->{'mode'} = 'single';
    }
    # No pidfile by default, configuration must provide one if needed
    $o->{'pidfile'}    = 'none';
    $o->{'user'}       = undef;
};


############################################################################
#
#   Name:    Version
#
#   Purpose: Return version string
#
#   Inputs:  $class - This class
#
#   Result:  Version string; suitable for printing by "--version"
#
############################################################################

sub Version {
    my $version = $DBI::ProxyServer::VERSION;
    "DBI::ProxyServer $version, Copyright (C) 1998, Jochen Wiedmann";
}


############################################################################
#
#   Name:    AcceptApplication
#
#   Purpose: Verify DBI DSN
#
#   Inputs:  $self - This instance
#            $dsn - DBI dsn
#
#   Returns: TRUE for a valid DSN, FALSE otherwise
#
############################################################################

sub AcceptApplication {
    my $self = shift; my $dsn = shift;
    $dsn =~ /^dbi:\w+:/i;
}


############################################################################
#
#   Name:    AcceptVersion
#
#   Purpose: Verify requested DBI version
#
#   Inputs:  $self - Instance
#            $version - DBI version being requested
#
#   Returns: TRUE for ok, FALSE otherwise
#
############################################################################

sub AcceptVersion {
    my $self = shift; my $version = shift;
    require DBI;
    DBI::ProxyServer->init_rootclass();
    $DBI::VERSION >= $version;
}


############################################################################
#
#   Name:    AcceptUser
#
#   Purpose: Verify user and password by connecting to the client and
#            creating a database connection
#
#   Inputs:  $self - Instance
#            $user - User name
#            $password - Password
#
############################################################################

sub AcceptUser {
    my $self = shift; my $user = shift; my $password = shift;
    return 0 if (!$self->SUPER::AcceptUser($user, $password));
    my $dsn = $self->{'application'};
    $self->Debug("Connecting to $dsn as $user");
    local $ENV{DBI_AUTOPROXY} = ''; # :-)
    $self->{'dbh'} = eval {
        DBI::ProxyServer->connect($dsn, $user, $password,
				  { 'PrintError' => 0, 
				    'Warn' => 0,
				    'RaiseError' => 1,
				    'HandleError' => sub {
				        my $err = $_[1]->err;
					my $state = $_[1]->state || '';
					$_[0] .= " [err=$err,state=$state]";
					return 0;
				    } })
    };
    if ($@) {
	$self->Error("Error while connecting to $dsn as $user: $@");
	return 0;
    }
    [1, $self->StoreHandle($self->{'dbh'}) ];
}


sub CallMethod {
    my $server = shift;
    my $dbh = $server->{'dbh'};
    # We could store the private_server attribute permanently in
    # $dbh. However, we'd have a reference loop in that case and
    # I would be concerned about garbage collection. :-(
    $dbh->{'private_server'} = $server;
    $server->Debug("CallMethod: => " . join(",", @_));
    my @result = eval { $server->SUPER::CallMethod(@_) };
    my $msg = $@;
    undef $dbh->{'private_server'};
    if ($msg) {
	$server->Debug("CallMethod died with: $@");
	die $msg;
    } else {
	$server->Debug("CallMethod: <= " . join(",", @result));
    }
    @result;
}


sub main {
    my $server = DBI::ProxyServer->new(\%DEFAULT_SERVER_OPTIONS, \@_);
    $server->Bind();
}


############################################################################
#
#   The DBI part of the proxyserver is implemented as a DBI subclass.
#   Thus we can reuse some of the DBI methods and overwrite only
#   those that need additional handling.
#
############################################################################

package DBI::ProxyServer::dr;

@DBI::ProxyServer::dr::ISA = qw(DBI::dr);


package DBI::ProxyServer::db;

@DBI::ProxyServer::db::ISA = qw(DBI::db);

sub prepare {
    my($dbh, $statement, $attr, $params, $proto_ver) = @_;
    my $server = $dbh->{'private_server'};
    if (my $client = $server->{'client'}) {
	if ($client->{'sql'}) {
	    if ($statement =~ /^\s*(\S+)/) {
		my $st = $1;
		if (!($statement = $client->{'sql'}->{$st})) {
		    die "Unknown SQL query: $st";
		}
	    } else {
		die "Cannot parse restricted SQL statement: $statement";
	    }
	}
    }
    my $sth = $dbh->SUPER::prepare($statement, $attr);
    my $handle = $server->StoreHandle($sth);

    if ( $proto_ver and $proto_ver > 1 ) {
      $sth->{private_proxyserver_described} = 0;
      return $handle;

    } else {
      # The difference between the usual prepare and ours is that we implement
      # a combined prepare/execute. The DBD::Proxy driver doesn't call us for
      # prepare. Only if an execute happens, then we are called with method
      # "prepare". Further execute's are called as "execute".
      my @result = $sth->execute($params);
      my ($NAME, $TYPE);
      my $NUM_OF_FIELDS = $sth->{NUM_OF_FIELDS};
      if ($NUM_OF_FIELDS) {	# is a SELECT
	$NAME = $sth->{NAME};
	$TYPE = $sth->{TYPE};
      }
      ($handle, $NUM_OF_FIELDS, $sth->{'NUM_OF_PARAMS'},
       $NAME, $TYPE, @result);
    }
}

sub table_info {
    my $dbh = shift;
    my $sth = $dbh->SUPER::table_info();
    my $numFields = $sth->{'NUM_OF_FIELDS'};
    my $names = $sth->{'NAME'};
    my $types = $sth->{'TYPE'};

    # We wouldn't need to send all the rows at this point, instead we could
    # make use of $rsth->fetch() on the client as usual.
    # The problem is that some drivers (namely DBD::ExampleP, DBD::mysql and
    # DBD::mSQL) are returning foreign sth's here, thus an instance of
    # DBI::st and not DBI::ProxyServer::st. We could fix this by permitting
    # the client to execute method DBI::st, but I don't like this.
    my @rows;
    while (my ($row) = $sth->fetch()) {
        last unless defined $row;
	push(@rows, [@$row]);
    }
    ($numFields, $names, $types, @rows);
}


package DBI::ProxyServer::st;

@DBI::ProxyServer::st::ISA = qw(DBI::st);

sub execute {
    my $sth = shift; my $params = shift; my $proto_ver = shift;
    my @outParams;
    if ($params) {
	for (my $i = 0;  $i < @$params;) {
	    my $param = $params->[$i++];
	    if (!ref($param)) {
		$sth->bind_param($i, $param);
	    }
	    else {	
		if (!ref(@$param[0])) {#It's not a reference
		    $sth->bind_param($i, @$param);
		}
		else {
		    $sth->bind_param_inout($i, @$param);
		    my $ref = shift @$param;
		    push(@outParams, $ref);
		}
	    }
	}
    }
    my $rows = $sth->SUPER::execute();
    if ( $proto_ver and $proto_ver > 1 and not $sth->{private_proxyserver_described} ) {
      my ($NAME, $TYPE);
      my $NUM_OF_FIELDS = $sth->{NUM_OF_FIELDS};
      if ($NUM_OF_FIELDS) {	# is a SELECT
	$NAME = $sth->{NAME};
	$TYPE = $sth->{TYPE};
      }
      $sth->{private_proxyserver_described} = 1;
      # First execution, we ship back description.
      return ($rows, $NUM_OF_FIELDS, $sth->{'NUM_OF_PARAMS'}, $NAME, $TYPE, @outParams);
    }
    ($rows, @outParams);
}

sub fetch {
    my $sth = shift; my $numRows = shift || 1;
    my($ref, @rows);
    while ($numRows--  &&  ($ref = $sth->SUPER::fetch())) {
	push(@rows, [@$ref]);
    }
    @rows;
}


1;


__END__

=head1 NAME

DBI::ProxyServer - a server for the DBD::Proxy driver

=head1 SYNOPSIS

    use DBI::ProxyServer;
    DBI::ProxyServer::main(@ARGV);

=head1 DESCRIPTION

DBI::Proxy Server is a module for implementing a proxy for the DBI proxy
driver, DBD::Proxy. It allows access to databases over the network if the
DBMS does not offer networked operations. But the proxy server might be
usefull for you, even if you have a DBMS with integrated network
functionality: It can be used as a DBI proxy in a firewalled environment.

DBI::ProxyServer runs as a daemon on the machine with the DBMS or on the
firewall. The client connects to the agent using the DBI driver DBD::Proxy,
thus in the exactly same way than using DBD::mysql, DBD::mSQL or any other
DBI driver.

The agent is implemented as a RPC::PlServer application. Thus you have
access to all the possibilities of this module, in particular encryption
and a similar configuration file. DBI::ProxyServer adds the possibility of
query restrictions: You can define a set of queries that a client may
execute and restrict access to those. (Requires a DBI driver that supports
parameter binding.) See L</CONFIGURATION FILE>.

The provided driver script, L<dbiproxy>, may either be used as it is or
used as the basis for a local version modified to meet your needs.

=head1 OPTIONS

When calling the DBI::ProxyServer::main() function, you supply an
array of options. These options are parsed by the Getopt::Long module.
The ProxyServer inherits all of RPC::PlServer's and hence Net::Daemon's
options and option handling, in particular the ability to read
options from either the command line or a config file. See
L<RPC::PlServer>. See L<Net::Daemon>. Available options include

=over 4

=item I<chroot> (B<--chroot=dir>)

(UNIX only)  After doing a bind(), change root directory to the given
directory by doing a chroot(). This is usefull for security, but it
restricts the environment a lot. For example, you need to load DBI
drivers in the config file or you have to create hard links to Unix
sockets, if your drivers are using them. For example, with MySQL, a
config file might contain the following lines:

    my $rootdir = '/var/dbiproxy';
    my $unixsockdir = '/tmp';
    my $unixsockfile = 'mysql.sock';
    foreach $dir ($rootdir, "$rootdir$unixsockdir") {
	mkdir 0755, $dir;
    }
    link("$unixsockdir/$unixsockfile",
	 "$rootdir$unixsockdir/$unixsockfile");
    require DBD::mysql;

    {
	'chroot' => $rootdir,
	...
    }

If you don't know chroot(), think of an FTP server where you can see a
certain directory tree only after logging in. See also the --group and
--user options.

=item I<clients>