syslog.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 connect_tcp {
    my ($errs) = @_;

    my $tcp = getprotobyname('tcp');
    if (!defined $tcp) {
	push @$errs, "getprotobyname failed for tcp";
	return 0;
    }

    my $syslog = getservbyname('syslog', 'tcp');
    $syslog = getservbyname('syslogng', 'tcp') unless defined $syslog;
    if (!defined $syslog) {
	push @$errs, "getservbyname failed for syslog/tcp and syslogng/tcp";
	return 0;
    }

    my $addr;
    if (defined $host) {
        $addr = inet_aton($host);
        if (!$addr) {
	    push @$errs, "can't lookup $host";
	    return 0;
	}
    } else {
        $addr = INADDR_LOOPBACK;
    }
    $addr = sockaddr_in($syslog, $addr);

    if (!socket(SYSLOG, AF_INET, SOCK_STREAM, $tcp)) {
	push @$errs, "tcp socket: $!";
	return 0;
    }

    setsockopt(SYSLOG, SOL_SOCKET, SO_KEEPALIVE, 1);
    if (eval { IPPROTO_TCP() }) {
        # These constants don't exist in 5.005. They were added in 1999
        setsockopt(SYSLOG, IPPROTO_TCP(), TCP_NODELAY(), 1);
    }
    $@ = "";
    if (!connect(SYSLOG, $addr)) {
	push @$errs, "tcp connect: $!";
	return 0;
    }

    $syslog_send = \&_syslog_send_socket;

    return 1;
}

sub connect_udp {
    my ($errs) = @_;

    my $udp = getprotobyname('udp');
    if (!defined $udp) {
	push @$errs, "getprotobyname failed for udp";
	return 0;
    }

    my $syslog = getservbyname('syslog', 'udp');
    if (!defined $syslog) {
	push @$errs, "getservbyname failed for syslog/udp";
	return 0;
    }

    my $addr;
    if (defined $host) {
        $addr = inet_aton($host);
        if (!$addr) {
	    push @$errs, "can't lookup $host";
	    return 0;
	}
    } else {
        $addr = INADDR_LOOPBACK;
    }
    $addr = sockaddr_in($syslog, $addr);

    if (!socket(SYSLOG, AF_INET, SOCK_DGRAM, $udp)) {
	push @$errs, "udp socket: $!";
	return 0;
    }
    if (!connect(SYSLOG, $addr)) {
	push @$errs, "udp connect: $!";
	return 0;
    }

    # We want to check that the UDP connect worked. However the only
    # way to do that is to send a message and see if an ICMP is returned
    _syslog_send_socket("");
    if (!connection_ok()) {
	push @$errs, "udp connect: nobody listening";
	return 0;
    }

    $syslog_send = \&_syslog_send_socket;

    return 1;
}

sub connect_stream {
    my ($errs) = @_;
    # might want syslog_path to be variable based on syslog.h (if only
    # it were in there!)
    $syslog_path = '/dev/conslog' unless defined $syslog_path; 
    if (!-w $syslog_path) {
	push @$errs, "stream $syslog_path is not writable";
	return 0;
    }
    if (!sysopen(SYSLOG, $syslog_path, 0400, O_WRONLY)) {
	push @$errs, "stream can't open $syslog_path: $!";
	return 0;
    }
    $syslog_send = \&_syslog_send_stream;
    return 1;
}

sub connect_pipe {
    my ($errs) = @_;

    $syslog_path ||= &_PATH_LOG || "/dev/log";

    if (not -w $syslog_path) {
        push @$errs, "$syslog_path is not writable";
        return 0;
    }

    if (not open(SYSLOG, ">$syslog_path")) {
        push @$errs, "can't write to $syslog_path: $!";
        return 0;
    }

    $syslog_send = \&_syslog_send_pipe;

    return 1;
}

sub connect_unix {
    my ($errs) = @_;

    $syslog_path ||= _PATH_LOG() if length _PATH_LOG();

    if (not defined $syslog_path) {
        push @$errs, "_PATH_LOG not available in syslog.h and no user-supplied socket path";
	return 0;
    }

    if (not (-S $syslog_path or -c _)) {
        push @$errs, "$syslog_path is not a socket";
	return 0;
    }

    my $addr = sockaddr_un($syslog_path);
    if (!$addr) {
	push @$errs, "can't locate $syslog_path";
	return 0;
    }
    if (!socket(SYSLOG, AF_UNIX, SOCK_STREAM, 0)) {
        push @$errs, "unix stream socket: $!";
	return 0;
    }

    if (!connect(SYSLOG, $addr)) {
        if (!socket(SYSLOG, AF_UNIX, SOCK_DGRAM, 0)) {
	    push @$errs, "unix dgram socket: $!";
	    return 0;
	}
        if (!connect(SYSLOG, $addr)) {
	    push @$errs, "unix dgram connect: $!";
	    return 0;
	}
    }

    $syslog_send = \&_syslog_send_socket;

    return 1;
}

sub connect_native {
    my ($errs) = @_;
    my $logopt = 0;

    # reconstruct the numeric equivalent of the options
    for my $opt (keys %options) {
        $logopt += xlate($opt) if $options{$opt}
    }

    eval { openlog_xs($ident, $logopt, xlate($facility)) };
    if ($@) {
        push @$errs, $@;
        return 0;
    }

    $syslog_send = \&_syslog_send_native;

    return 1;
}

sub connect_eventlog {
    my ($errs) = @_;

    $syslog_xobj = Sys::Syslog::Win32::_install();
    $syslog_send = \&Sys::Syslog::Win32::_syslog_send;

    return 1;
}

sub connect_console {
    my ($errs) = @_;
    if (!-w '/dev/console') {
	push @$errs, "console is not writable";
	return 0;
    }
    $syslog_send = \&_syslog_send_console;
    return 1;
}

# To test if the connection is still good, we need to check if any
# errors are present on the connection. The errors will not be raised
# by a write. Instead, sockets are made readable and the next read
# would cause the error to be returned. Unfortunately the syslog 
# 'protocol' never provides anything for us to read. But with 
# judicious use of select(), we can see if it would be readable...
sub connection_ok {
    return 1 if defined $current_proto and (
        $current_proto eq 'native' or $current_proto eq 'console'
        or $current_proto eq 'eventlog'
    );

    my $rin = '';
    vec($rin, fileno(SYSLOG), 1) = 1;
    my $ret = select $rin, undef, $rin, 0.25;
    return ($ret ? 0 : 1);
}

sub disconnect_log {
    $connected = 0;
    $syslog_send = undef;

    if (defined $current_proto and $current_proto eq 'native') {
        closelog_xs();
        return 1;
    }
    elsif (defined $current_proto and $current_proto eq 'eventlog') {
        $syslog_xobj->Close();
        return 1;
    }

    return close SYSLOG;
}

1;

__END__

=head1 NAME

Sys::Syslog - Perl interface to the UNIX syslog(3) calls

=head1 VERSION

Version 0.22

=head1 SYNOPSIS

    use Sys::Syslog;                          # all except setlogsock(), or:
    use Sys::Syslog qw(:DEFAULT setlogsock);  # default set, plus setlogsock()
    use Sys::Syslog qw(:standard :macros);    # standard functions, plus macros

    openlog $ident, $logopt, $facility;       # don't forget this
    syslog $priority, $format, @args;
    $oldmask = setlogmask $mask_priority;
    closelog;


=head1 DESCRIPTION

C<Sys::Syslog> is an interface to the UNIX C<syslog(3)> program.
Call C<syslog()> with a string priority and a list of C<printf()> args
just like C<syslog(3)>.

You can find a kind of FAQ in L<"THE RULES OF SYS::SYSLOG">.  Please read 
it before coding, and again before asking questions. 


=head1 EXPORTS

C<Sys::Syslog> exports the following C<Exporter> tags: 

=over 4

=item *

C<:standard> exports the standard C<syslog(3)> functions: 

    openlog closelog setlogmask syslog

=item *

C<:extended> exports the Perl specific functions for C<syslog(3)>: 

    setlogsock

=item *

C<:macros> exports the symbols corresponding to most of your C<syslog(3)> 
macros and the C<LOG_UPTO()> and C<LOG_MASK()> functions. 
See L<"CONSTANTS"> for the supported constants and their meaning. 

=back

By default, C<Sys::Syslog> exports the symbols from the C<:standard> tag. 


=head1 FUNCTIONS

=over 4

=item B<openlog($ident, $logopt, $facility)>

Opens the syslog.
C<$ident> is prepended to every message.  C<$logopt> contains zero or
more of the options detailed below.  C<$facility> specifies the part 
of the system to report about, for example C<LOG_USER> or C<LOG_LOCAL0>:
see L<"Facilities"> for a list of well-known facilities, and your 
C<syslog(3)> documentation for the facilities available in your system. 
Check L<"SEE ALSO"> for useful links. Facility can be given as a string 
or a numeric macro. 

This function will croak if it can't connect to the syslog daemon.

Note that C<openlog()> now takes three arguments, just like C<openlog(3)>.

B<You should use C<openlog()> before calling C<syslog()>.>

B<Options>

=over 4

=item *

C<cons> - This option is ignored, since the failover mechanism will drop 
down to the console automatically if all other media fail.

=item *

C<ndelay> - Open the connection immediately (normally, the connection is
opened when the first message is logged).

=item *

C<nofatal> - When set to true, C<openlog()> and C<syslog()> will only 
emit warnings instead of dying if the connection to the syslog can't 
be established. 

=item *

C<nowait> - Don't wait for child processes that may have been created 
while logging the message.  (The GNU C library does not create a child
process, so this option has no effect on Linux.)

=item *

C<perror> - Write the message to standard error output as well to the
system log.

=item *

C<pid> - Include PID with each message.

=back

B<Examples>

Open the syslog with options C<ndelay> and C<pid>, and with facility C<LOCAL0>: 

    openlog($name, "ndelay,pid", "local0");

Same thing, but this time using the macro corresponding to C<LOCAL0>: 

    openlog($name, "ndelay,pid", LOG_LOCAL0);


=item B<syslog($priority, $message)>

=item B<syslog($priority, $format, @args)>

If C<$priority> permits, logs C<$message> or C<sprintf($format, @args)>
with the addition that C<%m> in $message or C<$format> is replaced with
C<"$!"> (the latest error message). 

C<$priority> can specify a level, or a level and a facility.  Levels and 
facilities can be given as strings or as macros.  When using the C<eventlog>
mechanism, priorities C<DEBUG> and C<INFO> are mapped to event type 
C<informational>, C<NOTICE> and C<WARNIN> to C<warning> and C<ERR> to 
C<EMERG> to C<error>.

If you didn't use C<openlog()> before using C<syslog()>, C<syslog()> will 
try to guess the C<$ident> by extracting the shortest prefix of 
C<$format> that ends in a C<":">.

B<Examples>

    syslog("info", $message);           # informational level
    syslog(LOG_INFO, $message);         # informational level

    syslog("info|local0", $message);        # information level, Local0 facility
    syslog(LOG_INFO|LOG_LOCAL0, $message);  # information level, Local0 facility

=over 4

=item B<Note>

C<Sys::Syslog> version v0.07 and older passed the C<$message> as the 
formatting string to C<sprintf()> even when no formatting arguments
were provided.  If the code calling C<syslog()> might execute with 
older versions of this module, make sure to call the function as
C<syslog($priority, "%s", $message)> instead of C<syslog($priority,
$message)>.  This protects against hostile formatting sequences that
might show up if $message contains tainted data.

=back


=item B<setlogmask($mask_priority)>

Sets the log mask for the current process to C<$mask_priority> and 
returns the old mask.  If the mask argument is 0, the current log mask 
is not modified.  See L<"Levels"> for the list of available levels. 
You can use the C<LOG_UPTO()> function to allow all levels up to a 
given priority (but it only accept the numeric macros as arguments).

B<Examples>

Only log errors: 

    setlogmask( LOG_MASK(LOG_ERR) );

Log everything except informational messages: 

    setlogmask( ~(LOG_MASK(LOG_INFO)) );

Log critical messages, errors and warnings: 

    setlogmask( LOG_MASK(LOG_CRIT) | LOG_MASK(LOG_ERR) | LOG_MASK(LOG_WARNING) );

Log all messages up to debug: 

    setlogmask( LOG_UPTO(LOG_DEBUG) );


=item B<setlogsock($sock_type)>

=item B<setlogsock($sock_type, $stream_location)> (added in Perl 5.004_02)

Sets the socket type to be used for the next call to
C<openlog()> or C<syslog()> and returns true on success,
C<undef> on failure. The available mechanisms are: 

=over

=item *

C<"native"> - use the native C functions from your C<syslog(3)> library
(added in C<Sys::Syslog> 0.15).

=item *

C<"eventlog"> - send messages to the Win32 events logger (Win32 only; 
added in C<Sys::Syslog> 0.19).

=item *

C<"tcp"> - connect to a TCP socket, on the C<syslog/tcp> or C<syslogng/tcp> 
service. 

=item *

C<"udp"> - connect to a UDP socket, on the C<syslog/udp> service.

=item *

C<"inet"> - connect to an INET socket, either TCP or UDP, tried in that order. 

=item *

C<"unix"> - connect to a UNIX domain socket (in some systems a character 
special device).  The name of that socket is the second parameter or, if 
you omit the second parameter, the value returned by the C<_PATH_LOG> macro 
(if your system defines it), or F</dev/log> or F</dev/conslog>, whatever is 
writable.  

=item *

C<"stream"> - connect to the stream indicated by the pathname provided as 
the optional second parameter, or, if omitted, to F</dev/conslog>. 
For example Solaris and IRIX system may prefer C<"stream"> instead of C<"unix">. 

=item *

C<"pipe"> - connect to the named pipe indicated by the pathname provided as 
the optional second parameter, or, if omitted, to the value returned by 
the C<_PATH_LOG> macro (if your system defines it), or F</dev/log>
(added in C<Sys::Syslog> 0.21).

=item *

C<"console"> - send messages directly to the console, as for the C<"cons"> 
option of C<openlog()>.