package Net::Ping;
-# Current maintainer: colinm@cpan.org (Colin McMillen)
-# stream protocol: bronson@trestle.com (Scott Bronson)
-#
-# Original author: mose@ccsn.edu (Russell Mosemann)
-#
-# Authors of the original pingecho():
-# karrer@bernina.ethz.ch (Andreas Karrer)
-# Paul.Marquess@btinternet.com (Paul Marquess)
-#
-# Copyright (c) 2001, Colin McMillen. All rights reserved. This
-# program is free software; you may redistribute it and/or modify it
-# under the same terms as Perl itself.
-use 5.006_001;
+# $Id: Ping.pm,v 1.11 2001/12/04 02:41:51 rob Exp $
+
+require 5.002;
require Exporter;
use strict;
-our(@ISA, @EXPORT, $VERSION, $def_timeout, $def_proto, $max_datasize);
+use vars qw(@ISA @EXPORT $VERSION
+ $def_timeout $def_proto $max_datasize $pingstring);
use FileHandle;
use Socket qw( SOCK_DGRAM SOCK_STREAM SOCK_RAW PF_INET
- inet_aton inet_ntoa sockaddr_in );
+ inet_aton sockaddr_in );
use Carp;
@ISA = qw(Exporter);
@EXPORT = qw(pingecho);
-$VERSION = 2.04;
+$VERSION = 2.07;
# Constants
$def_timeout = 5; # Default timeout to wait for a reply
$def_proto = "udp"; # Default protocol to use for pinging
$max_datasize = 1024; # Maximum data bytes in a packet
+# The data we exchange with the server for the stream protocol
+$pingstring = "pingschwingping!\n";
# Description: The pingecho() subroutine is provided for backward
# compatibility with the original Net::Ping. It accepts a host
# Description: Ping a host name or IP number with an optional timeout.
# First lookup the host, and return undef if it is not found. Otherwise
-# perform the specific ping method based on the protocol. Return the
+# perform the specific ping method based on the protocol. Return the
# result of the ping.
sub ping
$timeout # Seconds after which ping times out
) = @_;
- eval { require Net::Ping::External; };
- croak('Protocol "external" not supported on your system: Net::Ping::External not found') if $@;
+ eval { require Net::Ping::External; }
+ or croak('Protocol "external" not supported on your system: Net::Ping::External not found');
return Net::Ping::External::ping(ip => $ip, timeout => $timeout);
}
return(~(($chk >> 16) + $chk) & 0xffff); # Again and complement
}
-# Warning: this method may generate false positives.
-# It is meant to be a private method and should only
-# be invoked by ping_tcp() if $^O =~ /win32/i.
-sub _ping_tcp_win
+# Description: Perform a tcp echo ping. Since a tcp connection is
+# host specific, we have to open and close each connection here. We
+# can't just leave a socket open. Because of the robust nature of
+# tcp, it will take a while before it gives up trying to establish a
+# connection. Therefore, we use select() on a non-blocking socket to
+# check against our timeout. No data bytes are actually
+# sent since the successful establishment of a connection is proof
+# enough of the reachability of the remote host. Also, tcp is
+# expensive and doesn't need our help to add to the overhead.
+
+sub ping_tcp
{
my ($self,
$ip, # Packed IP number of the host
+ $timeout # Seconds after which ping times out
) = @_;
- my ($saddr, # sockaddr_in with port and ip
- $ret # The return value
+ my ($ret # The return value
);
- socket($self->{"fh"}, &PF_INET(), &SOCK_STREAM(), $self->{"proto_num"}) ||
- croak("tcp socket error - $!");
-
- $saddr = sockaddr_in($self->{"port_num"}, $ip);
-
- $ret = 0; # Default to unreachable
-
- eval { $ret = connect($self->{"fh"}, $saddr) };
-
- # If the remote host exists but returns "Connection refused",
- # the call to connect() sets $! to "Unknown error". So, we
- # assume that an "Unknown error" actually means the host is
- # alive. This assumption may occassionally give false positives.
- $ret = 1 if $! =~ /Unknown error/i;
-
+ $@ = "";
+ $ret = $self -> tcp_connect( $ip, $timeout);
+ $ret = 1 if $@ =~ /(Connection Refused|Unknown Error)/i;
$self->{"fh"}->close();
- return $ret;
+ return($ret);
}
-# Buggy Winsock API doesn't allow us to use non-blocking connect()
-# calls. Hence, if our OS is Windows, we need to create a new process
-# to run a blocking connect attempt, and kill it after the timeout has
-# passed. Unfortunately, this won't work with the stream protocol.
-
-sub ping_tcp_win32
+sub tcp_connect
{
my ($self,
$ip, # Packed IP number of the host
- $timeout # Seconds after which open times out
+ $timeout # Seconds after which connect times out
) = @_;
+ my ($saddr); # Packed IP and Port
- socket($self->{"fh"}, &PF_INET(), &SOCK_STREAM(), $self->{"proto_num"}) ||
- croak("tcp socket error - $!");
-
- my $saddr = sockaddr_in($self->{"port_num"}, $ip);
-
- my ($child, $ret, $pid, $time);
- my $host = inet_ntoa($ip);
-
- # The code we will be executing in our new process.
- my $code = '"use Net::Ping; $p = Net::Ping->new(\'tcp\'); ';
- $code .= 'exit($p->_ping_tcp_win(' . $host . '))"';
-
- # Call the process.
- $pid = system(1, "perl", "-e", $code);
-
- # Import the POSIX version of <sys/wait.h>
- require POSIX;
- import POSIX qw(:sys_wait_h);
-
- # Get the current time; will be used to tell if we've timed out.
- $time = time;
+ $saddr = sockaddr_in($self->{"port_num"}, $ip);
- # Wait for the child to return or for the timeout to expire.
- do {
- $child = waitpid($pid, &WNOHANG());
- $ret = $?;
- } until time > ($time + $timeout) or $child;
+ my $ret = 0; # Default to unreachable
- # Return an appropriate value; 0 if the child didn't return,
- # the return value of the child otherwise.
- return $ret >> 8 if $child;
+ my $do_socket = sub {
+ socket($self->{"fh"}, &PF_INET(), &SOCK_STREAM(), $self->{"proto_num"}) ||
+ croak("tcp socket error - $!");
+ };
+ my $do_connect = sub {
+ eval {
+ die $! unless connect($self->{"fh"}, $saddr);
+ $self->{"ip"} = $ip;
+ $ret = 1;
+ };
+ $ret;
+ };
+
+ if ($^O =~ /Win32/i) {
+
+ # Buggy Winsock API doesn't allow us to use alarm() calls.
+ # Hence, if our OS is Windows, we need to create a separate
+ # process to do the blocking connect attempt.
+
+ $| = 1; # Clear buffer prior to fork to prevent duplicate flushing.
+ my $pid = fork;
+ if (!$pid) {
+ if (!defined $pid) {
+ # Fork did not work
+ warn "Win32 Fork error: $!";
+ return 0;
+ }
+ &{ $do_socket }();
+
+ # Try a slow blocking connect() call
+ # and report the status to the pipe.
+ if ( &{ $do_connect }() ) {
+ $self->{"fh"}->close();
+ # No error
+ exit 0;
+ } else {
+ # Pass the error status to the parent
+ exit $!;
+ }
+ }
+
+ &{ $do_socket }();
+
+ my $patience = time + $timeout;
+
+ require POSIX;
+ my ($child);
+ $? = 0;
+ # Wait up to the timeout
+ # And clean off the zombie
+ do {
+ $child = waitpid($pid, &POSIX::WNOHANG);
+ $! = $? >> 8;
+ $@ = $!;
+ sleep 1;
+ } while time < $patience && $child != $pid;
+
+ if ($child == $pid) {
+ # Since she finished within the timeout,
+ # it is probably safe for me to try it too
+ &{ $do_connect }();
+ } else {
+ # Time must have run out.
+ $@ = "Timed out!";
+ # Put that choking client out of its misery
+ kill "KILL", $pid;
+ # Clean off the zombie
+ waitpid($pid, 0);
+ $ret = 0;
+ }
+ } else { # Win32
+ # Otherwise don't waste the resources to fork
+
+ &{ $do_socket }();
+
+ $SIG{'ALRM'} = sub { die "Timed out!"; };
+ alarm($timeout); # Interrupt connect() if we have to
+
+ &{ $do_connect }();
+ alarm(0);
+ }
- kill $pid;
- return 0;
+ return $ret;
}
# This writes the given string to the socket and then reads it
# back. It returns 1 on success, 0 on failure.
sub tcp_echo
{
- my $self = shift;
- my $timeout = shift;
- my $pingstring = shift;
+ my $self = shift;
+ my $timeout = shift;
+ my $pingstring = shift;
- my $ret = undef;
- my $time = time;
- my $wrstr = $pingstring;
- my $rdstr = "";
+ my $ret = undef;
+ my $time = time;
+ my $wrstr = $pingstring;
+ my $rdstr = "";
eval <<'EOM';
- do {
- my $rin = "";
- vec($rin, $self->{"fh"}->fileno(), 1) = 1;
-
- my $rout = undef;
- if($wrstr) {
- $rout = "";
- vec($rout, $self->{"fh"}->fileno(), 1) = 1;
- }
-
- if(select($rin, $rout, undef, ($time + $timeout) - time())) {
-
- if($rout && vec($rout,$self->{"fh"}->fileno(),1)) {
- my $num = syswrite($self->{"fh"}, $wrstr);
- if($num) {
- # If it was a partial write, update and try again.
- $wrstr = substr($wrstr,$num);
- } else {
- # There was an error.
- $ret = 0;
- }
- }
-
- if(vec($rin,$self->{"fh"}->fileno(),1)) {
- my $reply;
- if(sysread($self->{"fh"},$reply,length($pingstring)-length($rdstr))) {
- $rdstr .= $reply;
- $ret = 1 if $rdstr eq $pingstring;
- } else {
- # There was an error.
- $ret = 0;
- }
- }
-
- }
- } until time() > ($time + $timeout) || defined($ret);
+ do {
+ my $rin = "";
+ vec($rin, $self->{"fh"}->fileno(), 1) = 1;
+
+ my $rout = undef;
+ if($wrstr) {
+ $rout = "";
+ vec($rout, $self->{"fh"}->fileno(), 1) = 1;
+ }
+
+ if(select($rin, $rout, undef, ($time + $timeout) - time())) {
+
+ if($rout && vec($rout,$self->{"fh"}->fileno(),1)) {
+ my $num = syswrite($self->{"fh"}, $wrstr);
+ if($num) {
+ # If it was a partial write, update and try again.
+ $wrstr = substr($wrstr,$num);
+ } else {
+ # There was an error.
+ $ret = 0;
+ }
+ }
+
+ if(vec($rin,$self->{"fh"}->fileno(),1)) {
+ my $reply;
+ if(sysread($self->{"fh"},$reply,length($pingstring)-length($rdstr))) {
+ $rdstr .= $reply;
+ $ret = 1 if $rdstr eq $pingstring;
+ } else {
+ # There was an error.
+ $ret = 0;
+ }
+ }
+
+ }
+ } until time() > ($time + $timeout) || defined($ret);
EOM
- return $ret;
-}
-
-sub tcp_connect
-{
- my ($self,
- $ip, # Packed IP number of the host
- $timeout # Seconds after which open times out
- ) = @_;
-
- # Should we go back to using blocking IO and alarms to implement
- # the stream protocol on win32?
- croak "no nonblocking io -- can't stream ping on win32"
- if ($^O =~ /win32/i);
-
- $self->{"ip"} = $ip;
-
- socket($self->{"fh"}, &PF_INET(), &SOCK_STREAM(), $self->{"proto_num"}) ||
- croak("tcp socket error - $!");
-
- my $saddr = sockaddr_in($self->{"port_num"}, $ip);
- my $ret = 0;
-
- # Try a non-blocking TCP connect to the remote echo port.
- # Our call to select() below will stop after the timeout has
- # passed or set the return value to true if the connection
- # succeeds in time.
- $self->{"fh"}->blocking(0);
- connect($self->{"fh"}, $saddr);
-
- # This replaces the breakage where we were listening on a
- # socket that would never produce any data. This works, but
- # it's now quite a bit heavier than the old Net::Ping. I'd
- # like to see it reverted.
- return $self->tcp_echo($timeout, "ping!\n");
+ return $ret;
}
-# Description: Perform a tcp echo ping. Since a tcp connection is
-# host specific, we have to open and close each connection here. We
-# can't just leave a socket open. Because of the robust nature of
-# tcp, it will take a while before it gives up trying to establish a
-# connection. Therefore, we use select() on a non-blocking socket to
-# check against our timeout. No data bytes are actually
-# sent since the successful establishment of a connection is proof
-# enough of the reachability of the remote host. Also, tcp is
-# expensive and doesn't need our help to add to the overhead.
-
-sub ping_tcp
-{
- my ($self,
- $ip, # Packed IP number of the host
- $timeout # Seconds after which ping times out
- ) = @_;
- my $ret;
- # tcp_connect won't work on win32, so special-case it if need be.
- if ($^O =~ /win32/i) {
- $ret = $self->ping_tcp_win32($ip, $timeout);
- } else {
- $ret = $self->tcp_connect($ip, $timeout);
- $self->{"fh"}->close();
- }
-
- return $ret;
-}
# Description: Perform a stream ping. If the tcp connection isn't
# already open, it opens it. It then sends some data and waits for
$timeout # Seconds after which ping times out
) = @_;
- my $pingstring = "ping!\n"; # The data we exchange with the server
-
# Open the stream if it's not already open
if(!defined $self->{"fh"}->fileno()) {
$self->tcp_connect($ip, $timeout) or return 0;
croak "tried to switch servers while stream pinging"
if $self->{"ip"} ne $ip;
- return $self->tcp_echo($timeout, "pingschwingping!\n");
+ return $self->tcp_echo($timeout, $pingstring);
}
# Description: opens the stream. You would do this if you want to
sub open
{
- my ($self,
- $ip, # Packed IP number of the host
+ my ($self,
+ $host, # Host or IP address
$timeout # Seconds after which open times out
- ) = @_;
+ ) = @_;
- $timeout = $self->{"timeout"} unless $timeout;
+ my ($ip); # Packed IP number of the host
+ $ip = inet_aton($host);
+ $timeout = $self->{"timeout"} unless $timeout;
- if($self->{"proto"} eq "stream") {
- if(defined($self->{"fh"}->fileno())) {
- croak("socket is already open");
- } else {
- $self->tcp_connect($ip, $timeout);
- }
- }
+ if($self->{"proto"} eq "stream") {
+ if(defined($self->{"fh"}->fileno())) {
+ croak("socket is already open");
+ } else {
+ $self->tcp_connect($ip, $timeout);
+ }
+ }
}
+
# Description: Perform a udp echo ping. Construct a message of
# at least the one-byte sequence number and any additional data bytes.
# Send the message out and wait for a message to come back. If we
}
}
return($ret);
-}
+}
# Description: Close the connection unless we are using the tcp
# protocol, since it will already be closed.
Net::Ping - check a remote host for reachability
+$Id: Ping.pm,v 1.11 2001/12/04 02:41:51 rob Exp $
+
=head1 SYNOPSIS
use Net::Ping;
sleep(1);
}
$p->close();
-
+
$p = Net::Ping->new("tcp", 2);
+ # Try connecting to the www port instead of the echo port
+ $p->{port_num} = getservbyname("http", "tcp");
while ($stop_time > time())
{
print "$host not reachable ", scalar(localtime()), "\n"
sleep(300);
}
undef($p);
-
+
# For backward compatibility
print "$host is alive.\n" if pingecho($host);
parameters, a variable number of hosts may be pinged multiple
times and then the connection is closed.
-Ping supports five ping protocols, each with its own strengths
-and weaknesses. The "udp" protocol is the default. A host
-may be configured to respond to only a few of these protocols,
-or even none at all. For example, www.microsoft.com is generally
-alive but not pingable.
+You may choose one of four different protocols to use for the
+ping. The "udp" protocol is the default. Note that a live remote host
+may still fail to be pingable by one or more of these protocols. For
+example, www.microsoft.com is generally alive but not pingable.
-=over 4
-
-=item icmp
-
-The C<ping()> method sends an icmp echo message to the remote host
-(this is what the UNIX ping program does).
-If the echoed message is received from the remote host and
-the echoed information is correct, the remote host is considered
-reachable. Specifying this protocol requires that the program
-be run as root or that the program be setuid to root.
-
-=item udp
+With the "tcp" protocol the ping() method attempts to establish a
+connection to the remote host's echo port. If the connection is
+successfully established, the remote host is considered reachable. No
+data is actually echoed. This protocol does not require any special
+privileges but has higher overhead than the other two protocols.
-The C<ping()> method sends a udp
+Specifying the "udp" protocol causes the ping() method to send a udp
packet to the remote host's echo port. If the echoed packet is
received from the remote host and the received packet contains the
same data as the packet that was sent, the remote host is considered
reachable. This protocol does not require any special privileges.
-
-It should be borne in mind that, for both udp and tcp ping, a host
+It should be borne in mind that, for a udp ping, a host
will be reported as unreachable if it is not running the
-appropriate echo service. For Unix-like systems see L<inetd(8)> for
-more information.
+appropriate echo service. For Unix-like systems see L<inetd(8)>
+for more information.
-=item tcp
+If the "icmp" protocol is specified, the ping() method sends an icmp
+echo message to the remote host, which is what the UNIX ping program
+does. If the echoed message is received from the remote host and
+the echoed information is correct, the remote host is considered
+reachable. Specifying the "icmp" protocol requires that the program
+be run as root or that the program be setuid to root.
-The C<ping()> method attempts to establish a
-connection to the remote host's echo port. If the connection is
-successfully established, the remote host is considered reachable.
-Once the connection is made, it is torn down immediately -- no data
-is actually echoed. This protocol does not require any special
-privileges but has highest overhead of the protocols.
-
-=item stream
-
-This is just like the tcp protocol, except that once it establishes
-the tcp connection, it keeps it up. Each subsequent ping
-request re-uses the existing connection. stream
-provides better performance than tcp since the connection
-doesn't need to be created and torn down with every ping. It is
-also the only protocol that will recognize that the original host is
-gone, even if it is immediately replaced by an
-identical host responding in exactly the same way. The drawback
-is that you can only ping one host per Ping instance. You will get
-an error if you neglect to call C<close()> before trying to ping
-a different network device.
-
-=item external
-
-The ping() method attempts to use the C<Net::Ping::External> module to ping
-the remote host. C<Net::Ping::External> interfaces with your system's default
-L<ping(8)> utility to perform the ping, and generally produces relatively
+If the "external" protocol is specified, the ping() method attempts to
+use the C<Net::Ping::External> module to ping the remote host.
+C<Net::Ping::External> interfaces with your system's default C<ping>
+utility to perform the ping, and generally produces relatively
accurate results. If C<Net::Ping::External> if not installed on your
system, specifying the "external" protocol will result in an error.
provide a different timeout when creating the connection, or
remove the overhead of establishing the connection from the
first ping. If you don't call C<open()>, the connection is
-automatically openeed the first time C<ping()> is called.
+automatically opened the first time C<ping()> is called.
+This call simply does nothing if you are using any protocol other
+than stream.
+
+=item $p->open($host);
+
+When you are using the stream protocol, this call pre-opens the
+tcp socket. It's only necessary to do this if you want to
+provide a different timeout when creating the connection, or
+remove the overhead of establishing the connection from the
+first ping. If you don't call C<open()>, the connection is
+automatically opened the first time C<ping()> is called.
This call simply does nothing if you are using any protocol other
than stream.
=back
+=head1 WARNING
+
+pingecho() or a ping object with the tcp protocol use alarm() to
+implement the timeout. So, don't use alarm() in your program while
+you are using pingecho() or a ping object with the tcp protocol. The
+udp and icmp protocols do not use alarm() to implement the timeout.
+
=head1 NOTES
There will be less network overhead (and some efficiency in your
separate module to be written which understands all of the different
kinds of ICMP packets.
+=head1 AUTHOR(S)
+
+ Current maintainer Net::Ping base code:
+ colinm@cpan.org (Colin McMillen)
+
+ Stream protocol:
+ bronson@trestle.com (Scott Bronson)
+
+ Original pingecho():
+ karrer@bernina.ethz.ch (Andreas Karrer)
+ pmarquess@bfsec.bt.co.uk (Paul Marquess)
+
+ Original Net::Ping author:
+ mose@ns.ccsn.edu (Russell Mosemann)
+
+ Compatibility porting:
+ bbb@cpan.org (Rob Brown)
+
+=head1 COPYRIGHT
+
+Copyright (c) 2001, Colin McMillen. All rights reserved.
+Copyright (c) 2001, Rob Brown. All rights reserved.
+
+This program is free software; you may redistribute it and/or
+modify it under the same terms as Perl itself.
+
=cut
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