package Net::Ping;
-# Authors: karrer@bernina.ethz.ch (Andreas Karrer)
-# pmarquess@bfsec.bt.co.uk (Paul Marquess)
-
-require 5.002 ;
+# Author: mose@ccsn.edu (Russell Mosemann)
+#
+# Authors of the original pingecho():
+# karrer@bernina.ethz.ch (Andreas Karrer)
+# pmarquess@bfsec.bt.co.uk (Paul Marquess)
+#
+# Copyright (c) 1996 Russell Mosemann. All rights reserved. This
+# program is free software; you may redistribute it and/or modify it
+# under the same terms as Perl itself.
+
+require 5.002;
require Exporter;
-use strict ;
-use vars qw(@ISA @EXPORT $VERSION $tcp_proto $echo_port) ;
+use strict;
+use vars qw(@ISA @EXPORT $VERSION
+ $def_timeout $def_proto $max_datasize);
+use FileHandle;
+use Socket qw( SOCK_DGRAM SOCK_STREAM SOCK_RAW PF_INET
+ inet_aton sockaddr_in );
+use Carp;
@ISA = qw(Exporter);
-@EXPORT = qw(ping pingecho);
-$VERSION = 1.01;
-
-use Socket 'PF_INET', 'AF_INET', 'SOCK_STREAM';
-use Carp ;
-
-$tcp_proto = (getprotobyname('tcp'))[2];
-$echo_port = (getservbyname('echo', 'tcp'))[2];
-
-sub ping {
- croak "ping not implemented yet. Use pingecho()";
-}
+@EXPORT = qw(pingecho);
+$VERSION = 2.02;
+# Constants
-sub pingecho {
+$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
- croak "usage: pingecho host [timeout]"
- unless @_ == 1 or @_ == 2 ;
+# Description: The pingecho() subroutine is provided for backward
+# compatibility with the original Net::Ping. It accepts a host
+# name/IP and an optional timeout in seconds. Create a tcp ping
+# object and try pinging the host. The result of the ping is returned.
- my ($host, $timeout) = @_;
- my ($saddr, $ip);
- my ($ret) ;
- local (*PINGSOCK);
+sub pingecho
+{
+ my ($host, # Name or IP number of host to ping
+ $timeout # Optional timeout in seconds
+ ) = @_;
+ my ($p); # A ping object
- # check if $host is alive by connecting to its echo port, within $timeout
- # (default 5) seconds. returns 1 if OK, 0 if no answer, 0 if host not found
+ $p = Net::Ping->new("tcp", $timeout);
+ $p->ping($host); # Going out of scope closes the connection
+}
- $timeout = 5 unless $timeout;
+# Description: The new() method creates a new ping object. Optional
+# parameters may be specified for the protocol to use, the timeout in
+# seconds and the size in bytes of additional data which should be
+# included in the packet.
+# After the optional parameters are checked, the data is constructed
+# and a socket is opened if appropriate. The object is returned.
+
+sub new
+{
+ my ($this,
+ $proto, # Optional protocol to use for pinging
+ $timeout, # Optional timeout in seconds
+ $data_size # Optional additional bytes of data
+ ) = @_;
+ my $class = ref($this) || $this;
+ my $self = {};
+ my ($cnt, # Count through data bytes
+ $min_datasize # Minimum data bytes required
+ );
+
+ bless($self, $class);
+
+ $proto = $def_proto unless $proto; # Determine the protocol
+ croak("Protocol for ping must be \"tcp\", \"udp\" or \"icmp\"")
+ unless $proto =~ m/^(tcp|udp|icmp)$/;
+ $self->{"proto"} = $proto;
+
+ $timeout = $def_timeout unless $timeout; # Determine the timeout
+ croak("Default timeout for ping must be greater than 0 seconds")
+ if $timeout <= 0;
+ $self->{"timeout"} = $timeout;
+
+ $min_datasize = ($proto eq "udp") ? 1 : 0; # Determine data size
+ $data_size = $min_datasize unless defined($data_size) && $proto ne "tcp";
+ croak("Data for ping must be from $min_datasize to $max_datasize bytes")
+ if ($data_size < $min_datasize) || ($data_size > $max_datasize);
+ $data_size-- if $self->{"proto"} eq "udp"; # We provide the first byte
+ $self->{"data_size"} = $data_size;
+
+ $self->{"data"} = ""; # Construct data bytes
+ for ($cnt = 0; $cnt < $self->{"data_size"}; $cnt++)
+ {
+ $self->{"data"} .= chr($cnt % 256);
+ }
+
+ $self->{"seq"} = 0; # For counting packets
+ if ($self->{"proto"} eq "udp") # Open a socket
+ {
+ $self->{"proto_num"} = (getprotobyname('udp'))[2] ||
+ croak("Can't udp protocol by name");
+ $self->{"port_num"} = (getservbyname('echo', 'udp'))[2] ||
+ croak("Can't get udp echo port by name");
+ $self->{"fh"} = FileHandle->new();
+ socket($self->{"fh"}, &PF_INET(), &SOCK_DGRAM(),
+ $self->{"proto_num"}) ||
+ croak("udp socket error - $!");
+ }
+ elsif ($self->{"proto"} eq "icmp")
+ {
+ croak("icmp ping requires root privilege") if $>;
+ $self->{"proto_num"} = (getprotobyname('icmp'))[2] ||
+ croak("Can't get icmp protocol by name");
+ $self->{"pid"} = $$ & 0xffff; # Save lower 16 bits of pid
+ $self->{"fh"} = FileHandle->new();
+ socket($self->{"fh"}, &PF_INET(), &SOCK_RAW(), $self->{"proto_num"}) ||
+ croak("icmp socket error - $!");
+ }
+ elsif ($self->{"proto"} eq "tcp") # Just a file handle for now
+ {
+ $self->{"proto_num"} = (getprotobyname('tcp'))[2] ||
+ croak("Can't get tcp protocol by name");
+ $self->{"port_num"} = (getservbyname('echo', 'tcp'))[2] ||
+ croak("Can't get tcp echo port by name");
+ $self->{"fh"} = FileHandle->new();
+ }
+
+
+ return($self);
+}
- if ($host =~ /^\s*((\d+\.){3}\d+)\s*$/)
- { $ip = pack ('C4', split (/\./, $1)) }
+# Description: Ping a host name or IP number with an optional timeout.
+# First lookup the host, and return undef if it is not found. Otherwise
+# perform the specific ping method based on the protocol. Return the
+# result of the ping.
+
+sub ping
+{
+ my ($self,
+ $host, # Name or IP number of host to ping
+ $timeout # Seconds after which ping times out
+ ) = @_;
+ my ($ip, # Packed IP number of $host
+ $ret # The return value
+ );
+
+ croak("Usage: \$p->ping(\$host [, \$timeout])") unless @_ == 2 || @_ == 3;
+ $timeout = $self->{"timeout"} unless $timeout;
+ croak("Timeout must be greater than 0 seconds") if $timeout <= 0;
+
+ $ip = inet_aton($host);
+ return(undef) unless defined($ip); # Does host exist?
+
+ if ($self->{"proto"} eq "udp")
+ {
+ $ret = $self->ping_udp($ip, $timeout);
+ }
+ elsif ($self->{"proto"} eq "icmp")
+ {
+ $ret = $self->ping_icmp($ip, $timeout);
+ }
+ elsif ($self->{"proto"} eq "tcp")
+ {
+ $ret = $self->ping_tcp($ip, $timeout);
+ }
else
- { $ip = (gethostbyname($host))[4] }
-
- return 0 unless $ip; # "no such host"
+ {
+ croak("Unknown protocol \"$self->{proto}\" in ping()");
+ }
+ return($ret);
+}
- $saddr = pack('S n a4 x8', AF_INET, $echo_port, $ip);
- $SIG{'ALRM'} = sub { die } ;
- alarm($timeout);
-
+sub ping_icmp
+{
+ my ($self,
+ $ip, # Packed IP number of the host
+ $timeout # Seconds after which ping times out
+ ) = @_;
+
+ my $ICMP_ECHOREPLY = 0; # ICMP packet types
+ my $ICMP_ECHO = 8;
+ my $icmp_struct = "C2 S3 A"; # Structure of a minimal ICMP packet
+ my $subcode = 0; # No ICMP subcode for ECHO and ECHOREPLY
+ my $flags = 0; # No special flags when opening a socket
+ my $port = 0; # No port with ICMP
+
+ my ($saddr, # sockaddr_in with port and ip
+ $checksum, # Checksum of ICMP packet
+ $msg, # ICMP packet to send
+ $len_msg, # Length of $msg
+ $rbits, # Read bits, filehandles for reading
+ $nfound, # Number of ready filehandles found
+ $finish_time, # Time ping should be finished
+ $done, # set to 1 when we are done
+ $ret, # Return value
+ $recv_msg, # Received message including IP header
+ $from_saddr, # sockaddr_in of sender
+ $from_port, # Port packet was sent from
+ $from_ip, # Packed IP of sender
+ $from_type, # ICMP type
+ $from_subcode, # ICMP subcode
+ $from_chk, # ICMP packet checksum
+ $from_pid, # ICMP packet id
+ $from_seq, # ICMP packet sequence
+ $from_msg # ICMP message
+ );
+
+ $self->{"seq"} = ($self->{"seq"} + 1) % 65536; # Increment sequence
+ $checksum = 0; # No checksum for starters
+ $msg = pack($icmp_struct . $self->{"data_size"}, $ICMP_ECHO, $subcode,
+ $checksum, $self->{"pid"}, $self->{"seq"}, $self->{"data"});
+ $checksum = Net::Ping->checksum($msg);
+ $msg = pack($icmp_struct . $self->{"data_size"}, $ICMP_ECHO, $subcode,
+ $checksum, $self->{"pid"}, $self->{"seq"}, $self->{"data"});
+ $len_msg = length($msg);
+ $saddr = sockaddr_in($port, $ip);
+ send($self->{"fh"}, $msg, $flags, $saddr); # Send the message
+
+ $rbits = "";
+ vec($rbits, $self->{"fh"}->fileno(), 1) = 1;
$ret = 0;
+ $done = 0;
+ $finish_time = time() + $timeout; # Must be done by this time
+ while (!$done && $timeout > 0) # Keep trying if we have time
+ {
+ $nfound = select($rbits, undef, undef, $timeout); # Wait for packet
+ $timeout = $finish_time - time(); # Get remaining time
+ if (!defined($nfound)) # Hmm, a strange error
+ {
+ $ret = undef;
+ $done = 1;
+ }
+ elsif ($nfound) # Got a packet from somewhere
+ {
+ $recv_msg = "";
+ $from_saddr = recv($self->{"fh"}, $recv_msg, 1500, $flags);
+ ($from_port, $from_ip) = sockaddr_in($from_saddr);
+ ($from_type, $from_subcode, $from_chk,
+ $from_pid, $from_seq, $from_msg) =
+ unpack($icmp_struct . $self->{"data_size"},
+ substr($recv_msg, length($recv_msg) - $len_msg,
+ $len_msg));
+ if (($from_type == $ICMP_ECHOREPLY) &&
+ ($from_ip eq $ip) &&
+ ($from_pid == $self->{"pid"}) && # Does the packet check out?
+ ($from_seq == $self->{"seq"}))
+ {
+ $ret = 1; # It's a winner
+ $done = 1;
+ }
+ }
+ else # Oops, timed out
+ {
+ $done = 1;
+ }
+ }
+ return($ret)
+}
+
+# Description: Do a checksum on the message. Basically sum all of
+# the short words and fold the high order bits into the low order bits.
+
+sub checksum
+{
+ my ($class,
+ $msg # The message to checksum
+ ) = @_;
+ my ($len_msg, # Length of the message
+ $num_short, # The number of short words in the message
+ $short, # One short word
+ $chk # The checksum
+ );
+
+ $len_msg = length($msg);
+ $num_short = $len_msg / 2;
+ $chk = 0;
+ foreach $short (unpack("S$num_short", $msg))
+ {
+ $chk += $short;
+ } # Add the odd byte in
+ $chk += unpack("C", substr($msg, $len_msg - 1, 1)) if $len_msg % 2;
+ $chk = ($chk >> 16) + ($chk & 0xffff); # Fold high into low
+ return(~(($chk >> 16) + $chk) & 0xffff); # Again and complement
+}
+
+# Description: Perform a tcp echo ping. Since a tcp connection is
+# host specific, we have to open and close each connection here. We
+# can't just leave a socket open. Because of the robust nature of
+# tcp, it will take a while before it gives up trying to establish a
+# connection. Therefore, we have to set the alarm to break out of the
+# connection sooner if the timeout expires. No data bytes are actually
+# sent since the successful establishment of a connection is proof
+# enough of the reachability of the remote host. Also, tcp is
+# expensive and doesn't need our help to add to the overhead.
+
+sub ping_tcp
+{
+ my ($self,
+ $ip, # Packed IP number of the host
+ $timeout # Seconds after which ping times out
+ ) = @_;
+ my ($saddr, # sockaddr_in with port and ip
+ $ret # The return value
+ );
+
+ socket($self->{"fh"}, &PF_INET(), &SOCK_STREAM(), $self->{"proto_num"}) ||
+ croak("tcp socket error - $!");
+ $saddr = sockaddr_in($self->{"port_num"}, $ip);
+
+ $SIG{'ALRM'} = sub { die };
+ alarm($timeout); # Interrupt connect() if we have to
+
+ $ret = 0; # Default to unreachable
eval <<'EOM' ;
- return unless socket(PINGSOCK, PF_INET, SOCK_STREAM, $tcp_proto) ;
- return unless connect(PINGSOCK, $saddr) ;
- $ret=1 ;
+ return unless connect($self->{"fh"}, $saddr);
+ $ret = 1;
EOM
alarm(0);
- close(PINGSOCK);
- $ret;
+ $self->{"fh"}->close();
+ return($ret);
+}
+
+# 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
+# get a message, make sure all of its parts match. If they do, we are
+# done. Otherwise go back and wait for the message until we run out
+# of time. Return the result of our efforts.
+
+sub ping_udp
+{
+ my ($self,
+ $ip, # Packed IP number of the host
+ $timeout # Seconds after which ping times out
+ ) = @_;
+
+ my $flags = 0; # Nothing special on open
+
+ my ($saddr, # sockaddr_in with port and ip
+ $ret, # The return value
+ $msg, # Message to be echoed
+ $finish_time, # Time ping should be finished
+ $done, # Set to 1 when we are done pinging
+ $rbits, # Read bits, filehandles for reading
+ $nfound, # Number of ready filehandles found
+ $from_saddr, # sockaddr_in of sender
+ $from_msg, # Characters echoed by $host
+ $from_port, # Port message was echoed from
+ $from_ip # Packed IP number of sender
+ );
+
+ $saddr = sockaddr_in($self->{"port_num"}, $ip);
+ $self->{"seq"} = ($self->{"seq"} + 1) % 256; # Increment sequence
+ $msg = chr($self->{"seq"}) . $self->{"data"}; # Add data if any
+ send($self->{"fh"}, $msg, $flags, $saddr); # Send it
+
+ $rbits = "";
+ vec($rbits, $self->{"fh"}->fileno(), 1) = 1;
+ $ret = 0; # Default to unreachable
+ $done = 0;
+ $finish_time = time() + $timeout; # Ping needs to be done by then
+ while (!$done && $timeout > 0)
+ {
+ $nfound = select($rbits, undef, undef, $timeout); # Wait for response
+ $timeout = $finish_time - time(); # Get remaining time
+
+ if (!defined($nfound)) # Hmm, a strange error
+ {
+ $ret = undef;
+ $done = 1;
+ }
+ elsif ($nfound) # A packet is waiting
+ {
+ $from_msg = "";
+ $from_saddr = recv($self->{"fh"}, $from_msg, 1500, $flags);
+ ($from_port, $from_ip) = sockaddr_in($from_saddr);
+ if (($from_ip eq $ip) && # Does the packet check out?
+ ($from_port == $self->{"port_num"}) &&
+ ($from_msg eq $msg))
+ {
+ $ret = 1; # It's a winner
+ $done = 1;
+ }
+ }
+ else # Oops, timed out
+ {
+ $done = 1;
+ }
+ }
+ return($ret);
}
+# Description: Close the connection unless we are using the tcp
+# protocol, since it will already be closed.
+
+sub close
+{
+ my ($self) = @_;
+
+ $self->{"fh"}->close() unless $self->{"proto"} eq "tcp";
+}
+
+
1;
__END__
-=cut
-
=head1 NAME
-Net::Ping, pingecho - check a host for upness
+Net::Ping - check a remote host for reachability
=head1 SYNOPSIS
use Net::Ping;
- print "'jimmy' is alive and kicking\n" if pingecho('jimmy', 10) ;
-
-=head1 DESCRIPTION
-This module contains routines to test for the reachability of remote hosts.
-Currently the only routine implemented is pingecho().
+ $p = Net::Ping->new();
+ print "$host is alive.\n" if $p->ping($host);
+ $p->close();
+
+ $p = Net::Ping->new("icmp");
+ foreach $host (@host_array)
+ {
+ print "$host is ";
+ print "NOT " unless $p->ping($host, 2);
+ print "reachable.\n";
+ sleep(1);
+ }
+ $p->close();
+
+ $p = Net::Ping->new("tcp", 2);
+ while ($stop_time > time())
+ {
+ print "$host not reachable ", scalar(localtime()), "\n"
+ unless $p->ping($host);
+ sleep(300);
+ }
+ undef($p);
+
+ # For backward compatibility
+ print "$host is alive.\n" if pingecho($host);
-pingecho() uses a TCP echo (I<not> an ICMP one) to determine if the
-remote host is reachable. This is usually adequate to tell that a remote
-host is available to rsh(1), ftp(1), or telnet(1) onto.
+=head1 DESCRIPTION
-=head2 Parameters
+This module contains methods to test the reachability of remote
+hosts on a network. A ping object is first created with optional
+parameters, a variable number of hosts may be pinged multiple
+times and then the connection is closed.
+
+You may choose one of three different protocols to use for the ping.
+With the "tcp" protocol the ping() method attempts to establish a
+connection to the remote host's echo port. If the connection is
+successfully established, the remote host is considered reachable. No
+data is actually echoed. This protocol does not require any special
+privileges but has higher overhead than the other two protocols.
+
+Specifying the "udp" protocol causes the ping() method to send a udp
+packet to the remote host's echo port. If the echoed packet is
+received from the remote host and the received packet contains the
+same data as the packet that was sent, the remote host is considered
+reachable. This protocol does not require any special privileges.
+
+If the "icmp" protocol is specified, the ping() method sends an icmp
+echo message to the remote host, which is what the UNIX ping program
+does. If the echoed message is received from the remote host and
+the echoed information is correct, the remote host is considered
+reachable. Specifying the "icmp" protocol requires that the program
+be run as root or that the program be setuid to root.
+
+=head2 Functions
+
+=over 4
+
+=item Net::Ping->new([$proto [, $def_timeout [, $bytes]]]);
+
+Create a new ping object. All of the parameters are optional. $proto
+specifies the protocol to use when doing a ping. The current choices
+are "tcp", "udp" or "icmp". The default is "udp".
+
+If a default timeout ($def_timeout) in seconds is provided, it is used
+when a timeout is not given to the ping() method (below). The timeout
+must be greater than 0 and the default, if not specified, is 5 seconds.
+
+If the number of data bytes ($bytes) is given, that many data bytes
+are included in the ping packet sent to the remote host. The number of
+data bytes is ignored if the protocol is "tcp". The minimum (and
+default) number of data bytes is 1 if the protocol is "udp" and 0
+otherwise. The maximum number of data bytes that can be specified is
+1024.
+
+=item $p->ping($host [, $timeout]);
+
+Ping the remote host and wait for a response. $host can be either the
+hostname or the IP number of the remote host. The optional timeout
+must be greater than 0 seconds and defaults to whatever was specified
+when the ping object was created. If the hostname cannot be found or
+there is a problem with the IP number, undef is returned. Otherwise,
+1 is returned if the host is reachable and 0 if it is not. For all
+practical purposes, undef and 0 and can be treated as the same case.
+
+=item $p->close();
+
+Close the network connection for this ping object. The network
+connection is also closed by "undef $p". The network connection is
+automatically closed if the ping object goes out of scope (e.g. $p is
+local to a subroutine and you leave the subroutine).
+
+=item pingecho($host [, $timeout]);
+
+To provide backward compatibility with the previous version of
+Net::Ping, a pingecho() subroutine is available with the same
+functionality as before. pingecho() uses the tcp protocol. The
+return values and parameters are the same as described for the ping()
+method. This subroutine is obsolete and may be removed in a future
+version of Net::Ping.
-=over 5
+=back
-=item hostname
+=head1 WARNING
-The remote host to check, specified either as a hostname or as an IP address.
+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.
-=item timeout
+=head1 NOTES
-The timeout in seconds. If not specified it will default to 5 seconds.
+There will be less network overhead (and some efficiency in your
+program) if you specify either the udp or the icmp protocol. The tcp
+protocol will generate 2.5 times or more traffic for each ping than
+either udp or icmp. If many hosts are pinged frequently, you may wish
+to implement a small wait (e.g. 25ms or more) between each ping to
+avoid flooding your network with packets.
-=back
+The icmp protocol requires that the program be run as root or that it
+be setuid to root. The tcp and udp protocols do not require special
+privileges, but not all network devices implement the echo protocol
+for tcp or udp.
-=head1 WARNING
+Local hosts should normally respond to pings within milliseconds.
+However, on a very congested network it may take up to 3 seconds or
+longer to receive an echo packet from the remote host. If the timeout
+is set too low under these conditions, it will appear that the remote
+host is not reachable (which is almost the truth).
-pingecho() uses alarm to implement the timeout, so don't set another alarm
-while you are using it.
+Reachability doesn't necessarily mean that the remote host is actually
+functioning beyond its ability to echo packets.
+Because of a lack of anything better, this module uses its own
+routines to pack and unpack ICMP packets. It would be better for a
+separate module to be written which understands all of the different
+kinds of ICMP packets.
+=cut
projects / p5sagit/p5-mst-13.2.git / commitdiff