diff options
Diffstat (limited to 'contrib/perl5/lib/Net/Ping.pm')
| -rw-r--r-- | contrib/perl5/lib/Net/Ping.pm | 36 |
1 files changed, 23 insertions, 13 deletions
diff --git a/contrib/perl5/lib/Net/Ping.pm b/contrib/perl5/lib/Net/Ping.pm index 2713383..a2846fe 100644 --- a/contrib/perl5/lib/Net/Ping.pm +++ b/contrib/perl5/lib/Net/Ping.pm @@ -269,13 +269,13 @@ sub checksum ); $len_msg = length($msg); - $num_short = $len_msg / 2; + $num_short = int($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; + $chk += (unpack("C", substr($msg, $len_msg - 1, 1)) << 8) if $len_msg % 2; $chk = ($chk >> 16) + ($chk & 0xffff); # Fold high into low return(~(($chk >> 16) + $chk) & 0xffff); # Again and complement } @@ -369,16 +369,17 @@ sub ping_udp elsif ($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; - } - } + $from_saddr = recv($self->{"fh"}, $from_msg, 1500, $flags) + or last; # For example an unreachable host will make recv() fail. + ($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; @@ -442,7 +443,11 @@ 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. +You may choose one of three 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. + 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 @@ -455,6 +460,11 @@ 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 tcp and 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. + 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 |
