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1 | package Net::Ping; |
2 | |
3 | # Authors: karrer@bernina.ethz.ch (Andreas Karrer) |
4 | # pmarquess@bfsec.bt.co.uk (Paul Marquess) |
5 | |
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6 | require 5.002 ; |
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7 | require Exporter; |
8 | |
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9 | use strict ; |
10 | use vars qw(@ISA @EXPORT $VERSION $tcp_proto $echo_port) ; |
11 | |
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12 | @ISA = qw(Exporter); |
13 | @EXPORT = qw(ping pingecho); |
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14 | $VERSION = 1.01; |
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15 | |
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16 | use Socket 'PF_INET', 'AF_INET', 'SOCK_STREAM'; |
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17 | use Carp ; |
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18 | |
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19 | $tcp_proto = (getprotobyname('tcp'))[2]; |
20 | $echo_port = (getservbyname('echo', 'tcp'))[2]; |
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21 | |
22 | sub ping { |
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23 | croak "ping not implemented yet. Use pingecho()"; |
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24 | } |
25 | |
26 | |
27 | sub pingecho { |
28 | |
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29 | croak "usage: pingecho host [timeout]" |
30 | unless @_ == 1 or @_ == 2 ; |
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31 | |
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32 | my ($host, $timeout) = @_; |
33 | my ($saddr, $ip); |
34 | my ($ret) ; |
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35 | local (*PINGSOCK); |
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36 | |
37 | # check if $host is alive by connecting to its echo port, within $timeout |
38 | # (default 5) seconds. returns 1 if OK, 0 if no answer, 0 if host not found |
39 | |
40 | $timeout = 5 unless $timeout; |
41 | |
42 | if ($host =~ /^\s*((\d+\.){3}\d+)\s*$/) |
43 | { $ip = pack ('C4', split (/\./, $1)) } |
44 | else |
45 | { $ip = (gethostbyname($host))[4] } |
46 | |
47 | return 0 unless $ip; # "no such host" |
48 | |
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49 | $saddr = pack('S n a4 x8', AF_INET, $echo_port, $ip); |
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50 | $SIG{'ALRM'} = sub { die } ; |
51 | alarm($timeout); |
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52 | |
53 | $ret = 0; |
54 | eval <<'EOM' ; |
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55 | return unless socket(PINGSOCK, PF_INET, SOCK_STREAM, $tcp_proto) ; |
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56 | return unless connect(PINGSOCK, $saddr) ; |
57 | $ret=1 ; |
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58 | EOM |
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59 | alarm(0); |
60 | close(PINGSOCK); |
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61 | $ret; |
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62 | } |
63 | |
64 | 1; |
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65 | __END__ |
66 | |
67 | =cut |
68 | |
69 | =head1 NAME |
70 | |
71 | Net::Ping, pingecho - check a host for upness |
72 | |
73 | =head1 SYNOPSIS |
74 | |
75 | use Net::Ping; |
76 | print "'jimmy' is alive and kicking\n" if pingecho('jimmy', 10) ; |
77 | |
78 | =head1 DESCRIPTION |
79 | |
80 | This module contains routines to test for the reachability of remote hosts. |
81 | Currently the only routine implemented is pingecho(). |
82 | |
83 | pingecho() uses a TCP echo (I<not> an ICMP one) to determine if the |
84 | remote host is reachable. This is usually adequate to tell that a remote |
85 | host is available to rsh(1), ftp(1), or telnet(1) onto. |
86 | |
87 | =head2 Parameters |
88 | |
89 | =over 5 |
90 | |
91 | =item hostname |
92 | |
93 | The remote host to check, specified either as a hostname or as an IP address. |
94 | |
95 | =item timeout |
96 | |
97 | The timeout in seconds. If not specified it will default to 5 seconds. |
98 | |
99 | =back |
100 | |
101 | =head1 WARNING |
102 | |
103 | pingecho() uses alarm to implement the timeout, so don't set another alarm |
104 | while you are using it. |
105 | |
106 | |