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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 | |
6 | require Exporter; |
7 | |
8 | @ISA = qw(Exporter); |
9 | @EXPORT = qw(ping pingecho); |
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10 | $VERSION = 1.00; |
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11 | |
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12 | use Socket 'PF_INET', 'AF_INET', 'SOCK_STREAM'; |
13 | require Carp ; |
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14 | |
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15 | use strict ; |
16 | |
17 | $Net::Ping::tcp_proto = (getprotobyname('tcp'))[2]; |
18 | $Net::Ping::echo_port = (getservbyname('echo', 'tcp'))[2]; |
19 | |
20 | # keep -w happy |
21 | $Net::Ping::tcp_proto = $Net::Ping::tcp_proto ; |
22 | $Net::Ping::echo_port = $Net::Ping::echo_port ; |
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23 | |
24 | sub ping { |
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25 | Carp::croak "ping not implemented yet. Use pingecho()"; |
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26 | } |
27 | |
28 | |
29 | sub pingecho { |
30 | |
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31 | Carp::croak "usage: pingecho host [timeout]" |
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32 | unless @_ == 1 || @_ == 2 ; |
33 | |
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34 | my ($host, $timeout) = @_; |
35 | my ($saddr, $ip); |
36 | my ($ret) ; |
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37 | local (*PINGSOCK); |
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38 | |
39 | # check if $host is alive by connecting to its echo port, within $timeout |
40 | # (default 5) seconds. returns 1 if OK, 0 if no answer, 0 if host not found |
41 | |
42 | $timeout = 5 unless $timeout; |
43 | |
44 | if ($host =~ /^\s*((\d+\.){3}\d+)\s*$/) |
45 | { $ip = pack ('C4', split (/\./, $1)) } |
46 | else |
47 | { $ip = (gethostbyname($host))[4] } |
48 | |
49 | return 0 unless $ip; # "no such host" |
50 | |
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51 | $saddr = pack('S n a4 x8', AF_INET, $Net::Ping::echo_port, $ip); |
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52 | $SIG{'ALRM'} = sub { die } ; |
53 | alarm($timeout); |
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54 | |
55 | $ret = 0; |
56 | eval <<'EOM' ; |
57 | return unless socket(PINGSOCK, PF_INET, SOCK_STREAM, $Net::Ping::tcp_proto) ; |
58 | return unless connect(PINGSOCK, $saddr) ; |
59 | $ret=1 ; |
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60 | EOM |
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61 | alarm(0); |
62 | close(PINGSOCK); |
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63 | $ret; |
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64 | } |
65 | |
66 | 1; |
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67 | __END__ |
68 | |
69 | =cut |
70 | |
71 | =head1 NAME |
72 | |
73 | Net::Ping, pingecho - check a host for upness |
74 | |
75 | =head1 SYNOPSIS |
76 | |
77 | use Net::Ping; |
78 | print "'jimmy' is alive and kicking\n" if pingecho('jimmy', 10) ; |
79 | |
80 | =head1 DESCRIPTION |
81 | |
82 | This module contains routines to test for the reachability of remote hosts. |
83 | Currently the only routine implemented is pingecho(). |
84 | |
85 | pingecho() uses a TCP echo (I<not> an ICMP one) to determine if the |
86 | remote host is reachable. This is usually adequate to tell that a remote |
87 | host is available to rsh(1), ftp(1), or telnet(1) onto. |
88 | |
89 | =head2 Parameters |
90 | |
91 | =over 5 |
92 | |
93 | =item hostname |
94 | |
95 | The remote host to check, specified either as a hostname or as an IP address. |
96 | |
97 | =item timeout |
98 | |
99 | The timeout in seconds. If not specified it will default to 5 seconds. |
100 | |
101 | =back |
102 | |
103 | =head1 WARNING |
104 | |
105 | pingecho() uses alarm to implement the timeout, so don't set another alarm |
106 | while you are using it. |
107 | |
108 | |