Perl regular expression to match an IP address

问题:

I have written this code, but it does not work. Can someone point out the issue?

sub match_ip()
{
  my $ip = "The IP address is 216.108.225.236:60099";
  if($ip =~ /(\d{1-3}\.\d{1-3}\.\d{1-3}\.\d{1-3}\:\d{1-5})/)
  {
      print "$1\n";
  }
}

EDIT: I wanted to just extract the IP address, not do any validation.

回答1:

Change {1-3} to {1,3} same for {1-5} -> {1,5}

回答2:

In the spirit of TIMTOWTDI here is another: the Regexp::Common::net portion of Regexp::Common may have regexen that you desire.

回答3:

Alternatively, you can use Data::Validate::IP, with the caveat that it won't recognize the port, so you'll have to split on :.

use strict;
use warnings;
use Data::Validate::IP;

my $ip_with_port="216.108.225.236:60099";
my $ip=(split /:/,$ip_with_port)[0];

my $validator=Data::Validate::IP->new;

if($validator->is_ipv4($ip))
{
  print "Yep, $ip is a valid IPv4 address.\n";
}
else
{
  print "Nope, $ip is not a valid IPv4 address.\n";
}

The output is:

Yep, 216.108.225.236 is a valid IPv4 address.

回答4:

Replace the dashes with commas.

/(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\:\d{1,5})/

回答5:

Though there are well documented and tested modules at CPAN to match and validate IP addresses but there must be some solid reason for you not to use it. Personally I never had a real reason to use them for validation purpose either since I trusted/feeded the input.

Here is a shorter version of your regex, with it's own pitfalls:

while (my $ip = <DATA>)  {
    chomp $ip;
    # older version
    # if($ip =~ /(\d{1-3}\.\d{1-3}\.\d{1-3}\.\d{1-3}\:\d{1-5})/)

    # see below for explanation
    if ($ip =~ /\b(\d{1,3}(?:\.\d{1,3}){3}:\d{1,5})\b/)
    {
        print "$ip - matches\n";
    } else {
        print "$ip - does not match\n";
    }
}

__DATA__
216.108.225.236:60099
4.2.2.1:1
216.108.225.236:0
1216.1108.1225.1236:1234
216.108.225.236x:123
9216.108.225.236:8472
10.10.10.10

Results:

216.108.225.236:60099 - matches
4.2.2.1:1 - matches
216.108.225.236:0 - matches
1216.1108.1225.1236:1234 - does not match
216.108.225.236x:123 - does not match
9216.108.225.236:8472 - does not match
10.10.10.10 - does not match

Explanation:

/\b             # word boundary
(               # start memory capture group 1
\d{1,3}         # one to three digits, first octat
(:?             # start non memory capture group, notice ?:
  \.\d{1,3}     # a literal dot followed by an ip octet
)               # end non memory capture group
{3}             # three times of dots and ip octets
:               # match a colon
\d{1,5}         # port number, one to five digits
)               # end of memory capture group 1
\b              # word boundary

Hope this helps.

回答6:

This might help:

my $ip = "195.249.61.14";

my @ips = (
    "set protocols bgp group IBGP-RRCL-CUSTOMER neighbor 195.249.61.142",
    "set protocols bgp group IBGP-RRCL-CUSTOMER neighbor 195.249.61.14",
    "set protocols bgp group IBGP-RRCL-CUSTOMER neighbor 195.249.61.141"
);

foreach (@ips) {
   print "$_\n" if ( /\b$ip\b/ );
}

Output:

set protocols bgp group IBGP-RRCL-CUSTOMER neighbor 195.249.61.14

回答7:

http://metacpan.org/pod/Regexp::Common::net

If you extract an IP address that is not an IP address... you are not extracting the right thing.

回答8:

#!/usr/bin/perl

$str = 'IP address is : 70.21.311.105';

    if ($str =~ m/(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})/) {
        if ($1 <= 255 && $2 <= 255 && $3 <= 255 && $4 <= 255 ) {
            print "Valid $str\n";
    } else {
          print "invalid IP $str\n";
    }
}


__END__

回答9:

Try this:

$variablename=~m/((((0-9)|((1-9)(0-9))|(1([0-9]){2})|(2[0-4][0-9])|(2[5][0-5]))\.){3})((0-9)|((1-9)(0-9))|(1([0-9]){2})|(2[0-4][0-9])|(25[0-5]))/)

回答10:

use strict;
use warnings;
open(FH,"<fileName.txt") or die "file not found ,$_";
while(my $line=<FH>)
{
push(my @arr,($line));
foreach my $arrVal (@arr)
{           
if($arrVal=~/IPv4 Address(?=.*\b((25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2  [0-4]\d|[0-1]?\d?\d)){3})\b)/)
{
print "$arrVal\n";
}
}

回答11:

You can also use the following regex to make sure that the quad's aren't bigger then 255, it also "reuses" the digit matching instead of copypasting it 4 times.

my $rx = qr/^(?!(\.))(\.?(\d{1,3})(?(?{$^N > 255})(*FAIL))){4}$/;
if('192.168.1.2' =~ $rx){
  print "OK\n";
}

It uses a few features from perl regex matching (man perlre):

• (*FAIL): stops pattern matching and fails
• (?(condition)...): conditional match
• (?{ code }): used within that condition

回答12:

$ip = "10.255.256.1";

# will accept valid ips
if ($ip =~ m/^([1|2][0-9]{1,2})\.([0-255]{1,3}\.){2}[0-255]{1,3}/ && ($1 <=255)) {

  print "This is a valid ip: $ip \n";
 } else {
   print "This is not a valid ip: $ip \n";
}