perl地址转换

#!/usr/bin/perl -w


#### 将十进制数转换成8为二进制
sub dectobin {
substr(unpack("B31",pack("N",shift)) , -8);
}


#### 将32位二进制转换成十进制
sub bintodec {
unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
}


#### 将二进制表示的 IP/子网掩码转换成十进制形式
sub ipmask_bin2dec {
my $prefix = "";
my $result;
map { $result .= $prefix . &bintodec($_); $prefix = ".";
} split (/\./,shift);
return $result;
}


#### 将十进制表示的 IP/子网掩码转换成二进制形式
sub ipmask_dec2bin {
my $prefix = "";
my $result;
map { $result .= $prefix . &dectobin($_); $prefix = ".";
} split (/\./,shift);
return $result;
}


#### 将 CIDR 表示的子网掩码转换成十进制形式
sub ipmask_cidr2dec {
my $cidr_num = shift();
return if ($cidr_num < 0 || $cidr_num > 32);


(my $mask = 1 x $cidr_num . 0 x (32-$cidr_num)) =~
s/(\d{8})(\d{8})(\d{8})(\d{8})/$1.$2.$3.$4/;
print "#####$mask####\n";


return &ipmask_bin2dec($mask);
}


my $dec_ip = "192.168.2.1";
my $dec_mask = "255.255.255.128";
my $cidr_num = 25;


#my $bin_ip = &ipmask_dec2bin($dec_ip);
#my $bin_mask = &ipmask_dec2bin($dec_mask);
my $bin_mask2 = &ipmask_cidr2dec($cidr_num);
my $test = &dectobin(32);


print "Decimal IP: $dec_ip\n";
print "Binary IP: $bin_ip\n";
print "Decimal Netmask: $dec_mask\n";
print "Binary Netmask: $bin_mask\n";
print "CIDR Netmask: $cidr_num = $bin_mask2\n";