Hosts File Validation

validhosts.awk

#!/usr/bin/awk -f



function valid_ip(ip) {

  octets=4

  search="."

  if ( occurances_of_seperator(ip,search) != 3 ) {

  return false

  }

  for (i=1;i<=octets;i++) {

if ( ! valid_int_in_range(array[i],0,255) ) {

  return false

}

  }

  return true

}



function valid_fqdn(fqdn){

  search="."

  return ( occurances_of_seperator(fqdn,search) >= 1)

}



function occurances_of_seperator(string,seperator) {

return split(string,array,seperator) - 1

}



function valid_int_in_range(val,range_min,range_max) {

return ( range_min <= val && val <= range_max)

}



BEGIN { 

print "Starting" 

true=1

false=0

}





!/^($|[:space:]*#)/ { 

ip=$1

fqdn=$2

$1=""

$2=""

aliases=$0



if ( ! valid_ip(ip) ) {

printf("Invalid IP Address on Line number: %s\n",NR)

}

if ( ! valid_fqdn(fqdn) ) {

printf("Invalid  FQDN on Line number: %s\n",NR)

}


}



END { 

print "Ending" 

}