An AWK script to parse ISC dhcpd configuration files into a CSV for use by dcm.pl to load into OpenNetAdmin

dhcpparse.awk

#!/usr/bin/awk -f
# 
# Author: Matt Pascoe - matt@opennetadmin.com 
#
# This awk script is used to extract relavant information from a dhcpd.conf
# config file and build a csv with appropriate fields for passing into
# a dcm.pl module.  This can be used to bootstrap a new database from existing
# site data.  As usual, inspect the output for accuracy.

# Note that for hosts, it will try a reverse lookup on the IP address
# to determine an appropriate dns name
#
# USAGE:
# make this script executable with `chmod +x dhcpparse.awk` and then
#
#   cat dhcpd.conf|./dhcpparse.awk

# set the RECORD SEPARATOR, RS, to "}" ... records span multiple lines
BEGIN {RS="}"}

# TODO: figure out how to skip comment lines without having to use sed first

length($0) > 5 { total++

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

    counter[total] = total

    # if this field matches the word "host"
    if($i ~ /^host$/) {
      type[total] = "host"
      hostname[total]=$(i+1)
      # Remove the trailing { that might be there
      gsub(/{/, "", hostname[total])
    }

    # if this field matches the word "hardware"
    else if($i ~ /^hardware$/) {

      # get rid of the trailing semi-colon
      split($(i+2),arr,";")

      mac[total]=arr[1]
    }

    # if this field matches the word "hardware"
    else if($i ~ /^fixed-address$/) {

      # get rid of the trailing semi-colon
      split($(i+1),arr,";")

      ip[total]=arr[1]
    }

    # if this field matches the word "subnet"
    else if($i ~ /^subnet$/) {

      type[total] = "subnet"
      # get rid of the enclosing quotes
      split($(i+1),arr,"\"")

      subnetip[total]=arr[1]
    }

    # if this field matches the word "netmask"
    else if($i ~ /^netmask$/) {

      subnetmask[total]=$(i+1)
    }

    # if this field matches the word "range"
    else if($i ~ /^range$/) {
      total++
      type[total] = "pool"
      poolstart[total]=$(i+1)
      # get rid of the trailing semi-colon
      split($(i+2),arr,";")
      poolend[total]=arr[1]
    }

    # if this field matches the word "failover"
    if($i ~ /^#failover$/) {
      # get rid of the enclosing quotes
      split($(i+2),arr,"\"")

      failover[total]=arr[2]
    }
  }



  # do a host command reverse lookup on the IP to try and find a dns name
  if( length(ip[total]) > 0 ) {
    command = ("host " ip[total])
    command | getline tmpname
    close(command)
    split(tmpname,n,"pointer")
    
    # trim off leading spaces etc
    gsub(/^[ \t]+/, "", n[2])

    name[total] = substr(n[2],0,length(n[2])-1)
  }

  if( length(name[total]) == 0 ) {
    name[total]="dhcpload-" ip[total]
  }
  

}

# for every entry we captured, display its appropriate info
END { for(entry in counter) {
         if(type[entry] == "subnet") {
             printf("%s,%s,%s,DHCPLOAD-%s\n",\
                 type[entry],subnetip[entry],subnetmask[entry],subnetip[entry])
         }
         if(type[entry] == "pool") {
             printf("%s,%s,%s,%s\n",\
                 type[entry],poolstart[entry],poolend[entry],failover[entry])
         }
         if(type[entry] == "host") {
             printf("%s,%s,%s,%s,%s\n",\
                 type[entry],ip[entry],mac[entry],name[entry],hostname[entry])
         }
    }
}