digy.sh : tame DNS utility dig with reasonable options. Linux bash HOWTO use dig script, get WAN public IP address, check local network status, and contact who is behind sites.

digy.sh

#!/usr/bin/env bash
#              bash 4.1.5(1)     Linux Ubuntu 10.04           Date : 2012-02-17
#
# _______________|  digy : tame DNS utility dig with reasonable options.
#
#           Usage:  digy  [address]  [rev|name|short|mail|all|long|longa|who]
#
#        Examples:     % digy friendfeed.com
#                      69.63.180.52
#                      #  default second argument is 'short'
#                      #
#                      #       With no arguments whatsoever, digy outputs 
#                      #       your public WAN IP address.
#                      #       For LAN info: "digy local"
#  
#                      % digy 69.63.180.52 rev
#                      friendfeed-reservation-02-07-snc1.facebook.com.
#                      #  'rev' for reverse lookup of IPv4 or IPv6 notation.
#                      #  That dot after com actually signifies root-server.
#  
#                      % digy friendfeed.com name
#                      friendfeed-reservation-02-07-snc1.facebook.com.
#  
#                      % digy friendfeed.com long
#                      friendfeed.com. 3325    IN A   69.63.180.52
#                      friendfeed.com. 144937  IN NS  ns6.facebook.com.
#                      friendfeed.com. 144937  IN NS  ns4.facebook.com.
#                      friendfeed.com. 144937  IN NS  ns5.facebook.com.
#                      friendfeed.com. 144937  IN NS  ns3.facebook.com.
#                      friendfeed.com. 144937  IN NS  ns7.facebook.com.
#  
#                      % digy friendfeed.com who
#                      Creation Date: 13-oct-2005
#                      Expiration Date: 13-oct-2019
#                      Administrative Contact:
#                      Facebook, Inc.
#                      1601 Willow Road 
#                      Menlo Park CA 94025
#                      [email protected] +1.6505434800 Fax: +1.6505434800
#                      # output was edited for this example of 'who'.
#  
#
#    Dependencies:  dig   (standard issue from package 'dnsutils' (main))
#                         [assuming herein non-existence of $HOME/.digrc]
#                   curl  (only to discern your own public IP address)
#                   whois (with sed and awk filtering).

#  CHANGE LOG  LATEST version available:   https://bitbucket.org/rsvp/gists/src
#
#  2012-02-17  Add convenience option 'local' as first argument for address 
#                 which gives LAN information. Revise preamble.
#  2012-02-15  Second argument 'who' yields non-verbose domain name 
#                 REGISTRATION RECORD, i.e. who is behind the site.
#  2012-02-14  Use 'name' instead of 'host' as second argument;
#                 Executing digy without any arguments will give your 
#                 public-facing WAN IP address (not your local LAN).
#  2012-02-13  Add examples. Share digy as a gist.
#  2012-02-12  First version to tame dig for readability and error handling.

#           _____ PREAMBLE_v2: settings, variables, and error handling.
#
LC_ALL=POSIX
#      locale means "ASCII, US English, no special rules, 
#      output per ISO and RFC standards." 
#      Esp. use ASCII encoding for glob and sorting characters. 
shopt -s   extglob
#     ^set extended glob for pattern matching.
set -e
#   ^errors checked: immediate exit if a command has non-zero status. 
set -u
#   ^unassigned variables shall be errors.
#    Example of default VARIABLE ASSIGNMENT:  arg1=${1:-'foo'}

addr=${1:-'public'}
opt=${2:-'short'}


program=${0##*/}   #  similar to using basename
memf=$( mktemp /dev/shm/88_${program}_tmp.XXXXXXXXXX )

cleanup () {
     #  Delete temporary files, then optionally exit given status.
     local status=${1:-'0'}
     rm -f $memf
     [ $status = '-1' ] ||  exit $status      #  thus -1 prevents exit.
} #--------------------------------------------------------------------
warn () {
     #  Message with basename to stderr.          Usage: warn "message"
     echo -e "\n !!  ${program}: $1 "  >&2
} #--------------------------------------------------------------------
die () {
     #  Exit with status of most recent command or custom status, after
     #  cleanup and warn.      Usage: command || die "message" [status]
     local status=${2:-"$?"}
     cleanup -1  &&   warn "$1"  &&  exit $status
} #--------------------------------------------------------------------
trap "die 'SIG disruption, but cleanup finished.' 114" 1 2 3 15
#    Cleanup after INTERRUPT: 1=SIGHUP, 2=SIGINT, 3=SIGQUIT, 15=SIGTERM
#
# _______________     ::  BEGIN  Script ::::::::::::::::::::::::::::::::::::::::


get_publicIP () {
     curl -s http://ip.appspot.com                           \
          ||  die "function get_publicIP needs to be fixed."  123
     #    An external observer is needed to get your own public IP address.
     #    Your ISP determines whether it's permanent (probably not).
     #    See notes at the end for alternatives.
} 


case "$addr" in 
   # 'localhost' is a special reserved word for 127.0.0.1
     'local')  ifconfig -a  |  egrep -v 'packets:|collisions:'  \
                            ||  die "ifconfig fail." 125
               #        ^all kernel-resident network interfaces (LAN) shown,
               #         even if they are down. Trim off some details.
               #         E.g. eth0 is the first Ethernet interface.
               #  Unnecessary to proceed any further, so
               cleanup                                                       ;;

    'public')  addr="$( get_publicIP )"
               echo "$addr"
               #    ^in IPv4 or IPv6 notation, depends on get_publicIP.
               #    Then the name is revealed by the rest of this script.
               opt='rev'                                                     ;;

    '--help')  more "$0"  &&  cleanup                                        ;;
     '-h')     more "$0"  &&  cleanup                                        ;;
               #    source is the best documentation :-)
esac



case "$opt" in 

       'rev')  dig +short -x $addr                                           ;;
               #          ^reverse lookup given IPv4 or IPv6 notation.
      'name')  dig +short -x $(dig +short $addr A)                  \
                    ||  die "no parent, so use 'long' option."       117     ;;
               #    get hostname of the A record.
     'short')  dig +short $addr A                                            ;;
               #          type: A (default), ANY, MX, SIG, etc.
      'mail')  dig +short $addr MX                                           ;;
       'all')  dig +short             $addr ANY                     \
                    ||  die "too intrusive, so use 'short' option."  119     ;;
               #   ^short means terse answer, else use 'long' option.

      'long')  dig +nocmd +noquestion +nocomment +nostats $addr ANY \
                    ||  die "too intrusive, so use 'longa' option."  121     ;;
               #    long gives verbose but relevant answer.
               #    some sites may truncate ANY refusing answer, so
     'longa')  dig +nocmd +noquestion +nocomment +nostats $addr A            ;;

       'who')  whois -H $addr                                         \
                  | sed -e 's/^[[:blank:]]*//' -e 's/[[:blank:]]*$//' \
                        -e '/^NA$/d' -e '/^Fax:$/d' -e '/^US$/d'      \
                        -e '/^Name Server:/d'       -e '/^Status:/d'  \
                  | awk 'BEGIN { RS = "\n\n" }                        \
                         /[Cc]ontact:/ || /[Dd]ate:/  {print $0, "\n"}'      ;;
               #     -Hide legal disclaimers, then
               #      sed domain name REGISTRATION record
               #      against nasty invisible blanks before and after 
               #      each line. Eliminate filler info.
               #          awk takes the cleansed "paragraph" as record, 
               #          and pulls out those involving CONTACT or DATE.

           *)  die "undefined second arg: $opt" 113                          ;;
esac > $memf   

               #  Here's what verbose +stats produces:
               #       ;; Query time: 132 msec
               #       ;; SERVER: 192.168.1.254#53(192.168.1.254)
               #       ;; WHEN: Sun Feb 12 13:46:05 2012
               #       ;; MSG SIZE  rcvd: 108
               #  where SERVER refers to the machine which gave answers.
               #  Deemed irrelevant for our purposes.


fixout () {
     egrep -v 'RRSIG' $memf
     #     ^omit these messy lines:
     #      RRSIG is a digital signature of the answer DNS resource record set.        
}


[ -s $memf ] &&  fixout                                                  \
     ||  die "empty answer. Check argments; try 'long' or 'rev' option."  116



cleanup
# _______________ EOS ::  END of Script ::::::::::::::::::::::::::::::::::::::::



#  # _______________ 2012-02-14 NOTES: get_publicIP
#
#  curl -s http://ip.appspot.com
#  #       2012-02-14 incorporated into digy
#  
#  #           _____ Alternative means
#
#  curl -s http://icanhazip.com
#  #    or choose: ipv4.icanhazip.com or ipv6.icanhazip.com
#  #    2011-03-27 run by Rackspace employee Major Hayden.
#  #    2012-02-14 Major Hayden ([email protected])
#  #                             +1-210-370-7667
#  #                             PO Box 901, Cibolo, TX 78108
#
#  lynx -dump checkip.dyndns.org
#  #          corz.org/ip
#  #          ip.uostas.net
#
#  #  google: "my ip address" yields
#  #        Your public IP address is 76.200.xxx.yyy


#  #        _____ 2011-03-03 BUG:  No longer working...
#     curl -s http://whatismyip.org
#     lynx -dump www.whatismyip.com | grep 'Your IP'



#  The first resource record in any Domain Name System (DNS) Zone file 
#  should be a Start of Authority (SOA) resource record. 
#  The SOA resource record indicates that this DNS name server 
#  is the best source of information for the data within this DNS domain. 


#  vim: set fileencoding=utf-8 ff=unix tw=78 ai syn=sh :