shell-network/modules/net-utils.mod

#!/bin/bash

# usage:
#  [[ $(host_reachable host.net) ]] && echo sure ||  echo nope
# or
# host_reachable &> /dev/null && echo sure || echo nope
# or

host_reachable () {
# usage:  host_reachable < -F configfile > host < port >    
# reachable returns yes and return 0 
# return 1 - not reachable
# return 2 no method available to try

local host; local config

function try( ) (    
        if [[ $(command -v nmap) ]] && [[ $2 ]]; then
        [[ $(nmap $1 -PN -p $2 | grep open) ]] && echo yes && return 0 || return 1
        fi
        if [[ $(command -v nc) ]] && [[ $2 ]]; then
        [[ $(nc -w 2 $1 $2) ]] && echo yes && return 0 || return 1
        fi
        if [[ $(command -v ping) ]]; then
        ping -c1 -W1 $1 &> /dev/null && echo yes && return 0 || return 1
        fi
        return 2  # return 2 to indicate no method was available
)

[[ $1 = "-F " ]] && { config=$2;shift 2; }
host=$(lookup_host $1 $config)
try $host $2
return $?
}

lookup_host () {
# usage:  lookup_host hostname < configfile >    
local config; local host; local lhost
config=$([[ $2 ]] && echo $2 || echo ${SSH_CONFIG:-$HOME/.ssh/config})
host=$(get_hostname_host $1)
lhost=$($(which ssh) -F $config -G $host | grep -w hostname | cut -d' ' -f2)
[[ $lhost ]] && echo $lhost || echo $host
}

get_hostname_host () {
   # usage: get_hostname_host <user/host> 
   # returns extracted host if passed user@host
   # otherwise return value passed
   #  [[ $1 =~ "@" ]] && { echo $(sed 's/.*@\(.*\)/\1/' <<< "$1");return 0; } 
  local hostname 
  hostname=$(cut -s -d@ -f2 <<< "$1")
  if [[ ! $hostname ]] && type ssh_config_get &>/dev/null ; then
  hostname=$(ssh_config_get -h $1)
  fi
  [[ $hostname ]] && echo $hostname || return 1
}

get_user_host () {
   # [[ $1 =~ "@" ]] && { echo $(sed 's/\(.*\)@.*/\1/' <<< "$1"); return 0; } || return 1
   # usage: get_user_host <user/host> 
   # returns extracted user if passed user@host
   # otherwise returns nothing
   # return 1 no user in string
  local user 
  user=$(cut -s -d@ -f1 <<< "$1")
  if [[ ! $user ]] && type ssh_config_get &>/dev/null ; then
  user=$(ssh_config_get -u $1)
  fi
  [[ $user ]] && echo $user || return 1
  }


valid_ip()
{
    # usage: valid_ip  ip
    # check so see if basic format is correct and all subs or numbers, no returns 2
    # then checks if they are 0 to 254, no returns 1
    # otherwise if good returns "true" and 0
    local  ip=$1
    local res

    if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        OIFS=$IFS
        IFS='.'
        ip=($ip)
        IFS=$OIFS
        [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 \
            && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
          res=$([ $? == 0 ] && echo true)
          [[ $res ]] && { echo $res;return 0; }
          return 1
        fi
    return 2
}

get_domain() {
    # usage:  get_domain fulldomain
    # returns domain.tld
    # exampe:  get_domain  discuss.mydomain.com => returns mydomain.com
local domain
domain=$(echo $1 | awk -F\. '{print $(NF-1) FS $NF}')
echo "$domain"
}

#https://stackoverflow.com/a/44191743
#https://blog.apnic.net/2021/06/17/how-a-small-free-ip-tool-survived/
publicip () {
# if which curl >/dev/null 2>&1; then if curl ipinfo.io/ip 2> /dev/null; then return; fi fi
# if which dig>/dev/null 2>&1; then if dig +short myip.opendns.com @resolver1.opendns.com 2> /dev/null; then return; fi fi
exec 3<>/dev/tcp/icanhazip.com/80 
echo -e 'GET / HTTP/1.0\r\nhost: icanhazip.com\r\n\r' >&3 
while read i
do
 [ "$i" ] && myip="$i" 
done <&3 
echo "$myip"
}

getip () {
[[ ! $1 ]] && return 1
if ip=$(getent ahostsv4 $1); then 
echo $ip | grep STREAM | '{ print $1 ; exit }'
else 
return 2
fi
}