# ==============================================================================================
# 
# Microsoft PowerShell Source File -- Created with SAPIEN Technologies PrimalScript 2009
# 
# NAME: Parse-Hosts.ps1 
# v1.1
# USAGE: .\parse-hosts.ps1 [[-computername] computername <string>] [-progress]
# 
# AUTHOR: Jeffery Hicks, PowerShell MVP , SAPIEN Technologies, Inc.
# DATE  : 2/27/2009
# 
# COMMENT: This script will connect to a computer's $ADMIN share to parse the HOSTS
# file. Assuming entries are found, a custom object is written to the pipeline with the
# IP Address, name and comment, if any.
# 
# Specifying -progress will use Write-Progress to display what the script is doing.
# For single machines you probably won't see anything but it can be useful if you are 
# running through a list of computers.
#
# The script will first attempt to ping the computer and only continue if a ping succeeds.
#
# DISCLAIMER AND WARNING:
# 	THIS CODE AND INFORMATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
# 	KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# 	IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
#   TEST THOROUGHLY IN A NON-PRODUCTION ENVIRONMENT. IF YOU DON'T KNOW WHAT THIS
#   SCRIPT WILL DO...DO NOT RUN IT!
# 
# ==============================================================================================

Param([string]$computername=$env:computername,
          [switch]$progress)
          
  function TestPing([string]$address) {
	$wmi = Get-WmiObject -query "SELECT * FROM Win32_PingStatus WHERE Address = '$address'"
	if ($wmi.statuscode -eq 0) {
		$true
	} else {
		$false
	}
  }
    
if ($progress) {
    $activity="Analyzing Hosts file"
    $status=("...on {0}" -f $computername.ToUpper())
    Write-Progress -Activity $activity -status $status
}

if (TestPing $computername) {
    #only proceed if computer can be pinged
    $Hosts= "\\$computername\admin$\System32\drivers\etc\hosts"
    if ((Get-Item $Hosts -ea "SilentlyContinue").Exists) {
        #if hosts file is found, then parse it.
        
        if ($progress) {
            $current="Parsing $hosts"
            Write-Progress -Activity $activity -status $status -current $current
        }
        
        #define a regex to return first NON-whitespace character
        [regex]$r="\S"
        #strip out any lines beginning with # and blank lines
        $HostsData = Get-Content $Hosts | where {
         (($r.Match($_)).value -ne "#") -and ($_ -notmatch "^\s+$") -and ($_.Length -gt 0)
         }
        if ($HostsData){
            #only process if something was found in HOSTS
            $HostsData | foreach {
                #created named values
                $_ -match "(?<IP>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})\s+(?<HOSTNAME>\S+)" | Out-Null
                $ip=$matches.ip
                $hostname=$matches.hostname  
                
                #get a comment if defined for the line
                if ($_.contains("#")) {
                    $comment=$_.substring($_.indexof("#")+1)
                }
                else {
                    $comment=$null
                   }
                
                #create a blank object
                $obj = New-Object PSObject
                
                #the computername property could be the name of the computer whose hosts file
                #you are enumerating
                $obj | Add-Member Noteproperty -name "Computername" -Value $computername.ToUpper()
                $obj | Add-Member Noteproperty -name "IP" -Value $ip
                $obj | Add-Member Noteproperty -name "Hostname" -Value $hostname
                $obj | Add-Member Noteproperty -name "Comment" -Value $comment
                
                write $obj
               } #end ForEach
         } #end If $HostsData
         else {
            Write-Host ("{0} has no entries in its HOSTS file." -f $computername.toUpper()) -foreground Magenta
         }
    } #end If Hosts exists
    else {
        Write-Warning "Failed to find $hosts"
      }
 } #end If TestPing
else {
    Write-Warning ("Failed to connect to {0}" -f $computername.ToUpper())
}

if ($progress) {
    Write-Progress -Activity $activity -status $status -completed
  }   
#end of script