HostsFile.psm1
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#region Internals $script:hostFilePath = if ($PSEdition -eq 'Desktop' -or $IsWindows) { "$($env:SystemRoot)\System32\drivers\etc\hosts" } elseif ($PSEdition -eq 'Core' -and $IsLinux) { '/etc/hosts' } $type = @' using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace System.Net { public class HostRecord { private IPAddress ipAddress; private string hostName; public IPAddress IpAddress { get { return ipAddress; } set { ipAddress = value; } } public string HostName { get { return hostName; } set { hostName = value; } } public HostRecord(IPAddress ipAddress, string hostName) { this.ipAddress = ipAddress; this.hostName = hostName; } public HostRecord(string ipAddress, string hostName) { this.ipAddress = IPAddress.Parse(ipAddress); this.hostName = hostName; } public override string ToString() { return string.Format("{0}\t{1}", this.ipAddress.ToString(), this.hostName); } public override bool Equals(object obj) { if (GetType() != obj.GetType()) return false; var otherObject = (HostRecord)obj; if (this.hostName != otherObject.hostName) return false; return this.ipAddress.Equals(otherObject.ipAddress); } public override int GetHashCode() { return this.hostName.GetHashCode() ^ this.ipAddress.GetHashCode(); } } } '@ #endregion Internals Add-Type -TypeDefinition $type -PassThru #region Get-HostFile function Get-HostFile { [CmdletBinding()] param ( [switch]$SuppressOutput, [string]$Section ) $hostContent = New-Object -TypeName System.Collections.ArrayList $hostEntries = New-Object -TypeName System.Collections.ArrayList Write-PSFMessage "Opening file '$script:hostFilePath'" $currentHostContent = (Get-Content -Path $script:hostFilePath) if ($currentHostContent) { $currentHostContent = $currentHostContent.ToLower() } if ($Section) { $startMark = ("#$Section - start").ToLower() $endMark = ("#$Section - end").ToLower() if (($currentHostContent | Where-Object { $_ -eq $startMark }) -and ($currentHostContent | Where-Object { $_ -eq $endMark })) { $startPosition = $currentHostContent.IndexOf($startMark) + 1 $endPosition = $currentHostContent.IndexOf($endMark) - 1 $currentHostContent = $currentHostContent[$startPosition..$endPosition] } else { $currentHostContent = '' } } if ($currentHostContent) { $hostContent.AddRange($currentHostContent) foreach ($entry in $currentHostContent) { $hostfileIpAddress = [System.Text.RegularExpressions.Regex]::Matches($entry, '^(([2]([0-4][0-9]|[5][0-5])|[0-1]?[0-9]?[0-9])[.]){3}(([2]([0-4][0-9]|[5][0-5])|[0-1]?[0-9]?[0-9]))')[0].Value $hostfileHostName = [System.Text.RegularExpressions.Regex]::Matches($entry, '[\w\.-]+$')[0].Value if ($entry -notmatch '^(([2]([0-4][0-9]|[5][0-5])|[0-1]?[0-9]?[0-9])[.]){3}(([2]([0-4][0-9]|[5][0-5])|[0-1]?[0-9]?[0-9]))[\t| ]+[\w\.-]+') { continue } if (-not $hostfileIpAddress -or -not $hostfileHostName) { #could not get the IP address or hostname from current line continue } $newEntry = New-Object System.Net.HostRecord($hostfileIpAddress, $hostfileHostName.ToLower()) $null = $hostEntries.Add($newEntry) } } Write-PSFMessage "File loaded with $($hostContent.Count) lines" $hostContent, $hostEntries } #endregion Get-HostFile #region Get-HostEntry function Get-HostEntry { [CmdletBinding()] param ( [Parameter(ParameterSetName = 'ByHostName')] [ValidateNotNullOrEmpty()][string]$HostName, [Parameter(ParameterSetName = 'ByIpAddress')] [ValidateNotNullOrEmpty()] [System.Net.IPAddress]$IpAddress, [Parameter()] [string]$Section ) if ($Section) { $hostContent, $hostEntries = Get-HostFile -Section $Section } else { $hostContent, $hostEntries = Get-HostFile } if ($HostName) { $results = $hostEntries | Where-Object HostName -eq $HostName $hostEntries | Where-Object HostName -eq $HostName } elseif ($IpAddress) { $results = $hostEntries | Where-Object IpAddress -contains $IpAddress if (($results).count -gt 1) { Write-ScreenInfo -Message "More than one entry found in hosts file with IP address '$IpAddress' (host names: $($results.Hostname -join ','). Returning the last entry" -Type Warning } @($hostEntries | Where-Object IpAddress -contains $IpAddress)[-1] } else { $hostEntries } } #endregion Get-HostEntry #region Add-HostEntry function Add-HostEntry { [CmdletBinding()] param ( [Parameter(Mandatory, ParameterSetName = 'ByString')] [System.Net.IPAddress]$IpAddress, [Parameter(Mandatory, ParameterSetName = 'ByString')] $HostName, [Parameter(Mandatory, ParameterSetName = 'ByHostEntry')] $InputObject, [Parameter(Mandatory)] [string]$Section ) if (-not $InputObject) { $InputObject = New-Object System.Net.HostRecord $IpAddress, $HostName.ToLower() } $hostContent, $hostEntries = Get-HostFile if ($hostEntries.Contains($InputObject)) { return $false } if (($hostEntries | Where-Object HostName -eq $HostName) -and ($hostEntries | Where-Object HostName -eq $HostName).IpAddress.IPAddressToString -ne $IpAddress) { throw "Trying to add entry to hosts file with name '$HostName'. There is already another entry with this name pointing to another IP address." } $startMark = ("#$Section - start").ToLower() $endMark = ("#$Section - end").ToLower() if (-not ($hostContent | Where-Object { $_ -eq $startMark })) { $hostContent.Add($startMark) | Out-Null $hostContent.Add($endMark) | Out-Null } $hostContent.Insert($hostContent.IndexOf($endMark), $InputObject.ToString().ToLower()) $hostEntries.Add($InputObject.ToString().ToLower()) | Out-Null $hostContent | Out-File -FilePath $script:hostFilePath return $true } #endregion Add-HostEntry #region Remove-HostEntry function Remove-HostEntry { [CmdletBinding()] param ( [Parameter(Mandatory, ParameterSetName = 'ByIpAddress')] [System.Net.IPAddress]$IpAddress, [Parameter(Mandatory, ParameterSetName = 'ByHostName')] $HostName, [Parameter(Mandatory, ParameterSetName = 'ByHostEntry')] $InputObject, [Parameter(Mandatory)] [string]$Section ) if (-not $InputObject -and -not $IpAddress -and -not $HostName) { return } if ($InputObject) { $entriesToRemove = $InputObject } else { if (-not $InputObject -and ($IpAddress -or $HostName)) { $entriesToRemove = Get-HostEntry @PSBoundParameters } } if (-not $entriesToRemove) { Write-Error "Trying to remove entry '$HostName' from hosts file. However, there is no entry by that name in this file" } $hostContent, $hostEntries = Get-HostFile -SuppressOutput $startMark = ("#$Section - start").ToLower() if (-not ($hostContent | Where-Object { $_ -eq $startMark })) { Write-Error "Trying to remove entry '$HostName' from hosts file. However, there is no section named '$Section' defined in the hosts file which is a requirement for removing entries from this." return } elseif ($entriesToRemove.Count -gt 1) { Write-Error "Trying to remove entry '$HostName' from hosts file. However, there are more than one entry with this name in the hosts file. Please remove this entry manually." return } if ($entriesToRemove) { $entryToRemove = ($hostContent -match "^($($entriesToRemove.IpAddress))[\t| ]+$($entriesToRemove.HostName)")[0] $entryToRemoveIndex = $hostContent.IndexOf($entryToRemove) $hostContent.RemoveAt($entryToRemoveIndex) $hostEntries.Remove($entriesToRemove) $hostContent | Out-File -FilePath $script:hostFilePath } } #endregion Remove-HostEntry #region function Clear-HostFile function Clear-HostFile { [CmdletBinding()] param ( [Parameter(Mandatory)] [string]$Section ) $hostContent, $hostEntries = Get-HostFile $startMark = ("#$Section - start").ToLower() $endMark = ("#$Section - end").ToLower() $startPosition = $hostContent.IndexOf($startMark) $endPosition = $hostContent.IndexOf($endMark) if ($startPosition -eq -1 -and $endPosition - 1) { Write-Error "Trying to remove all entries for lab from host file. However, there is no section named '$Section' defined in the hosts file which is a requirement for removing entries from this." return } $hostContent.RemoveRange($startPosition, $endPosition - $startPosition + 1) $hostContent | Out-File -FilePath $script:hostFilePath } #endregion function Clear-HostFile |