Class/DhcpOptionObject.psm1
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using module '.\Enums.psm1' # DHCP Option object Class DhcpOptionObject { [byte]$OptionCode [string]$Name [ValidateCount(0, 1024)] Hidden [byte[]]$_Value [ValidateRange(1, 255)] Hidden [byte]$SplitSize = 255 DhcpOptionObject([byte]$OptionCode, [byte[]]$Value) { $this.OptionCode = $OptionCode $this._Value = $Value $this.Name = ($OptionCode -as [DhcpOption]) $this | Add-Member ScriptProperty 'Value' { $this.ParseValue($this._Value) } $this | Add-Member ScriptProperty 'Length' { [byte]$this._Value.Count } } DhcpOptionObject([byte]$OptionCode) { $this.OptionCode = $OptionCode $this._Value = $null $this.Name = ($OptionCode -as [DhcpOption]) $this | Add-Member ScriptProperty 'Value' { $this.ParseValue($this._Value) } $this | Add-Member ScriptProperty 'Length' { [byte]$this._Value.Count } } [byte[]]GetBytes() { $ByteArray = New-Object 'System.Collections.Generic.List[byte]' if ($null -eq $this._Value) { $ByteArray.Add($this.OptionCode) $ByteArray.Add(0) return $ByteArray.ToArray() } else { $Reader = [System.IO.BinaryReader]::new((New-Object IO.MemoryStream(@(, $this._Value)))) try { (1..([math]::Ceiling($this._Value.Count / $this.SplitSize))) | ForEach-Object { $ByteArray.Add($this.OptionCode) $Length = [Math]::Min(($Reader.BaseStream.Length - $Reader.BaseStream.Position), $this.SplitSize) $ByteArray.Add($Length) $ByteArray.AddRange($Reader.ReadBytes($Length)) } } finally { $Reader.Close() } return $ByteArray.ToArray() } } static [DhcpOptionObject]Parse([byte[]]$Bytes) { if ($Bytes.Count -le 2) { throw [System.ArgumentException]::new() } else { $length = $Bytes[1] return [DhcpOptionObject]::new($Bytes[0], $Bytes[ - $length..-1]) } } Hidden [Object] ParseValue([byte[]]$Value) { try { switch ($this.OptionCode -as [DhcpOption]) { { $_ -in ('SubnetMask', 'ServerId', 'RequestedIPAddress') } { # Single IP address return [ipaddress]::new($Value[0..3]) } { $_ -in ('Router', 'TimeServer', 'NameServer', 'DomainNameServer', 'NTPServers', 'NETBIOSNameSrv') } { # Multiple IP addresses $OptionValue = [ipaddress[]]@() for ($i = 0; ($i + 4) -le $Value.Count; $i += 4) { $OptionValue += [ipaddress]::new($Value[$i..($i + 3)]) } return $OptionValue } { $_ -in ('DomainName', 'Hostname', 'ClassId', 'WebProxyAutoDiscovery', 'PCode', 'TCode') } { # String return [string]::new($Value) } { $_ -in ('IPAddressLeaseTime', 'RenewalTime', 'RebindingTime', 'ARPTimeout') } { # TimeSpan (UInt32) # Convert big endian order bytes to UInt32 seconds $Ticks = [int64]([ipaddress]::NetworkToHostOrder([System.BitConverter]::ToInt64(([byte[]]::new(4) + $Value), 0)) * 1e7) return [timespan]::new($Ticks) } TimeOffset { # TimeSpan (Int32) $Ticks = [Int64](([ipaddress]::NetworkToHostOrder([System.BitConverter]::ToInt32($Value, 0))) * 1e7) return [timespan]::new($Ticks) } DomainSearch { # multiple strings # RFC 3397 return [DhcpOptionObject]::ParseDomainSearchList($Value) } SIPServersDHCPOption { # multiple strings or IP addresses # RFC 3361 $Enc = $Value[0] $Data = $Value[1..($Value.Length - 1)] if ($Enc -eq 0) { return [DhcpOptionObject]::ParseDomainSearchList($Data) } else { $OptionValue = [ipaddress[]]@() for ($i = 0; ($i + 4) -le $Data.Count; $i += 4) { $OptionValue += [ipaddress]::new($Data[$i..($i + 3)]) } return $OptionValue } } DHCPMessageType { return ($Value[0] -as [DhcpMessageType]) } Default { return $Value } } } catch {} return $Value } Hidden static [string[]] ParseDomainSearchList([byte[]]$Value) { # Ref: RFC 1035, 3396, 3397 $DomainSearchList = [System.Collections.Generic.List[string]]::new() $Domain = @() $NextPosition = 0 for ($idx = 0; $idx -lt $Value.Length; ) { $Length = $Value[$idx++] if (0 -eq $Length) { # detects end if ($NextPosition -gt $idx) { # back to pointer $idx = $NextPosition } if ($Domain.Count -gt 0) { $DomainSearchList.Add($Domain -join '.') } $Domain = @() continue } elseif ($Length -ge 0xc0) { # detects compression pointer $HigherOctet = (($Length -band 0x3f) -shl 8) if ($idx -lt $Value.Length) { $LowerOctet = $Value[$idx] } else { break } $CPointer = [int]($HigherOctet + $LowerOctet) $NextPosition = ++$idx $idx = $CPointer continue } else { # continue reading $lastIdx = ($idx + $Length - 1) if ($lastIdx -lt $Value.Length) { $Domain += [string]::new($Value[$idx..$lastIdx]) } else { break } $idx += $Length continue } } return $DomainSearchList.ToArray() } Hidden static [byte[]] ConvertDomainSearchListToBytes([string[]]$Domains) { # Ref: RFC 1035, 3397 [byte[]]$Result = $null $IdnMapping = [System.Globalization.IdnMapping]::new() $PointerList = @{} $Writer = [System.IO.BinaryWriter]::new([System.IO.MemoryStream]::new()) try { foreach ($Domain in $Domains) { while (-not [string]::IsNullOrWhiteSpace($Domain)) { # Convert internationalized domain names to Punycode $Domain = $IdnMapping.GetAscii($Domain.Trim("`0", '.').Trim()) if ($PointerList.ContainsKey($Domain)) { if ($PointerList[$Domain] -ge 0 -and $PointerList[$Domain] -le 0x3fff) { # Compression pointer (2 bytes big endian) $Pointer = [System.BitConverter]::GetBytes([ipaddress]::NetworkToHostOrder([Int32]((0xc0 -shl 8) + $PointerList[$Domain])))[2..3] $Writer.Write([byte[]]$Pointer) break } } if ($Domain.IndexOf('.') -le 0) { $PointerList[$Domain] = $Writer.BaseStream.Position $TLDBytes = [System.Text.Encoding]::UTF8.GetBytes($Domain) $Writer.Write([byte]$TLDBytes.Length) $Writer.Write([byte[]]$TLDBytes) # End flag $Writer.Write([byte]0x00) break } else { $PointerList[$Domain] = $Writer.BaseStream.Position $SplitDomain = $Domain.Split('.', 2, 1) $Domain = $SplitDomain[1] $LLD = $SplitDomain[0].Trim("`0").Trim() $LLDBytes = [System.Text.Encoding]::UTF8.GetBytes($LLD) $Writer.Write([byte]$LLDBytes.Length) $Writer.Write([byte[]]$LLDBytes) } } } } finally { $Result = $Writer.BaseStream.ToArray() $Writer.Close() } return $Result } [string] ToString() { return ('{0} ({1})' -f $this.Name, $this.Value) } } |