Public/ConvertFrom-CommonLog.ps1
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function ConvertFrom-CommonLog { [Cmdletbinding()] param( [Parameter(Mandatory, ValueFromPipeline)] [ValidateNotNullOrEmpty()] [string[]] $InputObject ) begin { # Initialize DNS cache $DnsCache = @{} } process { # Enumerate $InputObject (necessary for pipeline processing) foreach ($Line in $InputObject) { # Check if a single line matches the follow regex if ($Line -match '(?x) ^ # Beginning of the line (?<SourceIp>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}) # IP address \s # field separator \S+ # username provided by identd (deprecated) \s # field separator (?<User>\S+) # username provided by HTTP authentication \s # field separator \[(?<Timestamp>[^]]+)\] # date enclosed in brackets \s # field separator (?<Request>".+") # request enclosed in quotation marks \s # field separator (?<Code>\d+) # HTTP return code \s # field separator (?<Size>\d+|-) # Size of response $ # End of the line ' ) { # Creating a hashtable with a basic set of fields $LogObject = @{ SourceIp = $Matches['SourceIp'] Timestamp = [datetime]::ParseExact($Matches['Timestamp'], 'dd/MMM/yyyy:HH:mm:ss zz00', [System.Globalization.CultureInfo]::InvariantCulture) Request = $Matches['Request'] Code = $Matches['Code'] } # Checking if a user was authenticated using HTTP if ($Matches['User'] -ne '-') { $LogObject.Add('User', $Matches['User']) } # Checking of the response has a size if ($Matches['Size'] -ne '-') { $LogObject.Add('Size', $Matches['Size']) } # Checking if the source IP was already resolved to a name if ($DnsCache.ContainsKey($LogObject['SourceIp'])) { # Retrieve name from cache $SourceName = $DnsCache[$LogObject['SourceIp']] } else { # If not, resolve IP to name $SourceName = Resolve-DnsName -Name $LogObject['SourceIp'] -QuickTimeout -ErrorAction SilentlyContinue | Select-Object -ExpandProperty NameHost # If no name is registered, use source IP If (-Not $SourceName) { $SourceName = $LogObject['SourceIp'] } # Add name to cache $DnsCache.Add($LogObject['SourceIp'], $SourceName) } # Add name to hashtable $LogObject.Add('SourceName', $SourceName) # Convert hashtable to object and output to pipeline [pscustomobject]$LogObject } else { # If matching fails, output a warning Write-Warning "Unable to parse line <$Line>" } } } } |