Perfilador de scripts de PowerShell actualizado

El año pasado escribí una barra lateral para Ed Wilson, el encargado de secuencias de comandos, y una actualización de su libro Mejores prácticas de PowerShell. Escribí un script usando el nuevo analizador en PowerShell 3.0 para analizar un script y preparar un informe que mostrara qué comandos ejecutaría, los parámetros necesarios y cualquier cosa que pudiera representar un peligro. También escribí un artículo con el guión para el blog Hey Scripting Guy.

Durante mi clase de capacitación de PowerShell la semana pasada, estuvimos hablando sobre cómo mirar el código de otra persona y descubrir qué podría hacer. También demostré mi guión. Durante el transcurso de esa demostración me di cuenta de que necesitaba hacer algunas revisiones. Aquí está la versión 2 de Get-ASTScriptProfile.ps1.


#requires -version 3.0

#Get-ASTScriptProfile.ps1

<#
  ****************************************************************
  * DO NOT USE IN A PRODUCTION ENVIRONMENT UNTIL YOU HAVE TESTED *
  * THOROUGHLY IN A LAB ENVIRONMENT. USE AT YOUR OWN RISK.  IF   *
  * YOU DO NOT UNDERSTAND WHAT THIS SCRIPT DOES OR HOW IT WORKS, *
  * DO NOT USE IT OUTSIDE OF A SECURE, TEST SETTING.             *
  ****************************************************************
#>

<#
.Synopsis
Profile a PowerShell Script
.Description
This script will parse a PowerShell script using the AST to identify elements 
and any items that might be dangerous. The output is a text report which by 
default is turned into a help topic stored in your Windows PowerShell folder
under Documents, although you can specify an alternate location.

DETAILS
The script takes the name of a script to profile. You can specify a ps1 or 
psm1 filename. Using the AST the script will prepare a text report showing 
you any script requirements, script parameters, commands and type names. You 
will see all commands used including those that can't be resolved as well as 
those that I thought might be considered potentially dangerous such as cmdlets 
that use the verbs Remove or Stop. Because some people might invoke methods 
from .NET classes directly I've also captured all typenames. Most of them will
probably be related to parameters but as least you'll know what to look for. 

The report won't detail parameters from nested functions but you'll still see 
what commands they will use. The script uses Get-Command to identify commands 
which might entail loading a module. Most of the time this shouldn't be an 
issue but you still might want to profile the script in virtualized or test 
environment. 

Any unresolved command you see is either from a module that couldn't be loaded
or it might be an internally defined command. Once you know what to look for 
you can open the script in your favorite editor and search for the mystery 
commands.

Note that if the script uses application names like Main or Control for function
names, they might be misinterpreted. In that case, search the script for the name,
ie "main". 

This version will only analyze files with an extension of .ps1, .psm1 or .txt.
.Parameter Path
The path to the script file. It should have an extension of .ps1, .psm1 or
.bat.
.Parameter FilePath
The path for the report file. The default is your WindowsPowerShell folder.
This paramter has aliases of fp and out.
.Example
PS C:\> c:\scripts\Get-ASTScriptProfile c:\download\UnknownScript.ps1 

This will analyze the script UnknownScript.ps1 and show the results in a
help window. It will also create a text file in your Documents\WindowsPowerShell 
folder called UnknownScript.help.txt.
.Example
PS C:\> c:\scripts\Get-ASTScriptProfile c:\download\UnknownScript.ps1 -filepath c:\work

This command is the same as the first example except the help file will be created
in C:\Work.

.Notes
Version 2.0
Last Updated January 14, 2014
Jeffery Hicks (http://twitter.com/jeffhicks)

Learn more:
 PowerShell in Depth: An Administrator's Guide (http://www.manning.com/jones2/)
 PowerShell Deep Dives (http://manning.com/hicks/)
 Learn PowerShell 3 in a Month of Lunches (http://manning.com/jones3/)
 Learn PowerShell Toolmaking in a Month of Lunches (http://manning.com/jones4/)
 
.Inputs
None
.Outputs
Help topic
.Link
Get-Command
Get-Alias
#>

[cmdletbinding()]
Param(
[Parameter(Position=0,Mandatory,HelpMessage="Enter the path of a PowerShell script")]
[ValidateScript({Test-Path $_})]
[ValidatePattern( "\.(ps1|psm1|txt)$")]
[string]$Path,
[ValidateScript({Test-Path $_})]
[Alias("fp","out")]
[string]$FilePath = "$env:userprofile\Documents\WindowsPowerShell"
)

Write-Verbose "Starting $($myinvocation.MyCommand)"

#region setup profiling
#need to resolve full path and convert it
$Path = (Resolve-Path -Path $Path).Path | Convert-Path
Write-Verbose "Analyzing $Path"

Write-Verbose "Parsing File for AST"
New-Variable astTokens -force
New-Variable astErr -force

$AST = [System.Management.Automation.Language.Parser]::ParseFile($Path,[ref]$astTokens,[ref]$astErr)

#endregion

#region generate AST data

#include PowerShell version information
Write-Verbose "PSVersionTable"
Write-Verbose ($PSversionTable | Out-String)

$report=@"
Script Profile report for: $Path

******************
* PSVersionTable *
******************
$(($PSversionTable | Out-String).TrimEnd())

"@

Write-Verbose "Getting requirements and parameters"
$report+=@"

******************
*  Requirements  *
******************
$(($ast.ScriptRequirements | out-string).Trim())

******************
*  Parameters    *
******************
$(($ast.ParamBlock.Parameters | 
 Select Name,DefaultValue,StaticType,Attributes |
 Format-List | Out-String).Trim())
 
"@

Write-Verbose "Getting all command elements"

$commands = @()
$unresolved = @()

$genericCommands = $astTokens | 
where {$_.tokenflags -eq 'commandname' -AND $_.kind -eq 'generic'} 

$aliases = $astTokens | 
where {$_.tokenflags -eq 'commandname' -AND $_.kind -eq 'identifier'} 

Write-Verbose "Parsing commands"
foreach ($command in $genericCommands) {
    Try {
       $commands+= Get-Command -Name $command.text -ErrorAction Stop
    }
    Catch {
      $unresolved+= $command.Text
    }
}

foreach ($command in $aliases) {
Try {
       $commands+= Get-Command -Name $command.text -erroraction Stop |
       foreach { 
         #get the resolved command
         Get-Command -Name $_.Definition  
       }
    }
    Catch {
        $unresolved+= $command.Text
    }
}

Write-Verbose "All commands"
$report+=@"

******************
*  All Commands  *
******************
$(($Commands | Sort -Unique | Format-Table -autosize | Out-String).Trim())

"@

Write-Verbose "Unresolved commands"
$report+=@"

******************
*  Unresolved    *
******************
$($Unresolved | Sort -Unique | Format-Table -autosize | Out-String)
"@

Write-Verbose "Potentially dangerous commands"
#identify dangerous commands
$danger="Remove","Stop","Disconnect","Suspend","Block",
"Disable","Deny","Unpublish","Dismount","Reset","Resize",
"Rename","Redo","Lock","Hide","Clear"

$danger = $commands | where {$danger -contains $_.verb}

#get type names, some of which may come from parameters
Write-Verbose "Typenames"
$report+=@"

******************
*  TypeNames     *
******************
$($asttokens | where {$_.tokenflags -eq 'TypeName'} | 
Sort @{expression={$_.text.toupper()}} -unique | 
Select -ExpandProperty Text | Out-String)
"@

$report+=@"

******************
*  Warning       *
******************
$($danger | Format-Table -AutoSize | Out-String)
"@

#endregion

Write-Verbose "Display results"
#region create and display the result

#create a help topic file using the script basename
$basename = (Get-Item $Path).basename     
#stored in the Documents folder
$reportFile = Join-Path -Path $FilePath -ChildPath "$basename.help.txt"

Write-Verbose "Saving report to $reportFile"
#insert the Topic line so help recognizes it
"TOPIC" | Out-File -FilePath $reportFile -Encoding ascii 

#create the report
$report | Out-File -FilePath $reportFile -Encoding ascii -Append

#view the report with Get-Help and -ShowWindow
Get-Help (Join-Path -Path $FilePath -ChildPath $basename) -ShowWindow

#endregion

Write-Verbose "Profiling complete."

#end of script

Una cosa que descubrí fue que al AST no le gustaba analizar un archivo sin una ruta absoluta y resuelta. Me encontré con errores porque el script estaba en un PSDrive como Scripts: que se resolvió en C:\Scripts. La solución fue resolverlo, en el caso de utilizar una ruta como .\file.ps1 y luego convertir la ruta.


$Path = (Resolve-Path -Path $Path).Path | Convert-Path

También descubrí que si el script contiene funciones con un nombre como Main o Control, el analizador, al menos de la forma en que lo estoy usando, lo detectará como una aplicación como main.cpl. Hay una razón por la que debes darle a tu función un nombre estándar y significativo y tratar de evitar el uso de un nombre que *podría* ser malinterpretado. Una función llamada Bloc de notas probablemente no sea una buena idea. Modifiqué la ayuda para indicar esta posible interpretación errónea. No estoy seguro de que pueda hacer mucho más.

Los pocos otros cambios que hice fueron por motivos de flexibilidad y claridad. Ahora incluyo la información de PSVersion en el informe. La información de los parámetros ahora se muestra como una lista para evitar perder datos. Agregué un parámetro de validación para el archivo de secuencia de comandos para que solo pueda analizar un archivo .ps1, .psm1 o .txt.

Finalmente, agregué un parámetro para que puedas especificar la carpeta para el archivo de salida. El valor predeterminado es Documentos\WindowsPowerShell. No especifica el nombre del archivo, solo la ruta como C:\Scripts o $env:temp.

PS Scripts:\> .\Get-ASTScriptProfile.ps1 .\Convert-WindowsImage.ps1 -out c:\work

Esto dará como resultado un informe de tema de ayuda como este:

Perfilador de scripts de PowerShell actualizado

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