Nevergreen

2106.5

Private/Resolve-Uri.ps1

function Resolve-Uri {
    <#
    .SYNOPSIS
        Resolves a URI and also returns the filename and last modified date if found.
 
    .DESCRIPTION
        Resolves a URI and also returns the filename and last modified date if found.
 
    .NOTES
        Site: https://packageology.com
        Author: Dan Gough
        Twitter: @packageologist
 
    .LINK
        https://github.com/DanGough/Nevergreen
 
    .PARAMETER Uri
        The URI resolve. Accepts an array of strings or pipeline input.
 
    .PARAMETER UserAgent
        Optional parameter to provide a user agent for Invoke-WebRequest to use. Examples are:
 
        Googlebot: 'Googlebot/2.1 (+http://www.google.com/bot.html)'
        Microsoft Edge: 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.135 Safari/537.36 Edge/12.246'
 
    .EXAMPLE
        Resolve-Uri -Uri 'http://somewhere.com/somefile.exe'
 
        Description:
        Returns the absolute redirected URI, filename and last modified date.
    #>
    [CmdletBinding(SupportsShouldProcess = $False)]
    param (
        [Parameter(
            Mandatory = $true,
            Position = 0,
            ValueFromPipeline,
            ValueFromPipelineByPropertyName)]
        [ValidatePattern('^(http|https)://')]
        [Alias('Url')]
        [String[]] $Uri,
        [Parameter(
            Mandatory = $false,
            Position = 1)]
        [String] $UserAgent
    )

    begin {
        $ProgressPreference = 'SilentlyContinue'
    }

    process {

        foreach ($UriToResolve in $Uri) {

            try {

                $ParamHash = @{
                    Uri              = $UriToResolve
                    Method           = 'Head'
                    UseBasicParsing  = $True
                    DisableKeepAlive = $True
                    ErrorAction      = 'Stop'
                }

                if ($UserAgent) {
                    $ParamHash.UserAgent = $UserAgent
                }

                $Response = Invoke-WebRequest @ParamHash

                if ($IsCoreCLR) {
                    $ResolvedUri = $Response.BaseResponse.RequestMessage.RequestUri.AbsoluteUri
                }
                else {
                    $ResolvedUri = $Response.BaseResponse.ResponseUri.AbsoluteUri
                }

                Write-Verbose "$($MyInvocation.MyCommand): URI resolved to: $ResolvedUri"

                #PowerShell 7 returns each header value as single unit arrays instead of strings which messes with the -match operator coming up, so use Select-Object:
                $ContentDisposition = $Response.Headers.'Content-Disposition' | Select-Object -First 1

                if ($ContentDisposition -match 'filename="?([^\\/:\*\?"<>\|]+)') {
                    $FileName = $matches[1]
                    Write-Verbose "$($MyInvocation.MyCommand): Content-Disposition header found: $ContentDisposition"
                    Write-Verbose "$($MyInvocation.MyCommand): File name determined from Content-Disposition header: $FileName"
                }
                else {
                    $Slug = [uri]::UnescapeDataString($ResolvedUri.Split('?')[0].Split('/')[-1])
                    if ($Slug -match '^[^\\/:\*\?"<>\|]+\.[^\\/:\*\?"<>\|]+$') {
                        Write-Verbose "$($MyInvocation.MyCommand): URI slug is a valid file name: $FileName"
                        $FileName = $Slug
                    }
                    else {
                        $FileName = $null
                    }
                }

                try {
                    $LastModified = [DateTime]($Response.Headers.'Last-Modified' | Select-Object -First 1)
                    Write-Verbose "$($MyInvocation.MyCommand): Last modified date: $LastModified"
                }
                catch {
                    Write-Verbose "$($MyInvocation.MyCommand): Unable to parse date from last modified header: $($Response.Headers.'Last-Modified')"
                    $LastModified = $null
                }

            }
            catch {
                Write-Verbose "$($MyInvocation.MyCommand): Unable to resolve URI: $_"
            }

            if ($ResolvedUri) {
                [PSCustomObject]@{
                    Uri          = $ResolvedUri
                    FileName     = $FileName
                    LastModified = $LastModified
                }
            }

        }
    }

    end {
    }

}