Add metalink support for aria2c (#2560)

This should fix #2480 and fix https://github.com/lukesampson/scoop-extras/issues/1126

lib/autoupdate.ps1

@@ -91,6 +91,33 @@ function find_hash_in_json([String] $url, [String] $basename, [String] $jsonpath
     return format_hash $hash
 }
 
+function find_hash_in_headers([String] $url) {
+    $hash = $null
+
+    try {
+        $req = [System.Net.WebRequest]::Create($url)
+        $req.Referer = (strip_filename $url)
+        $req.AllowAutoRedirect = $false
+        $req.UserAgent = (Get-UserAgent)
+        $req.Timeout = 2000
+        $req.Method = 'HEAD'
+        $res = $req.GetResponse()
+        if(([int]$response.StatusCode -ge 300) -and ([int]$response.StatusCode -lt 400)) {
+            if($res.Headers['Digest'] -match 'SHA-256=([^,]+)' -or $res.Headers['Digest'] -match 'SHA=([^,]+)' -or $res.Headers['Digest'] -match 'MD5=([^,]+)') {
+                $hash = ([System.Convert]::FromBase64String($matches[1]) | ForEach-Object { $_.ToString('x2') }) -join ''
+                debug $hash
+            }
+        }
+        $res.Close()
+    } catch [system.net.webexception] {
+        write-host -f darkred $_
+        write-host -f darkred "URL $url is not valid"
+        return
+    }
+
+    return format_hash $hash
+}
+
 function get_hash_for_app([String] $app, $config, [String] $version, [String] $url, [Hashtable] $substitutions) {
     $hash = $null
 
@@ -131,17 +158,23 @@ function get_hash_for_app([String] $app, $config, [String] $version, [String] $u
         $hash = find_hash_in_textfile $hashfile_url $basename '"$basename":.*?"sha1":\s"([a-fA-F0-9]{40})"'
     }
 
-    if ($hashmode -eq 'extract') {
+    switch ($hashmode) {
+        'extract' {
             $hash = find_hash_in_textfile $hashfile_url $basename $config.find
         }
-
-    if ($hashmode -eq 'json') {
+        'json' {
             $hash = find_hash_in_json $hashfile_url $basename $config.jp
         }
-
-    if ($hashmode -eq 'rdf') {
+        'rdf' {
             $hash = find_hash_in_rdf $hashfile_url $basename
         }
+        'metalink' {
+            $hash = find_hash_in_headers $url
+            if(!$hash) {
+                $hash = find_hash_in_textfile "$url.meta4"
+            }
+        }
+    }
 
     if($hash) {
         # got one!

lib/install.ps1

@@ -190,6 +190,31 @@ function aria_exit_code($exitcode) {
     return $codes[$exitcode]
 }
 
+function get_filename_from_metalink($file) {
+    $bytes = get_magic_bytes_pretty $file ''
+    # check if file starts with '<?xml'
+    if(!($bytes.StartsWith('3c3f786d6c'))) {
+        return $null
+    }
+
+    # Add System.Xml for reading metalink files
+    Add-Type -AssemblyName 'System.Xml'
+    $xr = [System.Xml.XmlReader]::Create($file)
+    $filename = $null
+    try {
+        $xr.ReadStartElement('metalink')
+        if($xr.ReadToFollowing('file') -and $xr.MoveToFirstAttribute()) {
+            $filename = $xr.Value
+        }
+    } catch [System.Xml.XmlException] {
+        return $null
+    } finally {
+        $xr.Close()
+    }
+
+    return $filename
+}
+
 function dl_with_cache_aria2($app, $version, $manifest, $architecture, $dir, $cookies = $null, $use_cache = $true, $check_hash = $true) {
     $data = @{}
     $urls = @(url $manifest $architecture)
@@ -212,6 +237,11 @@ function dl_with_cache_aria2($app, $version, $manifest, $architecture, $dir, $co
         "--console-log-level=warn"
         "--enable-color=false"
         "--no-conf=true"
+        "--follow-metalink=true"
+        "--metalink-preferred-protocol=https"
+        "--min-tls-version=TLSv1.2"
+        "--stop-with-process=$PID"
+        "--continue"
     )
 
     if($cookies) {
@@ -300,6 +330,12 @@ function dl_with_cache_aria2($app, $version, $manifest, $architecture, $dir, $co
 
     foreach($url in $urls) {
 
+        $metalink_filename = get_filename_from_metalink $data.$url.source
+        if($metalink_filename) {
+            Remove-Item $data.$url.source -Force
+            Rename-Item -Force (Join-Path -Path $cachedir -ChildPath $metalink_filename) $data.$url.source
+        }
+
         # run hash checks
         if($check_hash) {
             $manifest_hash = hash_for_url $manifest $url $architecture