SigHelper: Make signature server optional and configurable

src/invidious.cr

@@ -153,6 +153,15 @@ Invidious::Database.check_integrity(CONFIG)
   {% puts "\nDone checking player dependencies, now compiling Invidious...\n" %}
 {% end %}
 
+# Misc
+
+DECRYPT_FUNCTION =
+  if sig_helper_address = CONFIG.signature_server.presence
+    IV::DecryptFunction.new(sig_helper_address)
+  else
+    nil
+  end
+
 # Start jobs
 
 if CONFIG.channel_threads > 0

src/invidious/config.cr

@@ -118,6 +118,10 @@ class Config
   # Connect to YouTube over 'ipv6', 'ipv4'. Will sometimes resolve fix issues with rate-limiting (see https://github.com/ytdl-org/youtube-dl/issues/21729)
   @[YAML::Field(converter: Preferences::FamilyConverter)]
   property force_resolve : Socket::Family = Socket::Family::UNSPEC
+
+  # External signature solver server socket (either a path to a UNIX domain socket or "<IP>:<Port>")
+  property signature_server : String? = nil
+
   # Port to listen for connections (overridden by command line argument)
   property port : Int32 = 3000
   # Host to bind (overridden by command line argument)

src/invidious/helpers/sig_helper.cr

@@ -72,8 +72,12 @@ module Invidious::SigHelper
   #  High-level functions
   # ----------------------
 
-  module Client
-    extend self
+  class Client
+    @mux : Multiplexor
+
+    def initialize(uri_or_path)
+      @mux = Multiplexor.new(uri_or_path)
+    end
 
     # Forces the server to re-fetch the YouTube player, and extract the necessary
     # components from it (nsig function code, sig function code, signature timestamp).
@@ -148,7 +152,7 @@ module Invidious::SigHelper
     end
 
     private def send_request(request : Request, &)
-      channel = Multiplexor::INSTANCE.send(request)
+      channel = @mux.send(request)
       slice = channel.receive
       return yield slice
     rescue ex
@@ -172,10 +176,8 @@ module Invidious::SigHelper
 
     @conn : Connection
 
-    INSTANCE = new("")
-
-    def initialize(url : String)
-      @conn = Connection.new(url)
+    def initialize(uri_or_path)
+      @conn = Connection.new(uri_or_path)
       listen
     end
 
@@ -275,13 +277,14 @@ module Invidious::SigHelper
     {% end %}
 
     def initialize(host_or_path : String)
-      if host_or_path.empty?
-        host_or_path = "/tmp/inv_sig_helper.sock"
-      end
-
       case host_or_path
       when .starts_with?('/')
-        @socket = UNIXSocket.new(host_or_path)
+        # Make sure that the file exists
+        if File.exists?(host_or_path)
+          @socket = UNIXSocket.new(host_or_path)
+        else
+          raise Exception.new("SigHelper: '#{host_or_path}' no such file")
+        end
       when .starts_with?("tcp://")
         uri = URI.parse(host_or_path)
         @socket = TCPSocket.new(uri.host.not_nil!, uri.port.not_nil!)

src/invidious/helpers/signatures.cr

@@ -1,10 +1,11 @@
 require "http/params"
 require "./sig_helper"
 
-struct Invidious::DecryptFunction
+class Invidious::DecryptFunction
   @last_update : Time = Time.utc - 42.days
 
-  def initialize
+  def initialize(uri_or_path)
+    @client = SigHelper::Client.new(uri_or_path)
     self.check_update
   end
 
@@ -16,19 +17,18 @@ struct Invidious::DecryptFunction
 
     # Get the time when the player was updated, in the event where
     # multiple invidious processes are run in parallel.
-    player_ts = Invidious::SigHelper::Client.get_player_timestamp
-    player_time = Time.unix(player_ts || 0)
+    player_time = Time.unix(@client.get_player_timestamp || 0)
 
     if (now - player_time) > 5.minutes
       LOGGER.debug("Signature: Player might be outdated, updating")
-      Invidious::SigHelper::Client.force_update
+      @client.force_update
       @last_update = Time.utc
     end
   end
 
   def decrypt_nsig(n : String) : String?
     self.check_update
-    return SigHelper::Client.decrypt_n_param(n)
+    return @client.decrypt_n_param(n)
   rescue ex
     LOGGER.debug(ex.message || "Signature: Unknown error")
     LOGGER.trace(ex.inspect_with_backtrace)
@@ -37,7 +37,7 @@ struct Invidious::DecryptFunction
 
   def decrypt_signature(str : String) : String?
     self.check_update
-    return SigHelper::Client.decrypt_sig(str)
+    return @client.decrypt_sig(str)
   rescue ex
     LOGGER.debug(ex.message || "Signature: Unknown error")
     LOGGER.trace(ex.inspect_with_backtrace)
@@ -46,7 +46,7 @@ struct Invidious::DecryptFunction
 
   def get_sts : UInt64?
     self.check_update
-    return SigHelper::Client.get_signature_timestamp
+    return @client.get_signature_timestamp
   rescue ex
     LOGGER.debug(ex.message || "Signature: Unknown error")
     LOGGER.trace(ex.inspect_with_backtrace)

src/invidious/videos.cr

@@ -1,5 +1,3 @@
-private DECRYPT_FUNCTION = IV::DecryptFunction.new
-
 enum VideoType
   Video
   Livestream
@@ -108,14 +106,14 @@ struct Video
 
       LOGGER.debug("Videos: Decoding '#{cfr}'")
 
-      unsig = DECRYPT_FUNCTION.decrypt_signature(cfr["s"])
+      unsig = DECRYPT_FUNCTION.try &.decrypt_signature(cfr["s"])
       params[sp] = unsig if unsig
     else
       url = URI.parse(fmt["url"].as_s)
       params = url.query_params
     end
 
-    n = DECRYPT_FUNCTION.decrypt_nsig(params["n"])
+    n = DECRYPT_FUNCTION.try &.decrypt_nsig(params["n"])
     params["n"] = n if n
 
     params["host"] = url.host.not_nil!

src/invidious/yt_backend/youtube_api.cr

@@ -2,8 +2,6 @@
 # This file contains youtube API wrappers
 #
 
-private STS_FETCHER = IV::DecryptFunction.new
-
 module YoutubeAPI
   extend self
 
@@ -462,7 +460,7 @@ module YoutubeAPI
     } of String => String | Int64
 
     if {"WEB", "TVHTML5"}.any? { |s| client_config.name.starts_with? s }
-      if sts = STS_FETCHER.get_sts
+      if sts = DECRYPT_FUNCTION.try &.get_sts
         playback_ctx["signatureTimestamp"] = sts.to_i64
       end
     end