add config to decrypt on demand instead of polling

src/invidious.cr

@@ -168,7 +168,11 @@ end
 Invidious::Jobs.register Invidious::Jobs::RefreshChannelsJob.new(PG_DB, logger, config)
 Invidious::Jobs.register Invidious::Jobs::RefreshFeedsJob.new(PG_DB, logger, config)
 Invidious::Jobs.register Invidious::Jobs::SubscribeToFeedsJob.new(PG_DB, logger, config, HMAC_KEY)
-Invidious::Jobs.register Invidious::Jobs::UpdateDecryptFunctionJob.new
+
+DECRYPT_FUNCTION = DecryptFunction.new(CONFIG.decrypt_polling)
+if config.decrypt_polling
+  Invidious::Jobs.register Invidious::Jobs::UpdateDecryptFunctionJob.new(logger)
+end
 
 if config.statistics_enabled
   Invidious::Jobs.register Invidious::Jobs::StatisticsRefreshJob.new(PG_DB, config, SOFTWARE)
@@ -191,8 +195,6 @@ def popular_videos
   Invidious::Jobs::PullPopularVideosJob::POPULAR_VIDEOS.get
 end
 
-DECRYPT_FUNCTION = Invidious::Jobs::UpdateDecryptFunctionJob::DECRYPT_FUNCTION
-
 before_all do |env|
   preferences = begin
     Preferences.from_json(env.request.cookies["PREFS"]?.try &.value || "{}")

src/invidious/helpers/helpers.cr

@@ -67,6 +67,7 @@ class Config
   property channel_threads : Int32                 # Number of threads to use for crawling videos from channels (for updating subscriptions)
   property feed_threads : Int32                    # Number of threads to use for updating feeds
   property db : DBConfig                           # Database configuration
+  property decrypt_polling : Bool = true           # Use polling to keep decryption function up to date
   property full_refresh : Bool                     # Used for crawling channels: threads should check all videos uploaded by a channel
   property https_only : Bool?                      # Used to tell Invidious it is behind a proxy, so links to resources should be https://
   property hmac_key : String?                      # HMAC signing key for CSRF tokens and verifying pubsub subscriptions

src/invidious/helpers/signatures.cr

@@ -1,6 +1,17 @@
 alias SigProc = Proc(Array(String), Int32, Array(String))
 
-def fetch_decrypt_function(id = "CvFH_6DNRCY")
+struct DecryptFunction
+  @decrypt_function = [] of {SigProc, Int32}
+  @decrypt_time = Time.monotonic
+
+  def initialize(@use_polling = true)
+  end
+
+  def update_decrypt_function
+    @decrypt_function = fetch_decrypt_function
+  end
+
+  private def fetch_decrypt_function(id = "CvFH_6DNRCY")
     document = YT_POOL.client &.get("/watch?v=#{id}&gl=US&hl=en").body
     url = document.match(/src="(?<url>\/s\/player\/[^\/]+\/player_ias[^\/]+\/en_US\/base.js)"/).not_nil!["url"]
     player = YT_POOL.client &.get(url).body
@@ -45,9 +56,18 @@ def decrypt_signature(fmt : Hash(String, JSON::Any))
 
     sp = fmt["sp"].as_s
     sig = fmt["s"].as_s.split("")
-  DECRYPT_FUNCTION.each do |proc, value|
+    if !@use_polling
+      now = Time.monotonic
+      if now - @decrypt_time > 60.seconds || @decrypt_function.size == 0
+        @decrypt_function = fetch_decrypt_function
+        @decrypt_time = Time.monotonic
+      end
+    end
+
+    @decrypt_function.each do |proc, value|
       sig = proc.call(sig, value)
     end
 
     return "&#{sp}=#{sig.join("")}"
   end
+end

src/invidious/jobs/update_decrypt_function_job.cr

@@ -1,15 +1,15 @@
 class Invidious::Jobs::UpdateDecryptFunctionJob < Invidious::Jobs::BaseJob
-  DECRYPT_FUNCTION = [] of {SigProc, Int32}
+  private getter logger : Invidious::LogHandler
+
+  def initialize(@logger)
+  end
 
   def begin
     loop do
       begin
-        decrypt_function = fetch_decrypt_function
-        DECRYPT_FUNCTION.clear
-        decrypt_function.each { |df| DECRYPT_FUNCTION << df }
+        DECRYPT_FUNCTION.update_decrypt_function
       rescue ex
-        # TODO: Log error
-        next
+        logger.error("UpdateDecryptFunctionJob : #{ex.message}")
       ensure
         sleep 1.minute
         Fiber.yield

src/invidious/videos.cr

@@ -580,7 +580,7 @@ struct Video
         s.each do |k, v|
           fmt[k] = JSON::Any.new(v)
         end
-        fmt["url"] = JSON::Any.new("#{fmt["url"]}#{decrypt_signature(fmt)}")
+        fmt["url"] = JSON::Any.new("#{fmt["url"]}#{DECRYPT_FUNCTION.decrypt_signature(fmt)}")
       end
 
       fmt["url"] = JSON::Any.new("#{fmt["url"]}&host=#{URI.parse(fmt["url"].as_s).host}")
@@ -599,7 +599,7 @@ struct Video
         s.each do |k, v|
           fmt[k] = JSON::Any.new(v)
         end
-        fmt["url"] = JSON::Any.new("#{fmt["url"]}#{decrypt_signature(fmt)}")
+        fmt["url"] = JSON::Any.new("#{fmt["url"]}#{DECRYPT_FUNCTION.decrypt_signature(fmt)}")
       end
 
       fmt["url"] = JSON::Any.new("#{fmt["url"]}&host=#{URI.parse(fmt["url"].as_s).host}")