Add support for using Invidious through a HTTP Proxy (#4270)

Partially addresses issue 301

src/invidious.cr

@@ -23,6 +23,7 @@ require "kilt"
 require "./ext/kemal_content_for.cr"
 require "./ext/kemal_static_file_handler.cr"
 
+require "http_proxy"
 require "athena-negotiation"
 require "openssl/hmac"
 require "option_parser"

src/invidious/config.cr

@@ -55,6 +55,15 @@ struct ConfigPreferences
   end
 end
 
+struct HTTPProxyConfig
+  include YAML::Serializable
+
+  property user : String
+  property password : String
+  property host : String
+  property port : Int32
+end
+
 class Config
   include YAML::Serializable
 
@@ -129,6 +138,8 @@ class Config
   property host_binding : String = "0.0.0.0"
   # Pool size for HTTP requests to youtube.com and ytimg.com (each domain has a separate pool of `pool_size`)
   property pool_size : Int32 = 100
+  # HTTP Proxy configuration
+  property http_proxy : HTTPProxyConfig? = nil
 
   # Use Innertube's transcripts API instead of timedtext for closed captions
   property use_innertube_for_captions : Bool = false

src/invidious/helpers/crystal_class_overrides.cr

@@ -18,6 +18,40 @@ end
 class HTTP::Client
   property family : Socket::Family = Socket::Family::UNSPEC
 
+  # Override stdlib to automatically initialize proxy if configured
+  #
+  # Accurate as of crystal 1.12.1
+
+  def initialize(@host : String, port = nil, tls : TLSContext = nil)
+    check_host_only(@host)
+
+    {% if flag?(:without_openssl) %}
+      if tls
+        raise "HTTP::Client TLS is disabled because `-D without_openssl` was passed at compile time"
+      end
+      @tls = nil
+    {% else %}
+      @tls = case tls
+             when true
+               OpenSSL::SSL::Context::Client.new
+             when OpenSSL::SSL::Context::Client
+               tls
+             when false, nil
+               nil
+             end
+    {% end %}
+
+    @port = (port || (@tls ? 443 : 80)).to_i
+
+    self.proxy = make_configured_http_proxy_client() if CONFIG.http_proxy
+  end
+
+  def initialize(@io : IO, @host = "", @port = 80)
+    @reconnect = false
+
+    self.proxy = make_configured_http_proxy_client() if CONFIG.http_proxy
+  end
+
   private def io
     io = @io
     return io if io

src/invidious/yt_backend/connection_pool.cr

@@ -26,12 +26,16 @@ struct YoutubeConnectionPool
 
   def client(&)
     conn = pool.checkout
+    # Proxy needs to be reinstated every time we get a client from the pool
+    conn.proxy = make_configured_http_proxy_client() if CONFIG.http_proxy
+
     begin
       response = yield conn
     rescue ex
       conn.close
-      conn = HTTP::Client.new(url)
 
+      conn = HTTP::Client.new(url)
+      conn.proxy = make_configured_http_proxy_client() if CONFIG.http_proxy
       conn.family = CONFIG.force_resolve
       conn.family = Socket::Family::INET if conn.family == Socket::Family::UNSPEC
       conn.before_request { |r| add_yt_headers(r) } if url.host == "www.youtube.com"
@@ -77,3 +81,16 @@ def make_client(url : URI, region = nil, force_resolve : Bool = false, &)
     client.close
   end
 end
+
+def make_configured_http_proxy_client
+  # This method is only called when configuration for an HTTP proxy are set
+  config_proxy = CONFIG.http_proxy.not_nil!
+
+  return HTTP::Proxy::Client.new(
+    config_proxy.host,
+    config_proxy.port,
+
+    username: config_proxy.user,
+    password: config_proxy.password,
+  )
+end