add (back) query_trusted_key_servers_first w/ additional configuration detail

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/config/mod.rs

@@ -490,6 +490,35 @@ pub struct Config {
 	#[serde(default = "default_trusted_servers")]
 	pub trusted_servers: Vec<OwnedServerName>,
 
+	/// Whether to query the servers listed in trusted_servers first or query
+	/// the origin server first. For best security, querying the origin server
+	/// first is advised to minimize the exposure to a compromised trusted
+	/// server. For maximum performance this can be set to true, however other
+	/// options exist to query trusted servers first under specific high-load
+	/// circumstances and should be evaluated before setting this to true.
+	#[serde(default)]
+	pub query_trusted_key_servers_first: bool,
+
+	/// Whether to query the servers listed in trusted_servers first
+	/// specifically on room joins. This option limits the exposure to a
+	/// compromised trusted server to room joins only. The join operation
+	/// requires gathering keys from many origin servers which can cause
+	/// significant delays. Therefor this defaults to true to mitigate
+	/// unexpected delays out-of-the-box. The security-paranoid or those
+	/// willing to tolerate delays are advised to set this to false. Note that
+	/// setting query_trusted_key_servers_first to true causes this option to
+	/// be ignored.
+	#[serde(default = "true_fn")]
+	pub query_trusted_key_servers_first_on_join: bool,
+
+	/// Only query trusted servers for keys and never the origin server. This is
+	/// intended for clusters or custom deployments using their trusted_servers
+	/// as forwarding-agents to cache and deduplicate requests. Notary servers
+	/// do not act as forwarding-agents by default, therefor do not enable this
+	/// unless you know exactly what you are doing.
+	#[serde(default)]
+	pub only_query_trusted_key_servers: bool,
+
 	/// max log level for conduwuit. allows debug, info, warn, or error
 	/// see also: https://docs.rs/tracing-subscriber/latest/tracing_subscriber/filter/struct.EnvFilter.html#directives
 	/// **Caveat**: