split well_known resolver into unit

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

src/service/resolver/well_known.rs

@@ -0,0 +1,49 @@
+use conduwuit::{Result, debug, debug_error, debug_info, debug_warn, implement, trace};
+
+#[implement(super::Service)]
+#[tracing::instrument(name = "well-known", level = "debug", skip(self, dest))]
+pub(super) async fn request_well_known(&self, dest: &str) -> Result<Option<String>> {
+	trace!("Requesting well known for {dest}");
+	let response = self
+		.services
+		.client
+		.well_known
+		.get(format!("https://{dest}/.well-known/matrix/server"))
+		.send()
+		.await;
+
+	trace!("response: {response:?}");
+	if let Err(e) = &response {
+		debug!("error: {e:?}");
+		return Ok(None);
+	}
+
+	let response = response?;
+	if !response.status().is_success() {
+		debug!("response not 2XX");
+		return Ok(None);
+	}
+
+	let text = response.text().await?;
+	trace!("response text: {text:?}");
+	if text.len() >= 12288 {
+		debug_warn!("response contains junk");
+		return Ok(None);
+	}
+
+	let body: serde_json::Value = serde_json::from_str(&text).unwrap_or_default();
+
+	let m_server = body
+		.get("m.server")
+		.unwrap_or(&serde_json::Value::Null)
+		.as_str()
+		.unwrap_or_default();
+
+	if ruma::identifiers_validation::server_name::validate(m_server).is_err() {
+		debug_error!("response content missing or invalid");
+		return Ok(None);
+	}
+
+	debug_info!("{dest:?} found at {m_server:?}");
+	Ok(Some(m_server.to_owned()))
+}