remove namespace check on username login, code simplification on login route

the namespace check on username login is unnecessary, hashes aren't ever
going to match, and axum auth handles this kind of stuff already

Signed-off-by: strawberry <strawberry@puppygock.gay>

src/api/client_server/session.rs

@@ -18,7 +18,7 @@
 	UserId,
 };
 use serde::Deserialize;
-use tracing::{debug, error, info, warn};
+use tracing::{debug, info, warn};
 
 use super::{DEVICE_ID_LENGTH, TOKEN_LENGTH};
 use crate::{services, utils, Error, Result, Ruma};
@@ -76,14 +76,7 @@ pub(crate) async fn login_route(body: Ruma<login::v3::Request>) -> Result<login:
 				warn!("Bad login type: {:?}", &body.login_info);
 				return Err(Error::BadRequest(ErrorKind::forbidden(), "Bad login type."));
 			}
-			.map_err(|e| {
-				warn!("Failed to parse username from user logging in: {e}");
-				Error::BadRequest(ErrorKind::InvalidUsername, "Username is invalid.")
-			})?;
-
-			if services().appservice.is_exclusive_user_id(&user_id).await {
-				return Err(Error::BadRequest(ErrorKind::Exclusive, "User ID reserved by appservice."));
-			}
+			.map_err(|_| Error::BadRequest(ErrorKind::InvalidUsername, "Username is invalid."))?;
 
 			let hash = services()
 				.users
@@ -94,18 +87,15 @@ pub(crate) async fn login_route(body: Ruma<login::v3::Request>) -> Result<login:
 				return Err(Error::BadRequest(ErrorKind::UserDeactivated, "The user has been deactivated"));
 			}
 
-			let Ok(parsed_hash) = PasswordHash::new(&hash) else {
-				error!("error while hashing user {}", user_id);
-				return Err(Error::BadServerResponse("could not hash"));
-			};
+			let parsed_hash = PasswordHash::new(&hash)
+				.map_err(|_| Error::BadServerResponse("Unknown error occurred hashing password."))?;
 
-			let hash_matches = services()
+			if services()
 				.globals
 				.argon
 				.verify_password(password.as_bytes(), &parsed_hash)
-				.is_ok();
-
-			if !hash_matches {
+				.is_err()
+			{
 				return Err(Error::BadRequest(ErrorKind::forbidden(), "Wrong username or password."));
 			}
 
@@ -125,17 +115,10 @@ pub(crate) async fn login_route(body: Ruma<login::v3::Request>) -> Result<login:
 
 				let username = token.claims.sub.to_lowercase();
 
-				let user_id =
-					UserId::parse_with_server_name(username, services().globals.server_name()).map_err(|e| {
-						warn!("Failed to parse username from user logging in: {e}");
-						Error::BadRequest(ErrorKind::InvalidUsername, "Username is invalid.")
-					})?;
-
-				if services().appservice.is_exclusive_user_id(&user_id).await {
-					return Err(Error::BadRequest(ErrorKind::Exclusive, "User ID reserved by appservice."));
-				}
-
-				user_id
+				UserId::parse_with_server_name(username, services().globals.server_name()).map_err(|e| {
+					warn!("Failed to parse username from user logging in: {e}");
+					Error::BadRequest(ErrorKind::InvalidUsername, "Username is invalid.")
+				})?
 			} else {
 				return Err(Error::BadRequest(
 					ErrorKind::Unknown,