feat: add a new status code for "external" errors (#4775)

* feat: add a new status code for "external" errors

* Update src/auth/src/error.rs

Co-authored-by: shuiyisong <113876041+shuiyisong@users.noreply.github.com>

* support mysql cli cleartext auth

* resolve PR comments

---------

Co-authored-by: shuiyisong <113876041+shuiyisong@users.noreply.github.com>

src/auth/src/common.rs

@@ -75,6 +75,16 @@ pub enum Password<'a> {
     PgMD5(HashedPassword<'a>, Salt<'a>),
 }
 
+impl Password<'_> {
+    pub fn r#type(&self) -> &str {
+        match self {
+            Password::PlainText(_) => "plain_text",
+            Password::MysqlNativePassword(_, _) => "mysql_native_password",
+            Password::PgMD5(_, _) => "pg_md5",
+        }
+    }
+}
+
 pub fn auth_mysql(
     auth_data: HashedPassword,
     salt: Salt,

src/auth/src/error.rs

@@ -89,7 +89,7 @@ impl ErrorExt for Error {
             Error::FileWatch { .. } => StatusCode::InvalidArguments,
             Error::InternalState { .. } => StatusCode::Unexpected,
             Error::Io { .. } => StatusCode::StorageUnavailable,
-            Error::AuthBackend { .. } => StatusCode::Internal,
+            Error::AuthBackend { source, .. } => source.status_code(),
 
             Error::UserNotFound { .. } => StatusCode::UserNotFound,
             Error::UnsupportedPasswordType { .. } => StatusCode::UnsupportedPasswordType,

src/auth/src/user_provider.rs

@@ -57,6 +57,11 @@ pub trait UserProvider: Send + Sync {
         self.authorize(catalog, schema, &user_info).await?;
         Ok(user_info)
     }
+
+    /// Returns whether this user provider implementation is backed by an external system.
+    fn external(&self) -> bool {
+        false
+    }
 }
 
 fn load_credential_from_file(filepath: &str) -> Result<Option<HashMap<String, Vec<u8>>>> {