refactor(app/inbound): remove unused GatewayIdentityRequired (#4483)

* refactor(app/inbound): remove unused `GatewayIdentityRequired`

this type is never constructed. accordingly, it can be removed.

this was added in #1237
originally, but today it is only checked for as an underlying cause of
boxed errors. it is never constructed, and thus can't be the cause of
any errors.

#2210 later removed the
construction of these types while refactoring our stack target types,
but this was not identified because of our `is_caused_by()` calls.

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): remove unused `SyntheticHttpResponse::unauthenticated()`

#4483 (comment)

Co-Authored-By: Co-authored-by: Alejandro Martinez Ruiz <amr@buoyant.io>
Signed-off-by: katelyn martin <kate@buoyant.io>

---------

Signed-off-by: katelyn martin <kate@buoyant.io>
Co-authored-by: Co-authored-by: Alejandro Martinez Ruiz <amr@buoyant.io>

Author: cratelyn

linkerd/app/core/src/errors/respond.rs

@@ -125,16 +125,6 @@ impl SyntheticHttpResponse {
         }
     }
 
-    pub fn unauthenticated(msg: impl ToString) -> Self {
-        Self {
-            http_status: http::StatusCode::FORBIDDEN,
-            grpc_status: tonic::Code::Unauthenticated,
-            close_connection: false,
-            message: Cow::Owned(msg.to_string()),
-            location: None,
-        }
-    }
-
     pub fn permission_denied(msg: impl ToString) -> Self {
         Self {
             http_status: http::StatusCode::FORBIDDEN,

linkerd/app/inbound/src/http/server.rs

@@ -210,9 +210,6 @@ impl errors::HttpRescue<Error> for ServerRescue {
         if errors::is_caused_by::<crate::GatewayDomainInvalid>(&*error) {
             return Ok(errors::SyntheticHttpResponse::not_found(error));
         }
-        if errors::is_caused_by::<crate::GatewayIdentityRequired>(&*error) {
-            return Ok(errors::SyntheticHttpResponse::unauthenticated(error));
-        }
         if errors::is_caused_by::<crate::GatewayLoop>(&*error) {
             return Ok(errors::SyntheticHttpResponse::loop_detected(error));
         }

linkerd/app/inbound/src/lib.rs

@@ -82,10 +82,6 @@ pub struct GatewayAddr(pub NameAddr);
 // The inbound HTTP server handles gateway traffic; so gateway error types are defined here (so that
 // error metrics can be recorded properly).
 
-#[derive(Debug, Error)]
-#[error("no identity provided")]
-pub struct GatewayIdentityRequired;
-
 #[derive(Debug, Error)]
 #[error("bad gateway domain")]
 pub struct GatewayDomainInvalid;

linkerd/app/inbound/src/metrics/error.rs

@@ -4,7 +4,7 @@ mod tcp;
 pub(crate) use self::{http::HttpErrorMetrics, tcp::TcpErrorMetrics};
 use crate::{
     policy::{HttpRouteNotFound, HttpRouteUnauthorized, ServerUnauthorized},
-    GatewayDomainInvalid, GatewayIdentityRequired, GatewayLoop,
+    GatewayDomainInvalid, GatewayLoop,
 };
 use linkerd_app_core::{
     errors::{FailFastError, LoadShedError},
@@ -19,7 +19,6 @@ enum ErrorKind {
     FailFast,
     LoadShed,
     GatewayDomainInvalid,
-    GatewayIdentityRequired,
     GatewayLoop,
     Io,
     TlsDetectTimeout,
@@ -46,8 +45,6 @@ impl ErrorKind {
             Some(ErrorKind::TlsDetectTimeout)
         } else if err.is::<GatewayDomainInvalid>() {
             Some(ErrorKind::GatewayDomainInvalid)
-        } else if err.is::<GatewayIdentityRequired>() {
-            Some(ErrorKind::GatewayIdentityRequired)
         } else if err.is::<GatewayLoop>() {
             Some(ErrorKind::GatewayLoop)
         } else if err.is::<LoadShedError>() {
@@ -69,7 +66,6 @@ impl FmtLabels for ErrorKind {
                 ErrorKind::LoadShed => "loadshed",
                 ErrorKind::FailFast => "failfast",
                 ErrorKind::TlsDetectTimeout => "tls detection timeout",
-                ErrorKind::GatewayIdentityRequired => "gateway identity required",
                 ErrorKind::GatewayLoop => "gateway loop",
                 ErrorKind::GatewayDomainInvalid => "gateway domain invalid",
                 ErrorKind::Io => "i/o",