From 56938bcc6b96b221cd05910d2f76316c1216b84f Mon Sep 17 00:00:00 2001
From: Matthew Stevenson <52979934+matthewstevenson88@users.noreply.github.com>
Date: Sun, 7 May 2023 21:17:29 -0700
Subject: [PATCH] [alts] Log host and target name on CheckCallHost failure.
 (#33028)

Having this logging will help debug a current failure.
---
 BUILD                                                      | 1 +
 .../security_connector/alts/alts_security_connector.cc     | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/BUILD b/BUILD
index bc65aadd4fc..b0b29f7e9b7 100644
--- a/BUILD
+++ b/BUILD
@@ -3156,6 +3156,7 @@ grpc_cc_library(
     external_deps = [
         "absl/status",
         "absl/strings",
+        "absl/strings:str_format",
         "absl/types:optional",
     ],
     language = "c++",
diff --git a/src/core/lib/security/security_connector/alts/alts_security_connector.cc b/src/core/lib/security/security_connector/alts/alts_security_connector.cc
index 159e3c9c967..f5fbde2842b 100644
--- a/src/core/lib/security/security_connector/alts/alts_security_connector.cc
+++ b/src/core/lib/security/security_connector/alts/alts_security_connector.cc
@@ -23,9 +23,11 @@
 #include <string.h>
 
 #include <algorithm>
+#include <initializer_list>
 #include <utility>
 
 #include "absl/status/status.h"
+#include "absl/strings/str_format.h"
 #include "absl/strings/string_view.h"
 #include "absl/types/optional.h"
 
@@ -132,8 +134,9 @@ class grpc_alts_channel_security_connector final
   grpc_core::ArenaPromise<absl::Status> CheckCallHost(
       absl::string_view host, grpc_auth_context*) override {
     if (host.empty() || host != target_name_) {
-      return grpc_core::Immediate(absl::UnauthenticatedError(
-          "ALTS call host does not match target name"));
+      return grpc_core::Immediate(absl::UnauthenticatedError(absl::StrFormat(
+          "ALTS call host [%s] does not match target name [%s].", host,
+          target_name_)));
     }
     return grpc_core::ImmediateOkStatus();
   }