From a5faa56a62399725859681d14fcf98e4f95000ef Mon Sep 17 00:00:00 2001
From: Zhanglong Xia <zhanglongxia@google.com>
Date: Mon, 18 Nov 2024 14:15:03 +0800
Subject: [PATCH] check whether the network interface exists before using it

Some build targets of the cuttlefish project don't have the
ethernet interface. This CL checks whether the network interface
exists before setting it as Thread simulation local interface.

Bug: b/378777255
Test: acloudw create --branch git_main --build-id P85047583 --build-target cf_x86_64_auto-trunk_staging-userdebug
Change-Id: Ifb1e316f59fac7babf34a7c290d5234853de8653
---
 threadnetwork/aidl/default/main.cpp | 39 ++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/threadnetwork/aidl/default/main.cpp b/threadnetwork/aidl/default/main.cpp
index 6514184f77..1df455eb0f 100644
--- a/threadnetwork/aidl/default/main.cpp
+++ b/threadnetwork/aidl/default/main.cpp
@@ -18,11 +18,11 @@
 #include <android-base/logging.h>
 #include <android/binder_manager.h>
 #include <android/binder_process.h>
-#include <netinet/in.h>
-#include <net/if.h>
-#include <utils/Log.h>
 #include <cutils/properties.h>
+#include <net/if.h>
+#include <netinet/in.h>
 #include <sys/stat.h>
+#include <utils/Log.h>
 
 #include "service.hpp"
 #include "thread_chip.hpp"
@@ -30,13 +30,19 @@
 using aidl::android::hardware::threadnetwork::IThreadChip;
 using aidl::android::hardware::threadnetwork::ThreadChip;
 
-#define THREADNETWORK_COPROCESSOR_SIMULATION_PATH "/apex/com.android.hardware.threadnetwork/bin/ot-rcp"
+#define THREADNETWORK_COPROCESSOR_SIMULATION_PATH \
+    "/apex/com.android.hardware.threadnetwork/bin/ot-rcp"
 
 namespace {
+
+bool isInterfaceExists(const char* interfaceName) {
+    return if_nametoindex(interfaceName) != 0;
+}
+
 void addThreadChip(int id, const char* url) {
     binder_status_t status;
     const std::string serviceName(std::string() + IThreadChip::descriptor + "/chip" +
-            std::to_string(id));
+                                  std::to_string(id));
 
     ALOGI("ServiceName: %s, Url: %s", serviceName.c_str(), url);
 
@@ -50,19 +56,24 @@ void addThreadChip(int id, const char* url) {
 
 void addSimulatedThreadChip() {
     char local_interface[PROP_VALUE_MAX];
-
-    CHECK_GT(property_get("persist.vendor.otsim.local_interface",
-                local_interface, "eth1"), 0);
-
     int node_id = property_get_int32("ro.boot.openthread_node_id", 0);
-    CHECK_GT(node_id,0);
 
-    std::string url = std::string("spinel+hdlc+forkpty://" \
-            THREADNETWORK_COPROCESSOR_SIMULATION_PATH "?forkpty-arg=-L") \
-                      + local_interface + "&forkpty-arg=" + std::to_string(node_id);
+    CHECK_GT(node_id, 0);
+
+    std::string url = std::string("spinel+hdlc+forkpty://" THREADNETWORK_COPROCESSOR_SIMULATION_PATH
+                                  "?forkpty-arg=") +
+                      std::to_string(node_id);
+
+    CHECK_GT(property_get("persist.vendor.otsim.local_interface", local_interface, "eth1"), 0);
+    if (isInterfaceExists(local_interface)) {
+        url += std::string("&forkpty-arg=-L") + local_interface;
+    } else {
+        ALOGI("Interface %s doesn't exist!", local_interface);
+    }
+
     addThreadChip(0, url.c_str());
 }
-}
+}  // namespace
 
 int main(int argc, char* argv[]) {
     aidl::android::hardware::threadnetwork::Service service;