fix race when initializing context in lokinet main.

when we configure but fail to start up, we can hit a case when we
have a context that is configured but not setup or running. when we
try to sigterm/sigint we get stuck and cannot exit as the
llarp::Context shared_ptr global is nullptr but dangles elsewhere.

we make it so that we fufill a promose if we fully configure and setup
successfully right before running the event loop main for it. this
makes it so we bail if setup was not completed and exit our process.

daemon/lokinet.cpp

@@ -1,4 +1,5 @@
 #include <chrono>
+#include <exception>
 #include <llarp/config/config.hpp>  // for ensure_config
 #include <llarp/constants/version.hpp>
 #include <llarp.hpp>
@@ -7,6 +8,9 @@
 #include <llarp/util/fs.hpp>
 #include <llarp/util/str.hpp>
 
+#include <llarp/router/abstractrouter.hpp>
+#include <memory>
+
 #ifdef _WIN32
 #include <llarp/win32/service_manager.hpp>
 #include <dbghelp.h>
@@ -62,7 +66,10 @@ namespace
   void
   handle_signal(int sig);
   static void
-  run_main_context(std::optional<fs::path> confFile, const llarp::RuntimeOptions opts);
+  run_main_context(
+      std::optional<fs::path> confFile,
+      const llarp::RuntimeOptions opts,
+      std::promise<std::shared_ptr<llarp::Context>>& startup);
 
   // variable declarations
   static auto logcat = llarp::log::Cat("main");
@@ -499,7 +506,20 @@ namespace
     SetUnhandledExceptionFilter(&GenerateDump);
 #endif
 
-    std::thread main_thread{[configFile, opts] { run_main_context(configFile, opts); }};
+    std::promise<std::shared_ptr<llarp::Context>> startup;
+
+    std::thread main_thread{
+        [configFile, opts, &startup] { run_main_context(configFile, opts, startup); }};
+    try
+    {
+      auto ftr = startup.get_future();
+      ctx = ftr.get();
+    }
+    catch (std::exception& ex)
+    {
+      oxen::log::error(logcat, "startup fail: {}", ex.what());
+      return 1;
+    }
     auto ftr = exit_code.get_future();
 
     do
@@ -567,7 +587,10 @@ namespace
 
   // this sets up, configures and runs the main context
   static void
-  run_main_context(std::optional<fs::path> confFile, const llarp::RuntimeOptions opts)
+  run_main_context(
+      std::optional<fs::path> confFile,
+      const llarp::RuntimeOptions opts,
+      std::promise<std::shared_ptr<llarp::Context>>& startup)
   {
     llarp::LogInfo(fmt::format("starting up {} {}", llarp::VERSION_FULL, llarp::RELEASE_MOTTO));
     try
@@ -586,14 +609,15 @@ namespace
       {
         llarp::LogError("failed to parse configuration");
         exit_code.set_value(1);
+        startup.set_value(nullptr);
         return;
       }
 
       // change cwd to dataDir to support relative paths in config
       fs::current_path(conf->router.m_dataDir);
 
-      ctx = std::make_shared<llarp::Context>();
-      ctx->Configure(std::move(conf));
+      auto _ctx = std::make_shared<llarp::Context>();
+      _ctx->Configure(std::move(conf));
 
       signal(SIGINT, handle_signal);
       signal(SIGTERM, handle_signal);
@@ -605,23 +629,23 @@ namespace
 
       try
       {
-        ctx->Setup(opts);
+        _ctx->Setup(opts);
       }
       catch (llarp::util::bind_socket_error& ex)
       {
         llarp::LogError(fmt::format("{}, is lokinet already running? 🤔", ex.what()));
-        exit_code.set_value(1);
+        startup.set_exception(std::current_exception());
         return;
       }
       catch (std::exception& ex)
       {
         llarp::LogError(fmt::format("failed to start up lokinet: {}", ex.what()));
-        exit_code.set_value(1);
+        startup.set_exception(std::current_exception());
         return;
       }
       llarp::util::SetThreadName("llarp-mainloop");
-
-      auto result = ctx->Run(opts);
+      startup.set_value(_ctx);
+      auto result = _ctx->Run(opts);
       exit_code.set_value(result);
     }
     catch (std::exception& e)

llarp/context.cpp

@@ -185,7 +185,7 @@ namespace llarp
   void
   Context::SigINT()
   {
-    if (router)
+    if (router and router->IsRunning())
     {
       llarp::log::debug(logcat, "Handling SIGINT");
       /// async stop router on sigint