Fix tcp_client memory leak and add test for it

src/core/lib/iomgr/tcp_client_posix.cc

@@ -357,6 +357,7 @@ static void tcp_connect(grpc_closure* closure, grpc_endpoint** ep,
   *ep = nullptr;
   if ((error = grpc_tcp_client_prepare_fd(channel_args, addr, &mapped_addr,
                                           &fd)) != GRPC_ERROR_NONE) {
+    grpc_slice_allocator_destroy(slice_allocator);
     grpc_core::ExecCtx::Run(DEBUG_LOCATION, closure, error);
     return;
   }

test/core/iomgr/tcp_client_posix_test.cc

@@ -78,6 +78,7 @@ static void must_fail(void* /*arg*/, grpc_error_handle error) {
 }
 
 void test_succeeds(void) {
+  gpr_log(GPR_ERROR, "---- starting test_succeeds() ----");
   grpc_resolved_address resolved_addr;
   struct sockaddr_in* addr =
       reinterpret_cast<struct sockaddr_in*>(resolved_addr.addr);
@@ -87,8 +88,6 @@ void test_succeeds(void) {
   grpc_closure done;
   grpc_core::ExecCtx exec_ctx;
 
-  gpr_log(GPR_DEBUG, "test_succeeds");
-
   memset(&resolved_addr, 0, sizeof(resolved_addr));
   resolved_addr.len = static_cast<socklen_t>(sizeof(struct sockaddr_in));
   addr->sin_family = AF_INET;
@@ -135,9 +134,11 @@ void test_succeeds(void) {
   }
 
   gpr_mu_unlock(g_mu);
+  gpr_log(GPR_ERROR, "---- finished test_succeeds() ----");
 }
 
 void test_fails(void) {
+  gpr_log(GPR_ERROR, "---- starting test_fails() ----");
   grpc_resolved_address resolved_addr;
   struct sockaddr_in* addr =
       reinterpret_cast<struct sockaddr_in*>(resolved_addr.addr);
@@ -145,8 +146,6 @@ void test_fails(void) {
   grpc_closure done;
   grpc_core::ExecCtx exec_ctx;
 
-  gpr_log(GPR_DEBUG, "test_fails");
-
   memset(&resolved_addr, 0, sizeof(resolved_addr));
   resolved_addr.len = static_cast<socklen_t>(sizeof(struct sockaddr_in));
   addr->sin_family = AF_INET;
@@ -184,6 +183,43 @@ void test_fails(void) {
   }
 
   gpr_mu_unlock(g_mu);
+  gpr_log(GPR_ERROR, "---- finished test_fails() ----");
+}
+
+void test_fails_bad_addr_no_leak(void) {
+  gpr_log(GPR_ERROR, "---- starting test_fails_bad_addr_no_leak() ----");
+  grpc_resolved_address resolved_addr;
+  struct sockaddr_in* addr =
+      reinterpret_cast<struct sockaddr_in*>(resolved_addr.addr);
+  int connections_complete_before;
+  grpc_closure done;
+  grpc_core::ExecCtx exec_ctx;
+  memset(&resolved_addr, 0, sizeof(resolved_addr));
+  resolved_addr.len = static_cast<socklen_t>(sizeof(struct sockaddr_in));
+  // force `grpc_tcp_client_prepare_fd` to fail. contrived, but effective.
+  addr->sin_family = AF_BLUETOOTH;
+  gpr_mu_lock(g_mu);
+  connections_complete_before = g_connections_complete;
+  gpr_mu_unlock(g_mu);
+  // connect to an invalid address.
+  GRPC_CLOSURE_INIT(&done, must_fail, nullptr, grpc_schedule_on_exec_ctx);
+  grpc_tcp_client_connect(
+      &done, &g_connecting, grpc_slice_allocator_create_unlimited(),
+      g_pollset_set, nullptr, &resolved_addr, GRPC_MILLIS_INF_FUTURE);
+  gpr_mu_lock(g_mu);
+  while (g_connections_complete == connections_complete_before) {
+    grpc_pollset_worker* worker = nullptr;
+    GPR_ASSERT(GRPC_LOG_IF_ERROR(
+        "pollset_work",
+        grpc_pollset_work(g_pollset, &worker,
+                          grpc_timespec_to_millis_round_up(
+                              grpc_timeout_seconds_to_deadline(5)))));
+    gpr_mu_unlock(g_mu);
+    grpc_core::ExecCtx::Get()->Flush();
+    gpr_mu_lock(g_mu);
+  }
+  gpr_mu_unlock(g_mu);
+  gpr_log(GPR_ERROR, "---- finished test_fails_bad_addr_no_leak() ----");
 }
 
 static void destroy_pollset(void* p, grpc_error_handle /*error*/) {
@@ -203,8 +239,8 @@ int main(int argc, char** argv) {
     grpc_pollset_set_add_pollset(g_pollset_set, g_pollset);
 
     test_succeeds();
-    gpr_log(GPR_ERROR, "End of first test");
     test_fails();
+    test_fails_bad_addr_no_leak();
     grpc_pollset_set_destroy(g_pollset_set);
     GRPC_CLOSURE_INIT(&destroyed, destroy_pollset, g_pollset,
                       grpc_schedule_on_exec_ctx);