commit 3ee23aba89989fa6174965cbd6e52daf7f11c0d8
author Cody Schuffelen <schuffelen@google.com> Tue Jan 15 17:22:35 2019 -0800
committer Cody Schuffelen <schuffelen@google.com> Thu Jan 17 16:14:39 2019 -0800
tree 89b2cff87dc11b01972b08dfda472328cdad8d21
parent 834fbf69ce89846c500d29d71273477bac668160

Fail gracefully in kernels missing vsock support.

socket_vsock_proxy will now wait forever in the guest on encountering an
"unrecoverable" errno. This is to prevent churn from being restarted by
init.vsoc.rc.

In the host, it will close the TCP connection if it fails to make the
corresponding vsock connection.

Bug: 121166534
Test: Checked for crash logs in bugreport with vsock on/off.
Change-Id: Ia81c0943c4082d8851140e647abaaf5fde5915d5

common/frontend/socket_vsock_proxy/Android.bp

diff --git a/common/frontend/socket_vsock_proxy/Android.bp b/common/frontend/socket_vsock_proxy/Android.bp
index a0bc46f..0a2f572 100644
--- a/common/frontend/socket_vsock_proxy/Android.bp
+++ b/common/frontend/socket_vsock_proxy/Android.bp
@@ -19,6 +19,7 @@
         "main.cpp",
     ],
     shared_libs: [
+        "cuttlefish_auto_resources",
         "libbase",
         "libcuttlefish_fs",
         "libcuttlefish_utils",

common/frontend/socket_vsock_proxy/main.cpp

diff --git a/common/frontend/socket_vsock_proxy/main.cpp b/common/frontend/socket_vsock_proxy/main.cpp
index 50503ad..a47915b 100644
--- a/common/frontend/socket_vsock_proxy/main.cpp
+++ b/common/frontend/socket_vsock_proxy/main.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <set>
 #include <thread>
 #include <glog/logging.h>
 #include <gflags/gflags.h>
@@ -147,10 +148,11 @@
     auto client_socket = cvd::SharedFD::Accept(*server);
     CHECK(client_socket->IsOpen()) << "error creating client socket";
     LOG(INFO) << "client socket accepted";
-    auto vsock_socket = cvd::SharedFD::VsockClient(FLAGS_vsock_guest_cid,
-                                                   FLAGS_guest_port,
-                                                   SOCK_STREAM);
-    CHECK(vsock_socket->IsOpen()) << "error connecting over vsock";
+    cvd::SharedFD vsock_socket = cvd::SharedFD::VsockClient(
+        FLAGS_vsock_guest_cid, FLAGS_guest_port, SOCK_STREAM);
+    if (!vsock_socket->IsOpen()) {
+      continue;
+    }
     auto thread = std::thread(HandleConnection, std::move(vsock_socket),
                               std::move(client_socket));
     thread.detach();
@@ -170,10 +172,28 @@
   }
 }
 
+bool socketErrorIsRecoverable(int error) {
+  std::set<int> unrecoverable{EACCES, EAFNOSUPPORT, EINVAL, EPROTONOSUPPORT};
+  return unrecoverable.find(error) == unrecoverable.end();
+}
+
+[[noreturn]] static void SleepForever() {
+  while (true) {
+    sleep(std::numeric_limits<unsigned int>::max());
+  }
+}
+
 [[noreturn]] void guest() {
   LOG(INFO) << "Starting guest mainloop";
   LOG(INFO) << "starting server on " << FLAGS_guest_port;
-  auto vsock = cvd::SharedFD::VsockServer(FLAGS_guest_port, SOCK_STREAM);
+  cvd::SharedFD vsock;
+  do {
+    vsock = cvd::SharedFD::VsockServer(FLAGS_guest_port, SOCK_STREAM);
+    if (!vsock->IsOpen() && !socketErrorIsRecoverable(vsock->GetErrno())) {
+      LOG(ERROR) << "Could not open vsock socket: " << vsock->StrError();
+      SleepForever();
+    }
+  } while (!vsock->IsOpen());
   CHECK(vsock->IsOpen()) << "Could not start server on " << FLAGS_guest_port;
   while (true) {
     LOG(INFO) << "waiting for vsock connection";