Fix issue with never-ending install retries

As backend sends empty director targets in some unexpected situations,
we've implemented a client-side mitigation in
02deeb5.

One unwanted side-effect is that after a failed installation, we'll keep
taking into account the targets containing the new version, hence
retrying installations in a loop until the backend asks to install
something new.

Second fix is to drop director targets after installation end, until
we've come to an agreement on a proper solution on both sides.

Signed-off-by: Laurent Bonnans <laurent.bonnans@here.com>

src/libaktualizr/primary/sotauptaneclient.cc

@@ -163,6 +163,7 @@ void SotaUptaneClient::finalizeAfterReboot() {
 
       computeDeviceInstallationResult(nullptr, correlation_id);
       putManifestSimple();
+      director_repo.dropLatest(*storage);  // fix for OTA-2587, listen to backend again after end of install
     } else {
       // nothing found on primary
       LOG_ERROR << "Expected reboot after update on primary but no update found";
@@ -828,6 +829,10 @@ result::Install SotaUptaneClient::uptaneInstall(const std::vector<Uptane::Target
   computeDeviceInstallationResult(&result.dev_report, correlation_id);
   sendEvent<event::AllInstallsComplete>(result);
 
+  if (result.dev_report.result_code != data::ResultCode::Numeric::kNeedCompletion) {
+    director_repo.dropLatest(*storage);  // fix for OTA-2587, listen to backend again after end of install
+  }
+
   return result;
 }
 

src/libaktualizr/uptane/directorrepository.cc

@@ -150,4 +150,9 @@ bool DirectorRepository::updateMeta(INvStorage& storage, Fetcher& fetcher) {
   return true;
 }
 
+void DirectorRepository::dropLatest(INvStorage& storage) {
+  storage.clearNonRootMeta(RepositoryType::Director());
+  latest_targets.clear();
+}
+
 }  // namespace Uptane

src/libaktualizr/uptane/directorrepository.h

@@ -24,6 +24,7 @@ class DirectorRepository : public RepositoryCommon {
   // a non-empty list.
   bool usePreviousTargets() const { return !targets.targets.empty() && latest_targets.targets.empty(); }
   bool checkMetaOffline(INvStorage& storage);
+  void dropLatest(INvStorage& storage);
 
   Exception getLastException() const { return last_exception; }
   bool updateMeta(INvStorage& storage, Fetcher& fetcher);

src/libaktualizr/uptane/tuf.h

@@ -432,6 +432,12 @@ class Targets : public MetaWithKeys {
     return version_ == rhs.version() && expiry_ == rhs.expiry() && targets == rhs.targets;
   }
   const std::string &correlation_id() const { return correlation_id_; }
+  void clear() {
+    targets.clear();
+    delegated_role_names_.clear();
+    paths_for_role_.clear();
+    terminating_role_.clear();
+  }
 
   std::vector<Uptane::Target> targets;
   std::vector<std::string> delegated_role_names_;