Ground work for pluggable storage serializers

scripts/base/frameworks/storage/async.zeek

@@ -25,9 +25,8 @@ export {
 	## Returns: A record containing the status of the operation, and either an error
 	##          string on failure or a value on success. The value returned here will
 	##          be an ``opaque of BackendHandle``.
-	global open_backend: function(btype: Storage::Backend,
-	    options: Storage::BackendOptions, key_type: any, val_type: any)
-	    : Storage::OperationResult;
+	global open_backend: function(btype: Storage::Backend, options: Storage::BackendOptions,
+	    key_type: any, val_type: any): Storage::OperationResult;
 
 	## Closes an existing backend connection asynchronously. This method must be
 	## called via a :zeek:see:`when` condition or an error will be returned.

scripts/base/frameworks/storage/main.zeek

@@ -7,23 +7,26 @@ export {
 	## :zeek:see:`Storage::Async::open_backend` and
 	## :zeek:see:`Storage::Sync::open_backend`. Backend plugins can redef this record
 	## to add relevant fields to it.
-	type BackendOptions: record { };
+	type BackendOptions: record {
+		## The serializer used for converting Zeek data.
+		serializer: Storage::Serializer &default=Storage::JSON;
+	};
 
 	## Record for passing arguments to :zeek:see:`Storage::Async::put` and
 	## :zeek:see:`Storage::Sync::put`.
 	type PutArgs: record {
-		# The key to store the value under.
+		## The key to store the value under.
 		key: any;
 
-		# The value to store associated with the key.
+		## The value to store associated with the key.
 		value: any;
 
-		# Indicates whether this value should overwrite an existing entry for the
-		# key.
+		## Indicates whether this value should overwrite an existing entry for the
+		## key.
 		overwrite: bool &default=T;
 
-		# An interval of time until the entry is automatically removed from the
-		# backend.
+		## An interval of time until the entry is automatically removed from the
+		## backend.
 		expire_time: interval &default=0sec;
 	};
 }

scripts/base/frameworks/storage/sync.zeek

@@ -23,9 +23,8 @@ export {
 	## Returns: A record containing the status of the operation, and either an error
 	##          string on failure or a value on success. The value returned here will
 	##          be an ``opaque of BackendHandle``.
-	global open_backend: function(btype: Storage::Backend,
-	    options: Storage::BackendOptions, key_type: any, val_type: any)
-	    : Storage::OperationResult;
+	global open_backend: function(btype: Storage::Backend, options: Storage::BackendOptions,
+	    key_type: any, val_type: any): Storage::OperationResult;
 
 	## Closes an existing backend connection.
 	##

src/plugin/Component.cc

@@ -47,6 +47,8 @@ void Component::Describe(ODesc* d) const {
 
         case component::STORAGE_BACKEND: d->Add("Storage Backend"); break;
 
+        case component::STORAGE_SERIALIZER: d->Add("Storage Serializer"); break;
+
         default:
             reporter->InternalWarning("unknown component type in plugin::Component::Describe");
             d->Add("<unknown component type>");

src/plugin/Component.h

@@ -34,6 +34,7 @@ enum Type {
     EVENT_SERIALIZER,   /// A serializer for events, used by cluster backends.
     LOG_SERIALIZER,     /// A serializer for log batches, used by cluster backends.
     STORAGE_BACKEND,    /// A backend for the storage framework.
+    STORAGE_SERIALIZER, /// A serializer for the storage framework.
 };
 
 } // namespace component

src/storage/Backend.cc

@@ -66,7 +66,7 @@ void OpenResultCallback::Complete(OperationResult res) {
 }
 
 Backend::Backend(uint8_t modes, std::string_view tag_name) : modes(modes) {
-    tag = storage_mgr->GetComponentTag(std::string{tag_name});
+    tag = storage_mgr->BackendMgr().GetComponentTag(std::string{tag_name});
     tag_str = zeek::obj_desc_short(tag.AsVal().get());
 }
 
@@ -75,6 +75,15 @@ OperationResult Backend::Open(OpenResultCallback* cb, RecordValPtr options, Type
     val_type = std::move(vt);
     backend_options = options;
 
+    auto stype = options->GetField<EnumVal>("serializer");
+    zeek::Tag stag{stype};
+
+    auto s = storage_mgr->InstantiateSerializer(stag);
+    if ( ! s )
+        return {ReturnCode::INITIALIZATION_FAILED, s.error()};
+
+    serializer = std::move(s.value());
+
     auto ret = DoOpen(cb, std::move(options));
     if ( ! ret.value )
         ret.value = cb->Backend();

src/storage/Backend.h

@@ -5,6 +5,7 @@
 #include "zeek/OpaqueVal.h"
 #include "zeek/Tag.h"
 #include "zeek/Val.h"
+#include "zeek/storage/Serializer.h"
 
 namespace zeek::detail::trigger {
 class Trigger;
@@ -58,7 +59,7 @@ struct OperationResult {
 class ResultCallback {
 public:
     ResultCallback() = default;
-    ResultCallback(detail::trigger::TriggerPtr trigger, const void* assoc);
+    ResultCallback(zeek::detail::trigger::TriggerPtr trigger, const void* assoc);
     virtual ~ResultCallback() = default;
 
     /**
@@ -239,6 +240,7 @@ protected:
 
     zeek::Tag tag;
     std::string tag_str;
+    std::unique_ptr<Serializer> serializer;
 
 private:
     /**

src/storage/CMakeLists.txt

@@ -11,3 +11,4 @@ zeek_add_subdir_library(
     storage-sync.bif)
 
 add_subdirectory(backend)
+add_subdirectory(serializer)

src/storage/Component.cc

@@ -7,19 +7,34 @@
 
 namespace zeek::storage {
 
-Component::Component(const std::string& name, factory_callback arg_factory)
-    : plugin::Component(plugin::component::STORAGE_BACKEND, name, 0, storage_mgr->GetTagType()) {
+BackendComponent::BackendComponent(const std::string& name, factory_callback arg_factory)
+    : plugin::Component(plugin::component::STORAGE_BACKEND, name, 0, storage_mgr->BackendMgr().GetTagType()) {
     factory = arg_factory;
 }
 
-void Component::Initialize() {
+void BackendComponent::Initialize() {
     InitializeTag();
-    storage_mgr->RegisterComponent(this);
+    storage_mgr->BackendMgr().RegisterComponent(this);
 }
 
-void Component::DoDescribe(ODesc* d) const {
+void BackendComponent::DoDescribe(ODesc* d) const {
     d->Add("Storage::STORAGE_BACKEND_");
     d->Add(CanonicalName());
 }
 
+SerializerComponent::SerializerComponent(const std::string& name, factory_callback arg_factory)
+    : plugin::Component(plugin::component::STORAGE_SERIALIZER, name, 0, storage_mgr->SerializerMgr().GetTagType()) {
+    factory = arg_factory;
+}
+
+void SerializerComponent::Initialize() {
+    InitializeTag();
+    storage_mgr->SerializerMgr().RegisterComponent(this);
+}
+
+void SerializerComponent::DoDescribe(ODesc* d) const {
+    d->Add("Storage::STORAGE_SERIALIZER_");
+    d->Add(CanonicalName());
+}
+
 } // namespace zeek::storage

src/storage/Component.h

@@ -7,11 +7,12 @@
 namespace zeek::storage {
 
 class Backend;
+class Serializer;
 
 /**
  * Component description for plugins providing storage backends.
  */
-class Component : public plugin::Component {
+class BackendComponent : public plugin::Component {
 public:
     using factory_callback = IntrusivePtr<Backend> (*)();
 
@@ -27,12 +28,60 @@ public:
      * method inside the class that just allocates and returns a new
      * instance.
      */
-    Component(const std::string& name, factory_callback factory);
+    BackendComponent(const std::string& name, factory_callback factory);
 
     /**
      * Destructor.
      */
-    ~Component() override = default;
+    ~BackendComponent() override = default;
+
+    /**
+     * Initialization function. This function has to be called before any
+     * plugin component functionality is used; it is used to add the
+     * plugin component to the list of components and to initialize tags
+     */
+    void Initialize() override;
+
+    /**
+     * Returns the backend's factory function.
+     */
+    factory_callback Factory() const { return factory; }
+
+protected:
+    /**
+     * Overridden from plugin::Component.
+     */
+    void DoDescribe(ODesc* d) const override;
+
+private:
+    factory_callback factory;
+};
+
+/**
+ * Component description for plugins providing serialization for storage data..
+ */
+class SerializerComponent : public plugin::Component {
+public:
+    using factory_callback = std::unique_ptr<Serializer> (*)();
+
+    /**
+     * Constructor.
+     *
+     * @param name The name of the provided backend. This name is used
+     * across the system to identify the backend.
+     *
+     * @param factory A factory function to instantiate instances of the
+     * backend's class, which must be derived directly or indirectly from
+     * storage::Backend. This is typically a static \c Instantiate()
+     * method inside the class that just allocates and returns a new
+     * instance.
+     */
+    SerializerComponent(const std::string& name, factory_callback factory);
+
+    /**
+     * Destructor.
+     */
+    ~SerializerComponent() override = default;
 
     /**
      * Initialization function. This function has to be called before any

src/storage/Manager.cc

@@ -28,7 +28,9 @@ void detail::ExpirationTimer::Dispatch(double t, bool is_expire) {
     storage_mgr->StartExpirationTimer();
 }
 
-Manager::Manager() : plugin::ComponentManager<storage::Component>("Storage", "Backend") {}
+Manager::Manager()
+    : backend_mgr(plugin::ComponentManager<storage::BackendComponent>("Storage", "Backend")),
+      serializer_mgr(plugin::ComponentManager<storage::SerializerComponent>("Storage", "Serializer")) {}
 
 Manager::~Manager() {
     // TODO: should we shut down any existing backends? force-poll until all of their existing
@@ -48,24 +50,40 @@ void Manager::InitPostScript() {
     StartExpirationTimer();
 }
 
-zeek::expected<BackendPtr, std::string> Manager::Instantiate(const Tag& type) {
-    Component* c = Lookup(type);
-    if ( ! c ) {
+zeek::expected<BackendPtr, std::string> Manager::InstantiateBackend(const Tag& type) {
+    BackendComponent* c = backend_mgr.Lookup(type);
+    if ( ! c )
         return zeek::unexpected<std::string>(
-            util::fmt("Request to open unknown backend (%d:%d)", type.Type(), type.Subtype()));
-    }
+            util::fmt("Request to instantiate unknown backend type (%d:%d)", type.Type(), type.Subtype()));
 
-    if ( ! c->Factory() ) {
+    if ( ! c->Factory() )
         return zeek::unexpected<std::string>(
-            util::fmt("Factory invalid for backend %s", GetComponentName(type).c_str()));
-    }
+            util::fmt("Factory invalid for backend %s", backend_mgr.GetComponentName(type).c_str()));
 
-    BackendPtr bp = c->Factory()();
+    auto bp = c->Factory()();
 
-    if ( ! bp ) {
+    if ( ! bp )
         return zeek::unexpected<std::string>(
-            util::fmt("Failed to instantiate backend %s", GetComponentName(type).c_str()));
-    }
+            util::fmt("Failed to instantiate backend %s", backend_mgr.GetComponentName(type).c_str()));
+
+    return bp;
+}
+
+zeek::expected<std::unique_ptr<Serializer>, std::string> Manager::InstantiateSerializer(const Tag& type) {
+    SerializerComponent* c = serializer_mgr.Lookup(type);
+    if ( ! c )
+        return zeek::unexpected<std::string>(
+            util::fmt("Request to instantiate unknown serializer type (%d:%d)", type.Type(), type.Subtype()));
+
+    if ( ! c->Factory() )
+        return zeek::unexpected<std::string>(
+            util::fmt("Factory invalid for serializer %s", serializer_mgr.GetComponentName(type).c_str()));
+
+    auto bp = c->Factory()();
+
+    if ( ! bp )
+        return zeek::unexpected<std::string>(
+            util::fmt("Failed to instantiate serializer %s", serializer_mgr.GetComponentName(type).c_str()));
 
     return bp;
 }

src/storage/Manager.h

@@ -10,6 +10,7 @@
 #include "zeek/plugin/ComponentManager.h"
 #include "zeek/storage/Backend.h"
 #include "zeek/storage/Component.h"
+#include "zeek/storage/Serializer.h"
 
 namespace zeek::storage {
 
@@ -24,7 +25,7 @@ public:
 
 } // namespace detail
 
-class Manager final : public plugin::ComponentManager<Component> {
+class Manager final {
 public:
     Manager();
     ~Manager();
@@ -43,7 +44,16 @@ public:
      * @return A std::expected containing either a valid BackendPtr with the result of the
      * operation or a string containing an error message for failure.
      */
-    zeek::expected<BackendPtr, std::string> Instantiate(const Tag& type);
+    zeek::expected<BackendPtr, std::string> InstantiateBackend(const Tag& type);
+
+    /**
+     * Instantiates a new serializer object.
+     *
+     * @param type The tag for the type of backend being opened.
+     * @return A std::expected containing either a valid BackendPtr with the result of the
+     * operation or a string containing an error message for failure.
+     */
+    zeek::expected<std::unique_ptr<Serializer>, std::string> InstantiateSerializer(const Tag& type);
 
     /**
      * Opens a new storage backend.
@@ -82,6 +92,9 @@ public:
      */
     void Expire(double t);
 
+    plugin::ComponentManager<BackendComponent>& BackendMgr() { return backend_mgr; }
+    plugin::ComponentManager<SerializerComponent>& SerializerMgr() { return serializer_mgr; }
+
 protected:
     friend class storage::detail::ExpirationTimer;
     void RunExpireThread();
@@ -94,6 +107,9 @@ protected:
 private:
     std::vector<BackendPtr> backends;
     std::mutex backends_mtx;
+
+    plugin::ComponentManager<BackendComponent> backend_mgr;
+    plugin::ComponentManager<SerializerComponent> serializer_mgr;
 };
 
 } // namespace zeek::storage

src/storage/ReturnCode.cc

@@ -19,6 +19,8 @@ EnumValPtr ReturnCode::CONNECTION_FAILED;
 EnumValPtr ReturnCode::DISCONNECTION_FAILED;
 EnumValPtr ReturnCode::INITIALIZATION_FAILED;
 EnumValPtr ReturnCode::IN_PROGRESS;
+EnumValPtr ReturnCode::SERIALIZATION_FAILED;
+EnumValPtr ReturnCode::UNSERIALIZATION_FAILED;
 
 void ReturnCode::Initialize() {
     static const auto& return_code_type = zeek::id::find_type<zeek::EnumType>("Storage::ReturnCode");
@@ -61,6 +63,12 @@ void ReturnCode::Initialize() {
 
     tmp = return_code_type->Lookup("Storage::IN_PROGRESS");
     IN_PROGRESS = return_code_type->GetEnumVal(tmp);
+
+    tmp = return_code_type->Lookup("Storage::SERIALIZATION_FAILED");
+    SERIALIZATION_FAILED = return_code_type->GetEnumVal(tmp);
+
+    tmp = return_code_type->Lookup("Storage::UNSERIALIZATION_FAILED");
+    UNSERIALIZATION_FAILED = return_code_type->GetEnumVal(tmp);
 }
 
 void ReturnCode::Cleanup() {
@@ -77,6 +85,8 @@ void ReturnCode::Cleanup() {
     DISCONNECTION_FAILED.reset();
     INITIALIZATION_FAILED.reset();
     IN_PROGRESS.reset();
+    SERIALIZATION_FAILED.reset();
+    UNSERIALIZATION_FAILED.reset();
 }
 
 } // namespace zeek::storage

src/storage/ReturnCode.h

@@ -32,6 +32,8 @@ public:
     static EnumValPtr DISCONNECTION_FAILED;
     static EnumValPtr INITIALIZATION_FAILED;
     static EnumValPtr IN_PROGRESS;
+    static EnumValPtr SERIALIZATION_FAILED;
+    static EnumValPtr UNSERIALIZATION_FAILED;
 };
 
 } // namespace storage

src/storage/Serializer.h

@@ -0,0 +1,50 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+#pragma once
+
+#include "zeek/Span.h"
+#include "zeek/Val.h"
+
+namespace zeek::storage {
+
+namespace detail {
+using byte_buffer = std::vector<std::byte>;
+using byte_buffer_span = Span<const std::byte>;
+} // namespace detail
+
+/**
+ * Base class for a serializer used by storage backends.
+ */
+class Serializer {
+public:
+    virtual ~Serializer() = default;
+
+    /**
+     * Serializes Zeek Val data into another format.
+     *
+     * @param val The data to serialize.
+     *
+     * @return On success, a byte buffer containing the serialized data. std::nullopt will
+     *  be returned on failure.
+     */
+    virtual std::optional<detail::byte_buffer> Serialize(ValPtr val) = 0;
+
+    /**
+     * Unserializes a byte buffer into Zeek Val objects of a specific type.
+     *
+     * @param buf The byte data to unserialize.
+     * @param type The Zeek script-level type to unserialize the data into.
+     *
+     * @return A zeek::expected containing either the unserialized Val data on success, or
+     * a string containing an error message on failure.
+     */
+    virtual zeek::expected<ValPtr, std::string> Unserialize(detail::byte_buffer_span buf, TypePtr type) = 0;
+
+protected:
+    Serializer(std::string name) : name(std::move(name)) {}
+
+private:
+    std::string name;
+};
+
+} // namespace zeek::storage

src/storage/backend/redis/Plugin.cc

@@ -10,7 +10,7 @@ namespace zeek::storage::backend::redis {
 class Plugin : public plugin::Plugin {
 public:
     plugin::Configuration Configure() override {
-        AddComponent(new storage::Component("REDIS", backend::redis::Redis::Instantiate));
+        AddComponent(new storage::BackendComponent("REDIS", backend::redis::Redis::Instantiate));
 
         plugin::Configuration config;
         config.name = "Zeek::Storage_Backend_Redis";

src/storage/backend/sqlite/Plugin.cc

@@ -10,7 +10,7 @@ namespace zeek::storage::backend::sqlite {
 class Plugin : public plugin::Plugin {
 public:
     plugin::Configuration Configure() override {
-        AddComponent(new storage::Component("SQLITE", backend::sqlite::SQLite::Instantiate));
+        AddComponent(new storage::BackendComponent("SQLITE", backend::sqlite::SQLite::Instantiate));
 
         plugin::Configuration config;
         config.name = "Zeek::Storage_Backend_SQLite";

src/storage/storage-async.bif

@@ -80,9 +80,9 @@ function Storage::Async::__open_backend%(btype: Storage::Backend, options: any,
 		return nullptr;
 
 	auto btype_val = IntrusivePtr<EnumVal>{NewRef{}, btype->AsEnumVal()};
-	Tag tag{btype_val};
+	Tag btag{btype_val};
 
-	auto b = storage_mgr->Instantiate(tag);
+	auto b = storage_mgr->InstantiateBackend(btag);
 
 	if ( ! b.has_value() ) {
 		trigger->Cache(

src/storage/storage-sync.bif

@@ -31,9 +31,9 @@ module Storage::Sync;
 function Storage::Sync::__open_backend%(btype: Storage::Backend, options: any, key_type: any, val_type: any%): Storage::OperationResult
 	%{
 	auto btype_val = IntrusivePtr<EnumVal>{NewRef{}, btype->AsEnumVal()};
-	Tag tag{btype_val};
+	Tag btag{btype_val};
 
-	auto b = storage_mgr->Instantiate(tag);
+	auto b = storage_mgr->InstantiateBackend(btag);
 
 	if ( ! b.has_value() ) {
 		emit_builtin_error(b.error().c_str());

src/zeekygen/ScriptInfo.cc

@@ -324,6 +324,8 @@ void ScriptInfo::DoInitPostScript() {
     else if ( name == "base/frameworks/storage/main.zeek" ) {
         const auto& backend_id = zeek::detail::global_scope()->Find("Storage::Backend");
         types.push_back(new IdentifierInfo(backend_id, this));
+        const auto& serializer_id = zeek::detail::global_scope()->Find("Storage::Serializer");
+        types.push_back(new IdentifierInfo(serializer_id, this));
     }
 }