feat: add support for session bus connection at custom address (#273)

* Add methods to initiate custom session bus connection

The new function helper `createSessionBusConnectionWithAddress` allows to create connection to session bus with custom address.

Signed-off-by: Alexander Livenets <a.livenets@gmail.com>

* feat: add support for session bus connection at custom address

Co-authored-by: Stanislav Angelovic <stanislav.angelovic@siemens.com>

src/Connection.cpp

@@ -60,6 +60,11 @@ Connection::Connection(std::unique_ptr<ISdBus>&& interface, session_bus_t)
 {
 }
 
+Connection::Connection(std::unique_ptr<ISdBus>&& interface, custom_session_bus_t, const std::string& address)
+        : Connection(std::move(interface), [&](sd_bus** bus) { return iface_->sd_bus_open_user_with_address(bus, address.c_str()); })
+{
+}
+
 Connection::Connection(std::unique_ptr<ISdBus>&& interface, remote_system_bus_t, const std::string& host)
     : Connection(std::move(interface), [this, &host](sd_bus** bus){ return iface_->sd_bus_open_system_remote(bus, host.c_str()); })
 {
@@ -572,6 +577,8 @@ std::unique_ptr<sdbus::internal::IConnection> createConnection()
 
 namespace sdbus {
 
+using internal::Connection;
+
 std::unique_ptr<sdbus::IConnection> createConnection()
 {
     return createSystemBusConnection();
@@ -585,8 +592,7 @@ std::unique_ptr<sdbus::IConnection> createConnection(const std::string& name)
 std::unique_ptr<sdbus::IConnection> createDefaultBusConnection()
 {
     auto interface = std::make_unique<sdbus::internal::SdBus>();
-    constexpr sdbus::internal::Connection::default_bus_t default_bus;
-    return std::make_unique<sdbus::internal::Connection>(std::move(interface), default_bus);
+    return std::make_unique<sdbus::internal::Connection>(std::move(interface), Connection::default_bus);
 }
 
 std::unique_ptr<sdbus::IConnection> createDefaultBusConnection(const std::string& name)
@@ -599,8 +605,7 @@ std::unique_ptr<sdbus::IConnection> createDefaultBusConnection(const std::string
 std::unique_ptr<sdbus::IConnection> createSystemBusConnection()
 {
     auto interface = std::make_unique<sdbus::internal::SdBus>();
-    constexpr sdbus::internal::Connection::system_bus_t system_bus;
-    return std::make_unique<sdbus::internal::Connection>(std::move(interface), system_bus);
+    return std::make_unique<sdbus::internal::Connection>(std::move(interface), Connection::system_bus);
 }
 
 std::unique_ptr<sdbus::IConnection> createSystemBusConnection(const std::string& name)
@@ -613,8 +618,7 @@ std::unique_ptr<sdbus::IConnection> createSystemBusConnection(const std::string&
 std::unique_ptr<sdbus::IConnection> createSessionBusConnection()
 {
     auto interface = std::make_unique<sdbus::internal::SdBus>();
-    constexpr sdbus::internal::Connection::session_bus_t session_bus;
-    return std::make_unique<sdbus::internal::Connection>(std::move(interface), session_bus);
+    return std::make_unique<sdbus::internal::Connection>(std::move(interface), Connection::session_bus);
 }
 
 std::unique_ptr<sdbus::IConnection> createSessionBusConnection(const std::string& name)
@@ -624,11 +628,17 @@ std::unique_ptr<sdbus::IConnection> createSessionBusConnection(const std::string
     return conn;
 }
 
+std::unique_ptr<sdbus::IConnection> createSessionBusConnectionWithAddress(const std::string &address)
+{
+    auto interface = std::make_unique<sdbus::internal::SdBus>();
+    assert(interface != nullptr);
+    return std::make_unique<sdbus::internal::Connection>(std::move(interface), Connection::custom_session_bus, address);
+}
+
 std::unique_ptr<sdbus::IConnection> createRemoteSystemBusConnection(const std::string& host)
 {
     auto interface = std::make_unique<sdbus::internal::SdBus>();
-    constexpr sdbus::internal::Connection::remote_system_bus_t remote_system_bus;
-    return std::make_unique<sdbus::internal::Connection>(std::move(interface), remote_system_bus, host);
+    return std::make_unique<sdbus::internal::Connection>(std::move(interface), Connection::remote_system_bus, host);
 }
 
 } // namespace sdbus

src/Connection.h

@@ -48,13 +48,20 @@ namespace sdbus::internal {
     public:
         // Bus type tags
         struct default_bus_t{};
+        inline static constexpr default_bus_t default_bus{};
         struct system_bus_t{};
+        inline static constexpr system_bus_t system_bus{};
         struct session_bus_t{};
+        inline static constexpr session_bus_t session_bus{};
+        struct custom_session_bus_t{};
+        inline static constexpr custom_session_bus_t custom_session_bus{};
         struct remote_system_bus_t{};
+        inline static constexpr remote_system_bus_t remote_system_bus{};
 
         Connection(std::unique_ptr<ISdBus>&& interface, default_bus_t);
         Connection(std::unique_ptr<ISdBus>&& interface, system_bus_t);
         Connection(std::unique_ptr<ISdBus>&& interface, session_bus_t);
+        Connection(std::unique_ptr<ISdBus>&& interface, custom_session_bus_t, const std::string& address);
         Connection(std::unique_ptr<ISdBus>&& interface, remote_system_bus_t, const std::string& host);
         ~Connection() override;
 

src/ISdBus.h

@@ -67,8 +67,9 @@ namespace sdbus::internal {
         virtual int sd_bus_emit_interfaces_removed_strv(sd_bus *bus, const char *path, char **interfaces) = 0;
 
         virtual int sd_bus_open(sd_bus **ret) = 0;
-        virtual int sd_bus_open_user(sd_bus **ret) = 0;
         virtual int sd_bus_open_system(sd_bus **ret) = 0;
+        virtual int sd_bus_open_user(sd_bus **ret) = 0;
+        virtual int sd_bus_open_user_with_address(sd_bus **ret, const char* address) = 0;
         virtual int sd_bus_open_system_remote(sd_bus **ret, const char* host) = 0;
         virtual int sd_bus_request_name(sd_bus *bus, const char *name, uint64_t flags) = 0;
         virtual int sd_bus_release_name(sd_bus *bus, const char *name) = 0;

src/SdBus.cpp

@@ -166,14 +166,46 @@ int SdBus::sd_bus_open(sd_bus **ret)
     return ::sd_bus_open(ret);
 }
 
+int SdBus::sd_bus_open_system(sd_bus **ret)
+{
+    return ::sd_bus_open_system(ret);
+}
+
 int SdBus::sd_bus_open_user(sd_bus **ret)
 {
     return ::sd_bus_open_user(ret);
 }
 
-int SdBus::sd_bus_open_system(sd_bus **ret)
+int SdBus::sd_bus_open_user_with_address(sd_bus **ret, const char* address)
 {
-    return ::sd_bus_open_system(ret);
+    sd_bus* bus = nullptr;
+
+    int r = sd_bus_new(&bus);
+    if (r < 0)
+        return r;
+
+    r = sd_bus_set_address(bus, address);
+    if (r < 0)
+        return r;
+
+    r = sd_bus_set_bus_client(bus, true);
+    if (r < 0)
+        return r;
+
+    // Copying behavior from
+    // https://github.com/systemd/systemd/blob/fee6441601c979165ebcbb35472036439f8dad5f/src/libsystemd/sd-bus/sd-bus.c#L1381
+    // Here, we make the bus as trusted
+    r = sd_bus_set_trusted(bus, true);
+    if (r < 0)
+        return r;
+
+    r = sd_bus_start(bus);
+    if (r < 0)
+        return r;
+
+    *ret = bus;
+
+    return 0;
 }
 
 int SdBus::sd_bus_open_system_remote(sd_bus **ret, const char *host)

src/SdBus.h

@@ -59,8 +59,9 @@ public:
     virtual int sd_bus_emit_interfaces_removed_strv(sd_bus *bus, const char *path, char **interfaces) override;
 
     virtual int sd_bus_open(sd_bus **ret) override;
-    virtual int sd_bus_open_user(sd_bus **ret) override;
     virtual int sd_bus_open_system(sd_bus **ret) override;
+    virtual int sd_bus_open_user(sd_bus **ret) override;
+    virtual int sd_bus_open_user_with_address(sd_bus **ret, const char* address) override;
     virtual int sd_bus_open_system_remote(sd_bus **ret, const char* hsot) override;
     virtual int sd_bus_request_name(sd_bus *bus, const char *name, uint64_t flags) override;
     virtual int sd_bus_release_name(sd_bus *bus, const char *name) override;