Add support for opening a connection to a remote system bus using ssh (#77)

include/sdbus-c++/IConnection.h

@@ -243,6 +243,15 @@ namespace sdbus {
      */
     std::unique_ptr<sdbus::IConnection> createSessionBusConnection(const std::string& name);
 
+    /*!
+     * @brief Creates/opens D-Bus system connection on a remote host using ssh
+     *
+     * @param[in] host Name of the host to connect
+     * @return Connection instance
+     *
+     * @throws sdbus::Error in case of failure
+     */
+    std::unique_ptr<sdbus::IConnection> createRemoteSystemBusConnection(const std::string& host);
 }
 
 #endif /* SDBUS_CXX_ICONNECTION_H_ */

src/Connection.cpp

@@ -64,6 +64,21 @@ Connection::Connection(Connection::BusType type, std::unique_ptr<ISdBus>&& inter
     loopExitFd_ = createProcessingLoopExitDescriptor();
 }
 
+Connection::Connection(const std::string& host, std::unique_ptr<ISdBus> &&interface)
+    : iface_(std::move(interface))
+    , busType_(BusType::eRemoteSystem)
+    , host_(host)
+{
+    assert(iface_ != nullptr);
+
+    auto bus = openBus(busType_);
+    bus_.reset(bus);
+
+    finishHandshake(bus);
+
+    loopExitFd_ = createProcessingLoopExitDescriptor();
+}
+
 Connection::~Connection()
 {
     leaveProcessingLoop();
@@ -294,6 +309,8 @@ sd_bus* Connection::openBus(Connection::BusType type)
         r = iface_->sd_bus_open_system(&bus);
     else if (type == BusType::eSession)
         r = iface_->sd_bus_open_user(&bus);
+    else if (type == BusType::eRemoteSystem)
+        r = iface_->sd_bus_open_system_remote(&bus, host_.c_str());
     else
         assert(false);
 
@@ -449,4 +466,12 @@ std::unique_ptr<sdbus::IConnection> createSessionBusConnection(const std::string
     return conn;
 }
 
+std::unique_ptr<sdbus::IConnection> createRemoteSystemBusConnection(const std::string& host)
+{
+    auto interface = std::make_unique<sdbus::internal::SdBus>();
+    assert(interface != nullptr);
+    return std::make_unique<sdbus::internal::Connection>( host
+                                                        , std::move(interface));
+}
+
 }

src/Connection.h

@@ -46,10 +46,12 @@ namespace sdbus { namespace internal {
         enum class BusType
         {
             eSystem,
-            eSession
+            eSession,
+            eRemoteSystem,
         };
 
         Connection(BusType type, std::unique_ptr<ISdBus>&& interface);
+        Connection(const std::string& host, std::unique_ptr<ISdBus>&& interface);
         ~Connection() override;
 
         void requestName(const std::string& name) override;
@@ -122,6 +124,7 @@ namespace sdbus { namespace internal {
 
         std::thread asyncLoopThread_;
         int loopExitFd_{-1};
+        std::string host_;
     };
 
 }}

src/ISdBus.h

@@ -67,6 +67,7 @@ namespace sdbus { namespace internal {
 
         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_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;
         virtual int sd_bus_add_object_vtable(sd_bus *bus, sd_bus_slot **slot, const char *path, const char *interface, const sd_bus_vtable *vtable, void *userdata) = 0;

src/SdBus.cpp

@@ -164,6 +164,11 @@ int SdBus::sd_bus_open_system(sd_bus **ret)
     return ::sd_bus_open_system(ret);
 }
 
+int SdBus::sd_bus_open_system_remote(sd_bus **ret, const char *host)
+{
+    return ::sd_bus_open_system_remote(ret, host);
+}
+
 int SdBus::sd_bus_request_name(sd_bus *bus, const char *name, uint64_t flags)
 {
     std::unique_lock<std::recursive_mutex> lock(sdbusMutex_);

src/SdBus.h

@@ -59,6 +59,7 @@ public:
 
     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_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;
     virtual int sd_bus_add_object_vtable(sd_bus *bus, sd_bus_slot **slot, const char *path, const char *interface, const sd_bus_vtable *vtable, void *userdata) override;