Add support for logging with VSOCK (#255)

For more information about VSOCK, see "man vsock"
( https://man7.org/linux/man-pages/man7/vsock.7.html ).

Makes it possible for processes in a virtual machine to log directly in
DLT running on host without setting up a network connection between
guest and host. It is also probably more efficient. Have not done any
performance measurements (not main reason for patch), but no forwarding
is required as when running DLT in a multi-node setup.

When building dlt-daemon for host, WITH_DLT_DAEMON_VSOCK_IPC should be
enabled for daemon to listen on incoming VSOCK requests. Local
communication method between applications and daemon is still determined
with DLT_IPC. When building for guest, WITH_DLT_LIB_VSOCK_IPC should be
enabled and DLT_IPC will be ignored, which will make libdlt open a VSOCK
socket to the deamon for logging messages.

VSOCK can be tested without a virtual machine. Since VMADDR_CID_HOST is
used by libdlt when connecting, see vsock man page, clients can be run
on host to test VSOCK communication.

Some modifications has been done to be able to handle logging through
FIFO pipe and socket in the same build of dlt-daemon:

- dlt_receiver_init/free_unix_socket() is renamed to
  dlt_receiver_init/free_global_buffer() and used for FIFO as well.
  Also fixes memory leak since dlt_receiver_free_unix_socket() was used
  regardless of whether DLT_USE_UNIX_SOCKET was defined or not.

- Pass type to dlt_receiver_init() instead of dlt_receiver_receive().
  And remove preprocessor conditionals for handling
  DLT_CONNECTION_APP_MSG in dlt_daemon_process_user_messages(). Also
  fixes wrong enum type being passed to dlt_receiver_receive() in
  dlt_client.c (DltClient::mode was used as a DltReceiverType enum but
  it is a DltClientMode enum).

- Add a flag to DltDaemonApplication to indicate whether file descriptor
  is "owned" by the DltDaemonApplication or not. When
  dlt_daemon_application_add() is called due to message received on a
  socket, fd is passed as an argument (app does not own fd). For FIFO,
  a per application FIFO is opened (app owns the fd). Also fixes so that
  user handle is reset for both application and all its contexts when
  resetting any. Prevents fd from being used by accident after it has
  been closed.

dlt_mkdir_recursive() is moved to src/daemon since it is only used in
the daemon. Minimizes use of DLT_USE_UNIX_SOCKET_IPC.

Other bugfixes:

- Call DLT_SEM_FREE() if setting socket to O_NONBLOCK fails in
  src/lib/dlt_user.c:dlt_initialize_socket_connection().

- Close socket if dlt_receiver_init() fails in
  src/lib/dlt_user.c:dlt_initialize_socket_connection().

Signed-off-by: Martin Ejdestig <martin.ejdestig@volvocars.com>

6 files changed, 213 insertions, 105 deletions

diff --git a/src/daemon/dlt-daemon.c b/src/daemon/dlt-daemon.c
index cd6e5d9..d4a5e90 100644
--- a/src/daemon/dlt-daemon.c
+++ b/src/daemon/dlt-daemon.c
@@ -50,6 +50,15 @@
 #   include <linux/stat.h>
 #endif
 
+#ifdef DLT_DAEMON_VSOCK_IPC_ENABLE
+#   ifdef linux
+#       include <linux/vm_sockets.h>
+#   endif
+#   ifdef __QNX__
+#       include <vm_sockets.h>
+#   endif
+#endif
+
 #include "dlt_types.h"
 #include "dlt-daemon.h"
 #include "dlt-daemon_cfg.h"
@@ -106,7 +115,7 @@ void usage()
     printf("  -h            Usage\n");
     printf("  -c filename   DLT daemon configuration file (Default: " CONFIGURATION_FILES_DIR "/dlt.conf)\n");
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
     printf("  -t directory  Directory for local fifo and user-pipes (Default: /tmp)\n");
     printf("                (Applications wanting to connect to a daemon using a\n");
     printf("                custom directory need to be started with the environment \n");
@@ -143,7 +152,7 @@ int option_handling(DltDaemonLocal *daemon_local, int argc, char *argv[])
     /* default values */
     daemon_local->flags.port = DLT_DAEMON_TCP_PORT;
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
     dlt_log_set_fifo_basedir(DLT_USER_IPC_PATH);
 #endif
 
@@ -171,7 +180,7 @@ int option_handling(DltDaemonLocal *daemon_local, int argc, char *argv[])
             strncpy(daemon_local->flags.cvalue, optarg, NAME_MAX);
             break;
         }
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
         case 't':
         {
             dlt_log_set_fifo_basedir(optarg);
@@ -224,7 +233,7 @@ int option_handling(DltDaemonLocal *daemon_local, int argc, char *argv[])
 
     /* switch() */
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
     snprintf(daemon_local->flags.userPipesDir, DLT_PATH_MAX,
              "%s/dltpipes", dltFifoBaseDir);
     snprintf(daemon_local->flags.daemonFifoName, DLT_PATH_MAX,
@@ -263,11 +272,11 @@ int option_file_parser(DltDaemonLocal *daemon_local)
     daemon_local->flags.loggingMode = DLT_LOG_TO_CONSOLE;
     daemon_local->flags.loggingLevel = LOG_INFO;
 
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_UNIX_SOCKET_IPC
     n = snprintf(daemon_local->flags.loggingFilename,
                  sizeof(daemon_local->flags.loggingFilename),
                  "%s/dlt.log", DLT_USER_IPC_PATH);
-#else
+#else /* DLT_DAEMON_USE_FIFO_IPC */
     n = snprintf(daemon_local->flags.loggingFilename,
                  sizeof(daemon_local->flags.loggingFilename),
                  "%s/dlt.log", dltFifoBaseDir);
@@ -298,14 +307,14 @@ int option_file_parser(DltDaemonLocal *daemon_local)
     strncpy(daemon_local->flags.ctrlSockPath,
             DLT_DAEMON_DEFAULT_CTRL_SOCK_PATH,
             sizeof(daemon_local->flags.ctrlSockPath) - 1);
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_UNIX_SOCKET_IPC
     snprintf(daemon_local->flags.appSockPath, DLT_IPC_PATH_MAX, "%s/dlt", DLT_USER_IPC_PATH);
 
     if (strlen(DLT_USER_IPC_PATH) > DLT_IPC_PATH_MAX)
         fprintf(stderr, "Provided path too long...trimming it to path[%s]\n",
                 daemon_local->flags.appSockPath);
 
-#else
+#else /* DLT_DAEMON_USE_FIFO_IPC */
     memset(daemon_local->flags.daemonFifoGroup, 0, sizeof(daemon_local->flags.daemonFifoGroup));
 #endif
     daemon_local->flags.gatewayMode = 0;
@@ -626,7 +635,7 @@ int option_file_parser(DltDaemonLocal *daemon_local)
                         }
                     }
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
                     else if (strcmp(token, "DaemonFifoGroup") == 0)
                     {
                         strncpy(daemon_local->flags.daemonFifoGroup, value, NAME_MAX);
@@ -728,7 +737,43 @@ int option_file_parser(DltDaemonLocal *daemon_local)
     return 0;
 }
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
+static int dlt_mkdir_recursive(const char *dir)
+{
+    int ret = 0;
+    char tmp[PATH_MAX + 1];
+    char *p = NULL;
+    char *end = NULL;
+    size_t len;
+
+    strncpy(tmp, dir, PATH_MAX);
+    len = strlen(tmp);
+
+    if (tmp[len - 1] == '/')
+        tmp[len - 1] = 0;
+
+    end = tmp + len;
+
+    for (p = tmp + 1; ((*p) && (ret == 0)) || ((ret == -1 && errno == EEXIST) && (p != end)); p++)
+        if (*p == '/') {
+            *p = 0;
+            ret = mkdir(tmp, S_IRWXU);
+            *p = '/';
+        }
+
+
+
+    if ((ret == 0) || ((ret == -1) && (errno == EEXIST)))
+        ret = mkdir(tmp, S_IRWXU);
+
+    if ((ret == -1) && (errno == EEXIST))
+        ret = 0;
+
+    return ret;
+}
+#endif
+
+#ifdef DLT_DAEMON_USE_FIFO_IPC
 static DltReturnValue dlt_daemon_create_pipes_dir(char *dir)
 {
     int ret = DLT_RETURN_OK;
@@ -811,7 +856,7 @@ int main(int argc, char *argv[])
 
     PRINT_FUNCTION_VERBOSE(daemon_local.flags.vflag);
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
 
     /* Make sure the parent user directory is created */
     if (dlt_mkdir_recursive(dltFifoBaseDir) != 0) {
@@ -979,7 +1024,7 @@ int dlt_daemon_local_init_p1(DltDaemon *daemon, DltDaemonLocal *daemon_local, in
 
 #endif
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
 
     if (dlt_daemon_create_pipes_dir(daemon_local->flags.userPipesDir) == DLT_RETURN_ERROR)
         return DLT_RETURN_ERROR;
@@ -1174,7 +1219,7 @@ static int dlt_daemon_init_serial(DltDaemonLocal *daemon_local)
                                  DLT_CONNECTION_CLIENT_MSG_SERIAL);
 }
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
 static int dlt_daemon_init_fifo(DltDaemonLocal *daemon_local)
 {
     int ret;
@@ -1254,6 +1299,43 @@ static int dlt_daemon_init_fifo(DltDaemonLocal *daemon_local)
 }
 #endif
 
+#ifdef DLT_DAEMON_VSOCK_IPC_ENABLE
+static int dlt_daemon_init_vsock(DltDaemonLocal *daemon_local)
+{
+    int fd;
+    struct sockaddr_vm addr;
+
+    fd = socket(AF_VSOCK, SOCK_STREAM, 0);
+    if (fd == -1) {
+        dlt_vlog(LOG_ERR, "Failed to create VSOCK socket: %s\n", strerror(errno));
+        return -1;
+    }
+
+    memset(&addr, 0, sizeof(addr));
+    addr.svm_family = AF_VSOCK;
+    addr.svm_port = DLT_VSOCK_PORT;
+    addr.svm_cid = VMADDR_CID_ANY;
+
+    if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) != 0) {
+        dlt_vlog(LOG_ERR, "Failed to bind VSOCK socket: %s\n", strerror(errno));
+        close(fd);
+        return -1;
+    }
+
+    if (listen(fd, 1) != 0) {
+        dlt_vlog(LOG_ERR, "Failed to listen on VSOCK socket: %s\n", strerror(errno));
+        close(fd);
+        return -1;
+    }
+
+    return dlt_connection_create(daemon_local,
+                                 &daemon_local->pEvent,
+                                 fd,
+                                 POLLIN,
+                                 DLT_CONNECTION_APP_CONNECT);
+}
+#endif
+
 int dlt_daemon_local_connection_init(DltDaemon *daemon,
                                      DltDaemonLocal *daemon_local,
                                      int verbose)
@@ -1269,7 +1351,7 @@ int dlt_daemon_local_connection_init(DltDaemon *daemon,
         return -1;
     }
 
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_UNIX_SOCKET_IPC
     /* create and open socket to receive incoming connections from user application
      * socket access permission set to srw-rw-rw- (666) */
     mask = S_IXUSR | S_IXGRP | S_IXOTH;
@@ -1292,7 +1374,7 @@ int dlt_daemon_local_connection_init(DltDaemon *daemon,
         return DLT_RETURN_ERROR;
     }
 
-#else
+#else /* DLT_DAEMON_USE_FIFO_IPC */
 
     if (dlt_daemon_init_fifo(daemon_local)) {
         dlt_log(LOG_ERR, "Unable to initialize fifo.\n");
@@ -1301,6 +1383,13 @@ int dlt_daemon_local_connection_init(DltDaemon *daemon,
 
 #endif
 
+#ifdef DLT_DAEMON_VSOCK_IPC_ENABLE
+    if (dlt_daemon_init_vsock(daemon_local) != 0) {
+        dlt_log(LOG_ERR, "Unable to initialize app VSOCK socket.\n");
+        return DLT_RETURN_ERROR;
+    }
+#endif
+
     /* create and open socket to receive incoming connections from client */
     daemon_local->client_connections = 0;
 
@@ -1484,10 +1573,10 @@ void dlt_daemon_local_cleanup(DltDaemon *daemon, DltDaemonLocal *daemon_local, i
     /* Ignore result */
     dlt_file_free(&(daemon_local->file), daemon_local->flags.vflag);
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
     /* Try to delete existing pipe, ignore result of unlink() */
     unlink(daemon_local->flags.daemonFifoName);
-#else
+#else /* DLT_DAEMON_USE_UNIX_SOCKET_IPC */
     /* Try to delete existing pipe, ignore result of unlink() */
     unlink(daemon_local->flags.appSockPath);
 #endif
@@ -1520,7 +1609,7 @@ void dlt_daemon_local_cleanup(DltDaemon *daemon, DltDaemonLocal *daemon_local, i
 void dlt_daemon_exit_trigger()
 {
 
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
     char tmp[DLT_PATH_MAX] = { 0 };
 
     ssize_t n;
@@ -1832,7 +1921,7 @@ int dlt_daemon_process_client_messages(DltDaemon *daemon,
         return -1;
     }
 
-    must_close_socket = dlt_receiver_receive(receiver, DLT_RECEIVE_SOCKET);
+    must_close_socket = dlt_receiver_receive(receiver);
 
     if (must_close_socket < 0) {
         dlt_daemon_close_socket(receiver->fd,
@@ -1908,7 +1997,7 @@ int dlt_daemon_process_client_messages_serial(DltDaemon *daemon,
         return -1;
     }
 
-    if (dlt_receiver_receive(receiver, DLT_RECEIVE_FD) <= 0) {
+    if (dlt_receiver_receive(receiver) <= 0) {
         dlt_log(LOG_WARNING,
                 "dlt_receiver_receive_fd() for messages from serial interface "
                 "failed!\n");
@@ -2010,15 +2099,13 @@ int dlt_daemon_process_control_connect(
     return 0;
 }
 
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#if defined DLT_DAEMON_USE_UNIX_SOCKET_IPC || defined DLT_DAEMON_VSOCK_IPC_ENABLE
 int dlt_daemon_process_app_connect(
     DltDaemon *daemon,
     DltDaemonLocal *daemon_local,
     DltReceiver *receiver,
     int verbose)
 {
-    socklen_t app_size;
-    struct sockaddr_un app;
     int in_sock = -1;
 
     PRINT_FUNCTION_VERBOSE(verbose);
@@ -2030,10 +2117,9 @@ int dlt_daemon_process_app_connect(
         return DLT_RETURN_WRONG_PARAMETER;
     }
 
-    /* event from UNIX server socket, new connection */
-    app_size = sizeof(app);
+    /* event from server socket, new connection */
 
-    if ((in_sock = accept(receiver->fd, (struct sockaddr *)&app, &app_size)) < 0) {
+    if ((in_sock = accept(receiver->fd, NULL, NULL)) < 0) {
         dlt_vlog(LOG_ERR, "accept() on UNIX socket %d failed: %s\n", receiver->fd, strerror(errno));
         return -1;
     }
@@ -2077,7 +2163,7 @@ int dlt_daemon_process_control_messages(
         return -1;
     }
 
-    if (dlt_receiver_receive(receiver, DLT_RECEIVE_SOCKET) <= 0) {
+    if (dlt_receiver_receive(receiver) <= 0) {
         dlt_daemon_close_socket(receiver->fd,
                                 daemon,
                                 daemon_local,
@@ -2189,28 +2275,21 @@ int dlt_daemon_process_user_messages(DltDaemon *daemon,
         return -1;
     }
 
-#ifdef DLT_USE_UNIX_SOCKET_IPC
-    recv = dlt_receiver_receive(receiver, DLT_RECEIVE_SOCKET);
+    recv = dlt_receiver_receive(receiver);
 
-    if (recv <= 0) {
+    if (recv <= 0 && receiver->type == DLT_RECEIVE_SOCKET) {
         dlt_daemon_close_socket(receiver->fd,
                                 daemon,
                                 daemon_local,
                                 verbose);
         return 0;
     }
-
-#else
-    recv = dlt_receiver_receive(receiver, DLT_RECEIVE_FD);
-
-    if (recv < 0) {
+    else if (recv < 0) {
         dlt_log(LOG_WARNING,
                 "dlt_receiver_receive_fd() for user messages failed!\n");
         return -1;
     }
 
-#endif
-
     /* look through buffer as long as data is in there */
     while ((receiver->bytesRcvd >= min_size) && run_loop) {
         dlt_daemon_process_user_message_func func = NULL;
@@ -2327,6 +2406,7 @@ int dlt_daemon_process_user_message_register_application(DltDaemon *daemon,
     char description[DLT_DAEMON_DESCSIZE + 1] = { '\0' };
     DltUserControlMsgRegisterApplication userapp;
     char *origin;
+    int fd = -1;
 
     PRINT_FUNCTION_VERBOSE(verbose);
 
@@ -2386,11 +2466,14 @@ int dlt_daemon_process_user_message_register_application(DltDaemon *daemon,
     if (old_application != NULL)
         old_pid = old_application->pid;
 
+    if (rec->type == DLT_RECEIVE_SOCKET)
+        fd = rec->fd; /* For sockets, an app specific fd has already been created with accept(). */
+
     application = dlt_daemon_application_add(daemon,
                                              userapp.apid,
                                              userapp.pid,
                                              description,
-                                             rec->fd,
+                                             fd,
                                              daemon->ecuid,
                                              verbose);
 
diff --git a/src/daemon/dlt-daemon.h b/src/daemon/dlt-daemon.h
index 31598bb..4095cf3 100644
--- a/src/daemon/dlt-daemon.h
+++ b/src/daemon/dlt-daemon.h
@@ -117,9 +117,9 @@ typedef struct
     unsigned int offlineLogstorageMaxCounter; /**< (int) Maximum offline logstorage file counter index until wraparound  */
     unsigned int offlineLogstorageMaxCounterIdx; /**< (int) String len of  offlineLogstorageMaxCounter*/
     unsigned int offlineLogstorageCacheSize; /**< Max cache size offline logstorage cache */
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_UNIX_SOCKET_IPC
     char appSockPath[DLT_DAEMON_FLAG_MAX]; /**< Path to User socket */
-#else
+#else /* DLT_DAEMON_USE_FIFO_IPC */
     char userPipesDir[DLT_PATH_MAX]; /**< (String: Directory) directory where dltpipes reside (Default: /tmp/dltpipes) */
     char daemonFifoName[DLT_PATH_MAX]; /**< (String: Filename) name of local fifo (Default: /tmp/dlt) */
     char daemonFifoGroup[DLT_PATH_MAX]; /**< (String: Group name) Owner group of local fifo (Default: Primary Group) */
@@ -209,7 +209,7 @@ int dlt_daemon_process_sixty_s_timer(DltDaemon *daemon, DltDaemonLocal *daemon_l
 int dlt_daemon_process_systemd_timer(DltDaemon *daemon, DltDaemonLocal *daemon_local, DltReceiver *recv, int verbose);
 
 int dlt_daemon_process_control_connect(DltDaemon *daemon, DltDaemonLocal *daemon_local, DltReceiver *recv, int verbose);
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#if defined DLT_DAEMON_USE_UNIX_SOCKET_IPC || defined DLT_DAEMON_VSOCK_IPC_ENABLE
 int dlt_daemon_process_app_connect(DltDaemon *daemon, DltDaemonLocal *daemon_local, DltReceiver *recv, int verbose);
 #endif
 int dlt_daemon_process_control_messages(DltDaemon *daemon, DltDaemonLocal *daemon_local, DltReceiver *recv,
diff --git a/src/daemon/dlt_daemon_common.c b/src/daemon/dlt_daemon_common.c
index f628cd5..4349753 100644
--- a/src/daemon/dlt_daemon_common.c
+++ b/src/daemon/dlt_daemon_common.c
@@ -65,6 +65,7 @@
  * aw          13.01.2010   initial
  */
 
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -384,6 +385,33 @@ int dlt_daemon_applications_clear(DltDaemon *daemon, char *ecu, int verbose)
     return 0;
 }
 
+static void dlt_daemon_application_reset_user_handle(DltDaemon *daemon,
+                                                     DltDaemonApplication *application,
+                                                     int verbose)
+{
+    DltDaemonRegisteredUsers *user_list;
+    DltDaemonContext *context;
+    int i;
+
+    if (application->user_handle == DLT_FD_INIT)
+        return;
+
+    user_list = dlt_daemon_find_users_list(daemon, daemon->ecuid, verbose);
+    if (user_list != NULL) {
+        for (i = 0; i < user_list->num_contexts; i++) {
+            context = &user_list->contexts[i];
+            if (context->user_handle == application->user_handle)
+                context->user_handle = DLT_FD_INIT;
+        }
+    }
+
+    if (application->owns_user_handle)
+        close(application->user_handle);
+
+    application->user_handle = DLT_FD_INIT;
+    application->owns_user_handle = false;
+}
+
 DltDaemonApplication *dlt_daemon_application_add(DltDaemon *daemon,
                                                  char *apid,
                                                  pid_t pid,
@@ -396,8 +424,9 @@ DltDaemonApplication *dlt_daemon_application_add(DltDaemon *daemon,
     DltDaemonApplication *old;
     int new_application;
     int dlt_user_handle;
+    bool owns_user_handle;
     DltDaemonRegisteredUsers *user_list = NULL;
-#ifndef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_FIFO_IPC
     (void)fd;  /* To avoid compiler warning : unused variable */
     char filename[DLT_DAEMON_COMMON_TEXTBUFSIZE];
 #endif
@@ -455,6 +484,7 @@ DltDaemonApplication *dlt_daemon_application_add(DltDaemon *daemon,
         application->application_description = NULL;
         application->num_contexts = 0;
         application->user_handle = DLT_FD_INIT;
+        application->owns_user_handle = false;
 
         new_application = 1;
 
@@ -487,42 +517,39 @@ DltDaemonApplication *dlt_daemon_application_add(DltDaemon *daemon,
         }
     }
 
-    if (application->user_handle != DLT_FD_INIT) {
-        if (application->pid != pid) {
-#ifndef DLT_USE_UNIX_SOCKET_IPC
-
-            if (close(application->user_handle) < 0)
-                dlt_vlog(LOG_WARNING,
-                         "close() failed to %s/dltpipes/dlt%d, errno=%d (%s)!\n",
-                         dltFifoBaseDir,
-                         pid,
-                         errno,
-                         strerror(errno)); /* errno 2: ENOENT - No such file or directory */
-
-#endif
-            application->user_handle = DLT_FD_INIT;
-            application->pid = 0;
-        }
+    if (application->pid != pid) {
+        dlt_daemon_application_reset_user_handle(daemon, application, verbose);
+        application->pid = 0;
     }
 
     /* open user pipe only if it is not yet opened */
     if ((application->user_handle == DLT_FD_INIT) && (pid != 0)) {
-#ifdef DLT_USE_UNIX_SOCKET_IPC
-        dlt_user_handle = fd;
-#else
-        snprintf(filename,
-                 DLT_DAEMON_COMMON_TEXTBUFSIZE,
-                 "%s/dltpipes/dlt%d",
-                 dltFifoBaseDir,
-                 pid);
-
-        dlt_user_handle = open(filename, O_WRONLY | O_NONBLOCK);
-
-        if (dlt_user_handle < 0) {
-            int prio = (errno == ENOENT) ? LOG_INFO : LOG_WARNING;
-            dlt_vlog(prio, "open() failed to %s, errno=%d (%s)!\n", filename, errno, strerror(errno));
-        } /* if */
+        dlt_user_handle = DLT_FD_INIT;
+        owns_user_handle = false;
 
+#if defined DLT_DAEMON_USE_UNIX_SOCKET_IPC || defined DLT_DAEMON_VSOCK_IPC_ENABLE
+        if (fd >= DLT_FD_MINIMUM) {
+            dlt_user_handle = fd;
+            owns_user_handle = false;
+        }
+#endif
+#ifdef DLT_DAEMON_USE_FIFO_IPC
+        if (dlt_user_handle < DLT_FD_MINIMUM) {
+            snprintf(filename,
+                     DLT_DAEMON_COMMON_TEXTBUFSIZE,
+                     "%s/dltpipes/dlt%d",
+                     dltFifoBaseDir,
+                     pid);
+
+            dlt_user_handle = open(filename, O_WRONLY | O_NONBLOCK);
+
+            if (dlt_user_handle < 0) {
+                int prio = (errno == ENOENT) ? LOG_INFO : LOG_WARNING;
+                dlt_vlog(prio, "open() failed to %s, errno=%d (%s)!\n", filename, errno, strerror(errno));
+            } else {
+                owns_user_handle = true;
+            }
+        }
 #endif
         /* check if file descriptor was already used, and make it invalid if it
         * is reused. This prevents sending messages to wrong file descriptor */
@@ -530,6 +557,7 @@ DltDaemonApplication *dlt_daemon_application_add(DltDaemon *daemon,
         dlt_daemon_contexts_invalidate_fd(daemon, ecu, dlt_user_handle, verbose);
 
         application->user_handle = dlt_user_handle;
+        application->owns_user_handle = owns_user_handle;
         application->pid = pid;
     }
 
@@ -566,13 +594,7 @@ int dlt_daemon_application_del(DltDaemon *daemon,
         return -1;
 
     if (user_list->num_applications > 0) {
-        /* Check if user handle is open; if yes, close it */
-        if (application->user_handle >= DLT_FD_MINIMUM) {
-#ifndef DLT_USE_UNIX_SOCKET_IPC
-            close(application->user_handle);
-#endif
-            application->user_handle = DLT_FD_INIT;
-        }
+        dlt_daemon_application_reset_user_handle(daemon, application, verbose);
 
         /* Free description of application to be deleted */
         if (application->application_description) {
@@ -1325,6 +1347,7 @@ int dlt_daemon_user_send_log_level(DltDaemon *daemon, DltDaemonContext *context,
     DltUserHeader userheader;
     DltUserControlMsgLogLevel usercontext;
     DltReturnValue ret;
+    DltDaemonApplication *app;
 
     PRINT_FUNCTION_VERBOSE(verbose);
 
@@ -1370,11 +1393,9 @@ int dlt_daemon_user_send_log_level(DltDaemon *daemon, DltDaemonContext *context,
                  errno != 0 ? strerror(errno) : "Unknown error");
 
         if (errno == EPIPE) {
-#ifndef DLT_USE_UNIX_SOCKET_IPC
-            /* Close connection */
-            close(context->user_handle);
-#endif
-            context->user_handle = DLT_FD_INIT;
+            app = dlt_daemon_application_find(daemon, context->apid, daemon->ecuid, verbose);
+            if (app != NULL)
+                dlt_daemon_application_reset_user_handle(daemon, app, verbose);
         }
     }
 
@@ -1403,13 +1424,8 @@ int dlt_daemon_user_send_log_state(DltDaemon *daemon, DltDaemonApplication *app,
                             &(logstate), sizeof(DltUserControlMsgLogState));
 
     if (ret < DLT_RETURN_OK) {
-        if (errno == EPIPE) {
-#ifndef DLT_USE_UNIX_SOCKET_IPC
-            /* Close connection */
-            close(app->user_handle);
-#endif
-            app->user_handle = DLT_FD_INIT;
-        }
+        if (errno == EPIPE)
+            dlt_daemon_application_reset_user_handle(daemon, app, verbose);
     }
 
     return (ret == DLT_RETURN_OK) ? DLT_RETURN_OK : DLT_RETURN_ERROR;
diff --git a/src/daemon/dlt_daemon_common.h b/src/daemon/dlt_daemon_common.h
index 5e1bb1b..c6a4594 100644
--- a/src/daemon/dlt_daemon_common.h
+++ b/src/daemon/dlt_daemon_common.h
@@ -133,6 +133,7 @@ typedef struct
     char apid[DLT_ID_SIZE];                   /**< application id */
     pid_t pid;                   /**< process id of user application */
     int user_handle;    /**< connection handle for connection to user application */
+    bool owns_user_handle; /**< user_handle should be closed when reset */
     char *application_description; /**< context description */
     int num_contexts; /**< number of contexts for this application */
 } DltDaemonApplication;
diff --git a/src/daemon/dlt_daemon_common_cfg.h b/src/daemon/dlt_daemon_common_cfg.h
index 926befd..8fbd9b0 100644
--- a/src/daemon/dlt_daemon_common_cfg.h
+++ b/src/daemon/dlt_daemon_common_cfg.h
@@ -86,7 +86,7 @@
 #define DLT_DAEMON_DEFAULT_CTRL_SOCK_PATH DLT_RUNTIME_DEFAULT_DIRECTORY \
     "/dlt-ctrl.sock"
 
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#ifdef DLT_DAEMON_USE_UNIX_SOCKET_IPC
 #   define DLT_DAEMON_DEFAULT_APP_SOCK_PATH DLT_RUNTIME_DEFAULT_DIRECTORY \
     "/dlt-app.sock"
 #endif
diff --git a/src/daemon/dlt_daemon_connection.c b/src/daemon/dlt_daemon_connection.c
index 43a202b..a438c03 100644
--- a/src/daemon/dlt_daemon_connection.c
+++ b/src/daemon/dlt_daemon_connection.c
@@ -33,6 +33,7 @@
 
 #include <sys/socket.h>
 #include <syslog.h>
+#include <sys/stat.h>
 #include <sys/types.h>
 
 #include "dlt_daemon_connection_types.h"
@@ -162,7 +163,7 @@ DLT_STATIC void dlt_connection_destroy_receiver(DltConnection *con)
         /* We rely on the gateway for clean-up */
         break;
     case DLT_CONNECTION_APP_MSG:
-        dlt_receiver_free_unix_socket(con->receiver);
+        dlt_receiver_free_global_buffer(con->receiver);
         free(con->receiver);
         con->receiver = NULL;
         break;
@@ -193,6 +194,8 @@ DLT_STATIC DltReceiver *dlt_connection_get_receiver(DltDaemonLocal *daemon_local
                                                     int fd)
 {
     DltReceiver *ret = NULL;
+    DltReceiverType receiver_type = DLT_RECEIVE_FD;
+    struct stat statbuf;
 
     switch (type) {
     case DLT_CONNECTION_CONTROL_CONNECT:
@@ -205,29 +208,34 @@ DLT_STATIC DltReceiver *dlt_connection_get_receiver(DltDaemonLocal *daemon_local
         ret = calloc(1, sizeof(DltReceiver));
 
         if (ret)
-            dlt_receiver_init(ret, fd, DLT_DAEMON_RCVBUFSIZESOCK);
+            dlt_receiver_init(ret, fd, DLT_RECEIVE_SOCKET, DLT_DAEMON_RCVBUFSIZESOCK);
 
         break;
     case DLT_CONNECTION_CLIENT_MSG_SERIAL:
         ret = calloc(1, sizeof(DltReceiver));
 
         if (ret)
-            dlt_receiver_init(ret, fd, DLT_DAEMON_RCVBUFSIZESERIAL);
+            dlt_receiver_init(ret, fd, DLT_RECEIVE_FD, DLT_DAEMON_RCVBUFSIZESERIAL);
 
         break;
     case DLT_CONNECTION_APP_MSG:
         ret = calloc(1, sizeof(DltReceiver));
 
-        if (ret) {
-            #ifdef DLT_USE_UNIX_SOCKET_IPC
-            dlt_receiver_init_unix_socket(ret, fd, &app_recv_buffer);
-            #else
-            dlt_receiver_init(ret, fd, DLT_RECEIVE_BUFSIZE);
-            #endif
+        receiver_type = DLT_RECEIVE_FD;
+
+        if (fstat(fd, &statbuf) == 0) {
+            if (S_ISSOCK(statbuf.st_mode))
+                receiver_type = DLT_RECEIVE_SOCKET;
+        } else {
+            dlt_vlog(LOG_WARNING,
+                     "Failed to determine receive type for DLT_CONNECTION_APP_MSG, using \"FD\"\n");
         }
 
+        if (ret)
+            dlt_receiver_init_global_buffer(ret, fd, receiver_type, &app_recv_buffer);
+
         break;
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#if defined DLT_DAEMON_USE_UNIX_SOCKET_IPC || defined DLT_DAEMON_VSOCK_IPC_ENABLE
     case DLT_CONNECTION_APP_CONNECT:
     /* FALL THROUGH */
 #endif
@@ -243,7 +251,7 @@ DLT_STATIC DltReceiver *dlt_connection_get_receiver(DltDaemonLocal *daemon_local
         ret = calloc(1, sizeof(DltReceiver));
 
         if (ret)
-            dlt_receiver_init(ret, fd, DLT_DAEMON_RCVBUFSIZE);
+            dlt_receiver_init(ret, fd, DLT_RECEIVE_FD, DLT_DAEMON_RCVBUFSIZE);
 
         break;
     case DLT_CONNECTION_GATEWAY:
@@ -286,7 +294,7 @@ void *dlt_connection_get_callback(DltConnection *con)
     case DLT_CONNECTION_CLIENT_MSG_SERIAL:
         ret = dlt_daemon_process_client_messages_serial;
         break;
-#ifdef DLT_USE_UNIX_SOCKET_IPC
+#if defined DLT_DAEMON_USE_UNIX_SOCKET_IPC || defined DLT_DAEMON_VSOCK_IPC_ENABLE
     case DLT_CONNECTION_APP_CONNECT:
         ret = dlt_daemon_process_app_connect;
         break;