Add restartability to sesman

common/os_calls.c

@@ -37,6 +37,7 @@
 #define ctid_t id_t
 #endif
 #include <unistd.h>
+#include <dirent.h>
 #include <errno.h>
 #include <netinet/in.h>
 #include <netinet/tcp.h>
@@ -2588,6 +2589,23 @@ g_executable_exist(const char *exename)
     return access(exename, R_OK | X_OK) == 0;
 }
 
+/*****************************************************************************/
+/* returns boolean, non zero if the socket exists */
+int
+g_socket_exist(const char *sockname)
+{
+    struct stat st;
+
+    if (stat(sockname, &st) == 0)
+    {
+        return S_ISSOCK(st.st_mode);
+    }
+    else
+    {
+        return 0;
+    }
+}
+
 /*****************************************************************************/
 /* returns boolean */
 int
@@ -4200,3 +4218,61 @@ g_qsort(void *base, size_t nitems, size_t size,
 {
     qsort(base, nitems, size, compar);
 }
+
+/*****************************************************************************/
+struct list *
+g_readdir(const char *dir)
+{
+    DIR *handle;
+    struct list *result = NULL;
+    struct dirent *dent;
+    int saved_errno;
+
+    errno = 0; // See readdir(3)
+    if ((handle = opendir(dir)) != NULL &&
+            (result = list_create()) != NULL)
+    {
+        result->auto_free = 1;
+        while (1)
+        {
+            errno = 0;
+            dent = readdir(handle);
+            if (dent == NULL)
+            {
+                break; // errno = 0 for end-of-dir, or != 0 for error
+            }
+
+            // Ignore '.' and '..'
+            if (dent->d_name[0] == '.' && dent->d_name[1] == '\0')
+            {
+                continue;
+            }
+            if (dent->d_name[0] == '.' && dent->d_name[1] == '.' &&
+                    dent->d_name[2] == '\0')
+            {
+                continue;
+            }
+
+            if (!list_add_strdup(result, dent->d_name))
+            {
+                // Memory allocation failure
+                errno = ENOMEM;
+                break;
+            }
+        }
+    }
+
+    saved_errno = errno;
+    if (errno != 0)
+    {
+        list_delete(result);
+        result = NULL;
+    }
+    if (handle != NULL)
+    {
+        closedir(handle);
+    }
+    errno = saved_errno;
+
+    return result;
+}

common/os_calls.h

@@ -258,6 +258,7 @@ int      g_file_exist(const char *filename);
 int      g_file_readable(const char *filename);
 int      g_directory_exist(const char *dirname);
 int      g_executable_exist(const char *dirname);
+int      g_socket_exist(const char *dirname);
 int      g_create_dir(const char *dirname);
 int      g_create_path(const char *path);
 int      g_remove_dir(const char *dirname);
@@ -428,6 +429,19 @@ void
 g_qsort(void *base, size_t nitems, size_t size,
         int (*compar)(const void *, const void *));
 
+/**
+ * Returns a list of the filenames contained within a directory
+ *
+ * @param dir Name of directory
+ * @return list of directory entry names
+ *
+ * If NULL is returned, further information may be available in errno. No
+ * other errors are specifically logged.
+ * The special files '.' and '..' are not returned.
+ */
+struct list *
+g_readdir(const char *dir);
+
 /* glib-style wrappers */
 #define g_new(struct_type, n_structs) \
     (struct_type *) malloc(sizeof(struct_type) * (n_structs))

instfiles/xrdp.service.in

@@ -11,6 +11,13 @@ EnvironmentFile=-@sysconfdir@/default/xrdp
 ExecStart=@sbindir@/xrdp $XRDP_OPTIONS --nodaemon
 SystemCallArchitectures=native
 SystemCallFilter=@system-service
+# Uncomment the following line if you wish xrdp connections to survive
+# an xrdp restart.
+#
+# This is not recommended, as the xrdp and xrdp-sesman processes can
+# end up with API differences if the restart was caused by an upgrade. It
+# may however be useful for some use cases.
+#KillMode=process
 
 [Install]
 WantedBy=multi-user.target

libipm/ercp.c

@@ -81,6 +81,32 @@ ercp_trans_from_eicp_trans(struct trans *trans,
 
 /*****************************************************************************/
 
+struct trans *
+ercp_connect(const  char *port, int (*term_func)(void))
+{
+    struct trans *t;
+
+    if ((t = trans_create(TRANS_MODE_UNIX, 128, 128)) != NULL)
+    {
+        t->is_term = term_func;
+
+        if (trans_connect(t, NULL, port, 3000) != 0)
+        {
+            trans_delete(t);
+            t = NULL;
+        }
+        else if (ercp_init_trans(t) != 0)
+        {
+            trans_delete(t);
+            t = NULL;
+        }
+    }
+
+    return t;
+}
+
+/*****************************************************************************/
+
 int
 ercp_msg_in_check_available(struct trans *trans, int *available)
 {
@@ -182,10 +208,7 @@ ercp_get_session_announce_event(struct trans *trans,
 
     if (rv == 0)
     {
-        if (display != NULL)
-        {
-            *display = i_display;
-        }
+        *display = i_display;
         *uid = (uid_t)i_uid;
         *type = (enum scp_session_type)i_type;
         *start_width = i_width;

libipm/ercp.h

@@ -88,6 +88,16 @@ ercp_trans_from_eicp_trans(struct trans *trans,
                            ttrans_data_in callback_func,
                            void *callback_data);
 
+/**
+ * Connects to an ERCP endpoint.
+ *
+ * @param port Path to UDS object in filesystem
+ * @param term_func Function to poll during connection for program
+ *         termination, or NULL for none.
+ */
+struct trans *
+ercp_connect(const char *port,
+             int (*term_func)(void));
 
 /**
  * Checks an ERCP transport to see if a complete message is
@@ -178,7 +188,6 @@ ercp_send_session_announce_event(struct trans *trans,
  *
  * @param trans EICP transport
  * @param[out] display Display used by session.
- *             Pointer can be NULL if this is already known.
  * @param[out] uid UID of user logged in to session
  * @param[out] type Session type
  * @param[out] start_width Starting width of seenio

sesman/Makefile.am

@@ -32,6 +32,8 @@ xrdp_sesman_SOURCES = \
   sesexec_control.h \
   session_list.c \
   session_list.h \
+  sesman_restart.c \
+  sesman_restart.h \
   sig.c \
   sig.h
 

sesman/ercp_process.c

@@ -42,9 +42,10 @@ process_session_announce_event(struct session_item *si)
 {
     int rv;
     const char *start_ip_addr;
+    unsigned int display;
 
     rv = ercp_get_session_announce_event(si->sesexec_trans,
-                                         NULL,
+                                         &display,
                                          &si->uid,
                                          &si->type,
                                          &si->start_width,
@@ -53,10 +54,24 @@ process_session_announce_event(struct session_item *si)
                                          &si->guid,
                                          &start_ip_addr,
                                          &si->start_time);
+    if (rv == 0)
+    {
+        // We may already know the display we sent sesexec. If we do,
+        // check sesexec sent the same value back.
+        if (si->display >= 0 && display != (unsigned int)si->display)
+        {
+            LOG(LOG_LEVEL_ERROR, "Bugcheck: sesman expected display %d, got %u",
+                si->display, display);
+            rv = 1;
+        }
+    }
+
     if (rv == 0)
     {
         snprintf(si->start_ip_addr, sizeof(si->start_ip_addr),
                  "%s", start_ip_addr);
+        si->display = display;
+
         si->state = E_SESSION_RUNNING;
     }
 

sesman/libsesman/sesman_config.h

@@ -183,8 +183,11 @@ struct config_sesman
     /**
      * @var listen_port
      * @brief Listening port
+     *
+     * This string is used to form the restart directory name, so
+     * can't be the full XRDP_SOCKETS_MAXPATH length.
      */
-    char listen_port[XRDP_SOCKETS_MAXPATH];
+    char listen_port[XRDP_SOCKETS_MAXPATH - 10];
     /**
      * @var enable_user_wm
      * @brief Flag that enables user specific wm

sesman/sesexec/Makefile.am

@@ -29,6 +29,8 @@ xrdp_sesexec_SOURCES = \
   env.h \
   login_info.c \
   login_info.h \
+  sesexec_discover.c \
+  sesexec_discover.h \
   sessionrecord.c \
   sessionrecord.h \
   xauth.c \