Pick up the first section if given section(domain) doesn't match anything

As some clinents (AFAIK Windows 10) always send domain name, the backend
module is not selected properly. This causes the default usage with
Windows 10 fails with 'xrdp_wm_log_msg: Section "XXX" not configured'.

xrdp/xrdp_wm.c

@@ -554,6 +554,7 @@ xrdp_wm_init(struct xrdp_wm *self)
     char *q;
     const char *r;
     char param[256];
+    char default_section_name[256];
     char section_name[256];
     char cfg_file[256];
     char autorun_name[256];
@@ -581,6 +582,22 @@ xrdp_wm_init(struct xrdp_wm *self)
             values = list_create();
             values->auto_free = 1;
 
+            /* pick up the first section name except for 'globals', 'Logging', 'channels'
+             * in xrdp.ini and use it as default section name */
+            file_read_sections(fd, names);
+            default_section_name[0] = '\0';
+            for (index = 0; index < names->count; index++)
+            {
+                q = (char *)list_get_item(names, index);
+                if ((g_strncasecmp("globals", q, 8) != 0) &&
+                    (g_strncasecmp("Logging", q, 8) != 0) &&
+                    (g_strncasecmp("channels", q, 9) != 0))
+                {
+                    g_strncpy(default_section_name, q, 255);
+                    break;
+                }
+            }
+
             /* look for module name to be loaded */
             if (autorun_name[0] != 0)
             {
@@ -594,34 +611,36 @@ xrdp_wm_init(struct xrdp_wm *self)
                  * simplify for the user in a proxy setup */
 
                 /* we use the domain name as the module name to be loaded */
-                g_strncpy(section_name, self->session->client_info->domain,
-                              255);
+                g_strncpy(section_name,
+                          self->session->client_info->domain, 255);
             }
             else
             {
-                /* if no domain is passed, and no autorun in xrdp.ini,
-                   use the first item in the xrdp.ini
-                   file that's not named
-                   'globals' or 'Logging' or 'channels' */
-                /* TODO: change this and have an 'autologin'
-                   line in globals section */
-                file_read_sections(fd, names);
-                section_name[0] = '\0';
-                for (index = 0; index < names->count; index++)
-                {
-                    q = (char *)list_get_item(names, index);
-                    if ((g_strncasecmp("globals", q, 8) != 0) &&
-                        (g_strncasecmp("Logging", q, 8) != 0) &&
-                        (g_strncasecmp("channels", q, 9) != 0))
-                    {
-                        g_strncpy(section_name, q, 255);
-                        break;
-                    }
-                }
+                /* if no domain is given, and autorun is not specified in xrdp.ini
+                 * use default_section_name as section_name  */
+                g_strncpy(section_name, default_section_name, 255);
             }
 
             list_clear(names);
 
+            /* if given section name doesn't match any sections configured
+             * in xrdp.ini, fallback to default_section_name */
+            if (file_read_section(fd, section_name, names, values) != 0)
+            {
+                log_message(LOG_LEVEL_INFO,
+                            "Module \"%s\" specified by %s from %s port %s "
+                            "is not configured. Using \"%s\" instead.",
+                            section_name,
+                            self->session->client_info->username,
+                            self->session->client_info->client_addr,
+                            self->session->client_info->client_port,
+                            default_section_name);
+                list_clear(names);
+                list_clear(values);
+
+                g_strncpy(section_name, default_section_name, 255);
+            }
+
             /* look for the required module in xrdp.ini, fetch its parameters */
             if (file_read_section(fd, section_name, names, values) == 0)
             {
@@ -684,10 +703,9 @@ xrdp_wm_init(struct xrdp_wm *self)
             }
             else
             {
-                /* requested module name not found in xrdp.ini */
-                xrdp_wm_log_msg(self, LOG_LEVEL_ERROR,
-                                "Section \"%s\" not configured in xrdp.ini",
-                                section_name);
+                /* Hopefully, we never reach here. */
+                log_message(LOG_LEVEL_DEBUG,
+                            "Control should never reach %s:%d", __FILE__, __LINE__);
             }
 
             list_delete(names);