regression: Display number related issues

The move away from the X11 display number has introduced a couple of regressions
1) XDG_SESSION_TYPE is not detected properly.

   pam_systemd.so contains code to map a PAM_TTY of ':n' to an 'x11'
   session type. This mapping is no longer done. We could re-introduce
   this code for X11, but there is no such code to detect a wayland
   display type. We try to fix this in a forward-looking way by setting
   XDG_SESSION_TYPE explicity before starting the PAM session.

2) utmp is not being updated correctly.

   The code for setting ut_id in the utmp[x] structure was setting the
   same value for all X11 displays, thus preventing utmp from being able
   to see more than one xrdp user

Also, an include is needed for sesman/eicp_process.c on some systems to
get access to strlcpy()

sesman/eicp_process.c

@@ -40,6 +40,7 @@
 #include "sesman.h"
 #include "sesman_access.h"
 #include "sesman_config.h"
+#include "string_calls.h"
 #include "guid.h"
 
 /******************************************************************************/

sesman/libsesman/verify_user_pam.c

@@ -400,9 +400,20 @@ auth_uds(const char *user, enum scp_login_status *errorcode)
 static int
 auth_start_session_private(struct auth_info *auth_info, const char *display)
 {
-    int error;
+    // For Linux and maybe other systems, pam_systemd needs to know the
+    // session type in order to set the session up correctly
+    const char *session_type;
+    if (g_get_x11_display_from_display_string(display) >= 0)
+    {
+        session_type = "x11";
+    }
+    else
+    {
+        session_type = "wayland";
+    }
+    g_setenv_log("XDG_SESSION_TYPE", session_type, 1);
 
-    error = pam_set_item(auth_info->ph, PAM_TTY, display);
+    int error = pam_set_item(auth_info->ph, PAM_TTY, display);
 
     if (error != PAM_SUCCESS)
     {

sesman/libsesman/verify_user_pam_userpass.c

@@ -209,9 +209,20 @@ auth_uds(const char *user, enum scp_login_status *errorcode)
 static int
 auth_start_session_private(struct auth_info *auth_info, const char *display)
 {
-    int error;
+    // For Linux and maybe other systems, pam_systemd needs to know the
+    // session type in order to set the session up correctly
+    const char *session_type;
+    if (g_get_x11_display_from_display_string(display) >= 0)
+    {
+        session_type = "x11";
+    }
+    else
+    {
+        session_type = "wayland";
+    }
+    g_setenv_log("XDG_SESSION_TYPE", session_type, 1);
 
-    error = pam_set_item(auth_info->ph, PAM_TTY, display);
+    int error = pam_set_item(auth_info->ph, PAM_TTY, display);
 
     if (error != PAM_SUCCESS)
     {

sesman/sesexec/sessionrecord.c

@@ -71,9 +71,9 @@ typedef struct utmp _utmp;
 #include "string_calls.h"
 
 #define XRDP_LINE_FORMAT "xrdp:%s"
-// ut_id is a very small field on some platforms, so use the display
-// number in hex
-#define XRDP_ID_FORMAT ":%x"
+// ut_id is a very small field on some platforms, so use a discriminator
+// (e.g. ':' for x11) and a number in hex
+#define XRDP_ID_FORMAT "%c%x"
 
 /******************************************************************************/
 /**
@@ -106,30 +106,46 @@ str2memcpy(void *dest, const char *src, size_t n)
 
 /******************************************************************************/
 /**
- * Get a display number from the display string
+ * Set the idbuff string
  *
- * Converts the display string to some sort of number to write to the
- * extremely short ut_id field
- * @param display string
- * @return display number
+ * The ut_id field is extremely short (e.g. 4 usable characters on
+ * Linux/FreeBSD).
+ *
+ * @param buff Output buffer, including terminator
+ * @param bufflen Length of above
+ * @param display Display string for the session
  */
-static unsigned int
-get_display_num(const char *display)
+static void
+set_idbuff_str(char buff[], unsigned int bufflen, const char *display)
 {
-    unsigned int result = 0;
+    unsigned int display_num = 0;
+    char discriminator;
+
+    // X11 display?
+    int x11_display = g_get_x11_display_from_display_string(display);
+    if (x11_display >= 0)
+    {
+        discriminator = ':';
+        display_num = (unsigned int)x11_display;
+    }
+    else
+    {
+        discriminator = 'W';
         /* Look for the first digit in the string */
         while (*display != '\0' && !isdigit(*display))
         {
             ++display;
         }
         /* convert consecutive digits to a number */
+        display_num = 0;
         while (*display != '\0' && isdigit(*display))
         {
-        result = (result * 10) + (*display - '0');
+            display_num = (display_num * 10) + (*display - '0');
             ++display;
         }
-
-    return result;
+    }
+    display_num = MIN(display_num, 0xfff);
+    g_snprintf(buff, bufflen, XRDP_ID_FORMAT, discriminator, display_num);
 }
 
 /******************************************************************************/
@@ -158,11 +174,8 @@ add_xtmp_entry(int pid, const char *display,
 
     struct timeval tv;
 
-    /* Convert the display string to a number */
-    unsigned int display_num = get_display_num(display);
-
     g_memset(&ut, 0, sizeof(ut));
-    g_snprintf(idbuff, sizeof(idbuff), XRDP_ID_FORMAT, display_num);
+    set_idbuff_str(idbuff, sizeof(idbuff), display);
     g_snprintf(linebuff, sizeof(linebuff), XRDP_LINE_FORMAT, display);
     gettimeofday(&tv, NULL);