[PATCH] xauth: improve to handle FamilyWild necessary for GDM/XDMCP/SSH. #43425

[Dr. Tilmann Bubeck]

From: "Dr. Tilmann Bubeck" <t.bubeck at reinform.de>

xauth is currently unable to handle FamilyWild. This gives problems
with GDM receiving XDMCP request which used FamilyWild. More details
in the referenced freedesktop bugzilla entry.

The patch improves xauth to handle that Family:
  * allow "dump_entry" to deal with that Family and output
    such entries correctly.
  * allow "list $DISPLAY" to match against an entry in
    XAUTHORITY of type FamilyWild.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=43425

Signed-off-by: Dr. Tilmann Bubeck <t.bubeck at reinform.de>
---
 process.c |   55 ++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/process.c b/process.c
index 283b4a1..651bea0 100644
--- a/process.c
+++ b/process.c
@@ -462,6 +462,9 @@ read_auth_entries(FILE *fp, Bool numeric, AuthList **headp, AuthList **tailp)
     return n;
 }
 
+/**
+ * Parse the given displayname and build a corresponding AuthList.
+ */
 static Bool
 get_displayname_auth(const char *displayname, AuthList **authl)
 {
@@ -991,6 +994,9 @@ dump_entry(const char *inputfilename, int lineno, Xauth *auth, char *data)
 	    fwrite (auth->address, sizeof (char), auth->address_length, fp);
 	    fprintf (fp, "/unix");
 	    break;
+  	  case FamilyWild:
+	    fwrite (auth->address, sizeof (char), auth->address_length, fp);
+	    break;
 	  case FamilyInternet:
 #if defined(IPv6) && defined(AF_INET6)
 	  case FamilyInternet6:
@@ -1073,6 +1079,32 @@ match_auth_dpy(register Xauth *a, register Xauth *b)
 	     memcmp(a->number, b->number, a->number_length) == 0) ? 1 : 0);
 }
 
+static int 
+match_authwild_dpy(register Xauth *a, const char *displayname)
+{
+    int family;
+    char *host = NULL, *rest = NULL;
+    int dpynum, scrnum;
+    char dpynumbuf[40];			/* want to hold largest display num */
+
+    if ( a->family != FamilyWild ) {
+	return False;
+    }
+
+    if (!parse_displayname (displayname,
+			    &family, &host, &dpynum, &scrnum, &rest)) {
+	return False;
+    }
+
+    dpynumbuf[0] = '\0';
+    sprintf (dpynumbuf, "%d", dpynum);
+
+    return ((a->address_length == strlen(host) &&
+	     a->number_length == strlen(dpynumbuf) &&
+	     memcmp(a->address, host, a->address_length) == 0 &&
+	     memcmp(a->number, dpynumbuf, a->number_length) == 0) ? 1 : 0);
+}
+
 /* return non-zero iff display and authorization type are the same */
 
 static int
@@ -1236,13 +1268,22 @@ iterdpy (const char *inputfilename, int lineno, int start,
 	    /* l may be freed by remove_entry below. so save its contents */
 	    next = l->next;
 	    tmp_auth = copyAuth(l->auth);
-	    for (proto = proto_head; proto; proto = proto->next) {
-		if (match_auth_dpy (proto->auth, tmp_auth)) {
-		    matched = True;
-		    if (yfunc) {
-			status = (*yfunc) (inputfilename, lineno,
-					   tmp_auth, data);
-			if (status < 0) break;
+
+	    if ( match_authwild_dpy(tmp_auth, displayname) ) {
+	        matched = True;
+		if (yfunc) {
+		    status = (*yfunc) (inputfilename, lineno,
+				       tmp_auth, data);
+		}
+	    } else {
+	        for (proto = proto_head; proto; proto = proto->next) {
+		    if (match_auth_dpy (proto->auth, tmp_auth)) {
+		        matched = True;
+		        if (yfunc) {
+			    status = (*yfunc) (inputfilename, lineno,
+				   	       tmp_auth, data);
+			    if (status < 0) break;
+			}
 		    }
 		}
 	    }
-- 
1.7.7.3