From: Art Cancro <ajc@citadel.org>
Date: Sat, 1 Dec 2001 17:00:23 +0000 (+0000)
Subject: * serv_smtp.c: when multiple MX's are the same preference, randomize them
X-Git-Tag: v7.86~6721
X-Git-Url: https://code.citadel.org/?p=citadel.git;a=commitdiff_plain;h=cc6b14b4fcf02e58135c04d5b8c0ae95b121b44e

* serv_smtp.c: when multiple MX's are the same preference, randomize them
---

diff --git a/citadel/ChangeLog b/citadel/ChangeLog
index 713cc019c..559e733df 100644
--- a/citadel/ChangeLog
+++ b/citadel/ChangeLog
@@ -1,4 +1,7 @@
  $Log$
+ Revision 580.82  2001/12/01 17:00:23  ajc
+ * serv_smtp.c: when multiple MX's are the same preference, randomize them
+
  Revision 580.81  2001/12/01 07:18:28  ajc
  * Fixed an SMTP delivery problem that was causing certain classes of
    transient errors to cause a message to never be delivered.
@@ -2886,3 +2889,4 @@ Sat Jul 11 00:20:48 EDT 1998 Nathan Bryant <bryant@cs.usm.maine.edu>
 
 Fri Jul 10 1998 Art Cancro <ajc@uncensored.citadel.org>
 	* Initial CVS import 
+
diff --git a/citadel/domain.c b/citadel/domain.c
index 69376cbb0..f64458ed4 100644
--- a/citadel/domain.c
+++ b/citadel/domain.c
@@ -52,6 +52,22 @@ int get_smarthosts(char *mxbuf) {
 }
 
 
+/*
+ * Compare the preference of two MX records.  First check by the actual
+ * number listed in the MX record.  If they're identical, randomize the
+ * result.
+ */
+inline int mx_compare_pref(int pref1, int pref2) {
+	if (pref1 > pref2) {
+		return(1);
+	}
+	else if (pref1 < pref2) {
+		return(1);
+	}
+	else {
+		return(rand() % 2);
+	}
+}
 
 
 /*
@@ -69,8 +85,7 @@ void sort_mxrecs(struct mx *mxrecs, int num_mxrecs) {
 	/* do the sort */
 	for (a = num_mxrecs - 2; a >= 0; --a) {
 		for (b = 0; b <= a; ++b) {
-			if (mxrecs[b].pref > mxrecs[b+1].pref) {
-
+			if (mx_compare_pref(mxrecs[b].pref,mxrecs[b+1].pref)) {
 				memcpy(&hold1, &mxrecs[b], sizeof(struct mx));
 				memcpy(&hold2, &mxrecs[b+1], sizeof(struct mx));
 				memcpy(&mxrecs[b], &hold2, sizeof(struct mx));