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

[citadel.git] / citadel / domain.c

diff --git a/citadel/domain.c b/citadel/domain.c
index 69376cbb0b5d16a541c47479917a3b1725704f10..f64458ed408f303b6a42486475bff619cba072b6 100644 (file)
--- 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));