Re: can anybody review my patchset?

On Mon, Apr 20, 2009 at 12:29 AM, Andreas Schulze
<[email protected]> wrote:
> 9. own Patch: let tinydns rotate multiple MX records

If anyone really needs this functionality, I've rewritten this patch below.

However, I do not recommend this patch for general use.  If you have
more than 8 MX records for a single domain name, it can cause mail
delivery failures.

--- tdlookup.c.orig	2009-04-20 10:09:28.000000000 -0700
+++ tdlookup.c	2009-04-20 10:12:18.000000000 -0700
@@ -103,6 +103,14 @@
   return response_addname(d1);
 }

+static void swapnames(char **a,char **b)
+{
+  char *t;
+  t = *a;
+  *a = *b;
+  *b = t;
+}
+
 static int doit(char *q,char qtype[2])
 {
   unsigned int bpos;
@@ -121,6 +129,10 @@
   char addr[8][4];
   int addrnum;
   uint32 addrttl;
+  char mxdist[8][2];
+  static char *mxname[8];
+  int mxnum;
+  uint32 mxttl;
   int i;

   anpos = response_len;
@@ -154,6 +166,7 @@
   for (;;) {
     addrnum = 0;
     addrttl = 0;
+    mxnum = 0;
     cdb_findstart(&c);
     while (r = find(wild,wild != q)) {
       if (r == -1) return 0;
@@ -171,14 +184,26 @@
 	if (addrnum < 1000000) ++addrnum;
 	continue;
       }
+      if (byte_equal(type,2,DNS_T_MX)) {
+        dpos = dns_packet_copy(data,dlen,dpos,x,2); if (!dpos) return 0;
+        dpos = dns_packet_getname(data,dlen,dpos,&d1); if (!dpos) return 0;
+        mxttl = ttl;
+        i = dns_random(mxnum + 1);
+        if (i < 8) {
+          if ((i < mxnum) && (mxnum < 8)) {
+            byte_copy(mxdist[mxnum],2,mxdist[i]);
+            swapnames(&mxname[mxnum],&mxname[i]);
+          }
+          byte_copy(mxdist[i],2,x);
+          swapnames(&mxname[i],&d1);
+        }
+        if (mxnum < 1000000) ++mxnum;
+        continue;
+      }
       if (!response_rstart(q,type,ttl)) return 0;
       if (byte_equal(type,2,DNS_T_NS) ||
byte_equal(type,2,DNS_T_CNAME) || byte_equal(type,2,DNS_T_PTR)) {
 	if (!doname()) return 0;
       }
-      else if (byte_equal(type,2,DNS_T_MX)) {
-	if (!dobytes(2)) return 0;
-	if (!doname()) return 0;
-      }
       else if (byte_equal(type,2,DNS_T_SOA)) {
 	if (!doname()) return 0;
 	if (!doname()) return 0;
@@ -195,6 +220,13 @@
 	if (!response_addbytes(addr[i],4)) return 0;
 	response_rfinish(RESPONSE_ANSWER);
       }
+    for (i = 0;i < mxnum;++i)
+      if (i < 8) {
+        if (!response_rstart(q,DNS_T_MX,mxttl)) return 0;
+        if (!response_addbytes(mxdist[i],2)) return 0;
+        if (!response_addname(mxname[i])) return 0;
+        response_rfinish(RESPONSE_ANSWER);
+      }

     if (flagfound) break;
     if (wild == control) break;