2 files changed, 21 insertions, 0 deletions
diff --git a/dnscache.c b/dnscache.c
index abcba69..2366ecc 100644
--- a/dnscache.c
+++ b/dnscache.c
@@ -72,11 +72,15 @@ static struct udpclient {
 } u[MAXUDP];
 int uactive = 0;
 
+#define MAXSOA 20
+int soaactive = 0;
+
 void u_drop(int j)
 {
   if (!u[j].active) return;
   log_querydrop(&u[j].active);
   u[j].active = 0; --uactive;
+  if (byte_equal(u[j].q.type,2,DNS_T_SOA)) --soaactive;
 }
 
 void u_respond(int j)
@@ -87,6 +91,7 @@ void u_respond(int j)
   socket_send6(udp53,response,response_len,u[j].ip,u[j].port,u[j].scope_id);
   log_querydone(&u[j].active,response_len);
   u[j].active = 0; --uactive;
+  if (byte_equal(u[j].q.type,2,DNS_T_SOA)) --soaactive;
 }
 
 void u_new(void)
@@ -125,6 +130,16 @@ void u_new(void)
 
   x->active = ++numqueries; ++uactive;
   log_query(&x->active,x->ip,x->port,x->id,q,qtype);
+
+  if (byte_equal(qtype,2,DNS_T_SOA)) {
+    if (soaactive >= MAXSOA) {
+      log_querydropmaxsoa(&x->active);
+      x->active = 0; --uactive;
+      return;
+    }
+    ++soaactive;
+  }
+
   switch(query_start(&x->q,q,qtype,qclass,myipoutgoing,interface)) {
     case -1:
       u_drop(j);
diff --git a/log.c b/log.c
index df465e2..a651607 100644
--- a/log.c
+++ b/log.c
@@ -118,6 +118,12 @@ void log_querydrop(uint64 *qnum)
   line();
 }
 
+void log_querydropmaxsoa(uint64 *qnum)
+{
+  string("drop "); number(*qnum); space(); string("maxsoa");
+  line();
+}
+
 void log_tcpopen(const char client[16],unsigned int port)
 {
   string("tcpopen ");