(Closes #64)
git-svn-id: file:///home/lennart/svn/public/avahi/trunk@1345 
941a03a8-eaeb-0310-b9a0-
b1bbd8fe43fe
 
     struct type_info type_info;
     
     AVAHI_WARN_LINKAGE;
-    
-    assert(ret_sdref);
+
+    if (!ret_sdref)
+        return kDNSServiceErr_BadParam;
+
+    *ret_sdref = NULL;
+
     assert(regtype);
-    assert(callback);
 
     if (interface == kDNSServiceInterfaceIndexLocalOnly || flags != 0) {
         AVAHI_WARN_UNSUPPORTED;
 
     AVAHI_WARN_LINKAGE;
 
-    assert(ret_sdref);
-    assert(regtype);
+    if (!ret_sdref)
+        return kDNSServiceErr_BadParam;
+
+    *ret_sdref = NULL;
+    
+    if (!regtype)
+           return kDNSServiceErr_BadParam;
+       
     assert(txtRecord || txtLen == 0);
 
     if (interface == kDNSServiceInterfaceIndexLocalOnly || flags) {