[Project] Rdns: Send truncated replies via TCP

diff --git a/contrib/librdns/dns_private.h b/contrib/librdns/dns_private.h
index 137b317e82a761a3029f55881589e72086d11d9d..a5eebfd97b9b9de7dd3a35141bfbc3d67057b2f3 100644 (file)
--- a/contrib/librdns/dns_private.h
+++ b/contrib/librdns/dns_private.h
@@ -134,7 +134,6 @@ struct rdns_request {
        void *curve_plugin_data;
 #endif
 
-       UT_hash_handle hh;
        ref_entry_t ref;
 };
 

diff --git a/contrib/librdns/resolver.c b/contrib/librdns/resolver.c
index a576135db0fdc4753570b3678c36039d306d298f..ff1acf789bb9860cc4638f810ec347c91fd04650 100644 (file)
--- a/contrib/librdns/resolver.c
+++ b/contrib/librdns/resolver.c
@@ -437,6 +437,55 @@ rdns_process_tcp_connect (int fd, struct rdns_io_channel *ioc)
        }
 }
 
+static bool
+rdns_reschedule_req_over_tcp (struct rdns_request *req, struct rdns_server *serv)
+{
+       struct rdns_resolver *resolver;
+       struct rdns_io_channel *old_ioc = req->io,
+                       *ioc = serv->tcp_io_channels[ottery_rand_uint32 () % serv->tcp_io_cnt];
+
+       resolver = req->resolver;
+
+       if (ioc != NULL) {
+               if (!IS_CHANNEL_CONNECTED(ioc)) {
+                       if (!rdns_ioc_tcp_connect(ioc)) {
+                               return false;
+                       }
+               }
+
+               struct rdns_tcp_output_chain *oc;
+
+               oc = calloc(1, sizeof(*oc));
+
+               if (oc == NULL) {
+                       rdns_err("failed to allocate output buffer for TCP ioc: %s",
+                                       strerror(errno));
+                       return false;
+               }
+
+               oc->req = req;
+               oc->next_write_size = req->packet_len;
+
+               DL_APPEND(ioc->tcp->output_chain, oc);
+
+               if (ioc->tcp->async_write == NULL) {
+                       ioc->tcp->async_write = resolver->async->add_write (
+                                       resolver->async->data,
+                                       ioc->sock, ioc);
+               }
+
+               req->state = RDNS_REQUEST_TCP;
+               /* Switch IO channel from UDP to TCP */
+               req->io = ioc;
+               REF_RETAIN(ioc);
+               REF_RELEASE(old_ioc);
+
+               return true;
+       }
+
+       return false;
+}
+
 static void
 rdns_process_udp_read (int fd, struct rdns_io_channel *ioc)
 {
@@ -475,9 +524,24 @@ rdns_process_udp_read (int fd, struct rdns_io_channel *ioc)
                        }
 
                        rdns_request_unschedule (req);
-                       req->state = RDNS_REQUEST_REPLIED;
-                       req->func (rep, req->arg);
-                       REF_RELEASE (req);
+
+                       if (!(rep->flags & RDNS_TRUNCATED)) {
+                               req->state = RDNS_REQUEST_REPLIED;
+                               req->func(rep, req->arg);
+                               REF_RELEASE (req);
+                       }
+                       else {
+                               rdns_debug("truncated UDP reply for %s", req->requested_names[0].name);
+                               if (req->io->srv->tcp_io_cnt > 0) {
+                                       /* Reschedule via TCP */
+                                       if (!rdns_reschedule_req_over_tcp (req, req->io->srv)) {
+                                               /* Use truncated reply as we have no other options */
+                                               req->state = RDNS_REQUEST_REPLIED;
+                                               req->func(rep, req->arg);
+                                               REF_RELEASE (req);
+                                       }
+                               }
+                       }
                }
        }
        else {