X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=secnet.git;a=blobdiff_plain;f=udp.c;h=483ed375e7ae876bf34a222250c90063cabc57c2;hp=77be5b1786f7868ad3691b24be8fa35c3936695d;hb=fcad4b0b370b9fc232db98895fbfe22177436433;hpb=136740e64e3fedcd725490c2f80d0906de515197

diff --git a/udp.c b/udp.c
index 77be5b1..483ed37 100644
--- a/udp.c
+++ b/udp.c
@@ -121,29 +121,28 @@ static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
 		    buf_unprepend(st->rbuf,2);
 		    memcpy(&from.sin_port,buf_unprepend(st->rbuf,2),2);
 		}
+		struct comm_addr ca;
+		FILLZERO(ca);
+		ca.comm=&st->ops;
+		ca.sin=from;
 		done=False;
 		for (n=st->notify; n; n=n->next) {
-		    struct comm_addr ca;
-		    FILLZERO(ca);
-		    ca.comm=&st->ops;
-		    ca.sin=from;
 		    if (n->fn(n->state, st->rbuf, &ca)) {
 			done=True;
 			break;
 		    }
 		}
 		if (!done) {
-		    uint32_t source,dest;
-		    /* Manufacture and send NAK packet */
-		    source=get_uint32(st->rbuf->start); /* Us */
-		    dest=get_uint32(st->rbuf->start+4); /* Them */
-		    Message(M_INFO,"udp (port %d): sending NAK\n",st->port);
-		    buffer_init(st->rbuf,0);
-		    buf_append_uint32(st->rbuf,dest);
-		    buf_append_uint32(st->rbuf,source);
-		    buf_append_uint32(st->rbuf,LABEL_NAK);
-		    sendto(st->fd, st->rbuf->start, st->rbuf->size, 0,
-			   (struct sockaddr *)&from, sizeof(from));
+		    uint32_t msgtype;
+		    if (st->rbuf->size>12 /* prevents traffic amplification */
+			&& ((msgtype=get_uint32(st->rbuf->start+8))
+			    != LABEL_NAK)) {
+			uint32_t source,dest;
+			/* Manufacture and send NAK packet */
+			source=get_uint32(st->rbuf->start); /* Us */
+			dest=get_uint32(st->rbuf->start+4); /* Them */
+			send_nak(&ca,source,dest,msgtype,st->rbuf,"unwanted");
+		    }
 		    BUF_FREE(st->rbuf);
 		}
 		BUF_ASSERT_FREE(st->rbuf);