X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=secnet.git;a=blobdiff_plain;f=udp.c;h=12fcfe8c6ec6edb5c0904c1952d36b00c8ddd94f;hp=bbf8c64163dbd8815001493c90a12d8f8cac30c9;hb=45a1170652384baf744a5e61d576af534c7b8b14;hpb=51b259535294bb46757a040596ab052e53f29483

diff --git a/udp.c b/udp.c
index bbf8c64..12fcfe8 100644
--- a/udp.c
+++ b/udp.c
@@ -21,6 +21,7 @@
 #include "util.h"
 #include "unaligned.h"
 #include "ipaddr.h"
+#include "magic.h"
 
 static beforepoll_fn udp_beforepoll;
 static afterpoll_fn udp_afterpoll;
@@ -120,29 +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,0); /* NAK is msg type 0 */
-		    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);
@@ -289,7 +289,6 @@ static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
     st->cl.interface=&st->ops;
     st->ops.st=st;
     st->ops.min_start_pad=0;
-    st->ops.min_end_pad=0;
     st->ops.request_notify=request_notify;
     st->ops.release_notify=release_notify;
     st->ops.sendmsg=udp_sendmsg;