X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=secnet.git;a=blobdiff_plain;f=udp.c;h=bb82026c144d0df1f56f9f52e9401dd2fae91691;hp=bbf8c64163dbd8815001493c90a12d8f8cac30c9;hb=4fb0f88d53fc60395a4a87b7a9ca1245ba033ee7;hpb=51b259535294bb46757a040596ab052e53f29483

diff --git a/udp.c b/udp.c
index bbf8c64..bb82026 100644
--- a/udp.c
+++ b/udp.c
@@ -19,8 +19,10 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include "util.h"
+#include "magic.h"
 #include "unaligned.h"
 #include "ipaddr.h"
+#include "magic.h"
 
 static beforepoll_fn udp_beforepoll;
 static afterpoll_fn udp_afterpoll;
@@ -101,8 +103,10 @@ static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
 	    fromlen=sizeof(from);
 	    BUF_ASSERT_FREE(st->rbuf);
 	    BUF_ALLOC(st->rbuf,"udp_afterpoll");
-	    rv=recvfrom(st->fd, st->rbuf->start, st->rbuf->len, 0,
-			(struct sockaddr *)&from, &fromlen);
+	    buffer_init(st->rbuf,calculate_max_start_pad());
+	    rv=recvfrom(st->fd, st->rbuf->start,
+			buf_remaining_space(st->rbuf),
+			0, (struct sockaddr *)&from, &fromlen);
 	    if (rv>0) {
 		st->rbuf->size=rv;
 		if (st->use_proxy) {
@@ -120,29 +124,28 @@ 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);
@@ -193,12 +196,13 @@ static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
     uint8_t *sa;
 
     if (st->use_proxy) {
-	sa=buf->start-8;
+	sa=buf_prepend(buf,8);
 	memcpy(sa,&dest->sin.sin_addr,4);
 	memset(sa+4,0,4);
 	memcpy(sa+6,&dest->sin.sin_port,2);
 	sendto(st->fd,sa,buf->size+8,0,(struct sockaddr *)&st->proxy,
 	       sizeof(st->proxy));
+	buf_unprepend(buf,8);
     } else {
 	sendto(st->fd, buf->start, buf->size, 0,
 	       (struct sockaddr *)&dest->sin, sizeof(dest->sin));
@@ -220,10 +224,7 @@ static void udp_phase_hook(void *sst, uint32_t new_phase)
 	fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
 		     st->loc.file,st->loc.line);
     }
-    if (fcntl(st->fd, F_SETFD, FD_CLOEXEC)==-1) {
-	fatal_perror("udp (%s:%d): fcntl(set FD_CLOEXEC)",
-		     st->loc.file,st->loc.line);
-    }
+    setcloexec(st->fd);
 
     FILLZERO(addr);
     addr.sin_family=AF_INET;
@@ -288,8 +289,6 @@ static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
     st->cl.apply=NULL;
     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;
@@ -324,9 +323,10 @@ static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
 	    cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
 	}
 	st->proxy.sin_port=htons(i->data.number);
-	st->ops.min_start_pad=8;
     }
 
+    update_max_start_pad(&comm_max_start_pad, st->use_proxy ? 8 : 0);
+
     add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
 
     return new_closure(&st->cl);