X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=secnet.git;a=blobdiff_plain;f=udp.c;h=97b92a6017b81677b9c50f2be3db6ee282d1fde2;hp=8ec8581f6c28aa1eaa89f002f055feb5f7167427;hb=34d3bf4cdcb2d2938c3b92573f66815e4d9392ac;hpb=a15faeb2b12e9cc0e3d1352cf4c233fc61c51c1c

diff --git a/udp.c b/udp.c
index 8ec8581..97b92a6 100644
--- a/udp.c
+++ b/udp.c
@@ -16,9 +16,13 @@
 #include <errno.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
+#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;
@@ -46,6 +50,30 @@ struct udp {
     struct sockaddr_in proxy;
 };
 
+static const char *saddr_to_string(const struct sockaddr_in *sin) {
+    static char bufs[2][100];
+    static int b;
+
+    b ^= 1;
+    snprintf(bufs[b], sizeof(bufs[b]), "[%s]:%d",
+	     inet_ntoa(sin->sin_addr),
+	     ntohs(sin->sin_port));
+    return bufs[b];
+}
+
+static const char *addr_to_string(void *commst, const struct comm_addr *ca) {
+    struct udp *st=commst;
+    static char sbuf[100];
+
+    struct sockaddr_in la;
+    la.sin_addr.s_addr=htonl(st->addr);
+    la.sin_port=htons(st->port);
+
+    snprintf(sbuf, sizeof(sbuf), "udp:%s-%s",
+	     saddr_to_string(&la), saddr_to_string(&ca->sin));
+    return sbuf;
+}
+
 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
 			  int *timeout_io)
 {
@@ -75,6 +103,7 @@ 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");
+	    buffer_init(st->rbuf,calculate_max_start_pad());
 	    rv=recvfrom(st->fd, st->rbuf->start, st->rbuf->len, 0,
 			(struct sockaddr *)&from, &fromlen);
 	    if (rv>0) {
@@ -94,29 +123,28 @@ 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);
@@ -167,12 +195,13 @@ 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));
@@ -215,8 +244,8 @@ static void udp_phase_hook(void *sst, uint32_t new_phase)
 	}
 	if (c==0) {
 	    char *argv[4], addrstr[9], portstr[5];
-	    sprintf(addrstr,"%08lX",(long)st->addr);
-	    sprintf(portstr,"%04X",st->port);
+	    sprintf(addrstr,"%08lX",(long)addr.sin_addr.s_addr);
+	    sprintf(portstr,"%04X",addr.sin_port);
 	    argv[0]=st->authbind;
 	    argv[1]=addrstr;
 	    argv[2]=portstr;
@@ -262,11 +291,10 @@ 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;
+    st->ops.addr_to_string=addr_to_string;
     st->port=0;
     st->use_proxy=False;
 
@@ -297,9 +325,10 @@ 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);