udp.c: Do not send NAKs in response to NAKs

[secnet.git] / udp.c

diff --git a/udp.c b/udp.c
index 8ec8581f6c28aa1eaa89f002f055feb5f7167427..c83e618fb6ca91876dcb1307c2bac516ba35a06a 100644 (file)
--- a/udp.c
+++ b/udp.c
@@ -16,9 +16,12 @@
 #include <errno.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
 #include "util.h"
 #include "unaligned.h"
 #include "ipaddr.h"
+#include "magic.h"
 
 static beforepoll_fn udp_beforepoll;
 static afterpoll_fn udp_afterpoll;
@@ -46,6 +49,30 @@ 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)
 {
@@ -106,17 +133,26 @@ static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
                    }
                }
                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 */
+                       Message(M_INFO,"udp (port %d, peer %s):"
+                               " %08"PRIx32"<-%08"PRIx32": %08"PRIx32":"
+                               " unwanted/incorrect, sending NAK\n",
+                               st->port, saddr_to_string(&from),
+                               dest, source, msgtype);
+                       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));
+                   }
                    BUF_FREE(st->rbuf);
                }
                BUF_ASSERT_FREE(st->rbuf);
@@ -215,8 +251,8 @@ 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;
@@ -267,6 +303,7 @@ static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
     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;