chiark / gitweb /
site: transport peers: Formalise interface to transport peers
[secnet.git] / site.c
diff --git a/site.c b/site.c
index b04f3b340b91f9e90057636c9f6ba1b347d4f850..297bb749e19df934538b868d8304c29661d399b1 100644 (file)
--- a/site.c
+++ b/site.c
@@ -198,18 +198,35 @@ typedef struct {
     transport_peer peers[MAX_MOBILE_PEERS_MAX];
 } transport_peers;
 
+/* Basic operations on transport peer address sets */
 static void transport_peers_clear(struct site *st, transport_peers *peers);
 static int transport_peers_valid(transport_peers *peers);
 static void transport_peers_copy(struct site *st, transport_peers *dst,
                                 const transport_peers *src);
 
+/* Record address of incoming setup packet; resp. data packet. */
 static void transport_setup_msgok(struct site *st, const struct comm_addr *a);
 static void transport_data_msgok(struct site *st, const struct comm_addr *a);
+
+/* Initialise the setup addresses.  Called before we send the first
+ * packet in a key exchange.  If we are the initiator, as a result of
+ * resolve completing (or being determined not to be relevant) or an
+ * incoming PROD; if we are the responder, as a result of the MSG1. */
 static bool_t transport_compute_setupinit_peers(struct site *st,
         const struct comm_addr *configured_addr /* 0 if none or not found */,
-        const struct comm_addr *prod_hint_addr /* 0 if none */);
-static void transport_record_peer(struct site *st, transport_peers *peers,
-                                 const struct comm_addr *addr, const char *m);
+        const struct comm_addr *incoming_packet_addr /* 0 if none */);
+
+/* Called if we are the responder in a key setup, when the resolve
+ * completes.  transport_compute_setupinit_peers will hvae been called
+ * earlier.  If _complete is called, we are still doing the key setup
+ * (and we should use the new values for both the rest of the key
+ * setup and the ongoing data exchange); if _tardy is called, the key
+ * setup is done (either completed or not) and only the data peers are
+ * relevant */
+static void transport_resolve_complete(struct site *st,
+                                      const struct comm_addr *a);
+static void transport_resolve_complete_tardy(struct site *st,
+                                            const struct comm_addr *ca_use);
 
 static void transport_xmit(struct site *st, transport_peers *peers,
                           struct buffer_if *buf, bool_t candebug);
@@ -545,9 +562,9 @@ static bool_t generate_msg(struct site *st, uint32_t type, cstring_t what)
     append_string_xinfo_done(&st->buffer,&xia);
 
     buf_append_string(&st->buffer,st->remotename);
-    memcpy(buf_append(&st->buffer,NONCELEN),st->localN,NONCELEN);
+    BUF_ADD_OBJ(append,&st->buffer,st->localN);
     if (type==LABEL_MSG1) return True;
-    memcpy(buf_append(&st->buffer,NONCELEN),st->remoteN,NONCELEN);
+    BUF_ADD_OBJ(append,&st->buffer,st->remoteN);
     if (type==LABEL_MSG2) return True;
 
     if (hacky_par_mid_failnow()) return False;
@@ -699,7 +716,6 @@ static bool_t process_msg1(struct site *st, struct buffer_if *msg1,
        process an incoming MSG1, and that the MSG1 has correct values
        of A and B. */
 
-    transport_record_peer(st,&st->setup_peers,src,"msg1");
     st->setup_session_id=m->source;
     st->remote_capabilities=m->remote_capabilities;
     memcpy(st->remoteN,m->nR,NONCELEN);
@@ -1150,10 +1166,6 @@ static void site_resolve_callback(void *sst, struct in_addr *address)
 
     st->resolving=False;
 
-    if (st->state!=SITE_RESOLVE) {
-       slog(st,LOG_UNEXPECTED,"site_resolve_callback called unexpectedly");
-       return;
-    }
     if (address) {
        FILLZERO(ca_buf);
        ca_buf.comm=st->comms[0];
@@ -1161,16 +1173,65 @@ static void site_resolve_callback(void *sst, struct in_addr *address)
        ca_buf.sin.sin_port=htons(st->remoteport);
        ca_buf.sin.sin_addr=*address;
        ca_use=&ca_buf;
+       slog(st,LOG_STATE,"resolution of %s completed: %s",
+            st->address, comm_addr_to_string(ca_use));;
     } else {
        slog(st,LOG_ERROR,"resolution of %s failed",st->address);
        ca_use=0;
     }
-    if (transport_compute_setupinit_peers(st,ca_use,0)) {
-       enter_new_state(st,SITE_SENTMSG1);
-    } else {
-       /* Can't figure out who to try to to talk to */
-       slog(st,LOG_SETUP_INIT,"key exchange failed: cannot find peer address");
-       enter_state_run(st);
+
+    switch (st->state) {
+    case SITE_RESOLVE:
+        if (transport_compute_setupinit_peers(st,ca_use,0)) {
+           enter_new_state(st,SITE_SENTMSG1);
+       } else {
+           /* Can't figure out who to try to to talk to */
+           slog(st,LOG_SETUP_INIT,
+                "key exchange failed: cannot find peer address");
+           enter_state_run(st);
+       }
+       break;
+    case SITE_SENTMSG1: case SITE_SENTMSG2:
+    case SITE_SENTMSG3: case SITE_SENTMSG4:
+    case SITE_SENTMSG5:
+       if (ca_use) {
+           /* We start using the address immediately for data too.
+            * It's best to store it in st->peers now because we might
+            * go via SENTMSG5, WAIT, and a MSG0, straight into using
+            * the new key (without updating the data peer addrs). */
+           transport_resolve_complete(st,ca_use);
+       } else if (st->local_mobile) {
+           /* We can't let this rest because we may have a peer
+            * address which will break in the future. */
+           slog(st,LOG_SETUP_INIT,"resolution of %s failed: "
+                "abandoning key exchange",st->address);
+           enter_state_wait(st);
+       } else {
+           slog(st,LOG_SETUP_INIT,"resolution of %s failed: "
+                " continuing to use source address of peer's packets"
+                " for key exchange and ultimately data",
+                st->address);
+       }
+       break;
+    case SITE_RUN:
+       if (ca_use) {
+           slog(st,LOG_SETUP_INIT,"resolution of %s completed tardily,"
+                " updating peer address(es)",st->address);
+           transport_resolve_complete_tardy(st,ca_use);
+       } else if (st->local_mobile) {
+           /* Not very good.  We should queue (another) renegotiation
+            * so that we can update the peer address. */
+           st->key_renegotiate_time=st->now+st->wait_timeout;
+       } else {
+           slog(st,LOG_SETUP_INIT,"resolution of %s failed: "
+                " continuing to use source address of peer's packets",
+                st->address);
+       }
+       break;
+    case SITE_WAIT:
+    case SITE_STOP:
+       /* oh well */
+       break;
     }
 }
 
@@ -1280,8 +1341,8 @@ static void enter_state_run(struct site *st)
 
     st->setup_session_id=0;
     transport_peers_clear(st,&st->setup_peers);
-    memset(st->localN,0,NONCELEN);
-    memset(st->remoteN,0,NONCELEN);
+    FILLZERO(st->localN);
+    FILLZERO(st->remoteN);
     dispose_transform(&st->new_transform);
     memset(st->dhsecret,0,st->dh->len);
     memset(st->sharedsecret,0,st->sharedsecretlen);
@@ -1295,6 +1356,8 @@ static bool_t ensure_resolving(struct site *st)
     if (st->resolving)
         return True;
 
+    assert(st->address);
+
     /* resolver->request might reentrantly call site_resolve_callback
      * which will clear st->resolving, so we need to set it beforehand
      * rather than afterwards; also, it might return False, in which
@@ -1580,9 +1643,14 @@ static bool_t site_incoming(void *sst, struct buffer_if *buf,
        if (st->state==SITE_RUN || st->state==SITE_RESOLVE ||
            st->state==SITE_WAIT) {
            /* We should definitely process it */
+           transport_compute_setupinit_peers(st,0,source);
            if (process_msg1(st,buf,source,&named_msg)) {
                slog(st,LOG_SETUP_INIT,"key setup initiated by peer");
-               enter_new_state(st,SITE_SENTMSG2);
+               bool_t entered=enter_new_state(st,SITE_SENTMSG2);
+               if (entered && st->address && st->local_mobile)
+                   /* We must do this as the very last thing, because
+                      the resolver callback might reenter us. */
+                   ensure_resolving(st);
            } else {
                slog(st,LOG_ERROR,"failed to process incoming msg1");
            }
@@ -1602,6 +1670,7 @@ static bool_t site_incoming(void *sst, struct buffer_if *buf,
                     "priority => use incoming msg1");
                if (process_msg1(st,buf,source,&named_msg)) {
                    BUF_FREE(&st->buffer); /* Free our old message 1 */
+                   transport_setup_msgok(st,source);
                    enter_new_state(st,SITE_SENTMSG2);
                } else {
                    slog(st,LOG_ERROR,"failed to process an incoming "
@@ -1640,7 +1709,7 @@ static bool_t site_incoming(void *sst, struct buffer_if *buf,
               because our peer's forgotten the key */
            if (get_uint32(buf->start+4)==st->current.remote_session_id) {
                bool_t initiated;
-               initiated = initiate_key_setup(st,"received a NAK",0);
+               initiated = initiate_key_setup(st,"received a NAK",source);
                if (!initiated) generate_send_prod(st,source);
            } else {
                slog(st,LOG_SEC,"bad incoming NAK");
@@ -2038,16 +2107,16 @@ static void transport_record_peer(struct site *st, transport_peers *peers,
 
 static bool_t transport_compute_setupinit_peers(struct site *st,
         const struct comm_addr *configured_addr /* 0 if none or not found */,
-        const struct comm_addr *prod_hint_addr /* 0 if none */) {
+        const struct comm_addr *incoming_packet_addr /* 0 if none */) {
 
-    if (!configured_addr && !prod_hint_addr &&
+    if (!configured_addr && !incoming_packet_addr &&
        !transport_peers_valid(&st->peers))
        return False;
 
     slog(st,LOG_SETUP_INIT,
         "using:%s%s %d old peer address(es)",
         configured_addr ? " configured address;" : "",
-        prod_hint_addr ? " PROD hint address;" : "",
+        incoming_packet_addr ? " incoming packet address;" : "",
         st->peers.npeers);
 
     /* Non-mobile peers have st->peers.npeers==0 or ==1, since they
@@ -2058,8 +2127,9 @@ static bool_t transport_compute_setupinit_peers(struct site *st,
 
     transport_peers_copy(st,&st->setup_peers,&st->peers);
 
-    if (prod_hint_addr)
-       transport_record_peer(st,&st->setup_peers,prod_hint_addr,"prod");
+    if (incoming_packet_addr)
+       transport_record_peer(st,&st->setup_peers,incoming_packet_addr,
+                             "incoming");
 
     if (configured_addr)
        transport_record_peer(st,&st->setup_peers,configured_addr,"setupinit");
@@ -2092,6 +2162,17 @@ static void transport_peers_copy(struct site *st, transport_peers *dst,
                          src->npeers, &src->peers->addr, sizeof(*src->peers));
 }
 
+static void transport_resolve_complete(struct site *st,
+                                      const struct comm_addr *ca_use) {
+    transport_record_peer(st,&st->peers,ca_use,"resolved data");
+    transport_record_peer(st,&st->setup_peers,ca_use,"resolved setup");
+}
+
+static void transport_resolve_complete_tardy(struct site *st,
+                                            const struct comm_addr *ca_use) {
+    transport_record_peer(st,&st->peers,ca_use,"resolved tardily");
+}
+
 void transport_xmit(struct site *st, transport_peers *peers,
                    struct buffer_if *buf, bool_t candebug) {
     int slot;