isisd: fix crash on "no router isis" (BZ#536)

The crash is due to threads accessing data that gets destroyed
during the removal of the configuration.

* isis_circuit.c: Destroy adjacencies to stop adjacency expiry thread.
  Stop PSNP threads.
* isisd.c: Change state of circuit back to INIT and reassign the
  circuit structure to isis->init_circ_list rather than destroying
  the circuit data structure. Stop SPF threads. Stop LSP generation
  threads.
* isisd.h: Add pointers to LSP threads into area structure in order to
  stop them in isisd.c
* isis_lsp.c: Store pointer to LSP thread in area structure.
* isis_pdu.c: Stop PDU generation for a circuit with a removed area.
* isis_pfpacket.c: Stop processing received PDUs for a circuit with a
  removed area.

1 files changed, 8 insertions, 0 deletions

diff --git a/isisd/isis_pdu.c b/isisd/isis_pdu.c
index 8219e837..34e4b03d 100644
--- a/isisd/isis_pdu.c
+++ b/isisd/isis_pdu.c
@@ -1781,6 +1781,9 @@ isis_receive (struct thread *thread)
   circuit = THREAD_ARG (thread);
   assert (circuit);
 
+  if (!circuit->area)
+    return ISIS_OK;
+
   if (circuit->rcv_stream == NULL)
     circuit->rcv_stream = stream_new (ISO_MTU (circuit));
   else
@@ -2088,6 +2091,11 @@ send_lan_l2_hello (struct thread *thread)
 
   circuit = THREAD_ARG (thread);
   assert (circuit);
+
+  if (!circuit->area) {
+    return ISIS_OK;
+  }
+
   circuit->u.bc.t_send_lan_hello[1] = NULL;
 
   if (circuit->u.bc.run_dr_elect[1])