ospfd: run DR election prior to LSA regeneration

The results from DR election are used when constructing router-LSAs.
E.g. they are used to determine whether a broadcast interface should
be added with a link type of stub interface or transit interface.

Therefore, we should run DR election prior before regenerating LSAs.

Before commit c363d3861b5384a31465a72ddc3b0f6ff007a95a the DR election
was called synchronously prior to router-LSA regeneration which was run
asynchronously.

This fixes bug #761 on the Quagga bugzilla.

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
Acked-by: Feng Lu <lu.feng@6wind.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
ospfd: don't allow to set network type on loopback interfaces

OSPFd only allocates some stub information for loopback interfaces.
This causes a crash when the interface state machine is started on
that interface by configuring a different network type.

It doesn't make much sense to configure the network type of a loopback
interface, therefore, just forbid it.

See also bugzilla #670.

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
ospfd: check the LS-Ack's recentness instead of only comparing the #seq

ISSUE:

RTA(DR)-----(BackupDR)RTB

RTA advertises a new LSA to RTB, and then flushes the LSA (with setting
the age of the LSA to MaxAge) within 1 second. Then the LSA is deleted
from RTA, while it still exists on RTB with non-MaxAge and can not be
flushed any more.

FIX:

The reason can be explained in below:

a) RTA -- new LSA, #seq=1 --> RTB (RTB will send the delayed Ack in 1s)
b) RTA -- MaxAge LSA, #seq=1 --> RTB (RTB discards it for the MIN_LS_ARRIVAL)
c) RTA <-- Ack for the new LSA, #seq=1 -- RTB (RTA accepts it)

In the step c), ospf_ls_ack() compares the #seq of the entry in the LS-Ack
with that of local MaxAge LSA. The #seq of the two entries are same. So
the Ack is accepted and the LSA is removed from the retransmit-list (while
it should not).

In RFC2328, section  13.7.  Receiving link state acknowledgments:

o   If the acknowledgment is for the same instance that is  <==
    contained on the list, remove the item from the list and
    examine the next acknowledgment.  Otherwise:

where "same instance" does not mean the same #seq. We must call
ospf_lsa_more_recent() to check whether the two instances are same.

Signed-off-by: Feng Lu <lu.feng@6wind.com>
Signed-off-by: Christian Franke <chris@opensourcerouting.org>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
ospfd: fix a reference counting issue introduced by commit 4de8bf0011

Commit 4de8bf0011 added a return statement to a loop iterating over a
route_table. That loop uses route_top/route_next.

As commit 4de8bf0011 failed to add a route_node_unlock before the
return statement, a reference is leaked when this codepath is taken.

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
Acked-by: Feng Lu <lu.feng@6wind.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
ospfd: clarify indentation and comments in ospf_lsa_maxage_delete

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
Acked-by: Feng Lu <lu.feng@6wind.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
ospfd: For an ABR, ensure the right LSID is MaxAge'd

PROBLEM:

Accurate garbage collection of maxage LSAs. The global OSPF structure has
a maxage_lsa tree - the key to the tree is <ls-id, adv-router> tuple. Suppose
the ABR has multiple areas and has originated some intra-area LSAs. The
key for all those LSAs is the same. The code then ends up in a state where
all but the first LSA do not get cleaned up from the areas' LSDB. A subsequent
event would readvertise those LSAs.

PATCH:

Since the LSA is going to stick around till it actually gets cleaned up by
the maxage_walker, make the LSA pointer as the key. Each distinct LSA that
gets maxage'd then gets added to the tree and will get cleaned up correctly.

Signed-off-by: Pradosh Mohapatra <pmohapat@cumulusnetworks.com>
[CF: Use CHAR_BIT; use uintptr_t; use sizeof(field) instead of sizeof(type)]
Signed-off-by: Christian Franke <chris@opensourcerouting.org>
[DL: this must remain a temporary fix! needs to be redone after 0.99.23]
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
ospfd: add debug messages for router lsa-generation

Add log messages to lsa_link_broadcast_set so it becomes more
apparent why a particular broadcast interface was added as
transit or stub interface.

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
Acked-by: Feng Lu <lu.feng@6wind.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>