[bgpd] Stability fixes including bugs 397, 492

[bgpd] Stability fixes including bugs 397, 492

I've spent the last several weeks working on stability fixes to bgpd.
These patches fix all of the numerous crashes, assertion failures, memory
leaks and memory stomping I could find.  Valgrind was used extensively.

Added new function bgp_exit() to help catch problems.  If "debug bgp" is
configured and bgpd exits with status of 0, statistics on remaining
lib/memory.c allocations are printed to stderr.  It is my hope that other
developers will use this to stay on top of memory issues.

Example questionable exit:

  bgpd: memstats: Current memory utilization in module LIB:
  bgpd: memstats:  Link List                     :          6
  bgpd: memstats:  Link Node                     :          5
  bgpd: memstats:  Hash                          :          8
  bgpd: memstats:  Hash Bucket                   :          2
  bgpd: memstats:  Hash Index                    :          8
  bgpd: memstats:  Work queue                    :          3
  bgpd: memstats:  Work queue item               :          2
  bgpd: memstats:  Work queue name string        :          3
  bgpd: memstats: Current memory utilization in module BGP:
  bgpd: memstats:  BGP instance                  :          1
  bgpd: memstats:  BGP peer                      :          1
  bgpd: memstats:  BGP peer hostname             :          1
  bgpd: memstats:  BGP attribute                 :          1
  bgpd: memstats:  BGP extra attributes          :          1
  bgpd: memstats:  BGP aspath                    :          1
  bgpd: memstats:  BGP aspath str                :          1
  bgpd: memstats:  BGP table                     :         24
  bgpd: memstats:  BGP node                      :          1
  bgpd: memstats:  BGP route                     :          1
  bgpd: memstats:  BGP synchronise               :          8
  bgpd: memstats:  BGP Process queue             :          1
  bgpd: memstats:  BGP node clear queue          :          1
  bgpd: memstats: NOTE: If configuration exists, utilization may be expected.

Example clean exit:

  bgpd: memstats: No remaining tracked memory utilization.

This patch fixes bug #397: "Invalid free in bgp_announce_check()".

This patch fixes bug #492: "SIGBUS in bgpd/bgp_route.c:
bgp_clear_route_node()".

My apologies for not separating out these changes into individual patches.
The complexity of doing so boggled what is left of my brain.  I hope this
is all still useful to the community.

This code has been production tested, in non-route-server-client mode, on
a linux 32-bit box and a 64-bit box.

Release/reset functions, used by bgp_exit(), added to:

  bgpd/bgp_attr.c,h
  bgpd/bgp_community.c,h
  bgpd/bgp_dump.c,h
  bgpd/bgp_ecommunity.c,h
  bgpd/bgp_filter.c,h
  bgpd/bgp_nexthop.c,h
  bgpd/bgp_route.c,h
  lib/routemap.c,h

File by file analysis:

* bgpd/bgp_aspath.c: Prevent re-use of ashash after it is released.

* bgpd/bgp_attr.c: #if removed uncalled cluster_dup().

* bgpd/bgp_clist.c,h: Allow community_list_terminate() to be called from
  bgp_exit().

* bgpd/bgp_filter.c: Fix aslist->name use without allocation check, and
  also fix memory leak.

* bgpd/bgp_main.c: Created bgp_exit() exit routine.  This function frees
  allocations made as part of bgpd initialization and, to some extent,
  configuration.  If "debug bgp" is configured, memory stats are printed
  as described above.

* bgpd/bgp_nexthop.c: zclient_new() already allocates stream for
  ibuf/obuf, so bgp_scan_init() shouldn't do it too.  Also, made it so
  zlookup is global so bgp_exit() can use it.

* bgpd/bgp_packet.c: bgp_capability_msg_parse() call to bgp_clear_route()
  adjusted to use new BGP_CLEAR_ROUTE_NORMAL flag.

* bgpd/bgp_route.h: Correct reference counter "lock" to be signed.
  bgp_clear_route() now accepts a bgp_clear_route_type of either
  BGP_CLEAR_ROUTE_NORMAL or BGP_CLEAR_ROUTE_MY_RSCLIENT.

* bgpd/bgp_route.c:
  - bgp_process_rsclient(): attr was being zero'ed and then
    bgp_attr_extra_free() was being called with it, even though it was
    never filled with valid data.

  - bgp_process_rsclient(): Make sure rsclient->group is not NULL before
    use.

  - bgp_processq_del(): Add call to bgp_table_unlock().

  - bgp_process(): Add call to bgp_table_lock().

  - bgp_update_rsclient(): memset clearing of new_attr not needed since
    declarationw with "= { 0 }" does it.  memset was already commented
    out.

  - bgp_update_rsclient(): Fix screwed up misleading indentation.

  - bgp_withdraw_rsclient(): Fix screwed up misleading indentation.

  - bgp_clear_route_node(): Support BGP_CLEAR_ROUTE_MY_RSCLIENT.

  - bgp_clear_node_queue_del(): Add call to bgp_table_unlock() and also
    free struct bgp_clear_node_queue used for work item.

  - bgp_clear_node_complete(): Do peer_unlock() after BGP_EVENT_ADD() in
    case peer is released by peer_unlock() call.

  - bgp_clear_route_table(): Support BGP_CLEAR_ROUTE_MY_RSCLIENT.  Use
    struct bgp_clear_node_queue to supply data to worker.  Add call to
    bgp_table_lock().

  - bgp_clear_route(): Add support for BGP_CLEAR_ROUTE_NORMAL or
    BGP_CLEAR_ROUTE_MY_RSCLIENT.

  - bgp_clear_route_all(): Use BGP_CLEAR_ROUTE_NORMAL.

  Bug 397 fixes:

    - bgp_default_originate()
    - bgp_announce_table()

* bgpd/bgp_table.h:
  - struct bgp_table: Added reference count.  Changed type of owner to be
    "struct peer *" rather than "void *".

  - struct bgp_node: Correct reference counter "lock" to be signed.

* bgpd/bgp_table.c:
  - Added bgp_table reference counting.

  - bgp_table_free(): Fixed cleanup code.  Call peer_unlock() on owner if
    set.

  - bgp_unlock_node(): Added assertion.

  - bgp_node_get(): Added call to bgp_lock_node() to code path that it was
    missing from.

* bgpd/bgp_vty.c:
  - peer_rsclient_set_vty(): Call peer_lock() as part of peer assignment
    to owner.  Handle failure gracefully.

  - peer_rsclient_unset_vty(): Add call to bgp_clear_route() with
    BGP_CLEAR_ROUTE_MY_RSCLIENT purpose.

* bgpd/bgp_zebra.c: Made it so zclient is global so bgp_exit() can use it.

* bgpd/bgpd.c:
  - peer_lock(): Allow to be called when status is "Deleted".

  - peer_deactivate(): Supply BGP_CLEAR_ROUTE_NORMAL purpose to
    bgp_clear_route() call.

  - peer_delete(): Common variable listnode pn.  Fix bug in which rsclient
    was only dealt with if not part of a peer group.  Call
    bgp_clear_route() for rsclient, if appropriate, and do so with
    BGP_CLEAR_ROUTE_MY_RSCLIENT purpose.

  - peer_group_get(): Use XSTRDUP() instead of strdup() for conf->host.

  - peer_group_bind(): Call bgp_clear_route() for rsclient, and do so with
    BGP_CLEAR_ROUTE_MY_RSCLIENT purpose.

  - bgp_create(): Use XSTRDUP() instead of strdup() for peer_self->host.

  - bgp_delete(): Delete peers before groups, rather than after.  And then
    rather than deleting rsclients, verify that there are none at this
    point.

  - bgp_unlock(): Add assertion.

  - bgp_free(): Call bgp_table_finish() rather than doing XFREE() itself.

* lib/command.c,h: Compiler warning fixes.  Add cmd_terminate().  Fixed
  massive leak in install_element() in which cmd_make_descvec() was being
  called more than once for the same cmd->strvec/string/doc.

* lib/log.c: Make closezlog() check fp before calling fclose().

* lib/memory.c: Catch when alloc count goes negative by using signed
  counts.  Correct #endif comment.  Add log_memstats_stderr().

* lib/memory.h: Add log_memstats_stderr().

* lib/thread.c: thread->funcname was being accessed in thread_call() after
  it had been freed.  Rearranged things so that thread_call() frees
  funcname.  Also made it so thread_master_free() cleans up cpu_record.

* lib/vty.c,h: Use global command_cr.  Add vty_terminate().

* lib/zclient.c,h: Re-enable zclient_free().