Signed-off-by: NDmitry Kozlov <xeb@mail.ru>

Signed-off-by: NDmitry Kozlov <xeb@mail.ru>

Signed-off-by: NDmitry Kozlov <xeb@mail.ru>

Signed-off-by: NDmitry Kozlov <xeb@mail.ru>

Use unshare(CLONE_FILES) to create a local file descriptors namespace
for the SNMP thread. This is similar to what was done in bf5340
'net-snmp: run snmp in "special" thread', but without calling clone()
directly. So the net-snmp plugin keeps running in a regular pthread.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

This reverts commit bf534029.

snmp_thread() needs to be run as regular thread to allow Valgrind
analysis. Using a different namespace for file desciptors will be
done later on using unshare().
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

If accel-ppp is compiled with RADIUS support, but run without using it,
then pd->tmp_fname is NULL. This patch verifies that pd->tmp_fname is
valid before renaming the radattr file.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

ipoe: early allocate interface for shared vlans (prevents different values of NAS-Port in Access-Request and Account-Request)
Signed-off-by: NDmitry Kozlov <xeb@mail.ru>

Signed-off-by: NDmitry Kozlov <xeb@mail.ru>

NET-SNMP is built on top of stale file descriptor multiplexing mechanism (select)
which prevents to use descriptors with number >= 1024.
Due to accel-ppp uses a lots of descriptors NET-SNMP easy overflows this limit and fails
and even may crash whole accel-ppp process.
This patch runs snmp in special thread which does not share file descritor table
with main process, so it can use less descriptors and live in __FD_SETSIZE limit.
Signed-off-by: NDmitry Kozlov <xeb@mail.ru>

Wait for a full retransmission cycle after reception of a StopCCN.
Introduce STATE_FIN_WAIT to identify tunnels which have received a
StopCCN but are waiting for the disconnection timer to expire.

A tunnel can go from STATE_FIN (i.e. StopCCN has been sent, waiting for
acknowledgement) to STATE_FIN_WAIT (i.e. StopCCN has been received,
waiting for full retransmission cycle), but not the other way around.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

  * Set default retransmission timeout to 1 second. Since we now have
    exponential backoff, we can afford a smaller value.

  * Add the rtimeout-cap option to set the maximum value the
    retransmission timer has to respect during exponential backoff.

  * Store the maximun number of retransmissions in tunnel's structure
    (like other retransmission parameters).

  * Describe all these changes in man page and reset them to their
    default values if they're removed from configuration file before a
    reload.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Rework the l2tp_rtimeout() callback, so that time between
retransmissions expands exponentially. This allows for faster
retransmissions without without overwhelming the peer.

A cap is set on the maximum retransmission time. For now it is set to
16 seconds.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

If a peer needs to disconnect a session for which it didn't receive
any reply, it sends a CDN with no Session ID. In this case, the
Assigned Session ID AVP is the only data that can be used to find out
which session has to be closed. Though it isn't supported for now,
let's accept and ack these messages. Session will be deleted on our
side thanks to the establishment timer.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Add the recv-window option in accel-ppp.conf.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Add a fixed length receive queue to tunnels and adverdise its length to
the peer using the Receive Window Size AVP.

Incoming message handling is modified as follow:
  -Read as much messages as possible and store them in the receive queue.
   Messages are stored in order, based on their sequence number. Messages
   not fitting into the queue are discarded (doesn't happen if peer
   respects our Receive Window AVP). This is the job of the new
   l2tp_tunnel_store_msg() function. It also automatically finds out if
   there are new messages to acknowledge.

  -Once all incoming messages have been read, free acknowledged packets
   from retransmission queue (based on the highest received
   acknowledgement number).

  -Then process messages in the receive queue. This is done by
   l2tp_tunnel_reply().  Each packet is processed by
   l2tp_{tunnel,session}_recv() (or dropped in some particular cases).
   The send queue is then pushed. If there's no message in the send
   queue and an acknowledgement is necessary, a ZLB is sent instead.

  -Finally, detect if the peer has acknowledged a StopCCN. There are
   three components to this test:
     -Have we tried to send a StopCCN? Check with tunnel's state.
     -Has the StopCCN been pushed on the network? Check with tunnel's
      send queue.
     -Has the peer acknowledged the StopCCN? Check with tunnel's
      retransmission queue.

For now, l2tp_tunnel_store_msg() doesn't perform fast retransmissions.
So l2tp_retransmit() is removed.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Use stacked error labels for better extensibility.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Refuse to create new sessions when the local send queue is bigger than
the peer's receive window (i.e. when there are already more outstanding
messages than what the peer can currently accept). Only sessions
initiated locally are affected, session requests from the peer are
still handled normally.

This avoids adding useless presure on the sending window when many
sessions are created locally. If sessions were created, they'd add
many ICRQ or OCRQ messages in the send queue and we'd have to wait for
all these messages to be sent before being able to reply to messages
from the peer.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Store the Receive Window Size AVP sent by peer and respect it when
sending messages. That is, stop sending messages from send queue once
the number of unacknowledged messages is higher than peer's receive
window.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Add a per session send queue. Messages sent by a session are added to
both tunnel and session queues. This allows sessions to remove their
unsent messages from tunnel's send queue before they disconnect.

The same approach is used for tunnels. Before disconnecting, they clear
their send queue to avoid sending useless messages.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Modify return value of l2tp_tunnel_push_sendqueue() to inform the
caller if a message has been sent or if the queue was empty. This
information, let l2tp_conn_read() automatically acknowledge
received messages using a ZLB when there's no response to send.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Stop checking for l2tp_{tunnel,session}_send() return values.
These functions now always succeed, unless the session or tunnel is
closing (in which case packet is automatically dropped and caller
doesn't need to take any special action).
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Don't send messages immediately, store them in conn->send_queue
instead, so we have control over how many and when messages are
sent on the network. Once a message is sent, it's removed from
the send queue and added to the retransmission queue.

Retransmission queue is automatically updated based on acknowledgements
received from peer.

For now, packets in the send queue are pushed on the network after
each incoming packet processing. So functions called by l2tp_conn_read()
don't have to call l2tp_tunnel_push_sendqueue().
Other functions (e.g. triton callbacks) have to manually push packets
out of the send queue.
The same applies for disconnection. The l2tp_tunnel_disconnect_push()
and l2tp_session_disconnect_push() functions have been defined for use
in functions that don't call l2tp_tunnel_push_sendqueue() automatically.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Remove message type switch from l2tp_conn_read(). Define
l2tp_tunnel_recv() instead to handle tunnel specific messages.
The Session ID field in L2TP control messages is used to determine if
packet is tunnel or session oriented.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Let l2tp_tunnel_disconnect() delete the tunnel when an error occurs.
Return an int to indicate if conn has been deleted.

Most callers are compatible with this new behaviour, either because
they never use the tunnel after disconnection or because they hold
a reference on the tunnel.

A few callers need to be adapted though:
  -l2tp_conn_close() calls l2tp_tunnel_disconnect() to properly inform
   the peer of tunnel disconnection. But it also deletes the tunnel
   immediately, no matter if StopCCN message was sent or not. Since
   l2tp_conn_close() doesn't hold a reference on the tunnel, care must
   be taken not to access the tunnel if it was deleted by
   l2tp_tunnel_disconnect().
   Since immediate deletion isn't required, the l2tp_tunnel_free() call
   is simply removed. The normal disconnection process is now followed,
   with detection and retransmission of lost messages, acknowledgment
   handling, etc.

  -situation is similar for l2tp_tunnel_timeout() and handled in the
   same way.

This patch also deletes tunnel's sessions, as well as the establishment
and hello timers. These are of no use once the tunnel enters the
disconnection process.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Now that l2tp_tunnel_free() can be called directly inside the main
reception loop, let l2tp_recv_StopCCN() delete the tunnel itself.
This avoids special handling in l2tp_conn_read().
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Let functions launched by l2tp_conn_read() delete the tunnel. This is
done by taking a reference on conn to ensure it'll remain a valid
tunnel, even after calling l2tp_tunnel_free(conn).

l2tp_conn_read() now detects if conn got deleted, so that we know if
the tunnel still holds a reference to itself. If it doesn't,
tunnel_put() may free the tunnel and thus the triton handler we're
running from. So we have to return -1 in this case.

l2tp_tunnel_free() also needs to be modified: it can't safely close
conn->hnd.fd anymore. Since l2tp_conn_read() relies on conn->hnd.fd
being a valid file descriptor, closing it inside the reception loop
would break this assumption in next iteration.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Upon failure, l2tp_recv_SCCRP() and l2tp_recv_SCCCN() disconnect their
tunnel, which is then immediately deleted by l2tp_conn_read(). Deleting
the tunnel isn't necessary at this stage and prevents retransmission of
the disconnection message if it gets lost. Same applies to unknown
message types with M bit set.

This path avoids immediate tunnel deletion, thus allowing the
disconnection process to handle acknowledgments from peer and to
retransmit messages if necessary.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

  * Add list_first_entry() to list.h
  * Declare parameter of list_empty() as const

Both changes are already included in Linux kernel sources.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Re-use the Session ID selection algorithm for generating Tunnel IDs.
When a peer always uses the same source port for establishing tunnels,
and if ephemeral ports aren't activated (default), then Tunnel IDs are
the only way to identify tunnels. Using ramdom Tunnel IDs then
minimises the risk of re-using IDs of half-closed tunnels (i.e. tunnels
closed locally, but still existing on the peer side).

As a minor side effect, the maximum value of a Tunnel ID is now
2^16 - 1.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Don't give up immediately when generating a new Session ID fails. Keep
trying until a valid Session ID is found. Abort when the number of
attempts exceeds the number of valid Session IDs.

This is derived from algorithm 3 of RFC 6056 (Port Randomization
Recommendations). Other algorithms may be used later on if need be.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

  * Add "secret" to the list of options accepted by the
    "l2tp create tunnel" command.
  * Display one option per line to avoid too long help message.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Replace cli_sendv by cli_send where possible.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Verify tunnel or session states before handling HELLO, StopCCN and CDN
messages.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

WEN and SLI messages carry session specific data and should be handled
by the session rather than by the tunnel. Session's state can now be
checked before accepting these message types.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

l2tp_conn_read() already has code to free received packets. Let
l2tp_session_recv() take advantage of it.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>