If a HELLO message can't be acknowledged just log an error as tunnel
doesn't need to get closed. If too many HELLO messages aren't
acknowledged, the peer will close the tunnel itself.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

If tunnel or session establishment timeout expires, send StopCCN or CDN
to notify peer before closing tunnel/session.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Always disconnect tunnel once l2tp_tunnel_disconnect() is called,
even if sending StopCCN failed.
Change the way unknown message types are handled to comply with
new l2tp_tunnel_disconnect() signature.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Don't terminate tunnel in case of error while handling a duplicate
message. Such errors aren't critical enough to justify termination
of a tunnel and all of its sessions.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

When starting a tunnel created upon user request, free it in case
of error.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

A side effect of setting peer port to zero when sending SCCRQ messages
is that the tunnel can't send any new message before receiving first
peer's answer (this doesn't apply to retransmissions as peer port is
set in the original packet). It is then impossible to send StopCCN
messages within this time frame.

This patch fixes this issue using a new tunnel flag which indicates if
tunnel's peer port has a default value or if it has been set after
reception of peer's first message.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Handle tunnel timeout timers in l2tp_tunnel_start() and
l2tp_tunnel_connect(). This avoids timer code duplication across
functions that are spectific to the tunnel establishment mode.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Start and stop session timeout timers in l2tp_tunnel_start_session()
and l2tp_session_connect(). This unifies timers management across the
four different ways of creating sessions.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Define l2tp_session_incall_reply() which can be used as
parameter for l2tp_tunnel_start_session(). This removes
the need for updating session's state in l2tp_send_ICRP()
and normalises the way incomming and outgoing sessions are
handled.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Define l2tp_session_place_call() which can start either an incomming
or outgoing session depending on the 'sess->lns_mode' flag. This
removes the need for testing session mode before calling
l2tp_tunnel_start_session().
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Creating new sessions always involves the same steps:
  * Create new session context
  * Call session's first function in this context
  * Start session establishment timer

This patch starts centralising the first two steps in
l2tp_tunnel_confirm_session() (renamed l2tp_tunnel_start_session()
in order to use similar ways for starting tunnels and sessions).
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Handling ICRQ or OCRQ requests occurs in tunnel context, but if session
creation is rejected, a CDN has to be sent. However, l2tp_send_CDN() is
supposed to be called in session context. This means that it uselessly
switches to tunnel context before sending messages and requires a
session structure to work on.

This patch creates a new function for sending CDN from tunnel context.
It gets the session and peer session IDs from its arguments and calls
l2tp_tunnel_send() directly. The l2tp_recv_ICRQ() and l2tp_recv_OCRQ()
functions are modified to take advantage of this new function and will
now send CDN even upon early message processing error.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Define the l2tp_{tunnel,session}_send() functions for sending
messages in tunnel or session context. Session messages have
their session ID automatically set and switch to tunnel context
for sending messages.

Though the 'debug' parameter is removed from function prototypes,
the logging mechanism is respected: HELLO and ZLB are displayed as
'debug' messages while other message types use 'info2'.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Print details about errors that can occur when using the
"l2tp create tunnel" command line.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Print details about errors that can occur when using the
"l2tp create session" command line.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Check for errors in start_udp_server() and return exit status to
calling function.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Use memdebug variants of {m,re}alloc() so that the corresponding
_free() will work correctly if MEMDEBUG is defined.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Update l2tp_session_free's prototype to return its error status.
Do the opposite for l2tp_tunnel_cancel_session (make it return void)
as it never fails.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Define macros for logging tunnel or session messages with automatic
context information display.
Use these macros to replace most existing error messages + add
missing ones.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Add entries in accel-ppp.conf.5 for configuration options defined by
the CLI module.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Define the "sessions-columns" option (in the [cli] section) to let
the user select the default set of columns that will be displayed by
the "show sessions" command.
Unrecognised column names are silently discarded.

Configuration example:
    [cli]
        telnet=127.0.0.1:2000
        password=secret
        sessions-columns=ifname,ip,username
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Gracefully handle the case where no column has been selected for the
"show sessions" command. Such situation will be possible once the set
of default displayed columns will be made configurable from
accel-ppp.conf.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

When several messages are sent consecutively, the peer can reply with
a single ZLB to acknowledge all messages. In this case, removing
only the first message from the retransmission queue isn't enough
(acknowledged messages left in the queue will be retransmitted).
This case can happen when replying to an outgoing call request, wich
is handled by sending two messages in a row (an OCRP and an OCCN).

This patch avoids useless retransmissions by removing all messages
acknowledged by peer from the retransmission queue.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Handle OCRQ requests when operating as LAC.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Send the Result and Error fields of StopCCN and CDN messages in network
byte order.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Use the Assigned Tunnel ID and Result Code AVPs when handling StopCCN
messages.
The Result Code AVP is used to improve log messages, while the Assigned
Tunnel ID is used to set the tunnel's peer-tid field.

Setting peer-tid makes the ZLB to be sent to the right tunnel in case
no Assigned Tunnel ID had been received yet (this happens when the host
sends an SCCRQ but the peer directly rejects the connection with
StopCCN).
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Send a ZLB after reception of Set-Link-Info (SLI) messages to avoid
retransmissions from the LNS.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Fix a few errors in dictionary.rfc2661 and dictionary.rfc3931 (missing
entries, typos, wrong type/flags, etc.) and re-generate attr_defs.h.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Add const qualifier to attributes pointers used for parsing incoming
L2TP messages.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Add const qualifier to the Message Type variable used by the generic
L2TP reception functions.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Add const qualifier to packet passed to l2tp_recv_*() functions.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Define the address parameter of l2tp_packet_alloc() as constant.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Add const qualifiers to the string used for reading configuration.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Declare parameters and variables of l2tp_packet_print() as constant.
Also update l2tp_dict_find_value() prototype to accept options passed
by l2tp_packet_print().
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Handle CLI_CMD_FAILED like other command errors (i.e. return 0 to the
caller and send a generic error message).
This makes the CLI handler to flush its input buffer, so that
processing of the next command will be made correctly. This also makes
the telnet handler to send its prompt message.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Refuse to initiate tunnel creation to peers not defined in the
"client-ip-range" configuration section.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Don't call strlen() if conf_secret is NULL.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

Implement incomming call placement for tunnels operating as LAC.
A user can place incomming calls using the command line interface.
For example, the following command will place a call on tunnel 1:
  accel-ppp# l2tp create session tid 1
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>