PPPoS was actually not thread safe, pppos_input() can be called from
lwIP user port at any time, whatever the PPP state is. It might even be
called during pppos_connect() and pppos_listen(), this is quite unlikely
the port do that but nothing prevent the user to since we document
pppos_input() as being thread safe.
Added a mutex if PPP_INPROC_MULTITHREADED is set and ensure pppos_input()
is safe in regard to other pppos_* functions.
Makes it clear we are initiating the PPP session with ppp_connect
(i.e. acting as a PPP client) so there is no confusion possible
between ppp_connect and ppp_listen.
Prepare for PPP_SERVER support, we need to move auth configuration before
lcp_allowoptions is copied into lcp_gotoptions. Restore unused
auth_reset() function using pppd original source code.
We don't need ask_for_local boolean, this is only useful for setup which
can determine the local IP address from the system hostname, which is
probably meaningless for embedded devices (and probably any devices).
It was actually only set by ip_check_options() which is commented out in
lwIP because we don't parse a config file nor check PPP configuration
(user is responsible about writing a configuration which is logical ;-).
Furthermore ask_for_local boolean never set actually had the wrong
default for PPP server setups.
PPP is now pointerful for a while, we don't need anymore accessor functions
for the unique PPP local and static control block. Replaced
ppp_set_netif_statuscallback() and ppp_set_netif_linkcallback() functions to
defines.
Removed pppapi_do_ppp_set_netif_statuscallback() and
pppapi_do_ppp_set_netif_linkcallback(), they were useless because
netif_set_status_callback() and netif_set_link_callback() can be
safely called while PPP status is in dead (= non open) state
and even before the PPP session is actually created at all.
pppos_create() can be called whether the modem is ready to process the
PPP session since pppos_create() does not start the PPP session anymore,
moved the advise from pppos_create() to ppp_open().
Added macro PPP_AUTH_SUPPORT, if none of auth protocols are enabled
(PAP, CHAP, EAP) we reduce PPP memory usage by compiling out all
struct fields and source code used for authentication.
We only need to keep track of existing PPPoS interfaces if PPPoS
is not the only enabled protocol.
PPP CORE does not have callbacks pointers for all PPPoS callbacks
which should actually be required for PPPoS (VJ config, asyncmap, ...),
there is too much callbacks to create and PPPoS must be kept light,
especially for users who are only using PPPoS.
But there is a drawback, PPP CORE does not know which
lower protocols it is talking to thanks to the abstraction,
therefore if PPPoS is enabled as well as PPPoE or PPPoL2TP there
might be situation where PPP CORE calls pppos_ config functions
on interfaces which are NOT PPPoS one. This is very unlikely to
happen because protocols not supported by PPPoE or PPPoL2TP are
disabled at LCP/IPCP negotiation but we are better safe than sorry.
So we check if passed PPP pointer to PPPoS configuration functions
is a PPPoS interface by checking against a linked list of existing
PPPoS interfaces.
