add 'extern "C" {}' for cplusplus in ppp headers

PPP, IPCP: fix reset state before reconnecting

Commit 7df5496e7b revealed a regression introduced in commit 5a71509353
which broke IPCP reset state.

ask_for_local was set to 0 if ouraddr initial value is 0, if
ask_for_local was false go->ouraddr was cleared in reset callback,
commit 5a71509353 breaks it by removing this clearing. This regression
was silent because the whole ppp pcb runtime data was cleared before
reconnecting until commit 7df5496e7b which removed this giant clearing.

Fix it by reintroducing ask_for_local boolean value, with proper initial
value following what unused function ip_check_options do.

Fixes: 7df5496e7b ("PPP, rework initial/reconnect cleanup")
Fixes: 5a71509353 ("PPP, CORE, IPCP: removed useless ask_for_local boolean")

PPP: revamp PPP state order

Master state is almost exactly the same thing as dead state, move it
next to dead state. Holdoff state is actually the state just before
initialize, move it before initialize.

The goal is to be able to use > running or => terminate condition to
check a currently running disconnection phase, which is not possible
today without excluding master and holdoff states.

Fix bug #48436: Naming clash for timers.c (with FreeRTOS)
Rename timers.* to timeouts.*

PPP: introduce ppp_set_neg_pcomp, ppp_set_neg_accomp, ppp_set_neg_asyncmap, ppp_set_asyncmap

We are now able to add as many macros as necessary to change the PPP
configuration. Those are various usually used PPP options.

PPP: improve various comments on options

PPP: introduce ppp_set_passive and ppp_set_silent

There is two passive modes for PPPoS, passive more, for which we will
try to connect and then listen silently, and silent mode, for which we
will listen silently from the beginning.

Introduce ppp_set_passive and ppp_set_silent so the mode can be chosen
before connecting/listening.

PPP: don't build ppp_set_auth if no authenticator are enabled

For our few users which might disable all authenticators to save some
flash, ensure that everything using authentication is build out.

PPP, PPPAPI: remove useless pppapi_set_auth function

Setting PPP authentication most only be done when the PPP PCB is in the
dead phase (i.e. disconnected). This is safe to access the PPP PCB
members while the session is down, therefore providing a thread-safe
function of it is meaningless and it might even be misleading.

All our new ppp_set_* functions do not have their equivalent
pppapi_set_* functions and they are not going to have them. At least
we make ppp_set_auth consistent with all others ppp_set_*, so that it
doesn't look like special.

PPP: introduce ppp_set_mppe

Helper function to setup MPPE (Microsoft Point to Point Encryption) for
a PPP link. Allows enabling/disabled MPPE itself, enabling/disabling
stateless support, and whether we are willing to negotiate 40-bit
and/or 128-bit encryptions.

PPP: introduce ppp_set_listen_time

Wait for up to the specified milliseconds for a valid PPP packet from
the peer. At the end of this time, or when a valid PPP packet is
received from the peer, we commence negotiation by sending our first
LCP packet.

This is useful because PPP does not deal properly when both peers
are sending the first LCP packet in the exact same time, which causes
delays because they both wait for a reply for their own packet.

PPP: introduce ppp_set_auth_required macro

PPP auth required flag is currently hardcoded to true if PPP is
acting as a server and set to false if PPP is acting as a client.

This is probably the most wanted behavior, but since we now have the
ability to change that at runtime, allow users to do it.

It means we can now have a server which asks the client to authenticate
or vice versa. This is pretty unusual thought. What we don't support
yet is mutual authentication with a different set of user and password
per direction which is even less usual.

PPP, DNS: introduce ppp_set_usepeerdns macro

PPP use peer DNS setting is currently hardcoded to true if PPP is
acting as a client and set to false if PPP is actinf as a server.

This is probably the most wanted behavior, but since we now have the
ability to change that at runtime, allow users to do it.

We don't have a way to have a different default configuration if the
PPP PCB is going to be used as a client or as a server, therefore the
default configuration should be fine for both of them. Since enabling
peer DNS by default is dangerous for server mode, the default is now
not to ask for DNS servers and it should now be explicitely enabled
if needed, update the documentation accordingly.

PPP, PPPoS, SERVER: remove useless struct ppp_addrs* argument from pppos_listen

Now that we have helpers to set those members externaly, pppos_listen
struct ppp_addrs* argument does not add any value. In addition it
was not a well chosen design choice because the user needed to keep a
copy of struct ppp_addrs when listening again for a new connection.

PPP, add configuration macros to set IPCP our, his, and DNS IPv4 addresses

Mostly for PPP server support, but not limited too, we need a way to
configure static IPv4 addresses for our side (our), peer side (his),
and two DNS server addresses if peer asks for them.

PPP, fix comment about opt.h (moved to ppp_opts.h)

PPP defines were moved from opt.h to ppp_opts.h but comments
referencing opt.h in PPP were not updated.

PPP, rework initial/reconnect cleanup

Our previous way of doing it was to clear everything except a small part
of the ppp_pcb structure and then populate the structure with default
values using protocols init functions.

But it means the user is currently not allowed to change the default
configuration except the few flags and values that are currently
available in the ppp_settings structure.

Instead of adding more and more fields to the ppp_settings structure,
actually making them duplicate of already existing structure members
of ppp_pcb, but unfortunately cleaned, we carefully checked that
everything is properly cleaned during protocol lowerdown/close and
replaced our giant memset to selective memset of the few ppp_pcb
members that are not properly cleaned.

PPP: remove sio.h from included files

PPP is not using the SIO API anymore for quite a while. Remove now
useless sio.h from included files.

Fix bug #47507: PPP API does not support LWIP_MPU_COMPATIBLE
I'd be glad if someone would test it :-)
Sylvain, if you don't like this patch feel free to revert it

Work on task #13907 PPP cleanups: Move PPP options from opt.h to dedicated ppp_opts.h file

PPP: CCP: don't drop output packets if CCP negotiated that we don't compress on our side

CCP might negotiate to not compress if peers cannot agree on a
compressor, therefore if the null compressor is chosen we must pass
packets as is instead of dropping them.

Reported-by: Stephan Linz <linz@li-pro.net>
Fixes: 987f6237c4 "PPP, MPPE, drop input/output packets if we couldn't find the chosen decompressor/compressor"
Signed-off-by: Sylvain Rochet <gradator@gradator.net>

PPP, don't store the name by which the peer authenticated itself to us if multilink support is disabled

pcb->peer_authname is only used by multilink support (which we don't
support), don't store the useless peer authname.

PPP, removed useless padding in bitfields

Most of them were wrong actually. We have to use unsigned int because
C90 only allows int types for bitfields, so we are stuck to 32-bit
bitfields in most cases.

PPP, VJ, CCP: rework to fix protocol order

We need to do VJ compression before CCP/MPPE compression and VJ
decompression after CCP/MPPE decompression. This leads to a massive
rewrite of how we currently handled VJ only in the PPPoS lower protocol
handler.

Moved VJ structures from pppos to ppp_pcb because we need them back in
PPP core. This is a bit unfortunate because that's not necessary for
PPPoE or PPPoL2TP, but, hey!. Fixed CCP+MPPE+VJ order.

PPP, CCP, added data packet configuration in ppp_pcb

PPP, CCP, added MPPE user configuration flags

PPP, MSCHAP, CCP, MPPE: reworked key passing from CCP to MPPE

Removed mutiple copies of keys by pre-setting MPPE keys during MSCHAP
negotiation.

Improved MPPE init so we don't need to pass a buffer formatted in a
special way to MPPE, this is necessary for pppd to talk to the kernel,
we don't need that here.

PPP, CCP, reworked ppp_pcb ccp_localstate and all_rejected fields

PPP, MPPE, moved MPPE global variables from MSCHAP to ppp_pcb

PPP, MPPE, added ppp_mppe_state comp and decomp to ppp.h

PPP, CCP, deflate, BSD compress, predictor 1 & 2 are now optional at compile time

task #12722 (improve IPv4/v6 address handling): renamed ip_addr_t to ip4_addr_t, renamed ipX_addr_t to ip_addr_t and added IP version;
ip_addr_t is used for all generic IP addresses for the API, ip(4/6)_addr_t are only used internally or when initializing netifs or when calling version-related functions

PPP, MPPE, updated polarssl ARC4 for lwIP

PPP, MPPE, replaced #ifdef MPPE to #if MPPE_SUPPORT

PPP, CORE, removed auth fields from struct ppp_pcb if auth is disabled

PPP, CCP, various fix if MPPE is enabled

PPP, CCP, added ccp.h in ppp.h

PPP, CCP, moved CCP global variables to ppp_pcb (ppp.h)

PPP, ppp->last_xmit is only used in PPPoS, moved to PPPoS

Only PPPoS need to keep track of last transmitted packet for HDLC flag,
removed from PPPoE and PPPoL2TP and moved to PPPoS.

PPP, PPPoS, moved pcomp and accomp only used by PPPoS to PPPoS

PPP, PPPoS, moved vj_enabled flag from PPP CORE to PPPoS

Now that we have flags in PPPoS, moved vj_enabled only used for PPPoS to
PPPoS.

PPP, IPCP, removed proxy ARP support

PPP, removed now useless struct ppp_addrs from ppp_pcb

Saved a few bytes of useless copy.

PPP, make DNS a little more optional if LWIP_DNS is unset

PPP, renamed ppp_open to ppp_connect

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.

PPP, SERVER: added PPPoS server support

New function: ppp_listen(), listen for an incoming PPP connection.

PPP, SERVER: statically define our name for authentication purposes

We don't need that in RAM nor a pointer to a string, a static
define is fine for embedded devices, saved ~257 bytes of RAM.

PPP, CORE, beautified ppp_set_auth()

Beautified, added PPPAUTHTYPE_MSCHAP_V2 choice support.

PPP, CORE, cleaned struct ppp_settings coding style

PPP, CORE, IPCP: removed useless ask_for_local boolean

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, CORE, cleaned ppp_close() function

Calling new_phase() instead of assigning pcb->phase directly.
Removed redundant call to link status callback.

PPP, CORE, functions ppp_set_netif_statuscallback() and ppp_set_netif_linkcallback() replaced with defines

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.

PPP, PPPoS, moved advise about modem from pppos_create() to ppp_open()

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().

PPP, CORE, ppp_close() and ppp_sighup() ended up sharing almost everything, merged

Merged ppp_sighup() to ppp_close() using an optional argument "nocarrier"
on ppp_close().

PPP, CORE, disable VJ is PPP IPV4 is compiled out

VJ compression is only supported for PPP IPv4, compile out VJ support
if PPP IPv4 is not compiled.

PPP, IPv4 support is now optional

New compile time option: PPP_IPV4_SUPPORT

PPP IPv4 support can now be compiled out.

PPP, CORE, improved, re-ordered and re-numbered IOCTL commands

PPP, CORE, using u8_t on ioctl command instead of int

We don't need an int here, all commands are between 0 and 255.

PPP, CORE, compile out auth support if none of auth protocols are enabled

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.

PPP, using PPP netif->num number instead of ppp->num

Saved 2 bytes of RAM if debug is enabled, we are now using the
netif->num number instead of using our own ppp->num

PPP, using err_t return code instead of PPPERR_

Standardised PPP API to follow lwIP already used return codes.
PPPERR_ are now used only on link status callback.

PPP, using err_t return type on ppp_ioctl()

PPP, CORE, now using const callbacks struct from lower level protocols

Saving some RAM by using callbacks struct in rodata for required
callbacks called by PPP core to PPP low level protocols.

PPP, CORE, prepared for lower protocols callbacks returning state

Until now, callbacks used void return, preparing callbacks to return
PPPERR_ status.

PPP, PPPoS, moved out_accm from PPP core to PPPoS

Last PPPoS variable in PPP core moved to PPPoS.

PPP, PPPoS, removed xmit_accm, almost duplicate of out_accm

xmit_accm was meant to be a user configurable asyncmap, it was actually
broken since the introduction of ppp_new by the way we now reset the PPP
initial state, looks like no one until now is needing it anymore. If
necessary we will reintroduce this feature later properly instead of a
dirty and ugly hack into the PPP code.

PPP, PPPoS, moved ppp.rx to pppos.rx

PPP rx control block moved to PPPoS

PPP, PPPoS, moved VJ from PPP core to PPPoS

VJ is only available for PPPoS, moved VJ from PPP CORE to PPPoS.

PPP, PPPoS moved fd from ppp_pcb to pppos_pcb

Moved fd from ppp_pcb to pppos_pcb.

However PPP ioctl PPPCTLG_FD is temporarily disabled until I found a
better solution.

PPP: Moved PPPoS from ppp.c to pppos.c

Started removing from PPP core most of low level protocol PPPoS
handling to separate files, using the new low level PPP callbacks.

PPP, generalized callbacks calls from PPP core, removed all PPPoE and PPPoL2TP references

Almost there, removed all PPPoE and PPPoL2TP references from PPP core,
using the generic callbacks interface everywhere.

PPP, removed low level create functions from PPP core

ppp_over_ethernet_create() moved from ppp.c to pppoe.c
ppp_over_l2tp_create() moved from ppp.c to pppol2tp.c

PPP, moved ppp_write and ppp_netif_output low level protocols functions to respective low level protocol files

Moved ppp_write_over_ethernet() and ppp_netif_output_over_ethernet() to pppoe.c
Moved ppp_write_over_l2tp() and ppp_netif_output_over_l2tp() to pppol2tp.c

PPP, prepare new callbacks for low level protocols

New callbacks: write and netif_output

PPP: prepared callbacks from PPP core to low level protocols

New PPP callback from PPP core to low level protocols, first
step about removing named calls to low level protocols from PPP core.

PPP: re-order functions in the common sense API order

Re-order ppp.[ch] functions in the order functions should be called from
user application. Moved create functions, which actually return a PPP
control block before functions needing a PPP control block.

PPP: moved ppp_new() to low level protocol init for PPPoE and PPPoL2TP

First step of a rework of how low level protocols are using the
PPP core. Low level protocols are now going to use the core instead
of core using the low level protocols.

Final goal: separate PPP core code from low level protocols.

PPP: re-order functions in the common sense API order

Re-order ppp.[ch] functions in the order functions should be called from
user application. Moved create functions, which actually return a PPP
control block before functions needing a PPP control block.

PPP: using a macro for ppp_set_default() instead of a function

This function is only calling netif_set_default(), a macro
is adequate.

PPP: removed ppp_delete(), merged with ppp_free()

The only benefit of ppp_delete() call was about having a persistent
netif interface. netif was moved out of PPP pcb so we don't need
ppp_delete() anymore, second step in simplifying the weird
new/open/free/delete PPP API.

PPP: removed ppp_new(), merged with ppp_over_X_create()

The only benefit of ppp_new() call was about having a persistent netif
interface. netif was moved out of PPP pcb so we don't need ppp_new()
anymore, first step in simplifying the weird new/open/free/delete PPP
API.

PPP: moved netif out of PPP control block

Users might want to share a netif control block between an Ethernet
interface and a PPPoS interface (I want actually) in case PPP is just
used as redundancy if Ethernet is down (eg. PPPoS GPRS fail over).

Moved netif out of PPP control block in a similar way it is currently
done for Ethernet interfaces. Furthermore, this is a first step on
removing the "new/create/free/delete" API which is awful but currently
necessary to handle fail over from PPPoX to another PPPoX (eg. from PPoE
on xDSL to PPPoS on GPRS fail over) without free()ing the netif which
might be used on udp_sendto() or L2TP VPN links.

PPP, from PPPD upstream, separate IPv6 handling for sifup/sifdown

The current code is buggy regarding handling of link state when using
both IPCP and IPv6CP: if IPv6CP has been set up and if during IPCP
negociation, ipcp_up() fails, it will incorrectly take the interface
down. The simple solution here is to change the platform code to do the
same as on Solaris: separate IPv6CP up/down state handling with sif6up()
and sif6down(), so that we really know when the interface is allowed to
go down.

(Based from pppd commit b04d2dc6df5c6b5650fea44250d58757ee3dac4a)

PPP,SLIP include lwip/sio.h after lwip/sys.h to prevent functions prototype collision

User port may redefine sio_* functions, we must ensure we are loading
user functions prototypes before loading default prototypes.

PPP, moved ppp_init() from public API (ppp.h) to private API (ppp_impl.h)

ppp_init() is called by lwip_init(), users don't need to init PPP by themselves

PPP, added const modifier on auth strings

PPP, fixed some compiler warnings

Using -Wall -pedantic -Wparentheses -Wsequence-point
-Wswitch-default -Wextra -Wundef -Wshadow -Wpointer-arith
-Wbad-function-cast -Wc++-compat -Wwrite-strings -Wold-style-definition
-Wmissing-prototypes -Wredundant-decls -Wnested-externs -Wno-address

fixed bug #43235, checking for non-existent preprocessor macros is non-standard, added predefinition for all affected macros

PPP, most PPP headers are using u_long, u_int, u_short and u_char types, moved typedef of those types before we include any PPP header

PPP, added PPP notify phase support

PPP notify phase support, using compile-time PPP_NOTIFY_PHASE macro.

This can be used for example to set a LED pattern depending on the
current phase of the PPP session.

Callback example:

static void ppp_notify_phase_cb(ppp_pcb *pcb, u8_t phase, void *ctx) {
switch(phase) {
case PPP_PHASE_DEAD: /* Kept off */
case PPP_PHASE_MASTER:
/* LED Off */
break;
case PPP_PHASE_INITIALIZE: /* Session opened */
/* LED FastBlink */
break;
case PPP_PHASE_RUNNING: /* Session running */
/* LED On */
break;
default:
/* LED SlowBlink */
}
}

PPP, moved PPP_INPROC_MULTITHREADED compile time option from ppp.h to opt.h

PPP, removed PPP_INPROC_OWNTHREAD feature, which almost only make things harder

I consider to remove the PPP_INPROC_OWNTHREAD crap in ppp-new,
as said in bugs #37278 and #37353.

1. It requires the ppp_input_thread() function to be modified to match
user system, like some did by adding the vTaskDelete(NULL); FreeRTOS
call at the end of the function, for example.

This is a tiny-tiny fonction that should be, in my opinion, on the user
port, like the Ethernet input thread we see in many Ethernet port.

2. It is actually not that thread safe.

2.1. pcb->phase IS modified by the lwIP core thread so it should at
least be set to volatile, otherwise the pcb->phase copy may live
indefinitely in CPU register. It works because of the sio_read()
function call which without doubt flush pcb->phase copy from CPU
register. I dont want to set ppp_pcb struct to volatile for obvious
performance reasons.

2.2. This function assume PCB still exists whatever is happening, which
is not the case after you called ppp_delete() function outside of this
thread. If sio_read() is blocking waiting data and pcb destroyed, it is
going to read a deallocated pcb which luckily should still have
pcb->phase set to 0 (=PHASE_DEAD) due to preallocated "control block"
structures of lwIP. Even with sio_read_abort(), there might be timings
issue due to a lack of a synchronization mechanism.

3. I dislike the sys_msleep(1), it means that systems should have at
least a 11 chr buffer at 115200/10 byte/s, and bigger with higher serial
speed, for example with 3G/HSDPA modems accessed through SPI, at 20
Mbits/s this is a ~2000 bytes buffer required to keep incoming data
during this sleep, I don't see why we require systems to do so,
sio_read() should obviously be a blocking call. I cannot easily
remove this sleep because some systems might have wrongfully used this
call as a CPU idle feature with a non blocking sio_read() call.

PPP, added ppp_free()

Free the control block, clean everything except the PPP PCB itself
and the netif, it allows you to change the underlying PPP protocol
(eg. from PPPoE to PPPoS to switch from DSL to GPRS) without losing
your PPP and netif handlers.

PPP, slight API change, great code factorisation

Created new ppp_over_X_create() functions which only prepare the PPP session without starting it
Removed ppp_reopen() and all of its sub ppp_over_X_reopen()
Removed PPPoL2TP reconnect() function, merged to connect()
Added ppp_open() able to start or restart any session

PPP, added ppp_addrs() macro to get the pointer of the ppp->addrs struct

PPP, moved FSM configuration to ppp_settings struct

PPP, moved EAP configuration to ppp_settings struct

PPP, moved PAP configuration to ppp_settings struct

PPP, improved PAP and CHAP timeout/request/maxrequests configuration values

PPP, changed all the code enclosed between PPP_SERVER #if macro to our PPP PCB structure, making it easier to support PPP server in the future

PPP, cleaned MTU,MRU variables

PPP, removed unnecessary ethif from ppp_pcb

PPP, cleaned persist and holdoff features

Moved PPP headers into include/netif/ppp/, fixing bug #37040.