PPP, IPCP: check that the peer is allowed to use the IP address it wants

This is done in the pppd upstream and was disabled because we don't have
the allowed addresses list required for the auth_ip_addr function.

This is mostly necessary for PPP in server mode to prevent the peer to
use the IP address it wants instead of the one we want, which is
currently allowed.

Rewrite auth_ip_addr in a simple way where we forbid PPP peer to use
loopback net, a multicast address or a reserved class address. Added
to that we consider that PPP in server mode with peer required to
authenticate must provide the peer IP address, reject any IP address
wanted by peer different than the one we wanted. This is actually
an allowed addresses "list" of one entry that follows what is done
in the unused auth_ip_addr function.

PPP, IPCP: remove obvious FIXME

No-op. This is now unused code and it is pretty self explanatory what
int_option do; it checks that passed parameter is an unsigned integer.

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")

Cleanup hton*/ntoh* function handling and platform abstraction
Let lwip use functions/macros prefixed by lwip_ internally to avoid naming clashes with external #includes.
Remove over-complicated #define handling in def.h
Make functions easier to override in cc.h. The following is sufficient now (no more LWIP_PLATFORM_BYTESWAP):
#define lwip_htons(x) <your_htons>
#define lwip_htonl(x) <your_htonl>

doxygen updates - include IPv6 in documentation. Exclude include/netif/ppp/polarssl.
Convert TODO -> @todo

PPP, move protocols initialization from ppp_clear to ppp_new

What protocols init functions are meant to is to be called once to set
the default configuration before user specific configuration is set.

Until now, we reset to the default configuration just before
reconnecting, thus without allowing any time frame to let users change
it. That was fine until one user asked to be able to do that.

This change move protocols init functions calls from ppp_clear to
ppp_new, meaning user configuration is not overwritten anymore.

PPP: Use LWIP_ARRAYSIZE at appropriate places

Use LWIP_ARRAYSIZE to simplify the code.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Sylvain Rochet <gradator@gradator.net>
[Sylvain Rochet <gradator@gradator.net>: added missing casts]
Signed-off-by: Sylvain Rochet <gradator@gradator.net>

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

PPP: more const and mixed u_char/char types fixes

PPP: fix constness in PPP related files when PRINTPKT_SUPPORT is enabled

PPP, sifnpmode() is only useful if on demand is supported, build out if not

We don't support PPP on demand, don't build sifnpmode() which is only
useful for on demand if on demand is not supported.

PPP, removed unnecessary memset()

Everything is cleared in ppp_clear(), we don't need to clear all
structures twice.

PPP, place print packet debug codenames in ROM

PPP, IPCP, removed proxy ARP support

PPP, IPCP, removed WINS support

PPP, IPCP, fully removed DNS support from IPCP if LWIP_DNS is disabled

PPP, IPCP, fully removed VJ support from IPCP if VJ_SUPPORT is disabled

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

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, 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, Removed (*datainput) from struct protent if not used

Data input is only used by CCP and ECP, which are not supported at this time,
remove this entry from struct protent to save some flash.

PPP, CORE, Removed useless enabled_flag from struct protent

Our struct protent are const everywhere to save RAM, enable/disable
flag on a const struct is useless, saving some flash, removed.

PPP, from PPPD upstream, Eliminate some unnecessary ifdefs

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

use u32_t instead of u_int32_t

The style u_int32_t is not used anywhere else in the project, and is not
supported by the C standard, now using lwIP u32_t type. It was introduced
in 25e398a.

fixed bug #43235, cleared compiler warnings when using gcc with -Wextra option

PPP, from PPPD upstream, accept IPCP ConfAck packets containing MS-WINS options

pppd: Accept IPCP ConfAck packets containing MS-WINS options

Since last week I'm seeing IPCP negotiations going like this (and
eventually failing) when connecting to my ISP:

Jul 11 20:03:25 * pppd[4833]: sent [IPCP ConfReq id=0x2 <addr 0.0.0.0> <ms-dns1
0.0.0.0> <ms-dns2 0.0.0.0>]
Jul 11 20:03:26 * pppd[4833]: sent [IPCP ConfReq id=0x2 <addr 0.0.0.0> <ms-dns1
0.0.0.0> <ms-dns2 0.0.0.0>]
Jul 11 20:03:26 * pppd[4833]: rcvd [IPCP ConfNak id=0x2 <addr 10.167.246.198>
<ms-dns1 213.162.69.1> <ms-dns2 213.162.69.169> <ms-wins 124.6.168.55> <ms-wins
17.17.17.17>]
Jul 11 20:03:26 * pppd[4833]: sent [IPCP ConfReq id=0x3 <addr 10.167.246.198>
<ms-dns1 213.162.69.1> <ms-dns2 213.162.69.169> <ms-wins 124.6.168.55> <ms-wins
17.17.17.17>]
Jul 11 20:03:26 * pppd[4833]: rcvd [IPCP ConfAck id=0x3 <addr 10.167.246.198>
<ms-dns1 213.162.69.1> <ms-dns2 213.162.69.169> <ms-wins 124.6.168.55> <ms-wins
17.17.17.17>]
Jul 11 20:03:27 * pppd[4833]: sent [IPCP ConfReq id=0x3 <addr 10.167.246.198>
<ms-dns1 213.162.69.1> <ms-dns2 213.162.69.169> <ms-wins 124.6.168.55> <ms-wins
17.17.17.17>]
...

with the last two lines repeating until the IPCP error limit is
reached. As you can see, the peer added two extra fields in the
ConfNak reply. This is allowed, and indeed the following sent
ConfReq packet reflects this. However, when the ConfAck packet
is received, pppd discards it as invalid, because of the ms-wins
fields.

This fixes it.

PPP, adding const pragma to FSM callbacks, saving about 350 bytes in .data segment

PPP, adding const pragma to struct protent, saving about 200 bytes in .data segment

PPP, renamed all functions using common names in utils.c that can conflict with lwIP user code during link operation

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

improved PPP default interface management, added ppp_set_default() API call

some buggy compiler get confused with duplicated labels used in enum tcp_state and fsm.h, prepending PPP's ones

replaced u_int{8,16,32}_t to lwIP u{8,16,32}_t types

added padding to compiler generated bitfield, this is seen as best practice,
maybe it helps buggy compilers

removed bool type, replaced by u8_t

moved back temporarily moved structure definitions from various headers to ppp.h during unit to ppp_pcb transition

no more pcb->unit, new user selectable pcb->num for debugging purpose (like netif does)

IPCP global variables moved to ppp_pcb

removed fsm->unit

protent prototype switched from unit to ppp_pcb

IPCP and LCP structures moved to ppp_pcb

auth.c functions now use ppp_pcb* as first argument

started the unit to ppp_pcb replacement

renamed ppp_control to ppp_pcb, replaced unit number to ppp_pcb in all ppp.h declared functions

moved ppp_settings to ppp_control, improved PPP API to really allow multiple PPP sessions

using PPP_DEBUG instead of debug global variable

unused ifunit global variable removed

dns server support is done, clearing FIXME entries

re-enabled DNS support

setting default route by default

cleaned depreacted __P() and __V() macros, removed the legacy varargs.h header

disabled all plugins hooks

removed CamelCase in ppp.c and ppp_impl.h, added compat macro in ppp.h (but disabled for now)

ppp_impl.h is back!

don't build any PPP file if PPP support is disabled

removed all system headers except the strict minimum

make it build with avr32-gcc

Disabled Unix-centric non necessary include files

Changed some include paths

Removed all printf() I put there and there for debugging.

It builds with the avr32 gcc toolchain, meaning we removed
all the pppd code requiring a unix base.

fixed most PPP compilation warnings with -pedantic

fixed all PPP compilation warnings with -Wall

removed pppd.h and ppp.c, renamed pppmy.c to ppp.c and pppmy.h to ppp.h

added pppmy.h in all .c files to easily find conflicts

resolve conflit, ipcp.c defines ip_ntoa() which is already defined by lwIP, disabled ipcp.c::ip_ntoa() and using lwIP one

PPP statistics optional (non working) compile time option added

PPP notifier support is now a compile time option

However, as of now, the notify() function is empty, so it requires
some work if someone want to use it.

The notify feature allows someone to be able to follow the
state of the PPP stack (auth ok, ipcp up, initialise, ...), this
is like the callback feature set by pppOverEthernetOpen() and others,
but with more details.

removed set/getenv functions

removed more protent fields only used by print packets functions

print packet functions are now optional

demand support is now a compile-time option

Obviously, it requires some wiring to know if there is new activity
on a not-yet established PPP interface with the default route
already set.

I don't think any lwIP user will ever need that, all should know
when to bring the link up and down.

removed pathnames.h and pidfile support

replaced BCOPY to lwip-MEMCPY

more and more ppp options removal

disabled almost all PPP options strings and support as well as useless file-based auth code

removed run_program() support

fixed demand_rexmit() with new IP addr, maybe we will never support demand or drop it, but it is already patched just in case

added IPCP no/replace default route option from Debian patches, I like the idea

Early development stage of an attempt to port PPPd 2.4.5 to lwIP.

PPPoE works, PPPoS code is not ported at all.

I am using the RP-PPPoE server to do my tests using the following
configuration:

$ cat /etc/ppp/pppoe-server-options
debug
login
lcp-echo-interval 10
lcp-echo-failure 10
ms-dns 192.168.4.130
ms-dns 192.168.4.231
netmask 255.255.255.0
defaultroute
noipdefault
usepeerdns

$ cat /etc/ppp/allip
192.168.4.1-200

$ pppoe-server -C isp -L 192.168.4.254 -p /etc/ppp/allip -I tap0

Plus the usual auth-lines in /etc/ppp/pap-secrets and
/etc/ppp/chap-secrets .

And the unix port minimal "echo" project slightly modified to use
the "tcpip" API, so with threads, which I am going to commit with
NO_SYS as a -Dmacro.

It still use some of the linux'ism, such as syslog() and crypt(),

I do not want to drop the syslog() supports at the moment, this is
pretty useful to debug, and we may just convert the way the syslog() is
done to provide a trace feature to our PPP users, as a compile-time
option.

splitted ppp.h to an internal and external header file to get a clear separation of which functions an application or port may use (task #11281)

PPP: use LWIP_DEBUGF() instead of ppp_trace()

Added debug output and missing casts

Cleanly separate the portability file inet.h and its contents from the stack: moved htonX- functions to def.h (and the new def.c - they are not ipv4 dependent), let inet.h depend on ip_addr.h and not the other way round. This fixes bug #28732.

bug #26523: Compiler Warnings

Reorganised PPP source code from ucip structure to pppd structure to easily compare our code against the pppd code (around v2.3.1)

Various small improvements from patch #6965 (removed _inet_ntoa, set PPP netif down before removing, change log message and comment)

Minor changes in PPP (coding style, tabs, idents...)

First fix for bug #21664 "PPP code is broken".

Ongoing fix to patch #5822: converted more statements like (void)arg; into LWIP_UNUSED_ARG(arg);

Dependencies on C library memset() etc., so include <string.h>.

fix inet_ntoa prototype to be standard, and fix ppp code that used the non-standard version

An overriden merge from DEVEL to main was needed as small changes had been made to main.

sio and PPP updates from Marc

Cleanups in PPP: C++ comments removed, make it compile for unixsim too. Does not work yet only compiles

add PPP stack from Marc. Work in progress