Older compilers (GCC 4.6) don't like variables with the same name as
global functions:
lwip/src/netif/ppp/lcp.c: In function 'lcp_received_echo_reply':
lwip/src/netif/ppp/lcp.c:2685:11: error: declaration of 'magic' shadows a global declaration [-Werror=shadow]
lwip/src/include/netif/ppp/magic.h:101:7: error: shadowed declaration is here [-Werror=shadow]
magic.h contains a function named magic(), so rename the variable.
It used to be this way because the original implementation was close to
the hardware and used a free running 16 bits timer so it was necessary.
Currently what it is only doing is removing potential entropy we might
get from upper bits, that's a bad idea.
Jiffies isn't really a humanly readable value and it means the default
PPP_MAXIDLEFLAG period depends on the platform "jiffies" frequency,
which isn't nice.
Change PPP_MAXIDLEFLAG to use ms instead of jiffies, the current
PPP_MAXIDLEFLAG default (100 ms), looks like a sane value and is
left unchanged.
The overall lwIP design on data flows (netif,udp,tcp) is to use a user
defined callback to get data from stack and a static function to send
data to stack, which makes perfect sense. The SIO port was an exception,
the PPP stack never really used the SIO port by only using the
sio_send() function (and the ignominious sio_read_abort() function a
while back).
The way the SIO port is currently designed adds a tight coupling between
the lwIP port and the user code if the user need to do specific user
code if the current uart used is the PPPoS uart, which is not nice,
especially because all the lwIP stack is quite clean at this subject.
While we are at stabilizing the PPP API, change this behavior before
it's too late by replacing the static sio_write() calls to a user
defined callback.
Added the random seed already used without PPP_MD5_RANDM
as an entropy source when PPP_MD5_RANDM feature is enabled.
(And a little bit of code cleaning for both)
If LWIP_RAND() is available, it is used instead of libc srand()/rand()
if PPP_MD5_RANDM is disabled and it is added as a source of randomness
if PPP_MD5_RANDM is enabled.
A disabled PPP_MD5_RANDM should not be used when challenge are used, but
anyway, improved magic_randomize() so magic_randomseed is not equals to
sys_jiffies() which is pretty useless because that's fully predicable.
The only API difference with and without the PPP_MD5_RANDM support is the
availability of the random_bytes() function. Added a random_bytes()
function on top of magic() when PPP_MD5_RANDM support is not enabled,
thus allowing builds for both cases.
PPP_MD5_RANDM is still enabled by default (it was mandatory) if a protocol
using encryption is enabled, such as CHAP, EAP, or L2TP auth support.
There is no point of calling magic_randomize() for each pppos_input()
call, making magic_randomize() potentially called for each serial input
byte which is quite a bad idea since magic_randomize() is quite
intensive in processing time (MD5 computation) compared to HDLC frame
parsing. There is no entropy added when being called for each input byte
rather than for each valid input packet because byte input is a
monotonic event at the packet level. Well, if packet arrival time is a
valid entropy source even so, which I doubt a lot, but we don't really
have anything else and we really need random for PPP authentication
layers.
Drop input/output packets if we couldn't find a decompressor/compressor,
it can't really happen because we only negotiate what we are able to
compress/decompress, but for the sake of code consistency it makes much
more sense to do so.
We used to modify in place the packet payload during encryption, it works
well for UDP and ICMP but TCP stack requires that we don't change the
packet payload, therefore we now copy the whole packet before encryption.
When PPP is used over a link which does not guarantee packet ordering,
we might get late MPPE packets. This is a problem because MPPE must be
kept synchronized and the current implementation does not drop them and
rekey 4095 times instead of 0, which is wrong.
In order to prevent rekeying about a whole count space times (~ 4095
times), drop packets which are not within the forward 4096/2 window and
increase sanity error counter.
Check tot_len for ZLB instead of len, it might happens we are just
between 2 pbuf, although almost impossible.
Check buffer is at least 2 byte long before checking address & flags
header.
PBUF_LINK_ENCAPSULATION_HLEN support was introduced by 6ef7563f and
missed the fact that header size calculation/reservation using
computation like PBUF_LINK_HLEN + PBUF_IP_HLEN + ... are used all over
the source code. Hopefully fixed all of them.
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.
We need to know which methods were chosen when CCP is up, this used to be done
using ccp_test() which we are in the process of removing.
Using non-existing method 0 instead of -1 in CCP for unset method, allowing
type change from s16_t to u8_t for method.
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.
MSCHAP was written the old-way, with all functions declared non static in
header, independent of their local or global scope status. Same for local
constants. Reworked in a more mordern way.
We are going to need ppp_pcb* in MSCHAP and MSCHAPv2 for MPPE for
int mppe_keys_set, u_char mppe_send_key and u_char mppe_recv_key
which are currently global variable which must be moved to ppp_pcb.
Removing a bit of redundancy and previous artefact of a generic kernel
interface. Exporting mppe_init() instead of mppe_comp_init() plus
mppe_decomp_init().
We are going to use statically allocated struct ppp_mppe_state through PPP PCB,
removed now useless mppe_alloc() and mppe_free().
Merged mppe_alloc() key copy to mppe_init().
ccp_test() is not only used to test kernel support, but also to set MPPE keys,
we will change that further, but for now, re-add the necessary ccp_test()
Our PPP stack deals with packet without address and control byte nor 2-byte
protocol field, improved mppe_compress() so we don't have to worry about
them.
Our PPP stack deals with packet without address and control byte nor 2-byte
protocol field, improved mppe_compress() so we don't have to worry about
them.
If LWIP_IPV4 is true but PPP_IPV4_SUPPORT is false, we need
a dummy ppp_netif_output_ip4() callback because we don't have
a netif_null_output_ip4() by default like we have for IPv6 with
netif_null_output_ip6().
