We just link to libosmovty and if it requires crypt internally it
needs to link to that (and not us). This looks like a left-over
from when we moved the VTY code out of OpenBSC
We don't need to consume all the entropy of the kernel but can
use libcrypto (OpenSSL) to generate random data. It is not clear
if we need to call RAND_load_file but I think we can assume that
our Unices have a /dev/urandom.
This takes less CPU time, provides good enough entropy (in theory)
and leaves some in the kernel entropy pool.
We are using the token to find the right bsc_config and
then we can use the last_rand of the bsc_connection to
calculate the expected result and try to compare it with
a time constant(???) memcmp.
Check if the NAT has sent 16 bytes of RAND and if a key
has been configured in the system and then generate a
result using milenage. The milenage res will be sent and
noth the four byte GSM SRES derivation.
Generate 16 byte of random data to be used for A3A8 by
the BSC in the response. We can't know which BSC it is
at this point and I don't want to send another message
once the token has been received so always send the data
with an undefined code. The old BSCs don't parse the
message and will happily ignore the RAND.
/dev/urandom can give short reads on Linux so loop
around it until the bytes have been read from the kernel.
Instead of doing open/read/close all the time, open the
FD in the beginning and keep it open. To scare me even
more I have seen /dev/urandom actually providing a short
read and then blocking but it seems to be the best way
to get the random byes we need for authentication.
So one should/could run the cheap random generator on
the system (e.g. haveged) or deal with the NAT process
to block.
Unfortunately the basic structure of the response is broken.
There is a two byte length followed by data. The concept of
a 'tag' happens to be the first byte of the data.
This means we want to write strlen of the token, then we
want to write the NUL and then we need to account for the
tag in front.
Introduce a flag if the new or old format should be used.
This will allow to have new BSCs talk to old NATs without
an additional change. In the long run we can clean that up.
In case the token was not correct, just close the connection.
It is not clear that forcing a new TCP connection is going to
give us any extra security here. But with the upcoming auth
handling it does make sense to have both case look similar.
In the libfilter source code, which is built regardless of --enable-nat,
headers from libosmo-sccp were used, thus causing a build failure (see
below) when building without --enable-nat, and libosmo-sccp not being
installed (or being installed in a prefix not otherwise included in the
build).
The build fails like this:
In file included from ../../../src/libfilter/bsc_msg_filter.c:27:0:
../../../include/openbsc/bsc_nat_sccp.h:27:37: fatal error: osmocom/sccp/sccp_types.h: No such file or directory
As the includes seem not to be actually needed, this change fixes the
issue by just omitting them.
Running "make distcheck" failed trying to generate ".version" into the
read-only unpacked source directory. Actually shipping ".version" in the
tarball fixes that.
There was no context for the SCCP CREF message and this means
that the msc_con was a plain NULL pointer that was dereferenced
and the application would crash.
Use the new API to pass the incoming MSC Connection which sould
be used for the SCCP CREF message as context. The code has not
been fed with an actual SCCP CR message.
The loop was used to print all returned addresses but we can
simply pick the first one. This is fixing a coverity issue that
the loop will be executed eaxactly once (and that was on
purpose).
Simplify the code and just take the first element (which might
be NULL).
Fixes: Coverity CID#1302852
We can't do much in case the fd is failing to be registered.
There should be a timeout that is catching this and it might
be able to repair it self.
Fixes: Coverity CID#1302854
The code to do that doesn't belong to the control interface, so
abstract it out to a separate function gsm_bts_set_system_infos().
[hfreyther: Fix the coding style...]
In case the query for "hostname" will fail c-ares will append the
domain name of /etc/resolv.conf and query again. We don't want that
so claim we provide a list of domain names and then don't provide
any.
I didn't intend to have pushed the c-ares code to master yet.
For real networks we need to check if the requested APN string
is allowed and then resolve the GGSN address through DNS. There
are countries with two or three digit MNCs and one could either
try to keep a list of countries that have two/three digits or
just try both of them. I have opted for the later for the ease
of the implementation.
C-Ares doesn't allow to cancel a request so we will need to
have the MMCTX and the Lookup have different lifetimes. We simply
set ->mmctx to NULL in case the MMCTX dies more early.
The selected and verified apn_str will be copied into the out
parameter. In case no static APN/GGSN config is present and the
dynamic mode is enabled a request will be made.
c-ares is an asynchronous DNS resolver and we need it to
resolve the GGSN address. This is integrating the library
into our infrastructure. We will create and maintain a list
of registered FDs (c-ares is currently only using one of
them) and (re-)schedule the timer after events occurred.
When needing to do an asynchronous DNS query we need
to keep the TLV data around. So create a wrapper that
takes a copy of it and frees it after the call. I can
change the code to add an out parameter to decide if
the msgb should be freed or not.
Pick network failure in case the msgb could not be
cloned in the hope the MS will retry then.
A real SGSN will dynamically resolve the APN name into the
GGSN IP Address. This means that after we have collected all
information we need to start to resolve the GGSN and then
can continue.
This is a left-over from the initial system where no PDP
was provided by the system. For now if there is a subscr
attached and no PDP context provisioned. He is not allowed
to have a data connection.
Update the testcase to create the pdp list entry more
early with a wildcard and then change it to a specific
match.
Include the hlr-Number of the subscriber in the CDR. This is useful
for debugging and understanding which equipment was used during the
test. In contrast to the MSISDN the '+' is emitted as the number
must be in international format already.
Copy the hlr-Number into the sgsn_data and use it during
the purgeMS. There is no unit test that looks at the data
we send so I manually verified this by looking at the output.
Below is the output of the test that purges the subscriber.
<000f> gprs_subscriber.c:170 SUBSCR(123456789012345) Sending GSUP, will send: 0c 01 08 21 43 65 87 09 21 43 f5 09 07 91 83 61 26 31 23 f3
We have verified/selected the APN. Either based on the subscriber
data, a global APN match. But at least this SGSN has looked at
what the MS has asked for and then selected a matching GGSN.
Clear LAC/RAC with pre-defined value in the RAI.
3GPP 29.060 v7.17.0 section 7.3.1 page 23:
"The SGSN may include the Routeing Area Identity (RAI) of the
SGSN where the MS is registered. The MCC and MNC components shall
be populated with the MCC and MNC, respectively, of the SGSN
where the MS is registered. The LAC and RAC components shall be
populated by the SGSN with the value of 'FFFE' and 'FF',
respectively.”
Most SGSNs pass the IMEI(SV). We currently only enquire about
the IMEI and then pad the 'SV' with 1111b (thanks to the encoding
routine). Sadly it insists on always writing the length which
means we have to memmove the data around by a single octet.
Manually verified using the pcu-emu and looking at the trace
using wireshark.
Give the GGSN another opportunity to determine which tarif
to apply for the SGSN/subscriber. This code assumes tha the
RAN is a GERAN system but the assumption has been made in
other places as well.
For PDP context creation we always want to include the RAI
for the current mmctx. This might help commercial GGSNs to
determine which charging to apply.
The charging_id is provided by the GGSN. Copy it into the CDR
part of the data structure so it will remain present until after
the pdp context has been deleted.
Make it possible to set a filename to use for the CDR. By
default no CDR will be generated. Forbid to set the interval
of 0 seconds as this will cause a lot of work. Add a very
basic VTY test.
This is consuming the new signals and allows to install several
different CDR/observing/event/audit modules in the future. For
getting the bytes in/out the code would have had to undo what the
rate counter is doing and at the same time adding a "total" to
the ratecounter didn't look like a good idea, the same went for
making it a plain counter.
Begin writing the values one by one and open/closing a new FILE
for every log messages. This is not efficient but easily deals
with external truncation/rotation of the file (no fstat for and
checking the links and size). As usual we will wait and see if
this is an issue.
Add some new members to our PDP context structure to see what it
is about.
Holger Hans Peter Freyther