The function now takes a struct msc_config and returns true if that MSC is
connected. The vty command show msc connection now shows a line per connected
MSC.
In bsc_nat.c where osmo-bsc_nat previously hung up on a BSC connection if the
(one) MSC was not connected it now checks for the default MSC connection.
Change-Id: I95fbe1b8ad6621aba9b4bd6b581abfde0cb31fd0
Ticket: SYS#3208
Sponsored-by: On-Waves ehf.
Add new kitchen sink openbsc/utils.h and libcommon/utils.c to make three so far
static functions public (so I can use them in the upcoming OAP code).
A place to put them could have been the gprs_utils.h, but all general functions
in there have a gprs_ prefix, and todo markings to move them away. All other
libcommon headers are too specific, so I opened up this kitchen sink header.
Replace the implementation of encode_big_endian() with a call to
osmo_store64be_ext(). See comments.
Apply the change in Makefiles and C files.
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.
Move the filter methods to the filter module. This is
still only usable for the NAT and the _dt/_cr filter
routines need to move back to the bsc_nat in the long
run.
On DT messages we directly write into the tracked SCCP
connection. This means "imsi" will always be NULL at
this check. Change the code to use con->imsi
Fixes: Coverity CID 1293151
I used strdup in case the data would not be valid from after
the call to getopt and this creates a potential leak if a user
is specifying multiple configuration files. If I depend on the
fact that the string is a pointer into the argv[] array I can
kill the strdup and fix the unlikely leak.
Fixes: Coverity CID 1206578
The code in the BSC/NAT called ipaccess_rcvmsg_base without
checking if the protocol is IPA. This lead the BSC to respond
to SCCP messages with an "ID ACK". From a quick look neither
the code of ipaccess_rcvmsg_base in OpenBSC nor the copy of
libosmo-abis ever checked the protocol header. So this code
has been wrong since initially being created in 2010.
Coverity complains about checking connection->cfg in
bsc_close_connection() at one place but not at the second.
This patch fixes this by adding a check before accessing cfg when
generating the 'partial message' log message.
Fixes: Coverity CID 1195180
Sponsored-by: On-Waves ehf
The log message lacked a lot of context. A SCCP connection is
created on behalf of a configured BSC. This way we should be
able to always list this information.
The old ipa_msg_recv() implementation didn't support partial receive,
so IPA connections got disconnected when this happened.
This patch adds the handling of the temporary message buffers and uses
ipa_msg_recv_buffered().
It has been successfully tested by jerlbeck with osmo-nitb and
osmo-bsc.
Ticket: OW#768
Sponsored-by: On-Waves ehf
In case of the RLSD coming from the MSC we are patching the address
in-situ but for local calls set con = NULL. We then answered the RLSD
with the wrong reference and the MSC kept on trying.
Assign a static name to a MSC Connection and use it. In case there
are multiple connections we can now more easily identify them.
This is only used for the NAT right now, the BSC could start to
name the various MSC connections too.
* It is a trie. The max depth of the trie is the length of the
longest prefix. The lookup is O(lookuped_prefix), but as the prefix
length is limited, the lookup time is constant.
* Each node can hold the entire prefix, has place for the rewrite
rule with up to three digits.
* A trie with 20k entries will take about 3MB ram.
* Filling the trie 100 times takes ~800ms on my i7 laptop
* 10.000.000 lookups take 315ms.. (for the same prefix).
* 93/99 lines are tested, 6/6 functions are tested, 49 of 54 branches
are tested. Only memory allocation failures are not covered
* A late addition is to handle the '+' sign and to increase the number
of chars in the rewrite prefix. The timing/line coverage has not
been updated after this change.
Coverity pointed out that this code is logically dead. Quickly
judging the code we will forward the RSLD message anyway. Remove
the code for now and next time I work on the NAT/USSD bridge I
will have a look at the flow of the RLSD messages.
Fixes: Coverity CID 1042327
Find the Cell Identifier from the Complete Layer3 Information and
store it for future reference. We could begin to verify that the
LAC/CI used really belongs to the BSC.
The name sccp_connection is used in the osmo-sccp code, sccp_connections
was used in the NAT for tracking a sccp_connection. Rename it so it is
obvious that the struct belongs to the nat.
The rename was done with sed:
$ sed -i s,"struct sccp_connections","struct nat_sccp_connection",g \
include/openbsc/*.h src/osmo-bsc_nat/* tests/*/*
Daniel Willmann
Jacob Erlbeck
Neels Hofmeyr
Harald Welte