Commit Graph

23 Commits

Author SHA1 Message Date
Jacob Erlbeck 2e2650f8f3 gprs: Parse PTMSI and update TLLI accordingly
This commit adds code to parse the PTMSI in network originated
messages

  - Attach Accept,
  - Routing Area Update Accept, and
  - P-TMSI Reallocation Command (see below)

to keep track of the TLLI identifying the LLC connection.

The P_TMSI Realloc Command specific code is not being tested yet, so
a corresponding notice is logged when such a message will be
received.

NOTE:
  The gbproxy will lose the TLLI when the MS doesn't receive/use
  the message (normally the SGSN remembers the old TLLI for some time
  to avoid this kind of problem). If this happens the MS will
  probably restart the procedure and the network will have to answer
  again eventually using one of the above messages which will
  re-associate the IMSI with the TLLI before the MS can send a
  PDP Context Request message.

Ticket: OW#1192
Sponsored-by: On-Waves ehf
2014-07-22 17:11:57 +02:00
Jacob Erlbeck b138106423 gprs: Add TLV parse functions
This adds a set of function that parse a single tlv, lv, tv, or v
encoded information element. They are complementary to the *_put
functions defined in libosmocore's tlv.h file. The functions update
the data and data_len fields unless they are a 'match' function and
the tag field doesn't match.

Sponsored-by: On-Waves ehf
2014-07-22 17:08:10 +02:00
Jacob Erlbeck 040b4012a7 gprs: Fix TLLI cache size computation
Currently the enabled_tllis_count field isn't always decremented when
an element is removed from the TLLI cache list.

This patch adds the missing update and also adjusts the counter
accordingly.

Sponsored-by: On-Waves ehf
2014-07-22 17:05:16 +02:00
Jacob Erlbeck aa3e334608 gprs/test: Rearrange for PTMSI parsing
Add TLLI cache output to gbprox_dump_peers() to include this info
into the test output.

Separate RA Update Req message handling from Attach Request handling.

Note: There is no test case for the P-TMSI Reallocation Command yet.

Sponsored-by: On-Waves ehf
2014-07-22 17:03:23 +02:00
Jacob Erlbeck 25049b93b1 gprs: Add counters related to LLC layer patching
This commit adds the following counters:

  - attach-reqs:   Number of Attach Request messages
  - attach-rejs:   Number of Attach Reject messages
  - tlli-cache:    Size of the TLLI cache

Sponsored-by: On-Waves ehf
2014-07-22 17:02:43 +02:00
Jacob Erlbeck 7c101d922e gprs: Track IMSI/TLLI to control APN patching
This patch adds IMSI/TLLI connection tracking and uses it to control
APN patching based on the IMSI. TLLI entries can expire based on age
and/or by limiting the TLLI list size.

VTY config-gbproxy:
  no core-access-point-name                   disable APN patching
  core-access-point-name none                 remove APN if present
  core-access-point-name APN                  replace APN if present
  core-access-point-name none match-imsi RE   remove if IMSI matches
  core-access-point-name APN match-imsi RE    replace if IMSI matches
  tlli-list max-age SECONDS                   expire after SECONDS
  no tlli-list max-age                        don't expire by age
  tlli-list max-length N                      keep N entries only
  no tlli-list max-length                     don't limit list length

RE is an extended regular expression, e.g. ^12345|^23456

Ticket: OW#1192
Sponsored-by: On-Waves ehf
2014-07-22 16:56:33 +02:00
Jacob Erlbeck 006c038212 gprs: Store gbproxy patching state per peer
Currently, all patching state is stored globally in the gbproxy. Thus
the feature cannot be used safely with a concentrating gbproxy (NAT).

This patch moves the state and relevant counters to the gbprox_peer
structure. It adds code to resolve the corresponding peer when
packets are received by looking at BVCI, NSEI, and BSSGP IEs (BVCI,
RAI/LAI/LAC) when the peer is not passed to the
gbprox_patch_bssgp_message() function.

Test cases are also added for the SGSN->BSS case including test cases
with invalid identifiers.

Note that this patch should make it possible to use RAI patching at a
NAT gbproxy as long as the messages are not encrypted.

Ticket: OW#1185
Sponsored-by: On-Waves ehf
2014-07-22 16:53:41 +02:00
Jacob Erlbeck cf02eb1b20 gprs/test: Add Detach messages to test
This patch adds a Detach Request (MO) / Detach Accept sequence to the
test, followed by another (here invalid) Act PDP Context Req which
should be APN patched.

Sponsored-by: On-Waves ehf
2014-07-22 16:19:57 +02:00
Jacob Erlbeck 1166974bca gprs/test: Added GMM Info and fixed TLLI
Add a DTAP GMM Information message with an IMSI in the BSSGP header
to enable the association between IMSI and TLLI.

The TLLI of the Routing Area Update messages is set to foreign.

Sponsored-by: On-Waves ehf
2014-07-22 16:18:40 +02:00
Jacob Erlbeck 736852825a gprs: Add APN patch support for LLC/GSM messages
Patch the APN in every 'Activate PDP Context Request' message to the
value given by the 'core-access-point-name' command. If the command is
given without an APN, the whole APN IE will be removed. If the
command is being prefixed by a 'no', the APN IE remains unmodified.

The patch mode 'llc-gsm' is added to selectively enable the patching
of LLC session management messages. This is enabled implicitely by
the patch mode 'llc'.

Note that the patch mode should not be set to a value not enabling
the patching of LLC GSM messages ('llc-gsm', 'llc', and 'default' are
sufficient to patch 'Activate PDP Context Request' messages).

Ticket: OW#1192
Sponsored-by: On-Waves ehf
2014-07-22 16:07:01 +02:00
Jacob Erlbeck 91fb680236 gprs: Add MCC/MNC patch support for LLC/GMM messages
This patch extends the BSSGP patch code to also patch LLC information
elements along with MCC/MNC patching support for the following messages:

- Attach Request
- Attach Accept
- Routing Area Update Request
- Routing Area Update Accept
- P-TMSI reallocation command

Note that encrypted packets will not be patched.

Ticket: OW#1185
Sponsored-by: On-Waves ehf
2014-07-22 16:05:59 +02:00
Jacob Erlbeck 67a4445675 gprs: Implement BSSGP MCC/MNC patching
This adds a feature to patch the BSSGP MNC/MCC fields of messages going
to and coming from the SGSN. To enable this feature, the gbproxy's
VTY commands 'core-mobile-country-code' and/or
'core-mobile-network-code' must be used. All packets to the SGSN are
patched to match the configured values. Packets received from the
SGSN are patched to the corresponding values as last seen from the BSS
side.

Note that this will probably not work with a gbproxy used for several
BSS simultaneously.

Note also, that MCC/MNC contained in a LLC IE will not be patched.

Ticket: OW#1185
Sponsored-by: On-Waves ehf
2014-07-22 16:04:54 +02:00
Jacob Erlbeck ff0d65aaf6 gprs/test: Make test output more readable
This patch makes a few changes to improve readability:

- change the sendto() hexdump to start with NS instead of BSSGP
- use more specific message descriptions instead of 'UNITDATA'
- add a title line per test

Sponsored-by: On-Waves ehf
2014-07-22 15:48:53 +02:00
Jacob Erlbeck 7fb42dbd27 gprs/test: Add additional gbproxy tests
This adds a test case with several messages to test BSSGP patching.
New messages:

- BSSGP/DTAP Attach Request
- BSSGP/DTAP Attach Accept
- BSSGP/DTAP Routing Area Update Request
- BSSGP/DTAP Routing Area Update Accept
- BSSGP/DTAP Activate PDP Context Request
- BSSGP SUSPEND
- BSSGP SUSPEND ACK

Sponsored-by: On-Waves ehf
2014-07-07 15:06:12 +02:00
Jacob Erlbeck 8f50359ebf gprs: Use area terms LAI/RAI as defined in GSM 03.03
Currently the terms 'Routing area code' (RAC) and 'Location area
code' (LAC) are used in several places where 'Routing area
identification' (RAI) or 'Location area identification' (LAI) are
meant in fact.

This patch replaces RAC/LAC by RAI/LAI and 'code' by 'identification'
at these places.

Note that RAI := MCC MNC LAC RAC, and LAI := MCC MNC LAC (see GSM
03.03, sections 4.1 and 4.2).

Sponsored-by: On-Waves ehf
2014-06-15 19:23:38 +02:00
Jacob Erlbeck def0391ec5 gprs/test: Use valid MCC/MNC for BVC RESET
The code currently uses an encoded sequence of (hex) 10 20 30 40 50
60 as RAI, for which no bijective mapping to the set of
representations MCC-MNC-LAC-RAC exists.

This patch changes the hard-coded RAI to 11 22 33 40 50 60 which maps
to 112-332-16464-96 (and vice-versa).

Sponsored-by: On-Waves ehf
2014-06-04 16:20:46 +02:00
Jacob Erlbeck 64cb924634 gbproxy: Fix handling of NSEI changes
The gbproxy looses NSEI changes on BVC_RESET and then tries to send
later messages to the wrong (not longer existing) destination.

This patch fixes this by updating the peer's nsei field on BVC_RESET.

Ticket: OW#874
Sponsored-by: On-Waves ehf
2013-10-24 18:02:38 +02:00
Jacob Erlbeck 72b401f33d gbproxy: Add test for NSEI and NSVCI changes
This checks the behavior of the gbproxy when the BSS peer changes the
NSEI and the NSVCI. It also tests BVC_RESET and other UNITDATA
messages after these changes between BSS and SGSN and vice versa (via
the gbproxy).

Ticket: OW#874
Sponsored-by: On-Waves ehf
2013-10-24 18:02:36 +02:00
Jacob Erlbeck f0f63a4113 gbproxy: Reject SGSN UNITDATA messages with an invalid BVCI
Currently such messages lead to a creation of a new peer with the
SGSN's NSEI, which results in echoing the message back to the SGSN.

This patch modifies this by sending a STATUS response (invalid BVCI)
instead back to the SGSN.

Sponsored-by: On-Waves ehf
2013-10-19 12:10:24 +02:00
Jacob Erlbeck da890c7733 gbproxy: Test invalid BVCI from SGSN
This adds a test with a UNITDATA SGSN message that is addressed to an
invalid (unknown) BVCI. The test shows, that the message is echoed to
the SGSN.

Sponsored-by: On-Waves ehf
2013-10-19 12:10:21 +02:00
Jacob Erlbeck bc555742aa gbproxy: Add global and per peer counters
This adds counters that are incremented when errors are detected.
It also modifies the VTY command 'show gbproxy' so that
'show gbproxy stats' shows the counters.

Sponsored-by: On-Waves ehf
2013-10-19 12:10:19 +02:00
Jacob Erlbeck 2082afa76e gbproxy: Extended test program to simulate SGSN, too
This adds a simulation of the SGSN side of the Gbproxy. The VC is set
up correctly and several combinations of BSSGP messages are sent.

Sponsored-by: On-Waves ehf
2013-10-19 12:10:13 +02:00
Jacob Erlbeck 51a869c80c gbproxy: Add test program to test gbproxy message handling
This program tests the gbproxy implementation by passing NS messages
to a modified gbproxy that dumps the resulting messages, signals, and
state.

It focusses on testing abnormal situations like port changes.

Ticket: OW#874
Sponsored-by: On-Waves ehf
2013-10-15 15:10:22 +02:00