gbproxy: Parse additional IMSI/PTMSI/TLLI fields

This adds parsing support for the following messages:
  - Attach Request: IMSI/PTMSI
  - Identity Response: IMSI/PTMSI
  - BSSGP: Optional TLLI IE
  - BSSGP/PAGING_PS: PTMSI

A new new_ptmsi_enc field is added for newly assigned PTMSI in
SGSN->BSS messages (instead of ptmsi_enc). The ptmsi_enc field is now
used for informational PTMSI IE in messages.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/gbproxy/gbproxy_test.ok b/openbsc/tests/gbproxy/gbproxy_test.ok
index 036c4a3..ee67c33 100644
--- a/openbsc/tests/gbproxy/gbproxy_test.ok
+++ b/openbsc/tests/gbproxy/gbproxy_test.ok
@@ -1639,6 +1639,30 @@
 
 result (ATTACH REQUEST) = 79
 
+PROCESSING IDENT REQUEST from 0x05060708:32000
+00 00 10 02 00 bb c5 46 79 00 50 20 16 82 02 58 0e 89 41 c0 01 08 15 01 ff 6c ba 
+
+CALLBACK, event 0, msg length 23, bvci 0x1002
+00 00 10 02 00 bb c5 46 79 00 50 20 16 82 02 58 0e 89 41 c0 01 08 15 01 ff 6c ba 
+
+NS UNITDATA MESSAGE to BSS, BVCI 0x1002, msg length 23 (gprs_ns_sendmsg)
+MESSAGE to BSS at 0x01020304:1111, msg length 27
+00 00 10 02 00 bb c5 46 79 00 50 20 16 82 02 58 0e 89 41 c0 01 08 15 01 ff 6c ba 
+
+result (IDENT REQUEST) = 27
+
+PROCESSING IDENT RESPONSE from 0x01020304:1111
+00 00 10 02 01 bb c5 46 79 00 00 04 08 88 11 22 33 40 50 60 75 30 00 80 0e 00 11 01 c0 0d 08 16 08 11 12 13 14 15 16 17 18 b7 1b 9a 
+
+CALLBACK, event 0, msg length 40, bvci 0x1002
+00 00 10 02 01 bb c5 46 79 00 00 04 08 88 11 22 33 40 50 60 75 30 00 80 0e 00 11 01 c0 0d 08 16 08 11 12 13 14 15 16 17 18 b7 1b 9a 
+
+NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 40 (gprs_ns_sendmsg)
+MESSAGE to SGSN at 0x05060708:32000, msg length 44
+00 00 10 02 01 bb c5 46 79 00 00 04 08 88 21 63 54 40 50 60 75 30 00 80 0e 00 11 01 c0 0d 08 16 08 11 12 13 14 15 16 17 18 b7 1b 9a 
+
+result (IDENT RESPONSE) = 44
+
 PROCESSING ATTACH ACCEPT from 0x05060708:32000
 00 00 10 02 00 bb c5 46 79 00 50 20 16 82 02 58 13 99 18 b3 43 2b 25 96 62 00 60 80 9a c2 c6 62 00 60 80 ba c8 c6 62 00 60 80 00 0a 82 08 02 0d 88 11 12 13 14 15 16 17 18 00 81 00 0e 9e 41 c0 05 08 02 01 49 04 21 63 54 40 50 60 19 cd d7 08 17 16 18 05 f4 ef e2 b7 00 42 67 9a 
 
@@ -1701,7 +1725,7 @@
 
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
-    RAID patched              (BSS ): 7
+    RAID patched              (BSS ): 8
     RAID patched              (SGSN): 2
     APN patched                     : 3
     Attach Request count            : 1
@@ -1734,7 +1758,7 @@
 
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
-    RAID patched              (BSS ): 8
+    RAID patched              (BSS ): 9
     RAID patched              (SGSN): 2
     APN patched                     : 3
     Attach Request count            : 1
@@ -1779,7 +1803,7 @@
 
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
-    RAID patched              (BSS ): 11
+    RAID patched              (BSS ): 12
     RAID patched              (SGSN): 3
     APN patched                     : 3
     Attach Request count            : 1
@@ -1813,7 +1837,7 @@
 Gbproxy global:
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
-    RAID patched              (BSS ): 12
+    RAID patched              (BSS ): 13
     RAID patched              (SGSN): 3
     APN patched                     : 3
     Attach Request count            : 1
@@ -1851,7 +1875,7 @@
     Patch error: no peer            : 1
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
-    RAID patched              (BSS ): 13
+    RAID patched              (BSS ): 14
     RAID patched              (SGSN): 3
     APN patched                     : 3
     Attach Request count            : 1