gbproxy: Keep tlli_info after detach

Currently a tlli_info entry is deleted when the TLLI gets invalidated
by a Detach message.

This patch introduces the possibility to keep tlli_info entries in
the list. Those entries then have cleared TLLI fields, are marked as
de-registered, and can only be retrieved by a message containing an
IMSI or a P-TMSI.

The following VTY configuration commands are added to the gbproxy
node:
  - tlli-list keep-mode never : Don't keep the entries (default)
  - tlli-list keep-mode re-attach : Only keep them, when a Detach
    message with re-attach required has been received
  - tlli-list keep-mode identified : Only keep entries which are
    associated with an IMSI
  - tlli-list keep-mode always : Keep all entries

Note that at least one of max-length or max-age should be set when
this feature is used to limit the number of entries.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/gbproxy/gbproxy_test.ok b/openbsc/tests/gbproxy/gbproxy_test.ok
index 80a691e..49ab7e3 100644
--- a/openbsc/tests/gbproxy/gbproxy_test.ok
+++ b/openbsc/tests/gbproxy/gbproxy_test.ok
@@ -4344,25 +4344,27 @@
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
     Attach Request count            : 1
-    TLLI-Cache: 0
+    TLLI cache size                 : 1
+    TLLI-Cache: 1
+      TLLI 00000000, IMSI 12131415161718, AGE 0, DE-REGISTERED
 PROCESSING ATTACH REQUEST from 0x01020304:1111
 00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 15 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 e6 71 c7 
 
 CALLBACK, event 0, msg length 75, bvci 0x1002
 00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 15 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 e6 71 c7 
 
-NS UNITDATA MESSAGE to BSS, BVCI 0x1002, msg length 24 (gprs_ns_sendmsg)
-MESSAGE to BSS at 0x01020304:1111, msg length 28
-00 00 10 02 00 af e2 b7 00 00 50 20 16 82 02 58 0e 00 09 41 c4 01 08 15 01 b7 f8 36 
+NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 75 (gprs_ns_sendmsg)
+MESSAGE to SGSN at 0x05060708:32000, msg length 79
+00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 15 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 e6 71 c7 
 
-result (ATTACH REQUEST) = 0
+result (ATTACH REQUEST) = 79
 
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
     Attach Request count            : 2
     TLLI cache size                 : 1
     TLLI-Cache: 1
-      TLLI afe2b700 -> afe2b700, IMSI (none), AGE 0, STORED 1, IMSI acquisition in progress
+      TLLI afe2b700 -> afe2b700, IMSI 12131415161718, AGE 0
 PROCESSING ATTACH ACCEPT from 0x05060708:32000
 00 00 10 02 00 af e2 b7 00 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 11 08 02 01 49 04 21 63 54 40 50 60 19 cd d7 08 17 16 18 05 f4 ef e2 b7 00 3a 6d d4 
 
@@ -4380,17 +4382,13 @@
     Attach Request count            : 2
     TLLI cache size                 : 1
     TLLI-Cache: 1
-      TLLI afe2b700/efe2b700 -> afe2b700/efe2b700, IMSI 12131415161718, AGE 0, STORED 1, IMSI acquisition in progress
+      TLLI afe2b700/efe2b700 -> afe2b700/efe2b700, IMSI 12131415161718, AGE 0
 PROCESSING ATTACH COMPLETE from 0x01020304:1111
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 19 08 03 32 f1 bc 
 
 CALLBACK, event 0, msg length 31, bvci 0x1002
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 19 08 03 32 f1 bc 
 
-NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 75 (gprs_ns_sendmsg)
-MESSAGE to SGSN at 0x05060708:32000, msg length 79
-00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 15 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 e6 71 c7 
-
 NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 31 (gprs_ns_sendmsg)
 MESSAGE to SGSN at 0x05060708:32000, msg length 35
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 19 08 03 32 f1 bc 
@@ -4436,25 +4434,27 @@
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
     Attach Request count            : 2
-    TLLI-Cache: 0
+    TLLI cache size                 : 1
+    TLLI-Cache: 1
+      TLLI 00000000, IMSI 12131415161718, AGE 0, DE-REGISTERED
 PROCESSING ATTACH REQUEST from 0x01020304:1111
 00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 21 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 44 db cc 
 
 CALLBACK, event 0, msg length 75, bvci 0x1002
 00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 21 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 44 db cc 
 
-NS UNITDATA MESSAGE to BSS, BVCI 0x1002, msg length 24 (gprs_ns_sendmsg)
-MESSAGE to BSS at 0x01020304:1111, msg length 28
-00 00 10 02 00 af e2 b7 00 00 50 20 16 82 02 58 0e 00 09 41 c4 01 08 15 01 b7 f8 36 
+NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 75 (gprs_ns_sendmsg)
+MESSAGE to SGSN at 0x05060708:32000, msg length 79
+00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 21 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 44 db cc 
 
-result (ATTACH REQUEST) = 0
+result (ATTACH REQUEST) = 79
 
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
     Attach Request count            : 3
     TLLI cache size                 : 1
     TLLI-Cache: 1
-      TLLI afe2b700 -> afe2b700, IMSI (none), AGE 0, STORED 1, IMSI acquisition in progress
+      TLLI afe2b700 -> afe2b700, IMSI 12131415161718, AGE 0
 PROCESSING ATTACH ACCEPT from 0x05060708:32000
 00 00 10 02 00 af e2 b7 00 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 19 08 02 01 49 04 21 63 54 40 50 60 19 cd d7 08 17 16 18 05 f4 ef e2 b7 00 27 3c 84 
 
@@ -4472,17 +4472,13 @@
     Attach Request count            : 3
     TLLI cache size                 : 1
     TLLI-Cache: 1
-      TLLI afe2b700/efe2b700 -> afe2b700/efe2b700, IMSI 12131415161718, AGE 0, STORED 1, IMSI acquisition in progress
+      TLLI afe2b700/efe2b700 -> afe2b700/efe2b700, IMSI 12131415161718, AGE 0
 PROCESSING ATTACH COMPLETE from 0x01020304:1111
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 25 08 03 9b c6 47 
 
 CALLBACK, event 0, msg length 31, bvci 0x1002
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 25 08 03 9b c6 47 
 
-NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 75 (gprs_ns_sendmsg)
-MESSAGE to SGSN at 0x05060708:32000, msg length 79
-00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 21 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 44 db cc 
-
 NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 31 (gprs_ns_sendmsg)
 MESSAGE to SGSN at 0x05060708:32000, msg length 35
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 25 08 03 9b c6 47 
@@ -4528,25 +4524,27 @@
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
     Attach Request count            : 3
-    TLLI-Cache: 0
+    TLLI cache size                 : 1
+    TLLI-Cache: 1
+      TLLI 00000000, IMSI 12131415161718, AGE 0, DE-REGISTERED
 PROCESSING ATTACH REQUEST from 0x01020304:1111
 00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 2d 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 14 f4 a3 
 
 CALLBACK, event 0, msg length 75, bvci 0x1002
 00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 2d 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 14 f4 a3 
 
-NS UNITDATA MESSAGE to BSS, BVCI 0x1002, msg length 24 (gprs_ns_sendmsg)
-MESSAGE to BSS at 0x01020304:1111, msg length 28
-00 00 10 02 00 af e2 b7 00 00 50 20 16 82 02 58 0e 00 09 41 c4 01 08 15 01 b7 f8 36 
+NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 75 (gprs_ns_sendmsg)
+MESSAGE to SGSN at 0x05060708:32000, msg length 79
+00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 2d 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 14 f4 a3 
 
-result (ATTACH REQUEST) = 0
+result (ATTACH REQUEST) = 79
 
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
     Attach Request count            : 4
     TLLI cache size                 : 1
     TLLI-Cache: 1
-      TLLI afe2b700 -> afe2b700, IMSI (none), AGE 0, STORED 1, IMSI acquisition in progress
+      TLLI afe2b700 -> afe2b700, IMSI 12131415161718, AGE 0
 PROCESSING ATTACH ACCEPT from 0x05060708:32000
 00 00 10 02 00 af e2 b7 00 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 21 08 02 01 49 04 21 63 54 40 50 60 19 cd d7 08 17 16 18 05 f4 ef e2 b7 00 cf 80 6e 
 
@@ -4564,17 +4562,13 @@
     Attach Request count            : 4
     TLLI cache size                 : 1
     TLLI-Cache: 1
-      TLLI afe2b700/efe2b700 -> afe2b700/efe2b700, IMSI 12131415161718, AGE 0, STORED 1, IMSI acquisition in progress
+      TLLI afe2b700/efe2b700 -> afe2b700/efe2b700, IMSI 12131415161718, AGE 0
 PROCESSING ATTACH COMPLETE from 0x01020304:1111
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 31 08 03 fc 2b 11 
 
 CALLBACK, event 0, msg length 31, bvci 0x1002
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 31 08 03 fc 2b 11 
 
-NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 75 (gprs_ns_sendmsg)
-MESSAGE to SGSN at 0x05060708:32000, msg length 79
-00 00 10 02 01 af e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 34 01 c0 2d 08 01 02 f5 e0 21 08 02 05 f4 ef e2 b7 00 11 22 33 40 50 60 19 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 14 f4 a3 
-
 NS UNITDATA MESSAGE to SGSN, BVCI 0x1002, msg length 31 (gprs_ns_sendmsg)
 MESSAGE to SGSN at 0x05060708:32000, msg length 35
 00 00 10 02 01 ef e2 b7 00 00 00 04 08 88 11 22 33 40 50 60 12 34 00 80 0e 00 08 01 c0 31 08 03 fc 2b 11 
@@ -4712,8 +4706,9 @@
 Peers:
   NSEI 4096, BVCI 4098, not blocked, RAI 112-332-16464-96
     Attach Request count            : 5
-    TLLI cache size                 : 1
-    TLLI-Cache: 1
+    TLLI cache size                 : 2
+    TLLI-Cache: 2
+      TLLI 00000000, IMSI 12131415161718, AGE 0, DE-REGISTERED
       TLLI efe2b700 -> efe2b700, IMSI 12131415161718, AGE 0
 Gbproxy global:
 Test TLLI info expiry