gb: Fix gprs_ns_rx_reset to not create NS-VC duplicates

Under special circumstances (see below) receiving a NS-RESET leads to
duplicated NS-VC entries.

This happens when the source port of a NS-VC changes to a new one
that has already been used by another NS-VC.

This patch changes gprs_ns_rx_reset() to check for this case and to
use the existing NS-VC object. The NS-VC object that was associated
with the source address before is detached from this source but kept
in the NS-VC list so that it can be reattached when a correspondent
NS-RESET is received later on. Meanwhile it will have a cleared link
layer address which will not match a real link info.

A new counter NS_CTR_REPLACED is incremented each time when the NS-VC
object is replacing another one. A new signal S_NS_REPLACED is added
which gets dispatched in this case, too.

Another new counter NS_CTR_NSEI_CHG is incremented each time when the
NSEI of a NS-VC object (with fixed NSVCI) changes.

Ticket: OW#874
Sponsored-by: On-Waves ehf

2 files changed, 35 insertions, 3 deletions

diff --git a/tests/gb/gprs_ns_test.c b/tests/gb/gprs_ns_test.c
index 1474fd4d..d7b769df 100644
--- a/tests/gb/gprs_ns_test.c
+++ b/tests/gb/gprs_ns_test.c
@@ -21,6 +21,7 @@
 #include <osmocom/core/logging.h>
 #include <osmocom/core/talloc.h>
 #include <osmocom/core/signal.h>
+#include <osmocom/core/rate_ctr.h>
 #include <osmocom/gprs/gprs_msgb.h>
 #include <osmocom/gprs/gprs_ns.h>
 #include <osmocom/gprs/gprs_bssgp.h>
@@ -113,7 +114,7 @@ ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
 	if (!real_sendto)
 		real_sendto = dlsym(RTLD_NEXT, "sendto");
 
-	if (sockfd != 0xdead && ((struct sockaddr_in *)dest_addr)->sin_addr.s_addr != htonl(0x01020304))
+	if (((struct sockaddr_in *)dest_addr)->sin_addr.s_addr != htonl(0x01020304))
 		return real_sendto(sockfd, buf, len, flags, dest_addr, addrlen);
 
 	printf("RESPONSE, msg length %d\n%s\n\n", len, osmo_hexdump(buf, len));
@@ -121,6 +122,21 @@ ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
 	return len;
 }
 
+static void dump_rate_ctr_group(FILE *stream, const char *prefix,
+			    struct rate_ctr_group *ctrg)
+{
+	unsigned int i;
+
+	for (i = 0; i < ctrg->desc->num_ctr; i++) {
+		struct rate_ctr *ctr = &ctrg->ctr[i];
+		if (ctr->current && !strchr(ctrg->desc->ctr_desc[i].name, '.'))
+			fprintf(stream, " %s%s: %llu%s",
+				prefix, ctrg->desc->ctr_desc[i].description,
+				(long long)ctr->current,
+				"\n");
+	};
+}
+
 /* Signal handler for signals from NS layer */
 static int test_signal(unsigned int subsys, unsigned int signal,
 		  void *handler_data, void *signal_data)
@@ -155,6 +171,15 @@ static int test_signal(unsigned int subsys, unsigned int signal,
 		       gprs_ns_ll_str(nssd->nsvc));
 		break;
 
+	case S_NS_REPLACED:
+		printf("==> got signal NS_REPLACED: 0x%04x/%s",
+		       nssd->nsvc->nsvci,
+		       gprs_ns_ll_str(nssd->nsvc));
+		printf(" -> 0x%04x/%s\n",
+		       nssd->old_nsvc->nsvci,
+		       gprs_ns_ll_str(nssd->old_nsvc));
+		break;
+
 	default:
 		printf("==> got signal %d, NS-VC 0x%04x/%s\n", signal,
 		       nssd->nsvc->nsvci,
@@ -203,6 +228,7 @@ static void gprs_dump_nsi(struct gprs_ns_inst *nsi)
 		       nsvc->nsvci, nsvc->nsei,
 		       ntohl(peer->sin_addr.s_addr), ntohs(peer->sin_port)
 		      );
+		dump_rate_ctr_group(stdout, "        ", nsvc->ctrg);
 	}
 	printf("\n");
 }
diff --git a/tests/gb/gprs_ns_test.ok b/tests/gb/gprs_ns_test.ok
index 01b1bc91..7be84ef7 100644
--- a/tests/gb/gprs_ns_test.ok
+++ b/tests/gb/gprs_ns_test.ok
@@ -91,12 +91,14 @@ result (RESET) = 9
 Current NS-VCIs:
     VCI 0x3344, NSEI 0x1122, peer 0x01020304:3333
     VCI 0x1122, NSEI 0x3344, peer 0x01020304:4444
+         NS-VC changed NSEI        : 1
 
 --- Peer port 3333, RESET, VCI is changed back ---
 
 PROCESSING RESET from 0x01020304:3333
 02 00 81 01 01 82 11 22 04 82 11 22 
 
+==> got signal NS_REPLACED: 0x1122/1.2.3.4:4444 -> 0x3344/1.2.3.4:3333
 ==> got signal NS_RESET, NS-VC 0x1122/1.2.3.4:3333
 RESPONSE, msg length 9
 03 01 82 11 22 04 82 11 22 
@@ -107,8 +109,10 @@ RESPONSE, msg length 1
 result (RESET) = 9
 
 Current NS-VCIs:
+    VCI 0x3344, NSEI 0x1122, peer 0x00000000:0
     VCI 0x1122, NSEI 0x1122, peer 0x01020304:3333
-    VCI 0x1122, NSEI 0x3344, peer 0x01020304:4444
+         NS-VC replaced other count: 1
+         NS-VC changed NSEI        : 2
 
 --- Peer port 4444, RESET, NSEI is changed back ---
 
@@ -125,8 +129,10 @@ RESPONSE, msg length 1
 result (RESET) = 9
 
 Current NS-VCIs:
-    VCI 0x1122, NSEI 0x1122, peer 0x01020304:3333
+    VCI 0x3344, NSEI 0x1122, peer 0x00000000:0
     VCI 0x1122, NSEI 0x1122, peer 0x01020304:4444
+         NS-VC replaced other count: 1
+         NS-VC changed NSEI        : 2
 
 ===== NS protocol test END