gbproxy: Refuse to configure conflicting NSEIs

Currently it is possible to set the secondary SGSN NSEI to the same
value like the (primary) SGSN NSEI. This leads to undefined behaviour
and is hard to recognize.

This patch adds checks to either NSEI configuration command to refuse
conflicting values.

Ticket: OW#1306
Sponsored-by: On-Waves ehf

1 files changed, 17 insertions, 3 deletions

diff --git a/openbsc/src/gprs/gb_proxy_vty.c b/openbsc/src/gprs/gb_proxy_vty.c
index eb7eb600a..8a7523c4e 100644
--- a/openbsc/src/gprs/gb_proxy_vty.c
+++ b/openbsc/src/gprs/gb_proxy_vty.c
@@ -150,9 +150,15 @@ DEFUN(cfg_nsip_sgsn_nsei,
       "NSEI to be used in the connection with the SGSN\n"
       "The NSEI\n")
 {
-	unsigned int port = atoi(argv[0]);
+	unsigned int nsei = atoi(argv[0]);
 
-	g_cfg->nsip_sgsn_nsei = port;
+	if (g_cfg->route_to_sgsn2 && g_cfg->nsip_sgsn2_nsei == nsei) {
+		vty_out(vty, "SGSN NSEI %d conflicts with secondary SGSN NSEI%s",
+			nsei, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_cfg->nsip_sgsn_nsei = nsei;
 	return CMD_SUCCESS;
 }
 
@@ -359,8 +365,16 @@ DEFUN(cfg_gbproxy_secondary_sgsn,
       "NSEI to be used in the connection with the SGSN\n"
       "The NSEI\n")
 {
+	unsigned int nsei = atoi(argv[0]);
+
+	if (g_cfg->nsip_sgsn_nsei == nsei) {
+		vty_out(vty, "Secondary SGSN NSEI %d conflicts with primary SGSN NSEI%s",
+			nsei, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
 	g_cfg->route_to_sgsn2 = 1;
-	g_cfg->nsip_sgsn2_nsei = atoi(argv[0]);
+	g_cfg->nsip_sgsn2_nsei = nsei;
 
 	g_cfg->patch_ptmsi = 1;