From 0ab74c122c8965a916fc395c0f72d4599aeb3f9f Mon Sep 17 00:00:00 2001
From: Holger Hans Peter Freyther <zecke@selfish.org>
Date: Fri, 21 Oct 2011 14:11:04 +0200
Subject: [PATCH] gsm: Verify the MNCC_VERSION of the BSC/MS and close the
 socket on mismatch

The BSC/MS will send a Hello packet that includes the version number,
make LCR verify this version number and close the socket in case it
does not match a supported version.
---
 gsm.cpp | 12 ++++++++++++
 mncc.h  |  7 +++++++
 2 files changed, 19 insertions(+)

diff --git a/gsm.cpp b/gsm.cpp
index 31a7967..ee46ff6 100644
--- a/gsm.cpp
+++ b/gsm.cpp
@@ -1109,6 +1109,7 @@ static int mncc_fd_read(struct lcr_fd *lfd, void *inst, int idx)
 	int rc;
 	static char buf[sizeof(struct gsm_mncc)+1024];
 	struct gsm_mncc *mncc_prim = (struct gsm_mncc *) buf;
+	struct gsm_mncc_hello *hello = (struct gsm_mncc_hello *) buf;
 
 	memset(buf, 0, sizeof(buf));
 	rc = recv(lfd->fd, buf, sizeof(buf), 0);
@@ -1117,6 +1118,17 @@ static int mncc_fd_read(struct lcr_fd *lfd, void *inst, int idx)
 	if (rc < 0)
 		return rc;
 
+	/* TODO: size check? */
+	switch (mncc_prim->msg_type) {
+	case MNCC_SOCKET_HELLO:
+		if (hello->version != MNCC_SOCK_VERSION) {
+			PERROR("MNCC version different. BSC version is %u\n", hello->version);
+			mncc_fd_close(lcr_gsm, lfd);
+			return 0;
+		}
+		break;
+	}
+
 	/* Hand the MNCC message into LCR */
 	switch (lcr_gsm->type) {
 #ifdef WITH_GSM_BS
diff --git a/mncc.h b/mncc.h
index 25af62a..16509bd 100644
--- a/mncc.h
+++ b/mncc.h
@@ -62,6 +62,8 @@
 #define GSM_TCH_FRAME_AMR	0x0303
 #define GSM_BAD_FRAME		0x03ff
 
+#define MNCC_SOCKET_HELLO	0x0400
+
 #define GSM_MAX_FACILITY	128
 #define GSM_MAX_SSVERSION	128
 #define GSM_MAX_USERUSER	128
@@ -201,3 +203,8 @@ struct gsm_mncc_rtp {
 };
 
 
+#define MNCC_SOCK_VERSION	1
+struct gsm_mncc_hello {
+	u_int32_t	msg_type;
+	u_int32_t	version;
+};
-- 
2.13.6