From a914daf174e9d1a78bdccb1d5bd8b69ec8ff2280 Mon Sep 17 00:00:00 2001
From: Holger Hans Peter Freyther <zecke@selfish.org>
Date: Thu, 21 Oct 2010 12:12:57 +0200
Subject: [PATCH] nat: Add hook for rewriting a setup message

Create a new function, hand the data to this function, take back
a possible modified msgb and invalidate parsed at this point.
---
 openbsc/include/openbsc/bsc_nat.h |  2 ++
 openbsc/src/nat/bsc_nat.c         | 12 +++++++++++-
 openbsc/src/nat/bsc_nat_utils.c   |  7 +++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index 083746f68..049421716 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -343,4 +343,6 @@ struct gsm48_hdr *bsc_unpack_dtap(struct bsc_nat_parsed *parsed, struct msgb *ms
 int bsc_ussd_init(struct bsc_nat *nat);
 int bsc_check_ussd(struct sccp_connections *con, struct bsc_nat_parsed *parsed, struct msgb *msg);
 
+struct msgb *bsc_nat_rewrite_setup(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *);
+
 #endif
diff --git a/openbsc/src/nat/bsc_nat.c b/openbsc/src/nat/bsc_nat.c
index daabf0976..dcacfb9ab 100644
--- a/openbsc/src/nat/bsc_nat.c
+++ b/openbsc/src/nat/bsc_nat.c
@@ -858,6 +858,15 @@ static int forward_sccp_to_msc(struct bsc_connection *bsc, struct msgb *msg)
 					/* hand data to a side channel */
 					if (bsc_check_ussd(con, parsed, msg) == 1) 
 						con->con_local = 2;
+
+					/*
+					 * Optionally rewrite setup message. This can
+					 * replace the msg and the parsed structure becomes
+					 * invalid.
+					 */
+					msg = bsc_nat_rewrite_setup(bsc->nat, msg, parsed);
+					talloc_free(parsed);
+					parsed = NULL;
 				}
 
 				con_bsc = con->bsc;
@@ -913,7 +922,8 @@ static int forward_sccp_to_msc(struct bsc_connection *bsc, struct msgb *msg)
 
 	/* send the non-filtered but maybe modified msg */
 	queue_for_msc(con_msc, msg);
-	talloc_free(parsed);
+	if (parsed)
+		talloc_free(parsed);
 	return 0;
 
 exit:
diff --git a/openbsc/src/nat/bsc_nat_utils.c b/openbsc/src/nat/bsc_nat_utils.c
index 0cef01b24..a3fd97aaf 100644
--- a/openbsc/src/nat/bsc_nat_utils.c
+++ b/openbsc/src/nat/bsc_nat_utils.c
@@ -721,3 +721,10 @@ int bsc_write_cb(struct bsc_fd *bfd, struct msgb *msg)
 	return rc;
 }
 
+/**
+ * Rewrite non global numbers... according to rules based on the IMSI
+ */
+struct msgb *bsc_nat_rewrite_setup(struct bsc_nat *nat, struct msgb *msg, struct bsc_nat_parsed *pa)
+{
+	return msg;
+}