laforge has uploaded this change for review. (
https://gerrit.osmocom.org/c/libosmo-sccp/+/18818 )
Change subject: M3UA: Accept DATA without routing context IE if only a single
AS in ASP
......................................................................
M3UA: Accept DATA without routing context IE if only a single AS in ASP
There are some M3UA implementations out there who use a routing context
during the ASPAC procedure, but who then don't use it in subsequent DATA
transmission.
This behavior seems to be at the edge of what's possible within the
spec; if you don't configure a routing context, The RCTX IE it is not
required to be sent. And if you have multiple routing contexts/AS within
one ASP, it *must* be sent. But the situation where a routing context
has been configured (but not multiple) is not explicitly covered.
Change-Id: I59f47a999f40411aadc88b8f362d8d2b89a66332
Closes: OS#4594
---
M src/m3ua.c
1 file changed, 49 insertions(+), 20 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/libosmo-sccp refs/changes/18/18818/1
diff --git a/src/m3ua.c b/src/m3ua.c
index 5ab3e79..08a89b5 100644
--- a/src/m3ua.c
+++ b/src/m3ua.c
@@ -532,9 +532,26 @@
return data_hdr;
}
+/* if given ASP only has one AS, return that AS */
+static struct osmo_ss7_as *find_single_as_for_asp(struct osmo_ss7_asp *asp)
+{
+ struct osmo_ss7_as *as, *as_found = NULL;
+
+ llist_for_each_entry(as, &asp->inst->as_list, list) {
+ if (!osmo_ss7_as_has_asp(as, asp))
+ continue;
+ /* check if we already had found another AS within this ASP ->
not unique */
+ if (as_found)
+ return NULL;
+ as_found = as;
+ }
+
+ return as_found;
+}
+
static int m3ua_rx_xfer(struct osmo_ss7_asp *asp, struct xua_msg *xua)
{
- uint32_t rctx = xua_msg_get_u32(xua, M3UA_IEI_ROUTE_CTX);
+ struct xua_msg_part *rctx_ie = xua_msg_find_tag(xua,
M3UA_IEI_ROUTE_CTX);
struct m3ua_data_hdr *dh;
struct osmo_ss7_as *as;
@@ -548,23 +565,33 @@
return M3UA_ERR_UNSUPP_MSG_TYPE;
}
- /* Use routing context IE to look up the AS for which the
- * message was received. */
- as = osmo_ss7_as_find_by_rctx(asp->inst, rctx);
- if (!as) {
- LOGPASP(asp, DLM3UA, LOGL_ERROR,
- "%s(): invalid routing context: %u\n",
- __func__, rctx);
- return M3UA_ERR_INVAL_ROUT_CTX;
- }
+ if (rctx_ie) {
+ uint32_t rctx = xua_msg_part_get_u32(rctx_ie);
+ /* Use routing context IE to look up the AS for which the
+ * message was received. */
+ as = osmo_ss7_as_find_by_rctx(asp->inst, rctx);
+ if (!as) {
+ LOGPASP(asp, DLM3UA, LOGL_ERROR, "%s(): invalid routing
context: %u\n",
+ __func__, rctx);
+ return M3UA_ERR_INVAL_ROUT_CTX;
+ }
- /* Verify that this ASP is part of the AS. */
- if (!osmo_ss7_as_has_asp(as, asp)) {
- LOGPASP(asp, DLM3UA, LOGL_ERROR,
- "%s(): This Application Server Process is not part of
the AS %s resolved by"
- " routing context %u\n",
- __func__, (as)->cfg.name, rctx);
- return M3UA_ERR_NO_CONFGD_AS_FOR_ASP;
+ /* Verify that this ASP is part of the AS. */
+ if (!osmo_ss7_as_has_asp(as, asp)) {
+ LOGPASP(asp, DLM3UA, LOGL_ERROR,
+ "%s(): This Application Server Process is not
part of the AS %s "
+ "resolved by routing context %u\n", __func__,
(as)->cfg.name, rctx);
+ return M3UA_ERR_NO_CONFGD_AS_FOR_ASP;
+ }
+ } else {
+ /* no explicit routing context; this only works if there is
only one AS in the ASP */
+ as = find_single_as_for_asp(asp);
+ if (!as) {
+ LOGPASP(asp, DLM3UA, LOGL_ERROR,
+ "%s(): ASP sent M3UA without Routing Context IE
but unable to uniquely "
+ "identify the AS for this message\n", __func__);
+ return M3UA_ERR_INVAL_ROUT_CTX;
+ }
}
/* FIXME: check for AS state == ACTIVE */
@@ -579,9 +606,11 @@
__func__, xua->mtp.opc, osmo_ss7_pointcode_print(asp->inst,
xua->mtp.opc),
xua->mtp.dpc, osmo_ss7_pointcode_print2(asp->inst,
xua->mtp.dpc));
- /* remove ROUTE_CTX as in the routing case we want to add a new
- * routing context on the outbound side */
- xua_msg_free_tag(xua, M3UA_IEI_ROUTE_CTX);
+ if (rctx_ie) {
+ /* remove ROUTE_CTX as in the routing case we want to add a new
+ * routing context on the outbound side */
+ xua_msg_free_tag(xua, M3UA_IEI_ROUTE_CTX);
+ }
return m3ua_hmdc_rx_from_l2(asp->inst, xua);
/* xua will be freed by caller m3ua_rx_msg() */
--
To view, visit https://gerrit.osmocom.org/c/libosmo-sccp/+/18818
To unsubscribe, or for help writing mail filters, visit
https://gerrit.osmocom.org/settings
Gerrit-Project: libosmo-sccp
Gerrit-Branch: master
Gerrit-Change-Id: I59f47a999f40411aadc88b8f362d8d2b89a66332
Gerrit-Change-Number: 18818
Gerrit-PatchSet: 1
Gerrit-Owner: laforge <lafo...@osmocom.org>
Gerrit-MessageType: newchange
