paging: pass struct osmo_mobile_identity, not encoded IE bytes

In get_paging_mi(), before this, an encoded buffer of Mobile Identity bytes is
returned. Code paths following this repeatedly decode the Mobile Identity
bytes, e.g. for logging. Also, in get_paging_mi(), since the TMSI is read in
from a different encoding than a typical Mobile Identity IE, the TMSI was
manually encoded into a typical Mobile Identity IE. This is essentially a code
dup of osmo_mobile_identity_encode(). Stop this madness.

Instead, in get_paging_mi(), return a decoded struct osmo_mobile_identity. Code
paths after this use the struct osmo_mobile_identity directly without repeated
decoding.

At the point of finally needing an encoded Mobile Identity IE (in
Encoding::write_paging_request()), do a proper osmo_mobile_identity_encode().

Since this may return errors, add an rc check for the caller of
write_paging_request(), gprs_rlcmac_paging_request().

A side effect is stricter validation of the Mobile Identity passing through the
Paging code path. Before, invalid MI might have passed through unnoticed.

Change-Id: Iad845acb0096b75dc453105c9c16b2252879b4ca

1 files changed, 9 insertions, 3 deletions

diff --git a/src/pdch.cpp b/src/pdch.cpp
index af847241..fbbeddc5 100644
--- a/src/pdch.cpp
+++ b/src/pdch.cpp
@@ -266,15 +266,21 @@ free_ret:
 	return NULL;
 }
 
-bool gprs_rlcmac_pdch::add_paging(uint8_t chan_needed, const uint8_t *mi, uint8_t mi_len)
+bool gprs_rlcmac_pdch::add_paging(uint8_t chan_needed, const struct osmo_mobile_identity *mi)
 {
+	int rc;
 	struct gprs_rlcmac_paging *pag = talloc_zero(tall_pcu_ctx, struct gprs_rlcmac_paging);
 	if (!pag)
 		return false;
 
 	pag->chan_needed = chan_needed;
-	pag->identity_lv[0] = mi_len;
-	memcpy(&pag->identity_lv[1], mi, mi_len);
+	rc = osmo_mobile_identity_encode_buf(pag->identity_lv + 1, sizeof(pag->identity_lv) - 1, mi, true);
+	if (rc <= 0) {
+		LOGP(DRLCMAC, LOGL_ERROR, "Cannot encode Mobile Identity (rc=%d)\n", rc);
+		talloc_free(pag);
+		return false;
+	}
+	pag->identity_lv[0] = rc;
 
 	llist_add(&pag->list, &paging_list);