Add ErrorIndication for S1AP decode error (#218)

lib/asn1c/s1ap-decoder.c

@@ -35,9 +35,9 @@ int s1ap_decode_pdu(s1ap_message_t *message, ogs_pkbuf_t *pkbuf)
     dec_ret = aper_decode(NULL, &asn_DEF_S1AP_S1AP_PDU, (void **)&message, 
             pkbuf->data, pkbuf->len, 0, 0);
 
-    if (dec_ret.code != RC_OK) 
-    {
-        ogs_error("Failed to decode S1AP-PDU[%d]", dec_ret.code);
+    if (dec_ret.code != RC_OK) {
+        ogs_warn("Failed to decode S1AP-PDU[code:%d,consumed:%d]",
+                dec_ret.code, dec_ret.consumed);
         return OGS_ERROR;
     }
 

src/mme/mme-sm.c

@@ -201,7 +201,11 @@ void mme_state_operational(ogs_fsm_t *s, mme_event_t *e)
             e->s1ap_message = &s1ap_message;
             ogs_fsm_dispatch(&enb->sm, e);
         } else {
-            ogs_error("Cannot process S1AP message");
+            ogs_warn("Cannot process S1AP message");
+            rv = s1ap_send_error_indication(
+                    enb, NULL, NULL, S1AP_Cause_PR_protocol, 
+                    S1AP_CauseProtocol_abstract_syntax_error_falsely_constructed_message);
+            ogs_assert(rv == OGS_OK);
         }
 
         s1ap_free_pdu(&s1ap_message);

tests/common/test-packet.c

@@ -318,6 +318,28 @@ int tests1ap_build_setup_req(
 
 #define TESTS1AP_MAX_MESSAGE 64
 
+int tests1ap_build_invalid_packet(ogs_pkbuf_t **pkbuf, int i)
+{
+    char *payload[TESTS1AP_MAX_MESSAGE] = {
+        "0011002100000300 3b40080062f22400 0001700040000700 00004062f224002c"
+        "00030a0100",
+        "",
+    };
+
+    uint16_t len[TESTS1AP_MAX_MESSAGE] = {
+        37,
+        0,
+    };
+
+    char hexbuf[MAX_SDU_LEN];
+    
+    *pkbuf = ogs_pkbuf_alloc(NULL, MAX_SDU_LEN);
+    ogs_pkbuf_put_data(*pkbuf, 
+        OGS_HEX(payload[i], strlen(payload[i]), hexbuf), len[i]);
+
+    return OGS_OK;
+}
+
 int tests1ap_build_initial_ue_msg(ogs_pkbuf_t **pkbuf, int i)
 {
     char *payload[TESTS1AP_MAX_MESSAGE] = {

tests/common/test-packet.h

@@ -48,6 +48,8 @@ ogs_pkbuf_t *testenb_gtpu_read(ogs_socknode_t *node);
 int testenb_gtpu_send(ogs_socknode_t *node, ogs_pkbuf_t *sendbuf);
 void testenb_gtpu_close(ogs_socknode_t *node);
 
+int tests1ap_build_invalid_packet(ogs_pkbuf_t **pkbuf, int i);
+
 int tests1ap_build_setup_req(
         ogs_pkbuf_t **pkbuf, S1AP_ENB_ID_PR present, uint32_t enb_id,
         int tac, uint16_t mcc, uint16_t mnc, uint16_t mnc_len);

tests/complex/s1setup-test.c

@@ -87,12 +87,36 @@ static void s1setup_test2(abts_case *tc, void *data)
     ogs_pkbuf_free(recvbuf);
 }
 
+static void s1setup_test3(abts_case *tc, void *data)
+{
+    int rv;
+    ogs_socknode_t *s1ap;
+    ogs_pkbuf_t *sendbuf;
+    ogs_pkbuf_t *recvbuf;
+
+    s1ap = testenb_s1ap_client("127.0.0.1");
+    ABTS_PTR_NOTNULL(tc, s1ap);
+
+    rv = tests1ap_build_invalid_packet(&sendbuf, 0);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    rv = testenb_s1ap_send(s1ap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    recvbuf = testenb_s1ap_read(s1ap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    ogs_pkbuf_free(recvbuf);
+
+    testenb_s1ap_close(s1ap);
+}
+
 abts_suite *test_s1setup(abts_suite *suite)
 {
     suite = ADD_SUITE(suite)
 
     abts_run_test(suite, s1setup_test1, NULL);
     abts_run_test(suite, s1setup_test2, NULL);
+    abts_run_test(suite, s1setup_test3, NULL);
 
     return suite;
 }