Fix 'Information Object Set XXX contains no objects' when parsing S1AP's ASN.1

The aforementioned error message displayed during processing the following ASN.1 excerpt.

S1AP-ELEMENTARY-PROCEDURES S1AP-ELEMENTARY-PROCEDURE ::= {
    S1AP-ELEMENTARY-PROCEDURES-CLASS-1 |
    S1AP-ELEMENTARY-PROCEDURES-CLASS-2,
    ...
}

S1AP-ELEMENTARY-PROCEDURES-CLASS-1 S1AP-ELEMENTARY-PROCEDURE ::= {
    handoverPreparation                |
...
    writeReplaceWarning,
    ...,
    uERadioCapabilityMatch             |
....
    uEContextResume
}

S1AP-ELEMENTARY-PROCEDURES-CLASS-2 S1AP-ELEMENTARY-PROCEDURE ::= {
    handoverNotification               |
...
    privateMessage,
    ...,
    downlinkUEAssociatedLPPaTransport  |
...
    mMECPRelocationIndication
}

Because S1AP-ELEMENTARY-PROCEDURES-CLASS-1 and S1AP-ELEMENTARY-PROCEDURES-CLASS-2
are resolved 'after' S1AP-ELEMENTARY-PROCEDURES, so the ioc tables of them are not
available during resolving S1AP-ELEMENTARY-PROCEDURES. So we can not drop the
latter's containedSubtype field at first pass of asn1f_resolve_constraints of fix
process.

We also add second pass of asn1f_resolve_constraints to have a chance to combine
ioc tables of S1AP-ELEMENTARY-PROCEDURES-CLASS-1 and
S1AP-ELEMENTARY-PROCEDURES-CLASS-2.

libasn1fix/asn1fix.c

@@ -262,6 +262,12 @@ asn1f_fix_module__phase_2(arg_t *arg) {
 		ret = asn1f_recurse_expr(arg, asn1f_fix_dereference_defaults);
 		RET2RVAL(ret, rvalue);
 
+		/*
+		 * Resolve references in constraints (the second pass).
+		 */
+		ret = asn1f_recurse_expr(arg, asn1f_resolve_constraints);
+		RET2RVAL(ret, rvalue);
+
 		/*
 		 * Check semantic validity of constraints.
 		 */

libasn1fix/asn1fix_constraint.c

@@ -21,6 +21,7 @@ asn1constraint_pullup(arg_t *arg) {
 	switch(expr->meta_type) {
 	case AMT_TYPE:
 	case AMT_TYPEREF:
+	case AMT_VALUESET:
 		break;
 	default:
 		return 0;	/* Nothing to do */
@@ -273,6 +274,7 @@ static int
 constraint_type_resolve(arg_t *arg, asn1p_constraint_t *ct) {
     asn1p_constraint_t *ct_expr;
     int ret;
+    asn1p_expr_t *rtype = (asn1p_expr_t *)0;
 
     DEBUG("(\"%s\")", asn1f_printable_value(ct->containedSubtype));
 
@@ -280,7 +282,6 @@ constraint_type_resolve(arg_t *arg, asn1p_constraint_t *ct) {
         ct_expr = ct->containedSubtype->value.constraint;
         DEBUG("Found %s in constraints", "ValueSet");
     } else if(get_reference_from(ct)) {
-        asn1p_expr_t *rtype;
         arg_t tmparg;
 
         rtype = asn1f_lookup_symbol(arg, arg->expr->rhs_pspecs,
@@ -299,6 +300,14 @@ constraint_type_resolve(arg_t *arg, asn1p_constraint_t *ct) {
         ret = asn1constraint_pullup(&tmparg);
         if(ret) return ret;
 
+        if(rtype->ioc_table) {
+            if(!arg->expr->ioc_table)
+                arg->expr->ioc_table = asn1p_ioc_table_new();
+            asn1p_ioc_table_append(arg->expr->ioc_table, rtype->ioc_table);
+            asn1p_value_free(ct->containedSubtype);
+            ct->containedSubtype = NULL;
+        }
+
         ct_expr = rtype->combined_constraints;
         if(!ct_expr) return 0;
     } else {
@@ -330,6 +339,14 @@ constraint_type_resolve(arg_t *arg, asn1p_constraint_t *ct) {
     }
 
     ct->type = ACT_CA_SET;
+
+    /* keep constrainedSubtype field for future usage,
+       if valueset has not been resolved yet. */
+    if(rtype &&
+        (rtype->meta_type == AMT_VALUESET) &&
+        (!rtype->ioc_table))
+        return 0;
+
     asn1p_value_free(ct->containedSubtype);
     ct->containedSubtype = NULL;
 

libasn1parser/asn1p_class.c

@@ -25,6 +25,16 @@ asn1p_ioc_table_add(asn1p_ioc_table_t *it, asn1p_ioc_row_t *row) {
     it->row[it->rows++] = row;
 }
 
+void
+asn1p_ioc_table_append(asn1p_ioc_table_t *it, asn1p_ioc_table_t *src) {
+
+    if(!src) return;
+
+    for(size_t i = 0; i < src->rows; i++) {
+        asn1p_ioc_table_add(it, asn1p_ioc_row_clone(src->row[i]));
+    }
+}
+
 void
 asn1p_ioc_table_free(asn1p_ioc_table_t *it) {
     if(it) {
@@ -93,6 +103,29 @@ asn1p_ioc_row_new(asn1p_expr_t *oclass) {
 	return row;
 }
 
+asn1p_ioc_row_t *
+asn1p_ioc_row_clone(asn1p_ioc_row_t *src) {
+	asn1p_ioc_row_t *row;
+
+	row = calloc(1, sizeof *row);
+	if(!row) return NULL;
+
+	row->column = calloc(src->columns, sizeof *src->column);
+	if(!row->column) {
+		free(row);
+		return NULL;
+	}
+	row->columns = src->columns;
+
+	for(size_t i = 0; i < src->columns; i++) {
+		row->column[i].field = src->column[i].field;
+		row->column[i].value = src->column[i].value ? asn1p_expr_clone(src->column[i].value, 0) : 0;
+		row->column[i].new_ref = 1;
+	}
+
+	return row;
+}
+
 void
 asn1p_ioc_row_delete(asn1p_ioc_row_t *row) {
 	if(row) {

libasn1parser/asn1p_class.h

@@ -16,6 +16,7 @@ typedef struct asn1p_ioc_row_s {
 } asn1p_ioc_row_t;
 
 asn1p_ioc_row_t *asn1p_ioc_row_new(struct asn1p_expr_s *oclass);
+asn1p_ioc_row_t *asn1p_ioc_row_clone(asn1p_ioc_row_t *src);
 size_t asn1p_ioc_row_max_identifier_length(asn1p_ioc_row_t *);
 void asn1p_ioc_row_delete(asn1p_ioc_row_t *);
 
@@ -27,6 +28,7 @@ typedef struct asn1p_ioc_table_s {
 
 asn1p_ioc_table_t *asn1p_ioc_table_new(void);
 void asn1p_ioc_table_add(asn1p_ioc_table_t *, asn1p_ioc_row_t *row);
+void asn1p_ioc_table_append(asn1p_ioc_table_t *it, asn1p_ioc_table_t *src);
 size_t asn1p_ioc_table_max_identifier_length(asn1p_ioc_table_t *);
 void asn1p_ioc_table_free(asn1p_ioc_table_t *);