add OER open type decoder

skeletons/oer_decoder.c

@@ -37,3 +37,58 @@ oer_decode(asn_codec_ctx_t *opt_codec_ctx,
 		ptr, size	/* Buffer and its size */
 		);
 }
+
+/*
+ * Open Type is encoded as a length (#8.6) followed by that number of bytes.
+ * Since we're just skipping, reading the length would be enough.
+ */
+ssize_t
+oer_open_type_skip(const void *bufptr, size_t size) {
+    size_t len = 0;
+    return oer_fetch_length(bufptr, size, &len);
+}
+
+/*
+ * Read the Open Type (X.696 (08/2015), #30).
+ * RETURN VALUES:
+ *       0:     More data expected than bufptr contains.
+ *      -1:     Fatal error deciphering length.
+ *      >0:     Number of bytes used from bufptr.
+ */
+ssize_t
+oer_open_type_get(asn_codec_ctx_t *opt_codec_ctx,
+                  struct asn_TYPE_descriptor_s *td,
+                  asn_oer_constraints_t *constraints, void **struct_ptr,
+                  const void *bufptr, size_t size) {
+
+    asn_dec_rval_t dr;
+    size_t container_len = 0;
+    ssize_t len_len;
+
+    /* Get the size of a length determinant */
+    len_len = oer_fetch_length(bufptr, size, &container_len);
+    if(len_len <= 0) {
+        return len_len; /* Error or more data expected */
+    }
+
+    /*
+     * len_len can't be bigger than size, but size without len_len
+     * should be bigger or equal to container length
+     */
+    if(size - len_len < container_len) {
+        /* More data is expected */
+        return 0;
+    }
+
+    dr = td->oer_decoder(opt_codec_ctx, td, constraints, struct_ptr,
+                         (const uint8_t *)bufptr + len_len, container_len);
+    if(dr.code == RC_OK) {
+        return len_len + container_len;
+    } else {
+        /* Even if RC_WMORE, we can't get more data into a closed container. */
+        ASN_STRUCT_FREE(*td, *struct_ptr);
+        *struct_ptr = 0;
+        return -1;
+    }
+}
+

skeletons/oer_decoder.h

@@ -44,7 +44,7 @@ typedef asn_dec_rval_t(oer_type_decoder_f)(
  *      -1:     Fatal error deciphering length.
  *      >0:     Number of bytes used from bufptr.
  */
-ssize_t oer_open_type_slurp(const void *bufptr, size_t size);
+ssize_t oer_open_type_skip(const void *bufptr, size_t size);
 
 /*
  * Read the Open Type (X.696 (08/2015), #30).