der_encode_to_buffer()

1 files changed, 44 insertions, 0 deletions

diff --git a/skeletons/der_encoder.c b/skeletons/der_encoder.c
index 3523cb12..b2763c7c 100644
--- a/skeletons/der_encoder.c
+++ b/skeletons/der_encoder.c
@@ -29,6 +29,50 @@ der_encode(asn_TYPE_descriptor_t *type_descriptor, void *struct_ptr,
 }
 
 /*
+ * Argument type and callback necessary for der_encode_to_buffer().
+ */
+typedef struct enc_to_buf_arg {
+	void *buffer;
+	size_t left;
+} enc_to_buf_arg;
+static int encode_to_buffer_cb(const void *buffer, size_t size, void *key) {
+	enc_to_buf_arg *arg = key;
+
+	if(arg->left < size)
+		return -1;	/* Data exceeds the available buffer size */
+
+	memcpy(arg->buffer, buffer, size);
+	arg->buffer = ((char *)arg->buffer) + size;
+	arg->left -= size;
+
+	return 0;
+}
+
+/*
+ * A variant of the der_encode() which encodes the data into the provided buffer
+ */
+asn_enc_rval_t
+der_encode_to_buffer(asn_TYPE_descriptor_t *type_descriptor, void *struct_ptr,
+	void *buffer, size_t *buffer_size) {
+	enc_to_buf_arg arg;
+	asn_enc_rval_t ec;
+
+	arg.buffer = buffer;
+	arg.left = *buffer_size;
+
+	ec = type_descriptor->der_encoder(type_descriptor,
+		struct_ptr,	/* Pointer to the destination structure */
+		0, 0, encode_to_buffer_cb, &arg);
+	if(ec.encoded != -1) {
+		assert(ec.encoded == (*buffer_size - arg.left));
+		/* Return the encoded contents size */
+		*buffer_size = ec.encoded;
+	}
+	return ec;
+}
+
+
+/*
  * Write out leading TL[v] sequence according to the type definition.
  */
 ssize_t