gistfile1.c

/*
 * This function ensures that there is required amount of data in the
 * ndr stream. When there isn't, it tries to read as much data as
 * possible in order to reduce the number of recv() calls. It grows
 * the stream if necessary. It relies on pdu_size so be careful.
 */
static int
nds_fetch(int sock, ndr_stream_t *nds, size_t need)
{
	ssize_t rc;
	size_t size = nds->pdu_size;
	size_t avail = size - nds->pdu_scan_offset;

	if (need > avail) {
		NDS_GROW_PDU(nds, size + need, NULL);

		rc = recv_min(sock,
			(uint8_t *)nds->pdu_base_offset + size,
			nds->pdu_max_size - size,
			need - avail);

		if (rc == -1)
			return (errno);

		nds->pdu_size = size + rc;
	}

	return (0);
}

/*
 * Read the incoming fragments and defragment the message on the go.
 */
static int
ndr_session_read_fragments(ndr_session_t *session)
{
	ndr_xa_t *mxa = &session->mxa;
	ndr_stream_t *nds = &mxa->recv_nds;
	ndr_common_header_t frag_hdr;
	int rc;
	int nfrags = 0;
	int frag_size;

	/*
	 * TODO: in some cases we should generate a proper error reply in
	 * RPC form, not just -1 and broken pipe on the other side.
	 */

	do {
		rc = nds_fetch(session->sock, nds,
			sizeof (ndr_common_header_t));
		if (rc != 0)
			return (rc);

		ndr_decode_frag_hdr(nds, &frag_hdr);
		ndr_show_hdr(&frag_hdr);

		if ((frag_hdr.rpc_vers != 5) || (frag_hdr.rpc_vers_minor != 0))
			return (-1);

		frag_size = frag_hdr.frag_length;

		rc = nds_fetch(session->sock, nds, frag_size);
		if (rc != 0)
			return (rc);

		if (NDR_IS_FIRST_FRAG(frag_hdr.pfc_flags)) {
			if (nfrags > 0)
				return (-1);
			nds->pdu_scan_offset = frag_size;
		} else {
			ndr_remove_frag_hdr(nds);
			nds->pdu_scan_offset += frag_size - NDR_RSP_HDR_SIZE;
		}

		nfrags++;
	} while (!NDR_IS_LAST_FRAG(frag_hdr.pfc_flags));

	nds->pdu_scan_offset = 0;
	return (0);
}