/*
   Unix SMB/CIFS implementation.
   raw dcerpc operations

   Copyright (C) Andrew Tridgell 2003-2005
   Copyright (C) Jelmer Vernooij 2004-2005

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "system/network.h"
#include <tevent.h>
#include "lib/tsocket/tsocket.h"
#include "lib/util/tevent_ntstatus.h"
#include "librpc/rpc/dcerpc.h"
#include "librpc/gen_ndr/ndr_dcerpc.h"
#include "rpc_common.h"

/* we need to be able to get/set the fragment length without doing a full
   decode */
void dcerpc_set_frag_length(DATA_BLOB *blob, uint16_t v)
{
	if (CVAL(blob->data,DCERPC_DREP_OFFSET) & DCERPC_DREP_LE) {
		SSVAL(blob->data, DCERPC_FRAG_LEN_OFFSET, v);
	} else {
		RSSVAL(blob->data, DCERPC_FRAG_LEN_OFFSET, v);
	}
}

uint16_t dcerpc_get_frag_length(const DATA_BLOB *blob)
{
	if (CVAL(blob->data,DCERPC_DREP_OFFSET) & DCERPC_DREP_LE) {
		return SVAL(blob->data, DCERPC_FRAG_LEN_OFFSET);
	} else {
		return RSVAL(blob->data, DCERPC_FRAG_LEN_OFFSET);
	}
}

void dcerpc_set_auth_length(DATA_BLOB *blob, uint16_t v)
{
	if (CVAL(blob->data,DCERPC_DREP_OFFSET) & DCERPC_DREP_LE) {
		SSVAL(blob->data, DCERPC_AUTH_LEN_OFFSET, v);
	} else {
		RSSVAL(blob->data, DCERPC_AUTH_LEN_OFFSET, v);
	}
}

uint8_t dcerpc_get_endian_flag(DATA_BLOB *blob)
{
	return blob->data[DCERPC_DREP_OFFSET];
}


/**
* @brief	Pull a dcerpc_auth structure, taking account of any auth
*		padding in the blob. For request/response packets we pass
*		the whole data blob, so auth_data_only must be set to false
*		as the blob contains data+pad+auth and no just pad+auth.
*
* @param pkt		- The ncacn_packet strcuture
* @param mem_ctx	- The mem_ctx used to allocate dcerpc_auth elements
* @param pkt_trailer	- The packet trailer data, usually the trailing
*			  auth_info blob, but in the request/response case
*			  this is the stub_and_verifier blob.
* @param auth		- A preallocated dcerpc_auth *empty* structure
* @param auth_length	- The length of the auth trail, sum of auth header
*			  lenght and pkt->auth_length
* @param auth_data_only	- Whether the pkt_trailer includes only the auth_blob
*			  (+ padding) or also other data.
*
* @return		- A NTSTATUS error code.
*/
NTSTATUS dcerpc_pull_auth_trailer(struct ncacn_packet *pkt,
				  TALLOC_CTX *mem_ctx,
				  DATA_BLOB *pkt_trailer,
				  struct dcerpc_auth *auth,
				  uint32_t *auth_length,
				  bool auth_data_only)
{
	struct ndr_pull *ndr;
	enum ndr_err_code ndr_err;
	uint32_t data_and_pad;

	data_and_pad = pkt_trailer->length
			- (DCERPC_AUTH_TRAILER_LENGTH + pkt->auth_length);

	/* paranoia check for pad size. This would be caught anyway by
	   the ndr_pull_advance() a few lines down, but it scared
	   Jeremy enough for him to call me, so we might as well check
	   it now, just to prevent someone posting a bogus YouTube
	   video in the future.
	*/
	if (data_and_pad > pkt_trailer->length) {
		return NT_STATUS_INFO_LENGTH_MISMATCH;
	}

	*auth_length = pkt_trailer->length - data_and_pad;

	ndr = ndr_pull_init_blob(pkt_trailer, mem_ctx);
	if (!ndr) {
		return NT_STATUS_NO_MEMORY;
	}

	if (!(pkt->drep[0] & DCERPC_DREP_LE)) {
		ndr->flags |= LIBNDR_FLAG_BIGENDIAN;
	}

	ndr_err = ndr_pull_advance(ndr, data_and_pad);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		talloc_free(ndr);
		return ndr_map_error2ntstatus(ndr_err);
	}

	ndr_err = ndr_pull_dcerpc_auth(ndr, NDR_SCALARS|NDR_BUFFERS, auth);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		talloc_free(ndr);
		return ndr_map_error2ntstatus(ndr_err);
	}

	if (auth_data_only && data_and_pad != auth->auth_pad_length) {
		DEBUG(1, (__location__ ": WARNING: pad length mismatch. "
			  "Calculated %u  got %u\n",
			  (unsigned)data_and_pad,
			  (unsigned)auth->auth_pad_length));
	}

	DEBUG(6,(__location__ ": auth_pad_length %u\n",
		 (unsigned)auth->auth_pad_length));

	talloc_steal(mem_ctx, auth->credentials.data);
	talloc_free(ndr);

	return NT_STATUS_OK;
}

struct dcerpc_read_ncacn_packet_state {
#if 0
	struct {
	} caller;
#endif
	DATA_BLOB buffer;
	struct ncacn_packet *pkt;
};

static int dcerpc_read_ncacn_packet_next_vector(struct tstream_context *stream,
						void *private_data,
						TALLOC_CTX *mem_ctx,
						struct iovec **_vector,
						size_t *_count);
static void dcerpc_read_ncacn_packet_done(struct tevent_req *subreq);

struct tevent_req *dcerpc_read_ncacn_packet_send(TALLOC_CTX *mem_ctx,
						 struct tevent_context *ev,
						 struct tstream_context *stream)
{
	struct tevent_req *req;
	struct dcerpc_read_ncacn_packet_state *state;
	struct tevent_req *subreq;

	req = tevent_req_create(mem_ctx, &state,
				struct dcerpc_read_ncacn_packet_state);
	if (req == NULL) {
		return NULL;
	}

	state->buffer = data_blob_const(NULL, 0);
	state->pkt = talloc(state, struct ncacn_packet);
	if (tevent_req_nomem(state->pkt, req)) {
		goto post;
	}

	subreq = tstream_readv_pdu_send(state, ev,
					stream,
					dcerpc_read_ncacn_packet_next_vector,
					state);
	if (tevent_req_nomem(subreq, req)) {
		goto post;
	}
	tevent_req_set_callback(subreq, dcerpc_read_ncacn_packet_done, req);

	return req;
 post:
	tevent_req_post(req, ev);
	return req;
}

static int dcerpc_read_ncacn_packet_next_vector(struct tstream_context *stream,
						void *private_data,
						TALLOC_CTX *mem_ctx,
						struct iovec **_vector,
						size_t *_count)
{
	struct dcerpc_read_ncacn_packet_state *state =
		talloc_get_type_abort(private_data,
		struct dcerpc_read_ncacn_packet_state);
	struct iovec *vector;
	off_t ofs = 0;

	if (state->buffer.length == 0) {
		/* first get enough to read the fragment length */
		ofs = 0;
		state->buffer.length = DCERPC_FRAG_LEN_OFFSET + 2;
		state->buffer.data = talloc_array(state, uint8_t,
						  state->buffer.length);
		if (!state->buffer.data) {
			return -1;
		}
	} else if (state->buffer.length == (DCERPC_FRAG_LEN_OFFSET + 2)) {
		/* now read the fragment length and allocate the full buffer */
		size_t frag_len = dcerpc_get_frag_length(&state->buffer);

		ofs = state->buffer.length;

		if (frag_len < ofs) {
			/*
			 * something is wrong, let the caller deal with it
			 */
			*_vector = NULL;
			*_count = 0;
			return 0;
		}

		state->buffer.data = talloc_realloc(state,
						    state->buffer.data,
						    uint8_t, frag_len);
		if (!state->buffer.data) {
			return -1;
		}
		state->buffer.length = frag_len;
	} else {
		/* if we reach this we have a full fragment */
		*_vector = NULL;
		*_count = 0;
		return 0;
	}

	/* now create the vector that we want to be filled */
	vector = talloc_array(mem_ctx, struct iovec, 1);
	if (!vector) {
		return -1;
	}

	vector[0].iov_base = (void *) (state->buffer.data + ofs);
	vector[0].iov_len = state->buffer.length - ofs;

	*_vector = vector;
	*_count = 1;
	return 0;
}

static void dcerpc_read_ncacn_packet_done(struct tevent_req *subreq)
{
	struct tevent_req *req = tevent_req_callback_data(subreq,
				 struct tevent_req);
	struct dcerpc_read_ncacn_packet_state *state = tevent_req_data(req,
					struct dcerpc_read_ncacn_packet_state);
	int ret;
	int sys_errno;
	struct ndr_pull *ndr;
	enum ndr_err_code ndr_err;
	NTSTATUS status;

	ret = tstream_readv_pdu_recv(subreq, &sys_errno);
	TALLOC_FREE(subreq);
	if (ret == -1) {
		status = map_nt_error_from_unix_common(sys_errno);
		tevent_req_nterror(req, status);
		return;
	}

	ndr = ndr_pull_init_blob(&state->buffer, state->pkt);
	if (tevent_req_nomem(ndr, req)) {
		return;
	}

	if (!(CVAL(ndr->data, DCERPC_DREP_OFFSET) & DCERPC_DREP_LE)) {
		ndr->flags |= LIBNDR_FLAG_BIGENDIAN;
	}

	if (CVAL(ndr->data, DCERPC_PFC_OFFSET) & DCERPC_PFC_FLAG_OBJECT_UUID) {
		ndr->flags |= LIBNDR_FLAG_OBJECT_PRESENT;
	}

	ndr_err = ndr_pull_ncacn_packet(ndr, NDR_SCALARS|NDR_BUFFERS, state->pkt);
	TALLOC_FREE(ndr);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		status = ndr_map_error2ntstatus(ndr_err);
		tevent_req_nterror(req, status);
		return;
	}

	if (state->pkt->frag_length != state->buffer.length) {
		tevent_req_nterror(req, NT_STATUS_RPC_PROTOCOL_ERROR);
		return;
	}

	tevent_req_done(req);
}

NTSTATUS dcerpc_read_ncacn_packet_recv(struct tevent_req *req,
				       TALLOC_CTX *mem_ctx,
				       struct ncacn_packet **pkt,
				       DATA_BLOB *buffer)
{
	struct dcerpc_read_ncacn_packet_state *state = tevent_req_data(req,
					struct dcerpc_read_ncacn_packet_state);
	NTSTATUS status;

	if (tevent_req_is_nterror(req, &status)) {
		tevent_req_received(req);
		return status;
	}

	*pkt = talloc_move(mem_ctx, &state->pkt);
	if (buffer) {
		buffer->data = talloc_move(mem_ctx, &state->buffer.data);
		buffer->length = state->buffer.length;
	}

	tevent_req_received(req);
	return NT_STATUS_OK;
}