/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 The FreeBSD Foundation
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/types.h>
#include <sys/uio.h>
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <iscsi_proto.h>
#include "libiscsiutil.h"

int
pdu_ahs_length(const struct pdu *pdu)
{

        return (pdu->pdu_bhs->bhs_total_ahs_len * 4);
}

int
pdu_data_segment_length(const struct pdu *pdu)
{
        uint32_t len = 0;

        len += pdu->pdu_bhs->bhs_data_segment_len[0];
        len <<= 8;
        len += pdu->pdu_bhs->bhs_data_segment_len[1];
        len <<= 8;
        len += pdu->pdu_bhs->bhs_data_segment_len[2];

        return (len);
}

void
pdu_set_data_segment_length(struct pdu *pdu, uint32_t len)
{

        pdu->pdu_bhs->bhs_data_segment_len[2] = len;
        pdu->pdu_bhs->bhs_data_segment_len[1] = len >> 8;
        pdu->pdu_bhs->bhs_data_segment_len[0] = len >> 16;
}

struct pdu *
pdu_new(struct connection *conn)
{
        struct pdu *pdu;

        pdu = calloc(1, sizeof(*pdu));
        if (pdu == NULL)
                log_err(1, "calloc");

        pdu->pdu_bhs = calloc(1, sizeof(*pdu->pdu_bhs));
        if (pdu->pdu_bhs == NULL)
                log_err(1, "calloc");

        pdu->pdu_connection = conn;

        return (pdu);
}

struct pdu *
pdu_new_response(struct pdu *request)
{

        return (pdu_new(request->pdu_connection));
}

static size_t
pdu_padding(const struct pdu *pdu)
{

        if ((pdu->pdu_data_len % 4) != 0)
                return (4 - (pdu->pdu_data_len % 4));

        return (0);
}

static void
pdu_read(const struct connection *conn, char *data, size_t len)
{
        ssize_t ret;

        while (len > 0) {
                ret = read(conn->conn_socket, data, len);
                if (ret < 0) {
                        if (conn->conn_ops->timed_out()) {
                                conn->conn_ops->fail(conn,
                                    "Login Phase timeout");
                                log_errx(1, "exiting due to timeout");
                        }
                        conn->conn_ops->fail(conn, strerror(errno));
                        log_err(1, "read");
                } else if (ret == 0) {
                        conn->conn_ops->fail(conn, "connection lost");
                        log_errx(1, "read: connection lost");
                }
                len -= ret;
                data += ret;
        }
}

void
pdu_receive(struct pdu *pdu)
{
        struct connection *conn;
        size_t len, padding;
        char dummy[4];

        conn = pdu->pdu_connection;
        if (conn->conn_use_proxy)
                return (conn->conn_ops->pdu_receive_proxy(pdu));

        pdu_read(conn, (char *)pdu->pdu_bhs, sizeof(*pdu->pdu_bhs));

        len = pdu_ahs_length(pdu);
        if (len > 0)
                log_errx(1, "protocol error: non-empty AHS");

        len = pdu_data_segment_length(pdu);
        if (len > 0) {
                if (len > (size_t)conn->conn_max_recv_data_segment_length) {
                        log_errx(1, "protocol error: received PDU "
                            "with DataSegmentLength exceeding %d",
                            conn->conn_max_recv_data_segment_length);
                }

                pdu->pdu_data_len = len;
                pdu->pdu_data = malloc(len);
                if (pdu->pdu_data == NULL)
                        log_err(1, "malloc");

                pdu_read(conn, (char *)pdu->pdu_data, pdu->pdu_data_len);

                padding = pdu_padding(pdu);
                if (padding != 0) {
                        assert(padding < sizeof(dummy));
                        pdu_read(conn, (char *)dummy, padding);
                }
        }
}

void
pdu_send(struct pdu *pdu)
{
        struct connection *conn;
        ssize_t ret, total_len;
        size_t padding;
        uint32_t zero = 0;
        struct iovec iov[3];
        int iovcnt;

        conn = pdu->pdu_connection;
        if (conn->conn_use_proxy)
                return (conn->conn_ops->pdu_send_proxy(pdu));

        pdu_set_data_segment_length(pdu, pdu->pdu_data_len);
        iov[0].iov_base = pdu->pdu_bhs;
        iov[0].iov_len = sizeof(*pdu->pdu_bhs);
        total_len = iov[0].iov_len;
        iovcnt = 1;

        if (pdu->pdu_data_len > 0) {
                iov[1].iov_base = pdu->pdu_data;
                iov[1].iov_len = pdu->pdu_data_len;
                total_len += iov[1].iov_len;
                iovcnt = 2;

                padding = pdu_padding(pdu);
                if (padding > 0) {
                        assert(padding < sizeof(zero));
                        iov[2].iov_base = &zero;
                        iov[2].iov_len = padding;
                        total_len += iov[2].iov_len;
                        iovcnt = 3;
                }
        }

        ret = writev(conn->conn_socket, iov, iovcnt);
        if (ret < 0) {
                if (conn->conn_ops->timed_out())
                        log_errx(1, "exiting due to timeout");
                log_err(1, "writev");
        }
        if (ret != total_len)
                log_errx(1, "short write");
}

void
pdu_delete(struct pdu *pdu)
{

        free(pdu->pdu_data);
        free(pdu->pdu_bhs);
        free(pdu);
}