Commit 47335eee authored by Cédric Le Goater's avatar Cédric Le Goater Committed by Samuel Thibault
Browse files

slirp/ncsi: add checksum support 



The checksum field of a NC-SI packet contains a value that may be
included in each command and response. The verification is optional
but the Linux driver does so when a non-zero value is provided. Let's
extend the model to compute the checksum value and exercise a little
more the Linux driver.

See section "8.2.2.3 - 2's Complement Checksum Compensation" in the
Network Controller Sideband Interface (NC-SI) Specification for more
details.

Signed-off-by: default avatarCédric Le Goater <clg@kaod.org>
Reviewed-by: default avatarPhilippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: default avatarJoel Stanley <joel@jms.id.au>
Signed-off-by: default avatarSamuel Thibault <samuel.thibault@ens-lyon.org>
parent b2d1678f

slirp/ncsi.c

+28 −5
Original line number Diff line number Diff line 
/*

 * NC-SI (Network Controller Sideband Interface) "echo" model

 *

 * Copyright (C) 2016 IBM Corp.

 * Copyright (C) 2016-2018 IBM Corp.

 *

 * This code is licensed under the GPL version 2 or later. See the

 * COPYING file in the top-level directory.
@@ -11,6 +11,23 @@ 


#include "ncsi-pkt.h"



static uint32_t ncsi_calculate_checksum(uint16_t *data, int len)

{

    uint32_t checksum = 0;

    int i;



    /*

     * 32-bit unsigned sum of the NC-SI packet header and NC-SI packet

     * payload interpreted as a series of 16-bit unsigned integer values.

     */

    for (i = 0; i < len; i++) {

        checksum += htons(data[i]);

    }



    checksum = (~checksum + 1);

    return checksum;

}



/* Get Capabilities */

static int ncsi_rsp_handler_gc(struct ncsi_rsp_pkt_hdr *rnh)

{
@@ -101,6 +118,9 @@ void ncsi_input(Slirp *slirp, const uint8_t *pkt, int pkt_len) 
        (ncsi_reply + ETH_HLEN);

    const struct ncsi_rsp_handler *handler = NULL;

    int i;

    int ncsi_rsp_len = sizeof(*nh);

    uint32_t checksum;

    uint32_t *pchecksum;



    memset(ncsi_reply, 0, sizeof(ncsi_reply));
@@ -130,15 +150,18 @@ void ncsi_input(Slirp *slirp, const uint8_t *pkt, int pkt_len) 
            /* TODO: handle errors */

            handler->handler(rnh);

        }

        ncsi_rsp_len += handler->payload;

    } else {

        rnh->common.length = 0;

        rnh->code          = htons(NCSI_PKT_RSP_C_UNAVAILABLE);

        rnh->reason        = htons(NCSI_PKT_RSP_R_UNKNOWN);

    }



    /* TODO: add a checksum at the end of the frame but the specs

     * allows it to be zero */

    /* Add the optional checksum at the end of the frame. */

    checksum = ncsi_calculate_checksum((uint16_t *) rnh, ncsi_rsp_len);

    pchecksum = (uint32_t *)((void *) rnh + ncsi_rsp_len);

    *pchecksum = htonl(checksum);

    ncsi_rsp_len += 4;



    slirp_output(slirp->opaque, ncsi_reply, ETH_HLEN + sizeof(*nh) +

                 (handler ? handler->payload : 0) + 4);

    slirp_output(slirp->opaque, ncsi_reply, ETH_HLEN + ncsi_rsp_len);

}