/*
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2025 Gleb Smirnoff <glebius@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted providing 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 ``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 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 <stdio.h>
#include <err.h>

#include <netinet/in.h>

#include <netlink/netlink.h>
#include <netlink/netlink_generic.h>
#include <netlink/netlink_snl.h>
#include <netlink/netlink_snl_generic.h>

#include <rpc/types.h>
#include <rpc/xdr.h>
#include <rpc/auth.h>
#include <rpc/clnt.h>
#include <rpc/rpc_msg.h>
#include <rpc/clnt_nl.h>

#include "genl.h"

struct nl_request_parsed {
        uint32_t        group;
        struct nlattr   *data;
};
static const struct snl_attr_parser rpcnl_attr_parser[] = {
#define OUT(field)      offsetof(struct nl_request_parsed, field)
    { .type = RPCNL_REQUEST_GROUP, .off = OUT(group),
       .cb = snl_attr_get_uint32 },
    { .type = RPCNL_REQUEST_BODY, .off = OUT(data), .cb = snl_attr_get_nla },
#undef OUT
};
SNL_DECLARE_PARSER(request_parser, struct genlmsghdr, snl_f_p_empty,
    rpcnl_attr_parser);

void
parser_rpc(struct snl_state *ss __unused, struct nlmsghdr *hdr)
{
        struct nl_request_parsed req;
        struct genlmsghdr *ghdr = (struct genlmsghdr *)(hdr + 1);
        XDR xdrs;
        struct rpc_msg msg;
        struct opaque_auth *oa;
        int32_t *buf;

        if (!snl_parse_nlmsg(NULL, hdr, &request_parser, &req))
                errx(EXIT_FAILURE, "failed to parse RPC message");

        printf("RPC %s: group %8s[0x%2x] length %4u XDR length %4u\n",
            ghdr->cmd == RPCNL_REQUEST ? "request" : "unknown",
            group_name(req.group), req.group,
            hdr->nlmsg_len, NLA_DATA_LEN(req.data));

        xdrmem_create(&xdrs, NLA_DATA(req.data), NLA_DATA_LEN(req.data),
            XDR_DECODE);
        if ((buf = XDR_INLINE(&xdrs, 8 * BYTES_PER_XDR_UNIT)) == NULL) {
                printf("\trunt datagram\n");
                return;
        }

        msg.rm_xid = IXDR_GET_U_INT32(buf);
        msg.rm_direction = IXDR_GET_ENUM(buf, enum msg_type);
        msg.rm_call.cb_rpcvers = IXDR_GET_U_INT32(buf);
        msg.rm_call.cb_prog = IXDR_GET_U_INT32(buf);
        msg.rm_call.cb_vers = IXDR_GET_U_INT32(buf);
        msg.rm_call.cb_proc = IXDR_GET_U_INT32(buf);
        printf("    %5s: xid 0x%-8x program 0x%08xv%u procedure %u\n",
            msg.rm_direction == CALL ? "CALL" : "REPLY", msg.rm_xid,
            msg.rm_call.cb_prog, msg.rm_call.cb_vers, msg.rm_call.cb_proc);

        oa = &msg.rm_call.cb_cred;
        oa->oa_flavor = IXDR_GET_ENUM(buf, enum_t);
        oa->oa_length = (u_int)IXDR_GET_U_INT32(buf);
        if (oa->oa_length) {
                printf("\tcb_cred auth flavor %u length %u\n",
                    oa->oa_flavor, oa->oa_length);
/*
 *      Excerpt from rpc_callmsg.c, if we want to parse cb_cred better.
                if (oa->oa_length > MAX_AUTH_BYTES) {
                        return (FALSE);
                }
                if (oa->oa_base == NULL) {
                        oa->oa_base = (caddr_t)
                            mem_alloc(oa->oa_length);
                        if (oa->oa_base == NULL)
                                return (FALSE);
                }
                buf = XDR_INLINE(&xdrs, RNDUP(oa->oa_length));
                if (buf == NULL) {
                        if (xdr_opaque(&xdrs, oa->oa_base,
                            oa->oa_length) == FALSE) {
                                return (FALSE);
                        }
                } else {
                        memmove(oa->oa_base, buf,
                            oa->oa_length);
                }
*/
        }
        oa = &msg.rm_call.cb_verf;
        buf = XDR_INLINE(&xdrs, 2 * BYTES_PER_XDR_UNIT);
        if (buf == NULL) {
                if (xdr_enum(&xdrs, &oa->oa_flavor) == FALSE ||
                    xdr_u_int(&xdrs, &oa->oa_length) == FALSE)
                        return;
        } else {
                oa->oa_flavor = IXDR_GET_ENUM(buf, enum_t);
                oa->oa_length = (u_int)IXDR_GET_U_INT32(buf);
        }
        if (oa->oa_length) {
                printf("\tcb_verf auth flavor %u length %u\n",
                    oa->oa_flavor, oa->oa_length);
/*
 *      Excerpt from rpc_callmsg.c, if we want to parse cb_verf better.
                if (oa->oa_length > MAX_AUTH_BYTES) {
                        return (FALSE);
                }
                if (oa->oa_base == NULL) {
                        oa->oa_base = (caddr_t)
                            mem_alloc(oa->oa_length);
                        if (oa->oa_base == NULL)
                                return (FALSE);
                }
                buf = XDR_INLINE(&xdrs, RNDUP(oa->oa_length));
                if (buf == NULL) {
                        if (xdr_opaque(&xdrs, oa->oa_base,
                            oa->oa_length) == FALSE) {
                                return (FALSE);
                        }
                } else {
                        memmove(oa->oa_base, buf,
                            oa->oa_length);
                }
*/
        }
}