nf-monitor.c

/*
 * src/nf-monitor.c     Monitor netfilter events
 *
 *      This library is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU Lesser General Public
 *      License as published by the Free Software Foundation version 2.1
 *      of the License.
 *
 * Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
 * Copyright (c) 2007 Philip Craig <philipc@snapgear.com>
 * Copyright (c) 2007 Secure Computing Corporation
 */

#include <netlink/cli/utils.h>
#include <netlink/netfilter/nfnl.h>

static void obj_input(struct nl_object *obj, void *arg)
{
        struct nl_dump_params dp = {
                .dp_type = NL_DUMP_STATS,
                .dp_fd = stdout,
                .dp_dump_msgtype = 1,
        };

        nl_object_dump(obj, &dp);
}

static int event_input(struct nl_msg *msg, void *arg)
{
        if (nl_msg_parse(msg, &obj_input, NULL) < 0)
                fprintf(stderr, "<<EVENT>> Unknown message type\n");

        /* Exit nl_recvmsgs_def() and return to the main select() */
        return NL_STOP;
}

int main(int argc, char *argv[])
{
        struct nl_sock *sock;
        int err;
        int i, idx;

        static const struct {
                enum nfnetlink_groups gr_id;
                const char* gr_name;
        } groups[] = {
                { NFNLGRP_CONNTRACK_NEW, "ct-new" },
                { NFNLGRP_CONNTRACK_UPDATE, "ct-update" },
                { NFNLGRP_CONNTRACK_DESTROY, "ct-destroy" },
                { NFNLGRP_NONE, NULL }
        };

        sock = nl_cli_alloc_socket();
        nl_socket_disable_seq_check(sock);
        nl_socket_modify_cb(sock, NL_CB_VALID, NL_CB_CUSTOM, event_input, NULL);

        if (argc > 1 && !strcasecmp(argv[1], "-h")) {
                printf("Usage: nf-monitor [<groups>]\n");

                printf("Known groups:");
                for (i = 0; groups[i].gr_id != NFNLGRP_NONE; i++)
                        printf(" %s", groups[i].gr_name);
                printf("\n");
                return 2;
        }

        nl_cli_connect(sock, NETLINK_NETFILTER);

        for (idx = 1; argc > idx; idx++) {
                for (i = 0; groups[i].gr_id != NFNLGRP_NONE; i++) {
                        if (strcmp(argv[idx], groups[i].gr_name))
                                continue;

                        err = nl_socket_add_membership(sock, groups[i].gr_id);
                        if (err < 0)
                                nl_cli_fatal(err,
                                             "Unable to add membership: %s",
                                             nl_geterror(err));
                        break;
                }

                if (groups[i].gr_id == NFNLGRP_NONE)
                        nl_cli_fatal(NLE_OBJ_NOTFOUND, "Unknown group: \"%s\"",
                                     argv[idx]);
        }

        while (1) {
                fd_set rfds;
                int fd, retval;

                fd = nl_socket_get_fd(sock);

                FD_ZERO(&rfds);
                FD_SET(fd, &rfds);
                /* wait for an incoming message on the netlink socket */
                retval = select(fd+1, &rfds, NULL, NULL, NULL);

                if (retval) {
                        /* FD_ISSET(fd, &rfds) will be true */
                        nl_recvmsgs_default(sock);
                }
        }

        return 0;
}