callback.c

/*
 * (C) 2008-2010 by Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * This program 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; either version 2.1 of the License, or
 * (at your option) any later version.
 */

#include <errno.h>
#include <libmnl/libmnl.h>
#include "internal.h"

static int mnl_cb_noop(const struct nlmsghdr *nlh, void *data)
{
        return MNL_CB_OK;
}

static int mnl_cb_error(const struct nlmsghdr *nlh, void *data)
{
        const struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);

        if (nlh->nlmsg_len < mnl_nlmsg_size(sizeof(struct nlmsgerr))) {
                errno = EBADMSG; 
                return MNL_CB_ERROR;
        }
        /* Netlink subsystems returns the errno value with different signess */
        if (err->error < 0)
                errno = -err->error;
        else
                errno = err->error;

        return err->error == 0 ? MNL_CB_STOP : MNL_CB_ERROR;
}

static int mnl_cb_stop(const struct nlmsghdr *nlh, void *data)
{
        return MNL_CB_STOP;
}

static const mnl_cb_t default_cb_array[NLMSG_MIN_TYPE] = {
        [NLMSG_NOOP]    = mnl_cb_noop,
        [NLMSG_ERROR]   = mnl_cb_error,
        [NLMSG_DONE]    = mnl_cb_stop,
        [NLMSG_OVERRUN] = mnl_cb_noop,
};

static inline int
__mnl_cb_run(const void *buf, size_t numbytes, unsigned int seq,
             unsigned int portid, mnl_cb_t cb_data, void *data,
             mnl_cb_t *cb_ctl_array, unsigned int cb_ctl_array_len)
{
        int ret = MNL_CB_OK, len = numbytes;
        const struct nlmsghdr *nlh = buf;

        while (mnl_nlmsg_ok(nlh, len)) {
                /* check message source */
                if (!mnl_nlmsg_portid_ok(nlh, portid)) {
                        errno = ESRCH;
                        return -1;
                }
                /* perform sequence tracking */
                if (!mnl_nlmsg_seq_ok(nlh, seq)) {
                        errno = EPROTO;
                        return -1;
                }

                /* netlink data message handling */
                if (nlh->nlmsg_type >= NLMSG_MIN_TYPE) { 
                        if (cb_data){
                                ret = cb_data(nlh, data);
                                if (ret <= MNL_CB_STOP)
                                        goto out;
                        }
                } else if (nlh->nlmsg_type < cb_ctl_array_len) {
                        if (cb_ctl_array && cb_ctl_array[nlh->nlmsg_type]) {
                                ret = cb_ctl_array[nlh->nlmsg_type](nlh, data);
                                if (ret <= MNL_CB_STOP)
                                        goto out;
                        }
                } else if (default_cb_array[nlh->nlmsg_type]) {
                        ret = default_cb_array[nlh->nlmsg_type](nlh, data);
                        if (ret <= MNL_CB_STOP)
                                goto out;
                }
                nlh = mnl_nlmsg_next(nlh, &len);
        }
out:
        return ret;
}

EXPORT_SYMBOL int
mnl_cb_run2(const void *buf, size_t numbytes, unsigned int seq,
            unsigned int portid, mnl_cb_t cb_data, void *data,
            mnl_cb_t *cb_ctl_array, unsigned int cb_ctl_array_len)
{
        return __mnl_cb_run(buf, numbytes, seq, portid, cb_data, data,
                            cb_ctl_array, cb_ctl_array_len);
}

EXPORT_SYMBOL int
mnl_cb_run(const void *buf, size_t numbytes, unsigned int seq,
           unsigned int portid, mnl_cb_t cb_data, void *data)
{
        return __mnl_cb_run(buf, numbytes, seq, portid, cb_data, data, NULL, 0);
}