mngt.c

/*
 * lib/genl/mngt.c              Generic Netlink Management
 *
 *      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) 2003-2006 Thomas Graf <tgraf@suug.ch>
 */

/**
 * @ingroup genl
 * @defgroup genl_mngt Management
 *
 * @par 1) Registering a generic netlink module
 * @code
 * #include <netlink/genl/mngt.h>
 *
 * // First step is to define all the commands being used in
 * // particular generic netlink family. The ID and name are
 * // mandatory to be filled out. A callback function and
 * // most the attribute policy that comes with it must be
 * // defined for commands expected to be issued towards
 * // userspace.
 * static struct genl_cmd foo_cmds[] = {
 *      {
 *              .c_id           = FOO_CMD_NEW,
 *              .c_name         = "NEWFOO" ,
 *              .c_maxattr      = FOO_ATTR_MAX,
 *              .c_attr_policy  = foo_policy,
 *              .c_msg_parser   = foo_msg_parser,
 *      },
 *      {
 *              .c_id           = FOO_CMD_DEL,
 *              .c_name         = "DELFOO" ,
 *      },
 * };
 *
 * // The list of commands must then be integrated into a
 * // struct genl_ops serving as handle for this particular
 * // family.
 * static struct genl_ops my_genl_ops = {
 *      .o_cmds                 = foo_cmds,
 *      .o_ncmds                = ARRAY_SIZE(foo_cmds),
 * };
 *
 * // Using the above struct genl_ops an arbitary number of
 * // cache handles can be associated to it.
 * //
 * // The macro GENL_HDRSIZE() must be used to specify the
 * // length of the header to automatically take headers on
 * // generic layers into account.
 * //
 * // The macro GENL_FAMILY() is used to represent the generic
 * // netlink family id.
 * static struct nl_cache_ops genl_foo_ops = {
 *      .co_name                = "genl/foo",
 *      .co_hdrsize             = GENL_HDRSIZE(sizeof(struct my_hdr)),
 *      .co_msgtypes            = GENL_FAMILY(GENL_ID_GENERATE, "foo"),
 *      .co_genl                = &my_genl_ops,
 *      .co_protocol            = NETLINK_GENERIC,
 *      .co_request_update      = foo_request_update,
 *      .co_obj_ops             = &genl_foo_ops,
 * };
 *
 * // Finally each cache handle for a generic netlink family
 * // must be registered using genl_register().
 * static void __init foo_init(void)
 * {
 *      genl_register(&genl_foo_ops);
 * }
 *
 * // ... respectively unregsted again.
 * static void __exit foo_exit(void)
 * {
 *      genl_unregister(&genl_foo_ops);
 * }
 * @endcode
 * @{
 */

#include <netlink-generic.h>
#include <netlink/netlink.h>
#include <netlink/genl/genl.h>
#include <netlink/genl/mngt.h>
#include <netlink/genl/family.h>
#include <netlink/genl/ctrl.h>
#include <netlink/utils.h>

static NL_LIST_HEAD(genl_ops_list);

static int genl_msg_parser(struct nl_cache_ops *ops, struct sockaddr_nl *who,
                           struct nlmsghdr *nlh, struct nl_parser_param *pp)
{
        int i, err;
        struct genlmsghdr *ghdr;
        struct genl_cmd *cmd;

        ghdr = nlmsg_data(nlh);

        if (ops->co_genl == NULL)
                BUG();

        for (i = 0; i < ops->co_genl->o_ncmds; i++) {
                cmd = &ops->co_genl->o_cmds[i];
                if (cmd->c_id == ghdr->cmd)
                        goto found;
        }

        err = nl_errno(ENOENT);
        goto errout;

found:
        if (cmd->c_msg_parser == NULL)
                err = nl_error(EOPNOTSUPP, "No message parser found.");
        else {
                struct nlattr *tb[cmd->c_maxattr + 1];
                struct genl_info info = {
                        .who = who,
                        .nlh = nlh,
                        .genlhdr = ghdr,
                        .userhdr = genlmsg_data(ghdr),
                        .attrs = tb,
                };

                err = nlmsg_parse(nlh, ops->co_hdrsize, tb, cmd->c_maxattr,
                                  cmd->c_attr_policy);
                if (err < 0)
                        goto errout;

                err = cmd->c_msg_parser(ops, cmd, &info, pp);
        }
errout:
        return err;

}

char *genl_op2name(int family, int op, char *buf, size_t len)
{
        struct genl_ops *ops;
        int i;

        nl_list_for_each_entry(ops, &genl_ops_list, o_list) {
                if (ops->o_family == family) {
                        for (i = 0; i < ops->o_ncmds; i++) {
                                struct genl_cmd *cmd;
                                cmd = &ops->o_cmds[i];

                                if (cmd->c_id == op) {
                                        strncpy(buf, cmd->c_name, len - 1);
                                        return buf;
                                }
                        }
                }
        }

        strncpy(buf, "unknown", len - 1);
        return NULL;
}


/**
 * @name Register/Unregister
 * @{
 */

/**
 * Register generic netlink operations
 * @arg ops             cache operations
 */
int genl_register(struct nl_cache_ops *ops)
{
        int err;

        if (ops->co_protocol != NETLINK_GENERIC) {
                err = nl_error(EINVAL, "cache operations not for protocol " \
                               "NETLINK_GENERIC (protocol=%s)",
                               ops->co_protocol);
                goto errout;
        }

        if (ops->co_hdrsize < GENL_HDRSIZE(0)) {
                err = nl_error(EINVAL, "co_hdrsize too short, probably " \
                               "not including genlmsghdr, minsize=%d",
                               GENL_HDRSIZE(0));
                goto errout;
        }

        if (ops->co_genl == NULL) {
                err = nl_error(EINVAL, "co_genl is NULL, must provide " \
                               "valid genl operations");
                goto errout;
        }

        ops->co_genl->o_cache_ops = ops;
        ops->co_genl->o_name = ops->co_msgtypes[0].mt_name;
        ops->co_genl->o_family = ops->co_msgtypes[0].mt_id;
        ops->co_msg_parser = genl_msg_parser;

        /* FIXME: check for dup */

        nl_list_add_tail(&ops->co_genl->o_list, &genl_ops_list);

        err = nl_cache_mngt_register(ops);
errout:
        return err;
}

/**
 * Unregister generic netlink operations
 * @arg ops             cache operations
 */
void genl_unregister(struct nl_cache_ops *ops)
{
        nl_cache_mngt_unregister(ops);
        nl_list_del(&ops->co_genl->o_list);
}

/** @} */

/**
 * @name Resolving ID/Name
 * @{
 */

static int __genl_ops_resolve(struct nl_cache *ctrl, struct genl_ops *ops)
{
        struct genl_family *family;

        family = genl_ctrl_search_by_name(ctrl, ops->o_name);
        if (family != NULL) {
                ops->o_id = genl_family_get_id(family);
                genl_family_put(family);

                return 0;
        }

        return nl_error(ENOENT, "Unable to find generic netlink family \"%s\"",
                        ops->o_name);
}

int genl_ops_resolve(struct nl_handle *handle, struct genl_ops *ops)
{
        struct nl_cache *ctrl;
        int err;

        ctrl = genl_ctrl_alloc_cache(handle);
        if (ctrl == NULL) {
                err = nl_get_errno();
                goto errout;
        }

        err = __genl_ops_resolve(ctrl, ops);

        nl_cache_free(ctrl);
errout:
        return err;
}

int genl_mngt_resolve(struct nl_handle *handle)
{
        struct nl_cache *ctrl;
        struct genl_ops *ops;
        int err = 0;

        ctrl = genl_ctrl_alloc_cache(handle);
        if (ctrl == NULL) {
                err = nl_get_errno();
                goto errout;
        }

        nl_list_for_each_entry(ops, &genl_ops_list, o_list) {
                err = __genl_ops_resolve(ctrl, ops);
        }

        nl_cache_free(ctrl);
errout:
        return err;
}

/** @} */


/** @} */