| /*! \file mnl.c |
| * |
| * This code integrates libmnl (minimal netlink library) into the osmocom select |
| * loop abstraction. It allows other osmocom libraries or application code to |
| * create netlink sockets and subscribe to netlink events via libmnl. The completion |
| * handler / callbacks are dispatched via libosmocore select loop handling. |
| */ |
| |
| /* |
| * (C) 2020 by Harald Welte <laforge@gnumonks.org> |
| * All Rights Reserved. |
| * |
| * SPDX-License-Identifier: GPL-2.0+ |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| |
| #include <osmocom/core/select.h> |
| #include <osmocom/core/talloc.h> |
| #include <osmocom/core/logging.h> |
| #include <osmocom/core/mnl.h> |
| |
| #include <libmnl/libmnl.h> |
| |
| #include <errno.h> |
| #include <string.h> |
| |
| /* osmo_fd call-back for when RTNL socket is readable */ |
| static int osmo_mnl_fd_cb(struct osmo_fd *ofd, unsigned int what) |
| { |
| uint8_t buf[MNL_SOCKET_BUFFER_SIZE]; |
| struct osmo_mnl *omnl = ofd->data; |
| int rc; |
| |
| if (!(what & OSMO_FD_READ)) |
| return 0; |
| |
| rc = mnl_socket_recvfrom(omnl->mnls, buf, sizeof(buf)); |
| if (rc <= 0) { |
| LOGP(DLGLOBAL, LOGL_ERROR, "Error in mnl_socket_recvfrom(): %s\n", |
| strerror(errno)); |
| return -EIO; |
| } |
| |
| return mnl_cb_run(buf, rc, 0, 0, omnl->mnl_cb, omnl); |
| } |
| |
| /*! create an osmocom-wrapped limnl netlink socket. |
| * \param[in] ctx talloc context from which to allocate |
| * \param[in] bus netlink socket bus ID (see NETLINK_* constants) |
| * \param[in] groups groups of messages to bind/subscribe to |
| * \param[in] mnl_cb callback function called for each incoming message |
| * \param[in] priv opaque private user data |
| * \returns newly-allocated osmo_mnl or NULL in case of error. */ |
| struct osmo_mnl *osmo_mnl_init(void *ctx, int bus, unsigned int groups, mnl_cb_t mnl_cb, void *priv) |
| { |
| struct osmo_mnl *olm = talloc_zero(ctx, struct osmo_mnl); |
| |
| if (!olm) |
| return NULL; |
| |
| olm->priv = priv; |
| olm->mnl_cb = mnl_cb; |
| olm->mnls = mnl_socket_open(bus); |
| if (!olm->mnls) { |
| LOGP(DLGLOBAL, LOGL_ERROR, "Error creating netlink socket for bus %d: %s\n", |
| bus, strerror(errno)); |
| goto out_free; |
| } |
| |
| if (mnl_socket_bind(olm->mnls, groups, MNL_SOCKET_AUTOPID) < 0) { |
| LOGP(DLGLOBAL, LOGL_ERROR, "Error binding netlink socket for bus %d to groups 0x%x: %s\n", |
| bus, groups, strerror(errno)); |
| goto out_close; |
| } |
| |
| osmo_fd_setup(&olm->ofd, mnl_socket_get_fd(olm->mnls), OSMO_FD_READ, osmo_mnl_fd_cb, olm, 0); |
| |
| if (osmo_fd_register(&olm->ofd)) { |
| LOGP(DLGLOBAL, LOGL_ERROR, "Error registering netlinks socket\n"); |
| goto out_close; |
| } |
| |
| return olm; |
| |
| out_close: |
| mnl_socket_close(olm->mnls); |
| out_free: |
| talloc_free(olm); |
| return NULL; |
| } |
| |
| /*! destroy an existing osmocom-wrapped mnl netlink socket: Unregister + close + free. |
| * \param[in] omnl osmo_mnl socket previously returned by osmo_mnl_init() */ |
| void osmo_mnl_destroy(struct osmo_mnl *omnl) |
| { |
| if (!omnl) |
| return; |
| |
| osmo_fd_unregister(&omnl->ofd); |
| mnl_socket_close(omnl->mnls); |
| talloc_free(omnl); |
| } |