Harald Welte | 53a2fde | 2020-12-01 22:21:14 +0100 | [diff] [blame] | 1 | /*! \file mnl.c |
| 2 | * |
| 3 | * This code integrates libmnl (minimal netlink library) into the osmocom select |
| 4 | * loop abstraction. It allows other osmocom libraries or application code to |
| 5 | * create netlink sockets and subscribe to netlink events via libmnl. The completion |
| 6 | * handler / callbacks are dispatched via libosmocore select loop handling. |
| 7 | */ |
| 8 | |
| 9 | /* |
| 10 | * (C) 2020 by Harald Welte <laforge@gnumonks.org> |
Harald Welte | 6dda35a | 2022-11-09 16:54:50 +0100 | [diff] [blame] | 11 | * All Rights Reserved. |
Harald Welte | 53a2fde | 2020-12-01 22:21:14 +0100 | [diff] [blame] | 12 | * |
| 13 | * SPDX-License-Identifier: GPL-2.0+ |
| 14 | * |
| 15 | * This program is free software; you can redistribute it and/or modify |
| 16 | * it under the terms of the GNU General Public License as published by |
| 17 | * the Free Software Foundation; either version 2 of the License, or |
| 18 | * (at your option) any later version. |
| 19 | * |
| 20 | * This program is distributed in the hope that it will be useful, |
| 21 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 22 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 23 | * GNU General Public License for more details. |
Harald Welte | 53a2fde | 2020-12-01 22:21:14 +0100 | [diff] [blame] | 24 | */ |
| 25 | |
| 26 | #include <osmocom/core/select.h> |
| 27 | #include <osmocom/core/talloc.h> |
| 28 | #include <osmocom/core/logging.h> |
| 29 | #include <osmocom/core/mnl.h> |
| 30 | |
| 31 | #include <libmnl/libmnl.h> |
| 32 | |
| 33 | #include <errno.h> |
| 34 | #include <string.h> |
| 35 | |
| 36 | /* osmo_fd call-back for when RTNL socket is readable */ |
| 37 | static int osmo_mnl_fd_cb(struct osmo_fd *ofd, unsigned int what) |
| 38 | { |
| 39 | uint8_t buf[MNL_SOCKET_BUFFER_SIZE]; |
| 40 | struct osmo_mnl *omnl = ofd->data; |
| 41 | int rc; |
| 42 | |
| 43 | if (!(what & OSMO_FD_READ)) |
| 44 | return 0; |
| 45 | |
| 46 | rc = mnl_socket_recvfrom(omnl->mnls, buf, sizeof(buf)); |
| 47 | if (rc <= 0) { |
| 48 | LOGP(DLGLOBAL, LOGL_ERROR, "Error in mnl_socket_recvfrom(): %s\n", |
| 49 | strerror(errno)); |
| 50 | return -EIO; |
| 51 | } |
| 52 | |
| 53 | return mnl_cb_run(buf, rc, 0, 0, omnl->mnl_cb, omnl); |
| 54 | } |
| 55 | |
| 56 | /*! create an osmocom-wrapped limnl netlink socket. |
| 57 | * \parma[in] ctx talloc context from which to allocate |
| 58 | * \param[in] bus netlink socket bus ID (see NETLINK_* constants) |
| 59 | * \param[in] groups groups of messages to bind/subscribe to |
| 60 | * \param[in] mnl_cb callback function called for each incoming message |
| 61 | * \param[in] priv opaque private user data |
| 62 | * \returns newly-allocated osmo_mnl or NULL in case of error. */ |
| 63 | struct osmo_mnl *osmo_mnl_init(void *ctx, int bus, unsigned int groups, mnl_cb_t mnl_cb, void *priv) |
| 64 | { |
| 65 | struct osmo_mnl *olm = talloc_zero(ctx, struct osmo_mnl); |
| 66 | |
| 67 | if (!olm) |
| 68 | return NULL; |
| 69 | |
| 70 | olm->priv = priv; |
| 71 | olm->mnl_cb = mnl_cb; |
Harald Welte | 26fc913 | 2020-12-04 10:27:41 +0100 | [diff] [blame] | 72 | olm->mnls = mnl_socket_open(bus); |
Harald Welte | 53a2fde | 2020-12-01 22:21:14 +0100 | [diff] [blame] | 73 | if (!olm->mnls) { |
| 74 | LOGP(DLGLOBAL, LOGL_ERROR, "Error creating netlink socket for bus %d: %s\n", |
| 75 | bus, strerror(errno)); |
| 76 | goto out_free; |
| 77 | } |
| 78 | |
| 79 | if (mnl_socket_bind(olm->mnls, groups, MNL_SOCKET_AUTOPID) < 0) { |
| 80 | LOGP(DLGLOBAL, LOGL_ERROR, "Error binding netlink socket for bus %d to groups 0x%x: %s\n", |
| 81 | bus, groups, strerror(errno)); |
| 82 | goto out_close; |
| 83 | } |
| 84 | |
| 85 | osmo_fd_setup(&olm->ofd, mnl_socket_get_fd(olm->mnls), OSMO_FD_READ, osmo_mnl_fd_cb, olm, 0); |
| 86 | |
| 87 | if (osmo_fd_register(&olm->ofd)) { |
| 88 | LOGP(DLGLOBAL, LOGL_ERROR, "Error registering netlinks socket\n"); |
| 89 | goto out_close; |
| 90 | } |
| 91 | |
| 92 | return olm; |
| 93 | |
| 94 | out_close: |
| 95 | mnl_socket_close(olm->mnls); |
| 96 | out_free: |
| 97 | talloc_free(olm); |
| 98 | return NULL; |
| 99 | } |
| 100 | |
| 101 | /*! destroy an existing osmocom-wrapped mnl netlink socket: Unregister + close + free. |
| 102 | * \param[in] omnl osmo_mnl socket previously returned by osmo_mnl_init() */ |
| 103 | void osmo_mnl_destroy(struct osmo_mnl *omnl) |
| 104 | { |
| 105 | if (!omnl) |
| 106 | return; |
| 107 | |
| 108 | osmo_fd_unregister(&omnl->ofd); |
| 109 | mnl_socket_close(omnl->mnls); |
| 110 | talloc_free(omnl); |
| 111 | } |