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