event.c

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/*
 * @copyright (c) 2016, Network RADIUS SAS (license@networkradius.com)
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *    * Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *    * Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *    * Neither the name of Network RADIUS SAS nor the
 *      names of its contributors may be used to endorse or promote products
 *      derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
/**
 * $Id: 6278db1a8aa116790bf03a75bdd213862a640cfb $
 * @file rlm_sigtran/event.c
 * @brief separate eventing thread to run libosmocore's event loop
 *
 * libosmocore is not thread safe, none of the event loop access functions
 * support synchronised access by multiple threads.
 *
 * Writing a shim layer and overloading the libosmo functions would work
 * but is likely to be fragile.
 *
 * Instead, we run a special thread to handle all requests to SS7 entities.
 *
 * This thread runs the libosmocore event loop, and select()s over the SCTP
 * FDs libosmo* creates, and a pipe we create (to allow communication
 * with worker threads).
 *
 * You might except performance using this model to be terrible.  But the
 * fact that libosmo is entirely async, and there's no heavy crypto being
 * performed, I suspect that this thread is unlikely to become a bottleneck.
 *
 * In future when we have our own async event loop, we can look at submitting
 * patches to libosmocore to allow integration with external event loops.
 *
 * @note We rely on the fact that writes to a pipe of less than PIPE_BUF, are
 *      atomic and not interleaved.
 *
 * @author Arran Cudbard-Bell
 *
 * @copyright 2016 Network RADIUS SAS (license@networkradius.com)
 */
#define LOG_PREFIX "sigtran"
 
#include <osmocom/core/talloc.h>
 
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/io/schedule.h>
#include <unistd.h>
#include <semaphore.h>
#include <signal.h>
 
#include <osmocom/core/logging.h>
#include <osmocom/sccp/sccp_types.h>
#include <osmocom/mtp/mtp_level3.h>
 
#include "libosmo-m3ua/include/bsc_data.h"
#include "libosmo-m3ua/include/sctp_m3ua.h"
#include "sigtran.h"
 
int                     ctrl_pipe[2] = { -1, -1 };      /* Pipes are unidirectional */
static pthread_t        event_thread;
static sem_t            event_thread_running;
static bool             do_exit = false;
 
typedef int (*osmo_cb_func)(struct osmo_fd *fd, unsigned int what);
 
/** Unregister a osmocom_fd from the event loop, and close it
 *
 * @param ofd to unregister.
 * @return 0.
 */
static int _ofd_free(struct osmo_fd *ofd)
{
        osmo_fd_unregister(ofd);
        close(ofd->fd);
        return 0;
}
 
/** Register a new osmocom file descriptor callback
 *
 * @param ctx   to allocate osmocom_fd in.
 * @param fd    to associate with osmocom_fd .
 * @param func  to call when fd becomes readable.
 * @param data  private contextual data.
 * @return
 *      - NULL on error.
 *      - New osmocom_fd on success.
 *        Freeing unregisters osmocom_fd from event loop,
 *        and closes file descriptor.
 */
static struct osmo_fd *ofd_create(TALLOC_CTX *ctx, int fd, osmo_cb_func func, void *data)
{
        struct osmo_fd *ofd;
 
        MEM(ofd = talloc_zero(ctx, struct osmo_fd));
        ofd->fd = fd;
        ofd->when = BSC_FD_READ;
        ofd->cb = func;
        ofd->data = data;
        if (osmo_fd_register(ofd) < 0) {
                ERROR("Failed registering pipe %i", fd);
                return NULL;
        }
        talloc_set_destructor(ofd, _ofd_free);
 
        return ofd;
}
 
/** Shutdown the MTP3 link gracefully if it's being freed
 *
 */
static int _mtp3_link_free(struct mtp_link *mtp3_link)
{
        mtp3_link->shutdown(mtp3_link);
        return 0;
}
 
/** Add a route to an m3ua_association
 *
 */
static int sigtran_m3ua_route_from_conf(UNUSED TALLOC_CTX *ctx,
                                        struct mtp_m3ua_client_link *client,
                                        sigtran_m3ua_route_t *conf)
{
        struct mtp_m3ua_reg_req *route;
 
        size_t i;
 
        route = mtp_m3ua_reg_req_add(client);
        if (!route) return -1;
 
        route->dpc = conf->dpc;
 
        if (conf->opc) {
                struct mtp_m3ua_opc *opc;
 
                for (i = 0; i < talloc_array_length(conf->opc); i++) {
                        opc = talloc_zero(route, struct mtp_m3ua_opc);
                        opc->opc = conf->opc[i];
                        llist_add_tail(&opc->list, &route->opc);
                }
        }
 
        if (conf->si) {
                struct mtp_m3ua_si *si;
 
                for (i = 0; i < talloc_array_length(conf->si); i++) {
                        si = talloc_zero(route, struct mtp_m3ua_si);
                        si->si = conf->si[i];
                        llist_add_tail(&si->list, &route->si);
                }
        }
 
        return 0;
}
 
/** Bring up SCTP/M3UA/MTP3/SCCP
 *
 * @note The final version needs to be much more complex.  We can only have one
 *      event loop per instance of rlm_sigtran, so we need to record link references
 *      and reuse existing SCTP/MTP3 connections where appropriate.
 *
 * @param[in] ctx       to allocate connection data in.
 * @param[out] out      where to write the new sigtran connection.
 * @param[in] conf      for the connection.  Specifies SCTP/M3UA/MTP3/SCCP parameters.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int event_link_up(TALLOC_CTX *ctx, sigtran_conn_t **out, sigtran_conn_conf_t *conf)
{
        struct mtp_link_set             *mtp3_link_set;
        struct mtp_link                 *mtp3_link;
        struct mtp_m3ua_client_link     *m3ua_client;
        socklen_t                       salen;
 
        sigtran_conn_t                  *conn;
 
        conn = talloc_zero(ctx, sigtran_conn_t);
        conn->conf = conf;
 
        /* Temporarily disable until we can fix the osmocom select loop */
#if 0
        conn->bsc_data = bsc_data_alloc(conn);
        talloc_set_destructor(conn, _conn_free);
#else
        conn->bsc_data = bsc_data_alloc(ctx);
#endif
        /*
         *      Create a new link.  This will run over SCTP/M3UA
         */
        MEM(mtp3_link_set = conn->mtp3_link_set = mtp_link_set_alloc(conn->bsc_data));
 
        mtp3_link_set->dpc = conf->mtp3_dpc;    /* Next hop Point Code */
        mtp3_link_set->opc = conf->mtp3_opc;
 
        /*
         *      Patch in our SCCP receive function
         */
        sigtran_sscp_init(conn);
        mtp_link_set_sccp_data_available_cb(mtp3_link_set, sigtran_sccp_incoming);
 
        MEM(mtp3_link = conn->mtp3_link = mtp_link_alloc(mtp3_link_set));
        talloc_set_destructor(mtp3_link, _mtp3_link_free);
        mtp3_link->name = talloc_strdup(mtp3_link, "default");
        mtp3_link->nr = 1;
 
        /*
         *      Sets up the transport for the MTP3 link
         */
        MEM(m3ua_client = mtp3_link->data = mtp_m3ua_client_link_init(mtp3_link));
 
        /*
         *      Setup SCTP src/dst address
         */
        fr_ipaddr_to_sockaddr(&m3ua_client->remote, &salen,
                              &conf->sctp_dst_ipaddr, conf->sctp_dst_port);
        if (conf->sctp_src_ipaddr.af != AF_UNSPEC) {
                fr_ipaddr_to_sockaddr(&m3ua_client->local, &salen,
                                      &conf->sctp_src_ipaddr, conf->sctp_src_port);
        }
 
        /*
         *      Setup M3UA link parameters
         */
        m3ua_client->link_index = conf->m3ua_link_index;
        m3ua_client->routing_context = conf->m3ua_routing_context;
        m3ua_client->ack_timeout = conf->m3ua_ack_timeout;
        m3ua_client->use_beat = conf->m3ua_beat_interval;
 
        /*
         *      Add the route.
         */
        if (conf->m3ua_routes_is_set || conf->m3ua_routes.dpc_is_set) {
                if (sigtran_m3ua_route_from_conf(m3ua_client, m3ua_client, &conf->m3ua_routes) < 0) return -1;
        }
 
        /*
         *      Bring up the MTP3 link
         */
        mtp3_link->reset(mtp3_link);
 
        *out = conn;
 
        return 0;
}
 
/** Take down a sigtran link
 *
 * @note Probably need to do more than just freeing the memory
 */
static int event_link_down(sigtran_conn_t *conn)
{
        talloc_free(conn);
        return 0;
}
 
/** Send response
 *
 * @note Works for both blocking and non-blocking sockets
 *
 * @param[in] ofd to write response notification to.
 * @param[in] txn we're confirming.
 */
int sigtran_event_submit(struct osmo_fd *ofd, sigtran_transaction_t *txn)
{
        uint8_t buff[sizeof(void *)];
        uint8_t *p = buff, *end = buff + sizeof(buff);
 
        memcpy(buff, &txn, sizeof(buff));
 
        for (p = buff; p < end; p++) {
                ssize_t slen;
 
                slen = write(ofd->fd, p, end - p);
                if (slen > 0) {
                        p += slen;
                        continue;
                }
 
                if (errno == EAGAIN) {
                        int     ret;
                        fd_set  error_set;
                        fd_set  write_set;
 
                        DEBUG3("Server core - Got EAGAIN (no buffer space left), waiting for pipe to become writable");
 
                        FD_ZERO(&error_set);
                        FD_ZERO(&write_set);
 
                        FD_SET(ofd->fd, &error_set);
                        FD_SET(ofd->fd, &write_set);
 
                        /*
                         *      Don't let signals mess up the select
                         */
                        do {
                                ret = select(ofd->fd + 1, NULL, &write_set, &error_set, NULL);
                        } while ((ret == -1) && (errno == EINTR));
 
                        /*
                         *      If there wasn't an error try again...
                         */
                        if ((ret > 0) && !FD_ISSET(ofd->fd, &error_set)) continue;
                }
 
                ERROR("Server core - Failed writing to pipe (%i): %s", ofd->fd, fr_syserror(errno));
                return -1;
        }
 
        return 0;
}
 
/** Processes a request for a new pipe from a worker thread
 *
 * @param ofd   for the main ctrl_pipe.
 * @param what  happened.
 * @return
 *      - 0 on success, with pointer written to registration pipe for new osmo_fd.
 *      - -1 on error, with NULL pointer written to registration pipe.
 */
static int event_process_request(struct osmo_fd *ofd, unsigned int what)
{
        sigtran_transaction_t   *txn;
 
        void                    *ptr;
        ssize_t                 len;
 
        if (what & BSC_FD_EXCEPT) {
                ERROR("pipe (%i) closed by osmocom thread, event thread exiting", ofd->fd);
                do_exit = true;
                return -1;
        }
 
        if (!(what & BSC_FD_READ)) return 0;
 
        len = read(ofd->fd, &ptr, sizeof(ptr));
        if (len < 0) {
                ERROR("osmocom thread - Failed reading from pipe (%i): %s", ofd->fd, fr_syserror(errno));
                return -1;
        }
        if (len == 0) {
                DEBUG4("Ignoring zero length read");
                return 0;
        }
        if (len != sizeof(ptr)) {
                ERROR("osmocom thread - Failed reading data from pipe (%i): Too short, "
                      "expected %zu bytes, got %zu bytes", ofd->fd, sizeof(ptr), len);
                ptr = NULL;
 
                if (sigtran_event_submit(ofd, NULL) < 0) {
                fatal_error:
                        DEBUG3("Event loop will exit");
                        do_exit = true;
                        return -1;
                }
 
                return -1;
        }
 
        DEBUG3("osmocom thread - Read %zu bytes from pipe %i (%p)", len, ofd->fd, ptr);
 
        txn = talloc_get_type_abort(ptr, sigtran_transaction_t);
        txn->ctx.ofd = ofd;
        switch (txn->request.type) {
        case SIGTRAN_REQUEST_THREAD_REGISTER:
        {
                struct osmo_fd  *req_ofd;
                int             fd;
 
                fd = *((int *)txn->request.data);       /* Not talloced */
 
                DEBUG3("osmocom thread - Registering req_pipe (%i)", fd);
 
                req_ofd = ofd_create(ofd->data, fd, event_process_request, NULL);
                if (!req_ofd) {
                        txn->response.type = SIGTRAN_RESPONSE_FAIL;
                } else {
                        txn->response.type = SIGTRAN_RESPONSE_OK;
                }
        }
                break;
 
        case SIGTRAN_REQUEST_THREAD_UNREGISTER:
                DEBUG3("osmocom thread - Deregistering req_pipe (%i).  Signalled by worker", ofd->fd);
                txn->response.type = SIGTRAN_RESPONSE_OK;
 
                if (sigtran_event_submit(ofd, txn) < 0) goto fatal_error;
                talloc_free(ofd);       /* Ordering is important */
                return 0;
 
        case SIGTRAN_REQUEST_LINK_UP:
                DEBUG3("osmocom thread - Bringing link up");
                if (event_link_up(ofd->data, (sigtran_conn_t **)&txn->response.data, txn->request.data) < 0) {  /* Struct not talloced */
                        txn->response.type = SIGTRAN_RESPONSE_FAIL;
                } else {
                        txn->response.type = SIGTRAN_RESPONSE_OK;
                }
                break;
 
        case SIGTRAN_REQUEST_LINK_DOWN:
                DEBUG3("osmocom thread - Taking link down");
                if (event_link_down(talloc_get_type_abort(txn->request.data, sigtran_conn_t)) < 0) {
                        txn->response.type = SIGTRAN_RESPONSE_FAIL;
                } else {
                        txn->response.type = SIGTRAN_RESPONSE_OK;
                }
                break;
 
        case SIGTRAN_REQUEST_MAP_SEND_AUTH_INFO:
        {
                sigtran_map_send_auth_info_req_t *req = talloc_get_type_abort(txn->request.data,
                                                                              sigtran_map_send_auth_info_req_t);
                DEBUG3("osmocom thread - Processing map send auth info");
                if (sigtran_tcap_outgoing(NULL, req->conn, txn, ofd) < 0) {
                        txn->response.type = SIGTRAN_RESPONSE_FAIL;
                } else {
                        return 0;       /* Keep caller blocked until we get a response */
                }
        }
                break;
 
        case SIGTRAN_REQUEST_EXIT:
                DEBUG3("osmocom thread - Event loop will exit");
                do_exit = true;
                txn->response.type = SIGTRAN_RESPONSE_OK;
 
                if (sigtran_event_submit(ofd, txn) < 0) goto fatal_error;
                talloc_free(ofd);       /* Ordering is important */
                return 0;
 
#ifndef NDEBUG
        case SIGTRAN_REQUEST_TEST:
                txn->response.type = SIGTRAN_RESPONSE_OK;
                break;
#endif
 
        default:
                fr_assert(0);
                goto fatal_error;
        }
 
        if (sigtran_event_submit(ofd, txn) < 0) goto fatal_error;
 
        return 0;
}
 
/** Enter the libosmo event loop
 *
 * Will run until the thread is killed, or signalled to exit on the ctrl_pipe.
 */
static void *sigtran_event_loop(UNUSED void *instance)
{
        TALLOC_CTX      *ctx = talloc_init_const("sigtran_event_ctx");
 
        fr_assert((ctrl_pipe[0] < 0) && (ctrl_pipe[1] < 0));    /* Ensure only one instance exists */
 
        /*
         *      Patch in libosmo's logging system to ours
         */
        sigtran_log_init(ctx);
 
        if (socketpair(AF_UNIX, SOCK_STREAM, 0, ctrl_pipe) < 0) {
                ERROR("osmocom thread - Failed creating ctrl_pipe: %s", fr_syserror(errno));
                return NULL;
        }
        if (!ofd_create(ctx, ctrl_pipe[1], event_process_request, ctx)) return NULL;
 
        DEBUG2("osmocom thread - Entering event loop, listening on fd %i (client fd %i)", ctrl_pipe[1], ctrl_pipe[0]);
 
        sem_post(&event_thread_running);                /* Up enough to be ok! */
 
        /*
         *      The main event loop.
         */
        while (true) {
                osmo_select_main(0);
                if (do_exit) {
#if 0
                        fd_set  readset, writeset, exceptset;
                        int     high_fd;
 
                        FD_ZERO(&readset);
                        FD_ZERO(&writeset);
                        FD_ZERO(&exceptset);
 
                        high_fd = osmo_fd_fill_fds(&readset, &writeset, &exceptset);
                        if (high_fd == 0) break;
 
                        DEBUG3("osmocom thread - Deferring exit, waiting for fd %i", high_fd);
#else
                        break;
#endif
                }
        }
 
        talloc_free(ctx);       /* Also frees ctrl pipe ofd (which closes ctrl_pipe[1]) */
 
        DEBUG2("osmocom thread - Event loop exiting");
 
        return NULL;
}
 
/** Start the libosmo event loop
 *
 */
int sigtran_event_start(void)
{
        sigset_t sigmask;
 
        sigemptyset(&sigmask);
        sigaddset(&sigmask, SIGCHLD);
 
        sem_init(&event_thread_running, 0, 0);
 
        if (sigtran_sccp_global_init() < 0) {
                ERROR("main thread - Failed initialising SCCP layer");
                return -1;
        }
 
        /*
         *      Reset the signal mask some of the
         *      osmocom code seems to mess with it.
         *
         *      This is so that old Linux kernels
         *      and libkqueue posix/proc work
         *      correctly.
         */
        pthread_sigmask(SIG_BLOCK, &sigmask, NULL);
 
        if (fr_schedule_pthread_create(&event_thread, sigtran_event_loop, NULL) < 0) {
                ERROR("main thread - Failed spawning thread for multiplexer event loop: %s", fr_syserror(errno));
                return -1;
        }
 
        sem_wait(&event_thread_running);
 
#ifndef NDEBUG
        {
                sigtran_transaction_t *txn;
 
                txn = talloc_zero(NULL, sigtran_transaction_t);
                txn->request.type = SIGTRAN_REQUEST_TEST;
 
                if ((sigtran_client_do_transaction(ctrl_pipe[0], txn) < 0) ||
                    (txn->response.type != SIGTRAN_RESPONSE_OK)) {
                        ERROR("main thread - libosmo thread died");
                        talloc_free(txn);
                        return -1;
                }
                talloc_free(txn);
 
                DEBUG2("main thread - libosmo thread responding");
        }
#endif
 
        return 0;
}
 
/** Signal that libosmo should exit
 *
 */
int sigtran_event_exit(void)
{
        sigtran_transaction_t *txn;
 
        txn = talloc_zero(NULL, sigtran_transaction_t);
        txn->request.type = SIGTRAN_REQUEST_EXIT;
 
        if ((sigtran_client_do_transaction(ctrl_pipe[0], txn) < 0) || (txn->response.type != SIGTRAN_RESPONSE_OK)) {
                ERROR("worker - Failed signalling osmocom thread to exit");
                talloc_free(txn);
                return -1;
        }
        talloc_free(txn);
 
        close(ctrl_pipe[0]);
        ctrl_pipe[0] = -1;
        ctrl_pipe[1] = -1;
 
        pthread_join(event_thread, NULL);
 
        sigtran_sccp_global_free();
 
        return 0;
}