Merge pull request #11597 from opensourcerouting/pimd-packed-member

[mirror_frr.git] / bgpd / bgp_io.c

/* BGP I/O.
 * Implements packet I/O in a pthread.
 * Copyright (C) 2017  Cumulus Networks
 * Quentin Young
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

/* clang-format off */
#include <zebra.h>
#include <pthread.h>            // for pthread_mutex_unlock, pthread_mutex_lock
#include <sys/uio.h>            // for writev

#include "frr_pthread.h"
#include "linklist.h"           // for list_delete, list_delete_all_node, lis...
#include "log.h"                // for zlog_debug, safe_strerror, zlog_err
#include "memory.h"             // for MTYPE_TMP, XCALLOC, XFREE
#include "network.h"            // for ERRNO_IO_RETRY
#include "stream.h"             // for stream_get_endp, stream_getw_from, str...
#include "ringbuf.h"            // for ringbuf_remain, ringbuf_peek, ringbuf_...
#include "thread.h"             // for THREAD_OFF, THREAD_ARG, thread...

#include "bgpd/bgp_io.h"
#include "bgpd/bgp_debug.h"     // for bgp_debug_neighbor_events, bgp_type_str
#include "bgpd/bgp_errors.h"    // for expanded error reference information
#include "bgpd/bgp_fsm.h"       // for BGP_EVENT_ADD, bgp_event
#include "bgpd/bgp_packet.h"    // for bgp_notify_send_with_data, bgp_notify...
#include "bgpd/bgp_trace.h"     // for frrtraces
#include "bgpd/bgpd.h"          // for peer, BGP_MARKER_SIZE, bgp_master, bm
/* clang-format on */

/* forward declarations */
static uint16_t bgp_write(struct peer *);
static uint16_t bgp_read(struct peer *peer, int *code_p);
static void bgp_process_writes(struct thread *);
static void bgp_process_reads(struct thread *);
static bool validate_header(struct peer *);

/* generic i/o status codes */
#define BGP_IO_TRANS_ERR (1 << 0) // EAGAIN or similar occurred
#define BGP_IO_FATAL_ERR (1 << 1) // some kind of fatal TCP error

/* Thread external API ----------------------------------------------------- */

void bgp_writes_on(struct peer *peer)
{
        struct frr_pthread *fpt = bgp_pth_io;
        assert(fpt->running);

        assert(peer->status != Deleted);
        assert(peer->obuf);
        assert(peer->ibuf);
        assert(peer->ibuf_work);
        assert(!peer->t_connect_check_r);
        assert(!peer->t_connect_check_w);
        assert(peer->fd);

        thread_add_write(fpt->master, bgp_process_writes, peer, peer->fd,
                         &peer->t_write);
        SET_FLAG(peer->thread_flags, PEER_THREAD_WRITES_ON);
}

void bgp_writes_off(struct peer *peer)
{
        struct frr_pthread *fpt = bgp_pth_io;
        assert(fpt->running);

        thread_cancel_async(fpt->master, &peer->t_write, NULL);
        THREAD_OFF(peer->t_generate_updgrp_packets);

        UNSET_FLAG(peer->thread_flags, PEER_THREAD_WRITES_ON);
}

void bgp_reads_on(struct peer *peer)
{
        struct frr_pthread *fpt = bgp_pth_io;
        assert(fpt->running);

        assert(peer->status != Deleted);
        assert(peer->ibuf);
        assert(peer->fd);
        assert(peer->ibuf_work);
        assert(peer->obuf);
        assert(!peer->t_connect_check_r);
        assert(!peer->t_connect_check_w);
        assert(peer->fd);

        thread_add_read(fpt->master, bgp_process_reads, peer, peer->fd,
                        &peer->t_read);

        SET_FLAG(peer->thread_flags, PEER_THREAD_READS_ON);
}

void bgp_reads_off(struct peer *peer)
{
        struct frr_pthread *fpt = bgp_pth_io;
        assert(fpt->running);

        thread_cancel_async(fpt->master, &peer->t_read, NULL);
        THREAD_OFF(peer->t_process_packet);
        THREAD_OFF(peer->t_process_packet_error);

        UNSET_FLAG(peer->thread_flags, PEER_THREAD_READS_ON);
}

/* Thread internal functions ----------------------------------------------- */

/*
 * Called from I/O pthread when a file descriptor has become ready for writing.
 */
static void bgp_process_writes(struct thread *thread)
{
        static struct peer *peer;
        peer = THREAD_ARG(thread);
        uint16_t status;
        bool reschedule;
        bool fatal = false;

        if (peer->fd < 0)
                return;

        struct frr_pthread *fpt = bgp_pth_io;

        frr_with_mutex(&peer->io_mtx) {
                status = bgp_write(peer);
                reschedule = (stream_fifo_head(peer->obuf) != NULL);
        }

        /* no problem */
        if (CHECK_FLAG(status, BGP_IO_TRANS_ERR)) {
        }

        /* problem */
        if (CHECK_FLAG(status, BGP_IO_FATAL_ERR)) {
                reschedule = false;
                fatal = true;
        }

        /* If suppress fib pending is enabled, route is advertised to peers when
         * the status is received from the FIB. The delay is added
         * to update group packet generate which will allow more routes to be
         * sent in the update message
         */
        if (reschedule) {
                thread_add_write(fpt->master, bgp_process_writes, peer,
                                 peer->fd, &peer->t_write);
        } else if (!fatal) {
                BGP_UPDATE_GROUP_TIMER_ON(&peer->t_generate_updgrp_packets,
                                          bgp_generate_updgrp_packets);
        }
}

/*
 * Called from I/O pthread when a file descriptor has become ready for reading,
 * or has hung up.
 *
 * We read as much data as possible, process as many packets as we can and
 * place them on peer->ibuf for secondary processing by the main thread.
 */
static void bgp_process_reads(struct thread *thread)
{
        /* clang-format off */
        static struct peer *peer;       // peer to read from
        uint16_t status;                // bgp_read status code
        bool more = true;               // whether we got more data
        bool fatal = false;             // whether fatal error occurred
        bool added_pkt = false;         // whether we pushed onto ->ibuf
        int code = 0;                   // FSM code if error occurred
        /* clang-format on */

        peer = THREAD_ARG(thread);

        if (peer->fd < 0 || bm->terminating)
                return;

        struct frr_pthread *fpt = bgp_pth_io;

        frr_with_mutex(&peer->io_mtx) {
                status = bgp_read(peer, &code);
        }

        /* error checking phase */
        if (CHECK_FLAG(status, BGP_IO_TRANS_ERR)) {
                /* no problem; just don't process packets */
                more = false;
        }

        if (CHECK_FLAG(status, BGP_IO_FATAL_ERR)) {
                /* problem; tear down session */
                more = false;
                fatal = true;

                /* Handle the error in the main pthread, include the
                 * specific state change from 'bgp_read'.
                 */
                thread_add_event(bm->master, bgp_packet_process_error,
                                 peer, code, &peer->t_process_packet_error);
        }

        while (more) {
                /* static buffer for transferring packets */
                /* shorter alias to peer's input buffer */
                struct ringbuf *ibw = peer->ibuf_work;
                /* packet size as given by header */
                uint16_t pktsize = 0;

                /* check that we have enough data for a header */
                if (ringbuf_remain(ibw) < BGP_HEADER_SIZE)
                        break;

                /* check that header is valid */
                if (!validate_header(peer)) {
                        fatal = true;
                        break;
                }

                /* header is valid; retrieve packet size */
                ringbuf_peek(ibw, BGP_MARKER_SIZE, &pktsize, sizeof(pktsize));

                pktsize = ntohs(pktsize);

                /* if this fails we are seriously screwed */
                assert(pktsize <= peer->max_packet_size);

                /*
                 * If we have that much data, chuck it into its own
                 * stream and append to input queue for processing.
                 */
                if (ringbuf_remain(ibw) >= pktsize) {
                        struct stream *pkt = stream_new(pktsize);

                        assert(STREAM_WRITEABLE(pkt) == pktsize);
                        assert(ringbuf_get(ibw, pkt->data, pktsize) == pktsize);
                        stream_set_endp(pkt, pktsize);

                        frrtrace(2, frr_bgp, packet_read, peer, pkt);
                        frr_with_mutex(&peer->io_mtx) {
                                stream_fifo_push(peer->ibuf, pkt);
                        }

                        added_pkt = true;
                } else
                        break;
        }

        /* handle invalid header */
        if (fatal) {
                /* wipe buffer just in case someone screwed up */
                ringbuf_wipe(peer->ibuf_work);
        } else {
                assert(ringbuf_space(peer->ibuf_work) >= peer->max_packet_size);

                thread_add_read(fpt->master, bgp_process_reads, peer, peer->fd,
                                &peer->t_read);
                if (added_pkt)
                        thread_add_event(bm->master, bgp_process_packet,
                                         peer, 0, &peer->t_process_packet);
        }
}

/*
 * Flush peer output buffer.
 *
 * This function pops packets off of peer->obuf and writes them to peer->fd.
 * The amount of packets written is equal to the minimum of peer->wpkt_quanta
 * and the number of packets on the output buffer, unless an error occurs.
 *
 * If write() returns an error, the appropriate FSM event is generated.
 *
 * The return value is equal to the number of packets written
 * (which may be zero).
 */
static uint16_t bgp_write(struct peer *peer)
{
        uint8_t type;
        struct stream *s;
        int update_last_write = 0;
        unsigned int count;
        uint32_t uo = 0;
        uint16_t status = 0;
        uint32_t wpkt_quanta_old;

        int writenum = 0;
        int num;
        unsigned int iovsz;
        unsigned int strmsz;
        unsigned int total_written;
        time_t now;

        wpkt_quanta_old = atomic_load_explicit(&peer->bgp->wpkt_quanta,
                                               memory_order_relaxed);
        struct stream *ostreams[wpkt_quanta_old];
        struct stream **streams = ostreams;
        struct iovec iov[wpkt_quanta_old];

        s = stream_fifo_head(peer->obuf);

        if (!s)
                goto done;

        count = iovsz = 0;
        while (count < wpkt_quanta_old && iovsz < array_size(iov) && s) {
                ostreams[iovsz] = s;
                iov[iovsz].iov_base = stream_pnt(s);
                iov[iovsz].iov_len = STREAM_READABLE(s);
                writenum += STREAM_READABLE(s);
                s = s->next;
                ++iovsz;
                ++count;
        }

        strmsz = iovsz;
        total_written = 0;

        do {
                num = writev(peer->fd, iov, iovsz);

                if (num < 0) {
                        if (!ERRNO_IO_RETRY(errno)) {
                                BGP_EVENT_ADD(peer, TCP_fatal_error);
                                SET_FLAG(status, BGP_IO_FATAL_ERR);
                        } else {
                                SET_FLAG(status, BGP_IO_TRANS_ERR);
                        }

                        break;
                } else if (num != writenum) {
                        unsigned int msg_written = 0;
                        unsigned int ic = iovsz;

                        for (unsigned int i = 0; i < ic; i++) {
                                size_t ss = iov[i].iov_len;

                                if (ss > (unsigned int) num)
                                        break;

                                msg_written++;
                                iovsz--;
                                writenum -= ss;
                                num -= ss;
                        }

                        total_written += msg_written;

                        assert(total_written < count);

                        memmove(&iov, &iov[msg_written],
                                sizeof(iov[0]) * iovsz);
                        streams = &streams[msg_written];
                        stream_forward_getp(streams[0], num);
                        iov[0].iov_base = stream_pnt(streams[0]);
                        iov[0].iov_len = STREAM_READABLE(streams[0]);

                        writenum -= num;
                        num = 0;
                        assert(writenum > 0);
                } else {
                        total_written = strmsz;
                }

        } while (num != writenum);

        /* Handle statistics */
        for (unsigned int i = 0; i < total_written; i++) {
                s = stream_fifo_pop(peer->obuf);

                assert(s == ostreams[i]);

                /* Retrieve BGP packet type. */
                stream_set_getp(s, BGP_MARKER_SIZE + 2);
                type = stream_getc(s);

                switch (type) {
                case BGP_MSG_OPEN:
                        atomic_fetch_add_explicit(&peer->open_out, 1,
                                                  memory_order_relaxed);
                        break;
                case BGP_MSG_UPDATE:
                        atomic_fetch_add_explicit(&peer->update_out, 1,
                                                  memory_order_relaxed);
                        uo++;
                        break;
                case BGP_MSG_NOTIFY:
                        atomic_fetch_add_explicit(&peer->notify_out, 1,
                                                  memory_order_relaxed);
                        /* Double start timer. */
                        peer->v_start *= 2;

                        /* Overflow check. */
                        if (peer->v_start >= (60 * 2))
                                peer->v_start = (60 * 2);

                        /*
                         * Handle Graceful Restart case where the state changes
                         * to Connect instead of Idle.
                         */
                        BGP_EVENT_ADD(peer, BGP_Stop);
                        goto done;

                case BGP_MSG_KEEPALIVE:
                        atomic_fetch_add_explicit(&peer->keepalive_out, 1,
                                                  memory_order_relaxed);
                        break;
                case BGP_MSG_ROUTE_REFRESH_NEW:
                case BGP_MSG_ROUTE_REFRESH_OLD:
                        atomic_fetch_add_explicit(&peer->refresh_out, 1,
                                                  memory_order_relaxed);
                        break;
                case BGP_MSG_CAPABILITY:
                        atomic_fetch_add_explicit(&peer->dynamic_cap_out, 1,
                                                  memory_order_relaxed);
                        break;
                }

                stream_free(s);
                ostreams[i] = NULL;
                update_last_write = 1;
        }

done : {
        now = bgp_clock();
        /*
         * Update last_update if UPDATEs were written.
         * Note: that these are only updated at end,
         *       not per message (i.e., per loop)
         */
        if (uo)
                atomic_store_explicit(&peer->last_update, now,
                                      memory_order_relaxed);

        /* If we TXed any flavor of packet */
        if (update_last_write) {
                atomic_store_explicit(&peer->last_write, now,
                                      memory_order_relaxed);
                peer->last_sendq_ok = now;
        }
}

        return status;
}

/*
 * Reads a chunk of data from peer->fd into peer->ibuf_work.
 *
 * code_p
 *    Pointer to location to store FSM event code in case of fatal error.
 *
 * @return status flag (see top-of-file)
 */
static uint16_t bgp_read(struct peer *peer, int *code_p)
{
        size_t readsize; // how many bytes we want to read
        ssize_t nbytes;  // how many bytes we actually read
        uint16_t status = 0;

        readsize =
                MIN(ringbuf_space(peer->ibuf_work), sizeof(peer->ibuf_scratch));
        nbytes = read(peer->fd, peer->ibuf_scratch, readsize);

        /* EAGAIN or EWOULDBLOCK; come back later */
        if (nbytes < 0 && ERRNO_IO_RETRY(errno)) {
                SET_FLAG(status, BGP_IO_TRANS_ERR);
        } else if (nbytes < 0) {
                /* Fatal error; tear down session */
                flog_err(EC_BGP_UPDATE_RCV,
                         "%s [Error] bgp_read_packet error: %s", peer->host,
                         safe_strerror(errno));

                /* Handle the error in the main pthread. */
                if (code_p)
                        *code_p = TCP_fatal_error;

                SET_FLAG(status, BGP_IO_FATAL_ERR);

        } else if (nbytes == 0) {
                /* Received EOF / TCP session closed */
                if (bgp_debug_neighbor_events(peer))
                        zlog_debug("%s [Event] BGP connection closed fd %d",
                                   peer->host, peer->fd);

                /* Handle the error in the main pthread. */
                if (code_p)
                        *code_p = TCP_connection_closed;

                SET_FLAG(status, BGP_IO_FATAL_ERR);
        } else {
                assert(ringbuf_put(peer->ibuf_work, peer->ibuf_scratch, nbytes)
                       == (size_t)nbytes);
        }

        return status;
}

/*
 * Called after we have read a BGP packet header. Validates marker, message
 * type and packet length. If any of these aren't correct, sends a notify.
 *
 * Assumes that there are at least BGP_HEADER_SIZE readable bytes in the input
 * buffer.
 */
static bool validate_header(struct peer *peer)
{
        uint16_t size;
        uint8_t type;
        struct ringbuf *pkt = peer->ibuf_work;

        static const uint8_t m_correct[BGP_MARKER_SIZE] = {
                0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
                0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
        uint8_t m_rx[BGP_MARKER_SIZE] = {0x00};

        if (ringbuf_peek(pkt, 0, m_rx, BGP_MARKER_SIZE) != BGP_MARKER_SIZE)
                return false;

        if (memcmp(m_correct, m_rx, BGP_MARKER_SIZE) != 0) {
                bgp_notify_send(peer, BGP_NOTIFY_HEADER_ERR,
                                BGP_NOTIFY_HEADER_NOT_SYNC);
                return false;
        }

        /* Get size and type in network byte order. */
        ringbuf_peek(pkt, BGP_MARKER_SIZE, &size, sizeof(size));
        ringbuf_peek(pkt, BGP_MARKER_SIZE + 2, &type, sizeof(type));

        size = ntohs(size);

        /* BGP type check. */
        if (type != BGP_MSG_OPEN && type != BGP_MSG_UPDATE
            && type != BGP_MSG_NOTIFY && type != BGP_MSG_KEEPALIVE
            && type != BGP_MSG_ROUTE_REFRESH_NEW
            && type != BGP_MSG_ROUTE_REFRESH_OLD
            && type != BGP_MSG_CAPABILITY) {
                if (bgp_debug_neighbor_events(peer))
                        zlog_debug("%s unknown message type 0x%02x", peer->host,
                                   type);

                bgp_notify_send_with_data(peer, BGP_NOTIFY_HEADER_ERR,
                                          BGP_NOTIFY_HEADER_BAD_MESTYPE, &type,
                                          1);
                return false;
        }

        /* Minimum packet length check. */
        if ((size < BGP_HEADER_SIZE) || (size > peer->max_packet_size)
            || (type == BGP_MSG_OPEN && size < BGP_MSG_OPEN_MIN_SIZE)
            || (type == BGP_MSG_UPDATE && size < BGP_MSG_UPDATE_MIN_SIZE)
            || (type == BGP_MSG_NOTIFY && size < BGP_MSG_NOTIFY_MIN_SIZE)
            || (type == BGP_MSG_KEEPALIVE && size != BGP_MSG_KEEPALIVE_MIN_SIZE)
            || (type == BGP_MSG_ROUTE_REFRESH_NEW
                && size < BGP_MSG_ROUTE_REFRESH_MIN_SIZE)
            || (type == BGP_MSG_ROUTE_REFRESH_OLD
                && size < BGP_MSG_ROUTE_REFRESH_MIN_SIZE)
            || (type == BGP_MSG_CAPABILITY
                && size < BGP_MSG_CAPABILITY_MIN_SIZE)) {
                if (bgp_debug_neighbor_events(peer)) {
                        zlog_debug("%s bad message length - %d for %s",
                                   peer->host, size,
                                   type == 128 ? "ROUTE-REFRESH"
                                               : bgp_type_str[(int)type]);
                }

                uint16_t nsize = htons(size);

                bgp_notify_send_with_data(peer, BGP_NOTIFY_HEADER_ERR,
                                          BGP_NOTIFY_HEADER_BAD_MESLEN,
                                          (unsigned char *)&nsize, 2);
                return false;
        }

        return true;
}