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/* 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_io_invalid...
#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 = monotime(NULL);
/*
* 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_io_invalid(peer, BGP_NOTIFY_HEADER_ERR,
BGP_NOTIFY_HEADER_NOT_SYNC, NULL, 0);
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_io_invalid(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_io_invalid(peer, BGP_NOTIFY_HEADER_ERR,
BGP_NOTIFY_HEADER_BAD_MESLEN,
(unsigned char *)&nsize, 2);
return false;
}
return true;
}
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