haproxy/include/proto/stream.h
Willy Tarreau a68f7629dd BUG/MEDIUM: stick-tables: fix double-decrement of tracked entries
Mailing list participant "mlist" reported negative conn_cur values in
stick tables as the result of "tcp-request connection track-sc". The
reason is that after the stick entry it copied from the session to the
stream, both the session and the stream grab a reference to the entry
and when the stream ends, it decrements one reference and one connection,
then the same is done for the session.

In fact this problem was already encountered slightly differently in the
past and addressed by Thierry using the patch below as it was believed by
then to be only a refcount issue since it was the observable symptom :

   827752e "BUG/MEDIUM: stick-tables: refcount error after copying SC..."

In reality the problem is that the stream must touch neither the refcount
nor the connection count for entries it inherits from the session. While
we have no way to tell whether a track entry was inherited from the session
(since they're simply memcpy'd), it is possible to prevent the stream from
touching an entry that already exists in the session because that's a
guarantee that it was inherited from it.

Note that it may be a temporary fix. Maybe in the future when a session
gives birth to multiple streams we'll face a situation where a session may
be updated to add more tracked entries after instanciating some streams.
The correct long-term fix is to mark some tracked entries as shared or
private (or RO/RW). That will allow the session to track more entries
even after the same trackers are being used by early streams.

No backport is needed, this is only caused by the session/stream split in 1.6.
2015-09-21 17:48:24 +02:00

318 lines
9.6 KiB
C

/*
* include/proto/stream.h
* This file defines everything related to streams.
*
* Copyright (C) 2000-2010 Willy Tarreau - w@1wt.eu
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _PROTO_STREAM_H
#define _PROTO_STREAM_H
#include <common/config.h>
#include <common/memory.h>
#include <types/stream.h>
#include <proto/fd.h>
#include <proto/freq_ctr.h>
#include <proto/stick_table.h>
#include <proto/task.h>
extern struct pool_head *pool2_stream;
extern struct list streams;
extern struct list buffer_wq;
extern struct data_cb sess_conn_cb;
struct stream *stream_new(struct session *sess, struct task *t, enum obj_type *origin);
/* perform minimal intializations, report 0 in case of error, 1 if OK. */
int init_stream();
/* kill a stream and set the termination flags to <why> (one of SF_ERR_*) */
void stream_shutdown(struct stream *stream, int why);
void stream_process_counters(struct stream *s);
void sess_change_server(struct stream *sess, struct server *newsrv);
struct task *process_stream(struct task *t);
void default_srv_error(struct stream *s, struct stream_interface *si);
struct stkctr *smp_fetch_sc_stkctr(struct session *sess, struct stream *strm, const struct arg *args, const char *kw);
int parse_track_counters(char **args, int *arg,
int section_type, struct proxy *curpx,
struct track_ctr_prm *prm,
struct proxy *defpx, char **err);
/* Update the stream's backend and server time stats */
void stream_update_time_stats(struct stream *s);
void __stream_offer_buffers(int rqlimit);
static inline void stream_offer_buffers();
int stream_alloc_work_buffer(struct stream *s);
void stream_release_buffers(struct stream *s);
int stream_alloc_recv_buffer(struct channel *chn);
/* returns the session this stream belongs to */
static inline struct session *strm_sess(const struct stream *strm)
{
return strm->sess;
}
/* returns the frontend this stream was initiated from */
static inline struct proxy *strm_fe(const struct stream *strm)
{
return strm->sess->fe;
}
/* returns the listener this stream was initiated from */
static inline struct listener *strm_li(const struct stream *strm)
{
return strm->sess->listener;
}
/* returns a pointer to the origin of the session which created this stream */
static inline enum obj_type *strm_orig(const struct stream *strm)
{
return strm->sess->origin;
}
/* Remove the refcount from the stream to the tracked counters, and clear the
* pointer to ensure this is only performed once. The caller is responsible for
* ensuring that the pointer is valid first. We must be extremely careful not
* to touch the entries we inherited from the session.
*/
static inline void stream_store_counters(struct stream *s)
{
void *ptr;
int i;
for (i = 0; i < MAX_SESS_STKCTR; i++) {
if (!stkctr_entry(&s->stkctr[i]))
continue;
if (stkctr_entry(&s->sess->stkctr[i]))
continue;
ptr = stktable_data_ptr(s->stkctr[i].table, stkctr_entry(&s->stkctr[i]), STKTABLE_DT_CONN_CUR);
if (ptr)
stktable_data_cast(ptr, conn_cur)--;
stkctr_entry(&s->stkctr[i])->ref_cnt--;
stksess_kill_if_expired(s->stkctr[i].table, stkctr_entry(&s->stkctr[i]));
stkctr_set_entry(&s->stkctr[i], NULL);
}
}
/* Remove the refcount from the stream counters tracked at the content level if
* any, and clear the pointer to ensure this is only performed once. The caller
* is responsible for ensuring that the pointer is valid first. We must be
* extremely careful not to touch the entries we inherited from the session.
*/
static inline void stream_stop_content_counters(struct stream *s)
{
void *ptr;
int i;
for (i = 0; i < MAX_SESS_STKCTR; i++) {
if (!stkctr_entry(&s->stkctr[i]))
continue;
if (stkctr_entry(&s->sess->stkctr[i]))
continue;
if (!(stkctr_flags(&s->stkctr[i]) & STKCTR_TRACK_CONTENT))
continue;
ptr = stktable_data_ptr(s->stkctr[i].table, stkctr_entry(&s->stkctr[i]), STKTABLE_DT_CONN_CUR);
if (ptr)
stktable_data_cast(ptr, conn_cur)--;
stkctr_entry(&s->stkctr[i])->ref_cnt--;
stksess_kill_if_expired(s->stkctr[i].table, stkctr_entry(&s->stkctr[i]));
stkctr_set_entry(&s->stkctr[i], NULL);
}
}
/* Increase total and concurrent connection count for stick entry <ts> of table
* <t>. The caller is responsible for ensuring that <t> and <ts> are valid
* pointers, and for calling this only once per connection.
*/
static inline void stream_start_counters(struct stktable *t, struct stksess *ts)
{
void *ptr;
ptr = stktable_data_ptr(t, ts, STKTABLE_DT_CONN_CUR);
if (ptr)
stktable_data_cast(ptr, conn_cur)++;
ptr = stktable_data_ptr(t, ts, STKTABLE_DT_CONN_CNT);
if (ptr)
stktable_data_cast(ptr, conn_cnt)++;
ptr = stktable_data_ptr(t, ts, STKTABLE_DT_CONN_RATE);
if (ptr)
update_freq_ctr_period(&stktable_data_cast(ptr, conn_rate),
t->data_arg[STKTABLE_DT_CONN_RATE].u, 1);
if (tick_isset(t->expire))
ts->expire = tick_add(now_ms, MS_TO_TICKS(t->expire));
}
/* Enable tracking of stream counters as <stkctr> on stksess <ts>. The caller is
* responsible for ensuring that <t> and <ts> are valid pointers. Some controls
* are performed to ensure the state can still change.
*/
static inline void stream_track_stkctr(struct stkctr *ctr, struct stktable *t, struct stksess *ts)
{
if (stkctr_entry(ctr))
return;
ts->ref_cnt++;
ctr->table = t;
stkctr_set_entry(ctr, ts);
stream_start_counters(t, ts);
}
/* Increase the number of cumulated HTTP requests in the tracked counters */
static void inline stream_inc_http_req_ctr(struct stream *s)
{
void *ptr;
int i;
for (i = 0; i < MAX_SESS_STKCTR; i++) {
struct stkctr *stkctr = &s->stkctr[i];
if (!stkctr_entry(stkctr)) {
stkctr = &s->sess->stkctr[i];
if (!stkctr_entry(stkctr))
continue;
}
ptr = stktable_data_ptr(stkctr->table, stkctr_entry(stkctr), STKTABLE_DT_HTTP_REQ_CNT);
if (ptr)
stktable_data_cast(ptr, http_req_cnt)++;
ptr = stktable_data_ptr(stkctr->table, stkctr_entry(stkctr), STKTABLE_DT_HTTP_REQ_RATE);
if (ptr)
update_freq_ctr_period(&stktable_data_cast(ptr, http_req_rate),
stkctr->table->data_arg[STKTABLE_DT_HTTP_REQ_RATE].u, 1);
}
}
/* Increase the number of cumulated HTTP requests in the backend's tracked
* counters. We don't look up the session since it cannot happen in the bakcend.
*/
static void inline stream_inc_be_http_req_ctr(struct stream *s)
{
void *ptr;
int i;
for (i = 0; i < MAX_SESS_STKCTR; i++) {
struct stkctr *stkctr = &s->stkctr[i];
if (!stkctr_entry(stkctr))
continue;
if (!(stkctr_flags(&s->stkctr[i]) & STKCTR_TRACK_BACKEND))
continue;
ptr = stktable_data_ptr(stkctr->table, stkctr_entry(stkctr), STKTABLE_DT_HTTP_REQ_CNT);
if (ptr)
stktable_data_cast(ptr, http_req_cnt)++;
ptr = stktable_data_ptr(stkctr->table, stkctr_entry(stkctr), STKTABLE_DT_HTTP_REQ_RATE);
if (ptr)
update_freq_ctr_period(&stktable_data_cast(ptr, http_req_rate),
stkctr->table->data_arg[STKTABLE_DT_HTTP_REQ_RATE].u, 1);
}
}
/* Increase the number of cumulated failed HTTP requests in the tracked
* counters. Only 4xx requests should be counted here so that we can
* distinguish between errors caused by client behaviour and other ones.
* Note that even 404 are interesting because they're generally caused by
* vulnerability scans.
*/
static void inline stream_inc_http_err_ctr(struct stream *s)
{
void *ptr;
int i;
for (i = 0; i < MAX_SESS_STKCTR; i++) {
struct stkctr *stkctr = &s->stkctr[i];
if (!stkctr_entry(stkctr)) {
stkctr = &s->sess->stkctr[i];
if (!stkctr_entry(stkctr))
continue;
}
ptr = stktable_data_ptr(stkctr->table, stkctr_entry(stkctr), STKTABLE_DT_HTTP_ERR_CNT);
if (ptr)
stktable_data_cast(ptr, http_err_cnt)++;
ptr = stktable_data_ptr(stkctr->table, stkctr_entry(stkctr), STKTABLE_DT_HTTP_ERR_RATE);
if (ptr)
update_freq_ctr_period(&stktable_data_cast(ptr, http_err_rate),
stkctr->table->data_arg[STKTABLE_DT_HTTP_ERR_RATE].u, 1);
}
}
static void inline stream_add_srv_conn(struct stream *sess, struct server *srv)
{
sess->srv_conn = srv;
LIST_ADD(&srv->actconns, &sess->by_srv);
}
static void inline stream_del_srv_conn(struct stream *sess)
{
if (!sess->srv_conn)
return;
sess->srv_conn = NULL;
LIST_DEL(&sess->by_srv);
}
static void inline stream_init_srv_conn(struct stream *sess)
{
sess->srv_conn = NULL;
LIST_INIT(&sess->by_srv);
}
static inline void stream_offer_buffers()
{
int avail;
if (LIST_ISEMPTY(&buffer_wq))
return;
/* all streams will need 1 buffer, so we can stop waking up streams
* once we have enough of them to eat all the buffers. Note that we
* don't really know if they are streams or just other tasks, but
* that's a rough estimate. Similarly, for each cached event we'll need
* 1 buffer. If no buffer is currently used, always wake up the number
* of tasks we can offer a buffer based on what is allocated, and in
* any case at least one task per two reserved buffers.
*/
avail = pool2_buffer->allocated - pool2_buffer->used - global.tune.reserved_bufs / 2;
if (avail > (int)run_queue)
__stream_offer_buffers(avail);
}
#endif /* _PROTO_STREAM_H */
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/