Instead of waking a listener up then making it sleep, we only wake them up
if we know their rate limit is fine. In the future we could improve on top
of that by deciding to wake a proxy-specific task in XX milliseconds to
take care of enabling the listeners again.
All listeners that are limited by a proxy-specific resource are now
queued at the proxy's and not globally. This allows finer-grained
wakeups when releasing resource.
When an accept() fails because of a connection limit or a memory shortage,
we now disable it and queue it so that it's dequeued only when a connection
is released. This has improved the behaviour of the process near the fd limit
as now a listener with a no connection (eg: stats) will not loop forever
trying to get its connection accepted.
The solution is still not 100% perfect, as we'd like to have this used when
proxy limits are reached (use a per-proxy list) and for safety, we'd need
to have dedicated tasks to periodically re-enable them (eg: to overcome
temporary system-wide resource limitations when no connection is released).
When we fail to create a session because of memory shortage, let's at
least try to send a 500 message directly on the socket. Even if we don't
have any buffers left, the kernel's orphans management will take care of
delivering the message as long as there are socket buffers left.
Patch af5149 introduced an issue which can be detected only on out of
memory conditions : a LIST_DEL() may be performed on an uninitialized
struct member instead of a LIST_INIT() during the accept() phase,
causing crashes and memory corruption to occur.
This issue was detected and diagnosed by the Exceliance R&D team.
This is 1.5-specific and very recent, so no existing deployment should
be impacted.
Never add connections allocated to this sever to a stick-table.
This may be used in conjunction with backup to ensure that
stick-table persistence is disabled for backup servers.
The motivation for this is to allow iteration of all the connections
of a server without the expense of iterating over the global list
of connections.
The first use of this will be to implement an option to close connections
associated with a server when is is marked as being down or in maintenance
mode.
There are some very rare server-to-server applications that abuse the HTTP
protocol and expect the payload phase to be highly interactive, with many
interleaved data chunks in both directions within a single request. This is
absolutely not supported by the HTTP specification and will not work across
most proxies or servers. When such applications attempt to do this through
haproxy, it works but they will experience high delays due to the network
optimizations which favor performance by instructing the system to wait for
enough data to be available in order to only send full packets. Typical
delays are around 200 ms per round trip. Note that this only happens with
abnormal uses. Normal uses such as CONNECT requests nor WebSockets are not
affected.
When "option http-no-delay" is present in either the frontend or the backend
used by a connection, all such optimizations will be disabled in order to
make the exchanges as fast as possible. Of course this offers no guarantee on
the functionality, as it may break at any other place. But if it works via
HAProxy, it will work as fast as possible. This option should never be used
by default, and should never be used at all unless such a buggy application
is discovered. The impact of using this option is an increase of bandwidth
usage and CPU usage, which may significantly lower performance in high
latency environments.
This change should be backported to 1.4 since the first report of such a
misuse was in 1.4. Next patch will also be needed.
Since IPv6 is a different type than IPv4, the pattern fetch functions
src6 and dst6 were added. IPv6 stick-tables can also fetch IPv4 addresses
with src and dst. In this case, the IPv4 addresses are mapped to their
IPv6 counterpart, according to RFC 4291.
Johannes Smith reported some wrong retries count in logs associated with bad
requests. The cause was that the conn_retries field in the stream interface
was only initialized when attempting to connect, but is used when logging,
possibly with an uninitialized value holding last connection's conn_retries.
This could have been avoided by making use of a stream interface initializer.
This bug is 1.5-specific.
It's very annoying that frontend and backend stats are merged because we
don't know what we're observing. For instance, if a "listen" instance
makes use of a distinct backend, it's impossible to know what the bytes_out
means.
Some points take care of not updating counters twice if the backend points
to the frontend, indicating a "listen" instance. The thing becomes more
complex when we try to add support for server side keep-alive, because we
have to maintain a pointer to the backend used for last request, and to
update its stats. But we can't perform such comparisons anymore because
the counters will not match anymore.
So in order to get rid of this situation, let's have both frontend AND
backend stats in the "struct proxy". We simply update the relevant ones
during activity. Some of them are only accounted for in the backend,
while others are just for frontend. Maybe we can improve a bit on that
later, but the essential part is that those counters now reflect what
they really mean.
This one has been removed and is now totally superseded by ->target.
To get the server, one must use target_srv(&s->target) instead of
s->srv now.
The function ensures that non-server targets still return NULL.
s->prev_srv is used by assign_server() only, but all code paths leading
to it now take s->prev_srv from the existing s->srv. So assign_server()
can do that copy into its own stack.
If at one point a different srv is needed, we still have a copy of the
last server on which we failed a connection attempt in s->target.
When dealing with HTTP keep-alive, we'll have to know if we can reuse
an existing connection. For that, we'll have to check if the current
connection was made on the exact same target (referenced in the stream
interface).
Thus, we need to first assign the next target to the session, then
copy it to the stream interface upon connect(). Later we'll check for
equivalence between those two operations.
Now that we have the target pointer and type in the stream interface,
we don't need the applet.handler pointer anymore. That makes the code
somewhat cleaner because we know we're dealing with an applet by checking
its type instead of checking the pointer is not null.
When doing a connect() on a stream interface, some information is needed
from the server and from the backend. In some situations, we don't have
a server and only a backend (eg: peers). In other cases, we know we have
an applet and we don't want to connect to anything, but we'd still like
to have the info about the applet being used.
For this, we now store a pointer to the "target" into the stream interface.
The target describes what's on the other side before trying to connect. It
can be a server, a proxy or an applet for now. Later we'll probably have
descriptors for multiple-stage chains so that the final information may
still be found.
This will help removing many specific cases in the code. It already made
it possible to remove the "srv" and "be" parameters to tcpv4_connect_server().
I/O handlers are still delicate to manipulate. They have no type, they're
just raw functions which have no knowledge of themselves. Let's have them
declared as applets once for all. That way we can have multiple applets
share the same handler functions and we can store their names there. When
we later need to add more parameters (eg: usage stats), we'll be able to
do so in the applets themselves.
The CLI functions has been prefixed with "cli" instead of "stats" as it's
clearly what is going on there.
The applet descriptor in the stream interface should get all the applet
specific data (st0, ...) but this will be done in the next patch so that
we don't pollute this one too much.
When a connection error is encountered on a server and the server's
connection pool is full, pending connections are not woken up because
the current connection is still accounted for on the server, so it
still appears full. This becomes visible on a server which has
"maxconn 1" because the pending connections will only be able to
expire in the queue.
Now we take care of releasing our current connection before trying to
offer it to another pending request, so that the server can accept a
next connection.
This patch should be backported to 1.4.
HTTP pipelining currently needs to monitor the response buffer to wait
for some free space to be able to send a response. It was not possible
for the HTTP analyser to be called based on response buffer activity.
Now we introduce a new buffer flag BF_WAKE_ONCE which is set when the
HTTP request analyser is set on the response buffer and some activity
is detected. This is not clean at all but once of the only ways to fix
the issue before we make it possible to register events for analysers.
Also it appeared that one realign condition did not cover all cases.
Analysers were re-evaluated when some flags were still present in the
buffers, even if they had not changed since previous pass, resulting
in a waste of CPU cycles.
Ensuring that the flags have changed has saved some useless calls :
function min calls per session (before -> after)
http_request_forward_body 5 -> 4
http_response_forward_body 3 -> 2
http_sync_req_state 10 -> 8
http_sync_res_state 8 -> 6
http_resync_states 8 -> 6
The stream_sock's accept() used to close the FD upon error, but this
was also sometimes performed by the frontend's accept() called via the
session's accept(). Those interlaced calls were also responsible for the
spaghetti-looking error unrolling code in session.c and stream_sock.c.
Now the frontend must not close the FD anymore, the session is responsible
for that. It also takes care of just closing the FD or also removing from
the FD lists, depending on its state. The socket-level accept() does not
have to care about that anymore.
Some Alert() messages were remaining in the accept() path, which they
would have no chance to be detected. Remove some of them (the impossible
ones) and replace the relevant ones with send_log() so that the admin
has a chance to catch them.
Enhance pattern convs and fetch argument parsing, now fetchs and convs callbacks used typed args.
Add more details on error messages on parsing pattern expression function.
Update existing pattern convs and fetchs to new proto.
Create stick table key type "binary".
Manage Truncation and padding if pattern's fetch-converted result don't match table key size.
If a read shutdown is encountered on the first packet of a connection
right after the data and the last analyser is unplugged at the same
time, then that last data chunk may never be forwarded. In practice,
right now it cannot happen on requests due to the way they're scheduled,
nor can it happen on responses due to the way their analysers work.
But this behaviour has been observed with new response analysers being
developped.
The reason is that when the read shutdown is encountered and an analyser
is present, data cannot be forwarded but the BF_SHUTW_NOW flag is set.
After that, the analyser gets called and unplugs itself, hoping that
process_session() will automatically forward the data. This does not
happen due to BF_SHUTW_NOW.
Simply removing the test on this flag is not enough because then aborted
requests still get forwarded, due to the forwarding code undoing the
abort.
The solution here consists in checking BF_SHUTR_NOW instead of BF_SHUTW_NOW.
BF_SHUTR_NOW is only set on aborts and remains set until ->shutr() is called.
This is enough to catch recent aborts but not prevent forwarding in other
cases. Maybe a new special buffer flag "BF_ABORT" might be desirable in the
future.
This patch does not need to be backported because older versions don't
have the analyser which make the problem appear.
This counter is incremented for each incoming connection and each active
listener, and is used to prevent haproxy from stopping upon SIGUSR1. It
will thus be possible for some tasks in increment this counter in order
to prevent haproxy from dying until they have completed their job.
The assumption that there was a 1:1 relation between tracked counters and
the frontend/backend role was wrong. It is perfectly possible to track the
track-fe-counters from the backend and the track-be-counters from the
frontend. Thus, in order to reduce confusion, let's remove this useless
{fe,be} reference and simply use {1,2} instead. The keywords have also been
renamed in order to limit confusion. The ACL rule action now becomes
"track-sc{1,2}". The ACLs are now "sc{1,2}_*" instead of "trk{fe,be}_*".
That means that we can reasonably document "sc1" and "sc2" (sticky counters
1 and 2) as sort of patterns that are available during the whole session's
life and use them just like any other pattern.
Having a single tracking pointer for both frontend and backend counters
does not work. Instead let's have one for each. The keyword has changed
to "track-be-counters" and "track-fe-counters", and the ACL "trk_*"
changed to "trkfe_*" and "trkbe_*".
This patch adds support for the following session counters :
- http_req_cnt : HTTP request count
- http_req_rate: HTTP request rate
- http_err_cnt : HTTP request error count
- http_err_rate: HTTP request error rate
The equivalent ACLs have been added to check the tracked counters
for the current session or the counters of the current source.
This counter may be used to track anything. Two sets of ACLs are available
to manage it, one gets its value, and the other one increments its value
and returns it. In the second case, the entry is created if it did not
exist.
Thus it is possible for example to mark a source as being an abuser and
to keep it marked as long as it does not wait for the entry to expire :
# The rules below use gpc0 to track abusers, and reject them if
# a source has been marked as such. The track-counters statement
# automatically refreshes the entry which will not expire until a
# 1-minute silence is respected from the source. The second rule
# evaluates the second part if the first one is true, so GPC0 will
# be increased once the conn_rate is above 100/5s.
stick-table type ip size 200k expire 1m store conn_rate(5s),gpc0
tcp-request track-counters src
tcp-request reject if { trk_get_gpc0 gt 0 }
tcp-request reject if { trk_conn_rate gt 100 } { trk_inc_gpc0 gt 0}
Alternatively, it is possible to let the entry expire even in presence of
traffic by swapping the check for gpc0 and the track-counters statement :
stick-table type ip size 200k expire 1m store conn_rate(5s),gpc0
tcp-request reject if { src_get_gpc0 gt 0 }
tcp-request track-counters src
tcp-request reject if { trk_conn_rate gt 100 } { trk_inc_gpc0 gt 0}
It is also possible not to track counters at all, but entry lookups will
then be performed more often :
stick-table type ip size 200k expire 1m store conn_rate(5s),gpc0
tcp-request reject if { src_get_gpc0 gt 0 }
tcp-request reject if { src_conn_rate gt 100 } { src_inc_gpc0 gt 0}
The '0' at the end of the counter name is there because if we find that more
counters may be useful, other ones will be added.
This function looks up a key, updates its expiration date, or creates
it if it was not found. acl_fetch_src_updt_conn_cnt() was updated to
make use of it.
These counters maintain incoming and outgoing byte rates in a stick-table,
over a period which is defined in the configuration (2 ms to 24 days).
They can be used to detect service abuse and enforce a certain bandwidth
limits per source address for instance, and block if the rate is passed
over. Since 32-bit counters are used to compute the rates, it is important
not to use too long periods so that we don't have to deal with rates above
4 GB per period.
Example :
# block if more than 5 Megs retrieved in 30 seconds from a source.
stick-table type ip size 200k expire 1m store bytes_out_rate(30s)
tcp-request track-counters src
tcp-request reject if { trk_bytes_out_rate gt 5000000 }
# cause a 15 seconds pause to requests from sources in excess of 2 megs/30s
tcp-request inspect-delay 15s
tcp-request content accept if { trk_bytes_out_rate gt 2000000 } WAIT_END
These counters maintain incoming connection rates and session rates
in a stick-table, over a period which is defined in the configuration
(2 ms to 24 days). They can be used to detect service abuse and
enforce a certain accept rate per source address for instance, and
block if the rate is passed over.
Example :
# block if more than 50 requests per 5 seconds from a source.
stick-table type ip size 200k expire 1m store conn_rate(5s),sess_rate(5s)
tcp-request track-counters src
tcp-request reject if { trk_conn_rate gt 50 }
# cause a 3 seconds pause to requests from sources in excess of 20 requests/5s
tcp-request inspect-delay 3s
tcp-request content accept if { trk_sess_rate gt 20 } WAIT_END
Most of the time we'll want to check the connection count of the
criterion we're currently tracking. So instead of duplicating the
src* tests, let's add trk_conn_cnt to report the total number of
connections from the stick table entry currently being tracked.
A nice part of the code was factored, and we should do the same
for the other criteria.
The new "bytes_in_cnt" and "bytes_out_cnt" session counters have been
added. They're automatically updated when session counters are updated.
They can be matched with the "src_kbytes_in" and "src_kbytes_out" ACLs
which apply to the volume per source address. This can be used to deny
access to service abusers.
The new "conn_cur" session counter has been added. It is automatically
updated upon "track XXX" directives, and the entry is touched at the
moment we increment the value so that we don't consider further counter
updates as real updates, otherwise we would end up updating upon completion,
which may not be desired. Probably that some other event counters (eg: HTTP
requests) will have to be updated upon each event though.
This counter can be matched against current session's source address using
the "src_conn_cur" ACL.
It was not normal to have counter fetches in proto_tcp.c. The only
reason was that the key based on the source address was fetched there,
but now we have split the key extraction and data processing, we must
move that to a more appropriate place. Session seems OK since the
counters are all manipulated from here.
Also, since we're precisely counting number of connections with these
ACLs, we rename them src_conn_cnt and src_updt_conn_cnt. This is not
a problem right now since no version was emitted with these keywords.
