Add an extra parametre to conn_create_mux(), "closed_connection".
If a pointer is provided, then let it know if the connection was closed.
Callers have no way to determine that otherwise, and we need to know
that, at least in ssl_sock_io_cb(), as if the connection was closed we
need to return NULL, as the tasklet was free'd, otherwise that can lead
to memory corruption and crashes.
This should be backported if 9240cd4a27
is backported too.
The server's "usesrc" keyword supports among other options "client"
and "clientip". The former means we bind to the client's IP and port
to connect to the server, while the latter means we bind to its IP
only. It's done in two steps, first alloc_bind_address() retrieves
the IP address and port, and second, tcp_connect_server() decides
to either bind to the IP only or IP+port.
The problem comes with idle connection pools, which hash all the
parameters: the hash is calculated before (and ideally withouy) calling
tcp_connect_server(), and it considers the whole struct sockaddr_storage
for the hash, except that both client and clientip entirely fill it with
the client's address. This means that both client and clientip make use
of the source port in the hash calculation, making idle connections
almost not reusable when using "usesrc clientip" while they should for
clients coming from the same source. A work-around is to force the
source port to zero using "tcp-request session set-src-port int(0)" but
it's ugly.
Let's fix this by properly zeroing the port for AF_INET/AF_INET6 addresses.
This can be backported to 2.4. Thanks to Sebastien Gross for providing a
reproducer for this problem.
Support for connection reuse during server checks was implemented
recently. This is activated with the server keyword check-reuse-pool.
Similarly to stream processing via connect_backend(), a connection hash
is calculated when trying to perform reuse for checks. This is necessary
to retrieve for a connection which shares the check connect parameters.
However, idle connections can additionnally be tagged using a
pool-conn-name or SNI under connect_backend(). Check reuse does not test
these values, which prevent to retrieve a matching connection.
Improve this by using "check-sni" value as idle connection hash input
for check reuse. be_calculate_conn_hash() API has been adjusted so that
name value can be passed as input, both when using streams or checks.
Even with the current patch, there is still some scenarii which could
not be covered for checks connection reuse. most notably, when using
dynamic pool-conn-name/SNI value. It is however at least sufficient to
cover simpler cases.
Server instance can be NULL on connect_server(), either when dispatch or
transparent proxy are active. However, in alloc_dst_address() access to
<srv> is safe thanks to SF_ASSIGNED stream flag. Add an ASSUME_NONNULL()
to reflect this state.
This should fix coverity report from github issue #2922.
Since recent commit ee94a6cfc1 ("MINOR: backend: extract conn reuse
from connect_server()") a build warning "set but not used" on the
"reuse" variable is emitted, because indeed the variable is now only
checked when SSL is in use. Let's just mark it as such.
Implement the possibility to reuse idle connections when performing
server checks. This is done thanks to the recently introduced functions
be_calculate_conn_hash() and be_reuse_connection().
One side effect of this change is that be_calculate_conn_hash() can now
be called with a NULL stream instance. As such, part of the functions
are adjusted accordingly.
Note that to simplify configuration, connection reuse is not performed
if any specific check connection parameters are defined on the server
line or via the tcp-check connect rule. This is performed via newly
defined tcpcheck_use_nondefault_connect().
Adjust newly defined be_reuse_connection() API. The stream argument is
removed. This will allows checks to be able to invoke it without relying
on a stream instance.
Following the previous patch, the part directly related to connection
reuse is extracted from connect_server(). It is now define in a new
function be_reuse_connection().
On connection reuse, a hash is first calculated. It is generated from
various connection parameters, to retrieve a matching connection.
Extract hash calculation from connect_server() into a new dedicated
function be_calculate_conn_hash(). The objective is to be able to
perform connection reuse for checks, without connect_server() invokation
which relies on a stream instance.
The main objective of this patch is to remove the stream instance from
conn_backend_get() parameters. This would allow to perform reuse outside
of stream contexts, for example for checks purpose.
Previously, if a server reached its pool-high-count limit, connection
were killed on connect_server() when reuse was not possible. However,
this is now performed even if reuse is done since the following patch :
b3397367dc
MEDIUM: connections: Kill connections even if we are reusing one.
Thus, adjust the related comment to reflect this state.
On backend connection reuse, a hash is calculated from various
parameters, to ensure the selected connection match the requested
parameters. Notably, destination address is one of these parameters.
However, it is only taken into account if using a transparent server
(server address 0.0.0.0).
This may cause issue where an incorrect connection is reused, which is
not targetted to the correct destination address. This may be the case
if a set-dst/set-dst-port is used with a transparent proxy (proxy option
transparent).
The fix is simple enough. Destination address is now always used as
input to the connection reuse hash.
This must be backported up to 2.6. Note that for reverse HTTP to work,
it relies on the following patch, which ensures destination address
remains NULL in this case.
commit e94baf6ca71cb2319610baa74dbf17b9bc602b18
BUG/MINOR: rhttp: fix incorrect dst/dst_port values
Previously, destination address of backend connection was systematically
always reassigned. However, this step is unnecessary on connection
reuse. Indeed, reuse should only be conducted with connection using the
same destination address matching the stream requirements.
This patch removes this unnecessary assignment. It is now only performed
when reuse cannot be conducted and a new connection is instantiated.
Functionnally speaking, this patch should not change anything in theory,
as reuse is performed in conformance with the destination address.
However, it appears that it was not always properly enforced. The
systematic assignment of the destination address hides these issues, so
it is now remove. The identified bogus cases will then be fixed in the
following patches.would
This should be backported up to all stable versions.
With a @rhttp server, connect is not possible, transfer is only possible
via idle connection reuse. The server does not have any network address.
Thus, it is unnecessary to allocate the stream destination address prior
to connection reuse. This patch adjusts this by fixing
alloc_dst_address() to take this into account.
Prior to this patch, alloc_dst_address() would incorrectly assimilate a
@rhttp server with a transparent proxy mode. Thus stream destination
address would be copied from the destination address. Connection adress
would then be rewrote with this incorrect value. This did not impact
connect or reuse as destination addr is only used in idle conn hash
calculation for transparent servers. However, it causes incorrect values
for dst/dst_port samples.
This should be backported up to 2.9.
Since commit 8de8ed4f48 ("MEDIUM: connections: Allow taking over
connections from other tgroups.") we got this partially absurd
build warning when disabling threads:
src/backend.c: In function 'conn_backend_get':
src/backend.c:1371:27: warning: array subscript [0, 0] is outside array bounds of 'struct tgroup_info[1]' [-Warray-bounds]
The reason is that gcc sees that curtgid is not equal to tgid which is
defined as 1 in this case, thus it figures that tgroup_info[curtgid-1]
will be anything but zero and that doesn't fit. It is ridiculous as it
is a perfect case of dead code elimination which should not warrant a
warning. Nevertheless we know we don't need to do this when threads are
disabled and in this case there will not be more than 1 thread group, so
we can happily use that preliminary test to help the compiler eliminate
the dead condition and avoid spitting this warning.
No backport is needed.
As reported in issue #2882, using "no-send-proxy-v2" on a server line does
not properly disable the use of proxy-protocol if it was enabled in a
default-server directive in combination with other PP options. The reason
for this is that the sending of a proxy header is determined by a test on
srv->pp_opts without any distinction, so disabling PPv2 while leaving other
options results in a PPv1 header to be sent.
Let's fix this by explicitly testing for the presence of either send-proxy
or send-proxy-v2 when deciding to send a proxy header.
This can be backported to all versions. Thanks to Andre Sencioles (@asenci)
for reporting the issue and testing the fix.
Maxconn is a bit of a misnomer when it comes to servers, as it doesn't
control the maximum number of connections we establish to a server, but
the maximum number of simultaneous requests. So add "strict-maxconn",
that will make it so we will never establish more connections than
maxconn.
It extends the meaning of the "restricted" setting of
tune.takeover-other-tg-connections, as it will also attempt to get idle
connections from other thread groups if strict-maxconn is set.
Allow haproxy to take over idle connections from other thread groups
than our own. To control that, add a new tunable,
tune.takeover-other-tg-connections. It can have 3 values, "none", where
we won't attempt to get connections from the other thread group (the
default), "restricted", where we only will try to get idle connections
from other thread groups when we're using reverse HTTP, and "full",
where we always try to get connections from other thread groups.
Unless there is a special need, it is advised to use "none" (or
restricted if we're using reverse HTTP) as using connections from other
thread groups may have a performance impact.
Users may have good reasons for using "tune.idle-pool.shared off", one of
them being the cost of moving cache lines between cores, or the kernel-
side locking associated with moving FDs. For this reason, when getting
close to the file descriptors limits, we must not try to kill adjacent
threads' FDs when the sharing of pools is disabled. This is extremely
expensive and kills the performance. We must limit ourselves to our local
FDs only. In such cases, it's up to the users to configure a large enough
maxconn for their usages.
Before this patch, perf top reported 9% CPU usage in connect_server()
onthe trylock used to kill connections when running at 4800 conns for
a global maxconn of 6400 on a 128-thread server. Now it doesn't spend
its time there anymore, and performance has increased by 12%. Note,
it was verified that disabling the locks in such a case has no effect
at all, so better keep them and stay safe.
For both servers and proxies, use one connection queue per thread-group,
instead of only one. Having only one can lead to severe performance
issues on NUMA machines, it is actually trivial to get the watchdog to
trigger on an AMD machine, having a server with a maxconn of 96, and an
injector that uses 160 concurrent connections.
We now have one queue per thread-group, however when dequeueing, we're
dequeuing MAX_SELF_USE_QUEUE (currently 9) pendconns from our own queue,
before dequeueing one from another thread group, if available, to make
sure everybody is still running.
For both proxies and servers, properly calculates queueslength, which is
the total number of element in each queues (as they currently are only
using one queue, it is equivalent to the number of element of that
queue), and use it instead of the queue's length.
There is a small race condition, where a server would check if there is
something left in the proxy queue, and adding something to the proxy
queue. If the server checks just before the stream is added to the queue,
and it no longer has any stream to deal with, then nothing will take
care of the stream, that may stay in the queue forever.
This was worked around with commit 5541d4995d, by checking for that exact
condition after adding the stream to the queue, and trying again to get
a server assigned if it is detected.
That fix lead to multiple infinite loops, that got fixed, but it is not
unlikely that it could happen again. So let's fix the initial problem
differently : a single server may mark itself as ready, and it removes
itself once used. The principle is that when we discover that the just
queued stream is alone with no active request anywhere ot dequeue it,
instead of rebalancing it, it will be assigned to that current "ready"
server that is available to handle it. The extra cost of the atomic ops
is negligible since the situation is super rare.
The "served" field of struct server is used to know how many connections
are currently in use for a server. But served used to be incremented way
after the server was picked, so there were race conditions that could
lead more than maxconn connections to be allocated for one server. To
fix this, increment served way earlier, and make sure at the time that
it never goes past maxconn.
We now should never have more outgoing connections than set by maxconn.
Since commit 53f52e67a0 ("BUG/MEDIUM: queue: always dequeue the backend when
redistributing the last server"), we've got two reports again still showing
the theoretically impossible condition in pendconn_add(), including a single
threaded one.
Thanks to the traces, the issue could be tracked down to the redispatch part.
In fact, in non-determinist LB algorithms (RR, LC, FAS), we don't perform the
LB if there are pending connections in the backend, since it indicates that
previous attempts already failed, so we directly return SRV_STATUS_FULL. And
contrary to a previous belief, it is possible to meet this condition with
be->served==0 when redispatching (and likely with maxconn not greater than
the number of threads).
The problem is that in this case, the entry is queued and then the
pendconn_must_try_again() function checks if any connections are currently
being served to detect if we missed a race, and tries again, but that
situation is not caused by a concurrent thread and will never fix itself,
resulting in the loop.
All that part around pendconn_must_try_again() is still quite brittle, and
a safer approach would involve a sequence counter to detect new arrivals
and dequeues during the pendconn_add() call. But it's more sensitive work,
probably for a later fix.
This fix must be backported wherever the fix above was backported. Thanks
to Patrick Hemmer, as well as Damien Claisse and Basha Mougamadou from
Criteo for their help on tracking this one!
Instead of directly relying on the backend parameter to limit the number of
connection retries, we now use a per-stream value. This value is by default
inherited from the backend value when it is set. So for now, there is no
change except the stream value is used instead of the backend value. But
thanks to this change, it will be possible to dynamically change this value.
Multipath TCP (MPTCP), standardized in RFC8684 [1], is a TCP extension
that enables a TCP connection to use different paths.
Multipath TCP has been used for several use cases. On smartphones, MPTCP
enables seamless handovers between cellular and Wi-Fi networks while
preserving established connections. This use-case is what pushed Apple
to use MPTCP since 2013 in multiple applications [2]. On dual-stack
hosts, Multipath TCP enables the TCP connection to automatically use the
best performing path, either IPv4 or IPv6. If one path fails, MPTCP
automatically uses the other path.
To benefit from MPTCP, both the client and the server have to support
it. Multipath TCP is a backward-compatible TCP extension that is enabled
by default on recent Linux distributions (Debian, Ubuntu, Redhat, ...).
Multipath TCP is included in the Linux kernel since version 5.6 [3]. To
use it on Linux, an application must explicitly enable it when creating
the socket. No need to change anything else in the application.
This attached patch adds MPTCP per address support, to be used with:
mptcp{,4,6}@<address>[:port1[-port2]]
MPTCP v4 and v6 protocols have been added: they are mainly a copy of the
TCP ones, with small differences: names, proto, and receivers lists.
These protocols are stored in __protocol_by_family, as an alternative to
TCP, similar to what has been done with QUIC. By doing that, the size of
__protocol_by_family has not been increased, and it behaves like TCP.
MPTCP is both supported for the frontend and backend sides.
Also added an example of configuration using mptcp along with a backend
allowing to experiment with it.
Note that this is a re-implementation of Bjrn's work from 3 years ago
[4], when haproxy's internals were probably less ready to deal with
this, causing his work to be left pending for a while.
Currently, the TCP_MAXSEG socket option doesn't seem to be supported
with MPTCP [5]. This results in a warning when trying to set the MSS of
sockets in proto_tcp:tcp_bind_listener.
This can be resolved by adding two new variables:
sock_inet(6)_mptcp_maxseg_default that will hold the default
value of the TCP_MAXSEG option. Note that for the moment, this
will always be -1 as the option isn't supported. However, in the
future, when the support for this option will be added, it should
contain the correct value for the MSS, allowing to correctly
set the TCP_MAXSEG option.
Link: https://www.rfc-editor.org/rfc/rfc8684.html [1]
Link: https://www.tessares.net/apples-mptcp-story-so-far/ [2]
Link: https://www.mptcp.dev [3]
Link: https://github.com/haproxy/haproxy/issues/1028 [4]
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/515 [5]
Co-authored-by: Dorian Craps <dorian.craps@student.vinci.be>
Co-authored-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
After checking that a server or backend is full, it remains possible
to call pendconn_add() just after the last pending requests finishes, so
that there's no more connection on the server for very low maxconn (typ 1),
leaving new ones in queue till the timeout.
The approach depends on where the request was queued, though:
- when queued on a server, we can simply detect that we may dequeue
pending requests and wake them up, it will wake our request and
that's fine. This needs to be done in srv_redispatch_connect() when
the server is set.
- when queued on a backend, it means that all servers are done with
their requests. It means that all servers were full before the
check and all were empty after. In practice this will only concern
configs with less servers than threads. It's where the issue was
first spotted, and it's very hard to reproduce with more than one
server. In this case we need to load-balance again in order to find
a spare server (or even to fail). For this, we call the newly added
dedicated function pendconn_must_try_again() that tells whether or
not a blocked pending request was dequeued and needs to be retried.
This should be backported along with pendconn_must_try_again() to all
stable versions, but with extreme care because over time the queue's
locking evolved.
In connect_server() function, there is a test to be able to reuse idle
connections for HTX streams only. Till now, only HTTP connections can be
idle. And this tests was added to be sure to now reuse idle connections for
legacy HTTP streams. But the legacy HTTP was removed in HAProxy-2.1. So we
can safely remove this test.
The related issue is #2502.
Implement pool-conn-name support for idle connection reuse. It replaces
SNI as arbitrary identifier for connections in the idle pool. Thus,
every SNI reference in this context have been replaced.
Main change occurs in connect_server() where pool-conn-name sample fetch
is now prehash to generate idle connection identifier. SNI is now solely
used in the context of SSL for ssl_sock_set_servername().
Update API for PROXY protocol header encoding. Previously, it requires
stream parameter to be set. Change make_proxy_line() and associated
functions to add an extra session parameter. This is useful in context
where no stream is instantiated. For example, this is the case for rhttp
preconnect.
This change allows to extend PROXY v2 TLV encoding. Replace
build_logline() which requires a stream instance and call directly
sess_build_logline().
Note that stream parameter is kept as it is necessary for unique ID
encoding.
This change has no functional change for standard connections. However,
it is necessary to support TLV encoding on rhttp preconnect.
Convert FN_AGE in stat_cols_px[] as generic columns. These values will
be automatically used for dump/preload of a stats-file.
Remove srv_lastsession() / be_lastsession() function which are now
useless as last_sess is calculated via me_generate_field().
last_change was a member present in both proxy and server struct. It is
used as an age statistics to report the last update of the object.
Move last_change into fe_counters/be_counters. This is necessary to be
able to manipulate it through generic stat column and report it into
stats-file.
Note that there is a change for proxy structure with now 2 different
last_change values, on frontend and backend side. Special care was taken
to ensure that the value is initialized only on the proxy side. The
other value is set to 0 unless a listen proxy is instantiated. For the
moment, only backend counter is reported in stats. However, with now two
distinct values, stats could be extended to report it on both side.
Move freq-ctr defined in proxy or server structures into their dedicated
fe_counters/be_counters struct.
Functionnaly no change here. This commit will allow to convert rate
stats column to generic one, which is mandatory to manipulate them in
the stats-file.
This commit is the first one of a series which aims to align counters
usage between frontends/listeners on one side and backends/servers on
the other.
Remove <down_trans> field from proxy structure. Use instead the same
name field from be_counters structure, which is already used for
servers.
As previously mentioned in cd352c0db ("MINOR: log/balance: rename
"log-sticky" to "sticky""), let's define a sticky algorithm that may be
used from any protocol. Sticky algorithm sticks on the same server as
long as it remains available.
The documentation was updated accordingly.
Extend takeover API both for MUX and XPRT with a new boolean argument
<release>. Its purpose is to signal if the connection will be freed
immediately after the takeover, rendering new resources allocation
unnecessary.
For the moment, release argument is always false. However, it will be
set to true on delete server CLI handler to proactively close server
idle connections.
By default, backend connections are attached to a server instance. This
allows to implement connection reuse. However, in some particular cases,
connection cannot be shared accross several clients. These connections
are considered and private and are attached to the session instance
instead.
These private connections are also indexed by the target server to not
mix them. All of this is implemented via a dedicated structure
previously named struct sess_srv_list.
Rename it to better reflect its usage to struct sess_priv_conns. Also
rename its internal members and all of the associated functions.
This commit is only a renaming, thus no functional impact is expected.
set-bc-{mark,tos} actions are pretty similar to set-fc-{mark,tos} to set
mark/tos on packets sent from haproxy to server: set-bc-{mark,tos} actions
act on the whole backend/srv connection: from connect() to connection
teardown, thus they may only be used before the connection to the server
is instantiated, meaning that they are only relevant for request-oriented
rules such as tcp-request or http-request rules. For now their use is
limited to content request rules, because tos and mark informations are
stored directly within the stream, thus it is required that the stream
already exists.
stream flags are used in combination with dedicated stream struct members
variables to pass 'tos' and 'mark' informations so that they are correctly
considered during stream connection assignment logic (prior to connecting
to actually connecting to the server)
'tos' and 'mark' fd sockopts are taken into account in conn hash
parameters for connection reuse mechanism.
The documentation was updated accordingly.
It's useful to be able to recognize certain functions that are often
present in backtraces as they call lower level functions, and for this
they must not be static. Let's remove "static" in front of these
functions:
sc_notify, sc_conn_recv, sc_conn_send, sc_conn_process,
sc_applet_process, back_establish, stream_update_both_sc,
httpclient_applet_io_handler, httpclient_applet_init,
httpclient_applet_release
Instead of the generic MUX_, we now use MUX_CTL_ prefix for all mux_ctl_type
value. This will avoid any ambiguities with other enums, especially with a
new one that will be added to get information on mux streams.
After giving it some thought, it could pretty well happen that other
protocols benefit from the sticky algorithm that some used to emulate
using a "stick-on int(0)" or things like this previously. So better
rename it to "sticky" right now instead of having to keep that "log-"
prefix forever. It's still limited to logs, of course, only the algo
is renamed in the config.
Previous commit renames 'proto_reverse_connect' module to 'proto_rhttp'.
This commits follows this by replacing various custom prefix by 'rhttp_'
to make the code uniform.
Note that 'reverse_' prefix was kept in connection module. This is
because if a new reversable protocol not based on HTTP is implemented,
it may be necessary to reused the same connection function which are
protocol agnostic.
"log-balance" directive was recently introduced to configure the
balancing algorithm to use when in a log backend. However, it is
confusing and it causes issues when used in default section.
In this patch, we take another approach: first we remove the
"log-balance" directive, and instead we rely on existing "balance"
directive to configure log load balancing in log backend.
Some algorithms such as roundrobin can be used as-is in a log backend,
and for log-only algorithms, they are implemented as "log-$name" inside
the "backend" directive.
The documentation was updated accordingly.
If less connections than threads are established on a reverse-http gateway
and these servers have a non-nul pool-min-conn, then conn_backend_get()
will refrain from picking available connections from other threads. But
this makes no sense for protocols for which there is no ->connect(),
since there's no way the current thread will manage to establish its own
connection. For such situations we should always accept to use another
thread's connection. That's precisely what this patch does.
Define a new function srv_add_to_avail_list(). This function is used to
centralize connection insertion in available tree. It reuses a BUG_ON()
statement to ensure the connection is not present in the idle list.
Since the following commit, idle conns are stored in a list as secondary
storage to retrieve them in usage order :
5afcb686b9
MAJOR: connection: purge idle conn by last usage
The list usage has been extended wherever connections lookup are done
both on idle and safe trees. This reduced the code size by replacing a
two tree loops by a single list loop.
LIST_ELEM() is used in this context to retrieve the first idle list
element from the server list head. However, macro usage was wrong due to
an extra '&' operator which returns an invalid connection reference.
This will most of the time caused a crash on conn_delete_from_tree() or
affiliated functions.
This bug only occurs if the FD pool is exhausted and some idle
connections are selected to be killed.
It can be reproduced using the following config and h2load command :
$ h2load -t 8 -c 800 -m 10 -n 800 "http://127.0.0.1:21080/?s=10k"
global
maxconn 100
defaults
mode http
timeout connect 20s
timeout client 20s
timeout server 20s
listen li
bind :21080 proto h2
server nginx 127.99.0.1:30080 proto h1
This bug has been introduced by the above commit. Thus no need to
backport this fix.
Note that LIST_ELEM() macro usage was slightly adjusted also in
srv_migrate_conns_to_remove(). The function used toremove_list instead
of idle_list connection list element. This is not a bug as they are
stored in the same union. However, the new code is clearer as it intends
to move connection from the idle_list only into the toremove_list
mt-list.
Idle connections are both stored in an idle/safe tree and in an idle
list. The list is used as a secondary storage to be able to retrieve
them by usage order.
If a connection is moved into the available tree, it must not be present
in the idle list. A BUG_ON() was written to check this but was placed at
the wrong code section. Fix this by removing the misplaced one and write
new ones for avail_conns tree insertion and lookup.
The impact of this bug is minor as the misplaced BUG_ON() did not seem
to be triggered.
No need to backport.
