It was particularly embarrassing that the server timeout was assigned
to buffers during an accept() just to be potentially changed later in
case of a use_backend rule. The frontend side has nothing to do with
server timeouts.
Now we initialize them right after the connect() succeeds. Later this
should change for a unique stream-interface timeout setting only.
Calling sess_establish() upon a successful connect() was essential, but
it was not clearly stated whether it was necessary for an access to an
I/O handler or not. While it would be desired, having it automatically
add the response analyzers is quite a problem, and it breaks HTTP stats.
The solution is thus not to call it for now and to perform the few response
initializations as needed.
For the long term, we need to find a way to specify the analyzers to install
during a stream_int_register_handler() if any.
The connection timeout stored in the buffer has not been used since the
stream interface were introduced. Let's get rid of it as it's one of the
things that complicate factoring of the accept() functions.
We can disable the monitor-net rules on a listener if this flag is not
set in the listener's options. This will be useful when we don't want
to check that fe->addr is set or not for non-TCP frontends.
The new LI_O_TCP_RULES listener option indicates that some TCP rules
must be checked upon accept on this listener. It is now checked by
the frontend and the L4 rules are evaluated only in this case. The
flag is only set when at least one tcp-req rule is present in the
frontend.
The L4 rules check function has now been moved to proto_tcp.c where
it ought to be.
The tcp inspection rules were fast but were only processed after a
schedule had occurred and all resources were allocated. When defending
against DDoS, it's important to be able to apply some protection the
earliest possible instant.
Thus we introduce a new set of rules : tcp-request rules which act
on pure layer4 information (no content). They are evaluated even
before the buffers are allocated for the session, saving as much
time as possible. That way it becomes possible to check an incoming
connection's source IP address against a list of authorized/blocked
networks, and immediately drop the connection.
The rules are checked even before we perform any socket-specific
operation, so that we can optimize the reject case, which will be the
problematic one during a DDoS. The second stream interface and s->txn
are also now initialized after the rules are parsed for the same
reason. All these optimisations have permitted to reach up to 212000
connnections/s with a real rule rejecting based on the source IP
address.
For a long time we had two large accept() functions, one for TCP
sockets instanciating proxies, and another one for UNIX sockets
instanciating the stats interface.
A lot of code was duplicated and both did not work exactly the same way.
Now we have a stream_sock layer accept() called for either TCP or UNIX
sockets, and this function calls the frontend-specific accept() function
which does the rest of the frontend-specific initialisation.
Some code is still duplicated (session & task allocation, stream interface
initialization), and might benefit from having an intermediate session-level
accept() callback to perform such initializations. Still there are some
minor differences that need to be addressed first. For instance, the monitor
nets should only be checked for proxies and not for other connection templates.
Last, we renamed l->private as l->frontend. The "private" pointer in
the listener is only used to store a frontend, so let's rename it to
eliminate this ambiguity. When we later support detached listeners
(eg: FTP), we'll add another field to avoid the confusion.
The 'client.c' file now only contained frontend-specific functions,
so it has naturally be renamed 'frontend.c'. Same for client.h. This
has also been an opportunity to remove some cross references from
files that should not have depended on it.
In the end, this file should contain a protocol-agnostic accept()
code, which would initialize a session, task, etc... based on an
accept() from a lower layer. Right now there are still references
to TCP.
Some ACLs in the client ought to belong to proto_tcp, or protocols.
This file should only contain frontend-specific information and will
be renamed that way in next commit.
Some functions which act on generic buffer contents without being
tcp-specific were historically in proto_tcp.c. This concerns ACLs
and RDP cookies. Those have been moved away to more appropriate
locations. Ideally we should create some new files for each layer6
protocol parser. Let's do that later.
Right now we count the incoming connection only once everything has
been allocated. Since we're planning on considering early ACL rules,
we need to count the connection earlier.
Just like we do on health checks, we should consider that ACLs that make
use of buffer data are layer 6 and not layer 4, because we'll soon have
to distinguish between pure layer 4 ACLs (without any buffer) and these
ones.
If a "stick store-request" rule is present, an entry is preallocated during
the request. However, if there is no response due to an error or to a redir
mode server, we never release it.
By using msg->sol as the beginning of a message, wrong messages were
displayed in debug mode when they were truncated on the last line,
because msg->sol points to the beginning of the last line. Use
data+msg->som instead.
This would only be wrong when the server has not completely responded yet.
Fix two other occurrences of wrong rsp<->sl associations which were harmless
but wrong anyway.
The rate-limit feature relied on a timer to define how long a frontend
must remain idle. It was not considering the pending connections, so it
was almost always ready to be used again and only the accept's limit was
preventing new connections from coming in. By accounting for the pending
connection, we can compute a correct delay and effectively make the
frontend go idle for that (short) time.
Latest BF_READ_ATTACHED fix has unveiled a nice issue with the way
HTTP requests and responses are forwarded. The case where the request
aborts after the response has responded (POST with early response)
forgot to re-enable auto-close on the response. In fact it still
worked thanks to a side effect as long as BF_READ_ATTACHED was there
to force the states to be resynced (and the flags). Since last fix,
the missing auto-close causes CLOSE_WAIT connections when the client
aborts too late during a data transfer.
The right fix consists in considering the situation where the client
experiences an error and to explicitly abort the transfer. There is
no need to wake the response analysers up for that since they'd have
no added value and the analysers flags are cleared. However for a
future usage, that might help (eg: stickiness, ...).
This fix should be backported to 1.4 if the previous one is backported
too. After all the non-reg tests, the risks to see a problem arise
without both patches seems low, and both patches touch sensible areas
of the code. So there's no hurry.
The BF_READ_ATTACHED flag was created to wake analysers once after
a connection was established. It turns out that this flag is never
cleared once set, so even if there is no event, some analysers are
still evaluated for no reason.
The bug was introduced with commit ea38854d34.
It may cause slightly increased CPU usages during data transfers, maybe
even quite noticeable once when transferring transfer-encoded data,
due to the fact that the request analysers are being checked for every
chunk.
This fix must be backported in 1.4 after all non-reg tests have been
completed.
The response analyser was not emptied upon creation of a new session. In
fact it was always zero just because last session leaved it in a zero state,
but in case of shared pools this cannot be guaranteed. The net effect is
that it was possible to have some HTTP (or any other) analysers on the
response path of a stats unix socket, which would reject the response.
This fix must be backported to 1.4.
Commit 4605e3b641cebbdbb2ee5726e5bbc3c03a2d7b5e was not enough, because
connections passing from a TCP frontend to an HTTP backend without any
ACL and via a "default_backend" statement were still working on non-initialized
data. An initialization was missing in the session_set_backend() function, next
to the initialization of hdr_idx.
It's sometimes very useful to be able to monitor a production status in real
time by comparing servers behaviours. Now halog is able to do this when called
with "-srv". It reports various fields for each server found in a log, including
statuses, total reqs, valid reqs, percent of valid reqs, average connection time,
average response time.
It was once reported at least by Dirk Taggesell that the consistent
hash had a very poor distribution, making use of only two servers.
Jeff Persch analysed the code and found the root cause. Consistent
hash makes use of the server IDs, which are completed after the chash
array initialization. This implies that each server which does not
have an explicit "id" parameter will be merged at the same place in
the chash tree and that in the end, only the first or last servers
may be used.
The now obvious fix (thanks to Jeff) is to assign the missing IDs
earlier. However, it should be clearly understood that changing a
hash algorithm on live systems will rebalance the whole system.
Anyway, the only affected users will be the ones for which the
system is quite unbalanced already. The ones who fix their IDs are
not affected at all.
Kudos to Jeff for spotting that bug which got merged 3 days after
the consistent hashing !
When running in pure TCP mode with a traffic inspection rule to detect
HTTP protocol, we have to initialize the HTTP transaction too. The
effect of not doing this was that some incoming connections could have
been matched as carrying HTTP protocol eventhough this was not the case.
Both dispatch and http_proxy modes were broken since 1.4-dev5 when
the adjustment of server health based on response codes was introduced.
In fact, in these modes, s->srv == NULL. The result is a plain segfault.
It should have been noted critical, but the fact that it remained 6
months without being noticed indicates that almost nobody uses these
modes anymore. Also, the crash is immediate upon first request.
Further versions should not be affected anymore since it's planned to
have a dummy server instead of these annoying NULL pointers.
Released version 1.4.6 with the following main changes :
- [BUILD] ebtree: update to v6.0.1 to remove references to dprintf()
- [CLEANUP] acl: make use of eb_is_empty() instead of open coding the tree's emptiness test
- [MINOR] acl: add srv_is_up() to check that a specific server is up or not
- [DOC] add a few precisions about the use of RDP cookies
RDP cookies are not necessarily easy to implement because they require
some configuration on the servers. Add a few hints so that people know
what to check on their servers.
This ACL was missing in complex setups where the status of a remote site
has to be considered in switching decisions. Until there, using a server's
status in an ACL required to have a dedicated backend, which is a bit heavy
when multiple servers have to be monitored.
Released version 1.4.5 with the following main changes :
- [DOC] report minimum kernel version for tproxy in the Makefile
- [MINOR] add the "ignore-persist" option to conditionally ignore persistence
- [DOC] add the "ignore-persist" option to conditionally ignore persistence
- [DOC] fix ignore-persist/force-persist documentation
- [BUG] cttproxy: socket fd leakage in check_cttproxy_version
- [DOC] doc/configuration.txt: fix typos
- [MINOR] option http-pretend-keepalive is both for FEs and BEs
- [MINOR] fix possible crash in debug mode with invalid responses
- [MINOR] halog: add support for statisticts on status codes
- [OPTIM] halog: use a faster zero test in fgets()
- [OPTIM] halog: minor speedup by using unlikely()
- [OPTIM] halog: speed up fgets2-64 by about 10%
- [DOC] refresh the README file and merge the CONTRIB file into it
- [MINOR] acl: support loading values from files
- [MEDIUM] ebtree: upgrade to version 6.0
- [MINOR] acl trees: add flags and union members to store values in trees
- [MEDIUM] acl: add ability to insert patterns in trees
- [MEDIUM] acl: add tree-based lookups of exact strings
- [MEDIUM] acl: add tree-based lookups of networks
- [MINOR] acl: ignore empty lines and comments in pattern files
- [MINOR] stick-tables: add support for "stick on hdr"
It is now possible to stick on an IP address found in a HTTP header. Right
now only the last occurrence of the header can be used, which is generally
enough for most uses. Also, the header extraction rule only knows how to
convert the header to IP. Later it will be usable as a plain string with
an implicit conversion, and the syntax will not change.
Most often, pattern files used by ACLs will be produced by tools
which emit some comments (eg: geolocation lists). It's very annoying
to have to clean the files before using them, and it does not make
much sense to be able to support patterns we already can't input in
the config file. So this patch makes the pattern file loader skip
lines beginning with a sharp and the empty ones, and strips leading
spaces and tabs.
Networks patterns loaded from files for longest match ACL testing
will now be arranged into a prefix tree. This is possible thanks to
the new prefix features in ebtree v6.0. Longest match testing is
slightly slower than exact data maching. However, the measured impact
of running at 42000 requests per second and testing whether the IP
address found in a header belongs to a list of 52000 networks or
not is 3% CPU (increase from 66% to 69%). This is low enough to
permit true geolocation based on huge tables.
Now if some ACL patterns are loaded from a file and the operation is
an exact string match, the data will be arranged in a tree, yielding
a significant performance boost on large data sets. Note that this
only works when case is sensitive.
A new dedicated function, acl_lookup_str(), has been created for this
matching. It is called for every possible input data to test and it
looks the tree up for the data. Since the keywords are loosely typed,
we would have had to add a new columns to all keywords to adjust the
function depending on the type. Instead, we just compare on the match
function. We call acl_lookup_str() when we could use acl_match_str().
The tree lookup is performed first, then the remaining patterns are
attempted if the tree returned nothing.
A quick test shows that when matching a header against a list of 52000
network names, haproxy uses 68% of one core on a core2-duo 3.2 GHz at
42000 requests per second, versus 66% without any rule, which means
only a 2% CPU increase for 52000 rules. Doing the same test without
the tree leads to 100% CPU at 6900 requests/s. Also it was possible
to run the same test at full speed with about 50 sets of 52000 rules
without any measurable performance drop.
The code is now ready to support loading pattern from filesinto trees. For
that, it will be required that the ACL keyword has a flag ACL_MAY_LOOKUP
and that the expr is case sensitive. When that is true, the pattern will
have a flag ACL_PAT_F_TREE_OK to indicate that it is possible to feed the
tree instead of a usual pattern if the parsing function is able to do this.
The tree's root is pre-initialized in the pattern's value so that the
function can easily find it. At that point, if the parsing function decides
to use the tree, it just sets ACL_PAT_F_TREE in the return flags so that
the caller knows the tree has been used and the pattern can be recycled.
That way it will be possible to load some patterns into the tree when it
is compatible, and other ones as linear linked lists. A good example of
this might be IPv4 network entries : right now we support holes in masks,
but this very rare feature is not compatible with binary lookup in trees.
So the parser will be able to decide itself whether the pattern can go to
the tree or not.
If we want to be able to match ACLs against a lot of possible values, we
need to put those values in trees. That will only work for exact matches,
which is normally just what is needed.
Right now, only IPv4 and string matching are planned, but others might come
later.
This version adds support for prefix-based matching of memory blocks,
as well as some code-size and performance improvements on the generic
code. It provides a prefix insertion and longest match which are
compatible with the rest of the common features (walk, duplicates,
delete, ...). This is typically used for network address matching. The
longest-match code is a bit slower than the original memory block
handling code, so they have not been merged together into generic
code. Still it's possible to perform about 10 million networks lookups
per second in a set of 50000, so this should be enough for most usages.
This version also fixes some bugs in parts that were not used, so there
is no need to backport them.
The "acl XXX -f <file>" syntax was supported but nothing was read from
the file. This is now possible. All lines are merged verbatim, even if
they contain spaces (useful for user-agents). There are shortcomings
though. The worst one is that error reporting is too approximative.
Patrick Mézard reported that it was a bit awkward to have the CONTRIB
and contrib entries in the source archive since those can conflict on
case-insensitive file systems. That made a good opportunity to refresh
the README file and to remove that old outdated file.
in cttproxy.c check_cttproxy_version socket is not closed before function
returned. Although it is called only once, I think it is better to close
the socket.
