It's a bit cumbersome to have to know all possible storable types
from the stats interface. Instead, let's have generic types for
all data, which will facilitate their manipulation.
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
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.
The "_cnt" suffix is already used by ACLs to count various data,
so it makes sense to use the same one in "conn_cnt" instead of
"conn_cum" to count cumulated connections.
This is not a problem because no version was emitted with those
keywords.
Thus we'll try to stick to the following rules :
xxxx_cnt : cumulated event count for criterion xxxx
xxxx_cur : current number of concurrent entries for criterion xxxx
xxxx_rate: event rate for criterion xxxx
This patch adds the ability to set a pointer in the session to an
entry in a stick table which holds various counters related to a
specific pattern.
Right now the syntax matches the target syntax and only the "src"
pattern can be specified, to track counters related to the session's
IPv4 source address. There is a special function to extract it and
convert it to a key. But the goal is to be able to later support as
many patterns as for the stick rules, and get rid of the specific
function.
The "track-counters" directive may only be set in a "tcp-request"
statement right now. Only the first one applies. Probably that later
we'll support multi-criteria tracking for a single session and that
we'll have to name tracking pointers.
No counter is updated right now, only the refcount is. Some subsequent
patches will have to bring that feature.
When an entry already exists, we just need to update its expiration
timer. Let's have a dedicated function for that instead of spreading
open code everywhere.
This change also ensures that an update of an existing sticky session
really leads to an update of its expiration timer, which was apparently
not the case till now. This point needs to be checked in 1.4.
Till now sticky sessions only held server IDs. Now there are other
data types so it is not acceptable anymore to overwrite the server ID
when writing something. The server ID must then only be written from
the caller when appropriate. Doing this has also led to separate
lookup and storage.
This one can be parsed on the "stick-table" after with the "store"
keyword. It will hold the number of connections matching the entry,
for use with ACLs or anything else.
The stick_tables will now be able to store extra data for a same key.
A limited set of extra data types will be defined and for each of them
an offset in the sticky session will be assigned at startup time. All
of this information will be stored in the stick table.
The extra data types will have to be specified after the new "store"
keyword of the "stick-table" directive, which will reserve some space
for them.
pattern.c depended on stick_table while in fact it should be the opposite.
So we move from pattern.c everything related to stick_tables and invert the
dependency. That way the code becomes more logical and intuitive.
The name 'exps' and 'keys' in struct stksess was confusing because it was
the same name as in the table which holds all of them, while they only hold
one node each. Remove the trailing 's' to more clearly identify who's who.
Right now we're only able to store a server ID in a sticky session.
The goal is to be able to store anything whose size is known at startup
time. For this, we store the extra data before the stksess pointer,
using a negative offset. It will then be easy to cumulate multiple
data provided they each have their own offset.
