Released version 3.4-dev6 with the following main changes :
- CLEANUP: acme: remove duplicate includes
- BUG/MINOR: proxy: detect strdup error on server auto SNI
- BUG/MINOR: server: set auto SNI for dynamic servers
- BUG/MINOR: server: enable no-check-sni-auto for dynamic servers
- MINOR: haterm: provide -b and -c options (RSA key size, ECDSA curves)
- MINOR: haterm: add long options for QUIC and TCP "bind" settings
- BUG/MINOR: haterm: missing allocation check in copy_argv()
- BUG/MINOR: quic: fix counters used on BE side
- MINOR: quic: add BUG_ON() on half_open_conn counter access from BE
- BUG/MINOR: quic/h3: display QUIC/H3 backend module on HTML stats
- BUG/MINOR: acme: acme_ctx_destroy() leaks auth->dns
- BUG/MINOR: acme: wrong labels logic always memprintf errmsg
- MINOR: ssl: clarify error reporting for unsupported keywords
- BUG/MINOR: acme: fix incorrect number of arguments allowed in config
- CLEANUP: haterm: remove unreachable labels hstream_add_data()
- CLEANUP: haterm: avoid static analyzer warnings about rand() use
- CLEANUP: ssl: Remove a useless variable from ssl_gen_x509()
- CI: use the latest docker for QUIC Interop
- CI: remove redundant "halog" compilation
- CLENAUP: cfgparse: accept-invalid-http-* does not support "no"/"defaults"
- BUG/MEDIUM: spoe: Acquire context buffer in applet before consuming a frame
- MINOR: traces: always mark trace_source as thread-aligned
- MINOR: ncbmbuf: improve itbmap_next() code
- MINOR: proxy: improve code when checking server name conflicts
- MINOR: quic: add a new metric for ncbuf failures
- BUG/MINOR: haterm: cannot reset default "haterm" mode
- BUG/MEDIUM: cpu-topo: Distribute CPUs fairly across groups
- BUG/MINOR: quic: missing app ops init during backend 0-RTT sessions
- CLEANUP: ssl: remove outdated comments
- MINOR: mux-h2: also count glitches on invalid trailers
- MINOR: mux-h2: add a new setting, "tune.h2.log-errors" to tweak error logging
- BUG/MEDIUM: mux-h2: make sure to always report pending errors to the stream
- BUG/MINOR: server: adjust initialization order for dynamic servers
- CLEANUP: tree-wide: drop a few useless null-checks before free()
- CLEANUP: quic-stats: include counters from quic_stats
- REORG: stats/counters: move extra_counters to counters not stats
- CLEANUP: stats: drop stats.h / stats-t.h where not needed
- MEDIUM: counters: change the fill_stats() API to pass the module and extra_counters
- CLEANUP: counters: only retrieve zeroes for unallocated extra_counters
- MEDIUM: counters: add a dedicated storage for extra_counters in various structs
- MINOR: counters: store a tgroup step for extra_counters to access multiple tgroups
- MEDIUM: counters: store the number of thread groups accessing extra_counters
- MINOR: counters: add EXTRA_COUNTERS_BASE() to retrieve extra_counters base storage
- MEDIUM: counters: return aggregate extra counters in ->fill_stats()
- MEDIUM: counters: make EXTRA_COUNTERS_GET() consider tgid
- BUG/MINOR: call EXTRA_COUNTERS_FREE() before srv_free_params() in srv_drop()
- MINOR: promex: test applet resume in stress mode
- BUG/MINOR: promex: fix server iteration when last server is deleted
- BUG/MINOR: proxy: add dynamic backend into ID tree
- MINOR: proxy: convert proxy flags to uint
- MINOR: server: refactor srv_detach()
- MINOR: proxy: define a basic "del backend" CLI
- MINOR: proxy: define proxy watcher member
- MINOR: stats: protect proxy iteration via watcher
- MINOR: promex: use watcher to iterate over backend instances
- MINOR: lua: use watcher for proxies iterator
- MINOR: proxy: add refcount to proxies
- MINOR: proxy: rename default refcount to avoid confusion
- MINOR: server: take proxy refcount when deleting a server
- MINOR: lua: handle proxy refcount
- MINOR: proxy: prevent backend removal when unsupported
- MINOR: proxy: prevent deletion of backend referenced by config elements
- MINOR: proxy: prevent backend deletion if server still exists in it
- MINOR: server: mark backend removal as forbidden if QUIC was used
- MINOR: cli: implement wait on be-removable
- MINOR: proxy: add comment for defaults_px_ref/unref_all()
- MEDIUM: proxy: add lock for global accesses during proxy free
- MEDIUM: proxy: add lock for global accesses during default free
- MINOR: proxy: use atomic ops for default proxy refcount
- MEDIUM: proxy: implement backend deletion
- REGTESTS: add a test on "del backend"
- REGTESTS: complete "del backend" with unnamed defaults ref free
- BUG/MINOR: hlua: fix return with push nil on proxy check
- BUG/MEDIUM: stream: Handle TASK_WOKEN_RES as a stream event
- MINOR: quic: use signed char type for ALPN manipulation
- MINOR: quic/h3: reorganize stream reject after MUX closure
- MINOR: mux-quic: add function for ALPN to app-ops conversion
- MEDIUM: quic/mux-quic: adjust app-ops install
- MINOR: quic: use server cache for ALPN on BE side
- BUG/MEDIUM: hpack: correctly deal with too large decoded numbers
- BUG/MAJOR: qpack: unchecked length passed to huffman decoder
- BUG/MINOR: qpack: fix 1-byte OOB read in qpack_decode_fs_pfx()
- BUG/MINOR: quic: fix OOB read in preferred_address transport parameter
- BUG/MEDIUM: qpack: correctly deal with too large decoded numbers
- BUG/MINOR: hlua: Properly enable/disable line receives from HTTP applet
- BUG/MEDIUM: hlua: Fix end of request detection when retrieving payload
- BUG/MINOR: hlua: Properly enable/disable receives for TCP applets
- MINOR: htx: Add a function to retrieve the HTTP version from a start-line
- MINOR: h1-htx: Reports non-HTTP version via dedicated flags
- BUG/MINOR: h1-htx: Be sure that H1 response version starts by "HTTP/"
- MINOR: http-ana: Save the message version in the http_msg structure
- MEDIUM: http-fetch: Rework how HTTP message version is retrieved
- MEDIUM: http-ana: Use the version of the opposite side for internal messages
- DEBUG: stream: Display the currently running rule in stream dump
- MINOR: filters: Use filter API as far as poissible to break loops on filters
- MINOR: filters: Set last_entity when a filter fails on stream_start callback
- MINOR: stream: Display the currently running filter per channel in stream dump
- DOC: config: Use the right alias for %B
- BUG/MINOR: channel: Increase the stconn bytes_in value in channel_add_input()
- BUG/MINOR: sample: Fix sample to retrieve the number of bytes received and sent
- BUG/MINOR: http-ana: Increment scf bytes_out value if an haproxy error is sent
- BUG/MAJOR: fcgi: Fix param decoding by properly checking its size
- BUG/MAJOR: resolvers: Properly lowered the names found in DNS response
- BUG/MEDIUM: mux-fcgi: Use a safe loop to resume each stream eligible for sending
- MINOR: mux-fcgi: Use a dedicated function to resume streams eligible for sending
- CLEANUP: qpack: simplify length checks in qpack_decode_fs()
- MINOR: counters: Introduce COUNTERS_UPDATE_MAX()
- MINOR: listeners: Update the frequency counters separately when needed
- MINOR: proxies: Update beconn separately
- MINOR: stats: Add an option to disable the calculation of max counters
Add a new option, "stats calculate-max-counters [on|off]".
It makes it possible to disable the calculation of max counters, as they
can have a performance cost.
Update beconn separately from the call to COUNTERS_UPDATE_MAX(), as soon
there will be an option to get COUNTERS_UPDATE_MAX() to do nothing, and
we still want beconn to be properly updated, as it is used for other
purposes.
Update the frequency counters that are exported to the stats page
outside of the call to COUNTERS_UPDATE_MAX(), so that they will
happen even if COUNTERS_UPDATE_MAX() ends up doing nothing.
Introduce COUNTERS_UPDATE_MAX(), and use it instead of using
HA_ATOMIC_UPDATE_MAX() directly.
For now it just calls HA_ATOMIC_UPDATE_MAX(), but will later be modified
so that we can disable max calculation.
This can be backported up to 2.8 if the usage of COUNTERS_UPDATE_MAX()
generates too many conflicts.
This patch simplifies the decoding loop by merging the variable-length
integer truncation check (len == -1) with the subsequent buffer
availability check (len < length).
This removes redundant code blocks and improves readability without
changing the decoding logic.
Note that the second removal is correct, as the check was duplicate and
unnecessary."
At the end of fcgi_send(), if the connection is not full anymore, we loop on
the send list to resume FCGI stream for sending. But a streams may be
removed from the this list during the loop. So a safe loop must be used.
This patch should be backported to all stable versions.
Names found in DNS responses are lowered to be compared. A name is composed
of several labels, strings precedeed by their length on one byte. For
instance:
3www7haproxy3org
There is an bug when labels are lowered. The label length is not skipped and
tolower() function is called on it. So for label length in the range [65-90]
(uppercase char), 32 is added to the label length due to the conversion of a
uppercase char to lowercase. This bugs can lead to OOB read later in the
resolvers code.
The fix is quite obvious, the label length must be skipped when the label is
lowered.
Thank you to Kamil Frankowicz for having reported this.
This patch must be backported to all stable versions.
In functions used to decode a FCGI parameter, the test on the data length
before reading the parameter's name and value did not consider the offset
value used to skip already parsed data. So it was possible to read more data
than available (OOB read). To do so, a malicious FCGI server must send a
forged GET_VALUES_RESULT record containing a parameter with wrong name/value
length.
Thank you to Kamil Frankowicz for having reported this.
This patch must be backported to all stable versions.
There was an issue in the if/else statement in smp_fetch_bytes() function.
When req.bytes_in or req.bytes_out was requested, res.bytes_in was always
returned. It is now fixed.
This patch must be backported to 3.3.
This function is no longer used. So it is not really an bug. But it is still
available and could be used by legacy applets. In that case, we must take
care to increment the stconn bytes_in value accordingly when input data are
inserted.
This patch must be backported to 3.3.
In custom log format part, %[req.bytes_in] was erroneously documented as the
alias of %B. The good alias is %[res.bytes_in]. It is now fixed.
This patch must be backported to 3.3.
Since the 3.1, when stream's info are dump, it is possible to print the
yielding filter on each channel, if any. It was useful to detect buggy
filter on spinning loop. But it is not possible to detect a filter consuming
too much CPU per-execution. We can see a filter was executing in the
backtrace reported by the watchdog, but we are unable to spot the specific
one.
Thanks to this patch, it is now possible. When a dump is emitted, the
running or yield filters on each channel are now displayed with their
current state (RUNNING or YIELDING).
This patch could be backported as far as 3.2 because it could be useful to
spot issues. But the filter API was slightly refactored in 3.4, so this
patch should be adapted.
On the stream, the last_entity should reference the last rule or the last
filter evaluated during the stream processing. However, this info was not
saved when a filter failed on strem_start callback function. It is now
fixed.
This patch could be backported as far as 3.1.
When the filters API was refactored to improve loops on filters, some places
were not updated (or not fully updated). Some loops were not relying on
resume_filter_list_break() while it was possible. So let's do so with this
patch.
Since the 2.5, when stream's info are dump, it is possible to print the
yielding rule, if any. It was useful to detect buggy rules on spinning
loop. But it is not possible to detect a rule consuming too much CPU
per-execution. We can see a rule was executing in the backtrace reported by
the watchdog, but we are unable to spot the specific rule.
Thanks to this patch, it is now possible. When a dump is emitted, the
running or yield rule is now displayed with its current state (RUNNING or
YIELDING).
This patch could be backported as far as 3.2 because it could be useful to
spot issues.
When the response is send by HAProxy, from a applet or for the analyzers,
The request version is used for the response. The main reason is that there
is not real version for the response when this happens. "HTTP/1.1" is used,
but it is in fact just an HTX response. So the version of the request is
used.
In the same manner, when the request is sent from an applet (httpclient),
the response version is used, once available.
The purpose of this change is to return the most accurate version from the
user point of view.
Thanks to previous patches, we can now rely on the version stored in the
http_msg structure to get the request or the response version.
"req.ver" and "res.ver" sample fetch functions returns the string
representation of the version, without the prefix, so "<major>.<minor>", but
only if the version is valid. For the response, "res.ver" may be added from
a health-check context, in that case, the HTX message is used.
"capture.req.ver" and "capture.res.ver" does the same but the "HTTP/" prefix
is added to the result. And "capture.res.ver" cannot be called from a
health-check.
To ease the version formatting and avoid code duplication, an helper
function was added. So these samples are now relying on "get_msg_version()".
When the request or the response is received, the numerical value of the
message version is now saved. To do so, the field "vsn" was added in the
http_msg structure. It is an unsigned char. The 4 MSB bits are used for the
major digit and the 4 LSB bits for the minor one.
Of couse, the version must be valid. the HTX_SL_F_NOT_HTTP flag of the
start-line is used to be sure the version is valid. But because this flag is
quite new, we also take care the string representation of the version is 8
bytes length. 0 means the version is not valid.
When the response is parsed, we test the version to be sure it is
valid. However, the protocol was not tested. Now we take care that the
response version starts by "HTTP/", otherwise an error is returned.
Of course, it is still possible to by-pass this test with
"accept-unsafe-violations-in-http-response" option.
This patch could be backported to all stable versions.
Now, when the HTTP version format is not strictly valid, flags are set on
the h1 parser and the HTX start-line. H1_MF_NOT_HTTP is set on the H1 parser
and HTX_SL_F_NOT_HTTP is set on the HTX start-line. These flags were
introduced to avoid parsing again and again the version to know if it is a
valid version or not, escpecially because it is most of time valid.
htx_sl_vsn() function can now be used to retrieve the ist string
representing the HTTP version from a start-line passed as parameter. This
function takes care to return the right part of the start-line, depending on
its type (request or response).
From a lua TCP applet, in functions used to retrieve data (receive,
try_receive and getline), we must take care to disable receives when data
are returned (or on failure) and to restart receives when these functions
are called again. In addition, when an applet execution is finished, we must
restart receives to properly drain the request.
This patch should be backported to 3.3. On older version, no bug was
reported so we can wait a report first.
When the lua HTTP applet was refactored to use its own buffers, a bug was
introduced in receive() and getline() function. We rely on HTX_FL_EOM flag
to detect the end of the request. But there is nothing preventing extra
calls to these function, when the whole request was consumed. If this
happens, the call will yield waiting for more data with no way to stop it.
To fix the issue, APPLET_REQ_RECV flag was added to know the whole request
was received.
This patch should fix#3293. It must be backported to 3.3.
From a lua HTTP applet, in the getline() function, we must take care to
disable receives when a line is retrieved and to restart receives when the
function is called again. In addition, when an applet execution is finished,
we must restart receives to properly drain the request.
This patch could help to fix#3293. It must be backported to 3.3. On older
version, no bug was reported so we can wait a report first. But in that
case, hlua_applet_http_recv() should also be fixed (on 3.3 it was fixed
during the applets refactoring).
Same fix as this one for hpack:
7315428615 ("BUG/MEDIUM: hpack: correctly deal with too large decoded numbers")
Indeed, the encoding of integers for QPACK is the same as for HPACK but for 64 bits
integers.
Must be backported as far as 2.6.
This bug impacts only the QUIC backend. A QUIC server does receive
a server preferred address transport parameter.
In quic_transport_param_dec_pref_addr(), the boundary check for the
connection ID was inverted and incorrect. This could lead to an
out-of-bounds read during the following memcpy.
This patch fixes the comparison to ensure the buffer has enough input data
for both the CID and the mandatory Stateless Reset Token.
Thank you to Kamil Frankowicz for having reported this.
Must be backported to 3.3.
In qpack_decode_fs_pfx(), if the first qpack_get_varint() call
consumes the entire buffer, the code would perform a 1-byte
out-of-bounds read when accessing the sign bit via **raw.
This patch adds an explicit length check at the beginning of
qpack_get_varint(), which systematically secures all other callers
against empty inputs. It also adds a necessary check before the
second varint call in qpack_decode_fs_pfx() to ensure data is still
available before dereferencing the pointer to extract the sign bit,
returning QPACK_RET_TRUNCATED if the buffer is exhausted.
Thank you to Kamil Frankowicz for having reported this.
Must be backported as far as 2.6.
A call to huffman decoder function (huff_dec()) is made from qpack_decode_fs()
without checking the buffer length passed to this function, leading to OOB read
which can crash the process.
Thank you to Kamil Frankowicz for having reported this.
Must be backport as far as 2.6.
The varint hpack decoder supports unbounded numbers but returns 32-bit
results. This means that possible truncation my happen on some field
lengths or indexes that would be emitted as quantities that do not fit
in a 32-bit number. The final value will also depend on how the left
shift operation behaves on the target architecture (e.g. whether bits
are lost or used modulo 31). This could lead to a desynchronization of
the HPACK stream decoding compared to what an external observer would
see (e.g. from a network traffic capture). However, there isn't any
impact between streams, HPACK is performed at the connection level,
not at the stream level, so no stream may try to leverage this
limitation to have any effect on another one.
For the fix, instead of adding checks everywhere in the loop and for
the final stage, let's rewrite the decoder to compare the read value
to a max value that is shifted by 7 bits for every 7 bits read. This
allows a sender to continue to emit zeroes for higher bits without
being blocked, while detecting that a received value would overflow.
The loop is now simpler as it deals both with values with the higher
bit set and the final ones, and stops once the final value was recorded.
A test on non-zero before performing the shift was added to please
ubsan, though in practice zero shifted by any quantity remains zero.
But the test is cheap so that's OK.
Thanks to Guillaume Meunier, Head of Vulnerability Operations Center
France at Orange Cyberdefense, for reporting this bug.
This should be backported to all stable versions.
On the backend side, QUIC MUX may be started preemptively before the
ALPN negotiation. This is useful notably for 0-RTT implementation.
However, this was a source of crashes. ALPN was expected to be retrieved
from the server cache, however QUIC MUX still used the ALPN from the
transport layer. This could cause a crash, especially when several
connections runs in parallel as the server cache is shared among
threads.
Thanks to the previous patch which reworks QUIC MUX init, this solution
can now be fixed. Indeed, if conn_get_alpn() is not successful, MUX can
look at the server cache again to use the expected value.
Note that this could still prevent the MUX to work as expected if the
server cache is resetted between connect_server() and MUX init. Thus,
the ultimate solution would be to copy the cached ALPN into the
connection. This problem is not specific to QUIC though, and must be
fixed in a separate patch.
This patch reworks the installation of app-ops layer by QUIC MUX.
Previously, app_ops field was stored directly into the quic_conn
structure. Then the MUX reused it directly during its qmux_init().
This patch removes app_ops field from quic_conn and replaces it with a
copy of the negotiated ALPN. By using quic_alpn_to_app_ops(), it ensures
it remains compatible with a known application layer.
On the MUX layer, qcc_install_app_ops() now uses the standard
conn_get_alpn() to retrieve the ALPN from the transport layer. This is
done via the newly defined <get_alpn> QUIC xprt callback.
This new architecture should be cleaner as it better highlights the
responsibility of each layers in the ALPN/app negotiation.
Extract the conversion from ALPN to qcc_app_ops type from quic_conn
source file into QUIC MUX. The newly created function is named
quic_alpn_to_app_ops(). This will serve as a central point to identify
which ALPNs are currently supported in our QUIC stack.
This patch is purely a small refactoring. It will be useful for the next
one which rework MUX app-ops layer init. The current cleanup allows
notably to remove H3/hq-interop headers from quic_conn source file.
The QUIC MUX layer is closed after its transport counterpart. This may
be necessary then to reject any new streams opened by the remote peer.
This operation is dependent however from the application protocol.
Previously, a function qc_h3_request_reject() was directly implemented
in quic_conn source file for use when HTTP/3 was previously negotiated.
However, this solution was not evolutive and broke layering.
This patch introduces a new proper separation with a <strm_reject>
callback defined in quic_conn structure. When set, it will be used to
preemptively close any new stream. QUIC MUX is responsible to set it
just before its closure.
No functional change. This patch is purely a refactoring with a better
architecture design. Especially, H3 specific code from transport layer
is now completely removed.
In most of haproxy code, ALPN is used as a signed char pointer. In QUIC
code instead, it is manipulated as unsigned.
Unifies this by using signed type in QUIC code. This allows to remove a
bunch of unnecessary casts.
The conversion of TASK_WOKEN_RES to a stream event was missing. Among other
things, this wakeup reason is used when a stream is dequeued. So it was
possible to skip the connection establishment if the stream was also woken
up for a timer reason. When this happened, the stream was blocked till the
queue timeout expiration.
Converting TASK_WOKEN_RES to STRM_EVT_RES fixes the issue.
This patch should fix the issue #3290. It must be backported as far as 3.2.
hlua_check_proxy() may now return NULL if the target proxy instance has
been flagged for deletion. Thus, proxies method have been adjusted and
may push nil to report such case.
This patch fixes these error paths. When nil is pushed, 1 must be
returned instead of 0. This represents the count of pushed values on the
stack which can be retrieved by the caller.
No need to backport.
Complete delete backend regtests by checking deletion of a proxy with a
reference on an unnamed defaults instance. This operation is sensible as
the defaults refcount is decremented, and when the last backend is
removed, the defaults is also freed.
Add a reg-tests to test "del backend" CLI command. First, checks are
performed to ensure a backend cannot be deleted if not in the expected
state.
Then, a "del backend" success is tested. Stats are dumped to ensure the
backend instance is indeed removed.
This patch finalizes "del backend" handler by implementing the proper
proxy deletion.
After ensuring backend deletion can be performed, several steps are
executed. First, any watcher elements are updated to point on the next
proxy instance. The backend is then removed from ID and name global
trees and is finally detached from proxies_list.
Once the backend instance is removed from proxies_list, the backend
cannot be found by new elements. Thread isolation is lifted and
proxy_drop() is called, which will purge the proxy if its refcount is
null. Thanks to recently introduced PROXIES_DEL_LOCK, proxy_drop() is
thread safe.
Default proxy refcount <def_ref> is used to comptabilize reference on a
default proxy instance by standard proxies. Currently, this is necessary
when a default proxy defines TCP/HTTP rules or a tcpcheck ruleset.
Transform every access on <def_ref> so that atomic operations are now
used. Currently, this is not strictly needed as default proxies
references are only manipulated at init or deinit in single thread mode.
However, when dynamic backends deletion will be implemented, <def_ref>
will be decremented at runtime also.
This patch is similar to the previous one, but this time it deals with
functions related to defaults proxies instances. Lock PROXIES_DEL_LOCK
is used to protect accesses on global collections.
This patch will be necessary to implement dynamic backend deletion, even
if defaults won't be use as direct target of a "del backend" CLI.
However, a backend may have a reference on a default instance. When the
backend is freed, this references is released, which can in turn cause
the freeing of the default proxy instance. All of this will occur at
runtime, outside of thread isolation.
Define a new lock with label PROXIES_DEL_LOCK. Its purpose is to protect
operations performed on global lists or trees while a proxy is freed.
Currently, this lock is unneeded as proxies are only freed on
single-thread init or deinit. However, with the incoming dynamic backend
deletion, this operation will be also performed at runtime, outside of
thread isolation.
Implement be-removable argument to CLI wait. This is implemented via
be_check_for_deletion() invokation, also used by "del backend" handler.
The objective is to test whether a backend instance can be removed. If
this is not the case, the command may returns immediately if the target
proxy is incompatible with dynamic removal or if a user action is
required. Else, the command will wait until the temporary restriction is
lifted.
Currenly, quic_conn on the backend side may access their parent proxy
instance during their lifetime. In particular, this is the case for
counters update, with <prx_counters> field directly referencing a proxy
memory zone.
As such, this prevents safe backend removal. One solution would be to
check if the upper connection instance is still alive, as a proxy cannot
be removed if connection are still active. However, this would
completely prevent proxy counters update via
quic_conn_prx_cntrs_update(), as this is performed on quic_conn release.
Another solution would be to use refcount, or a dedicated counter on the
which account for QUIC connections on a backend instance. However,
refcount is currently only used by short-term references, and it could
also have a negative impact on performance.
Thus, the simplest solution for now is to disable a backend removal if a
QUIC server is/was used in it. This is considered acceptable for now as
QUIC on the backend side is experimental.
Ensure a backend instance cannot be removed if there is still server in
it. This is checked via be_check_for_deletion() to ensure "del backend"
cannot be executed. The only solution is to use "del server" to remove
on the servers instances.
This check only covers servers not yet targetted via "del server". For
deleted servers not yet purged (due to their refcount), the proxy
refcount is incremented but this does not block "del backend"
invokation.
Define a new proxy flag PR_FL_NON_PURGEABLE. This is used to mark every
proxy instance explicitely referenced in the config. Such instances
cannot be deleted at runtime.
Static use_backend/default_backend rules are handled in
proxy_finalize(). Also, sample expression proxy references are protected
via smp_resolve_args().
Note that this last case also incidentally protects any proxies
referenced via a CLI "set var" expression. This should not be the case
as in this case variable value is instantly resolved so the proxy
reference is not needed anymore. This also affects dynamic servers.
