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Willy Tarreau 44c5ff69ac MEDIUM: vars: make the var() sample fetch function really return type ANY
A long-standing issue was reported in issue #1215.

In short, var() was initially internally declared as returning a string
because it was not possible by then to return "any type". As such, users
regularly get trapped thinking that when they're storing an integer there,
then the integer matching method automatically applies. Except that this
is not possible since this is related to the config parser and is decided
at boot time where the variable's type is not known yet.

As such, what is done is that the output being declared as type string,
the string match will automatically apply, and any value will first be
converted to a string. This results in several issues like:

    http-request set-var(txn.foo) int(-1)
    http-request deny if { var(txn.foo) lt 0 }

not working. This is because the string match on the second line will in
fact compare the string representation of the variable against strings
"lt" and "0", none of which matches.

The doc says that the matching method is mandatory, though that's not
the case in the code due to that default string type being permissive.
There's not even a warning when no explicit match is placed, because
this happens very deep in the expression evaluator and making a special
case just for "var" can reveal very complicated.

The set-var() converter already mandates a matching method, as the
following will be rejected:

    ... if { int(12),set-var(txn.truc) 12 }

  while this one will work:

    ... if { int(12),set-var(txn.truc) -m int 12 }

As such, this patch this modifies var() to match the doc, returning the
type "any", and mandating the matching method, implying that this bogus
config which does not work:

    http-request set-var(txn.foo) int(-1)
    http-request deny if { var(txn.foo) lt 0 }

  will need to be written like this:

    http-request set-var(txn.foo) int(-1)
    http-request deny if { var(txn.foo) -m int lt 0 }

This *will* break some configs (and even 3 of our regtests relied on
this), but except those which already match string exclusively, all
other ones are already broken and silently fail (and one of the 3
regtests, the one on FIX, was bogus regarding this).

In order to fix existing configs, one can simply append "-m str"
after a "var()" in an ACL or "if" expression:

    http-request deny unless { var(txn.jwt_alg) "ES" }

  must become:

    http-request deny unless { var(txn.jwt_alg) -m str "ES" }

Most commonly, patterns such as "le", "lt", "ge", "gt", "eq", "ne" in
front of a number indicate that the intent was to match an integer,
and in this case "-m int" would be desired:

    tcp-response content reject if ! { var(res.size) gt 3800 }

  ought to become:

    tcp-response content reject if ! { var(res.size) -m int gt 3800 }

This must not be backported, but if a solution is found to at least
detect this exact condition in the generic expression parser and
emit a warning, this could probably help spot configuration bugs.

Link: https://www.mail-archive.com/haproxy@formilux.org/msg41341.html
Cc: Christopher Faulet <cfaulet@haproxy.com>
Cc: Tim Düsterhus <tim@bastelstu.be>
2021-11-02 17:28:43 +01:00
.github CI: Clean up formatting in GitHub Action definitions 2021-10-18 07:17:04 +02:00
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include BUILD/MINOR: cpuset freebsd build fix 2021-11-02 13:58:28 +01:00
reg-tests MEDIUM: vars: make the var() sample fetch function really return type ANY 2021-11-02 17:28:43 +01:00
scripts BUILD: adopt script/build-ssl.sh for OpenSSL-3.0.0beta2 2021-08-25 05:16:00 +02:00
src MEDIUM: vars: make the var() sample fetch function really return type ANY 2021-11-02 17:28:43 +01:00
tests CLEANUP: assorted typo fixes in the code and comments 2021-08-16 12:37:59 +02:00
.cirrus.yml CI: introduce scripts/build-vtest.sh for installing VTest 2021-05-18 10:48:30 +02:00
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BRANCHES DOC: fix some spelling issues over multiple files 2021-01-08 14:53:47 +01:00
CHANGELOG [RELEASE] Released version 2.5-dev11 2021-10-22 19:40:44 +02:00
CONTRIBUTING CLEANUP: assorted typo fixes in the code and comments 2021-08-16 12:37:59 +02:00
INSTALL CLEANUP: assorted typo fixes in the code and comments 2021-08-16 12:37:59 +02:00
LICENSE LICENSE: add licence exception for OpenSSL 2012-09-07 13:52:26 +02:00
MAINTAINERS CONTRIB: move spoa_example out of the tree 2021-04-21 09:39:06 +02:00
Makefile MINOR: jwt: Parse JWT alg field 2021-10-14 16:38:08 +02:00
README DOC: create a BRANCHES file to explain the life cycle 2019-06-15 22:00:14 +02:00
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SUBVERS BUILD: use format tags in VERDATE and SUBVERS files 2013-12-10 11:22:49 +01:00
VERDATE [RELEASE] Released version 2.5-dev11 2021-10-22 19:40:44 +02:00
VERSION [RELEASE] Released version 2.5-dev11 2021-10-22 19:40:44 +02:00

The HAProxy documentation has been split into a number of different files for
ease of use.

Please refer to the following files depending on what you're looking for :

  - INSTALL for instructions on how to build and install HAProxy
  - BRANCHES to understand the project's life cycle and what version to use
  - LICENSE for the project's license
  - CONTRIBUTING for the process to follow to submit contributions

The more detailed documentation is located into the doc/ directory :

  - doc/intro.txt for a quick introduction on HAProxy
  - doc/configuration.txt for the configuration's reference manual
  - doc/lua.txt for the Lua's reference manual
  - doc/SPOE.txt for how to use the SPOE engine
  - doc/network-namespaces.txt for how to use network namespaces under Linux
  - doc/management.txt for the management guide
  - doc/regression-testing.txt for how to use the regression testing suite
  - doc/peers.txt for the peers protocol reference
  - doc/coding-style.txt for how to adopt HAProxy's coding style
  - doc/internals for developer-specific documentation (not all up to date)