path: root/capchild
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authorPeter Wu <peter@lekensteyn.nl>2016-09-18 16:19:58 +0200
committerAnders Broman <a.broman58@gmail.com>2016-09-23 05:59:26 +0000
commitb6a2915d0d5a7ab1524a49b216290f1e33feb19b (patch)
tree69af4ff8b19177276bbfcdfb138a5d6e326eeaaa /capchild
parent064f4d18dbc2cba6452d69bd354da2ff234b4182 (diff)
mate: fix Match edge cases, improve documentation
Use strcmp to sort AVPs in an AVPL and for matching instead of comparing pointer addresses. Pointers can only be used for (in)equality, there is no ordering in them. Matching of attributes however requires a better ordering to know whether the operator (condition) or whether the operand (data) can be skipped. Otherwise it is possible that condition (b) randomly fails to match data (a,b). User-visible changes (mainly edge cases): - Loose (a=1, a?) on data (a=0, a=1) would previously fail to return (a=0,a=1) because the a? condition is not tried for data a=0. Now it tries all compatible conditions for a data AVP. - Any Match condition like (a=1, a^1) would previously be treated the same as (a=1) while (a^1, a=1) would still be seen as (a^1, a=1). The first case is now fixed to match (a=1, a^1). (Via a fix in insert_avp to ensure that (a=1) is not considered the same as (a^1).) - Every (a=1, a=2) on data (a=1, b=1) previously failed, but the comment "it will not create a list if there is not a match for every attribute in op" suggests that it should return (a=1). - Every (a=1) on data (a=2) previously succeeded (bug) while it would fail on (a=2, b=1). This is fixed now by checking whether any of the conditions really have matching data for the attribute. Other changes: optimize merge_avpl and new_avpl_*_match to insert in linear time instead of quadratic, rewrite and add comments in an attempt to make it easier to understand. Merge the new_avpl_every_match and new_avpl_exact_match functions and rename it to new_avpl_pairs_match to reflects its actual implemented functionality. Not addressed in this patch is the quasi-randomness of the returned data AVPL. AVPLs are unordered, so the condition Strict (a?) on data (a=1, a=2) could in theory return either (a=1) or (a=2). In practice this returns (a=1) because of alphabetical ordering, but this cannot really be relied on. It gets worse for conditions like Strict (a?, a>1), these are considered undefined behavior (without warnings for now). Ping-Bug: 12184 Change-Id: I0008448ffcb96183f106cb937c4f488e26a82f92 Reviewed-on: https://code.wireshark.org/review/17777 Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com> Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org> Reviewed-by: Michael Mann <mmann78@netscape.net> Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com> Reviewed-by: Anders Broman <a.broman58@gmail.com>
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