Matches is a special case that looks on the RHS and tries
to convert every unparsed value to a string, regardless
of the LHS type. This is not how types work in the display
filter. Require double-quotes to avoid ambiguity, because
matches doesn't follow normal Wireshark display filter
type rules. It doesn't need nor benefit from the flexibility
provided by unparsed strings in the syntax.
For matches the RHS is always a literal strings except
if the RHS is also a field name, then it complains of an
incompatible type. This is confusing. No type can be compatible
because no type rules are ever considered. Every unparsed value is
a text string except if it happens to coincide with a field
name it also requires double-quoting or it throws a syntax error,
just to be difficult. We could remove this odd quirk but requiring
double-quotes for regular expressions is a better, more elegant
fix.
Before:
Filter: tcp matches "udp"
Constants:
00000 PUT_PCRE udp -> reg#1
Instructions:
00000 READ_TREE tcp -> reg#0
00001 IF-FALSE-GOTO 3
00002 ANY_MATCHES reg#0 matches reg#1
00003 RETURN
Filter: tcp matches udp
Constants:
00000 PUT_PCRE udp -> reg#1
Instructions:
00000 READ_TREE tcp -> reg#0
00001 IF-FALSE-GOTO 3
00002 ANY_MATCHES reg#0 matches reg#1
00003 RETURN
Filter: tcp matches udp.srcport
dftest: tcp and udp.srcport are not of compatible types.
Filter: tcp matches udp.srcportt
Constants:
00000 PUT_PCRE udp.srcportt -> reg#1
Instructions:
00000 READ_TREE tcp -> reg#0
00001 IF-FALSE-GOTO 3
00002 ANY_MATCHES reg#0 matches reg#1
00003 RETURN
After:
Filter: tcp matches "udp"
Constants:
00000 PUT_PCRE udp -> reg#1
Instructions:
00000 READ_TREE tcp -> reg#0
00001 IF-FALSE-GOTO 3
00002 ANY_MATCHES reg#0 matches reg#1
00003 RETURN
Filter: tcp matches udp
dftest: "udp" was unexpected in this context.
Filter: tcp matches udp.srcport
dftest: "udp.srcport" was unexpected in this context.
Filter: tcp matches udp.srcportt
dftest: "udp.srcportt" was unexpected in this context.
The error message could still be improved.
This includes as little as possible in the assertion header, so
that it can be included globally in every file without pulling
any unwanted definitions. In particular pulling stdlib.h is
avoided because that can have side effects if it wants to
include non-portable extensions.
It is possible to have side-effects from include glib.h too, for
example because of G_LOG_DOMAIN.
These side-effects are usually avoidable with careful ordering
of pre-processor directives but with multiple levels of indirections
it can be hard to track. Better to make it robust to these kinds
of failures in the first place.
Also integrate with our logger for a cohesive experience (but
keep it a private dependency).
Use a void expression instead of removing the expression
entirely. Under certain conditions, for example as the only
statement in an if() conditional, removing the assertion
will generate compiler warnings.
Currently our build generates very many warnings if
G_DISABLE_ASSERT is defined.
Add ws_assert() and ws_assert_not_reached() to incrementally
replace existing assertions and then disable them using
WS_DISABLE_ASSERT.
Assertions are disabled with CMake build type Release.
By default the build type is RelWithDebInfo so the current
behaviour of enabling assertions by default is (for now) preserved.
Add some notes to README.Developer.
João Valverde