bug fix: new ares_strsplit #492
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The test reveals a bug in the implementation of ares_strsplit when the
make_set parameter is set to 1, as distinct domains are confused for
equal:
out = ares_strsplit("example.com, example.co", ", ", 1, &n);
evaluates to n = 1 with out = { "example.com" }.
The purpose of ares_strsplit in c-ares is to split a comma-delimited
string of unique (up to letter case) domains. However, because the
terminating NUL byte was not checked in the substrings when comparing
for uniqueness, the function would sometimes drop domains it should
not. For example,
ares_strsplit("example.com, example.co", ",")
would only result in a single domain "example.com".
Aside from this bugfix, the following cleanup is performed:
1. The tokenization now happens with the help of strcspn instead of the
custom function is_delim.
2. The function list_contains has been inlined.
3. The interface of ares_strsplit has been simplified by removing the
parameter make_set since in practice it was always 1.
4. There are fewer passes over the input string.
5. We resize the table using realloc() down to its minimum size.
6. The docstring of ares_strsplit is updated and also a couple typos
are fixed.
There occurs a single use of ares_strsplit and since the make_set
parameter has been removed, the call in ares_init.c is modified
accordingly. The unit test for ares_strsplit is also updated.
bagder
approved these changes
Nov 8, 2022
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The first commit adds a unit test that reveals a bug in
ares_strsplitand the second commit fixes the algorithm.