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Better sanitize metrics labels #41

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76743c0
Sanitize metrics labels to remove newlines and quotes and limit length
weaversam8 Nov 18, 2025
1d4c47f
Fix a few tests that weren't returning their generators correctly
weaversam8 Nov 18, 2025
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37 changes: 34 additions & 3 deletions src/openmetrics.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@
-export([init/2, terminate/3]).
-export([get/1]).

-define(AllowedLabelChars, "[^a-zA-Z0-9:_+.]").

% cowboy functions:
init(Req, State) ->
{ok, Req1} = ?MODULE:get(Req),
Expand Down Expand Up @@ -87,8 +89,37 @@ get_exemplar_string(Name, Tags) ->
""
end.

% Truncate label to max length from application env (default 1024)
truncate_label(Value) when is_list(Value) ->
MaxLen = application:get_env(imetrics, max_label_length, 1024),
case length(Value) > MaxLen of
true -> lists:sublist(Value, MaxLen);
false -> Value
end;
truncate_label(Value) when is_binary(Value) ->
MaxLen = application:get_env(imetrics, max_label_length, 1024),
case byte_size(Value) > MaxLen of
true -> binary:part(Value, 0, MaxLen);
false -> Value
end.

% Sanitize and truncate label names and values by replacing any character not in [a-zA-Z0-9:_+.] with underscores
% Version for when we need a list result (no extra conversions in create_label_string)
sanitize_label_to_list(Value) when is_list(Value) ->
Sanitized = re:replace(Value, ?AllowedLabelChars, "_", [global, {return, list}]),
truncate_label(Sanitized);
sanitize_label_to_list(Value) ->
sanitize_label_to_list(binary:bin_to_list(imetrics_utils:bin(Value))).

% Version for when we need a binary result (no extra conversions in create_tag_string)
sanitize_label_to_binary(Value) when is_binary(Value) ->
Sanitized = re:replace(Value, ?AllowedLabelChars, "_", [global, {return, binary}]),
truncate_label(Sanitized);
sanitize_label_to_binary(Value) ->
sanitize_label_to_binary(imetrics_utils:bin(Value)).

create_label_string(Labels) ->
Result = maps:fold(fun(Label, Value, Acc) -> ("," ++ binary:bin_to_list(imetrics_utils:bin(Label)) ++ "=\"" ++ binary:bin_to_list(Value) ++ "\"" ++ Acc) end, "", Labels),
Result = maps:fold(fun(Label, Value, Acc) -> ("," ++ sanitize_label_to_list(Label) ++ "=\"" ++ sanitize_label_to_list(Value) ++ "\"" ++ Acc) end, "", Labels),
case length(Result) of
R when R < 3 ->
Result;
Expand Down Expand Up @@ -121,7 +152,7 @@ deliver_legacy_mapped_metric(Req, Name, [{Key, Value} | Tail]) ->
deliver_legacy_mapped_metric(Req, Name, Tail);
_ ->
cowboy_req:stream_body(
[<<Name/binary, "{">>, <<"map_key">>, "=\"", Key, "\"} ", strnum(Value), "\n"], nofin, Req
[<<Name/binary, "{">>, <<"map_key">>, "=\"", sanitize_label_to_binary(Key), "\"} ", strnum(Value), "\n"], nofin, Req
),
deliver_legacy_mapped_metric(Req, Name, Tail)
end;
Expand All @@ -148,7 +179,7 @@ deliver_mapped_metric(_Req, _Type, _Name, []) ->
create_tag_string(Tags) ->
TagPairs = lists:foldl(
fun({TagName, TagValue}, Acc) ->
[[list_to_binary(atom_to_list(TagName)), "=\"", TagValue, "\""] | Acc]
[[sanitize_label_to_binary(TagName), "=\"", sanitize_label_to_binary(TagValue), "\""] | Acc]
end,
[],
maps:to_list(Tags)
Expand Down
80 changes: 52 additions & 28 deletions test/imetrics_tests.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -130,16 +130,7 @@ exemplar_test_() ->
fun exemplar_test/1}.

exemplar_test(_Fixture) ->
?_assertEqual(true, imetrics:set_exemplar(a, 1)),
?_assertEqual(true, imetrics:set_exemplar(b, #{c => 1}, 2)),
?_assertEqual(true, imetrics:set_exemplar(c, 2, #{d => 2, e => "aa"})),
?_assertEqual(true, imetrics:set_exemplar(f, 3, 946684800)),
?_assertEqual(true, imetrics:set_exemplar(g, #{h => 1, i=> 2}, 3, #{j => k})),
?_assertEqual(true, imetrics:set_exemplar(g, #{h => 2}, 4, 978307200)),
?_assertEqual(true, imetrics:set_exemplar(i, 5, #{j => "bb"}, 1009843200)),
?_assertEqual(true, imetrics:set_exemplar(k, #{l => 3}, 6, #{m => "cc"}, 1577836800)),


% Setup code first
imetrics:set_exemplar(a, 1),
imetrics:set_exemplar(b, #{c => 1}, 2),
imetrics:set_exemplar(c, 2, #{d => 2, e => "aa"}),
Expand All @@ -151,25 +142,35 @@ exemplar_test(_Fixture) ->
imetrics:set_exemplar(l, #{name => "test1"}, 1),
imetrics:set_exemplar(l, #{name => "test2"}, 2),

?_assertMatch({1, #{}, _}, imetrics:get_exemplar(#{'__name__' => <<"a">>})),
?_assertMatch({2, #{}, _}, imetrics:get_exemplar(#{'__name__' => <<"b">>, c => <<"1">>})),
% Test variable definitions
Test3Map = #{d => <<"2">>, e => <<"aa">>},
?_assertMatch({2, Test3Map, _}, imetrics:get_exemplar(#{'__name__' => <<"c">>})),
?_assertMatch({3, #{}, 946684800}, imetrics:get_exemplar(#{'__name__' => <<"f">>})),
Test5Map = #{j => <<"k">>},
?_assertMatch({3, Test5Map, _}, imetrics:get_exemplar(#{'__name__' => <<"g">>, h => <<"1">>, i => <<"2">>})),
?_assertMatch({4, #{}, 978307200}, imetrics:get_exemplar(#{'__name__' => <<"g">>, h => <<"2">>})),
Test7Map = #{j => <<"bb">>},
?_assertMatch({5, Test7Map, 1009843200}, imetrics:get_exemplar(#{'__name__' => <<"i">>})),
Test8Map = #{m => <<"cc">>},
?_assertMatch({6, Test8Map, 1577836800}, imetrics:get_exemplar(#{'__name__' => <<"k">>, l => <<"3">>})),

?_assertEqual(true, imetrics:set_exemplar(k, #{l => 3}, 0.1, 1893456000)),
imetrics:set_exemplar(k, #{l => 3}, 0.1, 1893456000),
?_assertMatch({0.1, #{}, 1893456000}, imetrics:get_exemplar(#{'__name__' => <<"k">>, l => <<"3">>})),

?_assertMatch({1, #{}, _}, imetrics:get_exemplar(#{name => <<"test1">>, '__name__' => <<"l">>})),
?_assertMatch({2, #{}, _}, imetrics:get_exemplar(#{name => <<"test2">>, '__name__' => <<"l">>})).
% Return list of test assertions
[
?_assertEqual(true, imetrics:set_exemplar(a, 1)),
?_assertEqual(true, imetrics:set_exemplar(b, #{c => 1}, 2)),
?_assertEqual(true, imetrics:set_exemplar(c, 2, #{d => 2, e => "aa"})),
?_assertEqual(true, imetrics:set_exemplar(f, 3, 946684800)),
?_assertEqual(true, imetrics:set_exemplar(g, #{h => 1, i=> 2}, 3, #{j => k})),
?_assertEqual(true, imetrics:set_exemplar(g, #{h => 2}, 4, 978307200)),
?_assertEqual(true, imetrics:set_exemplar(i, 5, #{j => "bb"}, 1009843200)),
?_assertEqual(true, imetrics:set_exemplar(k, #{l => 3}, 6, #{m => "cc"}, 1577836800)),
?_assertMatch({1, #{}, _}, imetrics:get_exemplar(#{'__name__' => <<"a">>})),
?_assertMatch({2, #{}, _}, imetrics:get_exemplar(#{'__name__' => <<"b">>, c => <<"1">>})),
?_assertMatch({2, Test3Map, _}, imetrics:get_exemplar(#{'__name__' => <<"c">>})),
?_assertMatch({3, #{}, 946684800}, imetrics:get_exemplar(#{'__name__' => <<"f">>})),
?_assertMatch({3, Test5Map, _}, imetrics:get_exemplar(#{'__name__' => <<"g">>, h => <<"1">>, i => <<"2">>})),
?_assertMatch({4, #{}, 978307200}, imetrics:get_exemplar(#{'__name__' => <<"g">>, h => <<"2">>})),
?_assertMatch({5, Test7Map, 1009843200}, imetrics:get_exemplar(#{'__name__' => <<"i">>})),
?_assertMatch({6, Test8Map, 1577836800}, imetrics:get_exemplar(#{'__name__' => <<"k">>, l => <<"3">>})),
?_assertEqual(true, imetrics:set_exemplar(k, #{l => 3}, 0.1, 1893456000)),
?_assertMatch({0.1, #{}, 1893456000}, imetrics:get_exemplar(#{'__name__' => <<"k">>, l => <<"3">>})),
?_assertMatch({1, #{}, _}, imetrics:get_exemplar(#{name => <<"test1">>, '__name__' => <<"l">>})),
?_assertMatch({2, #{}, _}, imetrics:get_exemplar(#{name => <<"test2">>, '__name__' => <<"l">>}))
].

init_counter_test_() ->
{setup,
Expand All @@ -178,14 +179,19 @@ init_counter_test_() ->
fun init_counter_test/1}.

init_counter_test(_Fixture) ->
% Setup and get initial data
Data1 = imetrics:get_with_types(),
?_assertEqual(undefined, proplists:get_value(<<"empty_counter">>, Data1)),
?_assertEqual(undefined, proplists:get_value(<<"empty_counter_mapped">>, Data1)),
imetrics:init_counter(empty_counter),
imetrics:init_counter(empty_counter_mapped, #{key => "abc"}),
Data2 = imetrics:get_with_types(),
?_assertEqual({counter, [{#{}, 0}]}, proplists:get_value(<<"empty_counter">>, Data2)),
?_assertEqual({counter, [{#{key => <<"abc">>}, 0}]}, proplists:get_value(<<"empty_counter_mapped">>, Data2)).

% Return list of test assertions
[
?_assertEqual(undefined, proplists:get_value(<<"empty_counter">>, Data1)),
?_assertEqual(undefined, proplists:get_value(<<"empty_counter_mapped">>, Data1)),
?_assertEqual({counter, [{#{}, 0}]}, proplists:get_value(<<"empty_counter">>, Data2)),
?_assertEqual({counter, [{#{key => <<"abc">>}, 0}]}, proplists:get_value(<<"empty_counter_mapped">>, Data2))
].

%% get tests
get_test_() ->
Expand Down Expand Up @@ -226,6 +232,12 @@ start_get() ->
imetrics:add(counter4_invalid_exemplar),
imetrics:set_exemplar(counter4_invalid_exemplar, 3, #{valid_label => "Invalid \"Value\""}, 12623040000),

imetrics:add(newline_counter, #{test_label => "value\nwith\"double\"\nquotes"}),

% Test label truncation - create a label longer than default 1024 chars
LongLabel = lists:duplicate(1050, $a), % 1050 'a' characters
imetrics:add(long_label_counter, #{long_label => LongLabel}),

imetrics_hist_openmetrics:new(hist, [0,0.01,0.1,0.5,1,5,10]),
imetrics_hist_openmetrics:new(tagged_hist, #{hist_tag => "one"}, [0,1], 5),
imetrics_hist_openmetrics:new(tagged_hist, #{hist_tag => "two"}, [0,10], 21),
Expand Down Expand Up @@ -351,8 +363,12 @@ http_test_openmetrics(#{port := Port}) ->
"counter_tuple{} 1",
"# TYPE imetrics_metric_fun_timeout counter",
"imetrics_metric_fun_timeout{metric=\"fn_gauge_timeout\"} 1",
"# TYPE long_label_counter counter",
"long_label_counter{long_label=\"" ++ lists:duplicate(1024, $a) ++ "\"} 1",
"# TYPE mapped_counter counter",
"mapped_counter{map_key=\"key\"} 1",
"# TYPE newline_counter counter",
"newline_counter{test_label=\"value_with_double__quotes\"} 1",
"# TYPE tagged_counter counter",
"tagged_counter{tag1=\"val1\"} 1",
"# TYPE tagged_counter2 counter",
Expand Down Expand Up @@ -460,8 +476,12 @@ http_test_openmetrics_strict(#{port := Port}) ->
"counter_tuple{} 1",
"# TYPE imetrics_metric_fun_timeout counter",
"imetrics_metric_fun_timeout{metric=\"fn_gauge_timeout\"} 3",
"# TYPE long_label_counter counter",
"long_label_counter{long_label=\"" ++ lists:duplicate(1024, $a) ++ "\"} 1",
"# TYPE mapped_counter counter",
"mapped_counter{map_key=\"key\"} 1",
"# TYPE newline_counter counter",
"newline_counter{test_label=\"value_with_double__quotes\"} 1",
"# TYPE tagged_counter counter",
"tagged_counter{tag1=\"val1\"} 1",
"# TYPE tagged_counter2 counter",
Expand Down Expand Up @@ -549,8 +569,12 @@ http_test_openmetrics_exemplars(#{port := Port}) ->
"counter_tuple_total{} 1",
"# TYPE imetrics_metric_fun_timeout counter",
"imetrics_metric_fun_timeout_total{metric=\"fn_gauge_timeout\"} 4",
"# TYPE long_label_counter counter",
"long_label_counter_total{long_label=\"" ++ lists:duplicate(1024, $a) ++ "\"} 1",
"# TYPE mapped_counter counter",
"mapped_counter_total{map_key=\"key\"} 1",
"# TYPE newline_counter counter",
"newline_counter_total{test_label=\"value_with_double__quotes\"} 1",
"# TYPE tagged_counter counter",
"tagged_counter_total{tag1=\"val1\"} 1",
"# TYPE tagged_counter2 counter",
Expand Down