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fix: handle empty proxy environment variables
When proxy environment variables (http_proxy, https_proxy, etc.) are set to empty strings or whitespace-only values, hackney would crash with a pattern match error in hackney_url:parse_netloc/2. This fix: - Checks for empty strings in do_get_proxy_env/1 - Strips whitespace from proxy URLs and treats whitespace-only as empty - Adds comprehensive unit tests to prevent regression - Exports proxy functions for testing when compiled with -DTEST Fixes the issue where export http_proxy="" would cause hackney requests to fail.
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‎src/hackney.erl‎

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -33,6 +33,10 @@
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pause_stream/1,
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resume_stream/1]).
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-ifdef(TEST).
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-export([get_proxy_env/1, do_get_proxy_env/1]).
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-endif.
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-define(METHOD_TPL(Method),
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-export([Method/1, Method/2, Method/3, Method/4])).
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-include("hackney_methods.hrl").
@@ -830,7 +834,14 @@ get_proxy_env(S) when S =:= http; S =:= http_unix ->
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do_get_proxy_env([Var | Rest]) ->
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case os:getenv(Var) of
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false -> do_get_proxy_env(Rest);
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Url -> {ok, Url}
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"" -> do_get_proxy_env(Rest);
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Url ->
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%% Trim all whitespace (spaces, tabs, newlines, etc.)
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TrimmedUrl = re:replace(Url, "^\\s+|\\s+$", "", [global, {return, list}]),
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case TrimmedUrl of
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"" -> do_get_proxy_env(Rest);
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_ -> {ok, TrimmedUrl}
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end
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end;
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do_get_proxy_env([]) ->
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false.

‎test/hackney_proxy_tests.erl‎

Lines changed: 138 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,138 @@
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%%% -*- erlang -*-
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%%%
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%%% This file is part of hackney released under the Apache 2 license.
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%%% See the NOTICE for more information.
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%%%
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%%% Copyright (c) 2025 Benoît Chesneau <[email protected]>
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%%%
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-module(hackney_proxy_tests).
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-include_lib("eunit/include/eunit.hrl").
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%% Test empty proxy environment variables handling
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empty_proxy_env_test_() ->
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{setup,
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fun setup/0,
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fun teardown/1,
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fun(State) ->
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[
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{"Empty http_proxy", fun() -> test_empty_proxy_env("http_proxy", State) end},
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{"Empty HTTP_PROXY", fun() -> test_empty_proxy_env("HTTP_PROXY", State) end},
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{"Empty https_proxy", fun() -> test_empty_proxy_env("https_proxy", State) end},
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{"Empty HTTPS_PROXY", fun() -> test_empty_proxy_env("HTTPS_PROXY", State) end},
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{"Whitespace http_proxy", fun() -> test_whitespace_proxy_env("http_proxy", State) end},
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{"Whitespace HTTPS_PROXY", fun() -> test_whitespace_proxy_env("HTTPS_PROXY", State) end},
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{"Multiple spaces proxy", fun() -> test_multiple_spaces_proxy_env("http_proxy", State) end},
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{"Valid proxy URL", fun() -> test_valid_proxy_env("http_proxy", State) end},
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{"Valid proxy with spaces", fun() -> test_valid_proxy_with_spaces("HTTP_PROXY", State) end}
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]
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end}.
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setup() ->
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%% Save current environment variables
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SavedEnv = [{Var, os:getenv(Var)} || Var <- ["http_proxy", "HTTP_PROXY",
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"https_proxy", "HTTPS_PROXY",
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"all_proxy", "ALL_PROXY"]],
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%% Clear all proxy environment variables
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[os:unsetenv(Var) || {Var, _} <- SavedEnv],
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%% Clear hackney's cached proxy settings
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application:unset_env(hackney, http_proxy),
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application:unset_env(hackney, https_proxy),
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SavedEnv.
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teardown(SavedEnv) ->
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%% Restore original environment variables
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lists:foreach(fun
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({Var, false}) -> os:unsetenv(Var);
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({Var, Value}) -> os:putenv(Var, Value)
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end, SavedEnv),
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%% Clear hackney's cached proxy settings
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application:unset_env(hackney, http_proxy),
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application:unset_env(hackney, https_proxy).
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test_empty_proxy_env(Var, _State) ->
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os:putenv(Var, ""),
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%% Clear cached values first
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application:unset_env(hackney, http_proxy),
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application:unset_env(hackney, https_proxy),
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%% This should not crash and should return false (no proxy)
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Result = hackney:get_proxy_env(http),
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?assertEqual(false, Result),
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os:unsetenv(Var).
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test_whitespace_proxy_env(Var, _State) ->
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os:putenv(Var, " "),
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%% Clear cached values first
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application:unset_env(hackney, http_proxy),
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application:unset_env(hackney, https_proxy),
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%% This should not crash and should return false (no proxy)
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Result = hackney:get_proxy_env(http),
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?assertEqual(false, Result),
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os:unsetenv(Var).
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test_multiple_spaces_proxy_env(Var, _State) ->
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os:putenv(Var, " \t \n "),
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%% Clear cached values first
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application:unset_env(hackney, http_proxy),
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application:unset_env(hackney, https_proxy),
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%% This should not crash and should return false (no proxy)
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Result = hackney:get_proxy_env(http),
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?assertEqual(false, Result),
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os:unsetenv(Var).
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test_valid_proxy_env(Var, _State) ->
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ProxyUrl = "http://proxy.example.com:8080",
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os:putenv(Var, ProxyUrl),
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%% Clear cached values first
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application:unset_env(hackney, http_proxy),
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application:unset_env(hackney, https_proxy),
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%% This should return the proxy URL
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Result = hackney:get_proxy_env(http),
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?assertEqual({ok, ProxyUrl}, Result),
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os:unsetenv(Var).
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test_valid_proxy_with_spaces(Var, _State) ->
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ProxyUrl = " http://proxy.example.com:8080 ",
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ExpectedUrl = "http://proxy.example.com:8080",
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os:putenv(Var, ProxyUrl),
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%% Clear cached values first
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application:unset_env(hackney, http_proxy),
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application:unset_env(hackney, https_proxy),
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%% This should return the proxy URL with stripped spaces
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Result = hackney:get_proxy_env(http),
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?assertEqual({ok, ExpectedUrl}, Result),
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os:unsetenv(Var).
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%% Test that empty proxy doesn't cause crash in actual request
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integration_empty_proxy_test_() ->
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{setup,
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fun() ->
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setup(),
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{ok, _} = application:ensure_all_started(hackney)
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end,
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fun(State) ->
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teardown(State),
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application:stop(hackney)
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end,
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fun(_) ->
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[
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{"Request with empty http_proxy", fun test_request_with_empty_proxy/0},
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{"Request with whitespace https_proxy", fun test_request_with_whitespace_proxy/0}
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]
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end}.
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test_request_with_empty_proxy() ->
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os:putenv("http_proxy", ""),
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%% This request should not crash
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{ok, StatusCode, _Headers, Ref} = hackney:request(get, "http://httpbin.org/status/200"),
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?assertEqual(200, StatusCode),
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hackney:close(Ref),
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os:unsetenv("http_proxy").
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test_request_with_whitespace_proxy() ->
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os:putenv("https_proxy", " "),
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%% This request should not crash
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{ok, StatusCode, _Headers, Ref} = hackney:request(get, "https://httpbin.org/status/200"),
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?assertEqual(200, StatusCode),
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hackney:close(Ref),
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os:unsetenv("https_proxy").

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