00d5562650
Stefan Eissing
2026-06-26
Subject
proxy: optimized env lookups
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lib/proxy.c+49 -46
| @@ -282,8 +282,6 @@ UNITTEST bool proxy_check_noproxy(const char *name, const char *no_proxy) | |
| static char *proxy_detect_proxy(struct Curl_easy *data, | |
| const struct Curl_scheme *scheme) | |
| { | |
| - | char *proxy = NULL; |
| - | |
| /* If proxy was not specified, we check for default proxy environment | |
| * variables, to enable i.e Lynx compliance: | |
| * | |
| @@ -301,58 +299,63 @@ static char *proxy_detect_proxy(struct Curl_easy *data, | |
| * For compatibility, the all-uppercase versions of these variables are | |
| * checked if the lowercase versions do not exist. | |
| */ | |
| - | char proxy_env[20]; |
| - | const char *envp; |
| - | VERBOSE(envp = proxy_env); |
| - | |
| - | curl_msnprintf(proxy_env, sizeof(proxy_env), "%s_proxy", scheme->name); |
| - | |
| - | /* read the protocol proxy: */ |
| - | proxy = curl_getenv(proxy_env); |
| + | const char *env_name = NULL; |
| + | char *proxy = NULL; |
| + | char name_buf[20]; |
| + | |
| + | /* Try scheme specific env var first, unless http(s). |
| + | * lowercase first, then uppercase. */ |
| + | if((scheme != &Curl_scheme_https) && (scheme != &Curl_scheme_http)) { |
| + | curl_msnprintf(name_buf, sizeof(name_buf), "%s_proxy", scheme->name); |
| + | env_name = name_buf; |
| + | proxy = curl_getenv(env_name); |
| + | if(!proxy) { |
| + | Curl_strntoupper(name_buf, name_buf, sizeof(name_buf)); |
| + | proxy = curl_getenv(env_name); |
| + | } |
| + | } |
| - | /* |
| - | * We do not try the uppercase version of HTTP_PROXY because of |
| - | * security reasons: |
| - | * |
| - | * When curl is used in a webserver application |
| - | * environment (cgi or php), this environment variable can |
| - | * be controlled by the web server user by setting the |
| - | * http header 'Proxy:' to some value. |
| - | * |
| - | * This can cause 'internal' http/ftp requests to be |
| - | * arbitrarily redirected by any external attacker. |
| - | */ |
| - | if(!proxy && !curl_strequal("http_proxy", proxy_env)) { |
| - | /* There was no lowercase variable, try the uppercase version: */ |
| - | Curl_strntoupper(proxy_env, proxy_env, sizeof(proxy_env)); |
| - | proxy = curl_getenv(proxy_env); |
| + | if(!proxy && |
| + | ((scheme == &Curl_scheme_https) || (scheme == &Curl_scheme_wss))) { |
| + | /* Not found, check 'https' env vars, also for 'wss'. |
| + | * Again, first lowercase then uppercase. */ |
| + | env_name = "https_proxy"; |
| + | proxy = curl_getenv(env_name); |
| + | if(!proxy) { |
| + | env_name = "HTTPS_PROXY"; |
| + | proxy = curl_getenv(env_name); |
| + | } |
| + | } |
| + | else if(!proxy && |
| + | ((scheme == &Curl_scheme_http) || (scheme == &Curl_scheme_ws))) { |
| + | /* Not found, check 'http' env vars, also for 'ws'. |
| + | * We do NOT try the uppercase version 'HTTP_PROXY' because of |
| + | * security reasons: |
| + | * |
| + | * When curl is used in a webserver application |
| + | * environment (cgi or php), this environment variable can |
| + | * be controlled by the web server user by setting the |
| + | * http header 'Proxy:' to some value. |
| + | * |
| + | * This can cause 'internal' http/ftp requests to be |
| + | * arbitrarily redirected by any external attacker. |
| + | */ |
| + | env_name = "http_proxy"; |
| + | proxy = curl_getenv(env_name); |
| } | |
| if(!proxy) { | |
| - | #ifndef CURL_DISABLE_WEBSOCKETS |
| - | /* websocket proxy fallbacks */ |
| - | if(curl_strequal("ws_proxy", proxy_env)) { |
| - | proxy = curl_getenv("http_proxy"); |
| - | } |
| - | else if(curl_strequal("wss_proxy", proxy_env)) { |
| - | proxy = curl_getenv("https_proxy"); |
| - | if(!proxy) |
| - | proxy = curl_getenv("HTTPS_PROXY"); |
| - | } |
| + | /* still not found, last resort checks. */ |
| + | env_name = "all_proxy"; |
| + | proxy = curl_getenv(env_name); |
| if(!proxy) { | |
| - | #endif |
| - | envp = "all_proxy"; |
| - | proxy = curl_getenv(envp); /* default proxy to use */ |
| - | if(!proxy) { |
| - | envp = "ALL_PROXY"; |
| - | proxy = curl_getenv(envp); |
| - | } |
| - | #ifndef CURL_DISABLE_WEBSOCKETS |
| + | env_name = "ALL_PROXY"; |
| + | proxy = curl_getenv(env_name); |
| } | |
| - | #endif |
| } | |
| + | |
| if(proxy) | |
| - | infof(data, "Uses proxy env variable %s == '%s'", envp, proxy); |
| + | infof(data, "Uses proxy env variable %s == '%s'", env_name, proxy); |
| return proxy; | |
| } | |