feat: detect HTTP library User-Agents and return plain text responses

src/cli_detect.rs

@@ -1,79 +0,0 @@
-const CLI_PREFIXES: &[&str] = &[
-    "curl/",
-    "Wget/",
-    "HTTPie/",
-    "xh/",
-    "fetch",
-    "PowerShell/",
-    "WindowsPowerShell/",
-];
-
-pub fn is_cli_user_agent(user_agent: &str) -> bool {
-    CLI_PREFIXES
-        .iter()
-        .any(|prefix| user_agent.starts_with(prefix))
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn detects_curl() {
-        assert!(is_cli_user_agent("curl/8.7.1"));
-    }
-
-    #[test]
-    fn detects_wget() {
-        assert!(is_cli_user_agent("Wget/1.21.4"));
-    }
-
-    #[test]
-    fn detects_httpie() {
-        assert!(is_cli_user_agent("HTTPie/3.2.2"));
-    }
-
-    #[test]
-    fn detects_xh() {
-        assert!(is_cli_user_agent("xh/0.22.0"));
-    }
-
-    #[test]
-    fn detects_fetch() {
-        assert!(is_cli_user_agent("fetch libfetch/2.0"));
-    }
-
-    #[test]
-    fn detects_powershell() {
-        assert!(is_cli_user_agent("PowerShell/7.4.1"));
-    }
-
-    #[test]
-    fn detects_windows_powershell() {
-        assert!(is_cli_user_agent("WindowsPowerShell/5.1"));
-    }
-
-    #[test]
-    fn rejects_browser() {
-        assert!(!is_cli_user_agent(
-            "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36"
-        ));
-    }
-
-    #[test]
-    fn rejects_empty() {
-        assert!(!is_cli_user_agent(""));
-    }
-
-    #[test]
-    fn matching_is_case_sensitive() {
-        // Real CLI tools send consistent casing; we intentionally do not
-        // match case-insensitively to avoid false positives.
-        assert!(!is_cli_user_agent("CURL/8.7.1"));
-        assert!(!is_cli_user_agent("Curl/8.7.1"));
-        assert!(!is_cli_user_agent("WGET/1.21.4"));
-        assert!(!is_cli_user_agent("httpie/3.2.2"));
-        assert!(!is_cli_user_agent("XH/0.22.0"));
-        assert!(!is_cli_user_agent("powershell/7.4.1"));
-    }
-}

src/handlers.rs

@@ -6,7 +6,7 @@ use axum::extract::{Path, Query, State};
 use axum::http::{HeaderMap, StatusCode, header};
 use axum::response::{Html, IntoResponse, Redirect, Response};
 
-use crate::cli_detect::is_cli_user_agent;
+use crate::ua_detect::is_plain_text_agent;
 use crate::db::{self, SharedDb};
 use crate::error::AppError;
 use crate::i18n::{self, Locale};
@@ -449,7 +449,7 @@ pub async fn root_redirect(
         .unwrap_or("");
 
     // CLI clients and JSON requests bypass i18n entirely.
-    if is_cli_user_agent(ua) && query.ip.is_none() {
+    if is_plain_text_agent(ua) && query.ip.is_none() {
         return match extract_client_ip(&headers, state.dev_mode) {
             Ok(ip) => format!("{ip}\n").into_response(),
             Err(e) => e.into_response(),
@@ -515,7 +515,7 @@ pub async fn root(
         .and_then(|v| v.to_str().ok())
         .unwrap_or("");
 
-    if is_cli_user_agent(ua) && query.ip.is_none() {
+    if is_plain_text_agent(ua) && query.ip.is_none() {
         return match extract_client_ip(&headers, state.dev_mode) {
             Ok(ip) => format!("{ip}\n").into_response(),
             Err(e) => e.into_response(),

src/lib.rs

@@ -1,4 +1,4 @@
-pub mod cli_detect;
+pub mod ua_detect;
 pub mod config;
 pub mod db;
 pub mod error;

src/ua_detect.rs

@@ -0,0 +1,290 @@
+const CLI_PREFIXES: &[&str] = &[
+    "curl/",
+    "Wget/",
+    "HTTPie/",
+    "xh/",
+    "fetch",
+    "PowerShell/",
+    "WindowsPowerShell/",
+];
+
+const HTTP_LIB_PREFIXES: &[&str] = &[
+    // Python
+    "python-requests/",
+    "python-httpx/",
+    "python-urllib3/",
+    "aiohttp/",
+    "httplib2/",
+    // Go
+    "Go-http-client/",
+    // Ruby
+    "rest-client/",
+    "Ruby",
+    "Faraday v",
+    "HTTParty/",
+    // Java / JVM
+    "Java/",
+    "Apache-HttpClient/",
+    "okhttp/",
+    // .NET / C#
+    "HttpClient/",
+    // Node.js
+    "node-fetch/",
+    "axios/",
+    "undici",
+    "got (",
+    // PHP
+    "GuzzleHttp/",
+    "Symfony HttpClient/",
+    // Rust
+    "reqwest/",
+    "hyper/",
+    "ureq/",
+    // Dart / Flutter
+    "Dart/",
+    // Perl
+    "libwww-perl/",
+    "LWP::Simple/",
+    // R
+    "libcurl/",
+    "httr/",
+    // Elixir
+    "hackney/",
+    "mint/",
+];
+
+fn is_cli_user_agent(user_agent: &str) -> bool {
+    CLI_PREFIXES
+        .iter()
+        .any(|prefix| user_agent.starts_with(prefix))
+}
+
+fn is_http_lib_user_agent(user_agent: &str) -> bool {
+    HTTP_LIB_PREFIXES
+        .iter()
+        .any(|prefix| user_agent.starts_with(prefix))
+}
+
+pub fn is_plain_text_agent(user_agent: &str) -> bool {
+    is_cli_user_agent(user_agent) || is_http_lib_user_agent(user_agent)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // --- CLI detection ---
+
+    #[test]
+    fn detects_curl() {
+        assert!(is_plain_text_agent("curl/8.7.1"));
+    }
+
+    #[test]
+    fn detects_wget() {
+        assert!(is_plain_text_agent("Wget/1.21.4"));
+    }
+
+    #[test]
+    fn detects_httpie() {
+        assert!(is_plain_text_agent("HTTPie/3.2.2"));
+    }
+
+    #[test]
+    fn detects_xh() {
+        assert!(is_plain_text_agent("xh/0.22.0"));
+    }
+
+    #[test]
+    fn detects_fetch() {
+        assert!(is_plain_text_agent("fetch libfetch/2.0"));
+    }
+
+    #[test]
+    fn detects_powershell() {
+        assert!(is_plain_text_agent("PowerShell/7.4.1"));
+    }
+
+    #[test]
+    fn detects_windows_powershell() {
+        assert!(is_plain_text_agent("WindowsPowerShell/5.1"));
+    }
+
+    #[test]
+    fn rejects_browser() {
+        assert!(!is_plain_text_agent(
+            "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36"
+        ));
+    }
+
+    #[test]
+    fn rejects_empty() {
+        assert!(!is_plain_text_agent(""));
+    }
+
+    #[test]
+    fn cli_matching_is_case_sensitive() {
+        assert!(!is_plain_text_agent("CURL/8.7.1"));
+        assert!(!is_plain_text_agent("Curl/8.7.1"));
+        assert!(!is_plain_text_agent("WGET/1.21.4"));
+        assert!(!is_plain_text_agent("httpie/3.2.2"));
+        assert!(!is_plain_text_agent("XH/0.22.0"));
+        assert!(!is_plain_text_agent("powershell/7.4.1"));
+    }
+
+    // --- HTTP library detection ---
+
+    #[test]
+    fn detects_python_requests() {
+        assert!(is_plain_text_agent("python-requests/2.31.0"));
+    }
+
+    #[test]
+    fn detects_python_httpx() {
+        assert!(is_plain_text_agent("python-httpx/0.27.0"));
+    }
+
+    #[test]
+    fn detects_python_urllib3() {
+        assert!(is_plain_text_agent("python-urllib3/2.2.1"));
+    }
+
+    #[test]
+    fn detects_aiohttp() {
+        assert!(is_plain_text_agent("aiohttp/3.9.5"));
+    }
+
+    #[test]
+    fn detects_httplib2() {
+        assert!(is_plain_text_agent("httplib2/0.22.0"));
+    }
+
+    #[test]
+    fn detects_go_http_client() {
+        assert!(is_plain_text_agent("Go-http-client/2.0"));
+    }
+
+    #[test]
+    fn detects_ruby_rest_client() {
+        assert!(is_plain_text_agent("rest-client/2.1.0 (linux x86_64)"));
+    }
+
+    #[test]
+    fn detects_ruby_default() {
+        assert!(is_plain_text_agent("Ruby"));
+    }
+
+    #[test]
+    fn detects_faraday() {
+        assert!(is_plain_text_agent("Faraday v2.9.0"));
+    }
+
+    #[test]
+    fn detects_httparty() {
+        assert!(is_plain_text_agent("HTTParty/0.21.0"));
+    }
+
+    #[test]
+    fn detects_java() {
+        assert!(is_plain_text_agent("Java/17.0.6"));
+    }
+
+    #[test]
+    fn detects_apache_http_client() {
+        assert!(is_plain_text_agent(
+            "Apache-HttpClient/4.5.14 (Java/17.0.6)"
+        ));
+    }
+
+    #[test]
+    fn detects_okhttp() {
+        assert!(is_plain_text_agent("okhttp/4.12.0"));
+    }
+
+    #[test]
+    fn detects_dotnet_http_client() {
+        assert!(is_plain_text_agent("HttpClient/8.0"));
+    }
+
+    #[test]
+    fn detects_node_fetch() {
+        assert!(is_plain_text_agent("node-fetch/3.3.2"));
+    }
+
+    #[test]
+    fn detects_axios() {
+        assert!(is_plain_text_agent("axios/1.7.2"));
+    }
+
+    #[test]
+    fn detects_undici() {
+        assert!(is_plain_text_agent("undici"));
+    }
+
+    #[test]
+    fn detects_got() {
+        assert!(is_plain_text_agent(
+            "got (https://github.com/sindresorhus/got)"
+        ));
+    }
+
+    #[test]
+    fn detects_guzzle() {
+        assert!(is_plain_text_agent("GuzzleHttp/7.8.1 curl/8.4.0 PHP/8.3.3"));
+    }
+
+    #[test]
+    fn detects_symfony_http_client() {
+        assert!(is_plain_text_agent("Symfony HttpClient/Curl"));
+    }
+
+    #[test]
+    fn detects_reqwest() {
+        assert!(is_plain_text_agent("reqwest/0.12.4"));
+    }
+
+    #[test]
+    fn detects_hyper() {
+        assert!(is_plain_text_agent("hyper/1.3.1"));
+    }
+
+    #[test]
+    fn detects_ureq() {
+        assert!(is_plain_text_agent("ureq/2.9.7"));
+    }
+
+    #[test]
+    fn detects_dart() {
+        assert!(is_plain_text_agent("Dart/3.3 (dart:io)"));
+    }
+
+    #[test]
+    fn detects_libwww_perl() {
+        assert!(is_plain_text_agent("libwww-perl/6.72"));
+    }
+
+    #[test]
+    fn detects_lwp_simple() {
+        assert!(is_plain_text_agent("LWP::Simple/6.72"));
+    }
+
+    #[test]
+    fn detects_libcurl() {
+        assert!(is_plain_text_agent("libcurl/8.4.0"));
+    }
+
+    #[test]
+    fn detects_httr() {
+        assert!(is_plain_text_agent("httr/1.4.7"));
+    }
+
+    #[test]
+    fn detects_hackney() {
+        assert!(is_plain_text_agent("hackney/1.20.1"));
+    }
+
+    #[test]
+    fn detects_mint() {
+        assert!(is_plain_text_agent("mint/1.5.2"));
+    }
+}

tests/integration.rs

@@ -394,6 +394,119 @@ async fn ipv6_via_cf_header() {
     assert_eq!(body.trim(), "2606:4700:4700::1111");
 }
 
+#[tokio::test]
+async fn python_requests_returns_plain_ip() {
+    let app = build_test_app();
+    let (status, body) = get_with_headers(
+        &app,
+        "/",
+        vec![
+            ("User-Agent", "python-requests/2.31.0"),
+            ("CF-Connecting-IP", "1.2.3.4"),
+        ],
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(body.trim(), "1.2.3.4");
+}
+
+#[tokio::test]
+async fn go_http_client_returns_plain_ip() {
+    let app = build_test_app();
+    let (status, body) = get_with_headers(
+        &app,
+        "/",
+        vec![
+            ("User-Agent", "Go-http-client/2.0"),
+            ("CF-Connecting-IP", "1.2.3.4"),
+        ],
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(body.trim(), "1.2.3.4");
+}
+
+#[tokio::test]
+async fn axios_returns_plain_ip() {
+    let app = build_test_app();
+    let (status, body) = get_with_headers(
+        &app,
+        "/",
+        vec![
+            ("User-Agent", "axios/1.7.2"),
+            ("CF-Connecting-IP", "1.2.3.4"),
+        ],
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(body.trim(), "1.2.3.4");
+}
+
+#[tokio::test]
+async fn guzzle_returns_plain_ip() {
+    let app = build_test_app();
+    let (status, body) = get_with_headers(
+        &app,
+        "/",
+        vec![
+            ("User-Agent", "GuzzleHttp/7.8.1 curl/8.4.0 PHP/8.3.3"),
+            ("CF-Connecting-IP", "1.2.3.4"),
+        ],
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(body.trim(), "1.2.3.4");
+}
+
+#[tokio::test]
+async fn reqwest_returns_plain_ip() {
+    let app = build_test_app();
+    let (status, body) = get_with_headers(
+        &app,
+        "/",
+        vec![
+            ("User-Agent", "reqwest/0.12.4"),
+            ("CF-Connecting-IP", "1.2.3.4"),
+        ],
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(body.trim(), "1.2.3.4");
+}
+
+#[tokio::test]
+async fn http_lib_on_lang_path_returns_plain_ip() {
+    let app = build_test_app();
+    let (status, body) = get_with_headers(
+        &app,
+        "/en",
+        vec![
+            ("User-Agent", "python-requests/2.31.0"),
+            ("CF-Connecting-IP", "1.2.3.4"),
+        ],
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(body.trim(), "1.2.3.4");
+}
+
+#[tokio::test]
+async fn http_lib_with_query_param_returns_html() {
+    let app = build_test_app();
+    let (status, body) = get_with_headers(
+        &app,
+        "/en?ip=45.77.77.77",
+        vec![
+            ("User-Agent", "python-requests/2.31.0"),
+            ("CF-Connecting-IP", "1.2.3.4"),
+        ],
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert!(body.contains("<!DOCTYPE html>"));
+    assert!(body.contains("45.77.77.77"));
+}
+
 // --- Edge case tests ---
 
 #[tokio::test]