Middleware to decode content encoding

Provide tests and documentation.

docs/middlewares/index.rst

@@ -3,5 +3,6 @@ Middlewares
 
 .. toctree::
     basepath
+    decode
     server-sent-events
     subdomain

examples/app/app.vala

@@ -33,6 +33,8 @@ public async void respond_async (VSGI.Request req, VSGI.Response res) throws Err
 
 var app = new Router ();
 
+app.use (decode ());
+
 app.use ((req, res, next) => {
 	res.headers.append ("Server", "Valum/1.0");
 	HashTable<string, string>? @params = new HashTable<string, string> (str_hash, str_equal);

src/valum/valum-decode.vala

@@ -0,0 +1,86 @@
+/*
+ * This file is part of Valum.
+ *
+ * Valum is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * Valum is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Valum.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+using GLib;
+using VSGI;
+
+namespace Valum {
+
+	public enum DecodeFlags {
+		/**
+		 * @since 0.3
+		 */
+		NONE,
+		/**
+		 * Forward with the remaining content encodings if they are expected to
+		 * be processed later.
+		 *
+		 * @since 0.3
+		 */
+		FORWARD_REMAINING_ENCODINGS
+	}
+
+	/**
+	 * Decode any applied 'Content-Encoding'.
+	 *
+	 * Supports 'gzip', 'deflate' and 'identity', otherwise raise a
+	 * {@link Valum.ServerError.NOT_IMPLEMENTED}.
+	 *
+	 * @since 0.3
+	 */
+	public HandlerCallback decode (DecodeFlags flags = DecodeFlags.NONE) {
+		return (req, res, next, ctx) => {
+			var encodings = Soup.header_parse_list (req.headers.get_list ("Content-Encoding") ?? "");
+
+			// decode is in the opposite order of application
+			encodings.reverse ();
+
+			req.headers.remove ("Content-Encoding");
+
+			for (unowned SList<string> encoding = encodings; encoding != null; encoding = encoding.next) {
+				switch (encoding.data.down ()) {
+					case "gzip":
+					case "x-gzip":
+						req.headers.set_encoding (Soup.Encoding.EOF);
+						req.convert (new ZlibDecompressor (ZlibCompressorFormat.GZIP));
+						break;
+					case "deflate":
+						req.headers.set_encoding (Soup.Encoding.EOF);
+						req.convert (new ZlibDecompressor (ZlibCompressorFormat.RAW));
+						break;
+					case "identity":
+						// nothing to do, let's take a break ;)
+						break;
+					default:
+						// reapply remaining encodings
+						encoding.reverse ();
+						foreach (var remaining in encoding) {
+							req.headers.append ("Content-Encoding", remaining);
+						}
+						if (DecodeFlags.FORWARD_REMAINING_ENCODINGS in flags) {
+							return next ();
+						} else {
+							throw new ServerError.NOT_IMPLEMENTED ("The '%s' encoding is not supported.",
+							                                       encoding.data);
+						}
+				}
+			}
+
+			return next ();
+		};
+	}
+}

tests/decode-test.vala

@@ -0,0 +1,144 @@
+/*
+ * This file is part of Valum.
+ *
+ * Valum is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * Valum is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Valum.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+using Valum;
+using VSGI.Mock;
+
+/**
+ * @since 0.3
+ */
+public void test_decode_gzip () {
+	var req = new Request.with_method ("POST", new Soup.URI ("http://127.0.0.1/"));
+	var res = new Response (req);
+
+	req.headers.append ("Content-Encoding", "gzip");
+
+	assert ("gzip" == req.headers.get_list ("Content-Encoding"));
+
+	try {
+		decode () (req, res, () => {
+			assert (null == req.headers.get_list ("Content-Encoding"));
+			return true;
+		}, new Context ());
+	} catch (Error err) {
+		assert_not_reached ();
+	}
+}
+
+/**
+ * @since 0.3
+ */
+public void test_decode_xgzip () {
+	var req = new Request.with_method ("POST", new Soup.URI ("http://127.0.0.1/"));
+	var res = new Response (req);
+
+	req.headers.append ("Content-Encoding", "x-gzip");
+
+	assert ("x-gzip" == req.headers.get_list ("Content-Encoding"));
+
+	try {
+		decode () (req, res, () => {
+			assert (null == req.headers.get_list ("Content-Encoding"));
+			return true;
+		}, new Context ());
+	} catch (Error err) {
+		assert_not_reached ();
+	}
+}
+
+/**
+ * @since 0.3
+ */
+public void test_decode_deflate () {
+	var req = new Request.with_method ("POST", new Soup.URI ("http://127.0.0.1/"));
+	var res = new Response (req);
+
+	req.headers.append ("Content-Encoding", "deflate");
+
+	assert ("deflate" == req.headers.get_list ("Content-Encoding"));
+
+	try {
+		decode () (req, res, () => {
+			assert (null == req.headers.get_list ("Content-Encoding"));
+			return true;
+		}, new Context ());
+	} catch (Error err) {
+		assert_not_reached ();
+	}
+}
+
+/**
+ * @since 0.3
+ */
+public void test_decode_identity () {
+	var req = new Request.with_method ("POST", new Soup.URI ("http://127.0.0.1/"));
+	var res = new Response (req);
+
+	req.headers.append ("Content-Encoding", "identity");
+
+	assert ("identity" == req.headers.get_list ("Content-Encoding"));
+
+	try {
+		decode () (req, res, () => {
+			assert (null == req.headers.get_list ("Content-Encoding"));
+			return true;
+		}, new Context ());
+	} catch (Error err) {
+		assert_not_reached ();
+	}
+}
+
+/**
+ * @since 0.3
+ */
+public void test_decode_unknown_encoding () {
+	var req = new Request.with_method ("POST", new Soup.URI ("http://127.0.0.1/"));
+	var res = new Response (req);
+
+	req.headers.append ("Content-Encoding", "br, gzip");
+
+	try {
+		decode () (req, res, () => {
+			assert_not_reached ();
+		}, new Context ());
+		assert_not_reached ();
+	} catch (ServerError.NOT_IMPLEMENTED err) {
+		assert ("br" == req.headers.get_list ("Content-Encoding"));
+	} catch (Error err) {
+		assert_not_reached ();
+	}
+}
+
+/**
+ * @since 0.3
+ */
+public void test_decode_forward_remaining_encodings () {
+	var req = new Request.with_method ("POST", new Soup.URI ("http://127.0.0.1/"));
+	var res = new Response (req);
+
+	req.headers.append ("Content-Encoding", "gzip, br, deflate"); // brotli is not handled
+
+	try {
+		decode (DecodeFlags.FORWARD_REMAINING_ENCODINGS) (req, res, () => {
+			assert ("gzip, br" == req.headers.get_list ("Content-Encoding"));
+			return true;
+		}, new Context ());
+	} catch (Error err) {
+		assert_not_reached ();
+	}
+}
+

tests/tests.vala

@@ -103,6 +103,11 @@ public int main (string[] args) {
 	Test.add_func ("/route/match/not_matching", test_route_match_not_matching);
 	Test.add_func ("/route/fire", test_route_match_not_matching);
 
+	Test.add_func ("/decode/gzip", test_decode_gzip);
+	Test.add_func ("/decode/deflate", test_decode_deflate);
+	Test.add_func ("/decode/unknown_encoding", test_decode_unknown_encoding);
+	Test.add_func ("/decode/forward_remaining_encodings", test_decode_forward_remaining_encodings);
+
 	Test.add_func ("/subdomain", test_subdomain);
 	Test.add_func ("/subdomain/joker", test_subdomain_joker);
 	Test.add_func ("/subdomain/strict", test_subdomain_strict);