Host validation (again) (#1666)

* Revert "Revert "Validating Host headers in RPC requests" (#1663)"

This reverts commit 3cc3dbef66.

* Fixing binding on MacOS

dapps/src/router/host_validation.rs

@@ -0,0 +1,45 @@
+// Copyright 2015, 2016 Ethcore (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity 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 General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+
+use DAPPS_DOMAIN;
+use hyper::server;
+use hyper::net::HttpStream;
+
+use jsonrpc_http_server::{is_host_header_valid};
+use handlers::ContentHandler;
+
+
+pub fn is_valid(request: &server::Request<HttpStream>, bind_address: &str, endpoints: Vec<String>) -> bool {
+	let mut endpoints = endpoints.into_iter()
+		.map(|endpoint| format!("{}{}", endpoint, DAPPS_DOMAIN))
+		.collect::<Vec<String>>();
+	// Add localhost domain as valid too if listening on loopback interface.
+	endpoints.push(bind_address.replace("127.0.0.1", "localhost").into());
+	endpoints.push(bind_address.into());
+
+	is_host_header_valid(request, &endpoints)
+}
+
+pub fn host_invalid_response() -> Box<server::Handler<HttpStream> + Send> {
+	Box::new(ContentHandler::forbidden(
+		r#"
+		<h1>Request with disallowed <code>Host</code> header has been blocked.</h1>
+		<p>Check the URL in your browser address bar.</p>
+		"#.into(),
+		"text/html".into()
+	))
+}