Fetchable dapps (#1949)

* Fetching dapp from github.

* Unpacking dapp

* Removing hardcodes

* Proper Host validation

* Randomizing paths

* Splitting into files

* Serving donwloaded apps from different path

* Extracting URLHint to separate module

* Whitespace and docs

dapps/src/apps/urlhint.rs

@@ -0,0 +1,104 @@
+// 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 rustc_serialize::hex::ToHex;
+
+use util::{Address, FromHex};
+
+const COMMIT_LEN: usize = 20;
+
+#[derive(Debug)]
+pub struct GithubApp {
+	pub account: String,
+	pub repo: String,
+	pub commit: [u8;COMMIT_LEN],
+	pub owner: Address,
+}
+
+impl GithubApp {
+	pub fn url(&self) -> String {
+		// format!("https://github.com/{}/{}/archive/{}.zip", self.account, self.repo, self.commit.to_hex())
+		format!("http://github.todr.me/{}/{}/zip/{}", self.account, self.repo, self.commit.to_hex())
+	}
+
+	fn commit(bytes: &[u8]) -> Option<[u8;COMMIT_LEN]> {
+		if bytes.len() < COMMIT_LEN {
+			return None;
+		}
+
+		let mut commit = [0; COMMIT_LEN];
+		for i in 0..COMMIT_LEN {
+			commit[i] = bytes[i];
+		}
+
+		Some(commit)
+	}
+}
+
+pub trait URLHint {
+	fn resolve(&self, app_id: &str) -> Option<GithubApp>;
+}
+
+pub struct URLHintContract;
+
+impl URLHint for URLHintContract {
+	fn resolve(&self, app_id: &str) -> Option<GithubApp> {
+		// TODO [todr] use GithubHint contract to check the details
+		// For now we are just accepting patterns: <commithash>.<repo>.<account>.parity
+		let mut app_parts = app_id.split('.');
+
+		let hash = app_parts.next()
+			.and_then(|h| h.from_hex().ok())
+			.and_then(|h| GithubApp::commit(&h));
+		let repo = app_parts.next();
+		let account = app_parts.next();
+
+		match (hash, repo, account) {
+			(Some(hash), Some(repo), Some(account)) => {
+				Some(GithubApp {
+					account: account.into(),
+					repo: repo.into(),
+					commit: hash,
+					owner: Address::default(),
+				})
+			},
+			_ => None,
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::GithubApp;
+	use util::Address;
+
+	#[test]
+	fn should_return_valid_url() {
+		// given
+		let app = GithubApp {
+			account: "test".into(),
+			repo: "xyz".into(),
+			commit: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19],
+			owner: Address::default(),
+		};
+
+		// when
+		let url = app.url();
+
+		// then
+		assert_eq!(url, "http://github.todr.me/test/xyz/zip/000102030405060708090a0b0c0d0e0f10111213".to_owned());
+	}
+}