139 lines
4.9 KiB
C#
139 lines
4.9 KiB
C#
// SparkleShare, a collaboration and sharing tool.
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// Copyright (C) 2010 Hylke Bons <hi@planetpeanut.uk>
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation, either version 3 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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using System;
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using System.IO;
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using System.Security.Cryptography;
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namespace Sparkles {
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public abstract class SSHFetcher : BaseFetcher {
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public static string SSHKeyScan = "ssh-keyscan";
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protected SSHFetcher (SparkleFetcherInfo info) : base (info)
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{
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}
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public override bool Fetch ()
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{
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string host_key = FetchHostKey ();
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bool host_key_warning = false;
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if (string.IsNullOrEmpty (RemoteUrl.Host) || host_key == null) {
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Logger.LogInfo ("Auth", "Could not fetch host key");
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errors.Add ("error: Could not fetch host key");
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return false;
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}
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if (RequiredFingerprint != null) {
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string host_fingerprint = DeriveFingerprint (host_key);
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if (host_fingerprint == null || RequiredFingerprint!= host_fingerprint) {
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Logger.LogInfo ("Auth", "Fingerprint doesn't match");
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errors.Add ("error: Host fingerprint doesn't match");
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return false;
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}
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Logger.LogInfo ("Auth", "Fingerprint matches");
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} else {
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Logger.LogInfo ("Auth", "Skipping fingerprint check");
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host_key_warning = true;
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}
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AcceptHostKey (host_key, host_key_warning);
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return true;
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}
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string FetchHostKey ()
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{
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Logger.LogInfo ("Auth", string.Format ("Fetching host key for {0}", RemoteUrl.Host));
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var ssh_keyscan = new Command (SSHKeyScan, string.Format ("-t rsa -p 22 {0}", RemoteUrl.Host));
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if (RemoteUrl.Port > 0)
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ssh_keyscan.StartInfo.Arguments = string.Format ("-t rsa -p {0} {1}", RemoteUrl.Port, RemoteUrl.Host);
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string host_key = ssh_keyscan.StartAndReadStandardOutput ();
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if (ssh_keyscan.ExitCode == 0 && !string.IsNullOrWhiteSpace (host_key))
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return host_key;
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return null;
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}
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string DeriveFingerprint (string public_key)
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{
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try {
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SHA256 sha256 = new SHA256CryptoServiceProvider ();
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string key = public_key.Split (" ".ToCharArray ()) [2];
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byte [] base64_bytes = Convert.FromBase64String (key);
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byte [] sha256_bytes = sha256.ComputeHash (base64_bytes);
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string fingerprint = BitConverter.ToString (sha256_bytes);
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fingerprint = fingerprint.ToLower ().Replace ("-", ":");
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return fingerprint;
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} catch (Exception e) {
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Logger.LogInfo ("Fetcher", "Failed to create fingerprint: ", e);
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return null;
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}
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}
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void AcceptHostKey (string host_key, bool warn)
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{
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string ssh_config_path = Path.Combine (Configuration.DefaultConfiguration.DirectoryPath, "ssh");
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string known_hosts_file_path = Path.Combine (ssh_config_path, "known_hosts");
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if (!File.Exists (known_hosts_file_path)) {
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if (!Directory.Exists (ssh_config_path))
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Directory.CreateDirectory (ssh_config_path);
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File.Create (known_hosts_file_path).Close ();
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}
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string host = RemoteUrl.Host;
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string known_hosts = File.ReadAllText (known_hosts_file_path);
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string [] known_hosts_lines = File.ReadAllLines (known_hosts_file_path);
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foreach (string line in known_hosts_lines) {
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if (line.StartsWith (host + " ", StringComparison.InvariantCulture))
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return;
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}
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if (known_hosts.EndsWith ("\n", StringComparison.InvariantCulture))
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File.AppendAllText (known_hosts_file_path, host_key + "\n");
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else
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File.AppendAllText (known_hosts_file_path, "\n" + host_key + "\n");
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Logger.LogInfo ("Auth", "Accepted host key for " + host);
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if (warn)
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warnings.Add ("The following host key has been accepted:\n" + DeriveFingerprint (host_key));
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}
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}
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}
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