Verify known host fingerprints and warn about new ones

SparkleLib/Git/SparkleFetcherGit.cs

@@ -29,11 +29,11 @@ namespace SparkleLib.Git {
     public class SparkleFetcher : SparkleFetcherBase {
 
         private SparkleGit git;
-        private bool fetch_prior_history = false;
 
 
-        public SparkleFetcher (string server, string remote_path, string target_folder, bool fetch_prior_history) :
+        public SparkleFetcher (string server, string required_fingerprint, string remote_path,
-            base (server, remote_path, target_folder, fetch_prior_history)
+            string target_folder, bool fetch_prior_history) : base (server, required_fingerprint, remote_path,
+                target_folder, fetch_prior_history)
         {
             Uri uri = RemoteUrl; 
 
@@ -72,14 +72,12 @@ namespace SparkleLib.Git {
 
             TargetFolder = target_folder;
             RemoteUrl    = uri;
-
-            this.fetch_prior_history = fetch_prior_history;
         }
 
 
         public override bool Fetch ()
         {
-            if (this.fetch_prior_history) {
+            if (FetchPriorHistory) {
                 this.git = new SparkleGit (SparkleConfig.DefaultConfig.TmpPath,
                     "clone " +
                     "--progress " +
@@ -171,15 +169,10 @@ namespace SparkleLib.Git {
             string output = git.StandardOutput.ReadToEnd ().Trim ();
             git.WaitForExit ();
 
-            if (string.IsNullOrEmpty (output)) {
+            if (string.IsNullOrEmpty (output))
                 return;
-
+            else
-            } else {
+                Warnings.Add ("You seem to have a system wide ‘gitignore’ file, this may affect SparkleShare files.");
-                Warnings = new string [] {
-                    string.Format ("You seem to have configured a system wide ‘gitignore’ file. " +
-                                   "This may affect SparkleShare files:\n\n{0}", output)
-                };
-            }
         }
 
 

SparkleLib/SparkleConfig.cs

@@ -137,6 +137,7 @@ namespace SparkleLib {
             } finally {
                 Load (FullPath);
                 TmpPath = Path.Combine (FoldersPath, ".tmp");
+                Directory.CreateDirectory (TmpPath);
             }
         }
 

SparkleLib/SparkleFetcherBase.cs

@@ -16,8 +16,11 @@
 
 
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Security.Cryptography;
+using System.Text;
 using System.Text.RegularExpressions;
 using System.Threading;
 
@@ -42,15 +45,19 @@ namespace SparkleLib {
         public string TargetFolder;
         public Uri RemoteUrl;
         public string [] ExcludeRules;
-        public string [] Warnings;
+        public List<string> Warnings = new List<string> ();
         public bool IsActive { get; private set; }
+        public string RequiredFingerprint;
+        public bool FetchPriorHistory = false;
 
         private Thread thread;
 
 
-        public SparkleFetcherBase (string server, string remote_path,
+        public SparkleFetcherBase (string server, string required_fingerprint, string remote_path,
             string target_folder, bool fetch_prior_history)
         {
+            RequiredFingerprint = required_fingerprint;
+            FetchPriorHistory   = fetch_prior_history;
             remote_path         = remote_path.Trim ("/".ToCharArray ());
 
             if (server.EndsWith ("/"))
@@ -143,17 +150,19 @@ namespace SparkleLib {
         public void Start ()
         {
             IsActive = true;
-            SparkleHelpers.DebugInfo ("Fetcher", "[" + TargetFolder + "] Fetching folder: " + RemoteUrl);
 
             if (Started != null)
                 Started ();
 
+            SparkleHelpers.DebugInfo ("Fetcher", "[" + TargetFolder + "] Fetching folder: " + RemoteUrl);
+
             if (Directory.Exists (TargetFolder))
                 Directory.Delete (TargetFolder, true);
 
+
             string host = RemoteUrl.Host;
 
-            if (String.IsNullOrEmpty (host)) {
+            if (string.IsNullOrEmpty (host)) {
                 if (Failed != null)
                     Failed ();
 
@@ -163,8 +172,35 @@ namespace SparkleLib {
 
             string host_key = GetHostKey ();
 
-            if (host_key != null)
+            if (host_key == null) {
-                AcceptHostKey (host_key);
+                if (Failed != null)
+                    Failed ();
+
+                return;
+            }
+
+
+            bool warn = true;
+            if (RequiredFingerprint != null) {
+                string host_fingerprint = GetFingerprint (host_key);
+
+                if (!RequiredFingerprint.Equals (host_fingerprint)) {
+                    SparkleHelpers.DebugInfo ("Auth", "Fingerprint doesn't match");
+
+                    if (Failed != null)
+                        Failed ();
+
+                    return;
+                }
+
+                warn = false;
+                SparkleHelpers.DebugInfo ("Auth", "Fingerprint matches");
+
+            } else {
+               SparkleHelpers.DebugInfo ("Auth", "Skipping fingerprint check");
+            }
+
+            AcceptHostKey (host_key, warn);
 
 
             this.thread = new Thread (new ThreadStart (delegate {
@@ -175,7 +211,7 @@ namespace SparkleLib {
                     IsActive = false;
 
                     if (Finished != null)
-                        Finished (Warnings);
+                        Finished (Warnings.ToArray ());
 
                 } else {
                     Thread.Sleep (500);
@@ -228,7 +264,7 @@ namespace SparkleLib {
 
             // Reading the standard output HAS to go before
             // WaitForExit, or it will hang forever on output > 4096 bytes
-            string host_key = process.StandardOutput.ReadToEnd ().TrimEnd ();
+            string host_key = process.StandardOutput.ReadToEnd ().Trim ();
             process.WaitForExit ();
 
             if (process.ExitCode == 0)
@@ -238,7 +274,39 @@ namespace SparkleLib {
         }
 
 
-        private void AcceptHostKey (string host_key)
+        // FIXME: Calculate fingerprint natively: decode base64 -> md5
+        private string GetFingerprint (string public_key)
+        {
+            string tmp_file_path = Path.Combine (SparkleConfig.DefaultConfig.TmpPath, "hostkey.tmp");
+            File.WriteAllText (tmp_file_path, public_key + Environment.NewLine);
+
+            Process process = new Process () {
+                EnableRaisingEvents = true
+            };
+
+            process.StartInfo.WorkingDirectory       = SparkleConfig.DefaultConfig.TmpPath;
+            process.StartInfo.UseShellExecute        = false;
+            process.StartInfo.RedirectStandardOutput = true;
+            process.StartInfo.CreateNoWindow         = true;
+
+            process.StartInfo.FileName  = "ssh-keygen";
+            process.StartInfo.Arguments = "-lf " + tmp_file_path;
+
+            process.Start ();
+
+            // Reading the standard output HAS to go before
+            // WaitForExit, or it will hang forever on output > 4096 bytes
+            string fingerprint = process.StandardOutput.ReadToEnd ().Trim ();
+            process.WaitForExit ();
+
+            fingerprint = fingerprint.Substring (fingerprint.IndexOf (" ") + 1, 47);
+            File.Delete (tmp_file_path);
+
+            return fingerprint;
+        }
+
+
+        private void AcceptHostKey (string host_key, bool warn)
         {
             string ssh_config_path       = Path.Combine (SparkleConfig.DefaultConfig.HomePath, ".ssh");
             string known_hosts_file_path = Path.Combine (ssh_config_path, "known_hosts");
@@ -265,6 +333,11 @@ namespace SparkleLib {
                 File.AppendAllText (known_hosts_file_path, "\n" + host_key + "\n");
 
             SparkleHelpers.DebugInfo ("Auth", "Accepted host key for " + host);
+
+            if (warn) {
+                Warnings.Add ("The accepted fingerprint is:\n" + GetFingerprint (host_key) +
+                    "\n\nIf the above key doesn't match due to a possible attack, delete this project folder immediately.");
+            }
         }
     }
 }

SparkleLib/SparkleHelpers.cs

@@ -79,9 +79,8 @@ namespace SparkleLib {
         // Check if a file is a symbolic link
         public static bool IsSymlink (string file)
         {
-            FileAttributes attr = File.GetAttributes (file);
+            FileAttributes attributes = File.GetAttributes (file);
-
+            return ((attributes & FileAttributes.ReparsePoint) == FileAttributes.ReparsePoint);
-            return ((attr & FileAttributes.ReparsePoint) == FileAttributes.ReparsePoint);
         }
 
 
@@ -93,20 +92,13 @@ namespace SparkleLib {
         }
 
 
-        // Gets the relative path of two hierarchical absolute paths    
+        public static bool IsWindows {
-        public static string DiffPaths (string target, string source)
+            get {
-        {
-            return target.Replace (source + Path.DirectorySeparatorChar, "");      
-        }
-
-        public static bool IsWindows
-        {
-            get
-            {
                 PlatformID platform = Environment.OSVersion.Platform;
-                return (platform == PlatformID.Win32NT
+
-                    || platform == PlatformID.Win32S
+                return (platform == PlatformID.Win32NT ||
-                    || platform == PlatformID.Win32Windows);
+                        platform == PlatformID.Win32S  ||
+                        platform == PlatformID.Win32Windows);
             }
         }
     }

SparkleShare/Linux/SparkleSetup.cs

@@ -529,7 +529,7 @@ namespace SparkleShare {
                         };
 
 
-                        if (warnings != null) {
+                        if (warnings.Length > 0) {
                             Image warning_image = new Image (
                                 SparkleUIHelpers.GetIcon ("dialog-warning", 24)
                             );

SparkleShare/Mac/SparkleSetup.cs

@@ -610,7 +610,7 @@ namespace SparkleShare {
                                           "’ added!";
                             Description = "Access the files from your SparkleShare folder.";
     
-                            if (warnings != null) {
+                            if (warnings.Length > 0) {
                                 WarningImage = NSImage.ImageNamed ("NSCaution");
                                 WarningImage.Size = new SizeF (24, 24);
     

SparkleShare/SparkleControllerBase.cs

@@ -954,7 +954,7 @@ namespace SparkleShare {
         }
 
 
-        public void FetchFolder (string address, string remote_path, string announcements_url,
+        public void FetchFolder (string address, string required_fingerprint, string remote_path, string announcements_url,
             bool fetch_prior_history)
         {
             if (announcements_url != null)
@@ -986,6 +986,7 @@ namespace SparkleShare {
                 this.fetcher = (SparkleFetcherBase) Activator.CreateInstance (
                         Type.GetType ("SparkleLib." + backend + ".SparkleFetcher, SparkleLib." + backend),
                             address,
+                            required_fingerprint,
                             remote_path,
                             tmp_folder,
                             fetch_prior_history

SparkleShare/SparkleSetupController.cs

@@ -350,7 +350,7 @@ namespace SparkleShare {
             Program.Controller.FolderFetchError += AddPageFetchErrorDelegate;
             Program.Controller.FolderFetching   += SyncingPageFetchingDelegate;
 
-            Program.Controller.FetchFolder (address, remote_path,
+            Program.Controller.FetchFolder (address, SelectedPlugin.Fingerprint, remote_path,
                 SelectedPlugin.AnnouncementsUrl, this.fetch_prior_history);
         }
 
@@ -431,7 +431,7 @@ namespace SparkleShare {
             Program.Controller.FolderFetchError += InvitePageFetchErrorDelegate;
             Program.Controller.FolderFetching   += SyncingPageFetchingDelegate;
 
-            Program.Controller.FetchFolder (PendingInvite.Address,
+            Program.Controller.FetchFolder (PendingInvite.Address, PendingInvite.Fingerprint,
                 PendingInvite.RemotePath, PendingInvite.AnnouncementsUrl, false); // TODO: checkbox on invite page
         }
 

SparkleShare/Windows/SparkleSetup.cs

@@ -554,7 +554,7 @@ namespace SparkleShare {
                             Content = "Open folder"
                         };
 
-                        if (warnings != null) {
+                        if (warnings.Length > 0) {
 							Image warning_image = new Image () {
 								Source = Imaging.CreateBitmapSourceFromHIcon (Drawing.SystemIcons.Warning.Handle,
                                 	Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions ())