[RFC] Certs and Creds from a managed smart subtransport

LibGit2Sharp.Tests/SmartSubtransportFixture.cs

@@ -4,6 +4,7 @@
 using System.Net;
 using System.Net.Security;
 using LibGit2Sharp.Tests.TestHelpers;
+using LibGit2Sharp.Core;
 using Xunit;
 using Xunit.Extensions;
 
@@ -76,6 +77,58 @@ public void CustomSmartSubtransportTest(string scheme, string url)
             }
         }
 
+        [Theory]
+        [InlineData("https", "https://bitbucket.org/libgit2/testgitrepository.git", "libgit3", "libgit3")]
+        public void CanUseCredentials(string scheme, string url, string user, string pass)
+        {
+            string remoteName = "testRemote";
+
+            var scd = BuildSelfCleaningDirectory();
+            var repoPath = Repository.Init(scd.RootedDirectoryPath);
+
+            SmartSubtransportRegistration<MockSmartSubtransport> registration = null;
+
+            try
+            {
+                // Disable server certificate validation for testing.
+                // Do *NOT* enable this in production.
+                ServicePointManager.ServerCertificateValidationCallback = certificateValidationCallback;
+
+                registration = GlobalSettings.RegisterSmartSubtransport<MockSmartSubtransport>(scheme);
+                Assert.NotNull(registration);
+
+                using (var repo = new Repository(scd.DirectoryPath))
+                {
+                    Remote remote = repo.Network.Remotes.Add(remoteName, url);
+
+                    // Set up structures for the expected results
+                    // and verifying the RemoteUpdateTips callback.
+                    TestRemoteInfo expectedResults = TestRemoteInfo.TestRemoteInstance;
+                    ExpectedFetchState expectedFetchState = new ExpectedFetchState(remoteName);
+
+                    // Add expected branch objects
+                    foreach (KeyValuePair<string, ObjectId> kvp in expectedResults.BranchTips)
+                    {
+                        expectedFetchState.AddExpectedBranch(kvp.Key, ObjectId.Zero, kvp.Value);
+                    }
+
+                    // Perform the actual fetch
+                    repo.Network.Fetch(remote, new FetchOptions { OnUpdateTips = expectedFetchState.RemoteUpdateTipsHandler, TagFetchMode = TagFetchMode.Auto,
+                        CredentialsProvider = (_user, _valid, _hostname) => new UsernamePasswordCredentials() { Username = "libgit3", Password = "libgit3" },
+                    });
+
+                    // Verify the expected
+                    expectedFetchState.CheckUpdatedReferences(repo);
+                }
+            }
+            finally
+            {
+                GlobalSettings.UnregisterSmartSubtransport(registration);
+
+                ServicePointManager.ServerCertificateValidationCallback -= certificateValidationCallback;
+            }
+        }
+
         [Fact]
         public void CannotReregisterScheme()
         {
@@ -234,14 +287,39 @@ private HttpWebResponse GetResponseWithRedirects()
                             }
                         }
 
-                        response = (HttpWebResponse)request.GetResponse();
+                        try
+                        {
+                            response = (HttpWebResponse)request.GetResponse();
+                        }
+                        catch (WebException ex)
+                        {
+                            response = ex.Response as HttpWebResponse;
+                            if (response.StatusCode == HttpStatusCode.Unauthorized)
+                            {
+                                Credentials cred;
+                                int ret = SmartTransport.AcquireCredentials(out cred, null, typeof(UsernamePasswordCredentials));
+                                if (ret != 0)
+                                {
+                                    throw new InvalidOperationException("dunno");
+                                }
+
+                                request = CreateWebRequest(EndpointUrl, IsPost, ContentType);
+                                UsernamePasswordCredentials userpass = (UsernamePasswordCredentials)cred;
+                                request.Credentials = new NetworkCredential(userpass.Username, userpass.Password);
+                                continue;
+                            }
+
+                            // rethrow if it's not 401
+                            throw ex;
+                        }
 
                         if (response.StatusCode == HttpStatusCode.Moved || response.StatusCode == HttpStatusCode.Redirect)
                         {
                             request = CreateWebRequest(response.Headers["Location"], IsPost, ContentType);
                             continue;
                         }
 
+
                         break;
                     }
 

LibGit2Sharp/CertificateSsh.cs

@@ -1,4 +1,6 @@
 using LibGit2Sharp.Core;
+using System;
+using System.Runtime.InteropServices;
 
 namespace LibGit2Sharp
 {
@@ -49,5 +51,31 @@ internal CertificateSsh(GitCertificateSsh cert)
             HashSHA1 = new byte[20];
             cert.HashSHA1.CopyTo(HashSHA1, 0);
         }
+
+        internal IntPtr ToPointer()
+        {
+            GitCertificateSshType sshCertType = 0;
+            if (HasMD5)
+            {
+                sshCertType |= GitCertificateSshType.MD5;
+            }
+            if (HasSHA1)
+            {
+                sshCertType |= GitCertificateSshType.SHA1;
+            }
+
+            var gitCert = new GitCertificateSsh
+            {
+                cert_type = GitCertificateType.Hostkey,
+                type = sshCertType,
+            };
+            HashMD5.CopyTo(gitCert.HashMD5, 0);
+            HashSHA1.CopyTo(gitCert.HashSHA1, 0);
+
+            var ptr = Marshal.AllocHGlobal(Marshal.SizeOf(gitCert));
+            Marshal.StructureToPtr(gitCert, ptr, false);
+
+            return ptr;
+        }
     }
 }

LibGit2Sharp/CertificateX509.cs

@@ -1,4 +1,5 @@
-using System.Runtime.InteropServices;
+using System;
+using System.Runtime.InteropServices;
 using System.Security.Cryptography.X509Certificates;
 using LibGit2Sharp.Core;
 
@@ -28,5 +29,23 @@ internal CertificateX509(GitCertificateX509 cert)
             Marshal.Copy(cert.data, data, 0, len);
             Certificate = new X509Certificate(data);
         }
+
+        internal IntPtr ToPointers(out IntPtr dataPtr)
+        {
+            var certData = Certificate.Export(X509ContentType.Cert);
+            dataPtr = Marshal.AllocHGlobal(certData.Length);
+            Marshal.Copy(certData, 0, dataPtr, certData.Length);
+            var gitCert = new GitCertificateX509()
+            {
+                cert_type = GitCertificateType.X509,
+                data = dataPtr,
+                len = (UIntPtr)certData.LongLength,
+            };
+
+            var ptr = Marshal.AllocHGlobal(Marshal.SizeOf(gitCert));
+            Marshal.StructureToPtr(gitCert, ptr, false);
+
+            return ptr;
+        }
     }
 }

LibGit2Sharp/Core/GitCredential.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace LibGit2Sharp.Core
+{
+    [StructLayout(LayoutKind.Sequential)]
+    internal class GitCredential
+    {
+        public GitCredentialType credtype;
+        public IntPtr free;
+    }
+}
+

LibGit2Sharp/Core/GitCredentialUserpass.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace LibGit2Sharp.Core
+{
+    [StructLayout(LayoutKind.Sequential)]
+    internal class GitCredentialUserpass
+    {
+        public GitCredential parent;
+        public IntPtr username;
+        public IntPtr password;
+    }
+}
+

LibGit2Sharp/Core/NativeMethods.cs

@@ -459,6 +459,9 @@ internal static extern int git_cred_userpass_plaintext_new(
             [MarshalAs(UnmanagedType.CustomMarshaler, MarshalCookie = UniqueId.UniqueIdentifier, MarshalTypeRef = typeof(StrictUtf8Marshaler))] string username,
             [MarshalAs(UnmanagedType.CustomMarshaler, MarshalCookie = UniqueId.UniqueIdentifier, MarshalTypeRef = typeof(StrictUtf8Marshaler))] string password);
 
+        [DllImport(libgit2)]
+        internal static extern void git_cred_free(IntPtr cred);
+
         [DllImport(libgit2)]
         internal static extern int git_describe_commit(
             out DescribeResultSafeHandle describe,
@@ -1732,6 +1735,20 @@ internal static extern int git_transport_smart(
             IntPtr remote,
             IntPtr definition);
 
+        [DllImport(libgit2)]
+        internal static extern int git_transport_smart_certificate_check(
+            IntPtr transport,
+            IntPtr cert,
+            int valid,
+            [MarshalAs(UnmanagedType.CustomMarshaler, MarshalCookie = UniqueId.UniqueIdentifier, MarshalTypeRef = typeof(StrictUtf8Marshaler))] string hostname);
+
+        [DllImport(libgit2)]
+        internal static extern int git_transport_smart_credentials(
+            out IntPtr cred_out,
+            IntPtr transport,
+            [MarshalAs(UnmanagedType.CustomMarshaler, MarshalCookie = UniqueId.UniqueIdentifier, MarshalTypeRef = typeof(StrictUtf8Marshaler))] string user,
+            int methods);
+
         [DllImport(libgit2)]
         internal static extern int git_transport_unregister(
             [MarshalAs(UnmanagedType.CustomMarshaler, MarshalCookie = UniqueId.UniqueIdentifier, MarshalTypeRef = typeof(StrictUtf8Marshaler))] string prefix);

LibGit2Sharp/Core/Proxy.cs

@@ -628,6 +628,15 @@ public static ConfigurationSafeHandle git_config_snapshot(ConfigurationSafeHandl
 
         #endregion
 
+        #region git_cred_
+
+        public static void git_cred_free(IntPtr cred)
+        {
+            NativeMethods.git_cred_free(cred);
+        }
+
+        #endregion
+
         #region git_describe_
 
         public static string git_describe_commit(
@@ -3181,6 +3190,15 @@ public static void git_transport_unregister(String prefix)
 
         #endregion
 
+        #region git_transport_smart_
+
+        public static int git_transport_smart_credentials(out IntPtr cred, IntPtr transport, string user, int methods)
+        {
+            return NativeMethods.git_transport_smart_credentials(out cred, transport, user, methods);
+        }
+
+        #endregion
+
         #region git_tree_
 
         public static Mode git_tree_entry_attributes(SafeHandle entry)

LibGit2Sharp/LibGit2Sharp.csproj

@@ -383,6 +383,8 @@
     <Compile Include="Core\GitCertificateSshType.cs" />
     <Compile Include="CertificateSsh.cs" />
     <Compile Include="IDiffResult.cs" />
+    <Compile Include="Core\GitCredential.cs" />
+    <Compile Include="Core\GitCredentialUserpass.cs" />
   </ItemGroup>
   <ItemGroup>
     <CodeAnalysisDictionary Include="CustomDictionary.xml" />

LibGit2Sharp/SmartSubtransport.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Runtime.InteropServices;
+using System.Text;
 using LibGit2Sharp.Core;
+using LibGit2Sharp.Core.Handles;
 
 namespace LibGit2Sharp
 {
@@ -47,6 +49,76 @@ public abstract class RpcSmartSubtransport : SmartSubtransport
     /// </summary>
     public abstract class SmartSubtransport
     {
+        internal IntPtr Transport { get; set; }
+
+        /// <summary>
+        /// Call the certificate check callback
+        /// </summary>
+        /// <param name="cert">The certificate to send</param>
+        /// <param name="valid">Whether we consider the certificate to be valid</param>
+        /// <param name="hostname">The hostname we connected to</param>
+        public int CertificateCheck(Certificate cert, bool valid, string hostname)
+        {
+            CertificateSsh sshCert = cert as CertificateSsh;
+            CertificateX509 x509Cert = cert as CertificateX509;
+
+            if (sshCert == null && x509Cert == null)
+            {
+                throw new InvalidOperationException("Unsupported certificate type");
+            }
+
+            int ret;
+            if (sshCert != null)
+            {
+                var certPtr = sshCert.ToPointer();
+                ret = NativeMethods.git_transport_smart_certificate_check(Transport, certPtr, valid ? 1 : 0, hostname);
+                Marshal.FreeHGlobal(certPtr);
+            } else {
+                IntPtr certPtr, dataPtr;
+                certPtr = x509Cert.ToPointers(out dataPtr);
+                ret = NativeMethods.git_transport_smart_certificate_check(Transport, certPtr, valid ? 1 : 0, hostname);
+                Marshal.FreeHGlobal(dataPtr);
+                Marshal.FreeHGlobal(certPtr);
+            }
+
+            return ret;
+        }
+
+        public int AcquireCredentials(out Credentials cred, string user, params Type[] methods)
+        {
+            // Convert the user-provided types to libgit2's flags
+            int allowed = 0;
+            foreach (var method in methods)
+            {
+                if (method == typeof(UsernamePasswordCredentials))
+                {
+                    allowed |= (int)GitCredentialType.UserPassPlaintext;
+                }
+                else
+                {
+                    throw new InvalidOperationException("Unknown type passes as allowed credential");
+                }
+            }
+
+            IntPtr credHandle = IntPtr.Zero;
+            int res = Proxy.git_transport_smart_credentials(out credHandle, Transport, user, allowed);
+            if (res != 0)
+            {
+                cred = null;
+                return res;
+            }
+
+            var baseCred = credHandle.MarshalAs<GitCredential>();
+            switch (baseCred.credtype)
+            {
+                case GitCredentialType.UserPassPlaintext:
+                    cred = UsernamePasswordCredentials.FromNative(credHandle.MarshalAs<GitCredentialUserpass>());
+                    return 0;
+                default:
+                    throw new InvalidOperationException("User returned an unkown credential type");
+            }
+        }
+
         /// <summary>
         /// Invoked by libgit2 to create a connection using this subtransport.
         /// </summary>

LibGit2Sharp/SmartSubtransportRegistration.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Runtime.InteropServices;
 using LibGit2Sharp.Core;
+using LibGit2Sharp.Core.Handles;
 
 namespace LibGit2Sharp
 {
@@ -75,7 +76,9 @@ private static int Subtransport(
 
                 try
                 {
-                    subtransport = new T().GitSmartSubtransportPointer;
+                    var obj = new T();
+                    obj.Transport = transport;
+                    subtransport = obj.GitSmartSubtransportPointer;
 
                     return 0;
                 }