Dissolve gerrit-sshd top-level directory

Change-Id: Ie907bcd88fc30030883c0aa0705f8791cf2c3f6b

java/com/google/gerrit/sshd/HostKeyProvider.java

@@ -0,0 +1,87 @@
+// Copyright (C) 2009 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.sshd;
+
+import com.google.gerrit.server.config.SitePaths;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+import com.google.inject.ProvisionException;
+import java.io.File;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import org.apache.sshd.common.keyprovider.FileKeyPairProvider;
+import org.apache.sshd.common.keyprovider.KeyPairProvider;
+import org.apache.sshd.server.keyprovider.SimpleGeneratorHostKeyProvider;
+
+class HostKeyProvider implements Provider<KeyPairProvider> {
+  private final SitePaths site;
+
+  @Inject
+  HostKeyProvider(SitePaths site) {
+    this.site = site;
+  }
+
+  @Override
+  public KeyPairProvider get() {
+    Path objKey = site.ssh_key;
+    Path rsaKey = site.ssh_rsa;
+    Path dsaKey = site.ssh_dsa;
+    Path ecdsaKey_256 = site.ssh_ecdsa_256;
+    Path ecdsaKey_384 = site.ssh_ecdsa_384;
+    Path ecdsaKey_521 = site.ssh_ecdsa_521;
+    Path ed25519Key = site.ssh_ed25519;
+
+    final List<File> stdKeys = new ArrayList<>(6);
+    if (Files.exists(rsaKey)) {
+      stdKeys.add(rsaKey.toAbsolutePath().toFile());
+    }
+    if (Files.exists(dsaKey)) {
+      stdKeys.add(dsaKey.toAbsolutePath().toFile());
+    }
+    if (Files.exists(ecdsaKey_256)) {
+      stdKeys.add(ecdsaKey_256.toAbsolutePath().toFile());
+    }
+    if (Files.exists(ecdsaKey_384)) {
+      stdKeys.add(ecdsaKey_384.toAbsolutePath().toFile());
+    }
+    if (Files.exists(ecdsaKey_521)) {
+      stdKeys.add(ecdsaKey_521.toAbsolutePath().toFile());
+    }
+    if (Files.exists(ed25519Key)) {
+      stdKeys.add(ed25519Key.toAbsolutePath().toFile());
+    }
+
+    if (Files.exists(objKey)) {
+      if (stdKeys.isEmpty()) {
+        SimpleGeneratorHostKeyProvider p = new SimpleGeneratorHostKeyProvider();
+        p.setPath(objKey.toAbsolutePath());
+        return p;
+      }
+      // Both formats of host key exist, we don't know which format
+      // should be authoritative. Complain and abort.
+      //
+      stdKeys.add(objKey.toAbsolutePath().toFile());
+      throw new ProvisionException("Multiple host keys exist: " + stdKeys);
+    }
+    if (stdKeys.isEmpty()) {
+      throw new ProvisionException("No SSH keys under " + site.etc_dir);
+    }
+    FileKeyPairProvider kp = new FileKeyPairProvider();
+    kp.setFiles(stdKeys);
+    return kp;
+  }
+}