Log agent version over SSH

"agent" is a supported capability in the Git wire protocol, so we can
log Git user versions. If the parameter is not supplied, it will not
be listed as the final output in the sshd_log format.

Change-Id: Id953696f1e48a27c9b837e27972337090f8c7e9d

gerrit-sshd/src/main/java/com/google/gerrit/sshd/CommandFactoryProvider.java

@@ -217,7 +217,7 @@ class CommandFactoryProvider implements Provider<CommandFactory>,
 
     private void log(final int rc) {
       if (logged.compareAndSet(false, true)) {
-        log.onExecute(cmd, rc);
+        log.onExecute(cmd, rc, ctx.getSession());
       }
     }
 

gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshLog.java

@@ -47,6 +47,7 @@ class SshLog implements LifecycleListener {
   private static final String P_WAIT = "queueWaitTime";
   private static final String P_EXEC = "executionTime";
   private static final String P_STATUS = "status";
+  private static final String P_AGENT = "agent";
 
   private final Provider<SshSession> session;
   private final Provider<Context> context;
@@ -115,7 +116,7 @@ class SshLog implements LifecycleListener {
     audit(null, "FAIL", "AUTH");
   }
 
-  void onExecute(DispatchCommand dcmd, int exitValue) {
+  void onExecute(DispatchCommand dcmd, int exitValue, SshSession sshSession) {
     final Context ctx = context.get();
     ctx.finished = TimeUtil.nowMs();
 
@@ -144,6 +145,10 @@ class SshLog implements LifecycleListener {
         break;
     }
     event.setProperty(P_STATUS, status);
+    String peerAgent = sshSession.getPeerAgent();
+    if (peerAgent != null) {
+      event.setProperty(P_AGENT, peerAgent);
+    }
 
     if (async != null) {
       async.append(event);

gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshLogLayout.java

@@ -31,6 +31,7 @@ public final class SshLogLayout extends Layout {
   private static final String P_WAIT = "queueWaitTime";
   private static final String P_EXEC = "executionTime";
   private static final String P_STATUS = "status";
+  private static final String P_AGENT = "agent";
 
   private final Calendar calendar;
   private long lastTimeMillis;
@@ -66,6 +67,7 @@ public final class SshLogLayout extends Layout {
     opt(P_WAIT, buf, event);
     opt(P_EXEC, buf, event);
     opt(P_STATUS, buf, event);
+    opt(P_AGENT, buf, event);
 
     buf.append('\n');
     return buf.toString();

gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshSession.java

@@ -35,6 +35,7 @@ public class SshSession {
   private volatile CurrentUser identity;
   private volatile String username;
   private volatile String authError;
+  private volatile String peerAgent;
 
   SshSession(final int sessionId, SocketAddress peer) {
     this.sessionId = sessionId;
@@ -72,6 +73,14 @@ public class SshSession {
     return remoteAsString;
   }
 
+  public String getPeerAgent() {
+    return peerAgent;
+  }
+
+  public void setPeerAgent(String agent) {
+    peerAgent = agent;
+  }
+
   String getUsername() {
     return username;
   }

gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/Receive.java

@@ -22,6 +22,7 @@ import com.google.gerrit.server.git.ReceiveCommits;
 import com.google.gerrit.server.git.VisibleRefFilter;
 import com.google.gerrit.sshd.AbstractGitCommand;
 import com.google.gerrit.sshd.CommandMetaData;
+import com.google.gerrit.sshd.SshSession;
 import com.google.inject.Inject;
 
 import org.eclipse.jgit.errors.TooLargeObjectInPackException;
@@ -55,6 +56,9 @@ final class Receive extends AbstractGitCommand {
   @Inject
   private IdentifiedUser.GenericFactory identifiedUserFactory;
 
+  @Inject
+  private SshSession session;
+
   private final Set<Account.Id> reviewerId = new HashSet<>();
   private final Set<Account.Id> ccId = new HashSet<>();
 
@@ -91,6 +95,7 @@ final class Receive extends AbstractGitCommand {
     ReceivePack rp = receive.getReceivePack();
     try {
       rp.receive(in, out, err);
+      session.setPeerAgent(rp.getPeerUserAgent());
     } catch (UnpackException badStream) {
       // In case this was caused by the user pushing an object whose size
       // is larger than the receive.maxObjectSizeLimit gerrit.config parameter

gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/Upload.java

@@ -78,6 +78,7 @@ final class Upload extends AbstractGitCommand {
     up.setPreUploadHook(PreUploadHookChain.newChain(allPreUploadHooks));
     try {
       up.upload(in, out, err);
+      session.setPeerAgent(up.getPeerUserAgent());
     } catch (UploadValidationException e) {
       // UploadValidationException is used by the UploadValidators to
       // stop the uploadPack. We do not want this exception to go beyond this