Log "-" for missing log fields in sshd_log

In order to simplify parsing sshd_log files emit a "-" placeholder if a
field is missing in a log record except for LOGIN and LOGOUT which only
log basic fields.

This is a preparation to allow appending new log fields in future Gerrit
versions without disrupting existing tools parsing the sshd_log.

Change-Id: I90adc7618864f702b42029ab596c6014bd4c6cfe

1 files changed, 8 insertions, 13 deletions

diff --git a/java/com/google/gerrit/sshd/SshLogLayout.java b/java/com/google/gerrit/sshd/SshLogLayout.java
index 1dda0686b8..0779cbe088 100644
--- a/java/com/google/gerrit/sshd/SshLogLayout.java
+++ b/java/com/google/gerrit/sshd/SshLogLayout.java
@@ -56,11 +56,14 @@ public final class SshLogLayout extends Layout {
     buf.append(' ');
     buf.append(event.getMessage());
 
-    opt(P_WAIT, buf, event);
-    opt(P_EXEC, buf, event);
-    opt(P_MESSAGE, buf, event);
-    opt(P_STATUS, buf, event);
-    opt(P_AGENT, buf, event);
+    String msg = (String) event.getMessage();
+    if (!(msg.startsWith("LOGIN") || msg.equals("LOGOUT"))) {
+      req(P_WAIT, buf, event);
+      req(P_EXEC, buf, event);
+      req(P_MESSAGE, buf, event);
+      req(P_STATUS, buf, event);
+      req(P_AGENT, buf, event);
+    }
 
     buf.append('\n');
     return buf.toString();
@@ -81,14 +84,6 @@ public final class SshLogLayout extends Layout {
     }
   }
 
-  private void opt(String key, StringBuffer buf, LoggingEvent event) {
-    Object val = event.getMDC(key);
-    if (val != null) {
-      buf.append(' ');
-      buf.append(val);
-    }
-  }
-
   @Override
   public boolean ignoresThrowable() {
     return true;