[FIXED JENKINS-44832] IAE under unknown conditions due to empty or nu…

…ll list of preferred key algorithms.
jenkinsci · Jun 13, 2017 · b9620ee · b9620ee
1 parent 9726126
commit b9620ee
Show file tree

Hide file tree

Showing 2 changed files with 14 additions and 1 deletion.
diff --git a/src/main/java/hudson/plugins/sshslaves/SSHLauncher.java b/src/main/java/hudson/plugins/sshslaves/SSHLauncher.java
@@ -793,7 +793,12 @@ public synchronized void launch(final SlaveComputer computer, final TaskListener
             public Boolean call() throws InterruptedException {
                 Boolean rval = Boolean.FALSE;
                 try {
-                    connection.setServerHostKeyAlgorithms(getSshHostKeyVerificationStrategyDefaulted().getPreferredKeyAlgorithms(computer));
+                    String[] preferredKeyAlgorithms = getSshHostKeyVerificationStrategyDefaulted().getPreferredKeyAlgorithms(computer);
+                    if (preferredKeyAlgorithms != null && preferredKeyAlgorithms.length > 0) { // JENKINS-44832
+                        connection.setServerHostKeyAlgorithms(preferredKeyAlgorithms);
+                    } else {
+                        listener.getLogger().println("Warning: no key algorithms provided; JENKINS-42959 disabled");
+                    }
 
                     openConnection(listener, computer);
 

diff --git a/src/main/java/hudson/plugins/sshslaves/verifiers/SshHostKeyVerificationStrategy.java b/src/main/java/hudson/plugins/sshslaves/verifiers/SshHostKeyVerificationStrategy.java
@@ -23,6 +23,8 @@
  */
 package hudson.plugins.sshslaves.verifiers;
 
+import com.trilead.ssh2.Connection;
+import edu.umd.cs.findbugs.annotations.CheckForNull;
 import hudson.model.Describable;
 import hudson.model.Descriptor;
 import hudson.model.TaskListener;
@@ -56,6 +58,12 @@ public SshHostKeyVerificationStrategyDescriptor getDescriptor() {
      */
     public abstract boolean verify(SlaveComputer computer, HostKey hostKey, TaskListener listener) throws Exception;
 
+    /**
+     * Provides a list of preferred key algorithms for this strategy and computer.
+     * @return a list of algorithms; empty or null lists will be ignored
+     * @see Connection#setServerHostKeyAlgorithms
+     */
+    @CheckForNull
     public String[] getPreferredKeyAlgorithms(SlaveComputer computer) throws IOException {
         return TrileadVersionSupportManager.getTrileadSupport().getSupportedAlgorithms();
     }