sshd: correct the protocol version exchange

RFC 4253 section 4.2 allows an ssh server to send additional lines
before its server identification string. Apache MINA sshd enforces
for these lines the constraints specified for the server identification
line, too: no NUL characters and not longer than 255 characters. That
is too strict. RFC 4253 doesn't mandate this, and it also doesn't
make sense given the rationale for these lines in RFC 4253: a TCP
wrapper may not be aware of SSH restrictions, and may not adhere to
these constraints.

Be more lenient when parsing the server's protocol version. Allow
NULs and longer lines in the preamble, and also handle line endings
more leniently. Only enforce the restrictions for the actual server
identification line.

Bug: 545939
Change-Id: I75955e9d8a8daef7c04fc0f39539c2ee93514e1c
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

1 files changed, 18 insertions, 0 deletions

diff --git a/org.eclipse.jgit.junit.ssh/src/org/eclipse/jgit/junit/ssh/SshTestGitServer.java b/org.eclipse.jgit.junit.ssh/src/org/eclipse/jgit/junit/ssh/SshTestGitServer.java
index 25d952f189..7f155d4867 100644
--- a/org.eclipse.jgit.junit.ssh/src/org/eclipse/jgit/junit/ssh/SshTestGitServer.java
+++ b/org.eclipse.jgit.junit.ssh/src/org/eclipse/jgit/junit/ssh/SshTestGitServer.java
@@ -58,6 +58,7 @@ import java.util.Locale;
 
 import org.apache.sshd.common.NamedFactory;
 import org.apache.sshd.common.NamedResource;
+import org.apache.sshd.common.PropertyResolverUtils;
 import org.apache.sshd.common.SshConstants;
 import org.apache.sshd.common.config.keys.AuthorizedKeyEntry;
 import org.apache.sshd.common.config.keys.KeyUtils;
@@ -69,6 +70,7 @@ import org.apache.sshd.common.util.security.SecurityUtils;
 import org.apache.sshd.common.util.threads.CloseableExecutorService;
 import org.apache.sshd.common.util.threads.ThreadUtils;
 import org.apache.sshd.server.ServerAuthenticationManager;
+import org.apache.sshd.server.ServerFactoryManager;
 import org.apache.sshd.server.SshServer;
 import org.apache.sshd.server.auth.UserAuth;
 import org.apache.sshd.server.auth.gss.GSSAuthenticator;
@@ -342,6 +344,22 @@ public class SshTestGitServer {
 				.resolvePublicKey(null, PublicKeyEntryResolver.IGNORING);
 	}
 
+	/**
+	 * Sets the lines the server sends before its server identification in the
+	 * initial protocol version exchange.
+	 *
+	 * @param lines
+	 *            to send
+	 * @since 5.5
+	 */
+	public void setPreamble(String... lines) {
+		if (lines != null && lines.length > 0) {
+			PropertyResolverUtils.updateProperty(this.server,
+					ServerFactoryManager.SERVER_EXTRA_IDENTIFICATION_LINES,
+					String.join("|", lines));
+		}
+	}
+
 	private class GitUploadPackCommand extends AbstractCommandSupport {
 
 		protected GitUploadPackCommand(String command,