SSH: Act on failing SFTP server.

So far we ignored crashes and unexpected exits of the remote SFTP
service under the assumption that the SSH server would catch these
itself and act accordingly. This is not the case, however: OpenSSH,
for instance, does not even realize if its sftp-server binary is
not present at all. As a result, Qt Creator waits indefinitely for
an SFTP operation to finish. Now we emit an error and close the
offending channel.

Task-number: QTCREATORBUG-10339
Change-Id: I132ed4a0098434a4cfce6056b964bd6363951fd7
Reviewed-by: Volker Vogelhuber <[email protected]>
Reviewed-by: Christian Kandeler <[email protected]>

1 files changed, 15 insertions, 11 deletions

diff --git a/src/libs/ssh/sftpchannel.cpp b/src/libs/ssh/sftpchannel.cpp
index 39ba41bb668..b5e68b6e329 100644
--- a/src/libs/ssh/sftpchannel.cpp
+++ b/src/libs/ssh/sftpchannel.cpp
@@ -88,8 +88,8 @@ SftpChannel::SftpChannel(quint32 channelId,
 {
     connect(d, SIGNAL(initialized()), this, SIGNAL(initialized()),
         Qt::QueuedConnection);
-    connect(d, SIGNAL(initializationFailed(QString)), this,
-        SIGNAL(initializationFailed(QString)), Qt::QueuedConnection);
+    connect(d, SIGNAL(channelError(QString)), this,
+        SIGNAL(channelError(QString)), Qt::QueuedConnection);
     connect(d, SIGNAL(dataAvailable(QSsh::SftpJobId,QString)), this,
         SIGNAL(dataAvailable(QSsh::SftpJobId,QString)), Qt::QueuedConnection);
     connect(d, SIGNAL(fileInfoAvailable(QSsh::SftpJobId,QList<QSsh::SftpFileInfo>)), this,
@@ -271,7 +271,7 @@ void SftpChannelPrivate::handleChannelFailure()
         throw SSH_SERVER_EXCEPTION(SSH_DISCONNECT_PROTOCOL_ERROR,
             "Unexpected SSH_MSG_CHANNEL_FAILURE packet.");
     }
-    emit initializationFailed(tr("Server could not start SFTP subsystem."));
+    emit channelError(tr("Server could not start SFTP subsystem."));
     closeChannel();
 }
 
@@ -298,18 +298,22 @@ void SftpChannelPrivate::handleChannelExtendedDataInternal(quint32 type,
 
 void SftpChannelPrivate::handleExitStatus(const SshChannelExitStatus &exitStatus)
 {
-    const char * const message = "Remote SFTP service exited with exit code %d";
 #ifdef CREATOR_SSH_DEBUG
-    qDebug(message, exitStatus.exitStatus);
-#else
-    if (exitStatus.exitStatus != 0)
-        qWarning(message, exitStatus.exitStatus);
+    qDebug("Remote SFTP service exited with exit code %d", exitStatus.exitStatus);
 #endif
+
+    emit channelError(tr("The SFTP server finished unexpectedly with exit code %1.")
+                      .arg(exitStatus.exitStatus));
+
+    // Note: According to the specs, the server must close the channel after this happens,
+    // but OpenSSH doesn't do that, so we need to initiate the closing procedure ourselves.
+    closeChannel();
 }
 
 void SftpChannelPrivate::handleExitSignal(const SshChannelExitSignal &signal)
 {
-    qWarning("Remote SFTP service killed; signal was %s", signal.signal.data());
+    emit channelError(tr("The SFTP server crashed: %1.").arg(signal.error));
+    closeChannel(); // See above.
 }
 
 void SftpChannelPrivate::handleCurrentPacket()
@@ -356,7 +360,7 @@ void SftpChannelPrivate::handleServerVersion()
 #endif
     const quint32 serverVersion = m_incomingPacket.extractServerVersion();
     if (serverVersion != ProtocolVersion) {
-        emit initializationFailed(tr("Protocol version mismatch: Expected %1, got %2")
+        emit channelError(tr("Protocol version mismatch: Expected %1, got %2")
             .arg(serverVersion).arg(ProtocolVersion));
         closeChannel();
     } else {
@@ -854,7 +858,7 @@ void SftpChannelPrivate::handleOpenFailureInternal(const QString &reason)
         throw SSH_SERVER_EXCEPTION(SSH_DISCONNECT_PROTOCOL_ERROR,
             "Unexpected SSH_MSG_CHANNEL_OPEN_FAILURE packet.");
     }
-    emit initializationFailed(tr("Server could not start session: %1").arg(reason));
+    emit channelError(tr("Server could not start session: %1").arg(reason));
 }
 
 void SftpChannelPrivate::sendReadRequest(const SftpDownload::Ptr &job,