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Fix race condition on SERVICE_ACCEPT (Fixes #559) (#560)

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This commit is contained in:
Jeroen van Erp
2020-02-25 13:33:38 +01:00
committed by GitHub
parent d09276fe01
commit f470ddf219
1 changed files with 15 additions and 7 deletions
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22
src/main/java/net/schmizz/sshj/transport/TransportImpl.java
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@@ -104,6 +104,11 @@ public final class TransportImpl
*/ */
private volatile Service service; private volatile Service service;
/**
* The next service that will be activated, only set when sending an SSH_MSG_SERVICE_REQUEST
*/
private volatile Service nextService;
private DisconnectListener disconnectListener; private DisconnectListener disconnectListener;
private ConnInfo connInfo; private ConnInfo connInfo;
@@ -324,8 +329,9 @@ public final class TransportImpl
@Override @Override
public synchronized void setService(Service service) { public synchronized void setService(Service service) {
if (service == null) if (service == null) {
service = nullService; service = nullService;
}
log.debug("Setting active service to {}", service.getName()); log.debug("Setting active service to {}", service.getName());
this.service = service; this.service = service;
@@ -337,11 +343,12 @@ public final class TransportImpl
serviceAccept.lock(); serviceAccept.lock();
try { try {
serviceAccept.clear(); serviceAccept.clear();
this.nextService = service;
sendServiceRequest(service.getName()); sendServiceRequest(service.getName());
serviceAccept.await(timeoutMs, TimeUnit.MILLISECONDS); serviceAccept.await(timeoutMs, TimeUnit.MILLISECONDS);
setService(service);
} finally { } finally {
serviceAccept.unlock(); serviceAccept.unlock();
this.nextService = null;
} }
} }
@@ -496,13 +503,11 @@ public final class TransportImpl
log.trace("Received packet {}", msg); log.trace("Received packet {}", msg);
if (msg.geq(50)) // not a transport layer packet if (msg.geq(50)) { // not a transport layer packet
service.handle(msg, buf); service.handle(msg, buf);
} else if (msg.in(20, 21) || msg.in(30, 49)) { // kex packet
else if (msg.in(20, 21) || msg.in(30, 49)) // kex packet
kexer.handle(msg, buf); kexer.handle(msg, buf);
} else {
else
switch (msg) { switch (msg) {
case DISCONNECT: case DISCONNECT:
gotDisconnect(buf); gotDisconnect(buf);
@@ -526,6 +531,7 @@ public final class TransportImpl
sendUnimplemented(); sendUnimplemented();
break; break;
} }
}
} }
private void gotDebug(SSHPacket buf) private void gotDebug(SSHPacket buf)
@@ -558,6 +564,8 @@ public final class TransportImpl
if (!serviceAccept.hasWaiters()) if (!serviceAccept.hasWaiters())
throw new TransportException(DisconnectReason.PROTOCOL_ERROR, throw new TransportException(DisconnectReason.PROTOCOL_ERROR,
"Got a service accept notification when none was awaited"); "Got a service accept notification when none was awaited");
// Immediately switch to next service to prevent race condition mentioned in #559
setService(nextService);
serviceAccept.set(); serviceAccept.set();
} finally { } finally {
serviceAccept.unlock(); serviceAccept.unlock();