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-rw-r--r--indra/llmessage/message.cpp41
-rw-r--r--indra/llmessage/message.h130
2 files changed, 150 insertions, 21 deletions
diff --git a/indra/llmessage/message.cpp b/indra/llmessage/message.cpp
index 6ef4025ab1..da62bb12e8 100644
--- a/indra/llmessage/message.cpp
+++ b/indra/llmessage/message.cpp
@@ -117,8 +117,8 @@ void LLMessageHandlerBridge::post(LLHTTPNode::ResponsePtr response,
gMessageSystem->mLastSender = LLHost(input["sender"].asString());
gMessageSystem->mPacketsIn += 1;
gMessageSystem->mLLSDMessageReader->setMessage(namePtr, input["body"]);
- gMessageSystem->mMessageReader = gMessageSystem->mLLSDMessageReader;
-
+ LockMessageReader rdr(gMessageSystem->mMessageReader, gMessageSystem->mLLSDMessageReader);
+
if(gMessageSystem->callHandler(namePtr, false, gMessageSystem))
{
response->result(LLSD());
@@ -189,7 +189,7 @@ void LLMessageSystem::init()
mTimingCallbackData = NULL;
mMessageBuilder = NULL;
- mMessageReader = NULL;
+ LockMessageReader(mMessageReader, NULL);
}
// Read file and build message templates
@@ -230,7 +230,6 @@ LLMessageSystem::LLMessageSystem(const std::string& filename, U32 port,
mTemplateMessageReader = new LLTemplateMessageReader(mMessageNumbers);
mLLSDMessageReader = new LLSDMessageReader();
- mMessageReader = NULL;
// initialize various bits of net info
mSocket = 0;
@@ -330,7 +329,6 @@ LLMessageSystem::~LLMessageSystem()
delete mTemplateMessageReader;
mTemplateMessageReader = NULL;
- mMessageReader = NULL;
delete mTemplateMessageBuilder;
mTemplateMessageBuilder = NULL;
@@ -480,11 +478,12 @@ LLCircuitData* LLMessageSystem::findCircuit(const LLHost& host,
}
// Returns TRUE if a valid, on-circuit message has been received.
-BOOL LLMessageSystem::checkMessages( S64 frame_count )
+// Requiring a non-const LockMessageChecker reference ensures that
+// mMessageReader has been set to mTemplateMessageReader.
+BOOL LLMessageSystem::checkMessages(LockMessageChecker&, S64 frame_count )
{
// Pump
BOOL valid_packet = FALSE;
- mMessageReader = mTemplateMessageReader;
LLTransferTargetVFile::updateQueue();
@@ -748,7 +747,7 @@ S32 LLMessageSystem::getReceiveBytes() const
}
-void LLMessageSystem::processAcks(F32 collect_time)
+void LLMessageSystem::processAcks(LockMessageChecker&, F32 collect_time)
{
F64Seconds mt_sec = getMessageTimeSeconds();
{
@@ -2062,8 +2061,9 @@ void LLMessageSystem::dispatch(
return;
}
// enable this for output of message names
- //LL_INFOS("Messaging") << "< \"" << msg_name << "\"" << LL_ENDL;
- //LL_DEBUGS() << "data: " << LLSDNotationStreamer(message) << LL_ENDL;
+ LL_DEBUGS("Messaging") << "< \"" << msg_name << "\"" << LL_ENDL;
+ LL_DEBUGS("Messaging") << "context: " << context << LL_ENDL;
+ LL_DEBUGS("Messaging") << "message: " << message << LL_ENDL;
handler->post(responsep, context, message);
}
@@ -3268,6 +3268,8 @@ void null_message_callback(LLMessageSystem *msg, void **data)
// up, and then sending auth messages.
void LLMessageSystem::establishBidirectionalTrust(const LLHost &host, S64 frame_count )
{
+ LockMessageChecker lmc(this);
+
std::string shared_secret = get_shared_secret();
if(shared_secret.empty())
{
@@ -3287,7 +3289,7 @@ void LLMessageSystem::establishBidirectionalTrust(const LLHost &host, S64 frame_
addU8Fast(_PREHASH_PingID, 0);
addU32Fast(_PREHASH_OldestUnacked, 0);
sendMessage(host);
- if (checkMessages( frame_count ))
+ if (lmc.checkMessages( frame_count ))
{
if (isMessageFast(_PREHASH_CompletePingCheck) &&
(getSender() == host))
@@ -3295,7 +3297,7 @@ void LLMessageSystem::establishBidirectionalTrust(const LLHost &host, S64 frame_
break;
}
}
- processAcks();
+ lmc.processAcks();
ms_sleep(1);
}
@@ -3314,8 +3316,8 @@ void LLMessageSystem::establishBidirectionalTrust(const LLHost &host, S64 frame_
cdp = mCircuitInfo.findCircuit(host);
if(!cdp) break; // no circuit anymore, no point continuing.
if(cdp->getTrusted()) break; // circuit is trusted.
- checkMessages(frame_count);
- processAcks();
+ lmc.checkMessages(frame_count);
+ lmc.processAcks();
ms_sleep(1);
}
}
@@ -3973,11 +3975,18 @@ void LLMessageSystem::setTimeDecodesSpamThreshold( F32 seconds )
LLMessageReader::setTimeDecodesSpamThreshold(seconds);
}
+LockMessageChecker::LockMessageChecker(LLMessageSystem* msgsystem):
+ // for the lifespan of this LockMessageChecker instance, use
+ // LLTemplateMessageReader as msgsystem's mMessageReader
+ LockMessageReader(msgsystem->mMessageReader, msgsystem->mTemplateMessageReader),
+ mMessageSystem(msgsystem)
+{}
+
// HACK! babbage: return true if message rxed via either UDP or HTTP
// TODO: babbage: move gServicePump in to LLMessageSystem?
-bool LLMessageSystem::checkAllMessages(S64 frame_count, LLPumpIO* http_pump)
+bool LLMessageSystem::checkAllMessages(LockMessageChecker& lmc, S64 frame_count, LLPumpIO* http_pump)
{
- if(checkMessages(frame_count))
+ if(lmc.checkMessages(frame_count))
{
return true;
}
diff --git a/indra/llmessage/message.h b/indra/llmessage/message.h
index 0af5a1b96d..a3f2829ece 100644
--- a/indra/llmessage/message.h
+++ b/indra/llmessage/message.h
@@ -61,6 +61,8 @@
#include "llstoredmessage.h"
#include "boost/function.hpp"
#include "llpounceable.h"
+#include "llcoros.h"
+#include LLCOROS_MUTEX_HEADER
const U32 MESSAGE_MAX_STRINGS_LENGTH = 64;
const U32 MESSAGE_NUMBER_OF_HASH_BUCKETS = 8192;
@@ -199,6 +201,89 @@ public:
virtual void complete(const LLHost& host, const LLUUID& agent) const = 0;
};
+/**
+ * SL-12204: We've observed crashes when consumer code sets
+ * LLMessageSystem::mMessageReader, assuming that all subsequent processing of
+ * the current message will use the same mMessageReader value -- only to have
+ * a different coroutine sneak in and replace mMessageReader before
+ * completion. This is a limitation of sharing a stateful global resource for
+ * message parsing; instead code receiving a new message should instantiate a
+ * (trivially constructed) local message parser and use that.
+ *
+ * Until then, when one coroutine sets a particular LLMessageReader subclass
+ * as the current message reader, ensure that no other coroutine can replace
+ * it until the first coroutine has finished with its message.
+ *
+ * This is achieved with two helper classes. LLMessageSystem::mMessageReader
+ * is now an LLMessageReaderPointer instance, which can efficiently compare or
+ * dereference its contained LLMessageReader* but which cannot be directly
+ * assigned. To change the value of LLMessageReaderPointer, you must
+ * instantiate LockMessageReader with the LLMessageReader* you wish to make
+ * current. mMessageReader will have that value for the lifetime of the
+ * LockMessageReader instance, then revert to nullptr. Moreover, as its name
+ * implies, LockMessageReader locks the mutex in LLMessageReaderPointer so
+ * that any other coroutine instantiating LockMessageReader will block until
+ * the first coroutine has destroyed its instance.
+ */
+class LLMessageReaderPointer
+{
+public:
+ LLMessageReaderPointer(): mPtr(nullptr) {}
+ // It is essential that comparison and dereferencing must be fast, which
+ // is why we don't check for nullptr when dereferencing.
+ LLMessageReader* operator->() const { return mPtr; }
+ bool operator==(const LLMessageReader* other) const { return mPtr == other; }
+ bool operator!=(const LLMessageReader* other) const { return ! (*this == other); }
+private:
+ // Only LockMessageReader can set mPtr.
+ friend class LockMessageReader;
+ LLMessageReader* mPtr;
+ LLCoros::Mutex mMutex;
+};
+
+/**
+ * To set mMessageReader to nullptr:
+ *
+ * @code
+ * // use an anonymous instance that is destroyed immediately
+ * LockMessageReader(gMessageSystem->mMessageReader, nullptr);
+ * @endcode
+ *
+ * Why do we still require going through LockMessageReader at all? Because it
+ * would be Bad if any coroutine set mMessageReader to nullptr while another
+ * coroutine was still parsing a message.
+ */
+class LockMessageReader
+{
+public:
+ // Because LockMessageReader contains LLCoros::LockType, it is already
+ // move-only. No need to delete the copy constructor or copy assignment.
+ LockMessageReader(LLMessageReaderPointer& var, LLMessageReader* instance):
+ mVar(var.mPtr),
+ mLock(var.mMutex)
+ {
+ mVar = instance;
+ }
+ ~LockMessageReader()
+ {
+ mVar = nullptr;
+ }
+private:
+ // capture a reference to LLMessageReaderPointer::mPtr
+ decltype(LLMessageReaderPointer::mPtr)& mVar;
+ // while holding a lock on LLMessageReaderPointer::mMutex
+ LLCoros::LockType mLock;
+};
+
+/**
+ * LockMessageReader is great as long as you only need mMessageReader locked
+ * during a single LLMessageSystem function call. However, empirically the
+ * sequence from checkAllMessages() through processAcks() need mMessageReader
+ * locked to LLTemplateMessageReader. Enforce that by making them require an
+ * instance of LockMessageChecker.
+ */
+class LockMessageChecker;
+
class LLMessageSystem : public LLMessageSenderInterface
{
private:
@@ -331,8 +416,8 @@ public:
bool addCircuitCode(U32 code, const LLUUID& session_id);
BOOL poll(F32 seconds); // Number of seconds that we want to block waiting for data, returns if data was received
- BOOL checkMessages( S64 frame_count = 0 );
- void processAcks(F32 collect_time = 0.f);
+ BOOL checkMessages(LockMessageChecker&, S64 frame_count = 0 );
+ void processAcks(LockMessageChecker&, F32 collect_time = 0.f);
BOOL isMessageFast(const char *msg);
BOOL isMessage(const char *msg)
@@ -730,7 +815,7 @@ public:
const LLSD& data);
// Check UDP messages and pump http_pump to receive HTTP messages.
- bool checkAllMessages(S64 frame_count, LLPumpIO* http_pump);
+ bool checkAllMessages(LockMessageChecker&, S64 frame_count, LLPumpIO* http_pump);
// Moved to allow access from LLTemplateMessageDispatcher
void clearReceiveState();
@@ -817,12 +902,13 @@ private:
LLMessageBuilder* mMessageBuilder;
LLTemplateMessageBuilder* mTemplateMessageBuilder;
LLSDMessageBuilder* mLLSDMessageBuilder;
- LLMessageReader* mMessageReader;
+ LLMessageReaderPointer mMessageReader;
LLTemplateMessageReader* mTemplateMessageReader;
LLSDMessageReader* mLLSDMessageReader;
friend class LLMessageHandlerBridge;
-
+ friend class LockMessageChecker;
+
bool callHandler(const char *name, bool trustedSource,
LLMessageSystem* msg);
@@ -835,6 +921,40 @@ private:
// external hook into messaging system
extern LLPounceable<LLMessageSystem*, LLPounceableStatic> gMessageSystem;
+// Implementation of LockMessageChecker depends on definition of
+// LLMessageSystem, hence must follow it.
+class LockMessageChecker: public LockMessageReader
+{
+public:
+ LockMessageChecker(LLMessageSystem* msgsystem);
+
+ // For convenience, provide forwarding wrappers so you can call (e.g.)
+ // checkAllMessages() on your LockMessageChecker instance instead of
+ // passing the instance to LLMessageSystem::checkAllMessages(). Use
+ // perfect forwarding to avoid having to maintain these wrappers in sync
+ // with the target methods.
+ template <typename... ARGS>
+ bool checkAllMessages(ARGS&&... args)
+ {
+ return mMessageSystem->checkAllMessages(*this, std::forward<ARGS>(args)...);
+ }
+
+ template <typename... ARGS>
+ bool checkMessages(ARGS&&... args)
+ {
+ return mMessageSystem->checkMessages(*this, std::forward<ARGS>(args)...);
+ }
+
+ template <typename... ARGS>
+ void processAcks(ARGS&&... args)
+ {
+ return mMessageSystem->processAcks(*this, std::forward<ARGS>(args)...);
+ }
+
+private:
+ LLMessageSystem* mMessageSystem;
+};
+
// Must specific overall system version, which is used to determine
// if a patch is available in the message template checksum verification.
// Return true if able to initialize system.
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-31 23:12:54 +0000