WebModules: Fix a crash during shutdown

During shutdown, the global list of sessions is destroyed. The new multimap
which counts sessions per address is also destroyed. However, they are destroyed
in unspecified order. This is not what we want because destructing the session
map also destroyed all the sessions which then has to access the sessions-per-ip
multimap. This obviously crashes if the multimap was already destroyed.

The fix here is to introduce a new class that contains both of those maps and
makes sure all the sessions are destroyed before the maps are destroyed
themselves. I hope this description makes some sense...


git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@2264 726aef4b-f618-498e-8847-2d620e286838

WebModules.cpp

@@ -14,23 +14,40 @@
 /// @todo Do we want to make this a configure option?
 #define _SKINDIR_ _DATADIR_ "/webskins"
 
-// Sessions are valid for a day, (24h, ...)
+const unsigned int CWebSock::m_uiMaxSessions = 5;
-CWebSessionMap CWebSock::m_mspSessions(24 * 60 * 60 * 1000);
+
-static std::multimap<CString, CWebSession*> mIPSessions;
+// We need this class to make sure the contained maps and their content is
+// destroyed in the order that we want.
+struct CSessionManager {
+	// Sessions are valid for a day, (24h, ...)
+	CSessionManager() : m_mspSessions(24 * 60 * 60 * 1000) {}
+	~CSessionManager() {
+		// Make sure all sessions are destroyed before any of our maps
+		// are destroyed
+		m_mspSessions.Clear();
+	}
+
+	CWebSessionMap m_mspSessions;
+	std::multimap<CString, CWebSession*> m_mIPSessions;
+};
 typedef std::multimap<CString, CWebSession*>::iterator mIPSessionsIterator;
 
-const unsigned int CWebSock::m_uiMaxSessions = 5;
+static CSessionManager Sessions;
+
+void CWebSock::FinishUserSessions(const CUser& User) {
+	Sessions.m_mspSessions.FinishUserSessions(User);
+}
 
 CWebSession::~CWebSession() {
 	// Find our entry in mIPSessions
 	pair<mIPSessionsIterator, mIPSessionsIterator> p =
-		mIPSessions.equal_range(m_sIP);
+		Sessions.m_mIPSessions.equal_range(m_sIP);
 	mIPSessionsIterator it = p.first;
 	mIPSessionsIterator end = p.second;
 
 	while (it != end) {
 		if (it->second == this) {
-			mIPSessions.erase(it++);
+			Sessions.m_mIPSessions.erase(it++);
 		} else {
 			++it;
 		}
@@ -52,7 +69,7 @@ bool CZNCTagHandler::HandleTag(CTemplate& Tmpl, const CString& sName, const CStr
 
 CWebSession::CWebSession(const CString& sId, const CString& sIP) : m_sId(sId), m_sIP(sIP) {
 	m_pUser = NULL;
-	mIPSessions.insert(make_pair(sIP, this));
+	Sessions.m_mIPSessions.insert(make_pair(sIP, this));
 }
 
 bool CWebSession::IsAdmin() const { return IsLoggedIn() && m_pUser->IsAdmin(); }
@@ -681,19 +698,19 @@ CSmartPtr<CWebSession> CWebSock::GetSession() {
 	}
 
 	const CString sCookieSessionId = GetRequestCookie("SessionId");
-	CSmartPtr<CWebSession> *pSession = m_mspSessions.GetItem(sCookieSessionId);
+	CSmartPtr<CWebSession> *pSession = Sessions.m_mspSessions.GetItem(sCookieSessionId);
 
 	if (pSession != NULL) {
 		// Refresh the timeout
-		m_mspSessions.AddItem((*pSession)->GetId(), *pSession);
+		Sessions.m_mspSessions.AddItem((*pSession)->GetId(), *pSession);
 		m_spSession = *pSession;
 		DEBUG("Found existing session from cookie: [" + sCookieSessionId + "] IsLoggedIn(" + CString((*pSession)->IsLoggedIn() ? "true" : "false") + ")");
 		return *pSession;
 	}
 
-	if (mIPSessions.count(GetRemoteIP()) > m_uiMaxSessions) {
+	if (Sessions.m_mIPSessions.count(GetRemoteIP()) > m_uiMaxSessions) {
-		mIPSessionsIterator it = mIPSessions.find(GetRemoteIP());
+		mIPSessionsIterator it = Sessions.m_mIPSessions.find(GetRemoteIP());
-		mIPSessions.erase(it);
+		Sessions.m_mIPSessions.erase(it);
 	}
 
 	CString sSessionID;
@@ -705,10 +722,10 @@ CSmartPtr<CWebSession> CWebSock::GetSession() {
 		sSessionID = sSessionID.SHA256();
 
 		DEBUG("Auto generated session: [" + sSessionID + "]");
-	} while (m_mspSessions.HasItem(sSessionID));
+	} while (Sessions.m_mspSessions.HasItem(sSessionID));
 
 	CSmartPtr<CWebSession> spSession(new CWebSession(sSessionID, GetRemoteIP()));
-	m_mspSessions.AddItem(spSession->GetId(), spSession);
+	Sessions.m_mspSessions.AddItem(spSession->GetId(), spSession);
 
 	m_spSession = spSession;
 

WebModules.h

@@ -147,9 +147,7 @@ public:
 	CString GetRequestCookie(const CString& sKey);
 	bool SendCookie(const CString& sKey, const CString& sValue);
 
-	static void FinishUserSessions(const CUser& User) {
+	static void FinishUserSessions(const CUser& User);
-		m_mspSessions.FinishUserSessions(User);
-	}
 
 protected:
 	using CHTTPSock::PrintErrorPage;
@@ -171,7 +169,6 @@ private:
 	CString                 m_sPage;        // Gets filled by ParsePath()
 	CSmartPtr<CWebSession>  m_spSession;
 
-	static CWebSessionMap   m_mspSessions;
 	static const unsigned int m_uiMaxSessions;
 };