Add cap-notify support

This change alone doesn’t notify any capabilities to clients, but makes
ZNC itself offer cap-notify and builds the foundations for various
notifiable capabilities, such as away-notify, can be easily added.

include/znc/Client.h

@@ -95,6 +95,7 @@ public:
 			  m_bGotNick(false),
 			  m_bGotUser(false),
 			  m_bInCap(false),
+			  m_bCapNotify(false),
 			  m_bNamesx(false),
 			  m_bUHNames(false),
 			  m_bAway(false),
@@ -111,12 +112,24 @@ public:
 			  m_sNetwork(""),
 			  m_sIdentifier(""),
 			  m_spAuth(),
-			  m_ssAcceptedCaps()
+			  m_ssAcceptedCaps(),
+			  m_mCoreCaps({{"multi-prefix", {false, [this](bool bVal) { m_bNamesx = bVal; }}},
+			               {"userhost-in-names", {false, [this](bool bVal) { m_bUHNames = bVal; }}},
+			               {"echo-message", {false, [this](bool bVal) { m_bEchoMessage = bVal; }}},
+			               {"server-time", {false, [this](bool bVal) { m_bServerTime = bVal; }}},
+			               {"batch", {false, [this](bool bVal) { m_bBatch = bVal; }}},
+			               {"cap-notify", {false, [this](bool bVal) { m_bCapNotify = bVal; }}},
+			              })
 	{
 		EnableReadLine();
 		// RFC says a line can have 512 chars max, but we are
 		// a little more gentle ;)
 		SetMaxBufferThreshold(1024);
+
+		// For compatibility with older clients
+		m_mCoreCaps["znc.in/server-time-iso"] = m_mCoreCaps["server-time"];
+		m_mCoreCaps["znc.in/batch"] = m_mCoreCaps["batch"];
+		m_mCoreCaps["znc.in/self-message"] = {false, [this](bool bVal) { m_bSelfMessage = bVal; }};
 	}
 
 	virtual ~CClient();
@@ -131,6 +144,7 @@ public:
 	CString GetNick(bool bAllowIRCNick = true) const;
 	CString GetNickMask() const;
 	CString GetIdentifier() const { return m_sIdentifier; }
+	bool HasCapNotify() const { return m_bCapNotify; }
 	bool HasNamesx() const { return m_bNamesx; }
 	bool HasUHNames() const { return m_bUHNames; }
 	bool IsAway() const { return m_bAway; }
@@ -160,6 +174,9 @@ public:
 
 	bool IsCapEnabled(const CString& sCap) const { return 1 == m_ssAcceptedCaps.count(sCap); }
 
+	void NotifyServerDependentCaps(const SCString& ssCaps);
+	void ClearServerDependentCaps();
+
 	void ReadLine(const CString& sData) override;
 	bool SendMotd();
 	void HelpUser(const CString& sFilter = "");
@@ -191,6 +208,7 @@ protected:
 	bool                 m_bGotNick;
 	bool                 m_bGotUser;
 	bool                 m_bInCap;
+	bool                 m_bCapNotify;
 	bool                 m_bNamesx;
 	bool                 m_bUHNames;
 	bool                 m_bAway;
@@ -208,6 +226,13 @@ protected:
 	CString              m_sIdentifier;
 	std::shared_ptr<CAuthBase> m_spAuth;
 	SCString             m_ssAcceptedCaps;
+	// The capabilities supported by the ZNC core - capability names mapped
+	// to a pair which contains a bool describing whether the capability is
+	// server-dependent, and a capability value change handler.
+	std::map<CString, std::pair<bool, std::function<void(bool bVal)>>> m_mCoreCaps;
+	// A subset of CIRCSock::GetAcceptedCaps(), the caps that can be listed
+	// in CAP LS and may be notified to the client with CAP NEW (cap-notify).
+	SCString             m_ssServerDependentCaps;
 
 	friend class ClientTest;
 };

include/znc/IRCSock.h

@@ -104,6 +104,7 @@ public:
 	const std::set<unsigned char>& GetUserModes() const { return m_scUserModes; }
 	// This is true if we are past raw 001
 	bool IsAuthed() const { return m_bAuthed; }
+	const SCString& GetAcceptedCaps() const { return m_ssAcceptedCaps; }
 	bool IsCapAccepted(const CString& sCap) { return 1 == m_ssAcceptedCaps.count(sCap); }
 	const MCString& GetISupport() const { return m_mISupport; }
 	CString GetISupport(const CString& sKey, const CString& sDefault = "") const;

src/Client.cpp

@@ -874,27 +874,20 @@ void CClient::HandleCap(const CString& sLine)
 	//TODO support ~ and = modifiers
 	CString sSubCmd = sLine.Token(1);
 
-	std::map<CString, std::function<void(bool bVal)>> mCoreCaps = {
-		{"multi-prefix", [this](bool bVal) { m_bNamesx = bVal; }},
-		{"userhost-in-names", [this](bool bVal) { m_bUHNames = bVal; }},
-		{"echo-message", [this](bool bVal) { m_bEchoMessage = bVal; }},
-		{"server-time", [this](bool bVal) { m_bServerTime = bVal; }},
-		{"batch", [this](bool bVal) { m_bBatch = bVal; }},
-	};
-	// For compatibility with older clients
-	mCoreCaps["znc.in/server-time-iso"] = mCoreCaps["server-time"];
-	mCoreCaps["znc.in/batch"] = mCoreCaps["batch"];
-	mCoreCaps["znc.in/self-message"] = [this](bool bVal) { m_bSelfMessage = bVal; };
-
 	if (sSubCmd.Equals("LS")) {
 		SCString ssOfferCaps;
-		for (const auto& it : mCoreCaps) {
-			ssOfferCaps.insert(it.first);
+		for (const auto& it : m_mCoreCaps) {
+			bool bServerDependent = std::get<0>(it.second);
+			if (!bServerDependent || m_ssServerDependentCaps.count(it.first) > 0)
+				ssOfferCaps.insert(it.first);
 		}
 		GLOBALMODULECALL(OnClientCapLs(this, ssOfferCaps), NOTHING);
 		CString sRes = CString(" ").Join(ssOfferCaps.begin(), ssOfferCaps.end());
 		RespondCap("LS :" + sRes);
 		m_bInCap = true;
+		if (sLine.Token(2).ToInt() >= 302) {
+			m_bCapNotify = true;
+		}
 	} else if (sSubCmd.Equals("END")) {
 		m_bInCap = false;
 		if (!IsAttached()) {
@@ -914,7 +907,12 @@ void CClient::HandleCap(const CString& sLine)
 			if (sCap.TrimPrefix("-"))
 				bVal = false;
 
-			bool bAccepted = mCoreCaps.count(sCap) > 0;
+			bool bAccepted = false;
+			const auto& it = m_mCoreCaps.find(sCap);
+			if (m_mCoreCaps.end() != it) {
+				bool bServerDependent = std::get<0>(it->second);
+				bAccepted = !bServerDependent || m_ssServerDependentCaps.count(sCap) > 0;
+			}
 			GLOBALMODULECALL(IsClientCapSupported(this, sCap, bVal), &bAccepted);
 
 			if (!bAccepted) {
@@ -931,9 +929,10 @@ void CClient::HandleCap(const CString& sLine)
 			if (sCap.TrimPrefix("-"))
 				bVal = false;
 
-			auto handler_it = mCoreCaps.find(sCap);
-			if (mCoreCaps.end() != handler_it) {
-				handler_it->second(bVal);
+			auto handler_it = m_mCoreCaps.find(sCap);
+			if (m_mCoreCaps.end() != handler_it) {
+				const auto& handler = std::get<1>(handler_it->second);
+				handler(bVal);
 			}
 			GLOBALMODULECALL(OnClientCapRequest(this, sCap, bVal), NOTHING);
 
@@ -996,3 +995,39 @@ void CClient::ParseIdentifier(const CString& sAuthLine) {
 		m_sUser = sAuthLine;
 	}
 }
+
+void CClient::NotifyServerDependentCaps(const SCString& ssCaps)
+{
+	for (const CString& sCap : ssCaps) {
+		const auto& it = m_mCoreCaps.find(sCap);
+		if (m_mCoreCaps.end() != it) {
+			bool bServerDependent = std::get<0>(it->second);
+			if (bServerDependent) {
+				m_ssServerDependentCaps.insert(sCap);
+			}
+		}
+	}
+
+	if (HasCapNotify() && !m_ssServerDependentCaps.empty()) {
+		CString sCaps = CString(" ").Join(m_ssServerDependentCaps.begin(), m_ssServerDependentCaps.end());
+		PutClient(":irc.znc.in CAP " + GetNick() + " NEW :" + sCaps);
+	}
+}
+
+void CClient::ClearServerDependentCaps()
+{
+	if (HasCapNotify() && !m_ssServerDependentCaps.empty()) {
+		CString sCaps = CString(" ").Join(m_ssServerDependentCaps.begin(), m_ssServerDependentCaps.end());
+		PutClient(":irc.znc.in CAP " + GetNick() + " DEL :" + sCaps);
+
+		for (const CString& sCap : m_ssServerDependentCaps) {
+			const auto& it = m_mCoreCaps.find(sCap);
+			if (m_mCoreCaps.end() != it) {
+				const auto& handler = std::get<1>(it->second);
+				handler(false);
+			}
+		}
+	}
+
+	m_ssServerDependentCaps.clear();
+}

src/IRCNetwork.cpp

@@ -567,6 +567,10 @@ void CIRCNetwork::ClientConnected(CClient *pClient) {
 
 	size_t uIdx, uSize;
 
+	if (m_pIRCSock) {
+		pClient->NotifyServerDependentCaps(m_pIRCSock->GetAcceptedCaps());
+	}
+
 	pClient->SetPlaybackActive(true);
 
 	if (m_RawBuffer.IsEmpty()) {
@@ -659,6 +663,7 @@ void CIRCNetwork::ClientDisconnected(CClient *pClient) {
 	if (it != m_vClients.end()) {
 		m_vClients.erase(it);
 	}
+	pClient->ClearServerDependentCaps();
 }
 
 CUser* CIRCNetwork::GetUser() const {
@@ -1223,6 +1228,10 @@ void CIRCNetwork::SetIRCSocket(CIRCSock* pIRCSock) {
 }
 
 void CIRCNetwork::IRCConnected() {
+	const SCString& ssCaps = m_pIRCSock->GetAcceptedCaps();
+	for (CClient* pClient : m_vClients) {
+		pClient->NotifyServerDependentCaps(ssCaps);
+	}
 	if (m_uJoinDelay > 0) {
 		m_pJoinTimer->Delay(m_uJoinDelay);
 	} else {
@@ -1231,6 +1240,9 @@ void CIRCNetwork::IRCConnected() {
 }
 
 void CIRCNetwork::IRCDisconnected() {
+	for (CClient* pClient : m_vClients) {
+		pClient->ClearServerDependentCaps();
+	}
 	m_pIRCSock = nullptr;
 
 	SetIRCServer("");