Handle HTTP port collisions when initializing server (#40)

10 files changed, 103 insertions, 56 deletions

diff --git a/zenhttp/httpasio.cpp b/zenhttp/httpasio.cpp
index 801bb51ac..f2d48200e 100644
--- a/zenhttp/httpasio.cpp
+++ b/zenhttp/httpasio.cpp
@@ -64,7 +64,7 @@ public:
 	HttpAsioServerImpl();
 	~HttpAsioServerImpl();
 
-	void		 Start(uint16_t Port, int ThreadCount);
+	int			 Start(uint16_t Port, int ThreadCount);
 	void		 Stop();
 	void		 RegisterService(const char* UrlPath, HttpService& Service);
 	HttpService* RouteRequest(std::string_view Url);
@@ -934,7 +934,12 @@ struct HttpAcceptor
 		m_Acceptor.set_option(asio::ip::v6_only(false));
 		m_Acceptor.set_option(asio::socket_base::reuse_address(true));
 		m_Acceptor.set_option(asio::ip::tcp::no_delay(true));
-		m_Acceptor.bind(asio::ip::tcp::endpoint(asio::ip::address_v6::any(), Port));
+		asio::error_code BindErrorCode;
+		m_Acceptor.bind(asio::ip::tcp::endpoint(asio::ip::address_v6::any(), Port), BindErrorCode);
+		if (BindErrorCode == asio::error::access_denied)
+		{
+			m_Acceptor.bind(asio::ip::tcp::endpoint(asio::ip::address_v6::any(), 0));
+		}
 		m_Acceptor.listen();
 	}
 
@@ -980,6 +985,8 @@ struct HttpAcceptor
 		});
 	}
 
+	int GetAcceptPort() { return m_Acceptor.local_endpoint().port(); }
+
 private:
 	HttpAsioServerImpl&		m_Server;
 	asio::io_service&		m_IoService;
@@ -1119,7 +1126,7 @@ HttpAsioServerImpl::~HttpAsioServerImpl()
 {
 }
 
-void
+int
 HttpAsioServerImpl::Start(uint16_t Port, int ThreadCount)
 {
 	ZEN_ASSERT(ThreadCount > 0);
@@ -1142,6 +1149,8 @@ HttpAsioServerImpl::Start(uint16_t Port, int ThreadCount)
 			}
 		});
 	}
+
+	return m_Acceptor->GetAcceptPort();
 }
 
 void
@@ -1212,12 +1221,11 @@ HttpAsioServer::RegisterService(HttpService& Service)
 	m_Impl->RegisterService(Service.BaseUri(), Service);
 }
 
-void
+int
 HttpAsioServer::Initialize(int BasePort)
 {
-	m_BasePort = BasePort;
-
-	m_Impl->Start(gsl::narrow<uint16_t>(m_BasePort), Max(std::thread::hardware_concurrency(), 8u));
+	m_BasePort = m_Impl->Start(gsl::narrow<uint16_t>(BasePort), Max(std::thread::hardware_concurrency(), 8u));
+	return m_BasePort;
 }
 
 void
diff --git a/zenhttp/httpasio.h b/zenhttp/httpasio.h
index 08834ba21..716145955 100644
--- a/zenhttp/httpasio.h
+++ b/zenhttp/httpasio.h
@@ -22,7 +22,7 @@ public:
 	~HttpAsioServer();
 
 	virtual void RegisterService(HttpService& Service) override;
-	virtual void Initialize(int BasePort) override;
+	virtual int	 Initialize(int BasePort) override;
 	virtual void Run(bool IsInteractiveSession) override;
 	virtual void RequestExit() override;
 
diff --git a/zenhttp/httpnull.cpp b/zenhttp/httpnull.cpp
index 31b13a6ce..a6e1d3567 100644
--- a/zenhttp/httpnull.cpp
+++ b/zenhttp/httpnull.cpp
@@ -24,10 +24,10 @@ HttpNullServer::RegisterService(HttpService& Service)
 	ZEN_UNUSED(Service);
 }
 
-void
+int
 HttpNullServer::Initialize(int BasePort)
 {
-	ZEN_UNUSED(BasePort);
+	return BasePort;
 }
 
 void
diff --git a/zenhttp/httpnull.h b/zenhttp/httpnull.h
index 867bbe4d2..74f021f6b 100644
--- a/zenhttp/httpnull.h
+++ b/zenhttp/httpnull.h
@@ -18,7 +18,7 @@ public:
 	~HttpNullServer();
 
 	virtual void RegisterService(HttpService& Service) override;
-	virtual void Initialize(int BasePort) override;
+	virtual int	 Initialize(int BasePort) override;
 	virtual void Run(bool IsInteractiveSession) override;
 	virtual void RequestExit() override;
 
diff --git a/zenhttp/httpsys.cpp b/zenhttp/httpsys.cpp
index b3d109b6a..3c57f7ce3 100644
--- a/zenhttp/httpsys.cpp
+++ b/zenhttp/httpsys.cpp
@@ -746,7 +746,7 @@ HttpSysServer::~HttpSysServer()
 	}
 }
 
-void
+int
 HttpSysServer::InitializeServer(int BasePort)
 {
 	using namespace std::literals;
@@ -762,7 +762,7 @@ HttpSysServer::InitializeServer(int BasePort)
 	{
 		ZEN_ERROR("Failed to create server session for '{}': {:#x}", WideToUtf8(WildcardUrlPath), Result);
 
-		return;
+		return BasePort;
 	}
 
 	Result = HttpCreateUrlGroup(m_HttpSessionId, &m_HttpUrlGroupId, 0);
@@ -771,17 +771,29 @@ HttpSysServer::InitializeServer(int BasePort)
 	{
 		ZEN_ERROR("Failed to create URL group for '{}': {:#x}", WideToUtf8(WildcardUrlPath), Result);
 
-		return;
+		return BasePort;
 	}
 
+	int EffectivePort = BasePort;
+
 	Result = HttpAddUrlToUrlGroup(m_HttpUrlGroupId, WildcardUrlPath.c_str(), HTTP_URL_CONTEXT(0), 0);
 
+	// Sharing violation implies the port is being used by another process
+	for (int PortOffset = 1; (Result == ERROR_SHARING_VIOLATION) && (PortOffset < 10); ++PortOffset)
+	{
+		EffectivePort = BasePort + (PortOffset * 100);
+		WildcardUrlPath.Reset();
+		WildcardUrlPath << u8"http://*:"sv << int64_t(EffectivePort) << u8"/"sv;
+
+		Result = HttpAddUrlToUrlGroup(m_HttpUrlGroupId, WildcardUrlPath.c_str(), HTTP_URL_CONTEXT(0), 0);
+	}
+
 	m_BaseUris.clear();
 	if (Result == NO_ERROR)
 	{
 		m_BaseUris.push_back(WildcardUrlPath.c_str());
 	}
-	else
+	else if (Result == ERROR_ACCESS_DENIED)
 	{
 		// If we can't register the wildcard path, we fall back to local paths
 		// This local paths allow requests originating locally to function, but will not allow
@@ -792,14 +804,26 @@ HttpSysServer::InitializeServer(int BasePort)
 
 		const std::u8string_view Hosts[] = {u8"[::1]"sv, u8"localhost"sv, u8"127.0.0.1"sv};
 
-		for (const std::u8string_view Host : Hosts)
+		ULONG InternalResult = ERROR_SHARING_VIOLATION;
+		for (int PortOffset = 0; (InternalResult == ERROR_SHARING_VIOLATION) && (PortOffset < 10); ++PortOffset)
 		{
-			WideStringBuilder<64> LocalUrlPath;
-			LocalUrlPath << u8"http://"sv << Host << u8":"sv << int64_t(BasePort) << u8"/"sv;
+			EffectivePort = BasePort + (PortOffset * 100);
 
-			if (HttpAddUrlToUrlGroup(m_HttpUrlGroupId, LocalUrlPath.c_str(), HTTP_URL_CONTEXT(0), 0) == NO_ERROR)
+			for (const std::u8string_view Host : Hosts)
 			{
-				m_BaseUris.push_back(LocalUrlPath.c_str());
+				WideStringBuilder<64> LocalUrlPath;
+				LocalUrlPath << u8"http://"sv << Host << u8":"sv << int64_t(EffectivePort) << u8"/"sv;
+
+				InternalResult = HttpAddUrlToUrlGroup(m_HttpUrlGroupId, LocalUrlPath.c_str(), HTTP_URL_CONTEXT(0), 0);
+
+				if (InternalResult == NO_ERROR)
+				{
+					m_BaseUris.push_back(LocalUrlPath.c_str());
+				}
+				else
+				{
+					break;
+				}
 			}
 		}
 	}
@@ -808,7 +832,7 @@ HttpSysServer::InitializeServer(int BasePort)
 	{
 		ZEN_ERROR("Failed to add base URL to URL group for '{}': {:#x}", WideToUtf8(WildcardUrlPath), Result);
 
-		return;
+		return BasePort;
 	}
 
 	HTTP_BINDING_INFO HttpBindingInfo = {{0}, 0};
@@ -823,7 +847,7 @@ HttpSysServer::InitializeServer(int BasePort)
 	{
 		ZEN_ERROR("Failed to create request queue for '{}': {:#x}", WideToUtf8(m_BaseUris.front()), Result);
 
-		return;
+		return EffectivePort;
 	}
 
 	HttpBindingInfo.Flags.Present	   = 1;
@@ -835,7 +859,7 @@ HttpSysServer::InitializeServer(int BasePort)
 	{
 		ZEN_ERROR("Failed to set server binding property for '{}': {:#x}", WideToUtf8(m_BaseUris.front()), Result);
 
-		return;
+		return EffectivePort;
 	}
 
 	// Create I/O completion port
@@ -853,6 +877,8 @@ HttpSysServer::InitializeServer(int BasePort)
 
 		ZEN_INFO("Started http.sys server at '{}'", WideToUtf8(m_BaseUris.front()));
 	}
+
+	return EffectivePort;
 }
 
 void
@@ -1603,11 +1629,12 @@ InitialRequestHandler::HandleCompletion(ULONG IoResult, ULONG_PTR NumberOfBytesT
 // HttpServer interface implementation
 //
 
-void
+int
 HttpSysServer::Initialize(int BasePort)
 {
-	InitializeServer(BasePort);
+	int EffectivePort = InitializeServer(BasePort);
 	StartServer();
+	return EffectivePort;
 }
 
 void
diff --git a/zenhttp/httpsys.h b/zenhttp/httpsys.h
index 06bad99c3..0453b8740 100644
--- a/zenhttp/httpsys.h
+++ b/zenhttp/httpsys.h
@@ -41,7 +41,7 @@ public:
 
 	// HttpServer interface implementation
 
-	virtual void Initialize(int BasePort) override;
+	virtual int	 Initialize(int BasePort) override;
 	virtual void Run(bool TestMode) override;
 	virtual void RequestExit() override;
 	virtual void RegisterService(HttpService& Service) override;
@@ -52,7 +52,7 @@ public:
 	inline bool IsAsyncResponseEnabled() const { return m_IsAsyncResponseEnabled; }
 
 private:
-	void InitializeServer(int BasePort);
+	int	 InitializeServer(int BasePort);
 	void Cleanup();
 
 	void StartServer();
diff --git a/zenhttp/include/zenhttp/httpserver.h b/zenhttp/include/zenhttp/httpserver.h
index 902310f04..545b96db2 100644
--- a/zenhttp/include/zenhttp/httpserver.h
+++ b/zenhttp/include/zenhttp/httpserver.h
@@ -169,7 +169,7 @@ class HttpServer : public RefCounted
 {
 public:
 	virtual void RegisterService(HttpService& Service) = 0;
-	virtual void Initialize(int BasePort)			   = 0;
+	virtual int	 Initialize(int BasePort)			   = 0;
 	virtual void Run(bool IsInteractiveSession)		   = 0;
 	virtual void RequestExit()						   = 0;
 };
diff --git a/zenserver/zenserver.cpp b/zenserver/zenserver.cpp
index 6a42a4044..c6a27ec44 100644
--- a/zenserver/zenserver.cpp
+++ b/zenserver/zenserver.cpp
@@ -155,7 +155,7 @@ namespace utils {
 class ZenServer : public IHttpStatusProvider
 {
 public:
-	void Initialize(const ZenServerOptions& ServerOptions, ZenServerState::ZenServerEntry* ServerEntry)
+	int Initialize(const ZenServerOptions& ServerOptions, ZenServerState::ZenServerEntry* ServerEntry)
 	{
 		m_UseSentry				 = ServerOptions.NoSentry == false;
 		m_ServerEntry			 = ServerEntry;
@@ -200,8 +200,8 @@ public:
 
 		// Ok so now we're configured, let's kick things off
 
-		m_Http = zen::CreateHttpServer(ServerOptions.HttpServerClass);
-		m_Http->Initialize(ServerOptions.BasePort);
+		m_Http				  = zen::CreateHttpServer(ServerOptions.HttpServerClass);
+		int EffectiveBasePort = m_Http->Initialize(ServerOptions.BasePort);
 
 		m_AuthService = std::make_unique<zen::HttpAuthService>();
 		m_Http->RegisterService(*m_AuthService);
@@ -262,7 +262,7 @@ public:
 #if ZEN_ENABLE_MESH
 		if (ServerOptions.MeshEnabled)
 		{
-			StartMesh(BasePort);
+			StartMesh(EffectiveBasePort);
 		}
 		else
 		{
@@ -309,6 +309,8 @@ public:
 			.Enabled			 = ServerOptions.GcConfig.Enabled,
 		};
 		m_GcScheduler.Initialize(GcConfig);
+
+		return EffectiveBasePort;
 	}
 
 	void InitializeState(const ZenServerOptions& ServerOptions);
@@ -889,6 +891,20 @@ ZenEntryPoint::Run()
 			Entry->AddSponsorProcess(ServerOptions.OwnerPid);
 		}
 
+		ZenServer Server;
+		Server.SetDataRoot(ServerOptions.DataDir);
+		Server.SetContentRoot(ServerOptions.ContentDir);
+		Server.SetTestMode(ServerOptions.IsTest);
+		Server.SetDedicatedMode(ServerOptions.IsDedicated);
+		int EffectiveBasePort = Server.Initialize(ServerOptions, Entry);
+
+		Entry->EffectiveListenPort = uint16_t(EffectiveBasePort);
+		if (EffectiveBasePort != ServerOptions.BasePort)
+		{
+			ZEN_INFO(ZEN_APP_NAME " - relocated to base port {}", EffectiveBasePort);
+			ServerOptions.BasePort = EffectiveBasePort;
+		}
+
 		std::unique_ptr<std::thread>	 ShutdownThread;
 		std::unique_ptr<zen::NamedEvent> ShutdownEvent;
 
@@ -896,13 +912,6 @@ ZenEntryPoint::Run()
 		ShutdownEventName << "Zen_" << ServerOptions.BasePort << "_Shutdown";
 		ShutdownEvent.reset(new zen::NamedEvent{ShutdownEventName});
 
-		ZenServer Server;
-		Server.SetDataRoot(ServerOptions.DataDir);
-		Server.SetContentRoot(ServerOptions.ContentDir);
-		Server.SetTestMode(ServerOptions.IsTest);
-		Server.SetDedicatedMode(ServerOptions.IsDedicated);
-		Server.Initialize(ServerOptions, Entry);
-
 		// Monitor shutdown signals
 
 		ShutdownThread.reset(new std::thread{[&] {
diff --git a/zenutil/include/zenutil/zenserverprocess.h b/zenutil/include/zenutil/zenserverprocess.h
index 55b9a50cd..2a3146e2d 100644
--- a/zenutil/include/zenutil/zenserverprocess.h
+++ b/zenutil/include/zenutil/zenserverprocess.h
@@ -100,11 +100,12 @@ public:
 		//       additional state. For example, you can use the session ID
 		//       to introduce additional named objects
 		std::atomic<uint32_t> Pid;
-		std::atomic<uint16_t> ListenPort;
+		std::atomic<uint16_t> DesiredListenPort;
 		std::atomic<uint16_t> Flags;
 		uint8_t				  SessionId[12];
 		std::atomic<uint32_t> SponsorPids[8];
-		uint8_t				  Padding[12];
+		std::atomic<uint16_t> EffectiveListenPort;
+		uint8_t				  Padding[10];
 
 		enum class FlagsEnum : uint16_t
 		{
@@ -125,8 +126,8 @@ public:
 
 	void						  Initialize();
 	[[nodiscard]] bool			  InitializeReadOnly();
-	[[nodiscard]] ZenServerEntry* Lookup(int ListenPort);
-	ZenServerEntry*				  Register(int ListenPort);
+	[[nodiscard]] ZenServerEntry* Lookup(int DesiredListenPort);
+	ZenServerEntry*				  Register(int DesiredListenPort);
 	void						  Sweep();
 	void						  Snapshot(std::function<void(const ZenServerEntry&)>&& Callback);
 	inline bool					  IsReadOnly() const { return m_IsReadOnly; }
diff --git a/zenutil/zenserverprocess.cpp b/zenutil/zenserverprocess.cpp
index fe6236d18..5bddc72bc 100644
--- a/zenutil/zenserverprocess.cpp
+++ b/zenutil/zenserverprocess.cpp
@@ -230,11 +230,11 @@ ZenServerState::InitializeReadOnly()
 }
 
 ZenServerState::ZenServerEntry*
-ZenServerState::Lookup(int ListenPort)
+ZenServerState::Lookup(int DesiredListenPort)
 {
 	for (int i = 0; i < m_MaxEntryCount; ++i)
 	{
-		if (m_Data[i].ListenPort == ListenPort)
+		if (m_Data[i].DesiredListenPort == DesiredListenPort)
 		{
 			return &m_Data[i];
 		}
@@ -244,7 +244,7 @@ ZenServerState::Lookup(int ListenPort)
 }
 
 ZenServerState::ZenServerEntry*
-ZenServerState::Register(int ListenPort)
+ZenServerState::Register(int DesiredListenPort)
 {
 	if (m_Data == nullptr)
 	{
@@ -259,17 +259,18 @@ ZenServerState::Register(int ListenPort)
 	{
 		ZenServerEntry& Entry = m_Data[i];
 
-		if (Entry.ListenPort.load(std::memory_order_relaxed) == 0)
+		if (Entry.DesiredListenPort.load(std::memory_order_relaxed) == 0)
 		{
 			uint16_t Expected = 0;
-			if (Entry.ListenPort.compare_exchange_strong(Expected, uint16_t(ListenPort)))
+			if (Entry.DesiredListenPort.compare_exchange_strong(Expected, uint16_t(DesiredListenPort)))
 			{
 				// Successfully allocated entry
 
 				m_OurEntry = &Entry;
 
-				Entry.Pid	= Pid;
-				Entry.Flags = 0;
+				Entry.Pid				  = Pid;
+				Entry.EffectiveListenPort = 0;
+				Entry.Flags				  = 0;
 
 				const Oid SesId = GetSessionId();
 				memcpy(Entry.SessionId, &SesId, sizeof SesId);
@@ -296,11 +297,11 @@ ZenServerState::Sweep()
 	{
 		ZenServerEntry& Entry = m_Data[i];
 
-		if (Entry.ListenPort)
+		if (Entry.DesiredListenPort)
 		{
 			if (IsProcessRunning(Entry.Pid) == false)
 			{
-				ZEN_DEBUG("Sweep - pid {} not running, reclaiming entry (port {})", Entry.Pid, Entry.ListenPort);
+				ZEN_DEBUG("Sweep - pid {} not running, reclaiming entry (port {})", Entry.Pid, Entry.DesiredListenPort);
 
 				Entry.Reset();
 			}
@@ -320,7 +321,7 @@ ZenServerState::Snapshot(std::function<void(const ZenServerEntry&)>&& Callback)
 	{
 		ZenServerEntry& Entry = m_Data[i];
 
-		if (Entry.ListenPort)
+		if (Entry.DesiredListenPort)
 		{
 			Callback(Entry);
 		}
@@ -330,9 +331,10 @@ ZenServerState::Snapshot(std::function<void(const ZenServerEntry&)>&& Callback)
 void
 ZenServerState::ZenServerEntry::Reset()
 {
-	Pid		   = 0;
-	ListenPort = 0;
-	Flags	   = 0;
+	Pid					= 0;
+	DesiredListenPort	= 0;
+	Flags				= 0;
+	EffectiveListenPort = 0;
 }
 
 void