Handle HTTP port collisions when initializing server (#40)

2 files changed, 20 insertions, 17 deletions

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