From f702a64305a448336d5c50eb19a899f5d39dd6e0 Mon Sep 17 00:00:00 2001
From: server <server@jakubkadlec.dev>
Date: Tue, 14 Apr 2026 16:23:33 +0200
Subject: [PATCH] db: clarify peer disconnect diagnostics

---
 src/db/ClientManager.cpp  | 30 +++++++++++++++++++-----------
 src/db/PeerBase.cpp       |  5 ++++-
 src/libthecore/socket.cpp |  3 +++
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/src/db/ClientManager.cpp b/src/db/ClientManager.cpp
index 30c1431..4ce27a0 100644
--- a/src/db/ClientManager.cpp
+++ b/src/db/ClientManager.cpp
@@ -2500,7 +2500,8 @@ void CClientManager::ProcessPackets(CPeer * peer)
 				break;
 
 			default:					
-				sys_err("Unknown header (header: %d handle: %d length: %d)", header, dwHandle, dwLength);
+				sys_err("Unknown header (header=%u packet_handle=%u length=%u peer_handle=%u host=%s recv=%d processed=%d)",
+						header, dwHandle, dwLength, peer->GetHandle(), peer->GetHost(), peer->GetRecvLength(), i);
 				break;
 		}
 	}
@@ -2886,18 +2887,25 @@ int CClientManager::Process()
 		switch (fdwatch_check_event(m_fdWatcher, peer->GetFd(), idx))
 		{
 			case FDW_READ:
-				if (peer->Recv() < 0)
+				switch (peer->Recv())
 				{
-					sys_err("Recv failed");
-					RemovePeer(peer);
-				}
-				else
-				{
-					if (peer == m_pkAuthPeer)
-						if (g_log)
-							sys_log(0, "AUTH_PEER_READ: size %d", peer->GetRecvLength());
+					case -2:
+						sys_log(0, "Peer disconnected cleanly. (host=%s peer_handle=%u fd=%d)", peer->GetHost(), peer->GetHandle(), peer->GetFd());
+						RemovePeer(peer);
+						break;
 
-					ProcessPackets(peer);
+					case -1:
+						sys_err("Recv failed (host=%s peer_handle=%u fd=%d)", peer->GetHost(), peer->GetHandle(), peer->GetFd());
+						RemovePeer(peer);
+						break;
+
+					default:
+						if (peer == m_pkAuthPeer)
+							if (g_log)
+								sys_log(0, "AUTH_PEER_READ: size %d", peer->GetRecvLength());
+
+						ProcessPackets(peer);
+						break;
 				}
 				break;
 
diff --git a/src/db/PeerBase.cpp b/src/db/PeerBase.cpp
index 675799d..aeb7740 100644
--- a/src/db/PeerBase.cpp
+++ b/src/db/PeerBase.cpp
@@ -105,7 +105,10 @@ int CPeerBase::Recv()
 
 	if (bytes_read < 0)
 	{
-		sys_err("socket_read failed %s", strerror(errno));
+		if (errno == 0)
+			return -2;
+
+		sys_err("socket_read failed: host=%s fd=%d errno=%d (%s)", m_host, m_fd, errno, strerror(errno));
 		return -1;
 	}
 	else if (bytes_read == 0)
diff --git a/src/libthecore/socket.cpp b/src/libthecore/socket.cpp
index 4c070e9..4ab3261 100644
--- a/src/libthecore/socket.cpp
+++ b/src/libthecore/socket.cpp
@@ -45,7 +45,10 @@ int socket_read(socket_t desc, char* read_point, size_t space_left)
 	return ret;
 
     if (ret == 0)	// 정상적으로 접속 끊김
+    {
+	errno = 0;
 	return -1;
+    }
 
 #ifdef EINTR            /* Interrupted system call - various platforms */
     if (errno == EINTR)