From 937f21d67c4382cf8fc140eab5cae57984308b15 Mon Sep 17 00:00:00 2001
From: Johannes Schmidt <johannes.schmidt@icinga.com>
Date: Wed, 2 Jul 2025 11:37:10 +0200
Subject: [PATCH] Detect client-side shutdown of TLS stream

---
 lib/remote/httpserverconnection.cpp | 29 ++++++++++++++++++++++++++++-
 lib/remote/httpserverconnection.hpp |  3 +++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/lib/remote/httpserverconnection.cpp b/lib/remote/httpserverconnection.cpp
index 617515822..f7320ca21 100644
--- a/lib/remote/httpserverconnection.cpp
+++ b/lib/remote/httpserverconnection.cpp
@@ -41,7 +41,7 @@ HttpServerConnection::HttpServerConnection(const WaitGroup::Ptr& waitGroup, cons
 }
 
 HttpServerConnection::HttpServerConnection(const WaitGroup::Ptr& waitGroup, const String& identity, bool authenticated, const Shared<AsioTlsStream>::Ptr& stream, boost::asio::io_context& io)
-	: m_WaitGroup(waitGroup), m_Stream(stream), m_Seen(Utility::GetTime()), m_IoStrand(io), m_ShuttingDown(false), m_HasStartedStreaming(false),
+	: m_WaitGroup(waitGroup), m_Stream(stream), m_Seen(Utility::GetTime()), m_CanRead(io, true), m_IoStrand(io), m_ShuttingDown(false), m_HasStartedStreaming(false),
 	m_CheckLivenessTimer(io)
 {
 	if (authenticated) {
@@ -66,6 +66,7 @@ void HttpServerConnection::Start()
 
 	IoEngine::SpawnCoroutine(m_IoStrand, [this, keepAlive](asio::yield_context yc) { ProcessMessages(yc); });
 	IoEngine::SpawnCoroutine(m_IoStrand, [this, keepAlive](asio::yield_context yc) { CheckLiveness(yc); });
+	IoEngine::SpawnCoroutine(m_IoStrand, [this, keepAlive](asio::yield_context yc) { DetectClientShutdown(yc); });
 }
 
 /**
@@ -446,6 +447,7 @@ void HttpServerConnection::ProcessMessages(boost::asio::yield_context yc)
 
 			response.set(http::field::server, l_ServerHeader);
 
+			m_CanRead.WaitForSet(yc);
 			if (!EnsureValidHeaders(buf, request, response, m_ShuttingDown, yc)) {
 				break;
 			}
@@ -504,6 +506,7 @@ void HttpServerConnection::ProcessMessages(boost::asio::yield_context yc)
 			}
 
 			m_Seen = std::numeric_limits<decltype(m_Seen)>::max();
+			m_CanRead.Clear();
 
 			if (!ProcessRequest(*m_Stream, request, response, *this, m_HasStartedStreaming, m_WaitGroup, cpuBoundWorkTime, yc)) {
 				break;
@@ -544,3 +547,27 @@ void HttpServerConnection::CheckLiveness(boost::asio::yield_context yc)
 		}
 	}
 }
+
+/**
+ * Detects a shutdown initiated by the client side.
+ *
+ * @param yc The yield context for the coroutine of this function
+ */
+void HttpServerConnection::DetectClientShutdown(boost::asio::yield_context yc)
+{
+	using wait_type = boost::asio::socket_base::wait_type;
+
+	while (!m_ShuttingDown) {
+		m_CanRead.WaitForClear(yc);
+
+		boost::system::error_code ec;
+		m_Stream->async_fill(yc[ec]);
+		if (ec && !m_ShuttingDown) {
+			Log(LogInformation, "HttpServerConnection") << "Detected shutdown from client: " << m_PeerAddress << ".";
+			Disconnect(yc);
+			break;
+		}
+
+		m_CanRead.Set();
+	}
+}
diff --git a/lib/remote/httpserverconnection.hpp b/lib/remote/httpserverconnection.hpp
index e4f7d257e..4af103ca7 100644
--- a/lib/remote/httpserverconnection.hpp
+++ b/lib/remote/httpserverconnection.hpp
@@ -4,6 +4,7 @@
 #define HTTPSERVERCONNECTION_H
 
 #include "remote/apiuser.hpp"
+#include "base/io-engine.hpp"
 #include "base/string.hpp"
 #include "base/tlsstream.hpp"
 #include "base/wait-group.hpp"
@@ -38,6 +39,7 @@ private:
 	ApiUser::Ptr m_ApiUser;
 	Shared<AsioTlsStream>::Ptr m_Stream;
 	double m_Seen;
+	AsioDualEvent m_CanRead;
 	String m_PeerAddress;
 	boost::asio::io_context::strand m_IoStrand;
 	bool m_ShuttingDown;
@@ -51,6 +53,7 @@ private:
 
 	void ProcessMessages(boost::asio::yield_context yc);
 	void CheckLiveness(boost::asio::yield_context yc);
+	void DetectClientShutdown(boost::asio::yield_context yc);
 };
 
 }