From 90560da5c35b71851fbea584e4afd0a5a5495540 Mon Sep 17 00:00:00 2001
From: Davide Beatrici <git@davidebeatrici.dev>
Date: Fri, 23 Feb 2024 23:57:22 +0100
Subject: [PATCH] Connection: Fix unexpected server disconnection due to
 OpenSSL thread safety problems

From the OpenSSL FAQ (https://www.openssl.org/docs/faq.html):

"... an SSL connection cannot be used concurrently by multiple threads. This is true for most OpenSSL objects."
---
 src/Connection.cpp | 7 +++++++
 src/Connection.hpp | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/src/Connection.cpp b/src/Connection.cpp
index 88211d5..e5e5402 100644
--- a/src/Connection.cpp
+++ b/src/Connection.cpp
@@ -35,6 +35,8 @@ Connection::operator bool() const {
 }
 
 Code Connection::operator()(const Feedback &feedback, const std::function< bool() > halt) {
+	const auto guard = m_p->lock();
+
 	if (!m_p->m_monitorIn.add(m_p->m_handle, true, false) || !m_p->m_monitorOut.add(m_p->m_handle, false, true)) {
 		return Code::Failure;
 	}
@@ -87,6 +89,8 @@ Cert::Chain Connection::peerCert() const {
 }
 
 bool Connection::setCert(const Cert::Chain &cert, const Key &key) {
+	const auto guard = m_p->lock();
+
 	return m_p->setCert(cert, key);
 }
 
@@ -94,6 +98,7 @@ Code Connection::process(const bool wait, const std::function< bool() > halt) {
 	using NetHeader = tcp::NetHeader;
 	using Pack      = tcp::Pack;
 
+	const auto guard = m_p->lock();
 	do {
 		NetHeader header;
 		auto code = m_p->read({ reinterpret_cast< std::byte * >(&header), sizeof(header) }, wait, halt);
@@ -123,6 +128,8 @@ Code Connection::process(const bool wait, const std::function< bool() > halt) {
 }
 
 Code Connection::write(const BufViewConst data, const bool wait, const std::function< bool() > halt) {
+	const auto guard = m_p->lock();
+
 	return m_p->write(data, wait, halt);
 }
 
diff --git a/src/Connection.hpp b/src/Connection.hpp
index e103f78..cbfc2aa 100644
--- a/src/Connection.hpp
+++ b/src/Connection.hpp
@@ -17,6 +17,7 @@
 #include <atomic>
 #include <cstdint>
 #include <functional>
+#include <mutex>
 
 namespace mumble {
 class Connection::P : public SocketTLS {
@@ -33,6 +34,10 @@ class Connection::P : public SocketTLS {
 	mumble::Code handleState(const State state);
 
 private:
+	[[nodiscard]] std::lock_guard< std::recursive_mutex > lock() {
+		return std::lock_guard< std::recursive_mutex >(m_mutex);
+	}
+
 	mumble::Code read(BufView buf, const bool wait, const std::function< bool() > halt);
 	mumble::Code write(BufViewConst buf, const bool wait, const std::function< bool() > halt);
 
@@ -49,6 +54,7 @@ class Connection::P : public SocketTLS {
 	Cert::Chain m_cert;
 	uint32_t m_timeouts;
 	std::atomic_flag m_closed;
+	std::recursive_mutex m_mutex;
 };
 } // namespace mumble