From ac941ffe6705ca2912c39ae484d15eeab403e5e7 Mon Sep 17 00:00:00 2001
From: IanHoar <hoar.ian@gmail.com>
Date: Thu, 11 Apr 2019 11:57:03 -0700
Subject: [PATCH 1/2] Fix non-thread-safe mutex access

When running SwiftWebSocket with the Thread Sanitizer, we noticed that there was a swift race condition when accessing the Manager's, or InnerWebSocket's mutex. Suspecting that this was simply a bug with the Thread Sanitizer we filed a Radar with Apple.  Their response was this was actually a true positive and directed us to this article: http://www.russbishop.net/the-law.

Because Swifts `&` might allow for mutation on multiple threads, we need to allocate our own memory for the mutex to avoid a heap corruption.
---
 Source/WebSocket.swift | 43 ++++++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 20 deletions(-)

diff --git a/Source/WebSocket.swift b/Source/WebSocket.swift
index 982e773..b513107 100644
--- a/Source/WebSocket.swift
+++ b/Source/WebSocket.swift
@@ -512,7 +512,7 @@ private class Deflater {
 /// WebSocket objects are bidirectional network streams that communicate over HTTP. RFC 6455.
 private class InnerWebSocket: Hashable {
     var id : Int
-    var mutex = pthread_mutex_t()
+    var mutex = UnsafeMutablePointer<pthread_mutex_t>.allocate(capacity: 1)
     let request : URLRequest!
     let subProtocols : [String]!
     var frames : [Frame] = []
@@ -607,7 +607,8 @@ private class InnerWebSocket: Hashable {
     }
 
     init(request: URLRequest, subProtocols : [String] = [], stub : Bool = false){
-        pthread_mutex_init(&mutex, nil)
+        mutex.initialize(to: pthread_mutex_t())
+        pthread_mutex_init(mutex, nil)
         self.id = manager.nextId()
         self.request = request
         self.subProtocols = subProtocols
@@ -633,13 +634,14 @@ private class InnerWebSocket: Hashable {
         if inputBytes != nil {
             free(inputBytes)
         }
-        pthread_mutex_init(&mutex, nil)
+        pthread_mutex_init(mutex, nil)
+        mutex.deallocate()
     }
     @inline(__always) fileprivate func lock(){
-        pthread_mutex_lock(&mutex)
+        pthread_mutex_lock(mutex)
     }
     @inline(__always) fileprivate func unlock(){
-        pthread_mutex_unlock(&mutex)
+        pthread_mutex_unlock(mutex)
     }
 
     fileprivate var dirty : Bool {
@@ -1570,35 +1572,36 @@ private enum TCPConnSecurity {
 private class Manager {
     var queue = DispatchQueue(label: "SwiftWebSocketInstance", attributes: [])
     var once = Int()
-    var mutex = pthread_mutex_t()
+    var mutex = UnsafeMutablePointer<pthread_mutex_t>.allocate(capacity: 1)
     var cond = pthread_cond_t()
     var websockets = Set<InnerWebSocket>()
     var _nextId = 0
     init(){
-        pthread_mutex_init(&mutex, nil)
+        mutex.initialize(to: pthread_mutex_t())
+        pthread_mutex_init(mutex, nil)
         pthread_cond_init(&cond, nil)
         DispatchQueue(label: "SwiftWebSocket", attributes: []).async {
             var wss : [InnerWebSocket] = []
             while true {
                 var wait = true
                 wss.removeAll()
-                pthread_mutex_lock(&self.mutex)
+                pthread_mutex_lock(self.mutex)
                 for ws in self.websockets {
                     wss.append(ws)
                 }
                 for ws in wss {
                     self.checkForConnectionTimeout(ws)
                     if ws.dirty {
-                        pthread_mutex_unlock(&self.mutex)
+                        pthread_mutex_unlock(self.mutex)
                         ws.step()
-                        pthread_mutex_lock(&self.mutex)
+                        pthread_mutex_lock(self.mutex)
                         wait = false
                     }
                 }
                 if wait {
                     _ = self.wait(250)
                 }
-                pthread_mutex_unlock(&self.mutex)
+                pthread_mutex_unlock(self.mutex)
             }
         }
     }
@@ -1620,28 +1623,28 @@ private class Manager {
         ts.tv_nsec = v1 + v2;
         ts.tv_sec += ts.tv_nsec / (1000 * 1000 * 1000);
         ts.tv_nsec %= (1000 * 1000 * 1000);
-        return pthread_cond_timedwait(&self.cond, &self.mutex, &ts)
+        return pthread_cond_timedwait(&self.cond, self.mutex, &ts)
     }
     func signal(){
-        pthread_mutex_lock(&mutex)
+        pthread_mutex_lock(mutex)
         pthread_cond_signal(&cond)
-        pthread_mutex_unlock(&mutex)
+        pthread_mutex_unlock(mutex)
     }
     func add(_ websocket: InnerWebSocket) {
-        pthread_mutex_lock(&mutex)
+        pthread_mutex_lock(mutex)
         websockets.insert(websocket)
         pthread_cond_signal(&cond)
-        pthread_mutex_unlock(&mutex)
+        pthread_mutex_unlock(mutex)
     }
     func remove(_ websocket: InnerWebSocket) {
-        pthread_mutex_lock(&mutex)
+        pthread_mutex_lock(mutex)
         websockets.remove(websocket)
         pthread_cond_signal(&cond)
-        pthread_mutex_unlock(&mutex)
+        pthread_mutex_unlock(mutex)
     }
     func nextId() -> Int {
-        pthread_mutex_lock(&mutex)
-        defer { pthread_mutex_unlock(&mutex) }
+        pthread_mutex_lock(mutex)
+        defer { pthread_mutex_unlock(mutex) }
         _nextId += 1
         return _nextId
     }

From 490fbc76ab46b7123357a94f42f332d2b149b625 Mon Sep 17 00:00:00 2001
From: IanHoar <hoar.ian@gmail.com>
Date: Thu, 11 Apr 2019 12:27:48 -0700
Subject: [PATCH 2/2] fixup! Fix non-thread-safe mutex access

---
 Source/WebSocket.swift | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Source/WebSocket.swift b/Source/WebSocket.swift
index b513107..04b5557 100644
--- a/Source/WebSocket.swift
+++ b/Source/WebSocket.swift
@@ -1605,6 +1605,10 @@ private class Manager {
             }
         }
     }
+    deinit{
+        pthread_mutex_init(mutex, nil)
+        mutex.deallocate()
+    }
     func checkForConnectionTimeout(_ ws : InnerWebSocket) {
         if ws.rd != nil && ws.wr != nil && (ws.rd.streamStatus == .opening || ws.wr.streamStatus == .opening) {
             let age = CFAbsoluteTimeGetCurrent() - ws.createdAt