Fix SocketListener socket leak issue.

The problem was: if a socket is shared between SocketListener and another
thread, only if the last reference is removed by SocketListener can the socket
be closed, otherwise the socket will leak. This sometimes happens in netd's
dnsproxyd.

This change let the SocketClient own the socket and close the socket when
the SocketClient is destructed.

Change-Id: I2865fbfe9ee4d8b3e43d7e02919dbb2d261f70de

3 files changed, 16 insertions, 11 deletions

diff --git a/include/sysutils/SocketClient.h b/include/sysutils/SocketClient.h
index d6bb7d5..7d2b1d6 100644
--- a/include/sysutils/SocketClient.h
+++ b/include/sysutils/SocketClient.h
@@ -8,6 +8,7 @@
 
 class SocketClient {
     int             mSocket;
+    bool            mSocketOwned;
     pthread_mutex_t mWriteMutex;
 
     /* Peer process ID */
@@ -24,8 +25,8 @@ class SocketClient {
     int mRefCount;
 
 public:
-    SocketClient(int sock);
-    virtual ~SocketClient() {}
+    SocketClient(int sock, bool owned);
+    virtual ~SocketClient();
 
     int getSocket() { return mSocket; }
     pid_t getPid() const { return mPid; }
diff --git a/libsysutils/src/SocketClient.cpp b/libsysutils/src/SocketClient.cpp
index 90ca52e..722dcb2 100644
--- a/libsysutils/src/SocketClient.cpp
+++ b/libsysutils/src/SocketClient.cpp
@@ -10,8 +10,9 @@
 
 #include <sysutils/SocketClient.h>
 
-SocketClient::SocketClient(int socket)
+SocketClient::SocketClient(int socket, bool owned)
         : mSocket(socket)
+        , mSocketOwned(owned)
         , mPid(-1)
         , mUid(-1)
         , mGid(-1)
@@ -32,6 +33,13 @@ SocketClient::SocketClient(int socket)
     }
 }
 
+SocketClient::~SocketClient()
+{
+    if (mSocketOwned) {
+        close(mSocket);
+    }
+}
+
 int SocketClient::sendMsg(int code, const char *msg, bool addErrno) {
     char *buf;
     const char* arg;
diff --git a/libsysutils/src/SocketListener.cpp b/libsysutils/src/SocketListener.cpp
index fcad624..3f871ea 100644
--- a/libsysutils/src/SocketListener.cpp
+++ b/libsysutils/src/SocketListener.cpp
@@ -79,7 +79,7 @@ int SocketListener::startListener() {
         SLOGE("Unable to listen on socket (%s)", strerror(errno));
         return -1;
     } else if (!mListen)
-        mClients->push_back(new SocketClient(mSock));
+        mClients->push_back(new SocketClient(mSock, false));
 
     if (pipe(mCtrlPipe)) {
         SLOGE("pipe failed (%s)", strerror(errno));
@@ -191,7 +191,7 @@ void SocketListener::runListener() {
                 continue;
             }
             pthread_mutex_lock(&mClientsLock);
-            mClients->push_back(new SocketClient(c));
+            mClients->push_back(new SocketClient(c, true));
             pthread_mutex_unlock(&mClientsLock);
         }
 
@@ -225,12 +225,8 @@ void SocketListener::runListener() {
                     }
                 }
                 pthread_mutex_unlock(&mClientsLock);
-                /* Destroy the client */
-                int socket = c->getSocket();
-                if (c->decRef()) {
-                    // Note: 'c' is deleted memory at this point.
-                    close(socket);
-                }
+                /* Remove our reference to the client */
+                c->decRef();
             }
         }
     }