Prevent data loss when an ssl socket is closed by remote

SSL context was destroyed on disconnect. This makes it impossible to
decrypt buffered encrypted data. So if there is encrypted data in the
receive buffers, then don't destroy the ssl context until the socket is
destroyed.

Task-Number: QTBUG-23607
Change-Id: I16a7b4fa006647ec73049c90cdbc72686696850f
Reviewed-by: Jonas Gastal <jgastal@profusion.mobi>
Reviewed-by: Richard J. Moore <rich@kde.org>
(cherry picked from commit c5aba0ac17ae6ed8f3847bd30325acdbd1ecaa80)

2 files changed, 22 insertions, 13 deletions

diff --git a/src/network/ssl/qsslsocket_openssl.cpp b/src/network/ssl/qsslsocket_openssl.cpp
index 25d1d9e..5b1cd1b 100644
--- a/src/network/ssl/qsslsocket_openssl.cpp
+++ b/src/network/ssl/qsslsocket_openssl.cpp
@@ -183,6 +183,7 @@ QSslSocketBackendPrivate::QSslSocketBackendPrivate()
 
 QSslSocketBackendPrivate::~QSslSocketBackendPrivate()
 {
+    destroySslContext();
 }
 
 QSslCipher QSslSocketBackendPrivate::QSslCipher_from_SSL_CIPHER(SSL_CIPHER *cipher)
@@ -483,6 +484,22 @@ init_context:
     return true;
 }
 
+void QSslSocketBackendPrivate::destroySslContext()
+{
+    if (ssl) {
+        q_SSL_free(ssl);
+        ssl = 0;
+    }
+    if (ctx) {
+        q_SSL_CTX_free(ctx);
+        ctx = 0;
+    }
+    if (pkey) {
+        q_EVP_PKEY_free(pkey);
+        pkey = 0;
+    }
+}
+
 /*!
     \internal
 */
@@ -1403,19 +1420,10 @@ void QSslSocketBackendPrivate::disconnectFromHost()
 
 void QSslSocketBackendPrivate::disconnected()
 {
-    if (ssl) {
-        q_SSL_free(ssl);
-        ssl = 0;
-    }
-    if (ctx) {
-        q_SSL_CTX_free(ctx);
-        ctx = 0;
-    }
-    if (pkey) {
-        q_EVP_PKEY_free(pkey);
-        pkey = 0;
-    }
-
+    if (plainSocket->bytesAvailable() <= 0)
+        destroySslContext();
+    //if there is still buffered data in the plain socket, don't destroy the ssl context yet.
+    //it will be destroyed when the socket is deleted.
 }
 
 QSslCipher QSslSocketBackendPrivate::sessionCipher() const
diff --git a/src/network/ssl/qsslsocket_openssl_p.h b/src/network/ssl/qsslsocket_openssl_p.h
index bad2c9c..2940480 100644
--- a/src/network/ssl/qsslsocket_openssl_p.h
+++ b/src/network/ssl/qsslsocket_openssl_p.h
@@ -99,6 +99,7 @@ public:
 
     // SSL context
     bool initSslContext();
+    void destroySslContext();
     SSL *ssl;
     SSL_CTX *ctx;
     EVP_PKEY *pkey;