Disable zero copy when performing SSL handshake

Summary:
If zero copy starts out enabled on a unencrypted connection, disable
it when the SSL handshake begins. Otherwise, AsyncSocket will receive send
notifications for buffers that it did not pre-register.

Reviewed By: yfeldblum

Differential Revision: D27145232

fbshipit-source-id: f07d006d095e1e6839eb2f4adb07d7c284786572

folly/io/async/AsyncSSLSocket.cpp

@@ -514,6 +514,10 @@ void AsyncSSLSocket::sslAccept(
     cacheAddresses();
   }
 
+  // AsyncSSLSocket will leak memory if zero copy if left enabled after
+  // the TLS handshake
+  setZeroCopy(false);
+
   handshakeStartTime_ = std::chrono::steady_clock::now();
   // Make end time at least >= start time.
   handshakeEndTime_ = handshakeStartTime_;
@@ -865,6 +869,10 @@ void AsyncSSLSocket::sslConn(
     return failHandshake(__func__, *ex);
   }
 
+  // AsyncSSLSocket will leak memory if zero copy if left enabled after
+  // the TLS handshake
+  setZeroCopy(false);
+
   SSLSessionUniquePtr sessionPtr = sslSessionManager_.getRawSession();
   if (sessionPtr) {
     sessionResumptionAttempted_ = true;

folly/io/async/AsyncSSLSocket.h

@@ -832,8 +832,14 @@ class AsyncSSLSocket : public AsyncSocket {
     asyncOperationFinishCallback_ = std::move(cb);
   }
 
+  // Only enable if security negotiation is deferred
   // zero copy is not supported by openssl.
-  bool setZeroCopy(bool /*enable*/) override { return false; }
+  bool setZeroCopy(bool enable) override {
+    if (sslState_ == STATE_UNENCRYPTED) {
+      return AsyncSocket::setZeroCopy(enable);
+    }
+    return false;
+  }
 
  private:
   /**

folly/io/async/AsyncSocket.cpp

@@ -1153,6 +1153,11 @@ bool AsyncSocket::setZeroCopy(bool enable) {
       return false;
     }
 
+    // No-op, bail out early
+    if (enable == zeroCopyEnabled_) {
+      return true;
+    }
+
     int val = enable ? 1 : 0;
     int ret =
         netops_->setsockopt(fd_, SOL_SOCKET, SO_ZEROCOPY, &val, sizeof(val));