fix: SSL / TLS handshake trap

src/unlocker/proxy.cpp

@@ -267,14 +267,36 @@ void Proxy::handleClient(SOCKET clientSocket)
     SSL_CTX* hostCtx = _certManager.createHostContext(host);
     if (!hostCtx) return;
 
+    auto sslHandshake = [](SSL* ssl, bool isAccept, SOCKET s) -> bool {
+        while (true)
+        {
+            int ret = isAccept ? SSL_accept(ssl) : SSL_connect(ssl);
+            if (ret > 0) return true;
+            int err = SSL_get_error(ssl, ret);
+            if (err == SSL_ERROR_WANT_READ || err == SSL_ERROR_WANT_WRITE)
+            {
+                fd_set fds;
+                FD_ZERO(&fds);
+                FD_SET(s, &fds);
+                struct timeval tv = {1, 0};
+                if (err == SSL_ERROR_WANT_READ)
+                    select(0, &fds, NULL, NULL, &tv);
+                else
+                    select(0, NULL, &fds, NULL, &tv);
+                continue;
+            }
+            return false;
+        }
+    };
+
     SSL_ptr clientSSL(SSL_new(hostCtx));
     SSL_set_fd(clientSSL.get(), (int)clientGuard);
-    if (SSL_accept(clientSSL.get()) <= 0) return;
+    if (!sslHandshake(clientSSL.get(), true, clientGuard)) return;
 
     SSL_ptr remoteSSL(SSL_new(_clientCtx));
     SSL_set_fd(remoteSSL.get(), (int)remoteGuard);
     SSL_set_tlsext_host_name(remoteSSL.get(), host.c_str());
-    if (SSL_connect(remoteSSL.get()) <= 0) return;
+    if (!sslHandshake(remoteSSL.get(), false, remoteGuard)) return;
 
     /*
         traffic handler