From 2ff7a15d1ef0620a6ba570c238c3666e5bde2eb7 Mon Sep 17 00:00:00 2001
From: Craig Raw <craigraw@gmail.com>
Date: Thu, 31 Jul 2025 10:34:56 +0200
Subject: [PATCH] add padding to writes when connected over tls

---
 .../sparrow/net/TcpOverTlsTransport.java      | 19 +++++++++++++++++++
 .../sparrow/net/TcpTransport.java             |  4 ++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/sparrowwallet/sparrow/net/TcpOverTlsTransport.java b/src/main/java/com/sparrowwallet/sparrow/net/TcpOverTlsTransport.java
index 4da5d045..9554ae2d 100644
--- a/src/main/java/com/sparrowwallet/sparrow/net/TcpOverTlsTransport.java
+++ b/src/main/java/com/sparrowwallet/sparrow/net/TcpOverTlsTransport.java
@@ -16,6 +16,7 @@ import java.security.cert.Certificate;
 
 public class TcpOverTlsTransport extends TcpTransport {
     private static final Logger log = LoggerFactory.getLogger(TcpOverTlsTransport.class);
+    public static final int PAD_TO_MULTIPLE_OF_BYTES = 96;
 
     protected final SSLSocketFactory sslSocketFactory;
 
@@ -41,6 +42,24 @@ public class TcpOverTlsTransport extends TcpTransport {
         sslSocketFactory = sslContext.getSocketFactory();
     }
 
+    @Override
+    protected void writeRequest(String request) throws IOException {
+        int currentLength = request.length();
+        int targetLength;
+        if(currentLength % PAD_TO_MULTIPLE_OF_BYTES == 0) {
+            targetLength = currentLength;
+        } else {
+            targetLength = ((currentLength / PAD_TO_MULTIPLE_OF_BYTES) + 1) * PAD_TO_MULTIPLE_OF_BYTES;
+        }
+
+        int paddingNeeded = targetLength - currentLength;
+        if(paddingNeeded > 0) {
+            super.writeRequest(request + " ".repeat(paddingNeeded));
+        } else {
+            super.writeRequest(request);
+        }
+    }
+
     private TrustManager[] getTrustManagers(File crtFile) throws IOException, CertificateException, NoSuchAlgorithmException, KeyStoreException {
         if(crtFile == null) {
             return new TrustManager[] {
diff --git a/src/main/java/com/sparrowwallet/sparrow/net/TcpTransport.java b/src/main/java/com/sparrowwallet/sparrow/net/TcpTransport.java
index 8a10494a..95528f4e 100644
--- a/src/main/java/com/sparrowwallet/sparrow/net/TcpTransport.java
+++ b/src/main/java/com/sparrowwallet/sparrow/net/TcpTransport.java
@@ -97,7 +97,7 @@ public class TcpTransport implements CloseableTransport, TimeoutCounter {
         }
     }
 
-    private void writeRequest(String request) throws IOException {
+    protected void writeRequest(String request) throws IOException {
         if(log.isTraceEnabled()) {
             log.trace("Sending to electrum server at " + server + ": " + request);
         }
@@ -106,7 +106,7 @@ public class TcpTransport implements CloseableTransport, TimeoutCounter {
             throw new IllegalStateException("Socket connection has not been established.");
         }
 
-        PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())));
+        PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream(), StandardCharsets.UTF_8)));
         out.println(request);
         out.flush();
     }