From b38f7a4aa2595e6b36208490d7df12960e4d98dc Mon Sep 17 00:00:00 2001
From: Martino Facchin <m.facchin@arduino.cc>
Date: Thu, 16 Jul 2026 17:09:56 +0200
Subject: [PATCH 1/2] tcp_server: allow a client to signal its status

The _connected flag was never restored to 0 when the previous client was being disconnected. Would be better to implement using cpp and friend classes, leaving a reference in the Client if generated by accept()
---
 src/tcp_client.h | 15 +++++++++++++--
 src/tcp_server.h | 16 +++++++++++++---
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/tcp_client.h b/src/tcp_client.h
index 84df9d2..a97df35 100644
--- a/src/tcp_client.h
+++ b/src/tcp_client.h
@@ -27,6 +27,7 @@
 #define DEFAULT_TCP_CLIENT_BUF_SIZE    512
 #define TCP_RESPONSE_HEADER_SIZE       20   // max size of msg_id plus RCP headers for a TCP response
 
+void disconnect_server(void* opaque_server);
 
 template<size_t BufferSize=DEFAULT_TCP_CLIENT_BUF_SIZE>
 class BridgeTCPClient : public Client {
@@ -37,11 +38,16 @@ class BridgeTCPClient : public Client {
     RingBufferN<BufferSize> temp_buffer;
     struct k_mutex client_mutex{};
     bool _connected = false;
+    void* opaque_server = nullptr;  // Pointer to the server that spawned this client, if any
 
 public:
     explicit BridgeTCPClient(BridgeClass& bridge): bridge(&bridge) {}
 
-    BridgeTCPClient(BridgeClass& bridge, uint32_t connection_id, bool connected=true): bridge(&bridge), connection_id(connection_id), _connected {connected} {}
+    BridgeTCPClient(BridgeClass& bridge, uint32_t connection_id, bool connected=false, void* opaque_server=nullptr): bridge(&bridge), connection_id(connection_id), _connected{connected}, opaque_server(opaque_server) {}
+
+    bool operator==(const BridgeTCPClient& whs) {
+        return connection_id == whs.connection_id;
+    }
 
     bool begin() {
         k_mutex_init(&client_mutex);
@@ -127,6 +133,9 @@ class BridgeTCPClient : public Client {
 
     int read() override {
         uint8_t c;
+        if (!temp_buffer.available()) {
+            return -1;
+        }
         read(&c, 1);
         return c;
     }
@@ -165,6 +174,9 @@ class BridgeTCPClient : public Client {
         if (_connected) {
             _connected = !bridge->call(TCP_CLOSE_METHOD, connection_id).result(msg);
         }
+        if (opaque_server) {
+            disconnect_server(opaque_server);
+        }
         k_mutex_unlock(&client_mutex);
     }
 
@@ -219,7 +231,6 @@ class BridgeTCPClient : public Client {
 
         k_mutex_unlock(&client_mutex);
     }
-
 };
 
 
diff --git a/src/tcp_server.h b/src/tcp_server.h
index dc863a6..d2de3eb 100644
--- a/src/tcp_server.h
+++ b/src/tcp_server.h
@@ -64,12 +64,12 @@ class BridgeTCPServer final: public Server {
 
         if (!_listening) {  // Not listening -> return disconnected (invalid) client
             k_mutex_unlock(&server_mutex);
-            return BridgeTCPClient<BufferSize>(*bridge, 0, false);
+            return BridgeTCPClient<BufferSize>(*bridge, 0, false, this);
         }
 
         if (_connected) {   // Connection already established return a client copy
             k_mutex_unlock(&server_mutex);
-            return BridgeTCPClient<BufferSize>(*bridge, connection_id);
+            return BridgeTCPClient<BufferSize>(*bridge, connection_id, true, this);
         }
 
         // Accept a connection
@@ -77,8 +77,9 @@ class BridgeTCPServer final: public Server {
         _connected = ret;
 
         k_mutex_unlock(&server_mutex);
+
         // If no connection established return a disconnected (invalid) client
-        return ret? BridgeTCPClient<BufferSize>(*bridge, connection_id) : BridgeTCPClient<BufferSize>(*bridge, 0, false);
+        return ret? BridgeTCPClient<BufferSize>(*bridge, connection_id, true, this) : BridgeTCPClient<BufferSize>(*bridge, 0, false, this);
     }
 
     size_t write(uint8_t c) override {
@@ -152,4 +153,13 @@ class BridgeTCPServer final: public Server {
 
 };
 
+inline void disconnect_server(void* opaque_server) {
+
+    if (opaque_server) {
+        auto server = static_cast<BridgeTCPServer<>*>(opaque_server);
+        server->disconnect();
+    }
+}
+
+
 #endif //BRIDGE_TCP_SERVER_H
\ No newline at end of file

From ea8e0cead09af12f9ef6968f3c6290aa915cd68e Mon Sep 17 00:00:00 2001
From: Martino Facchin <m.facchin@arduino.cc>
Date: Fri, 17 Jul 2026 10:34:12 +0200
Subject: [PATCH 2/2] tcp_client: close connection on failed write()

---
 src/tcp_client.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/tcp_client.h b/src/tcp_client.h
index a97df35..c4c3774 100644
--- a/src/tcp_client.h
+++ b/src/tcp_client.h
@@ -119,6 +119,9 @@ class BridgeTCPClient : public Client {
         k_mutex_lock(&client_mutex, K_FOREVER);
         const bool ok = bridge->call(TCP_WRITE_METHOD, connection_id, payload).result(written);
         k_mutex_unlock(&client_mutex);
+        if (!ok) {
+            stop();
+        }
         return ok? written : 0;
     }