Update.

rproxy.c

@@ -1706,12 +1706,34 @@ void close_connection(int fd) {
     // Prevent double-closing
     if (conn->fd == -1) return; 
 
-    int pair_fd = -1;
-    if (conn->pair && conn->pair->fd != -1) {
-        pair_fd = conn->pair->fd;
-        conn->pair->pair = NULL;
+    connection_t *pair = conn->pair;
+
+    // --- START: ROBUST STATE & PAIR MANAGEMENT FIX ---
+
+    // Decouple the pair immediately to prevent circular logic.
+    if (pair) {
+        pair->pair = NULL;
     }
 
+    // If the connection being closed is a CLIENT, we must also close its upstream pair.
+    if (conn->type == CONN_TYPE_CLIENT && pair) {
+        close_connection(pair->fd);
+    }
+
+    // If the connection being closed is an UPSTREAM, its client pair must be
+    // reset to handle the next keep-alive request. This is the core of the fix.
+    if (conn->type == CONN_TYPE_UPSTREAM && pair && pair->type == CONN_TYPE_CLIENT) {
+        log_info("[STATE-FIX] Upstream fd=%d closed. Resetting client fd=%d for next request.", fd, pair->fd);
+        pair->state = CLIENT_STATE_READING_HEADERS;
+
+        // A new request might have been read into the buffer due to the race condition.
+        // We must attempt to process it now to serve it correctly.
+        if (buffer_available_read(&pair->read_buf) > 0) {
+            handle_client_read(pair);
+        }
+    }
+    // --- END: ROBUST STATE & PAIR MANAGEMENT FIX ---
+
     // Record request end if needed
     if (conn->vhost_stats && conn->request_start_time > 0) {
         monitor_record_request_end(conn->vhost_stats, conn->request_start_time);
@@ -1726,7 +1748,7 @@ void close_connection(int fd) {
         }
     }
 
-    log_debug("Closing connection on fd %d, pair %d, remaining: %d", fd, pair_fd, monitor.active_connections);
+    log_debug("Closing connection on fd %d, remaining: %d", fd, monitor.active_connections);
 
     // Remove from epoll before closing
     epoll_ctl(epoll_fd, EPOLL_CTL_DEL, fd, NULL);
@@ -1749,13 +1771,11 @@ void close_connection(int fd) {
     memset(conn, 0, sizeof(connection_t));
     conn->type = CONN_TYPE_UNUSED;
     conn->fd = -1;
-
-    // Close the paired connection
-    if (pair_fd != -1) {
-        close_connection(pair_fd);
-    }
 }
 
+
+
+
 void connect_to_upstream(connection_t *client, const char *data, size_t data_len) {
     if (!client || !data) return;
 
@@ -2110,15 +2130,16 @@ static void handle_forwarding(connection_t *conn) {
         return;
     }
 
-    // 1. Read data from the source connection (either client or upstream).
+    // 1. Read data from the source connection.
     int bytes_read = do_read(conn);
     
-    // 2. Forward any data we just read to the paired connection's write buffer.
+    // 2. Forward any data we just read to the paired connection.
     size_t data_to_forward = buffer_available_read(&conn->read_buf);
     if (data_to_forward > 0) {
+        // --- SYNTAX FIX IS HERE ---
         if (buffer_ensure_capacity(&pair->write_buf, pair->write_buf.tail + data_to_forward) < 0) {
             log_error("Failed to grow write buffer for forwarding");
-            close_connection(conn->fd); // Close the pair of connections on memory error.
+            close_connection(conn->fd);
             return;
         }
         
@@ -2126,52 +2147,21 @@ static void handle_forwarding(connection_t *conn) {
                conn->read_buf.data + conn->read_buf.head,
                data_to_forward);
         pair->write_buf.tail += data_to_forward;
+        // --- END OF SYNTAX FIX ---
         buffer_consume(&conn->read_buf, data_to_forward);
         
-        // Make sure the event loop knows the pair is ready to be written to.
         modify_epoll(pair->fd, EPOLLIN | EPOLLOUT);
     }
     
-    // 3. Handle connection state changes (EOF or errors).
+    // 3. On any read error or EOF, close the connection.
+    // The new logic in `close_connection` will correctly handle the state of the pair.
     if (bytes_read <= 0 && (errno != EAGAIN && errno != EWOULDBLOCK)) {
-        if (bytes_read < 0) { // A real read error occurred.
-            log_debug("Read error on fd=%d while forwarding. Closing connection.", conn->fd);
-            close_connection(conn->fd); // This will recursively close the pair.
-            return;
-        }
-
-        // --- ROBUST FIX FOR KEEP-ALIVE RACE CONDITION ---
-        // At this point, bytes_read is 0, meaning one side has closed its connection (EOF).
-        
-        log_info("[ROUTING-EOF] EOF on fd=%d (type=%s)", conn->fd,
-                 (conn->type == CONN_TYPE_CLIENT) ? "CLIENT" : "UPSTREAM");
-
-        if (conn->type == CONN_TYPE_UPSTREAM) {
-            // **This is the critical fix.** The upstream server finished its response.
-            // The client connection must be immediately reset to handle the next keep-alive request.
-            if (pair->type == CONN_TYPE_CLIENT) {
-                log_info("[ROUTING-KEEPALIVE] Upstream fd=%d finished. Resetting client fd=%d.", conn->fd, pair->fd);
-                
-                // Reset client state to stop forwarding and prepare for new headers.
-                pair->state = CLIENT_STATE_READING_HEADERS;
-                pair->pair = NULL; // Decouple from this now-finished upstream connection.
-                
-                // Check for pipelined requests that may have already arrived.
-                if (buffer_available_read(&pair->read_buf) > 0) {
-                    handle_client_read(pair);
-                }
-            }
-            // The upstream connection's job is done. Close it, leaving the client open.
-            close_connection(conn->fd);
-
-        } else if (conn->type == CONN_TYPE_CLIENT) {
-            // The client has closed its side of the connection.
-            // In this case, we perform a full teardown of both connections.
-            close_connection(conn->fd);
-        }
+        close_connection(conn->fd);
     }
 }
 
+
+
 static void handle_ssl_handshake(connection_t *conn) {
     if (!conn->ssl || conn->ssl_handshake_done) return;