From 200e9154a03986074ff3bd9b76c2b600026548a1 Mon Sep 17 00:00:00 2001
From: p2r3 <p2r3@p2r3.com>
Date: Fri, 29 Aug 2025 16:11:56 +0300
Subject: [PATCH] implement timeout on stalling connections

---
 include/globals.h |  3 +++
 src/tools.c       | 14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/globals.h b/include/globals.h
index c12e8cd..8a6c8e2 100644
--- a/include/globals.h
+++ b/include/globals.h
@@ -50,6 +50,9 @@
 // only applies to player data. Block changes are written as soon as they
 // are made, but in much smaller portions.
 #define DISK_SYNC_INTERVAL 15000000
+// Time in microseconds to spend waiting for data transmission before
+// timing out. (default = 5s)
+#define NETWORK_TIMEOUT_TIME 5000000
 // If defined, scales the frequency at which player movement updates are
 // broadcast based on the amount of players, reducing overhead for higher
 // player counts. For very many players, makes movement look jittery.
diff --git a/src/tools.c b/src/tools.c
index eb4f3ac..a32079a 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -36,6 +36,10 @@ ssize_t recv_all (int client_fd, void *buf, size_t n, uint8_t require_first) {
   char *p = buf;
   size_t total = 0;
 
+  // Track time of last meaningful network update
+  // Used to handle timeout when client is stalling
+  int32_t last_update_time = get_program_time();
+
   // If requested, exit early when first byte not immediately available
   if (require_first) {
     ssize_t r = recv(client_fd, p, 1, MSG_PEEK);
@@ -52,6 +56,8 @@ ssize_t recv_all (int client_fd, void *buf, size_t n, uint8_t require_first) {
     ssize_t r = recv(client_fd, p + total, n - total, 0);
     if (r < 0) {
       if (errno == EAGAIN || errno == EWOULDBLOCK) {
+        // handle network timeout
+        if (get_program_time() - last_update_time > NETWORK_TIMEOUT_TIME) return -1;
         task_yield();
         continue;
       } else {
@@ -64,6 +70,7 @@ ssize_t recv_all (int client_fd, void *buf, size_t n, uint8_t require_first) {
       return total;
     }
     total += r;
+    last_update_time = get_program_time();
   }
 
   total_bytes_received += total;
@@ -75,11 +82,16 @@ ssize_t send_all (int client_fd, const void *buf, ssize_t len) {
   const uint8_t *p = (const uint8_t *)buf;
   ssize_t sent = 0;
 
+  // Track time of last meaningful network update
+  // Used to handle timeout when client is stalling
+  int32_t last_update_time = get_program_time();
+
   // Busy-wait (with task yielding) until all data has been sent
   while (sent < len) {
     ssize_t n = send(client_fd, p + sent, len - sent, MSG_NOSIGNAL);
     if (n > 0) { // some data was sent, log it
       sent += n;
+      last_update_time = get_program_time();
       continue;
     }
     if (n == 0) { // connection was closed, treat this as an error
@@ -88,6 +100,8 @@ ssize_t send_all (int client_fd, const void *buf, ssize_t len) {
     }
     // not yet ready to transmit, try again
     if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) {
+      // handle network timeout
+      if (get_program_time() - last_update_time > NETWORK_TIMEOUT_TIME) return -1;
       task_yield();
       continue;
     }