v1.1.5 - Fix CRITICAL segfault: Use wrapper nodes for no-kind-filter subscriptions

The kind index optimization in v1.1.4 introduced a critical bug that caused
segmentation faults in production. The bug was in add_subscription_to_kind_index()
which directly assigned sub->next for no-kind-filter subscriptions, corrupting
the main active_subscriptions linked list.

Root Cause:
- subscription_t has only ONE 'next' pointer used by active_subscriptions list
- Code tried to reuse 'next' for no_kind_filter_subs list
- This overwrote the active_subscriptions linkage, breaking list traversal
- Result: segfaults when iterating subscriptions

Fix:
- Added no_kind_filter_node_t wrapper structure (like kind_subscription_node_t)
- Changed no_kind_filter_subs from subscription_t* to no_kind_filter_node_t*
- Updated add/remove functions to use wrapper nodes
- Updated broadcast function to iterate through wrapper nodes

This follows the same pattern already used for kind_index entries and
prevents any corruption of the subscription structure's next pointer.

relay.pid

@@ -1 +1 @@
-1912734
+1931355

src/main.h

@@ -13,8 +13,8 @@
 // Using CRELAY_ prefix to avoid conflicts with nostr_core_lib VERSION macros
 #define CRELAY_VERSION_MAJOR 1
 #define CRELAY_VERSION_MINOR 1
-#define CRELAY_VERSION_PATCH 4
-#define CRELAY_VERSION "v1.1.4"
+#define CRELAY_VERSION_PATCH 5
+#define CRELAY_VERSION "v1.1.5"
 
 // Relay metadata (authoritative source for NIP-11 information)
 #define RELAY_NAME "C-Relay"

src/subscriptions.c

@@ -100,10 +100,17 @@ void add_subscription_to_kind_index(subscription_t* sub) {
         filter = filter->next;
     }
     
-    // If subscription has no kind filter, add to no-kind-filter list
+    // If subscription has no kind filter, add to no-kind-filter list using wrapper node
     if (!has_kind_filter) {
-        sub->next = g_subscription_manager.no_kind_filter_subs;
-        g_subscription_manager.no_kind_filter_subs = sub;
+        no_kind_filter_node_t* node = malloc(sizeof(no_kind_filter_node_t));
+        if (!node) {
+            DEBUG_ERROR("add_subscription_to_kind_index: failed to allocate no-kind-filter node");
+            return;
+        }
+        
+        node->subscription = sub;
+        node->next = g_subscription_manager.no_kind_filter_subs;
+        g_subscription_manager.no_kind_filter_subs = node;
         DEBUG_TRACE("KIND_INDEX: Added subscription '%s' to no-kind-filter list", sub->id);
     }
 }
@@ -130,11 +137,13 @@ void remove_subscription_from_kind_index(subscription_t* sub) {
         }
     }
     
-    // Remove from no-kind-filter list
-    subscription_t** current = &g_subscription_manager.no_kind_filter_subs;
+    // Remove from no-kind-filter list if present
+    no_kind_filter_node_t** current = &g_subscription_manager.no_kind_filter_subs;
     while (*current) {
-        if (*current == sub) {
+        if ((*current)->subscription == sub) {
+            no_kind_filter_node_t* to_free = *current;
             *current = (*current)->next;
+            free(to_free);
             DEBUG_TRACE("KIND_INDEX: Removed subscription '%s' from no-kind-filter list", sub->id);
             break;
         }
@@ -797,12 +806,12 @@ int broadcast_event_to_subscriptions(cJSON* event) {
     }
 
     // Add subscriptions with no kind filter (must check against all events)
-    subscription_t* no_kind_sub = g_subscription_manager.no_kind_filter_subs;
-    while (no_kind_sub && candidate_count < MAX_TOTAL_SUBSCRIPTIONS) {
-        if (no_kind_sub->active) {
-            candidates_to_check[candidate_count++] = no_kind_sub;
+    no_kind_filter_node_t* no_kind_node = g_subscription_manager.no_kind_filter_subs;
+    while (no_kind_node && candidate_count < MAX_TOTAL_SUBSCRIPTIONS) {
+        if (no_kind_node->subscription && no_kind_node->subscription->active) {
+            candidates_to_check[candidate_count++] = no_kind_node->subscription;
         }
-        no_kind_sub = no_kind_sub->next;
+        no_kind_node = no_kind_node->next;
     }
 
     DEBUG_TRACE("BROADCAST: Checking %d candidate subscriptions (kind index optimization)", candidate_count);

src/subscriptions.h

@@ -69,6 +69,12 @@ typedef struct kind_subscription_node {
     struct kind_subscription_node* next;       // Next subscription for this kind
 } kind_subscription_node_t;
 
+// No-kind-filter list entry - wrapper to avoid corrupting subscription->next pointer
+typedef struct no_kind_filter_node {
+    subscription_t* subscription;              // Pointer to subscription
+    struct no_kind_filter_node* next;          // Next subscription in no-kind list
+} no_kind_filter_node_t;
+
 // Per-IP connection tracking
 typedef struct ip_connection_info {
     char ip_address[CLIENT_IP_MAX_LENGTH];  // IP address
@@ -87,7 +93,7 @@ struct subscription_manager {
 
     // Kind-based index for fast subscription lookup (10x performance improvement)
     kind_subscription_node_t* kind_index[65536];  // Array of subscription lists, one per kind
-    subscription_t* no_kind_filter_subs;          // Subscriptions with no kind filter (must check all events)
+    no_kind_filter_node_t* no_kind_filter_subs;   // Subscriptions with no kind filter (wrapper nodes)
 
     // Configuration
     int max_subscriptions_per_client;       // Default: 20