From 15ca0675c042b0001d5e8fe0f256fda72ce02c9a Mon Sep 17 00:00:00 2001
From: Evgeny <me@jeka.su>
Date: Mon, 20 Jul 2026 00:47:38 +0300
Subject: [PATCH] =?UTF-8?q?=D0=91=D0=B5=D0=B7=D0=BE=D0=BF=D0=B0=D1=81?=
 =?UTF-8?q?=D0=BD=D0=BE=D1=81=D1=82=D1=8C:=20pubkey=20check=20=D0=BF=D1=80?=
 =?UTF-8?q?=D0=B8=20reusing=20=D0=BB=D0=B8=D0=BD=D0=BA=D0=B0=20+=20node=5F?=
 =?UTF-8?q?changed=20=D0=BF=D1=80=D0=B8=20=D0=BA=D0=BE=D0=BD=D1=84=D0=BB?=
 =?UTF-8?q?=D0=B8=D0=BA=D1=82=D0=B5=20=D0=B0=D0=B4=D1=80=D0=B5=D1=81=D0=B0?=
 =?UTF-8?q?=20=D1=87=D1=83=D0=B6=D0=BE=D0=B3=D0=BE=20=D0=BA=D0=BE=D0=BD?=
 =?UTF-8?q?=D0=BD=D0=B0?=
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---
 src/etcp_connections.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/etcp_connections.c b/src/etcp_connections.c
index f0ef5f58..870d06a7 100644
--- a/src/etcp_connections.c
+++ b/src/etcp_connections.c
@@ -1694,13 +1694,35 @@ void etcp_connections_read_callback_socket(socket_t sock, void* arg) {
 
     struct ETCP_LINK* existing_link = etcp_link_find_by_remote_id(conn, req->link_id);
     if (!existing_link) {
-        existing_link = etcp_link_find_by_addr(e_sock, &addr);
-        if (existing_link && existing_link->etcp == conn) {
-            DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "[%s] found existing outbound link by addr for incoming INIT, reusing link=%p",
-                       conn->log_name, existing_link);
-        } else {
-            existing_link = NULL;
+    existing_link = etcp_link_find_by_addr(e_sock, &addr);
+    if (existing_link && existing_link->etcp == conn) {
+        if (memcmp(conn->crypto_ctx.peer_public_key, sc.peer_public_key, SC_PUBKEY_SIZE)) {
+            DEBUG_WARN(DEBUG_CATEGORY_CONNECTION, "[%s] link address match but pubkey mismatch, firing node_changed", conn->log_name);
+            DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "pubkey mismatch on reused link for node %016llx", (unsigned long long)peer_id);
+            conn->callbacks_running = 1;
+            struct etcp_cbk_entry* cbe = conn->node_changed_cbks;
+            while (cbe) { struct etcp_cbk_entry* n = cbe->next; cbe->fn(conn, cbe->arg); cbe = n; }
+            conn->callbacks_running = 0;
+            errorcode = 67;
+            goto ec_fr;
         }
+        DEBUG_INFO(DEBUG_CATEGORY_CONNECTION, "[%s] found existing outbound link by addr for incoming INIT, reusing link=%p",
+                   conn->log_name, existing_link);
+    } else if (existing_link) {
+        struct ETCP_CONN* old_conn = existing_link->etcp;
+        DEBUG_WARN(DEBUG_CATEGORY_CONNECTION, "[%s] conflicting link at %s belongs to %s, firing node_changed",
+                   conn->log_name, sockaddr_storage_to_str(&addr).str, old_conn->log_name);
+        DEBUG_ERROR(DEBUG_CATEGORY_CRYPTO, "link address conflict for node %016llx, firing node_changed callbacks on %s",
+                    (unsigned long long)peer_id, old_conn->log_name);
+        old_conn->callbacks_running = 1;
+        struct etcp_cbk_entry* cbe = old_conn->node_changed_cbks;
+        while (cbe) { struct etcp_cbk_entry* n = cbe->next; cbe->fn(old_conn, cbe->arg); cbe = n; }
+        old_conn->callbacks_running = 0;
+        errorcode = 67;
+        goto ec_fr;
+    } else {
+        existing_link = NULL;
+    }
     }
 
     uint8_t send_reset = 0;