From 1b3c4552fb9ccd549f4f87f2c0a5529aadbd60f5 Mon Sep 17 00:00:00 2001
From: evgeny <evgeny@adaptto.ru>
Date: Fri, 23 Oct 2026 10:24:29 +0200
Subject: [PATCH] Account for transmission IDs in MTU and packet diagnostics

---
 src/transport_layer/etcp.c           | 2 +-
 src/transport_layer/etcp_debug.c     | 6 +++---
 src/transport_layer/pkt_normalizer.c | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/transport_layer/etcp.c b/src/transport_layer/etcp.c
index 99cad98a..8dd1da07 100644
--- a/src/transport_layer/etcp.c
+++ b/src/transport_layer/etcp.c
@@ -1674,7 +1674,7 @@ void etcp_update_mtu(struct ETCP_CONN* etcp) {
             int max_udp = IP_UDP_OVERHEAD_V4;
             for (struct ETCP_LINK* l = etcp->links; l; l = l->next)
                 if (l->remote_addr.ss_family == AF_INET6) max_udp = IP_UDP_OVERHEAD_V6;
-            etcp->normalizer->frag_size = etcp->mtu - ACK_REZERV - max_udp - UDP_SC_HDR_SIZE - ETCP_SESSION_HEADER_SIZE;
+            etcp->normalizer->frag_size = etcp->mtu - max_udp - SC_ENCRYPT_OVERHEAD - ETCP_PAYLOAD_HEADER_SIZE - ACK_REZERV;
         }
     }
 }
diff --git a/src/transport_layer/etcp_debug.c b/src/transport_layer/etcp_debug.c
index ee5f8518..c299cf6f 100644
--- a/src/transport_layer/etcp_debug.c
+++ b/src/transport_layer/etcp_debug.c
@@ -47,7 +47,7 @@ void etcp_dump_pkt_sections(struct ETCP_DGRAM* pkt, struct ETCP_LINK* link, int
                                      ((uint32_t)data[offset + 4] << 16) | ((uint32_t)data[offset + 5] << 24);
                 uint16_t ack_rx_dup = data[offset + 6] | (data[offset + 7] << 8);
                 pos += snprintf(buf + pos, sizeof(buf) - pos, " ack=%u/%d dup=%u", ack_last_delivered, ack_count, ack_rx_dup);
-                offset += 8 + ack_count * 8;
+                offset += ETCP_ACK_BASE_SIZE + ack_count * ETCP_ACK_ENTRY_SIZE;
                 break;
             }
             case ETCP_SECTION_TIMESTAMP: {
@@ -60,10 +60,10 @@ void etcp_dump_pkt_sections(struct ETCP_DGRAM* pkt, struct ETCP_LINK* link, int
                 break;
             }
             case ETCP_SECTION_PAYLOAD: {
-                if (offset + 5 > len) { offset = len; break; }
+                if (offset + ETCP_PAYLOAD_HEADER_SIZE > len) { offset = len; break; }
                 payload_seq = (uint32_t)data[offset + 1] | ((uint32_t)data[offset + 2] << 8) |
                               ((uint32_t)data[offset + 3] << 16) | ((uint32_t)data[offset + 4] << 24);
-                payload_size = len - offset - 5;
+                payload_size = len - offset - ETCP_PAYLOAD_HEADER_SIZE;
                 has_payload = 1;
                 pos += snprintf(buf + pos, sizeof(buf) - pos, " payload=%u(seq=%u)", payload_size, payload_seq);
                 offset = len;
diff --git a/src/transport_layer/pkt_normalizer.c b/src/transport_layer/pkt_normalizer.c
index a03dce41..7ed37e37 100644
--- a/src/transport_layer/pkt_normalizer.c
+++ b/src/transport_layer/pkt_normalizer.c
@@ -42,8 +42,8 @@ struct PKTNORM* pn_init(struct ETCP_CONN* etcp) {
     int max_udp = IP_UDP_OVERHEAD_V4;
     for (struct ETCP_LINK* l = etcp->links; l; l = l->next)
         if (l->remote_addr.ss_family == AF_INET6) max_udp = IP_UDP_OVERHEAD_V6;
-    pn->frag_size = etcp->mtu - ACK_REZERV - max_udp - UDP_SC_HDR_SIZE - ETCP_SESSION_HEADER_SIZE;
-    int min_frag = max_udp + UDP_SC_HDR_SIZE + ACK_REZERV;
+    pn->frag_size = etcp->mtu - max_udp - SC_ENCRYPT_OVERHEAD - ETCP_PAYLOAD_HEADER_SIZE - ACK_REZERV;
+    int min_frag = max_udp + SC_ENCRYPT_OVERHEAD + ETCP_PAYLOAD_HEADER_SIZE + ACK_REZERV;
     if (etcp->mtu < min_frag || pn->frag_size > etcp->mtu) {
         DEBUG_ERROR(DEBUG_CATEGORY_ETCP, "MTU %d too small (min %d)", etcp->mtu, min_frag);
         pn->frag_size = etcp->mtu;