deuxyeux/RTNode-HeltecV4
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

v1.0.12: Fix link MTU clamping, echo-back prevention, oversized frame detection

Browse Source 
MTU Clamping (Bug 8a): Clamp link MTU signalling in LINKREQUEST packets
when forwarding through transport node, matching Python reference impl.
Without this, TCP endpoints negotiate 8192-byte segments that exceed the
V3's 1064-byte HDLC buffer, causing silent truncation and permanent
resource transfer stalls at ~70%.

Fixed MTU declaration (Bug 8b): Set FIXED_MTU=true on TcpInterface so
Transport uses HW_MTU for clamping decisions.

Oversized frame detection (Bug 8c): Track truncated HDLC frames and
drop them with a diagnostic log instead of silently delivering corrupt
data to Transport.

Echo-back prevention (v1.0.10): Track which TCP client originated each
inbound frame and skip that client in send_outgoing() to prevent
flooding TCP buffers.

Register local client interface: Enable Transport forwarding of
announces, link packets, and proofs to TCP clients.

Document all discovered microReticulum bugs in MICRORETICULUM_BUGS.md.
This commit is contained in:
James L
2026-02-28 12:49:30 -05:00
parent 4e5d4ee8ad
commit 1122e9a0ee
5 changed files with 259 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

66
lib/microReticulum/src/Transport.cpp
View File

@@ -1730,6 +1730,34 @@ static bool is_backbone_interface(const Interface& iface) {
TRACE("Transport::inbound: Packet is next-hop LINKREQUEST");
double now = OS::time();
double proof_timeout = now + Type::Link::ESTABLISHMENT_TIMEOUT_PER_HOP * std::max((uint8_t)1, remaining_hops);
// === MTU Clamping (v1.0.12) ===
// When forwarding a LINKREQUEST through this transport node,
// clamp the link MTU signalling to min(prev-hop, next-hop)
// interface HW_MTU. Without this, endpoints negotiate a
// segment size that exceeds this node's buffer capacity,
// causing silent truncation and resource transfer stalls.
uint16_t path_mtu = Link::mtu_from_lr_packet(packet);
if (path_mtu > 0) {
uint16_t ph_mtu = packet.receiving_interface().HW_MTU();
uint16_t nh_mtu = outbound_interface.HW_MTU();
if (nh_mtu == 0) {
DEBUG("MTU CLAMP: No next-hop HW MTU, stripping link MTU signalling");
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE);
} else if (!outbound_interface.AUTOCONFIGURE_MTU() && !outbound_interface.FIXED_MTU()) {
DEBUG("MTU CLAMP: Outbound interface doesn't support MTU config, stripping link MTU signalling");
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE);
} else {
if (nh_mtu < path_mtu || (ph_mtu > 0 && ph_mtu < path_mtu)) {
uint16_t clamped = std::min(nh_mtu, (ph_mtu > 0) ? ph_mtu : nh_mtu);
RNS::Type::Link::link_mode mode = Link::mode_from_lr_packet(packet);
Bytes clamped_mtu_bytes = Link::signalling_bytes(clamped, mode);
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE) + clamped_mtu_bytes;
DEBUGF("MTU CLAMP: path=%u ph=%u nh=%u -> clamped=%u", path_mtu, ph_mtu, nh_mtu, clamped);
}
}
}
LinkEntry link_entry(
now,
next_hop,
@@ -1848,6 +1876,25 @@ static bool is_backbone_interface(const Interface& iface) {
double now = OS::time();
double proof_timeout = now + Type::Link::ESTABLISHMENT_TIMEOUT_PER_HOP
* std::max((uint8_t)1, remaining_hops);
// === MTU Clamping (v1.0.12) ===
uint16_t path_mtu = Link::mtu_from_lr_packet(packet);
if (path_mtu > 0) {
uint16_t ph_mtu = packet.receiving_interface().HW_MTU();
uint16_t nh_mtu = outbound_interface.HW_MTU();
if (nh_mtu == 0) {
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE);
} else if (!outbound_interface.AUTOCONFIGURE_MTU() && !outbound_interface.FIXED_MTU()) {
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE);
} else if (nh_mtu < path_mtu || (ph_mtu > 0 && ph_mtu < path_mtu)) {
uint16_t clamped = std::min(nh_mtu, (ph_mtu > 0) ? ph_mtu : nh_mtu);
RNS::Type::Link::link_mode mode = Link::mode_from_lr_packet(packet);
Bytes clamped_mtu_bytes = Link::signalling_bytes(clamped, mode);
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE) + clamped_mtu_bytes;
DEBUGF("MTU CLAMP: local->backbone path=%u ph=%u nh=%u -> %u", path_mtu, ph_mtu, nh_mtu, clamped);
}
}
LinkEntry link_entry(
now, next_hop, outbound_interface, remaining_hops,
packet.receiving_interface(), packet.hops(),
@@ -1913,6 +1960,25 @@ static bool is_backbone_interface(const Interface& iface) {
double now = OS::time();
double proof_timeout = now + Type::Link::ESTABLISHMENT_TIMEOUT_PER_HOP
* std::max((uint8_t)1, remaining_hops);
// === MTU Clamping (v1.0.12) ===
uint16_t path_mtu = Link::mtu_from_lr_packet(packet);
if (path_mtu > 0) {
uint16_t ph_mtu = packet.receiving_interface().HW_MTU();
uint16_t nh_mtu = outbound_interface.HW_MTU();
if (nh_mtu == 0) {
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE);
} else if (!outbound_interface.AUTOCONFIGURE_MTU() && !outbound_interface.FIXED_MTU()) {
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE);
} else if (nh_mtu < path_mtu || (ph_mtu > 0 && ph_mtu < path_mtu)) {
uint16_t clamped = std::min(nh_mtu, (ph_mtu > 0) ? ph_mtu : nh_mtu);
RNS::Type::Link::link_mode mode = Link::mode_from_lr_packet(packet);
Bytes clamped_mtu_bytes = Link::signalling_bytes(clamped, mode);
new_raw = new_raw.left(new_raw.size() - Type::Link::LINK_MTU_SIZE) + clamped_mtu_bytes;
DEBUGF("MTU CLAMP: backbone->local path=%u ph=%u nh=%u -> %u", path_mtu, ph_mtu, nh_mtu, clamped);
}
}
LinkEntry link_entry(
now, next_hop, outbound_interface, remaining_hops,
packet.receiving_interface(), packet.hops(),

1
lib/microReticulum/src/Transport.h
View File

@@ -312,6 +312,7 @@ namespace RNS {
static void handle_tunnel(const Bytes& tunnel_id, const Interface& interface);
static void register_interface(Interface& interface);
static void deregister_interface(const Interface& interface);
static void register_local_client_interface(const Interface& interface) { _local_client_interfaces.insert(std::cref(interface)); }
inline static const std::map<Bytes, Interface&> get_interfaces() { return _interfaces; }
static void register_destination(Destination& destination);
static void deregister_destination(const Destination& destination);