ESPSomfy-RTS/docs/KNOWN_ISSUES.md

Known Issues

Concurrent mutation during chunked /controller response

Status: fixed: reads in step 2, edits in step 3; command replies still read the live model (below). Introduced: 2026-04-19, alongside the chunked-response conversion of /controller (the original crash report was about cbuf::resize aborting async_tcp). Fixed: 2026-10-16, steps 2 and 3 of LOOP_QUEUE_PLAN.md.

What it was

The chunked /controller response read somfy.rooms, somfy.shades, somfy.groups and somfy.repeaters on async_tcp a piece at a time as the client's TCP window opened, for hundreds of ms to seconds. Anything that changed them meanwhile could make the document contradict itself: a deleted shade in shades but not in a group's linkedShades, two positions for one shade, a linked shade skipped or written twice. /discovery, /shades and the other reads had the same exposure, only shorter.

All eight read routes (/controller, /discovery, /rooms, /shades, /groups, /room, /shade, /group) now stream a ModelSnapshot that loop() fills, so each document describes one moment (ADR-0002). That is fix option (c), taken per read in a heap slot of about 5.6 KB.

Edits (step 3)

The handlers that changed the shade model on the web server task (adding, saving and deleting rooms, shades and groups; linking remotes, repeaters and group members; /setPaired; the sort orders) now hand the edit to loop() through the LoopQueue, and every client learns the result from a requestResult socket event. So /linkRemote can no longer race a received frame for a linked remote's rolling code: both now change it on loop(), in the order they happen.

Still open

• Command replies (/shadeCommand, /tiltCommand, /unpairShade, /setRollingCode, ...) still copy the one item they report from the live shade model on async_tcp, so a reply can show a value from the middle of a change. /room, /shade, /group and /groupOptions also check on the live model whether the item exists, because the status goes out before the snapshot is filled.
• The read routes would leave out an item that didn't fit their 3 KB unit; a test now proves none can, see Oversized read items are left out.

Oversized read items are left out

Status: guarded by a test (fix option (b)). It can't happen with today's fields, and a change that would make it happen fails test_snapshot_limits. Location: SnapshotWriter::overflowed in src/ModelSnapshot.cpp; the unit is SNAPSHOT_UNIT_SIZE in src/ModelSnapshot.h.

Summary

Every read route builds each room, shade, group and linked shade into a 3 KB unit before sending it. When one doesn't fit, the writer logs an ESP_LOGE line, skips that item and carries on, so the document stays valid JSON. The client gets no sign that anything is missing: the item just isn't in the list. Before step 2 only /controller did this; /discovery, /shades and the rest grew their buffer instead.

test_snapshot_limits fills a snapshot with the largest possible items: 20-character names of control characters (each escaped to \u00XX), all 7 linked remotes, 32 members in every group, and the widest value of every number. It checks that every read document written with the real unit is identical to the same document written with an unlimited one. The largest items are a shade at 1,097 bytes, a linked shade at 345, a group at 333 and a room at 159, against 3,072. The log line stays as a backstop.

Concrete failure modes

1. A shade is left out after a firmware change adds fields to it. It is missing from the config UI, and Home Assistant doesn't create an entity for it.
2. A group whose linkedShades entry doesn't fit loses that shade from its list.

Fix options (pick one later)

• (a) Fail loud. Add a list of the skipped item ids to the end of the document, and show a warning in the UI.
• (b) Check the size at build time. Work out the worst case for each item from the field limits and static_assert that it fits the buffer, so a change that breaks it doesn't build.

Related

• The same "lost without telling the client" problem as Large websocket events are dropped.

Large websocket events are dropped

Status: fixed (fix option (c)): the buffer is 4 KB, and the largest event provably fits. Location: JsonSockEvent in src/WResp.cpp, buffer g_response[MAX_SOCK_RESPONSE] (now 4096 bytes, defined in src/outputs/SocketEmitter.h).

Summary

Socket events are built into one static buffer. When a value doesn't fit, JsonSockEvent::_safecat marks the event as overflowed, and endEvent logs an error and doesn't send it. Clients never see malformed JSON. The event is simply lost, and the client isn't told.

Unlike the /controller HTTP crash, this path does not abort: there is no growing cbuf and no new[] on the send path.

What can be large

• remoteFrame (the frame log) lists every pulse of a received frame: up to MAX_TIMINGS = 300. A pulse recorded while waiting for a sync has no upper bound, so in theory each can be 10 digits: 300 × 11 bytes plus about 300 bytes of fields is about 3.8 KB. Real frames come to 1.8–2.1 KB, which was already at the old 2 KB limit. A static_assert in Transceiver.cpp fails the build if MAX_TIMINGS or the buffer change so that it no longer fits.
• The state events are small. shadeState has about 20 fields and no linked remotes, about 400 bytes. (The 1.3–1.5 KB figure this entry used to give was for a shade with its linked remotes, which only the read routes send.) groupState lists at most 32 shade ids. frequencyScan, memStatus, fwStatus, ethernet and requestResult have a few fixed fields each.

The 2 KB more of static RAM is the cost. The log line stays as a backstop.

Options that weren't taken

• (a) Fail loud: send a small error event in place of the dropped one so the client reloads the state.
• (b) Split large events across frames: the socket.io ack/chunk pattern, with matching client-side reassembly.

Related

• Not the same code path as the /controller crash. Solve independently.
• Worth grepping for JsonSockEvent usages that iterate collections (see references in SomfyEvents.cpp, Transceiver.cpp, ESPNetwork.cpp, GitOTA.cpp) to identify the most at-risk events.
• Group reads emit events from the web server task (fixed): a second task writing the same buffer.

Group reads emit events from the web server task

Status: fixed 2026-10-16, step 2 of LOOP_QUEUE_PLAN.md (fix option (a)). Read routes write from a ModelSnapshot, and the replies still written on async_tcp copy the group with snapshotGroup(), which works its flags out without changing the group or sending anything. Location: serializeGroupRef in src/entryPoints/Web.cpp called SomfyGroup::updateFlags() in src/SomfyGroup.cpp.

Summary

Serializing a group for an HTTP reply first calls group->updateFlags(). When the group's flags no longer match its shades', that writes group->flags, sends a groupState socket event and publishes the group's MQTT topics, all on the async_tcp task, while loop() sends events and publishes too.

Every socket event is formatted into the one static buffer g_response in src/outputs/SocketEmitter.cpp through the one JsonSockEvent in sockEmit. Two tasks emitting at once write over each other's event. The MQTT client (PubSubClient) isn't safe to use from two tasks either.

Reached from every route that serializes a group: /controller, /discovery, /groups, /group, /groupCommand, /addGroup, /saveGroup, /linkToGroup, /unlinkFromGroup and others.

Concrete failure modes

1. A groupState from a /groups request and a shadeState from loop() are formatted at the same time: clients receive garbled JSON, or an event with another event's fields.
2. The group's MQTT publish interleaves with one from loop() in the client's buffer, and the broker gets a broken packet or the connection drops.
3. group->flags is written on async_tcp while loop() updates the same group through updateGroupFlags().

It needs a group whose flags are out of date at the moment a client reads it, for example right after a sensor frame changed a linked shade's sun or wind flags, so it is rare.

Fix options

• (a) Drop updateFlags() from the serializers. loop() already keeps group flags current through updateGroupFlags(). This is part of step 2 of LOOP_QUEUE_PLAN.md: reads come from a ModelSnapshot that loop() fills, and serializers only read.
• (b) Only emit from loop(). Covered by ADR-0002 once nothing outside loop() changes the shade model.

Related

• ADR-0002: the loop task is the only writer of the shade model.
• Large websocket events are dropped: the same g_response buffer.

A saved WiFi passphrase or MQTT password can't be cleared from the UI

Status: open. A workaround exists (below). Introduced: 2026-10-18, when the device stopped sending stored secrets back to clients. Location: applySecret in src/Secrets.h, called from WifiSettings::fromJSON and MQTTSettings::fromJSON in src/ConfigSettings.cpp and from /connectwifi. The UI side is keepSavedPassphrase in Wifi and connectMQTT in MQTT, in data-src/index.js.

Summary

The settings routes report only whether a secret is stored (hasPassphrase, hasPassword), so the UI loads every secret field empty. The firmware decides what an empty secret in a request means, so that every UI version is safe, including one older than this change, which sends "" for the field it can no longer fill in:

Secret	Key absent	""	A value
WiFi passphrase	keep	keep, or clear if the same request changes the SSID	replace
MQTT password	keep	keep, or clear if the same request changes the username	replace
Login password, PIN	keep	keep	replace

Without "empty keeps", saving any other setting from an old UI would wipe the secret: for WiFi the device would reboot and drop into AP mode.

The cost: an empty value can't mean "no password" while the SSID or username stays the same. Switching to a different open network works.

The login password and PIN aren't affected. Neither can be empty, and security is turned off with the type selector.

Concrete failure modes

1. The network the device is on is changed to open on the router, keeping its SSID. Saving the network page with a blank passphrase keeps the old one. When a passphrase is set, WiFi.begin won't accept anything weaker than WPA2-PSK, so the device can't join the now-open network.
2. The MQTT broker stops requiring a password but keeps the username. The device keeps sending the old password.

Workaround

• MQTT: save once with a different username, then change it back and save again with the password blank.
• WiFi: there's no safe workaround. Saving a different SSID makes the device reboot and try to join that network.

Fix options

• (a) "Clear saved password" checkbox next to the WiFi passphrase and MQTT password fields, shown only when a value is stored. Since "" means keep, ticking it sends an explicit flag (clearPassphrase / clearPassword), which fromJSON turns into applySecret(..., identityChanged = true).

Port 80 routes don't check login

Status: open. Fix planned as PR A of SECURITY_PLAN.md. Location: registerWebUiRoutes in src/entryPoints/WebUiRoutes.cpp.

Summary

Only the ten port-80 routes that share a handler with port 8081 call isAuthenticated. The other ~60 check nothing, including every settings route, /restore, firmware updates, pairing and rolling codes. Logging in only hides parts of the UI. serveStatic("/") also serves shades.cfg and shades.tmp, which hold the rolling codes, to anyone.

Concrete failure modes

1. With a PIN or password set, any LAN client can PUT /saveSecurity and replace them, or change the network, MQTT or radio settings.
2. Any LAN client can download /shades.cfg and read every shade's remote address and rolling code.

API token key is public

Status: open. Fix planned as PR B of SECURITY_PLAN.md. Location: Web::createAPIToken in src/entryPoints/Web.cpp.

Summary

Tokens are HMAC(serverId, PIN-or-password + client IP). serverId is the last 3 bytes of the MAC address, and it is published in mDNS, in the retained MQTT serverId topic, in /discovery and in /loginContext. So the HMAC key gives no protection: whoever sees a token can try every PIN offline. Tokens never expire, and they are compared with a non-constant-time String comparison. serverId itself is an identity (HA's unique id) and stays public. Only the key is replaced.

CORS allows any origin

Status: open. Fix planned as PR A of SECURITY_PLAN.md. Location: DefaultHeaders in Web::begin, src/entryPoints/Web.cpp.

Summary

Every response carries Access-Control-Allow-Origin: *, Access-Control-Allow-Methods: PUT,POST,GET,OPTIONS and Access-Control-Allow-Headers: *. Any website open in a browser on the LAN can call the device and read the replies. With security None it can change every setting, without the user noticing.

Websocket has no auth

Status: open. Fix planned as PR A of SECURITY_PLAN.md. Location: SocketEmitter::wsEvent in src/outputs/SocketEmitter.cpp.

Summary

Anyone can connect to ws://host:8080/ and join any room. Clients can't change anything over it, but they receive all shade and group state, and room 0 (the frame log) carries received remote addresses and rolling codes. Browsers don't apply CORS to websockets, so a page from any origin can connect too.

/login has no rate limit

Status: open. Fix planned as PR C of SECURITY_PLAN.md. Location: Web::handleLogin in src/entryPoints/Web.cpp.

Summary

Failed logins aren't throttled. A digits-only 4-character PIN has 10,000 options and falls to an online attack within minutes. An alphanumeric one has about 1.7 million and lasts a day or two at about 10 attempts per second.