Node / meshtastic / Meshtastic-Android / files / core / takserver / src / commonMain / kotlin / org / meshtastic / core / takserver / CoTDetailStripper.kt

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T8b949e/*

* Copyright (c) 2026 Meshtastic LLC

*

* This program is free software: you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation, either version 3 of the License, or

* (at your option) any later version.

*

* This program is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU General Public License

* along with this program. If not, see <https://www.gnu.org/licenses/>.

*/

Tff7b72package T7ee787org.meshtastic.core.takserver

T8b949e/**

* Removes bloat elements from the `<detail>` content of a CoT event before it is stuffed into a

* [org.meshtastic.proto.TAKPacketV2] `raw_detail` field for mesh transmission.

*

* # Why this exists

*

* A LoRa mesh packet has a hard payload limit of [org.meshtastic.proto.Constants.DATA_PAYLOAD_LEN] = 233 bytes for the

* entire encoded `Data` proto (portnum + payload + reply_id + emoji). Subtracting the wrapper overhead leaves roughly

* **~225 bytes** for the TAK wire payload, and the wire payload itself is `[1 byte dict-id flag][zstd-compressed

* TAKPacketV2 protobuf]`.

*

* ATAK emits CoT events with rich visual metadata that is **never useful over a mesh**: icon set paths, ARGB colors,

* shape geometry, archive flags, file references, etc. A typical `u-d-c-c` (user-drawn circle) event from ATAK is

* **800+ bytes of XML**, of which maybe 80 bytes are actually meaningful to a receiving node. Even with dictionary

* compression, the full payload overflows the MTU.

*

* This stripper deletes elements the receiving node can synthesize or ignore, leaving only the minimum needed to

* rebuild a usable `<event>` on the other side: who sent it, where they are, what team/role they're on, battery status,

* chat content, and the high-level CoT type (which rides separately on [TAKPacketV2.cot_type_id] /

* [TAKPacketV2.cot_type_str]).

*

* # What gets dropped

*

* **Cosmetic / rendering-only** (pure visual, no situational awareness value):

* - `<color .../>` — ARGB stroke/fill colors

* - `<strokeColor .../>`, `<strokeWeight .../>`, `<fillColor .../>` — shape styling

* - `<labels_on .../>` — label visibility toggle

* - `<usericon .../>` — icon set path (`COT_MAPPING_2525B/...`)

* - `<model .../>` — 3D model reference

*

* **Geometric detail** (we keep lat/lon on the event; shape primitives are too big):

* - `<shape>...</shape>` — ellipse/polyline/polygon geometry

* - `<height .../>`, `<height_unit .../>` — rendering hints

*

* **Resource references** (useless without the resource being reachable):

* - `<fileshare .../>` — file transfer references

* - `<__video .../>` — video stream URL

*

* **Flags and redundant metadata**:

* - `<archive/>` — "save to archive" flag

* - `<precisionlocation .../>` — redundant with the event's `<point>` attributes

* - `<tog .../>` — rectangle "toggle" UI state flag

* - `<_flow-tags_ .../>` — TAK Server routing metadata (server-to-server, not needed on mesh)

*

* # What gets preserved

*

* Anything the stripper doesn't explicitly match is passed through untouched. That includes all of the structured

* elements that the regular [CoTXmlParser] understands (contact, __group, status, track, remarks, __chat, chatgrp,

* link, uid, __serverdestination) plus any unknown extensions — better to over-preserve than silently drop something

* the receiving ATAK actually needs.

*

* # Whitespace

*

* All inter-element whitespace and indentation is collapsed. Whitespace inside text nodes (e.g. `<remarks>hello

* world</remarks>`) is preserved.

*

* # Not a real XML parser

*

* This is intentionally string/regex based, not DOM. The input is a small, well-formed fragment produced by ATAK's

* serializer, so a full parser is overkill — and we want this to be dependency-free so it can run on every KMP target

* without pulling in xmlutil for a one-off job. If ATAK starts emitting namespaced elements or embedded CDATA that

* tangles with these patterns, the stripper will leave them alone rather than corrupt the output, which is the safer

* failure mode.

*/

Tff7b72internal Tff7b72object T56d364CoTDetailStripper Tb4b4b4{

T8b949e/**

* Element names whose entire subtree (or self-closing tag) is removed.

*

* Order matters only for documentation. Each entry is tried against both the self-closing form `<name .../>` and

* the paired form `<name ...>...</name>`.

*/

Tff7b72private Tff7b72val Te6edf3STRIPPED_ELEMENTS Tff7b72=

Te6edf3listOfTb4b4b4(

T8b949e// Cosmetic / rendering

Ta5d6ff"Ta5d6ffcolorTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ffstrokeColorTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ffstrokeWeightTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6fffillColorTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6fflabels_onTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ffusericonTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ffmodelTa5d6ff"Tb4b4b4,

T8b949e// Geometric

Ta5d6ff"Ta5d6ffshapeTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ffheightTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ffheight_unitTa5d6ff"Tb4b4b4,

T8b949e// Resource refs

Ta5d6ff"Ta5d6fffileshareTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ff__videoTa5d6ff"Tb4b4b4,

T8b949e// Flags / redundant

Ta5d6ff"Ta5d6ffarchiveTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ffprecisionlocationTa5d6ff"Tb4b4b4,

T8b949e// Rectangle/polyline "toggle" UI flag, and TAK Server routing metadata.

T8b949e// The underscore-prefixed element names are legal XML identifiers ATAK uses

T8b949e// for internal state that receiving meshtastic nodes have no use for.

Ta5d6ff"Ta5d6fftogTa5d6ff"Tb4b4b4,

Ta5d6ff"Ta5d6ff_flow-tags_Ta5d6ff"Tb4b4b4,

Tb4b4b4)

T8b949e/**

* Pre-compiled regex list: for each stripped element, one pattern that matches either a self-closing tag or a

* paired open/close tag (non-greedy content).

*

* `[^>]*?` inside the open tag tolerates attribute quoting with both single and double quotes but bails if it

* encounters a `>` (so it won't accidentally swallow unrelated content).

*

* The leading `(?s)` inline flag is the KMP-portable equivalent of `RegexOption.DOT_MATCHES_ALL` — it lets `.`

* match newlines so a multi-line `<shape>...</shape>` subtree is captured in one pass.

* `RegexOption.DOT_MATCHES_ALL` itself is JVM-only and breaks the Kotlin/Native build.

*/

Tff7b72private Tff7b72val Te6edf3STRIPPED_ELEMENT_PATTERNSTb4b4b4: Te6edf3ListTff7b72<Te6edf3RegexTff7b72> Tff7b72=

Te6edf3STRIPPED_ELEMENTSTb4b4b4.Te6edf3map Tb4b4b4{ Te6edf3name Tff7b72-Tff7b72>

T8b949e// Escape the name in case it contains regex metacharacters (e.g. __video).

Tff7b72val Te6edf3escaped Tff7b72= Te6edf3RegexTb4b4b4.Te6edf3escapeTb4b4b4(Te6edf3nameTb4b4b4)

T8b949e// Matches:

T8b949e// <name/>

T8b949e// <name attr="..."/>

T8b949e// <name attr='...'>...content...</name>

Te6edf3RegexTb4b4b4(Ta5d6ff"""Ta5d6ff(?s)<Tffd700$Te6edf3escapedTa5d6ff(?:Ta5d6ff\Ta5d6ffs[^>]*?)?/>|<Tffd700$Te6edf3escapedTa5d6ff(?:Ta5d6ff\Ta5d6ffs[^>]*?)?>.*?</Tffd700$Te6edf3escapedTa5d6ff>Ta5d6ff"""Tb4b4b4)

Tb4b4b4}

T8b949e/** Matches whitespace between tags: `> \n <` → `><`. */

Tff7b72private Tff7b72val Te6edf3INTER_TAG_WHITESPACE Tff7b72= Te6edf3RegexTb4b4b4(Ta5d6ff"""Ta5d6ff>Ta5d6ff\Ta5d6ffs+<Ta5d6ff"""Tb4b4b4)

T8b949e/** Collapse leading / trailing whitespace across the whole fragment. */

Tff7b72private Tff7b72val Te6edf3EDGE_WHITESPACE Tff7b72= Te6edf3RegexTb4b4b4(Ta5d6ff"""Ta5d6ff^Ta5d6ff\Ta5d6ffs+|Ta5d6ff\Ta5d6ffs+$Ta5d6ff"""Tb4b4b4)

T8b949e/**

* Strip bloat elements and normalize whitespace on an inner `<detail>` fragment.

*

* The input is assumed to be the concatenated children of `<detail>` — i.e., what

* [CoTXmlParser.extractDetailInnerXml] returns. It is NOT the full `<event>` or the `<detail>` wrapper itself.

*

* Returns an empty string if every element was stripped (so callers can treat "empty" and "nothing worth sending"

* uniformly).

*/

Tff7b72fun Td2a8ffstripTb4b4b4(Te6edf3detailInnerXmlTb4b4b4: Tffa657StringTb4b4b4)Tb4b4b4: Tffa657String Tb4b4b4{

Tff7b72if Tb4b4b4(Te6edf3detailInnerXmlTb4b4b4.Te6edf3isEmptyTb4b4b4(Tb4b4b4)Tb4b4b4) Tff7b72return Ta5d6ff"Ta5d6ff"

Tff7b72var Te6edf3result Tff7b72= Te6edf3detailInnerXml

Tff7b72for Tb4b4b4(Te6edf3pattern Tff7b72in Te6edf3STRIPPED_ELEMENT_PATTERNSTb4b4b4) Tb4b4b4{

Te6edf3result Tff7b72= Te6edf3patternTb4b4b4.Te6edf3replaceTb4b4b4(Te6edf3resultTb4b4b4, Ta5d6ff"Ta5d6ff"Tb4b4b4)

Tb4b4b4}

T8b949e// Collapse whitespace between remaining tags. Preserves whitespace inside

T8b949e// text nodes (e.g. <remarks>hello world</remarks>) because that whitespace

T8b949e// isn't bracketed by '>' and '<'.

Te6edf3result Tff7b72= Te6edf3INTER_TAG_WHITESPACETb4b4b4.Te6edf3replaceTb4b4b4(Te6edf3resultTb4b4b4, Ta5d6ff"Ta5d6ff><Ta5d6ff"Tb4b4b4)

Te6edf3result Tff7b72= Te6edf3EDGE_WHITESPACETb4b4b4.Te6edf3replaceTb4b4b4(Te6edf3resultTb4b4b4, Ta5d6ff"Ta5d6ff"Tb4b4b4)

Tff7b72return Te6edf3result

Tb4b4b4}

Tb4b4b4}