out-of-your-element/m2d/converters/utils.js

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// @ts-check
const reg = require("../../matrix/read-registration")
const userRegex = reg.namespaces.users.map(u => new RegExp(u.regex))
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const assert = require("assert").strict
/** @type {import("xxhash-wasm").XXHashAPI} */ // @ts-ignore
let hasher = null
// @ts-ignore
require("xxhash-wasm")().then(h => hasher = h)
const BLOCK_ELEMENTS = [
"ADDRESS", "ARTICLE", "ASIDE", "AUDIO", "BLOCKQUOTE", "BODY", "CANVAS",
"CENTER", "DD", "DETAILS", "DIR", "DIV", "DL", "DT", "FIELDSET", "FIGCAPTION", "FIGURE",
"FOOTER", "FORM", "FRAMESET", "H1", "H2", "H3", "H4", "H5", "H6", "HEADER",
"HGROUP", "HR", "HTML", "ISINDEX", "LI", "MAIN", "MENU", "NAV", "NOFRAMES",
"NOSCRIPT", "OL", "OUTPUT", "P", "PRE", "SECTION", "SUMMARY", "TABLE", "TBODY", "TD",
"TFOOT", "TH", "THEAD", "TR", "UL"
]
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const NEWLINE_ELEMENTS = BLOCK_ELEMENTS.concat(["BR"])
/**
* Determine whether an event is the bridged representation of a discord message.
* Such messages shouldn't be bridged again.
* @param {string} sender
*/
function eventSenderIsFromDiscord(sender) {
// If it's from a user in the bridge's namespace, then it originated from discord
// This includes messages sent by the appservice's bot user, because that is what's used for webhooks
// TODO: It would be nice if bridge system messages wouldn't trigger this check and could be bridged from matrix to discord, while webhook reflections would remain ignored...
// TODO that only applies to the above todo: But you'd have to watch out for the /icon command, where the bridge bot would set the room avatar, and that shouldn't be reflected into the room a second time.
if (userRegex.some(x => sender.match(x))) {
return true
}
return false
}
/**
* @param {string} mxc
* @returns {string?}
*/
function getPublicUrlForMxc(mxc) {
const avatarURLParts = mxc?.match(/^mxc:\/\/([^/]+)\/(\w+)$/)
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if (avatarURLParts) return `${reg.ooye.server_origin}/_matrix/media/r0/download/${avatarURLParts[1]}/${avatarURLParts[2]}`
else return null
}
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/**
* Event IDs are really big and have more entropy than we need.
* If we want to store the event ID in the database, we can store a more compact version by hashing it with this.
* I choose a 64-bit non-cryptographic hash as only a 32-bit hash will see birthday collisions unreasonably frequently: https://en.wikipedia.org/wiki/Birthday_attack#Mathematics
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* xxhash outputs an unsigned 64-bit integer.
* Converting to a signed 64-bit integer with no bit loss so that it can be stored in an SQLite integer field as-is: https://www.sqlite.org/fileformat2.html#record_format
* This should give very efficient storage with sufficient entropy.
* @param {string} eventID
*/
function getEventIDHash(eventID) {
assert(hasher, "xxhash is not ready yet")
if (eventID[0] === "$" && eventID.length >= 13) {
eventID = eventID.slice(1) // increase entropy per character to potentially help xxhash
}
const unsignedHash = hasher.h64(eventID)
const signedHash = unsignedHash - 0x8000000000000000n // shifting down to signed 64-bit range
return signedHash
}
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class MatrixStringBuilder {
constructor() {
this.body = ""
this.formattedBody = ""
}
/**
* @param {string} body
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* @param {string} [formattedBody]
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* @param {any} [condition]
*/
add(body, formattedBody, condition = true) {
if (condition) {
if (formattedBody == undefined) formattedBody = body
this.body += body
this.formattedBody += formattedBody
}
return this
}
/**
* @param {string} body
* @param {string} [formattedBody]
* @param {any} [condition]
*/
addLine(body, formattedBody, condition = true) {
if (condition) {
if (formattedBody == undefined) formattedBody = body
if (this.body.length && this.body.slice(-1) !== "\n") this.body += "\n"
this.body += body
const match = this.formattedBody.match(/<\/?([a-zA-Z]+[a-zA-Z0-9]*)[^>]*>\s*$/)
if (this.formattedBody.length && (!match || !NEWLINE_ELEMENTS.includes(match[1].toUpperCase()))) this.formattedBody += "<br>"
this.formattedBody += formattedBody
}
return this
}
/**
* @param {string} body
* @param {string} [formattedBody]
* @param {any} [condition]
*/
addParagraph(body, formattedBody, condition = true) {
if (condition) {
if (formattedBody == undefined) formattedBody = body
if (this.body.length && this.body.slice(-1) !== "\n") this.body += "\n\n"
this.body += body
formattedBody = `<p>${formattedBody}</p>`
this.formattedBody += formattedBody
}
return this
}
get() {
return {
msgtype: "m.text",
body: this.body,
format: "org.matrix.custom.html",
formatted_body: this.formattedBody
}
}
}
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/**
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* Context: Room IDs are not routable on their own. Room permalinks need a list of servers to try. The client is responsible for coming up with a list of servers.
* ASSUMPTION 1: The bridge bot is a member of the target room and can therefore access its power levels and member list for calculation.
* ASSUMPTION 2: Because the bridge bot is a member of the target room, the target room is bridged.
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* https://spec.matrix.org/v1.9/appendices/#routing
* https://gitdab.com/cadence/out-of-your-element/issues/11
* @param {string} roomID
* @param {{[K in "getStateEvent" | "getJoinedMembers"]: import("../../matrix/api")[K]}} api
*/
async function getViaServers(roomID, api) {
const candidates = []
const {joined} = await api.getJoinedMembers(roomID)
// Candidate 0: The bot's own server name
candidates.push(reg.ooye.server_name)
// Candidate 1: Highest joined non-sim non-bot power level user in the room
// https://github.com/matrix-org/matrix-react-sdk/blob/552c65db98b59406fb49562e537a2721c8505517/src/utils/permalinks/Permalinks.ts#L172
try {
/** @type {{users?: {[mxid: string]: number}}} */
const powerLevels = await api.getStateEvent(roomID, "m.room.power_levels", "")
if (powerLevels.users) {
const sorted = Object.entries(powerLevels.users).sort((a, b) => b[1] - a[1]) // Highest...
for (const power of sorted) {
const mxid = power[0]
if (!(mxid in joined)) continue // joined...
if (userRegex.some(r => mxid.match(r))) continue // non-sim non-bot...
const match = mxid.match(/:(.*)/)
assert(match)
if (!candidates.includes(match[1])) {
candidates.push(match[1])
break
}
}
}
} catch (e) {
// power levels event not found
}
// Candidates 2-3: Most popular servers in the room
/** @type {Map<string, number>} */
const servers = new Map()
// We can get the most popular servers if we know the members, so let's process those...
Object.keys(joined)
.filter(mxid => !mxid.startsWith("@_")) // Quick check
.filter(mxid => !userRegex.some(r => mxid.match(r))) // Full check
.slice(0, 1000) // Just sample the first thousand real members
.map(mxid => {
const match = mxid.match(/:(.*)/)
assert(match)
return match[1]
})
.filter(server => !server.match(/([a-f0-9:]+:+)+[a-f0-9]+/)) // No IPv6 servers
.filter(server => !server.match(/[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}/)) // No IPv4 servers
// I don't care enough to check ACLs
.forEach(server => {
const existing = servers.get(server)
if (!existing) servers.set(server, 1)
else servers.set(server, existing + 1)
})
const serverList = [...servers.entries()].sort((a, b) => b[1] - a[1])
for (const server of serverList) {
if (!candidates.includes(server[0])) {
candidates.push(server[0])
if (candidates.length >= 4) break // Can have at most 4 candidate via servers
}
}
return candidates
}
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/**
* Context: Room IDs are not routable on their own. Room permalinks need a list of servers to try. The client is responsible for coming up with a list of servers.
* ASSUMPTION 1: The bridge bot is a member of the target room and can therefore access its power levels and member list for calculation.
* ASSUMPTION 2: Because the bridge bot is a member of the target room, the target room is bridged.
* https://spec.matrix.org/v1.9/appendices/#routing
* https://gitdab.com/cadence/out-of-your-element/issues/11
* @param {string} roomID
* @param {{[K in "getStateEvent" | "getJoinedMembers"]: import("../../matrix/api")[K]}} api
* @returns {Promise<URLSearchParams>}
*/
async function getViaServersQuery(roomID, api) {
const list = await getViaServers(roomID, api)
const qs = new URLSearchParams()
for (const server of list) {
qs.append("via", server)
}
return qs
}
module.exports.BLOCK_ELEMENTS = BLOCK_ELEMENTS
module.exports.eventSenderIsFromDiscord = eventSenderIsFromDiscord
module.exports.getPublicUrlForMxc = getPublicUrlForMxc
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module.exports.getEventIDHash = getEventIDHash
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module.exports.MatrixStringBuilder = MatrixStringBuilder
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module.exports.getViaServers = getViaServers
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module.exports.getViaServersQuery = getViaServersQuery