rentgen/stolen-data-entry.ts

import { EventEmitter } from 'events';
import ExtendedRequest, { HAREntry } from './extended-request';

import {
    getshorthost,
    isBase64,
    isBase64JSON,
    isJSONObject,
    isURL,
    maskString,
    parseToObject,
    safeDecodeURIComponent,
} from './util';

export type Sources =
    | 'cookie'
    | 'pathname'
    | 'queryparams'
    | 'header'
    | 'request_body';

export const Classifications = <const>{
    id: 'Identyfikator internetowy',
    history: 'Część historii przeglądania',
    location: 'Informacje na temat mojego położenia',
};

const ID_PREVIEW_MAX_LENGTH = 20;
const MIN_COOKIE_LENGTH_FOR_AUTO_MARK = 15;

const id = (function* id() {
    let i = 0;
    while (true) {
        i++;
        yield i;
    }
})();

export type DecodingSchema = 'base64' | 'raw';

export class StolenDataEntry extends EventEmitter {
    public isIAB = false;
    public id: number;
    private marked = false;
    public classification: keyof typeof Classifications;
    public decoding_applied: DecodingSchema = 'raw';
    public decodings_available: DecodingSchema[] = ['raw'];

    constructor(
        public request: ExtendedRequest,
        public source: Sources,
        public name: string,
        public value: string
    ) {
        super();
        this.id = id.next().value as number;
        this.classification = this.classify();
        if (isBase64(value)) {
            this.decodings_available.push('base64');
        }
    }

    getPriority() {
        let priority = 0;
        priority += Math.min(this.value.length, 50);
        const url = new URL(this.request.originalURL);
        if (this.value.includes(url.host)) {
            priority += 100;
        }
        if (this.value.includes(url.pathname)) {
            priority += 100;
        }
        if (this.source === 'cookie') {
            priority += 200;
        }
        return priority;
    }

    get isMarked() {
        return this.marked;
    }

    hasValue(value: string) {
        return this.value === value;
    }

    static parseValue(value: unknown): string | Record<string, unknown> {
        if (isBase64JSON(value)) {
            return StolenDataEntry.parseValue({
                base64: JSON.parse(atob(value)),
            });
        }
        if (value === undefined) {
            return '';
        }
        if (isJSONObject(value)) {
            const object = parseToObject(value);
            return object;
        } else if (isURL(value)) {
            const url = new URL(value);
            let hash = url.hash;
            if (hash.includes('=')) {
                //facebook sometimes includes querystring-encoded data into the hash... attempt to parse it
                try {
                    hash = Object.fromEntries(
                        hash
                            .slice(1)
                            .split('&')
                            .map((kv) => kv.split('='))
                    );
                } catch (e) {
                    // failed to parse as query string
                    console.log(
                        'Failed attempt to parse hash location as query string, probably safe to ignore:',
                        e
                    );
                }
            }
            const searchParams = Object.fromEntries(
                (
                    url.searchParams as unknown as {
                        entries: () => Iterable<[string, string]>;
                    }
                ).entries()
            );
            if (
                typeof hash !== 'object' &&
                Object.keys(searchParams).length === 0
            ) {
                return value; // just a string;
            }
            const object = {
                [Symbol.for('originalString')]: value, // so it doesn't appear raw in the table but can be easily retrieved later
                host: url.host,
                path: url.pathname,
                searchParams,
                ...(hash === ''
                    ? {}
                    : typeof hash === 'string'
                    ? { hash }
                    : hash),
            };
            return object;
        } else if (value === null) {
            return 'null';
        } else {
            return value.toString();
        }
    }

    getParsedValue(
        key_path: string
    ): string | Record<string | symbol, unknown> {
        let object = StolenDataEntry.parseValue(this.value);
        for (const key of key_path.split('.')) {
            if (key === '') continue;
            if (typeof key === 'string') {
                throw new Error(
                    'something went wrong when parsing ' + key_path
                );
            }
            object = StolenDataEntry.parseValue(object[key]);
        }
        return object;
    }

    mark() {
        const had_been_marked_before = this.marked;
        this.marked = true;
        if (!had_been_marked_before) {
            this.emit('change');
        }
    }

    unmark() {
        const had_been_marked_before = this.marked;
        this.marked = false;
        if (had_been_marked_before) {
            this.emit('change');
        }
    }

    toggleMark() {
        if (this.marked) {
            this.unmark();
        } else {
            this.mark();
        }
    }

    private classify(): keyof typeof Classifications {
        let result: keyof typeof Classifications;
        if (this.exposesOrigin()) {
            result = 'history';
        } else {
            result = 'id';
        }
        return result;
    }

    isRelatedToID() {
        return this.request.stolenData.some(
            (entry) => entry.classification == 'id'
        );
    }

    matchesHAREntry(har: HAREntry): boolean {
        return this.request.matchesHAREntry(har);
    }

    getValuePreview(key = ''): string {
        const value = this.getParsedValue(key);
        const str =
            typeof value === 'object' && value[Symbol.for('originalString')]
                ? (value[Symbol.for('originalString')] as string)
                : value.toString();
        if (typeof value !== 'object' && this.classification == 'id') {
            return maskString(value, 1 / 3, ID_PREVIEW_MAX_LENGTH);
        } else if (
            typeof value === 'object' &&
            value[Symbol.for('originalString')]
        ) {
            return value[Symbol.for('originalString')] as string;
        } else {
            return str;
        }
    }

    getUniqueKey() {
        return this.request.shorthost + ';' + this.name + ';' + this.value;
    }

    exposesOrigin(): boolean {
        return this.exposesHost() || this.exposesPath();
    }

    autoMark() {
        if (
            this.classification == 'history' ||
            ((this.source === 'cookie' ||
                this.name.toLowerCase().includes('id') ||
                this.name.toLowerCase().includes('cookie') ||
                this.name.toLowerCase().includes('ga') ||
                this.name.toLowerCase().includes('ses') ||
                this.name.toLowerCase().includes('fb')) &&
                this.value.length > MIN_COOKIE_LENGTH_FOR_AUTO_MARK)
        ) {
            if (
                (this.request.shorthost.includes('google') ||
                    this.request.shorthost.includes('youtube')) &&
                this.name == 'CONSENT'
            ) {
                // this cookie contains "YES" and might distract the person looking at it into thinking i gave consent on the reported site
                return;
            }
            this.mark();
        }
    }

    exposesPath() {
        return (
            this.request.originalPathname !== '/' &&
            [this.value, safeDecodeURIComponent(this.value)].some((haystack) =>
                haystack.includes(this.request.originalPathname)
            )
        );
    }

    exposesHost() {
        return [this.value, safeDecodeURIComponent(this.value)].some(
            (haystack) => haystack.includes(getshorthost(this.request.origin))
        );
    }
}