remix-utils-rt/build/server/honeypot.js

This package contains simple utility functions to use with [React Router](https://reactrouter.com/home).

import { decrypt, encrypt, randomString } from "../common/crypto.js";
/**
 * The error thrown when the Honeypot fails, meaning some automated bot filled
 * the form and the request is probably spam.
 */
export class SpamError extends Error {
    name = "SpamError";
}
const DEFAULT_NAME_FIELD_NAME = "name__confirm";
const DEFAULT_VALID_FROM_FIELD_NAME = "from__confirm";
/**
 * Module used to implement a Honeypot.
 * A Honeypot is a visually hidden input that is used to detect spam bots. This
 * field is expected to be left empty by users because they don't see it, but
 * bots will fill it falling in the honeypot trap.
 */
export class Honeypot {
    generatedEncryptionSeed = this.randomValue();
    config;
    constructor(config = {}) {
        this.config = config;
    }
    /**
     * Get the HoneypotInputProps to be used in your forms.
     * @param options The options for the input props.
     * @param options.validFromTimestamp Since when the timestamp is valid.
     * @returns The props to be used in the form.
     */
    async getInputProps({ validFromTimestamp = Date.now(), } = {}) {
        return {
            nameFieldName: this.nameFieldName,
            validFromFieldName: this.validFromFieldName,
            encryptedValidFrom: await this.encrypt(validFromTimestamp.toString()),
        };
    }
    async check(formData) {
        let nameFieldName = this.config.nameFieldName ?? DEFAULT_NAME_FIELD_NAME;
        if (this.config.randomizeNameFieldName) {
            let actualName = this.getRandomizedNameFieldName(nameFieldName, formData);
            if (actualName)
                nameFieldName = actualName;
        }
        if (!this.shouldCheckHoneypot(formData, nameFieldName))
            return;
        if (!formData.has(nameFieldName)) {
            throw new SpamError("Missing honeypot input");
        }
        let honeypotValue = formData.get(nameFieldName);
        if (honeypotValue !== "")
            throw new SpamError("Honeypot input not empty");
        if (!this.validFromFieldName)
            return;
        let validFrom = formData.get(this.validFromFieldName);
        if (!validFrom)
            throw new SpamError("Missing honeypot valid from input");
        let time = await this.decrypt(validFrom);
        if (!time)
            throw new SpamError("Invalid honeypot valid from input");
        if (!this.isValidTimeStamp(Number(time))) {
            throw new SpamError("Invalid honeypot valid from input");
        }
        if (this.isFuture(Number(time))) {
            throw new SpamError("Honeypot valid from is in future");
        }
    }
    get nameFieldName() {
        let fieldName = this.config.nameFieldName ?? DEFAULT_NAME_FIELD_NAME;
        if (!this.config.randomizeNameFieldName)
            return fieldName;
        return `${fieldName}_${this.randomValue()}`;
    }
    get validFromFieldName() {
        if (this.config.validFromFieldName === undefined) {
            return DEFAULT_VALID_FROM_FIELD_NAME;
        }
        return this.config.validFromFieldName;
    }
    get encryptionSeed() {
        return this.config.encryptionSeed ?? this.generatedEncryptionSeed;
    }
    getRandomizedNameFieldName(nameFieldName, formData) {
        for (let key of formData.keys()) {
            if (!key.startsWith(nameFieldName))
                continue;
            return key;
        }
    }
    shouldCheckHoneypot(formData, nameFieldName) {
        return (formData.has(nameFieldName) ||
            Boolean(this.validFromFieldName && formData.has(this.validFromFieldName)));
    }
    randomValue() {
        return randomString();
    }
    encrypt(value) {
        return encrypt(value, this.encryptionSeed);
    }
    decrypt(value) {
        return decrypt(value, this.encryptionSeed);
    }
    isFuture(timestamp) {
        return timestamp > Date.now();
    }
    isValidTimeStamp(timestampp) {
        if (Number.isNaN(timestampp))
            return false;
        if (timestampp <= 0)
            return false;
        if (timestampp >= Number.MAX_SAFE_INTEGER)
            return false;
        return true;
    }
}
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