dkim-verifier/header.js

DKIM Signature Verifier in TypeScript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.getNonSignatureDkim = exports.getSignature = exports.parseDkim = void 0;
const canonicalization_1 = require("./canonicalization");
const parseDkim = (headers) => {
    const dkimParams = dkimKeyAndValue(headers);
    const dkim = {
        v: "",
        a: "",
        b: "",
        bh: "",
        d: "",
        h: "",
        s: "",
    };
    for (const [key, value] of dkimParams) {
        dkim[key] = value;
    }
    return dkim;
};
exports.parseDkim = parseDkim;
const getSignature = (dkim) => {
    const bufferSignature = Buffer.from(dkim.b, "base64");
    return BigInt(`0x${bufferSignature.toString("hex")}`);
};
exports.getSignature = getSignature;
const getNonSignatureDkim = (headers) => {
    const dkimParams = dkimKeyAndValue(headers);
    let nonSignatureDkim = "dkim-signature:";
    for (const [key, value] of dkimParams) {
        nonSignatureDkim += `${key}=${key === "b" ? "" : value}; `;
    }
    return nonSignatureDkim.slice(0, -2);
};
exports.getNonSignatureDkim = getNonSignatureDkim;
const dkimKeyAndValue = (headers) => {
    const DkimParams = headers.find((header) => header.key.toLowerCase() === "dkim-signature");
    if (!DkimParams) {
        throw new Error("DKIM header not found");
    }
    const dkimParams = DkimParams.value.split(";");
    const dkimKeyAndValue = [];
    for (let dkimParam of dkimParams) {
        dkimParam = (0, canonicalization_1.relaxedHeader)(dkimParam);
        const key = dkimParam.split("=")[0];
        let value = dkimParam.slice(key.length + 1, dkimParam.length);
        if (key === "b")
            value = value.replace(/\s/g, "");
        dkimKeyAndValue.push([key, value]);
    }
    return dkimKeyAndValue;
};
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