1. Request Validator

function validateRequest(obj) {
    const keyArr = ['method', 'uri', 'version', 'message'];
    const printArr = ['Method', 'URI', 'Version', 'Message']
    const methodArr = ['GET', 'POST', 'DELETE', 'CONNECT'];
    const uriRegex = /^([\w.]+)$/gm;
    const versionArr = ['HTTP/0.9', 'HTTP/1.0', 'HTTP/1.1', 'HTTP/2.0'];
    const messageRegex = /^([^<>\\&'"]+)$/gm;
    let funcArr = [checkMethod, checkUri, checkVersion, checkMessage];
    let counter = 0;
    let inputKeys = Object.keys(obj);

    for (let i = 0; i < keyArr.length; i++) {
        let keyValPairCheck = funcArr[i](inputKeys[i], obj[inputKeys[i]]);

        if (inputKeys.indexOf(keyArr[i]) === -1 || !keyValPairCheck) {
            throw new Error(`Invalid request header: Invalid ${printArr[i]}`);
        } else {
            counter++
        }
    }

    if (counter === 4) {
        return obj;
    }

    function checkMethod(key, val) {
        return keyArr.indexOf(key) != -1 && methodArr.indexOf(val) != -1;
    };
    function checkUri(key, val) {
        return keyArr.indexOf(key) != -1 && (uriRegex.test(val) || val === '*');
    };
    function checkVersion(key, val) {
        return keyArr.indexOf(key) != -1 && versionArr.indexOf(val) != -1;
    };
    function checkMessage(key, val) {
        return keyArr.indexOf(key) != -1 && (messageRegex.test(val) || val === '');
    };
}