got/dist/source/core/parse-link-header.js

Human-friendly and powerful HTTP request library for Node.js

const splitHeaderValue = (value, separator) => {
    const values = [];
    let current = '';
    let inQuotes = false;
    let inReference = false;
    let isEscaped = false;
    for (const character of value) {
        if (inQuotes && isEscaped) {
            current += character;
            isEscaped = false;
            continue;
        }
        if (inQuotes && character === '\\') {
            current += character;
            isEscaped = true;
            continue;
        }
        if (character === '"') {
            inQuotes = !inQuotes;
            current += character;
            continue;
        }
        if (!inQuotes && character === '<') {
            inReference = true;
            current += character;
            continue;
        }
        if (!inQuotes && character === '>') {
            inReference = false;
            current += character;
            continue;
        }
        // Link headers use both quoted strings and <URI-reference> values, so raw
        // splitting on `,` / `;` would break valid values containing those characters.
        if (!inQuotes && !inReference && character === separator) {
            values.push(current);
            current = '';
            continue;
        }
        current += character;
    }
    if (inQuotes || isEscaped) {
        throw new Error(`Failed to parse Link header: ${value}`);
    }
    values.push(current);
    return values;
};
export default function parseLinkHeader(link) {
    const parsed = [];
    const items = splitHeaderValue(link, ',');
    for (const item of items) {
        // https://tools.ietf.org/html/rfc5988#section-5
        const [rawUriReference, ...rawLinkParameters] = splitHeaderValue(item, ';');
        const trimmedUriReference = rawUriReference.trim();
        // eslint-disable-next-line @typescript-eslint/prefer-string-starts-ends-with
        if (trimmedUriReference[0] !== '<' || trimmedUriReference.at(-1) !== '>') {
            throw new Error(`Invalid format of the Link header reference: ${trimmedUriReference}`);
        }
        const reference = trimmedUriReference.slice(1, -1);
        const parameters = {};
        if (reference.includes('<') || reference.includes('>')) {
            throw new Error(`Invalid format of the Link header reference: ${trimmedUriReference}`);
        }
        if (rawLinkParameters.length === 0) {
            throw new Error(`Unexpected end of Link header parameters: ${rawLinkParameters.join(';')}`);
        }
        for (const rawParameter of rawLinkParameters) {
            const trimmedRawParameter = rawParameter.trim();
            const center = trimmedRawParameter.indexOf('=');
            if (center === -1) {
                throw new Error(`Failed to parse Link header: ${link}`);
            }
            const name = trimmedRawParameter.slice(0, center).trim();
            const value = trimmedRawParameter.slice(center + 1).trim();
            parameters[name] = value;
        }
        parsed.push({
            reference,
            parameters,
        });
    }
    return parsed;
}