@helia/verified-fetch/dist/src/utils/response-headers.js

A fetch-like API for obtaining verified & trustless IPFS content on the web

import { InvalidRangeError } from '../errors.js';
/**
 * Implementations may place an upper bound on any TTL received, as noted in Section 8 of [rfc2181].
 * If TTL value is unknown, implementations should not send a Cache-Control
 * No matter if TTL value is known or not, implementations should always send a Last-Modified header with the timestamp of the record resolution.
 *
 * @see https://specs.ipfs.tech/http-gateways/path-gateway/#cache-control-response-header
 */
export function setCacheControlHeader({ ttl, protocol, response }) {
    if (response.headers.has('cache-control')) {
        // don't set the header if it's already set by a plugin
        return;
    }
    let headerValue;
    if (protocol === 'ipfs:') {
        headerValue = 'public, max-age=29030400, immutable';
    }
    else if (ttl == null) {
        /**
         * default limit for unknown TTL: "use 5 minute as default fallback when it is not available."
         *
         * @see https://github.com/ipfs/boxo/issues/329#issuecomment-1995236409
         */
        headerValue = 'public, max-age=300';
    }
    else {
        headerValue = `public, max-age=${ttl}`;
    }
    response.headers.set('cache-control', headerValue);
}
/**
 * This function returns the value of the `Content-Range` header for a given
 * range.
 *
 * If you know the total size of the body, pass it as `byteSize`
 *
 * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Range
 */
export function getContentRangeHeader(byteSize, byteStart, byteEnd) {
    if (byteStart != null) {
        byteStart = BigInt(byteStart);
    }
    if (byteEnd != null) {
        byteEnd = BigInt(byteEnd);
    }
    // if we don't know the total size, we should use *
    const total = BigInt(byteSize);
    // validate start/end are not outside total size
    if ((byteEnd ?? 0n) >= total) {
        throw new InvalidRangeError('Invalid range: Range-end index is greater than or equal to the size of the file.');
    }
    if ((byteStart ?? 0n) >= total) {
        throw new InvalidRangeError('Invalid range: Range-start index is greater than or equal to the size of the file.');
    }
    let range = '*';
    if (byteStart == null) {
        if (byteEnd != null) {
            if (byteEnd < 0n) {
                range = `${total + byteEnd}-${total - 1n}`;
            }
            else {
                range = `0-${byteEnd}`;
            }
        }
    }
    else {
        if (byteEnd == null) {
            let end = '*';
            if (byteSize != null) {
                end = `${total - 1n}`;
            }
            range = `${byteStart}-${end}`;
        }
        else {
            range = `${byteStart}-${byteEnd}`;
        }
    }
    return `bytes ${range}/${total}`;
}
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