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index.js
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index.js
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/**
* index.js
*
* a request API compatible with window.fetch
*
* All spec algorithm step numbers are based on https://fetch.spec.whatwg.org/commit-snapshots/ae716822cb3a61843226cd090eefc6589446c1d2/.
*/
import Url from 'url';
import http from 'http';
import https from 'https';
import zlib from 'zlib';
import Stream from 'stream';
import Body, { writeToStream, getTotalBytes } from './body';
import Response from './response';
import Headers, { createHeadersLenient } from './headers';
import Request, { getNodeRequestOptions } from './request';
import FetchError from './fetch-error';
import AbortError from './abort-error';
// fix an issue where "PassThrough", "resolve" aren't a named export for node <10
const PassThrough = Stream.PassThrough;
const resolve_url = Url.resolve;
/**
* Fetch function
*
* @param Mixed url Absolute url or Request instance
* @param Object opts Fetch options
* @return Promise
*/
export default function fetch(url, opts) {
// allow custom promise
if (!fetch.Promise) {
throw new Error('native promise missing, set fetch.Promise to your favorite alternative');
}
Body.Promise = fetch.Promise;
// wrap http.request into fetch
return new fetch.Promise((resolve, reject) => {
// build request object
const request = new Request(url, opts);
const options = getNodeRequestOptions(request);
const send = (options.protocol === 'https:' ? https : http).request;
const { signal } = request;
let response = null;
const abort = () => {
let error = new AbortError('The user aborted a request.');
reject(error);
if (request.body && request.body instanceof Stream.Readable) {
request.body.destroy(error);
}
if (!response || !response.body) return;
response.body.emit('error', error);
}
if (signal && signal.aborted) {
abort();
return;
}
const abortAndFinalize = () => {
abort();
finalize();
}
// send request
const req = send(options);
let reqTimeout;
if (signal) {
signal.addEventListener('abort', abortAndFinalize);
}
function finalize() {
req.abort();
if (signal) signal.removeEventListener('abort', abortAndFinalize);
clearTimeout(reqTimeout);
}
if (request.timeout) {
req.once('socket', socket => {
reqTimeout = setTimeout(() => {
reject(new FetchError(`network timeout at: ${request.url}`, 'request-timeout'));
finalize();
}, request.timeout);
});
}
req.on('error', err => {
reject(new FetchError(`request to ${request.url} failed, reason: ${err.message}`, 'system', err));
finalize();
});
req.on('response', res => {
clearTimeout(reqTimeout);
const headers = createHeadersLenient(res.headers);
// HTTP fetch step 5
if (fetch.isRedirect(res.statusCode)) {
// HTTP fetch step 5.2
const location = headers.get('Location');
// HTTP fetch step 5.3
const locationURL = location === null ? null : resolve_url(request.url, location);
// HTTP fetch step 5.5
switch (request.redirect) {
case 'error':
reject(new FetchError(`redirect mode is set to error: ${request.url}`, 'no-redirect'));
finalize();
return;
case 'manual':
// node-fetch-specific step: make manual redirect a bit easier to use by setting the Location header value to the resolved URL.
if (locationURL !== null) {
// handle corrupted header
try {
headers.set('Location', locationURL);
} catch (err) {
// istanbul ignore next: nodejs server prevent invalid response headers, we can't test this through normal request
reject(err);
}
}
break;
case 'follow':
// HTTP-redirect fetch step 2
if (locationURL === null) {
break;
}
// HTTP-redirect fetch step 5
if (request.counter >= request.follow) {
reject(new FetchError(`maximum redirect reached at: ${request.url}`, 'max-redirect'));
finalize();
return;
}
// HTTP-redirect fetch step 6 (counter increment)
// Create a new Request object.
const requestOpts = {
headers: new Headers(request.headers),
follow: request.follow,
counter: request.counter + 1,
agent: request.agent,
compress: request.compress,
method: request.method,
body: request.body,
signal: request.signal,
timeout: request.timeout
};
// HTTP-redirect fetch step 9
if (res.statusCode !== 303 && request.body && getTotalBytes(request) === null) {
reject(new FetchError('Cannot follow redirect with body being a readable stream', 'unsupported-redirect'));
finalize();
return;
}
// HTTP-redirect fetch step 11
if (res.statusCode === 303 || ((res.statusCode === 301 || res.statusCode === 302) && request.method === 'POST')) {
requestOpts.method = 'GET';
requestOpts.body = undefined;
requestOpts.headers.delete('content-length');
}
// HTTP-redirect fetch step 15
resolve(fetch(new Request(locationURL, requestOpts)));
finalize();
return;
}
}
// prepare response
res.once('end', () => {
if (signal) signal.removeEventListener('abort', abortAndFinalize);
});
let body = res.pipe(new PassThrough());
const response_options = {
url: request.url,
status: res.statusCode,
statusText: res.statusMessage,
headers: headers,
size: request.size,
timeout: request.timeout
};
// HTTP-network fetch step 12.1.1.3
const codings = headers.get('Content-Encoding');
// HTTP-network fetch step 12.1.1.4: handle content codings
// in following scenarios we ignore compression support
// 1. compression support is disabled
// 2. HEAD request
// 3. no Content-Encoding header
// 4. no content response (204)
// 5. content not modified response (304)
if (!request.compress || request.method === 'HEAD' || codings === null || res.statusCode === 204 || res.statusCode === 304) {
response = new Response(body, response_options);
resolve(response);
return;
}
// For Node v6+
// Be less strict when decoding compressed responses, since sometimes
// servers send slightly invalid responses that are still accepted
// by common browsers.
// Always using Z_SYNC_FLUSH is what cURL does.
const zlibOptions = {
flush: zlib.Z_SYNC_FLUSH,
finishFlush: zlib.Z_SYNC_FLUSH
};
// for gzip
if (codings == 'gzip' || codings == 'x-gzip') {
body = body.pipe(zlib.createGunzip(zlibOptions));
response = new Response(body, response_options);
resolve(response);
return;
}
// for deflate
if (codings == 'deflate' || codings == 'x-deflate') {
// handle the infamous raw deflate response from old servers
// a hack for old IIS and Apache servers
const raw = res.pipe(new PassThrough());
raw.once('data', chunk => {
// see http://stackoverflow.com/questions/37519828
if ((chunk[0] & 0x0F) === 0x08) {
body = body.pipe(zlib.createInflate());
} else {
body = body.pipe(zlib.createInflateRaw());
}
response = new Response(body, response_options);
resolve(response);
});
return;
}
// for br
if (codings == 'br' && typeof zlib.createBrotliDecompress === 'function') {
body = body.pipe(zlib.createBrotliDecompress());
response = new Response(body, response_options);
resolve(response);
return;
}
// otherwise, use response as-is
response = new Response(body, response_options);
resolve(response);
});
writeToStream(req, request);
});
};
/**
* Redirect code matching
*
* @param Number code Status code
* @return Boolean
*/
fetch.isRedirect = code => code === 301 || code === 302 || code === 303 || code === 307 || code === 308;
// expose Promise
fetch.Promise = global.Promise;
export {
Headers,
Request,
Response,
FetchError
};