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service-worker: checking for plugin constructors availability after retrieving config.json using non-fetch means now also dives into dependencies (ref. #48)

merge-requests/23/merge
Michał 'rysiek' Woźniak 2024-01-28 22:56:25 +00:00
rodzic 707ce71102
commit b159976478
1 zmienionych plików z 47 dodań i 25 usunięć
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72
service-worker.js
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@ -342,8 +342,14 @@ let initServiceWorker = async () => {
// first let's deal with the easy part -- do we want to use MIME type guessing based on content?
if (self.LibResilientConfig.useMimeSniffingLibrary === true) {
// we do! load the external lib
self.importScripts(`./lib/file-type.js`)
// we do not want to hit a NetworkError and end up using the default config
// much better to end up not using the fancy MIME type detection in such a case
try {
// we do! load the external lib
self.importScripts(`./lib/file-type.js`)
} catch (e) {
self.log('service-worker', `error when fetching external MIME sniffing library: ${e.message}`)
}
if (typeof fileType !== 'undefined' && "fileTypeFromBuffer" in fileType) {
detectMimeFromBuffer = fileType.fileTypeFromBuffer
self.log('service-worker', 'loaded external MIME sniffing library')
@ -479,30 +485,46 @@ let initServiceWorker = async () => {
// if we got the new config.json via a method *other* than plain old fetch(),
// we will not be able to use importScripts() to load any pugins that have not been loaded already
//
// NOTICE: this *only* checks if we have all the necessary plugin constructors already available
// which signifies that relevant code has been successfully loaded; but there are other failure modes!
if (cresponse.headers.get('x-libresilient-method') != 'fetch') {
// go through the plugins in the new config and check if we already have their constructors
// i.e. if the plugin scripts have already been loaded
// FIXME: this does not currently dive into dependencies!
// FIXME: https://gitlab.com/rysiekpl/libresilient/-/issues/48
for (let p in cdata.plugins) {
var pname = cdata.plugins[p].name
// plugin constructor not available, meaning: we'd have to importScripts() it
// but we can't since this was not retrieved via fetch(), so we cannot assume
// that the main domain of the website is up and available
//
// if we cache this newly retrieved config.json, next time the service worker gets restarted
// we will end up with an error while trying to run importScripts() for this plugin
// which in turn would lead to the service worker being unregistered
//
// if the main domain is not available, this would mean the website stops working
// even though we *were* able to retrieve the new config.json via plugins!
// so, ignoring this new config.json.
if (!LibResilientPluginConstructors.has(pname)) {
self.log('service-worker', `config.json was retrieved through plugins other than fetch, but specifies additional plugins (${pname}); ignoring.`)
return false;
}
try {
// go through the plugins in the new config and check if we already have their constructors
// i.e. if the plugin scripts have already been loaded
let plugins = [...cdata.plugins]
let currentPlugin = plugins.shift()
do {
// plugin constructor not available, meaning: we'd have to importScripts() it
// but we can't since this was not retrieved via fetch(), so we cannot assume
// that the main domain of the website is up and available
//
// if we cache this newly retrieved config.json, next time the service worker gets restarted
// we will end up with an error while trying to run importScripts() for this plugin
// which in turn would lead to the service worker being unregistered
//
// if the main domain is not available, this would mean the website stops working
// even though we *were* able to retrieve the new config.json via plugins!
// so, ignoring this new config.json.
if (!LibResilientPluginConstructors.has(currentPlugin.name)) {
throw new Error(`config.json loaded through transport other than fetch, but specifies not previously loaded plugin: "${currentPlugin.name}"`)
}
// push any dependencies into the array, at the very front
// thus gradually flattening the config
if ("uses" in currentPlugin) {
plugins.unshift(...currentPlugin.uses)
}
// get the next plugin to check
currentPlugin = plugins.shift()
} while ( (currentPlugin !== false) && (currentPlugin !== undefined) )
} catch(e) {
self.log(
'service-worker',
`warning: ${e.message}\nignoring the whole config.json.`)
return false;
}
}
@ -517,7 +539,7 @@ let initServiceWorker = async () => {
// we only get a cryptic "Error while registering a service worker"
// unless we explicitly print the errors out in the console
console.error(e)
// we got an error while initializing the plugins
// we got an error while initializing the service worker!
// better play it safe!
self.registration.unregister()
throw e