diff options
Diffstat (limited to '')
| -rw-r--r-- | toolkit/actors/ContentMetaChild.sys.mjs | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/toolkit/actors/ContentMetaChild.sys.mjs b/toolkit/actors/ContentMetaChild.sys.mjs new file mode 100644 index 0000000000..929d92db47 --- /dev/null +++ b/toolkit/actors/ContentMetaChild.sys.mjs @@ -0,0 +1,199 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +// Debounce time in milliseconds - this should be long enough to account for +// sync script tags that could appear between desired meta tags +const TIMEOUT_DELAY = 1000; + +const ACCEPTED_PROTOCOLS = ["http:", "https:"]; + +// Possible description tags, listed in order from least favourable to most favourable +const DESCRIPTION_RULES = [ + "twitter:description", + "description", + "og:description", +]; + +// Possible image tags, listed in order from least favourable to most favourable +const PREVIEW_IMAGE_RULES = [ + "thumbnail", + "twitter:image", + "og:image", + "og:image:url", + "og:image:secure_url", +]; + +/* + * Checks if the incoming meta tag has a greater score than the current best + * score by checking the index of the meta tag in the list of rules provided. + * + * @param {Array} aRules + * The list of rules for a given type of meta tag + * @param {String} aTag + * The name or property of the incoming meta tag + * @param {String} aEntry + * The current best entry for the given meta tag + * + * @returns {Boolean} true if the incoming meta tag is better than the current + * best meta tag of that same kind, false otherwise + */ +function shouldExtractMetadata(aRules, aTag, aEntry) { + return aRules.indexOf(aTag) > aEntry.currMaxScore; +} + +/* + * Ensure that the preview image URL is safe and valid before storing + * + * @param {URL} aURL + * A URL object that needs to be checked for valid principal and protocol + * + * @returns {Boolean} true if the preview URL is safe and can be stored, false otherwise + */ +function checkLoadURIStr(aURL) { + if (!ACCEPTED_PROTOCOLS.includes(aURL.protocol)) { + return false; + } + try { + let ssm = Services.scriptSecurityManager; + let principal = ssm.createNullPrincipal({}); + ssm.checkLoadURIStrWithPrincipal( + principal, + aURL.href, + ssm.DISALLOW_INHERIT_PRINCIPAL + ); + } catch (e) { + return false; + } + return true; +} + +/* + * This listens to DOMMetaAdded events and collects relevant metadata about the + * meta tag received. Then, it sends the metadata gathered from the meta tags + * and the url of the page as it's payload to be inserted into moz_places. + */ +export class ContentMetaChild extends JSWindowActorChild { + constructor() { + super(); + + // Store a mapping of the best description and preview + // image collected so far for a given URL. + this.metaTags = new Map(); + } + + didDestroy() { + for (let entry of this.metaTags.values()) { + entry.timeout.cancel(); + } + } + + handleEvent(event) { + switch (event.type) { + case "DOMContentLoaded": + const metaTags = this.contentWindow.document.querySelectorAll("meta"); + for (let metaTag of metaTags) { + this.onMetaTag(metaTag); + } + break; + case "DOMMetaAdded": + this.onMetaTag(event.originalTarget); + break; + default: + } + } + + onMetaTag(metaTag) { + const window = metaTag.ownerGlobal; + + // If there's no meta tag, ignore this. Also verify that the window + // matches just to be safe. + if (!metaTag || !metaTag.ownerDocument || window != this.contentWindow) { + return; + } + + const url = metaTag.ownerDocument.documentURI; + + let name = metaTag.name; + let prop = metaTag.getAttributeNS(null, "property"); + if (!name && !prop) { + return; + } + + let tag = name || prop; + + const entry = this.metaTags.get(url) || { + description: { value: null, currMaxScore: -1 }, + image: { value: null, currMaxScore: -1 }, + timeout: null, + }; + + // Malformed meta tag - do not store it + const content = metaTag.getAttributeNS(null, "content"); + if (!content) { + return; + } + + if (shouldExtractMetadata(DESCRIPTION_RULES, tag, entry.description)) { + // Extract the description + entry.description.value = content; + entry.description.currMaxScore = DESCRIPTION_RULES.indexOf(tag); + } else if (shouldExtractMetadata(PREVIEW_IMAGE_RULES, tag, entry.image)) { + // Extract the preview image + let value; + try { + value = new URL(content, url); + } catch (e) { + return; + } + if (value && checkLoadURIStr(value)) { + entry.image.value = value.href; + entry.image.currMaxScore = PREVIEW_IMAGE_RULES.indexOf(tag); + } + } else { + // We don't care about other meta tags + return; + } + + if (!this.metaTags.has(url)) { + this.metaTags.set(url, entry); + } + + if (entry.timeout) { + entry.timeout.delay = TIMEOUT_DELAY; + } else { + // We want to debounce incoming meta tags until we're certain we have the + // best one for description and preview image, and only store that one + entry.timeout = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer); + entry.timeout.initWithCallback( + () => { + entry.timeout = null; + this.metaTags.delete(url); + // We try to cancel the timers when we get destroyed, but if + // there's a race, catch it: + if (!this.manager || this.manager.isClosed) { + return; + } + + // Save description and preview image to moz_places + this.sendAsyncMessage("Meta:SetPageInfo", { + url, + description: entry.description.value, + previewImageURL: entry.image.value, + }); + + // Telemetry for recording the size of page metadata + let metadataSize = entry.description.value + ? entry.description.value.length + : 0; + metadataSize += entry.image.value ? entry.image.value.length : 0; + Services.telemetry + .getHistogramById("PAGE_METADATA_SIZE") + .add(metadataSize); + }, + TIMEOUT_DELAY, + Ci.nsITimer.TYPE_ONE_SHOT + ); + } + } +} |