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@ -7,12 +7,48 @@ import Foundation
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@objc
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public enum LinkPreviewError: Int, Error {
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case invalidInput
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case assertionFailure
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case noPreview
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}
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@objc(OWSLinkPreview)
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// MARK: - OWSLinkPreviewInfo
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// This contains the info for a link preview "draft".
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public class OWSLinkPreviewInfo: NSObject {
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@objc
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public var urlString: String
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@objc
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public var title: String?
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@objc
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public var imageFilePath: String?
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@objc
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public init(urlString: String, title: String?, imageFilePath: String? = nil) {
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self.urlString = urlString
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self.title = title
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self.imageFilePath = imageFilePath
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super.init()
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}
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fileprivate func isValid() -> Bool {
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var hasTitle = false
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if let titleValue = title {
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hasTitle = titleValue.count > 0
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}
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let hasImage = imageFilePath != nil
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return hasTitle || hasImage
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}
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}
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// MARK: - OWSLinkPreview
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@objc
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public class OWSLinkPreview: MTLModel {
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@objc
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public static let featureEnabled = true
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@objc
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public var urlString: String?
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@ -31,6 +67,11 @@ public class OWSLinkPreview: MTLModel {
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super.init()
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}
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@objc
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public override init() {
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super.init()
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}
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@objc
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public required init!(coder: NSCoder) {
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super.init(coder: coder)
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@ -53,6 +94,9 @@ public class OWSLinkPreview: MTLModel {
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public class func buildValidatedLinkPreview(dataMessage: SSKProtoDataMessage,
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body: String?,
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transaction: YapDatabaseReadWriteTransaction) throws -> OWSLinkPreview {
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guard OWSLinkPreview.featureEnabled else {
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throw LinkPreviewError.noPreview
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}
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guard let previewProto = dataMessage.preview else {
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throw LinkPreviewError.noPreview
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}
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@ -73,7 +117,11 @@ public class OWSLinkPreview: MTLModel {
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throw LinkPreviewError.invalidInput
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}
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// TODO: Verify that url host is in whitelist.
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guard isValidLinkUrl(urlString) else {
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Logger.verbose("Invalid link URL \(urlString).")
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Logger.error("Invalid link URL.")
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throw LinkPreviewError.invalidInput
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}
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let title: String? = previewProto.title?.trimmingCharacters(in: .whitespacesAndNewlines)
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@ -88,17 +136,70 @@ public class OWSLinkPreview: MTLModel {
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}
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}
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let linkPreview = OWSLinkPreview(urlString: urlString, title: title, imageAttachmentId: imageAttachmentId)
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guard linkPreview.isValid() else {
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owsFailDebug("Preview has neither title nor image.")
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throw LinkPreviewError.invalidInput
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}
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return linkPreview
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}
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@objc
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public class func buildValidatedLinkPreview(fromInfo info: OWSLinkPreviewInfo,
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transaction: YapDatabaseReadWriteTransaction) throws -> OWSLinkPreview {
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guard OWSLinkPreview.featureEnabled else {
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throw LinkPreviewError.noPreview
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}
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let imageAttachmentId = OWSLinkPreview.saveAttachmentIfPossible(forFilePath: info.imageFilePath,
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transaction: transaction)
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let linkPreview = OWSLinkPreview(urlString: info.urlString, title: info.title, imageAttachmentId: imageAttachmentId)
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guard linkPreview.isValid() else {
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owsFailDebug("Preview has neither title nor image.")
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throw LinkPreviewError.invalidInput
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}
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return linkPreview
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}
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private class func saveAttachmentIfPossible(forFilePath filePath: String?,
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transaction: YapDatabaseReadWriteTransaction) -> String? {
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guard let filePath = filePath else {
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return nil
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}
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guard let fileSize = OWSFileSystem.fileSize(ofPath: filePath) else {
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owsFailDebug("Unknown file size for path: \(filePath)")
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return nil
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}
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guard fileSize.uint32Value > 0 else {
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owsFailDebug("Invalid file size for path: \(filePath)")
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return nil
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}
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let filename = (filePath as NSString).lastPathComponent
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let fileExtension = (filename as NSString).pathExtension
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guard fileExtension.count > 0 else {
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owsFailDebug("Invalid file extension for path: \(filePath)")
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return nil
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}
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guard let contentType = MIMETypeUtil.mimeType(forFileExtension: fileExtension) else {
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owsFailDebug("Invalid content type for path: \(filePath)")
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return nil
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}
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let attachment = TSAttachmentStream(contentType: contentType, byteCount: fileSize.uint32Value, sourceFilename: nil, caption: nil, albumMessageId: nil)
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attachment.save(with: transaction)
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return attachment.uniqueId
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}
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private func isValid() -> Bool {
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var hasTitle = false
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if let titleValue = title {
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hasTitle = titleValue.count > 0
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}
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let hasImage = imageAttachmentId != nil
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if !hasTitle && !hasImage {
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Logger.error("Preview has neither title nor image.")
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throw LinkPreviewError.invalidInput
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}
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return OWSLinkPreview(urlString: urlString, title: title, imageAttachmentId: imageAttachmentId)
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return hasTitle || hasImage
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}
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@objc
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@ -117,20 +218,30 @@ public class OWSLinkPreview: MTLModel {
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// MARK: - Domain Whitelist
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private static let linkDomainWhitelist = [
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"youtube.com",
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"reddit.com",
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"imgur.com",
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"instagram.com"
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"youtube.com",
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"reddit.com",
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"imgur.com",
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"instagram.com"
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]
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private static let mediaDomainWhitelist = [
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"ytimg.com",
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"cdninstagram.com"
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]
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]
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private static let protocolWhitelist = [
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"https"
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]
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]
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// *.giphy.com
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// *.youtube.com
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// *.youtu.be
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// *.ytimg.com
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// *.reddit.com
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// *.reddi.it
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// *.imgur.com
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// *.instagram.com
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// *.cdninstagram.com
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@objc
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public class func isValidLinkUrl(_ urlString: String) -> Bool {
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@ -147,7 +258,7 @@ public class OWSLinkPreview: MTLModel {
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return false
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}
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return isUrlInDomainWhitelist(url: url,
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domainWhitelist: OWSLinkPreview.linkDomainWhitelist + OWSLinkPreview.mediaDomainWhitelist)
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domainWhitelist: OWSLinkPreview.linkDomainWhitelist + OWSLinkPreview.mediaDomainWhitelist)
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}
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private class func isUrlInDomainWhitelist(url: URL, domainWhitelist: [String]) -> Bool {
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@ -176,19 +287,257 @@ public class OWSLinkPreview: MTLModel {
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return false
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}
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// MARK: - Serial Queue
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private static let serialQueue = DispatchQueue(label: "org.signal.linkPreview")
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private class func assertIsOnSerialQueue() {
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if _isDebugAssertConfiguration(), #available(iOS 10.0, *) {
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assertOnQueue(serialQueue)
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}
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}
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// MARK: - Text Parsing
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@objc
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public class func previewUrl(forMessageBodyText body: String?) -> String? {
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// This cache should only be accessed on serialQueue.
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private static var previewUrlCache: NSCache<AnyObject, AnyObject> = NSCache()
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private class func previewUrl(forMessageBodyText body: String?) -> String? {
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assertIsOnSerialQueue()
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guard OWSLinkPreview.featureEnabled else {
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return nil
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}
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guard let body = body else {
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return nil
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}
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if let cachedUrl = previewUrlCache.object(forKey: body as AnyObject) as? String {
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Logger.verbose("URL parsing cache hit.")
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guard cachedUrl.count > 0 else {
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return nil
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}
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return cachedUrl
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}
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let components = body.components(separatedBy: .whitespacesAndNewlines)
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for component in components {
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if isValidLinkUrl(component) {
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previewUrlCache.setObject(component as AnyObject, forKey: body as AnyObject)
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return component
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}
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}
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return nil
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}
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// MARK: - Preview Construction
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// This cache should only be accessed on serialQueue.
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private static var linkPreviewInfoCache: NSCache<AnyObject, OWSLinkPreviewInfo> = NSCache()
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// Completion will always be invoked exactly once.
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//
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// The completion is called with a link preview if one can be built for
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// the message body. It building the preview fails, completion will be
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// called with nil to avoid failing the message send.
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//
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// NOTE: Completion might be invoked on any thread.
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@objc
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public class func tryToBuildPreviewInfo(forMessageBodyText body: String?,
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completion: @escaping (OWSLinkPreviewInfo?) -> Void) {
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guard OWSLinkPreview.featureEnabled else {
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completion(nil)
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return
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}
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guard let body = body else {
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completion(nil)
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return
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}
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serialQueue.async {
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guard let previewUrl = previewUrl(forMessageBodyText: body) else {
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completion(nil)
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return
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}
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if let cachedInfo = linkPreviewInfoCache.object(forKey: previewUrl as AnyObject) {
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Logger.verbose("Link preview info cache hit.")
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completion(cachedInfo)
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return
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}
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downloadContents(ofUrl: previewUrl, completion: { (data) in
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DispatchQueue.global().async {
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guard let data = data else {
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completion(nil)
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return
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}
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parse(linkData: data, linkUrlString: previewUrl) { (linkPreviewInfo) in
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guard let linkPreviewInfo = linkPreviewInfo else {
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completion(nil)
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return
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}
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guard linkPreviewInfo.isValid() else {
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completion(nil)
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return
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}
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serialQueue.async {
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previewUrlCache.setObject(linkPreviewInfo, forKey: previewUrl as AnyObject)
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DispatchQueue.global().async {
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completion(linkPreviewInfo)
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}
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}
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}
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}
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})
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}
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}
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private class func downloadContents(ofUrl url: String,
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completion: @escaping (Data?) -> Void,
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remainingRetries: UInt = 3) {
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Logger.verbose("url: \(url)")
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guard let sessionManager: AFHTTPSessionManager = ReverseProxy.sessionManager(baseUrl: nil) else {
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owsFailDebug("Couldn't create session manager.")
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completion(nil)
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return
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}
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sessionManager.requestSerializer = AFHTTPRequestSerializer()
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sessionManager.responseSerializer = AFHTTPResponseSerializer()
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// Remove all headers from the request.
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for headerField in sessionManager.requestSerializer.httpRequestHeaders.keys {
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sessionManager.requestSerializer.setValue(nil, forHTTPHeaderField: headerField)
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}
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sessionManager.get(url,
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parameters: {},
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progress: nil,
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success: { _, value in
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guard let data = value as? Data else {
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Logger.warn("Result is not data: \(type(of: value)).")
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completion(nil)
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return
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}
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completion(data)
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},
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failure: { _, error in
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Logger.verbose("Error: \(error)")
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guard isRetryable(error: error) else {
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Logger.warn("Error is not retryable.")
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completion(nil)
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return
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}
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guard remainingRetries > 0 else {
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Logger.warn("No more retries.")
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completion(nil)
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return
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}
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OWSLinkPreview.downloadContents(ofUrl: url, completion: completion, remainingRetries: remainingRetries - 1)
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})
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}
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private class func isRetryable(error: Error) -> Bool {
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let nsError = error as NSError
|
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if nsError.domain == kCFErrorDomainCFNetwork as String {
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// Network failures are retried.
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|
return true
|
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}
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return false
|
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}
|
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|
// Example:
|
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|
|
//
|
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|
|
|
// <meta property="og:title" content="Randomness is Random - Numberphile">
|
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|
|
// <meta property="og:image" content="https://i.ytimg.com/vi/tP-Ipsat90c/maxresdefault.jpg">
|
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|
|
|
private class func parse(linkData: Data,
|
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|
|
|
linkUrlString: String,
|
|
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|
|
completion: @escaping (OWSLinkPreviewInfo?) -> Void) {
|
|
|
|
|
guard let linkText = String(bytes: linkData, encoding: .utf8) else {
|
|
|
|
|
owsFailDebug("Could not parse link text.")
|
|
|
|
|
completion(nil)
|
|
|
|
|
return
|
|
|
|
|
}
|
|
|
|
|
Logger.verbose("linkText: \(linkText)")
|
|
|
|
|
|
|
|
|
|
let title = parseFirstMatch(pattern: "<meta property=\"og:title\" content=\"([^\"]+)\">", text: linkText)
|
|
|
|
|
Logger.verbose("title: \(String(describing: title))")
|
|
|
|
|
|
|
|
|
|
guard let imageUrlString = parseFirstMatch(pattern: "<meta property=\"og:image\" content=\"([^\"]+)\">", text: linkText) else {
|
|
|
|
|
return completion(OWSLinkPreviewInfo(urlString: linkUrlString, title: title))
|
|
|
|
|
}
|
|
|
|
|
Logger.verbose("imageUrlString: \(imageUrlString)")
|
|
|
|
|
guard let imageUrl = URL(string: imageUrlString) else {
|
|
|
|
|
Logger.error("Could not parse image URL.")
|
|
|
|
|
return completion(OWSLinkPreviewInfo(urlString: linkUrlString, title: title))
|
|
|
|
|
}
|
|
|
|
|
let imageFilename = imageUrl.lastPathComponent
|
|
|
|
|
let imageFileExtension = (imageFilename as NSString).pathExtension.lowercased()
|
|
|
|
|
guard let imageMimeType = MIMETypeUtil.mimeType(forFileExtension: imageFileExtension) else {
|
|
|
|
|
Logger.error("Image URL has unknown content type: \(imageFileExtension).")
|
|
|
|
|
return completion(OWSLinkPreviewInfo(urlString: linkUrlString, title: title))
|
|
|
|
|
}
|
|
|
|
|
let kValidMimeTypes = [
|
|
|
|
|
OWSMimeTypeImagePng,
|
|
|
|
|
OWSMimeTypeImageJpeg
|
|
|
|
|
]
|
|
|
|
|
guard kValidMimeTypes.contains(imageMimeType) else {
|
|
|
|
|
Logger.error("Image URL has invalid content type: \(imageMimeType).")
|
|
|
|
|
return completion(OWSLinkPreviewInfo(urlString: linkUrlString, title: title))
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
downloadContents(ofUrl: imageUrlString,
|
|
|
|
|
completion: { (imageData) in
|
|
|
|
|
guard let imageData = imageData else {
|
|
|
|
|
Logger.error("Could not download image.")
|
|
|
|
|
return completion(OWSLinkPreviewInfo(urlString: linkUrlString, title: title))
|
|
|
|
|
}
|
|
|
|
|
let imageFilePath = OWSFileSystem.temporaryFilePath(withFileExtension: imageFileExtension)
|
|
|
|
|
do {
|
|
|
|
|
try imageData.write(to: NSURL.fileURL(withPath: imageFilePath), options: .atomicWrite)
|
|
|
|
|
} catch let error as NSError {
|
|
|
|
|
owsFailDebug("file write failed: \(imageFilePath), \(error)")
|
|
|
|
|
return completion(OWSLinkPreviewInfo(urlString: linkUrlString, title: title))
|
|
|
|
|
}
|
|
|
|
|
// NOTE: imageSize(forFilePath:...) will call ows_isValidImage(...).
|
|
|
|
|
let imageSize = NSData.imageSize(forFilePath: imageFilePath, mimeType: imageMimeType)
|
|
|
|
|
let kMaxImageSize: CGFloat = 2048
|
|
|
|
|
guard imageSize.width > 0,
|
|
|
|
|
imageSize.height > 0,
|
|
|
|
|
imageSize.width < kMaxImageSize,
|
|
|
|
|
imageSize.height < kMaxImageSize else {
|
|
|
|
|
Logger.error("Image has invalid size: \(imageSize).")
|
|
|
|
|
return completion(OWSLinkPreviewInfo(urlString: linkUrlString, title: title))
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
let linkPreviewInfo = OWSLinkPreviewInfo(urlString: linkUrlString, title: title, imageFilePath: imageFilePath)
|
|
|
|
|
completion(linkPreviewInfo)
|
|
|
|
|
})
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
private class func parseFirstMatch(pattern: String,
|
|
|
|
|
text: String) -> String? {
|
|
|
|
|
do {
|
|
|
|
|
let regex = try NSRegularExpression(pattern: pattern)
|
|
|
|
|
guard let match = regex.firstMatch(in: text,
|
|
|
|
|
options: [],
|
|
|
|
|
range: NSRange(location: 0, length: text.count)) else {
|
|
|
|
|
return nil
|
|
|
|
|
}
|
|
|
|
|
let matchRange = match.range(at: 1)
|
|
|
|
|
guard let textRange = Range(matchRange, in: text) else {
|
|
|
|
|
owsFailDebug("Invalid match.")
|
|
|
|
|
return nil
|
|
|
|
|
}
|
|
|
|
|
let substring = String(text[textRange])
|
|
|
|
|
return substring
|
|
|
|
|
} catch {
|
|
|
|
|
Logger.error("Error: \(error)")
|
|
|
|
|
return nil
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
Matthew Chen
6 years ago