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UserAgentManager.swift
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/
UserAgentManager.swift
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//
// UserAgentManager.swift
// Core
//
// Copyright © 2020 DuckDuckGo. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
import Foundation
import WebKit
import BrowserServicesKit
public protocol UserAgentManager {
func update(request: inout URLRequest, isDesktop: Bool)
func update(webView: WKWebView, isDesktop: Bool, url: URL?)
func userAgent(isDesktop: Bool) -> String
}
public class DefaultUserAgentManager: UserAgentManager {
public static let shared: UserAgentManager = DefaultUserAgentManager()
private var userAgent = UserAgent()
init() {
prepareUserAgent()
}
private func prepareUserAgent() {
let webview = WKWebView()
webview.load(URLRequest.developerInitiated(URL(string: "about:blank")!))
getDefaultAgent(webView: webview) { [weak self] agent in
// Reference webview instance to keep it in scope and allow UA to be returned
_ = webview
guard let defaultAgent = agent else { return }
self?.userAgent = UserAgent(defaultAgent: defaultAgent)
}
}
public func userAgent(isDesktop: Bool) -> String {
return userAgent.agent(forUrl: nil, isDesktop: isDesktop)
}
public func update(request: inout URLRequest, isDesktop: Bool) {
request.addValue(userAgent.agent(forUrl: nil, isDesktop: isDesktop), forHTTPHeaderField: "User-Agent")
}
public func update(webView: WKWebView, isDesktop: Bool, url: URL?) {
let agent = userAgent.agent(forUrl: url, isDesktop: isDesktop)
webView.customUserAgent = agent
}
private func getDefaultAgent(webView: WKWebView, completion: @escaping (String?) -> Void) {
webView.evaluateJavaScript("navigator.userAgent") { (result, _) in
let agent = result as? String
completion(agent)
}
}
}
struct UserAgent {
private struct Constants {
// swiftlint:disable line_length
static let fallbackWekKitVersion = "605.1.15"
static let fallbackSafariComponent = "Safari/\(fallbackWekKitVersion)"
static let fallbackDefaultAgent = "Mozilla/5.0 (iPhone; CPU iPhone OS 13_5 like Mac OS X) AppleWebKit/\(fallbackWekKitVersion) (KHTML, like Gecko) Mobile/15E148"
static let desktopPrefixComponent = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15)"
static let fallbackVersionComponent = "Version/13.1.1"
static let uaOmitSitesConfigKey = "omitApplicationSites"
static let uaOmitDomainConfigKey = "domain"
// swiftlint:enable line_length
}
private struct Regex {
static let suffix = "(AppleWebKit/.*) Mobile"
static let webKitVersion = "AppleWebKit/([^ ]+) "
static let osVersion = " OS ([0-9_]+)"
}
private let baseAgent: String
private let baseDesktopAgent: String
private let versionComponent: String
private let safariComponent: String
private let applicationComponent = "DuckDuckGo/\(AppVersion.shared.majorVersionNumber)"
init(defaultAgent: String = Constants.fallbackDefaultAgent) {
versionComponent = UserAgent.createVersionComponent(fromAgent: defaultAgent)
baseAgent = UserAgent.createBaseAgent(fromAgent: defaultAgent, versionComponent: versionComponent)
baseDesktopAgent = UserAgent.createBaseDesktopAgent(fromAgent: defaultAgent, versionComponent: versionComponent)
safariComponent = UserAgent.createSafariComponent(fromAgent: baseAgent)
}
private func omitApplicationSites(forConfig config: PrivacyConfiguration) -> [String] {
let uaSettings = config.settings(for: .customUserAgent)
let omitApplicationObjs = uaSettings[Constants.uaOmitSitesConfigKey] as? [[String: String]] ?? []
return omitApplicationObjs.map { $0[Constants.uaOmitDomainConfigKey] ?? "" }
}
public func agent(forUrl url: URL?, isDesktop: Bool,
privacyConfig: PrivacyConfiguration = ContentBlocking.privacyConfigurationManager.privacyConfig) -> String {
let omittedSites = omitApplicationSites(forConfig: privacyConfig)
let customUAEnabled = privacyConfig.isEnabled(featureKey: .customUserAgent)
let omitApplicationComponent = !customUAEnabled || omittedSites.contains { domain in
url?.isPart(ofDomain: domain) ?? false
}
let resolvedApplicationComponent = !omitApplicationComponent ? applicationComponent : nil
if isDesktop {
return concatWithSpaces(baseDesktopAgent, resolvedApplicationComponent, safariComponent)
} else {
return concatWithSpaces(baseAgent, resolvedApplicationComponent, safariComponent)
}
}
private func concatWithSpaces(_ elements: String?...) -> String {
return elements
.compactMap { $0 }
.joined(separator: " ")
}
private static func createVersionComponent(fromAgent agent: String) -> String {
let regex = try? NSRegularExpression(pattern: Regex.osVersion)
let match = regex?.firstMatch(in: agent, options: [], range: NSRange(location: 0, length: agent.count))
guard let range = match?.range(at: 1) else {
return Constants.fallbackVersionComponent
}
let version = (agent as NSString).substring(with: range)
let versionComponents = version.split(separator: "_").prefix(2)
guard versionComponents.count > 1 else {
return Constants.fallbackVersionComponent
}
return "Version/\(versionComponents.joined(separator: "."))"
}
private static func createSafariComponent(fromAgent agent: String) -> String {
let regex = try? NSRegularExpression(pattern: Regex.webKitVersion)
let match = regex?.firstMatch(in: agent, options: [], range: NSRange(location: 0, length: agent.count))
guard let range = match?.range(at: 1) else {
return Constants.fallbackSafariComponent
}
let version = (agent as NSString).substring(with: range)
return "Safari/\(version)"
}
private static func createBaseAgent(fromAgent agent: String,
versionComponent: String) -> String {
var agentComponents = agent.split(separator: " ")
guard !agentComponents.isEmpty else {
return agent
}
agentComponents.insert(.init(versionComponent), at: agentComponents.endIndex - 1)
return agentComponents.joined(separator: " ")
}
private static func createBaseDesktopAgent(fromAgent agent: String,
versionComponent: String) -> String {
let regex = try? NSRegularExpression(pattern: Regex.suffix)
let match = regex?.firstMatch(in: agent, options: [], range: NSRange(location: 0, length: agent.count))
guard let range = match?.range(at: 1) else {
return createBaseDesktopAgent(fromAgent: Constants.fallbackDefaultAgent,
versionComponent: versionComponent)
}
let suffix = (agent as NSString).substring(with: range)
return "\(Constants.desktopPrefixComponent) \(suffix) \(versionComponent)"
}
}