Config file: Parsing a wg-quick config file

Signed-off-by: Roopesh Chander <roop@roopc.net>

WireGuard/WireGuard.xcodeproj/project.pbxproj

@@ -12,6 +12,7 @@
 		6F628C41217F47DB003482A3 /* TunnelDetailTableViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F628C40217F47DB003482A3 /* TunnelDetailTableViewController.swift */; };
 		6F6899A62180447E0012E523 /* x25519.c in Sources */ = {isa = PBXBuildFile; fileRef = 6F6899A52180447E0012E523 /* x25519.c */; };
 		6F6899A8218044FC0012E523 /* Curve25519.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F6899A7218044FC0012E523 /* Curve25519.swift */; };
+		6F6899AC218099F00012E523 /* WgQuickConfigFileParser.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F6899AB218099F00012E523 /* WgQuickConfigFileParser.swift */; };
 		6F693A562179E556008551C1 /* Endpoint.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F693A552179E556008551C1 /* Endpoint.swift */; };
 		6F7774E1217181B1006A79B3 /* MainViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F7774DF217181B1006A79B3 /* MainViewController.swift */; };
 		6F7774E2217181B1006A79B3 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F7774E0217181B1006A79B3 /* AppDelegate.swift */; };
@@ -33,6 +34,7 @@
 		6F6899A42180447E0012E523 /* x25519.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = x25519.h; sourceTree = "<group>"; };
 		6F6899A52180447E0012E523 /* x25519.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = x25519.c; sourceTree = "<group>"; };
 		6F6899A7218044FC0012E523 /* Curve25519.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Curve25519.swift; sourceTree = "<group>"; };
+		6F6899AB218099F00012E523 /* WgQuickConfigFileParser.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WgQuickConfigFileParser.swift; sourceTree = "<group>"; };
 		6F693A552179E556008551C1 /* Endpoint.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Endpoint.swift; sourceTree = "<group>"; };
 		6F7774DF217181B1006A79B3 /* MainViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MainViewController.swift; sourceTree = "<group>"; };
 		6F7774E0217181B1006A79B3 /* AppDelegate.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
@@ -72,6 +74,14 @@
 			path = Crypto;
 			sourceTree = "<group>";
 		};
+		6F6899AA218099D00012E523 /* Parsing */ = {
+			isa = PBXGroup;
+			children = (
+				6F6899AB218099F00012E523 /* WgQuickConfigFileParser.swift */,
+			);
+			path = Parsing;
+			sourceTree = "<group>";
+		};
 		6F7774DD217181B1006A79B3 /* UI */ = {
 			isa = PBXGroup;
 			children = (
@@ -133,6 +143,7 @@
 			isa = PBXGroup;
 			children = (
 				6F6899A32180445A0012E523 /* Crypto */,
+				6F6899AA218099D00012E523 /* Parsing */,
 				6F7774E6217201E0006A79B3 /* Model */,
 				6F7774DD217181B1006A79B3 /* UI */,
 				6F7774ED21722D0C006A79B3 /* VPN */,
@@ -230,6 +241,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				6F6899AC218099F00012E523 /* WgQuickConfigFileParser.swift in Sources */,
 				6F7774E421718281006A79B3 /* TunnelsListTableViewController.swift in Sources */,
 				6F7774EF21722D97006A79B3 /* TunnelsManager.swift in Sources */,
 				6F693A562179E556008551C1 /* Endpoint.swift in Sources */,

WireGuard/WireGuard/Parsing/WgQuickConfigFileParser.swift

@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: MIT
+// Copyright © 2018 WireGuard LLC. All rights reserved.
+
+import Foundation
+
+class WgQuickConfigFileParser {
+
+    enum ParserState {
+        case inInterfaceSection
+        case inPeerSection
+        case notInASection
+    }
+
+    enum ParseError: Error {
+        case invalidLine(_ line: String.SubSequence)
+        case noInterface
+        case invalidInterface
+        case multipleInterfaces
+        case invalidPeer
+    }
+
+    // Based on the parser written by Eric Kuck <eric@bluelinelabs.com> in commit 5ef1656
+
+    static func parse(_ text: String, name: String) throws -> TunnelConfiguration {
+
+        assert(!name.isEmpty)
+
+        func collate(interfaceAttributes attributes: [String:String]) -> InterfaceConfiguration? {
+            // required wg fields
+            guard let privateKeyString = attributes["PrivateKey"] else { return nil }
+            guard let privateKey = Data(base64Encoded: privateKeyString), privateKey.count == 32 else { return nil }
+            var interface = InterfaceConfiguration(name: name, privateKey: privateKey)
+            // other wg fields
+            if let listenPortString = attributes["ListenPort"] {
+                guard let listenPort = UInt16(listenPortString) else { return nil }
+                interface.listenPort = listenPort
+            }
+            // wg-quick fields
+            if let addressesString = attributes["Address"] {
+                var addresses: [IPAddressRange] = []
+                for addressString in addressesString.split(separator: ",") {
+                    let trimmedString = addressString.trimmingCharacters(in: .whitespaces)
+                    guard let address = IPAddressRange(from: trimmedString) else { return nil }
+                    addresses.append(address)
+                }
+                interface.addresses = addresses
+            }
+            if let dnsString = attributes["DNS"] {
+                var dnsServers: [DNSServer] = []
+                for dnsServerString in dnsString.split(separator: ",") {
+                    let trimmedString = dnsServerString.trimmingCharacters(in: .whitespaces)
+                    guard let dnsServer = DNSServer(from: trimmedString) else { return nil }
+                    dnsServers.append(dnsServer)
+                }
+                interface.dns = dnsServers
+            }
+            if let mtuString = attributes["MTU"] {
+                guard let mtu = UInt16(mtuString) else { return nil }
+                interface.mtu = mtu
+            }
+            return interface
+        }
+
+        func collate(peerAttributes attributes: [String:String]) -> PeerConfiguration? {
+            // required wg fields
+            guard let publicKeyString = attributes["PublicKey"] else { return nil }
+            guard let publicKey = Data(base64Encoded: publicKeyString), publicKey.count == 32 else { return nil }
+            var peer = PeerConfiguration(publicKey: publicKey)
+            // wg fields
+            if let preSharedKeyString = attributes["PreSharedKey"] {
+                guard let preSharedKey = Data(base64Encoded: preSharedKeyString), preSharedKey.count == 32 else { return nil }
+                peer.preSharedKey = preSharedKey
+            }
+            if let allowedIPsString = attributes["AllowedIPs"] {
+                var allowedIPs: [IPAddressRange] = []
+                for allowedIPString in allowedIPsString.split(separator: ",") {
+                    let trimmedString = allowedIPString.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines)
+                    guard let allowedIP = IPAddressRange(from: trimmedString) else { return nil }
+                    allowedIPs.append(allowedIP)
+                }
+                peer.allowedIPs = allowedIPs
+            }
+            if let endpointString = attributes["Endpoint"] {
+                guard let endpoint = Endpoint(from: endpointString) else { return nil }
+                peer.endpoint = endpoint
+            }
+            if let persistentKeepAliveString = attributes["PersistentKeepalive"] {
+                guard let persistentKeepAlive = UInt16(persistentKeepAliveString) else { return nil }
+                peer.persistentKeepAlive = persistentKeepAlive
+            }
+            return peer
+        }
+
+        var interfaceConfiguration: InterfaceConfiguration? = nil
+        var peerConfigurations: [PeerConfiguration] = []
+
+        let lines = text.split(separator: "\n")
+
+        var parserState: ParserState = .notInASection
+        var attributes: [String:String] = [:]
+
+        for (lineIndex, line) in lines.enumerated() {
+            var trimmedLine: String
+            if let commentRange = line.range(of: "#") {
+                trimmedLine = String(line[..<commentRange.lowerBound])
+            } else {
+                trimmedLine = String(line)
+            }
+
+            trimmedLine = trimmedLine.trimmingCharacters(in: .whitespaces)
+
+            guard trimmedLine.count > 0 else { continue }
+            let lowercasedLine = line.lowercased()
+
+            if let equalsIndex = line.firstIndex(of: "=") {
+                // Line contains an attribute
+                let key = line[..<equalsIndex].trimmingCharacters(in: .whitespaces)
+                let value = line[line.index(equalsIndex, offsetBy: 1)...].trimmingCharacters(in: .whitespaces)
+                attributes[key] = value
+            } else {
+                if (lowercasedLine != "[interface]" && lowercasedLine != "[peer]") {
+                    throw ParseError.invalidLine(line)
+                }
+            }
+
+            let isLastLine: Bool = (lineIndex == lines.count - 1)
+
+            if (isLastLine || lowercasedLine == "[interface]" || lowercasedLine == "[peer]") {
+                // Previous section has ended; process the attributes collected so far
+                if (parserState == .inInterfaceSection) {
+                    guard let interface = collate(interfaceAttributes: attributes) else { throw ParseError.invalidInterface }
+                    guard (interfaceConfiguration == nil) else { throw ParseError.multipleInterfaces }
+                    interfaceConfiguration = interface
+                } else if (parserState == .inPeerSection) {
+                    guard let peer = collate(peerAttributes: attributes) else { throw ParseError.invalidPeer }
+                    peerConfigurations.append(peer)
+                }
+            }
+
+            if (lowercasedLine == "[interface]") {
+                parserState = .inInterfaceSection
+                attributes.removeAll()
+            } else if (lowercasedLine == "[peer]") {
+                parserState = .inPeerSection
+                attributes.removeAll()
+            }
+        }
+
+        if let interfaceConfiguration = interfaceConfiguration {
+            let tunnelConfiguration = TunnelConfiguration(interface: interfaceConfiguration)
+            tunnelConfiguration.peers = peerConfigurations
+            return tunnelConfiguration
+        } else {
+            throw ParseError.noInterface
+        }
+    }
+}