linux support

.github/workflows/swift.yml

@@ -8,7 +8,11 @@ on:
 
 jobs:
   build:
-    runs-on: macos-12
+    name: Lint & Build swift on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-12]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/cache@v2

Package.swift

@@ -3,7 +3,18 @@
 
 import PackageDescription
 
+// Currently, CommonCrypto and CryptoKit are not available under Linux.
+// If CommonCrypto is not available, swift-crypto should be used.
+
+#if canImport(CommonCrypto)
+let dependencies: [Package.Dependency] = []
+let tDependencies: [Target.Dependency] = []
+#else // for Linux
+let dependencies: [Package.Dependency] = [.package(url: "https://github.com/apple/swift-crypto.git", from: "3.8.0")]
+let tDependencies: [Target.Dependency] = [.product(name: "Crypto", package: "swift-crypto")]
+#endif
+
 let package = Package(
     name: "TwitterAPIKit",
     platforms: [
         .macOS(.v10_14),
@@ -17,13 +28,13 @@
             name: "TwitterAPIKit",
             targets: ["TwitterAPIKit"]),
     ],
-    dependencies: [],
+    dependencies: dependencies,
     targets: [
         // Targets are the basic building blocks of a package. A target can define a module or a test suite.
         // Targets can depend on other targets in this package, and on products in packages this package depends on.
         .target(
             name: "TwitterAPIKit",
-            dependencies: []),
+            dependencies: tDependencies),
         .testTarget(
             name: "TwitterAPIKitTests",
             dependencies: ["TwitterAPIKit"]),

Sources/TwitterAPIKit/Extensions/Data.swift

@@ -1,31 +1,6 @@
-import CommonCrypto
 import Foundation
 
 extension Data {
-    func hmac(key: Data) -> Data {
-
-        // Thanks: https://github.com/jernejstrasner/SwiftCrypto
-
-        let digestLen = Int(CC_SHA1_DIGEST_LENGTH)
-        return withUnsafeBytes { bytes -> Data in
-            let result = UnsafeMutablePointer<UInt8>.allocate(capacity: digestLen)
-            defer {
-                result.deallocate()
-            }
-
-            key.withUnsafeBytes { body in
-                CCHmac(
-                    CCHmacAlgorithm(kCCHmacAlgSHA1),
-                    body.baseAddress,
-                    key.count, bytes.baseAddress,
-                    count,
-                    result
-                )
-            }
-
-            return Data(bytes: result, count: digestLen)
-        }
-    }
 
     func split(separator: Data, omittingEmptySubsequences: Bool = true) -> [Data] {
         var current = startIndex

Sources/TwitterAPIKit/Extensions/HMAC.swift

@@ -0,0 +1,44 @@
+import Foundation
+
+#if canImport(CommonCrypto)
+    import CommonCrypto
+
+    extension Data {
+        fileprivate func hmac(key: Data) -> Data {
+
+            // Thanks: https://github.com/jernejstrasner/SwiftCrypto
+
+            let digestLen = Int(CC_SHA1_DIGEST_LENGTH)
+            return withUnsafeBytes { bytes -> Data in
+                let result = UnsafeMutablePointer<UInt8>.allocate(capacity: digestLen)
+                defer {
+                    result.deallocate()
+                }
+
+                key.withUnsafeBytes { body in
+                    CCHmac(
+                        CCHmacAlgorithm(kCCHmacAlgSHA1),
+                        body.baseAddress,
+                        key.count, bytes.baseAddress,
+                        count,
+                        result
+                    )
+                }
+
+                return Data(bytes: result, count: digestLen)
+            }
+        }
+    }
+
+    func createHMACSHA1(key: Data, message: Data) -> Data {
+        return message.hmac(key: key)
+    }
+
+#elseif canImport(Crypto)  // for Linux
+    import Crypto
+    func createHMACSHA1(key: Data, message: Data) -> Data {
+        return Data(HMAC<Insecure.SHA1>.authenticationCode(for: message, using: SymmetricKey(data: key)))
+    }
+#else
+    #error("Crypto is not available in this environment.")
+#endif

Sources/TwitterAPIKit/OAuthHelper.swift

@@ -1,4 +1,3 @@
-import CommonCrypto
 import Foundation
 
 private let oauthVersion = "1.0"
@@ -69,6 +68,6 @@ private func oauthSignature(
 
     let key = signingKey.data(using: .utf8)!
     let msg = signatureBaseString.data(using: .utf8)!
-    let sha1 = msg.hmac(key: key)
+    let sha1 = createHMACSHA1(key: key, message: msg)
     return sha1.base64EncodedString(options: [])
 }

Sources/TwitterAPIKit/TwitterAPIKit.swift

@@ -1,5 +1,9 @@
 import Foundation
 
+#if canImport(FoundationNetworking)
+    @_exported import FoundationNetworking
+#endif
+
 public enum TwitterBaseURLType {
     case twitter
     case api

Sources/TwitterAPIKit/TwitterAPIResponse.swift

@@ -143,8 +143,12 @@ extension String {
     }
 
     fileprivate var unescapingUnicodeCharacters: String {
-        let mutableString = NSMutableString(string: self)
-        CFStringTransform(mutableString, nil, "Any-Hex/Java" as NSString, true)
-        return mutableString as String
+        #if os(Linux)
+            return self
+        #else
+            let mutableString = NSMutableString(string: self)
+            CFStringTransform(mutableString, nil, "Any-Hex/Java" as NSString, true)
+            return mutableString as String
+        #endif
     }
 }