convert setPktInfo() to SocketOption

FlyingSocks/Sources/Socket.swift

@@ -94,9 +94,6 @@ public struct Socket: Sendable, Hashable {
             throw SocketError.makeFailed("CreateSocket")
         }
         self.file = descriptor
-        if type == .datagram {
-            try setPktInfo(domain: domain)
-        }
     }
 
     public var socketType: SocketType {
@@ -121,29 +118,6 @@ public struct Socket: Sendable, Hashable {
         }
     }
 
-    // enable return of ip_pktinfo/ipv6_pktinfo on recvmsg()
-    private func setPktInfo(domain: Int32) throws {
-        var enable = Int32(1)
-        let level: Int32
-        let name: Int32
-
-        switch domain {
-        case AF_INET:
-            level = Socket.ipproto_ip
-            name = Self.ip_pktinfo
-        case AF_INET6:
-            level = Socket.ipproto_ipv6
-            name = Self.ipv6_pktinfo
-        default:
-            return
-        }
-
-        let result = Socket.setsockopt(file.rawValue, level, name, &enable, socklen_t(MemoryLayout<Int32>.size))
-        guard result >= 0 else {
-            throw SocketError.makeFailed("SetPktInfoOption")
-        }
-    }
-
     public func setValue<O: SocketOption>(_ value: O.Value, for option: O) throws {
         var value = option.makeSocketValue(from: value)
         let result = withUnsafeBytes(of: &value) {
@@ -573,6 +547,14 @@ public extension SocketOption where Self == BoolSocketOption {
         BoolSocketOption(name: SO_REUSEADDR)
     }
 
+    static var packetInfoIP: Self {
+        BoolSocketOption(level: Socket.ipproto_ip, name: Socket.ip_pktinfo)
+    }
+
+    static var packetInfoIPv6: Self {
+        BoolSocketOption(level: Socket.ipproto_ipv6, name: Socket.ipv6_pktinfo)
+    }
+
     #if canImport(Darwin)
     // Prevents SIG_TRAP when app is paused / running in background.
     static var noSIGPIPE: Self {

FlyingSocks/Tests/SocketTests.swift

@@ -321,6 +321,45 @@ struct SocketTests {
             try Socket.inet_ntop(AF_INET6, &addr.sin6_addr, buffer, maxLength)
         }
     }
+
+    @Test
+    func makes_datagram_ip4() throws {
+        #expect(throws: Never.self) {
+            try Socket(domain: Int32(sa_family_t(AF_INET)), type: .datagram)
+        }
+    }
+
+    @Test
+    func makes_datagram_ip6() throws {
+        #expect(throws: Never.self) {
+            try Socket(domain: Int32(sa_family_t(AF_INET6)), type: .datagram)
+        }
+    }
+
+    @Test
+    func packetInfoIP() throws {
+        let socket = try Socket(domain: Int32(sa_family_t(AF_INET)), type: .datagram)
+        #expect(
+            try socket.getValue(for: .packetInfoIP) == false
+        )
+
+        try socket.setValue(true, for: .packetInfoIP)
+        #expect(
+            try socket.getValue(for: .packetInfoIP) == true
+        )
+    }
+
+    @Test
+    func packetInfoIPv6() throws {
+        let socket = try Socket(domain: Int32(sa_family_t(AF_INET6)), type: .datagram)
+
+        withKnownIssue("Permission denied error is thrown") {
+            try socket.setValue(true, for: .packetInfoIPv6)
+            #expect(
+                try socket.getValue(for: .packetInfoIPv6) == true
+            )
+        }
+    }
 }
 
 extension Socket.Flags {

FlyingSocks/XCTests/SocketTests.swift

@@ -258,6 +258,60 @@ final class SocketTests: XCTestCase {
         let buffer = UnsafeMutablePointer<CChar>.allocate(capacity: Int(maxLength))
         XCTAssertThrowsError(try Socket.inet_ntop(AF_INET6, &addr.sin6_addr, buffer, maxLength))
     }
+
+    func testMakes_datagram_ip4() throws {
+        XCTAssertNoThrow(
+            try Socket(domain: Int32(sa_family_t(AF_INET)), type: .datagram)
+        )
+    }
+
+    func testMakes_datagram_ip6() throws {
+        XCTAssertNoThrow(
+            try Socket(domain: Int32(sa_family_t(AF_INET6)), type: .datagram)
+        )
+    }
+
+    func testPacketInfoIP() throws {
+        let socket = try Socket(domain: Int32(sa_family_t(AF_INET)), type: .datagram)
+        XCTAssertFalse(
+            try socket.getValue(for: .packetInfoIP)
+        )
+
+        try socket.setValue(true, for: .packetInfoIP)
+        XCTAssertTrue(
+            try socket.getValue(for: .packetInfoIP)
+        )
+    }
+
+    #if canImport(Darwin)
+    func testPacketInfoIPv6() throws {
+        let socket = try Socket(domain: Int32(sa_family_t(AF_INET6)), type: .datagram)
+        XCTAssertFalse(
+            try socket.getValue(for: .packetInfoIPv6)
+        )
+
+        try XCTExpectFailure("Permission denied error is thrown") {
+            try socket.setValue(true, for: .packetInfoIPv6)
+            XCTAssertTrue(
+                try socket.getValue(for: .packetInfoIPv6)
+            )
+        }
+    }
+    #else
+    // Linux does not support XCTExpectFailure
+    func testPacketInfoIPv6() throws {
+        let socket = try Socket(domain: Int32(sa_family_t(AF_INET6)), type: .datagram)
+        do {
+            try socket.setValue(true, for: .packetInfoIPv6)
+            XCTAssertTrue(
+                try socket.getValue(for: .packetInfoIPv6)
+            )
+            XCTFail("Expected Failure")
+        } catch {
+            () // expected failure
+        }
+    }
+    #endif
 }
 
 extension Socket.Flags {