Added Socket.address()

Author: colemancda

Sources/Socket/System/SocketOperations.swift

@@ -616,4 +616,27 @@ extension SocketDescriptor {
         system_write(self.rawValue, buffer.baseAddress, buffer.count)
       }
     }
+    
+    @_alwaysEmitIntoClient
+    public func address<Address: SocketAddress>(
+        _ address: Address.Type,
+        retryOnInterrupt: Bool = true
+    ) throws -> Address {
+        return try _getAddress(address, retryOnInterrupt: retryOnInterrupt).get()
+    }
+    
+    @usableFromInline
+    internal func _getAddress<Address: SocketAddress>(
+        _ address: Address.Type,
+        retryOnInterrupt: Bool
+    ) -> Result<Address, Errno> {
+        var result: Result<CInt, Errno> = .success(0)
+        let address = Address.withUnsafePointer { socketPointer, socketLength in
+            var length = socketLength
+            result = valueOrErrno(retryOnInterrupt: retryOnInterrupt) {
+                system_getsockname(self.rawValue, socketPointer, &length)
+            }
+        }
+        return result.map { _ in address }
+    }
 }

Sources/Socket/System/Syscalls.swift

@@ -467,3 +467,10 @@ internal func system_link_ntoa(_ address: UnsafePointer<sockaddr_dl>) -> UnsafeM
     return link_ntoa(address)
 }
 #endif
+
+internal func system_getsockname(_ fd: CInt, _ address: UnsafeMutablePointer<CInterop.SocketAddress>, _ length: UnsafeMutablePointer<UInt32>) -> CInt {
+#if ENABLE_MOCKING
+    if mockingEnabled { return _mock(fd, address) }
+#endif
+    return getsockname(fd, address, length)
+}

Tests/SocketTests/SocketTests.swift

@@ -48,6 +48,7 @@ final class SocketTests: XCTestCase {
                 IPv4Protocol.tcp,
                 bind: address
             )
+            XCTAssertEqual(try server.fileDescriptor.address(IPv4SocketAddress.self), address)
             defer { Task { await server.close() } }
             NSLog("Server: Created server socket \(server.fileDescriptor)")
             try server.fileDescriptor.listen(backlog: 10)
@@ -58,6 +59,7 @@ final class SocketTests: XCTestCase {
                     fileDescriptor: try await server.fileDescriptor.accept()
                 )
                 NSLog("Server: Got incoming connection \(newConnection.fileDescriptor)")
+                XCTAssertEqual(try newConnection.fileDescriptor.address(IPv4SocketAddress.self).address.rawValue, "127.0.0.1")
                 let _ = try await newConnection.write(data)
                 NSLog("Server: Wrote outgoing data")
             } catch {
@@ -69,13 +71,15 @@ final class SocketTests: XCTestCase {
         let client = try await Socket(
             IPv4Protocol.tcp
         )
+        XCTAssertEqual(try client.fileDescriptor.address(IPv4SocketAddress.self).address, .any)
         defer { Task { await client.close() } }
         NSLog("Client: Created client socket \(client.fileDescriptor)")
 
         NSLog("Client: Will connect to server")
         do { try await client.fileDescriptor.connect(to: address, sleep: 100_000_000) }
         catch Errno.socketIsConnected { }
         NSLog("Client: Connected to server")
+        XCTAssertEqual(try client.fileDescriptor.address(IPv4SocketAddress.self).address.rawValue, "127.0.0.1")
         let read = try await client.read(data.count)
         NSLog("Client: Read incoming data")
         XCTAssertEqual(data, read)