PR: clean up RawSockaddr validation

Signed-off-by: Hamza El-Saawy <hamzaelsaawy@microsoft.com>

file.go

@@ -223,6 +223,7 @@ func (f *win32File) asyncIo(c *ioOperation, d *deadlineHandler, bytes uint32, er
 	// runtime.KeepAlive is needed, as c is passed via native
 	// code to ioCompletionProcessor, c must remain alive
 	// until the channel read is complete.
+	// todo: (de)allocate *ioOperation via win32 heap functions, instead of needing to KeepAlive?
 	runtime.KeepAlive(c)
 	return int(r.bytes), err
 }

hvsock.go

@@ -140,7 +140,10 @@ func (addr *HvsockAddr) fromRaw(raw *rawHvsockAddr) {
 	addr.ServiceID = raw.ServiceID
 }
 
-// Sockaddr interface allows use with `sockets.Bind()` and `.ConnectEx()`
+// Sockaddr returns a pointer to and the size of this struct.
+//
+// Implements the [socket.RawSockaddr] interface, and allows use in
+// [socket.Bind()] and [socket.ConnectEx()]
 func (r *rawHvsockAddr) Sockaddr() (ptr unsafe.Pointer, len int32, err error) {
 	return unsafe.Pointer(r), int32(unsafe.Sizeof(rawHvsockAddr{})), nil
 }

internal/socket/rawaddr.go

@@ -1,41 +1,20 @@
 package socket
 
 import (
-	"errors"
-	"fmt"
 	"unsafe"
 )
 
-// todo: should these be custom types to store the desired/actual size and addr family?
-
-var (
-	ErrBufferSize     = errors.New("buffer size")
-	ErrInvalidPointer = errors.New("invalid pointer")
-	ErrAddrFamily     = errors.New("address family")
-)
-
-// todo: helsaawy - replace this with generics, along with GetSockName and co.
-
-// RawSockaddr allows structs to be used with Bind and ConnectEx. The
+// RawSockaddr allows structs to be used with [Bind] and [ConnectEx]. The
 // struct must meet the Win32 sockaddr requirements specified here:
 // https://docs.microsoft.com/en-us/windows/win32/winsock/sockaddr-2
+//
+// Specifically, the struct size must be least larger than an int16 (unsigned short)
+// for the address family.
 type RawSockaddr interface {
-	// Sockaddr returns a pointer to the RawSockaddr and the length of the struct.
+	// Sockaddr returns a pointer to the RawSockaddr and its struct size, allowing
+	// for the RawSockaddr's data to be overwritten by syscalls (if necessary).
+	//
+	// It is the callers responsibility to validate that the values are valid; invalid
+	// pointers or size can cause a panic.
 	Sockaddr() (unsafe.Pointer, int32, error)
-
-	// FromBytes populates the RawsockAddr with the data in the byte array.
-	// Implementers should check the buffer is correctly sized and the address family
-	// is appropriate.
-	// Receivers should be pointers.
-	FromBytes([]byte) error
-}
-
-func validateSockAddr(ptr unsafe.Pointer, n int32) error {
-	if ptr == nil {
-		return fmt.Errorf("pointer is %p: %w", ptr, ErrInvalidPointer)
-	}
-	if n < 1 {
-		return fmt.Errorf("buffer size %d < 1: %w", n, ErrBufferSize)
-	}
-	return nil
 }

internal/socket/socket.go

@@ -3,6 +3,7 @@
 package socket
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"sync"
@@ -21,57 +22,46 @@ import (
 
 const socketError = uintptr(^uint32(0))
 
-var ErrSocketClosed = fmt.Errorf("socket closed: %w", net.ErrClosed)
+var (
+	// todo(helsaawy): create custom error types to store the desired vs actual size and addr family?
+
+	ErrBufferSize     = errors.New("buffer size")
+	ErrAddrFamily     = errors.New("address family")
+	ErrInvalidPointer = errors.New("invalid pointer")
+	ErrSocketClosed   = fmt.Errorf("socket closed: %w", net.ErrClosed)
+)
+
+// todo(helsaawy): replace these with generics, ie: GetSockName[S RawSockaddr](s windows.Handle) (S, error)
 
-// GetSockName returns the socket's local address. It will call the `rsa.FromBytes()` on the
-// buffer returned by the getsockname syscall. The buffer is allocated to the size specified
-// by `rsa.Sockaddr()`.
+// GetSockName writes the local address of socket s to the [RawSockaddr] rsa.
+// If rsa is not large enough, the [windows.WSAEFAULT] is returned.
 func GetSockName(s windows.Handle, rsa RawSockaddr) error {
 	ptr, l, err := rsa.Sockaddr()
 	if err != nil {
-		return fmt.Errorf("could not find socket size to allocate buffer: %w", err)
-	}
-	if err = validateSockAddr(ptr, l); err != nil {
-		return err
+		return fmt.Errorf("could not retrieve socket pointer and size: %w", err)
 	}
 
-	b := make([]byte, l)
-	err = getsockname(s, unsafe.Pointer(&b[0]), &l)
-	if err != nil {
-		// although getsockname returns WSAEFAULT if the buffer is too small, it does not set
-		// &l to the correct size, so--apart from doubling the buffer repeatedly--there is no remedy
-		return err
-	}
-	return rsa.FromBytes(b[:l])
+	// although getsockname returns WSAEFAULT if the buffer is too small, it does not set
+	// &l to the correct size, so--apart from doubling the buffer repeatedly--there is no remedy
+	return getsockname(s, ptr, &l)
 }
 
 // GetPeerName returns the remote address the socket is connected to.
 //
-// See GetSockName for more information.
+// See [GetSockName] for more information.
 func GetPeerName(s windows.Handle, rsa RawSockaddr) error {
 	ptr, l, err := rsa.Sockaddr()
 	if err != nil {
-		return fmt.Errorf("could not find socket size to allocate buffer: %w", err)
-	}
-	if err = validateSockAddr(ptr, l); err != nil {
-		return err
+		return fmt.Errorf("could not retrieve socket pointer and size: %w", err)
 	}
 
-	b := make([]byte, l)
-	err = getpeername(s, unsafe.Pointer(&b[0]), &l)
-	if err != nil {
-		return err
-	}
-	return rsa.FromBytes(b[:l])
+	return getpeername(s, ptr, &l)
 }
 
 func Bind(s windows.Handle, rsa RawSockaddr) (err error) {
 	ptr, l, err := rsa.Sockaddr()
 	if err != nil {
-		return fmt.Errorf("could not find socket pointer and size: %w", err)
-	}
-	if err = validateSockAddr(ptr, l); err != nil {
-		return err
+		return fmt.Errorf("could not retrieve socket pointer and size: %w", err)
 	}
 
 	return bind(s, ptr, l)
@@ -150,7 +140,7 @@ func ConnectEx(fd windows.Handle, rsa RawSockaddr, sendBuf *byte, sendDataLen ui
 //   [in]           LPOVERLAPPED lpOverlapped
 // )
 func connectEx(s windows.Handle, name unsafe.Pointer, namelen int32, sendBuf *byte, sendDataLen uint32, bytesSent *uint32, overlapped *windows.Overlapped) (err error) {
-	// todo: after upgrading to 1.18, switch to syscall.SyscallN from syscall.Syscall9
+	// todo: after upgrading to 1.18, switch from syscall.Syscall9 to syscall.SyscallN
 	r1, _, e1 := syscall.Syscall9(connectExFunc.addr, 7, uintptr(s), uintptr(name), uintptr(namelen), uintptr(unsafe.Pointer(sendBuf)), uintptr(sendDataLen), uintptr(unsafe.Pointer(bytesSent)), uintptr(unsafe.Pointer(overlapped)), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {