You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: sockcmsg_linux.go
    path of file: ./repos/streamdal/apps/server/test-utils/grpc-client/vendor/golang.org/x/sys/unix
    
    the code of the file until where you have to start completion: // Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Socket control messages

package unix

import "unsafe"

// UnixCredentials encodes credentials into a socket control message
// for sending to another process. This can be used for
// authentication.
func UnixCredentials(ucred *Ucred) []byte {
	b := make([]byte, CmsgSpace(SizeofUcred))
	h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
	h.Level = SOL_SOCKET
	h.Type = SCM_CREDENTIALS
	h.SetLen(CmsgLen(SizeofUcred))
	*(*Ucred)(h.data(0)) = *ucred
	return b
}

// ParseUnixCredentials decodes
    
func ParseOrigDstAddr(m *SocketControlMessage) (Sockaddr, error) {
	switch {
	case m.Header.Level == SOL_IP && m.Header.Type == IP_ORIGDSTADDR:
		pp := (*RawSockaddrInet4)(unsafe.Pointer(&m.Data[0]))
		sa := new(SockaddrInet4)
		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
		sa.Port = int(p[0])<<8 + int(p[1])
		sa.Addr = pp.Addr
		return sa, nil

	case m.Header.Level == SOL_IPV6 && m.Header.Type == IPV6_ORIGDSTADDR:
		pp := (*RawSockaddrInet6)(unsafe.Pointer(&m.Data[0]))
		sa := new(SockaddrInet6)
		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
		sa.Port = int(p[0])<<8 + int(p[1])
		sa.ZoneId = pp.Scope_id
		sa.Addr = pp.Addr
		return sa, nil

	default:
		return nil, EINVAL
	}
}