Add UnixCredentials system call for DragonFly BSD

Author: varialus

transport_unixcred_dragonfly.go

@@ -0,0 +1,95 @@
+// The UnixCredentials system call is currently only implemented on Linux
+// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
+// https://groups.google.com/forum/#!topic/golang-dev/z7VbyqR1s78
+// http://code.google.com/p/go/source/browse/unix/sockcmsg_linux.go?repo=sys
+
+// Local implementation of the UnixCredentials system call for DragonFly BSD
+
+package dbus
+
+/*
+#include <sys/ucred.h>
+*/
+import "C"
+
+import (
+	"io"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+// http://golang.org/src/pkg/syscall/ztypes_linux_amd64.go
+// http://golang.org/src/pkg/syscall/ztypes_dragonfly_amd64.go
+type Ucred struct {
+	Pid int32
+	Uid uint32
+	Gid uint32
+}
+
+// http://golang.org/src/pkg/syscall/types_linux.go
+// http://golang.org/src/pkg/syscall/types_dragonfly.go
+// https://github.com/DragonFlyBSD/DragonFlyBSD/blob/master/sys/sys/ucred.h
+const (
+	SizeofUcred = C.sizeof_struct_ucred
+)
+
+// http://golang.org/src/pkg/syscall/sockcmsg_unix.go
+func cmsgAlignOf(salen int) int {
+	// From http://golang.org/src/pkg/syscall/sockcmsg_unix.go
+	//salign := sizeofPtr
+	// NOTE: It seems like 64-bit Darwin and DragonFly BSD kernels
+	// still require 32-bit aligned access to network subsystem.
+	//if darwin64Bit || dragonfly64Bit {
+	//	salign = 4
+	//}
+	salign := 4
+	return (salen + salign - 1) & ^(salign - 1)
+}
+
+// http://golang.org/src/pkg/syscall/sockcmsg_unix.go
+func cmsgData(h *syscall.Cmsghdr) unsafe.Pointer {
+	return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(syscall.SizeofCmsghdr)))
+}
+
+// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
+// 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, syscall.CmsgSpace(SizeofUcred))
+	h := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
+	h.Level = syscall.SOL_SOCKET
+	h.Type = syscall.SCM_CREDS
+	h.SetLen(syscall.CmsgLen(SizeofUcred))
+	*((*Ucred)(cmsgData(h))) = *ucred
+	return b
+}
+
+// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
+// ParseUnixCredentials decodes a socket control message that contains
+// credentials in a Ucred structure. To receive such a message, the
+// SO_PASSCRED option must be enabled on the socket.
+func ParseUnixCredentials(m *syscall.SocketControlMessage) (*Ucred, error) {
+	if m.Header.Level != syscall.SOL_SOCKET {
+		return nil, syscall.EINVAL
+	}
+	if m.Header.Type != syscall.SCM_CREDS {
+		return nil, syscall.EINVAL
+	}
+	ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
+	return &ucred, nil
+}
+
+func (t *unixTransport) SendNullByte() error {
+	ucred := &Ucred{Pid: int32(os.Getpid()), Uid: uint32(os.Getuid()), Gid: uint32(os.Getgid())}
+	b := UnixCredentials(ucred)
+	_, oobn, err := t.UnixConn.WriteMsgUnix([]byte{0}, b, nil)
+	if err != nil {
+		return err
+	}
+	if oobn != len(b) {
+		return io.ErrShortWrite
+	}
+	return nil
+}

transport_unixcred.go renamed to transport_unixcred_linux.go

@@ -1,4 +1,7 @@
-// +build !darwin,!windows
+// The UnixCredentials system call is currently only implemented on Linux
+// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
+// https://groups.google.com/forum/#!topic/golang-dev/z7VbyqR1s78
+// http://code.google.com/p/go/source/browse/unix/sockcmsg_linux.go?repo=sys
 
 package dbus