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// 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 syscall
import (
"unsafe"
)
// Round the length of a raw sockaddr up to align it propery.
func cmsgAlignOf(salen int) int {
salign := sizeofPtr
// NOTE: It seems like 64-bit Darwin kernel still requires 32-bit
// aligned access to BSD subsystem.
if darwinAMD64 {
salign = 4
}
if salen == 0 {
return salign
}
return (salen + salign - 1) & ^(salign - 1)
}
func cmsgLen(datalen int) int {
return cmsgAlignOf(SizeofCmsghdr) + datalen
}
type SocketControlMessage struct {
Header Cmsghdr
Data []byte
}
func ParseSocketControlMessage(buf []byte) ([]SocketControlMessage, int) {
var (
h *Cmsghdr
dbuf []byte
e int
cmsgs []SocketControlMessage
)
for len(buf) >= cmsgLen(0) {
h, dbuf, e = socketControlMessageHeaderAndData(buf)
if e != 0 {
break
}
m := SocketControlMessage{}
m.Header = *h
m.Data = dbuf[:int(h.Len)-cmsgAlignOf(SizeofCmsghdr)]
cmsgs = append(cmsgs, m)
buf = buf[cmsgAlignOf(int(h.Len)):]
}
return cmsgs, e
}
func socketControlMessageHeaderAndData(buf []byte) (*Cmsghdr, []byte, int) {
h := (*Cmsghdr)(unsafe.Pointer(&buf[0]))
if h.Len < SizeofCmsghdr || int(h.Len) > len(buf) {
return nil, nil, EINVAL
}
return h, buf[cmsgAlignOf(SizeofCmsghdr):], 0
}
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