| // 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 |
| } |