1 // Copyright 2011 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4 5 // Socket control messages
6 7 package unix
8 9 import "unsafe"
10 11 // UnixCredentials encodes credentials into a socket control message
12 // for sending to another process. This can be used for
13 // authentication.
14 func UnixCredentials(ucred *Ucred) []byte {
15 b := make([]byte, CmsgSpace(SizeofUcred))
16 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
17 h.Level = SOL_SOCKET
18 h.Type = SCM_CREDENTIALS
19 h.SetLen(CmsgLen(SizeofUcred))
20 *(*Ucred)(h.data(0)) = *ucred
21 return b
22 }
23 24 // ParseUnixCredentials decodes a socket control message that contains
25 // credentials in a Ucred structure. To receive such a message, the
26 // SO_PASSCRED option must be enabled on the socket.
27 func ParseUnixCredentials(m *SocketControlMessage) (*Ucred, error) {
28 if m.Header.Level != SOL_SOCKET {
29 return nil, EINVAL
30 }
31 if m.Header.Type != SCM_CREDENTIALS {
32 return nil, EINVAL
33 }
34 ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
35 return &ucred, nil
36 }
37 38 // PktInfo4 encodes Inet4Pktinfo into a socket control message of type IP_PKTINFO.
39 func PktInfo4(info *Inet4Pktinfo) []byte {
40 b := make([]byte, CmsgSpace(SizeofInet4Pktinfo))
41 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
42 h.Level = SOL_IP
43 h.Type = IP_PKTINFO
44 h.SetLen(CmsgLen(SizeofInet4Pktinfo))
45 *(*Inet4Pktinfo)(h.data(0)) = *info
46 return b
47 }
48 49 // PktInfo6 encodes Inet6Pktinfo into a socket control message of type IPV6_PKTINFO.
50 func PktInfo6(info *Inet6Pktinfo) []byte {
51 b := make([]byte, CmsgSpace(SizeofInet6Pktinfo))
52 h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
53 h.Level = SOL_IPV6
54 h.Type = IPV6_PKTINFO
55 h.SetLen(CmsgLen(SizeofInet6Pktinfo))
56 *(*Inet6Pktinfo)(h.data(0)) = *info
57 return b
58 }
59 60 // ParseOrigDstAddr decodes a socket control message containing the original
61 // destination address. To receive such a message the IP_RECVORIGDSTADDR or
62 // IPV6_RECVORIGDSTADDR option must be enabled on the socket.
63 func ParseOrigDstAddr(m *SocketControlMessage) (Sockaddr, error) {
64 switch {
65 case m.Header.Level == SOL_IP && m.Header.Type == IP_ORIGDSTADDR:
66 pp := (*RawSockaddrInet4)(unsafe.Pointer(&m.Data[0]))
67 sa := new(SockaddrInet4)
68 p := (*[2]byte)(unsafe.Pointer(&pp.Port))
69 sa.Port = int(p[0])<<8 + int(p[1])
70 sa.Addr = pp.Addr
71 return sa, nil
72 73 case m.Header.Level == SOL_IPV6 && m.Header.Type == IPV6_ORIGDSTADDR:
74 pp := (*RawSockaddrInet6)(unsafe.Pointer(&m.Data[0]))
75 sa := new(SockaddrInet6)
76 p := (*[2]byte)(unsafe.Pointer(&pp.Port))
77 sa.Port = int(p[0])<<8 + int(p[1])
78 sa.ZoneId = pp.Scope_id
79 sa.Addr = pp.Addr
80 return sa, nil
81 82 default:
83 return nil, EINVAL
84 }
85 }
86