sockcmsg_linux.go (2658B)
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 }