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