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52 .\" $FreeBSD: src/lib/libutil/realhostname_sa.3,v 1.11 2005/02/13 22:25:14 ru Exp $
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54 .Dd January 11, 2000
55 .Os
56 .Dt REALHOSTNAME_SA 3
57 .Sh NAME
58 .Nm realhostname_sa
59 .Nd "convert a"
60 .Vt "struct sockaddr"
61 to the real host name
62 .Sh LIBRARY
63 .Lb libutil
64 .Sh SYNOPSIS
65 .In sys/types.h
66 .In netinet/in.h
67 .In libutil.h
68 .Ft int
69 .Fn realhostname_sa "char *host" "size_t hsize" "struct sockaddr *addr" "int addrlen"
70 .Sh DESCRIPTION
71 The function
72 .Fn realhostname_sa
73 converts
74 .Ar addr
75 to the corresponding host name.
76 This is done by resolving
77 .Ar addr
78 to a host name and then ensuring that the host name resolves
79 back to
80 .Ar addr .
81 .Pp
82 .Ar host
83 must point to a buffer of at least
84 .Ar hsize
85 bytes, and will always be written to by this function.
86 .Pp
87 If the name resolution does not work both ways or if the host name is longer
88 than
89 .Ar hsize
90 bytes,
91 .Xr getnameinfo 3
92 with NI_NUMERICHOST specified, is used to convert
93 .Ar addr
94 to an ASCII form.
95 .Pp
96 If the string written to
97 .Ar host
98 is
99 .Ar hsize
100 bytes long,
101 .Ar host
102 will not be NUL terminated.
103 .Sh RETURN VALUES
104 The
105 .Fn realhostname_sa
106 function will return one of the following constants which are defined in
107 .In libutil.h :
108 .Pp
109 .Bl -tag -width XXX -offset XXX
110 .It Li HOSTNAME_FOUND
111 A valid host name was found.
112 .It Li HOSTNAME_INCORRECTNAME
113 A host name was found, but it did not resolve back to the passed
114 .Ar ip .
115 .Ar host
116 now contains the numeric value of
117 .Ar ip .
118 .It Li HOSTNAME_INVALIDADDR
119 .Ar ip
120 could not be resolved.
121 .Ar host
122 now contains the numeric value of
123 .Ar ip .
124 .It Li HOSTNAME_INVALIDNAME
125 A host name was found, but it could not be resolved back to any ip number.
126 .Ar host
127 now contains the numeric value of
128 .Ar ip .
129 .El
130 .Sh SEE ALSO
131 .Xr getaddrinfo 3 ,
132 .Xr getnameinfo 3 ,
133 .Xr realhostname 3