xref: /dragonfly/lib/libc/net/getnetent.3 (revision 12b71966) 
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28.\"     @(#)getnetent.3	8.1 (Berkeley) 6/4/93
29.\" $FreeBSD: src/lib/libc/net/getnetent.3,v 1.23 2007/01/09 00:28:02 imp Exp $
30.\" $DragonFly: src/lib/libc/net/getnetent.3,v 1.2 2003/06/17 04:26:44 dillon Exp $
31.\"
32.Dd June 4, 1993
33.Dt GETNETENT 3
34.Os
35.Sh NAME
36.Nm getnetent ,
37.Nm getnetbyaddr ,
38.Nm getnetbyname ,
39.Nm setnetent ,
40.Nm endnetent
41.Nd get network entry
42.Sh LIBRARY
43.Lb libc
44.Sh SYNOPSIS
45.In netdb.h
46.Ft struct netent *
47.Fn getnetent void
48.Ft struct netent *
49.Fn getnetbyname "const char *name"
50.Ft struct netent *
51.Fn getnetbyaddr "uint32_t net" "int type"
52.Ft void
53.Fn setnetent "int stayopen"
54.Ft void
55.Fn endnetent void
56.Sh DESCRIPTION
57The
58.Fn getnetent ,
59.Fn getnetbyname ,
60and
61.Fn getnetbyaddr
62functions
63each return a pointer to an object with the
64following structure describing an internet network.
65This structure contains either the information obtained
66from the nameserver,
67.Xr named 8 ,
68broken-out fields of a line in the network data base
69.Pa /etc/networks ,
70or entries supplied by the
71.Xr yp 8
72system.
73The order of the lookups is controlled by the
74`networks' entry in
75.Xr nsswitch.conf 5 .
76.Pp
77.Bd -literal -offset indent
78struct	netent {
79	char		*n_name;	/* official name of net */
80	char		**n_aliases;	/* alias list */
81	int		n_addrtype;	/* net number type */
82	uint32_t	n_net;		/* net number */
83};
84.Ed
85.Pp
86The members of this structure are:
87.Bl -tag -width n_addrtype
88.It Fa n_name
89The official name of the network.
90.It Fa n_aliases
91A zero terminated list of alternate names for the network.
92.It Fa n_addrtype
93The type of the network number returned; currently only AF_INET.
94.It Fa n_net
95The network number.
96Network numbers are returned in machine byte
97order.
98.El
99.Pp
100The
101.Fn getnetent
102function
103reads the next line of the file, opening the file if necessary.
104.Pp
105The
106.Fn setnetent
107function
108opens and rewinds the file.
109If the
110.Fa stayopen
111flag is non-zero,
112the net data base will not be closed after each call to
113.Fn getnetbyname
114or
115.Fn getnetbyaddr .
116.Pp
117The
118.Fn endnetent
119function
120closes the file.
121.Pp
122The
123.Fn getnetbyname
124function
125and
126.Fn getnetbyaddr
127sequentially search from the beginning
128of the file until a matching
129net name or
130net address and type is found,
131or until
132.Dv EOF
133is encountered.
134The
135.Fa type
136argument
137must be
138.Dv AF_INET .
139Network numbers are supplied in host order.
140.Sh FILES
141.Bl -tag -width /etc/nsswitch.conf -compact
142.It Pa /etc/networks
143.It Pa /etc/nsswitch.conf
144.It Pa /etc/resolv.conf
145.El
146.Sh DIAGNOSTICS
147Null pointer
148(0) returned on
149.Dv EOF
150or error.
151.Sh SEE ALSO
152.Xr networks 5
153.Pp
154.%T RFC 1101
155.Sh HISTORY
156The
157.Fn getnetent ,
158.Fn getnetbyaddr ,
159.Fn getnetbyname ,
160.Fn setnetent ,
161and
162.Fn endnetent
163functions appeared in
164.Bx 4.2 .
165.Sh BUGS
166The data space used by
167these functions is thread-specific; if future use requires the data, it should be
168copied before any subsequent calls to these functions overwrite it.
169Only Internet network
170numbers are currently understood.
171Expecting network numbers to fit
172in no more than 32 bits is probably
173naive.
174