xref: /dragonfly/lib/libc/net/getnetent.3 (revision 3851e4b8) 
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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.Bd -literal -offset indent
77struct	netent {
78	char		*n_name;	/* official name of net */
79	char		**n_aliases;	/* alias list */
80	int		n_addrtype;	/* net number type */
81	uint32_t	n_net;		/* net number */
82};
83.Ed
84.Pp
85The members of this structure are:
86.Bl -tag -width n_addrtype
87.It Fa n_name
88The official name of the network.
89.It Fa n_aliases
90A zero terminated list of alternate names for the network.
91.It Fa n_addrtype
92The type of the network number returned; currently only AF_INET.
93.It Fa n_net
94The network number.
95Network numbers are returned in machine byte
96order.
97.El
98.Pp
99The
100.Fn getnetent
101function
102reads the next line of the file, opening the file if necessary.
103.Pp
104The
105.Fn setnetent
106function
107opens and rewinds the file.
108If the
109.Fa stayopen
110flag is non-zero,
111the net data base will not be closed after each call to
112.Fn getnetbyname
113or
114.Fn getnetbyaddr .
115.Pp
116The
117.Fn endnetent
118function
119closes the file.
120.Pp
121The
122.Fn getnetbyname
123function
124and
125.Fn getnetbyaddr
126sequentially search from the beginning
127of the file until a matching
128net name or
129net address and type is found,
130or until
131.Dv EOF
132is encountered.
133The
134.Fa type
135argument
136must be
137.Dv AF_INET .
138Network numbers are supplied in host order.
139.Sh FILES
140.Bl -tag -width /etc/nsswitch.conf -compact
141.It Pa /etc/networks
142.It Pa /etc/nsswitch.conf
143.It Pa /etc/resolv.conf
144.El
145.Sh DIAGNOSTICS
146Null pointer
147(0) returned on
148.Dv EOF
149or error.
150.Sh SEE ALSO
151.Xr networks 5
152.Pp
153.%T RFC 1101
154.Sh HISTORY
155The
156.Fn getnetent ,
157.Fn getnetbyaddr ,
158.Fn getnetbyname ,
159.Fn setnetent ,
160and
161.Fn endnetent
162functions appeared in
163.Bx 4.2 .
164.Sh BUGS
165The data space used by
166these functions is thread-specific; if future use requires the data, it should be
167copied before any subsequent calls to these functions overwrite it.
168Only Internet network
169numbers are currently understood.
170Expecting network numbers to fit
171in no more than 32 bits is probably
172naive.
173