xref: /dragonfly/lib/libc/net/getnetent.3 (revision 333227be) 
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32.\"     @(#)getnetent.3	8.1 (Berkeley) 6/4/93
33.\" $FreeBSD: src/lib/libc/net/getnetent.3,v 1.11.2.4 2001/12/14 18:33:55 ru Exp $
34.\" $DragonFly: src/lib/libc/net/getnetent.3,v 1.2 2003/06/17 04:26:44 dillon Exp $
35.\"
36.Dd June 4, 1993
37.Dt GETNETENT 3
38.Os
39.Sh NAME
40.Nm getnetent ,
41.Nm getnetbyaddr ,
42.Nm getnetbyname ,
43.Nm setnetent ,
44.Nm endnetent
45.Nd get network entry
46.Sh LIBRARY
47.Lb libc
48.Sh SYNOPSIS
49.In netdb.h
50.Ft struct netent *
51.Fn getnetent void
52.Ft struct netent *
53.Fn getnetbyname "const char *name"
54.Ft struct netent *
55.Fn getnetbyaddr "unsigned long net" "int type"
56.Ft void
57.Fn setnetent "int stayopen"
58.Ft void
59.Fn endnetent void
60.Sh DESCRIPTION
61The
62.Fn getnetent ,
63.Fn getnetbyname ,
64and
65.Fn getnetbyaddr
66functions
67each return a pointer to an object with the
68following structure
69containing the broken-out
70fields of a line in the network data base,
71.Pa /etc/networks .
72.Bd -literal -offset indent
73struct	netent {
74	char		*n_name;	/* official name of net */
75	char		**n_aliases;	/* alias list */
76	int		n_addrtype;	/* net number type */
77	unsigned long	n_net;		/* net number */
78};
79.Ed
80.Pp
81The members of this structure are:
82.Bl -tag -width n_addrtype
83.It Fa n_name
84The official name of the network.
85.It Fa n_aliases
86A zero terminated list of alternate names for the network.
87.It Fa n_addrtype
88The type of the network number returned; currently only AF_INET.
89.It Fa n_net
90The network number.  Network numbers are returned in machine byte
91order.
92.El
93.Pp
94The
95.Fn getnetent
96function
97reads the next line of the file, opening the file if necessary.
98.Pp
99The
100.Fn setnetent
101function
102opens and rewinds the file.  If the
103.Fa stayopen
104flag is non-zero,
105the net data base will not be closed after each call to
106.Fn getnetbyname
107or
108.Fn getnetbyaddr .
109.Pp
110The
111.Fn endnetent
112function
113closes the file.
114.Pp
115The
116.Fn getnetbyname
117function
118and
119.Fn getnetbyaddr
120sequentially search from the beginning
121of the file until a matching
122net name or
123net address and type is found,
124or until
125.Dv EOF
126is encountered.
127The
128.Fa type
129must be
130.Dv AF_INET .
131Network numbers are supplied in host order.
132.Sh FILES
133.Bl -tag -width /etc/networks -compact
134.It Pa /etc/networks
135.El
136.Sh DIAGNOSTICS
137Null pointer
138(0) returned on
139.Dv EOF
140or error.
141.Sh SEE ALSO
142.Xr networks 5
143.Pp
144.%T RFC 1101
145.Sh HISTORY
146The
147.Fn getnetent ,
148.Fn getnetbyaddr ,
149.Fn getnetbyname ,
150.Fn setnetent ,
151and
152.Fn endnetent
153functions appeared in
154.Bx 4.2 .
155.Sh BUGS
156The data space used by
157these functions is static; if future use requires the data, it should be
158copied before any subsequent calls to these functions overwrite it.
159Only Internet network
160numbers are currently understood.
161Expecting network numbers to fit
162in no more than 32 bits is probably
163naive.
164