xref: /dragonfly/lib/libc/net/getservent.3 (revision 21c1c48a) 
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28.\"     From: @(#)getservent.3	8.3 (Berkeley) 1/12/94
29.\" $FreeBSD: src/lib/libc/net/getservent.3,v 1.15 2007/01/09 00:28:02 imp Exp $
30.\" $DragonFly: src/lib/libc/net/getservent.3,v 1.2 2003/06/17 04:26:44 dillon Exp $
31.\"
32.Dd July 9, 1995
33.Dt GETSERVENT 3
34.Os
35.Sh NAME
36.Nm getservent ,
37.Nm getservbyport ,
38.Nm getservbyname ,
39.Nm setservent ,
40.Nm endservent
41.Nd get service entry
42.Sh LIBRARY
43.Lb libc
44.Sh SYNOPSIS
45.In netdb.h
46.Ft struct servent *
47.Fn getservent
48.Ft struct servent *
49.Fn getservbyname "const char *name" "const char *proto"
50.Ft struct servent *
51.Fn getservbyport "int port" "const char *proto"
52.Ft void
53.Fn setservent "int stayopen"
54.Ft void
55.Fn endservent void
56.Sh DESCRIPTION
57The
58.Fn getservent ,
59.Fn getservbyname ,
60and
61.Fn getservbyport
62functions
63each return a pointer to an object with the
64following structure
65containing the broken-out
66fields of a line in the network services data base,
67.Pa /etc/services .
68.Bd -literal -offset indent
69struct	servent {
70	char	*s_name;	/* official name of service */
71	char	**s_aliases;	/* alias list */
72	int	s_port;		/* port service resides at */
73	char	*s_proto;	/* protocol to use */
74};
75.Ed
76.Pp
77The members of this structure are:
78.Bl -tag -width s_aliases
79.It Fa s_name
80The official name of the service.
81.It Fa s_aliases
82A zero terminated list of alternate names for the service.
83.It Fa s_port
84The port number at which the service resides.
85Port numbers are returned in network byte order.
86.It Fa s_proto
87The name of the protocol to use when contacting the
88service.
89.El
90.Pp
91The
92.Fn getservent
93function
94reads the next line of the file, opening the file if necessary.
95.Pp
96The
97.Fn setservent
98function
99opens and rewinds the file.
100If the
101.Fa stayopen
102flag is non-zero,
103the net data base will not be closed after each call to
104.Fn getservbyname
105or
106.Fn getservbyport .
107.Pp
108The
109.Fn endservent
110function
111closes the file.
112.Pp
113The
114.Fn getservbyname
115and
116.Fn getservbyport
117functions
118sequentially search from the beginning
119of the file until a matching
120protocol name or
121port number (which must be specified in
122network byte order) is found,
123or until
124.Dv EOF
125is encountered.
126If a protocol name is also supplied (non-
127.Dv NULL ) ,
128searches must also match the protocol.
129.Sh FILES
130.Bl -tag -width /etc/services -compact
131.It Pa /etc/services
132.El
133.Sh DIAGNOSTICS
134Null pointer
135(0) returned on
136.Dv EOF
137or error.
138.Sh SEE ALSO
139.Xr getprotoent 3 ,
140.Xr services 5
141.Sh HISTORY
142The
143.Fn getservent ,
144.Fn getservbyport ,
145.Fn getservbyname ,
146.Fn setservent ,
147and
148.Fn endservent
149functions appeared in
150.Bx 4.2 .
151.Sh BUGS
152These functions use a thread-specific data storage;
153if the data is needed for future use, it should be
154copied before any subsequent calls overwrite it.
155Expecting port numbers to fit in a 32 bit
156quantity is probably naive.
157