1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 4. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 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