1.\" $NetBSD: getservent.3,v 1.17 2024/09/07 21:04:43 rillig Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)getservent.3 8.4 (Berkeley) 5/25/95 31.\" 32.Dd December 3, 2022 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 NULL terminated list of alternative names for the service. 83.It Fa s_port 84The port number at which the service resides. 85Port numbers must be given and 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. If the 100.Fa stayopen 101flag is non-zero, 102the net data base will not be closed after each call to 103.Fn getservbyname 104or 105.Fn getservbyport . 106.Pp 107The 108.Fn endservent 109function 110closes the file. 111.Pp 112The 113.Fn getservbyname 114and 115.Fn getservbyport 116functions 117sequentially search from the beginning 118of the file until a matching 119protocol name or 120port number is found, 121or until 122.Dv EOF 123is encountered. 124If a protocol name is also supplied (non-\c 125.Dv NULL ) , 126searches must also match the protocol. 127.Sh FILES 128.Bl -tag -width /etc/services -compact 129.It Pa /etc/services 130.It Pa /var/db/services.cdb 131.El 132.Sh RETURN VALUES 133Null pointer is returned on 134.Dv EOF 135or error. 136.Sh SEE ALSO 137.Xr getprotoent 3 , 138.Xr services 5 , 139.Xr services_mkdb 8 140.Sh HISTORY 141The 142.Fn getservent , 143.Fn getservbyport , 144.Fn getservbyname , 145.Fn setservent , 146and 147.Fn endservent 148functions appeared in 149.Bx 4.2 . 150.Sh BUGS 151These functions use static data storage; 152if the data is needed for future use, it should be 153copied before any subsequent calls overwrite it. 154Expecting port numbers to fit in a 32 bit 155quantity is probably naive. 156