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.\" 3. 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.\" $FreeBSD$ 30.\" 31.Dd December 7, 2020 32.Dt GETSERVENT 3 33.Os 34.Sh NAME 35.Nm getservent , 36.Nm getservbyport , 37.Nm getservbyname , 38.Nm setservent , 39.Nm endservent 40.Nd get service entry 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In netdb.h 45.Ft struct servent * 46.Fn getservent 47.Ft struct servent * 48.Fn getservbyname "const char *name" "const char *proto" 49.Ft struct servent * 50.Fn getservbyport "int port" "const char *proto" 51.Ft void 52.Fn setservent "int stayopen" 53.Ft void 54.Fn endservent void 55.Sh DESCRIPTION 56The 57.Fn getservent , 58.Fn getservbyname , 59and 60.Fn getservbyport 61functions 62each return a pointer to an object with the 63following structure 64containing the broken-out 65fields of a line in the network services data base, 66.Pa /etc/services . 67.Bd -literal -offset indent 68struct servent { 69 char *s_name; /* official name of service */ 70 char **s_aliases; /* alias list */ 71 int s_port; /* port service resides at */ 72 char *s_proto; /* protocol to use */ 73}; 74.Ed 75.Pp 76The members of this structure are: 77.Bl -tag -width s_aliases 78.It Fa s_name 79The official name of the service. 80.It Fa s_aliases 81A zero terminated list of alternate names for the service. 82.It Fa s_port 83The port number at which the service resides. 84Port numbers are returned in network byte order. 85.It Fa s_proto 86The name of the protocol to use when contacting the 87service. 88.El 89.Pp 90The 91.Fn getservent 92function 93reads the next line of the file, opening the file if necessary. 94.Pp 95The 96.Fn setservent 97function 98opens and rewinds the file. 99If 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 (which must be specified in 121network byte order) is found, 122or until 123.Dv EOF 124is encountered. 125If a protocol name is also supplied (non- 126.Dv NULL ) , 127searches must also match the protocol. 128.Sh FILES 129.Bl -tag -width /etc/services -compact 130.It Pa /etc/services 131.It Pa /var/db/services.db 132.El 133.Sh DIAGNOSTICS 134Null pointer returned on 135.Dv EOF 136or error. 137.Sh SEE ALSO 138.Xr getprotoent 3 , 139.Xr services 5 , 140.Xr services_mkdb 8 141.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