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.Dd December 7, 2020 29.Dt GETSERVENT 3 30.Os 31.Sh NAME 32.Nm getservent , 33.Nm getservbyport , 34.Nm getservbyname , 35.Nm setservent , 36.Nm endservent 37.Nd get service entry 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In netdb.h 42.Ft struct servent * 43.Fn getservent 44.Ft struct servent * 45.Fn getservbyname "const char *name" "const char *proto" 46.Ft struct servent * 47.Fn getservbyport "int port" "const char *proto" 48.Ft void 49.Fn setservent "int stayopen" 50.Ft void 51.Fn endservent void 52.Sh DESCRIPTION 53The 54.Fn getservent , 55.Fn getservbyname , 56and 57.Fn getservbyport 58functions 59each return a pointer to an object with the 60following structure 61containing the broken-out 62fields of a line in the network services data base, 63.Pa /etc/services . 64.Bd -literal -offset indent 65struct servent { 66 char *s_name; /* official name of service */ 67 char **s_aliases; /* alias list */ 68 int s_port; /* port service resides at */ 69 char *s_proto; /* protocol to use */ 70}; 71.Ed 72.Pp 73The members of this structure are: 74.Bl -tag -width s_aliases 75.It Fa s_name 76The official name of the service. 77.It Fa s_aliases 78A zero terminated list of alternate names for the service. 79.It Fa s_port 80The port number at which the service resides. 81Port numbers are returned in network byte order. 82.It Fa s_proto 83The name of the protocol to use when contacting the 84service. 85.El 86.Pp 87The 88.Fn getservent 89function 90reads the next line of the file, opening the file if necessary. 91.Pp 92The 93.Fn setservent 94function 95opens and rewinds the file. 96If the 97.Fa stayopen 98flag is non-zero, 99the net data base will not be closed after each call to 100.Fn getservbyname 101or 102.Fn getservbyport . 103.Pp 104The 105.Fn endservent 106function 107closes the file. 108.Pp 109The 110.Fn getservbyname 111and 112.Fn getservbyport 113functions 114sequentially search from the beginning 115of the file until a matching 116protocol name or 117port number (which must be specified in 118network byte order) is found, 119or until 120.Dv EOF 121is encountered. 122If a protocol name is also supplied (non- 123.Dv NULL ) , 124searches must also match the protocol. 125.Sh FILES 126.Bl -tag -width /etc/services -compact 127.It Pa /etc/services 128.It Pa /var/db/services.db 129.El 130.Sh DIAGNOSTICS 131Null pointer returned on 132.Dv EOF 133or error. 134.Sh SEE ALSO 135.Xr getprotoent 3 , 136.Xr services 5 , 137.Xr services_mkdb 8 138.Sh HISTORY 139The 140.Fn getservent , 141.Fn getservbyport , 142.Fn getservbyname , 143.Fn setservent , 144and 145.Fn endservent 146functions appeared in 147.Bx 4.2 . 148.Sh BUGS 149These functions use a thread-specific data storage; 150if the data is needed for future use, it should be 151copied before any subsequent calls overwrite it. 152Expecting port numbers to fit in a 32 bit 153quantity is probably naive. 154