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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.\" @(#)getnetent.3 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD: src/lib/libc/net/getnetent.3,v 1.23 2007/01/09 00:28:02 imp Exp $ 30.\" 31.Dd May 6, 2019 32.Dt GETNETENT 3 33.Os 34.Sh NAME 35.Nm getnetent , 36.Nm getnetent_r , 37.Nm getnetbyaddr , 38.Nm getnetbyaddr_r , 39.Nm getnetbyname , 40.Nm getnetbyname_r , 41.Nm setnetent , 42.Nm endnetent 43.Nd get network entry 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In netdb.h 48.Ft struct netent * 49.Fn getnetent void 50.Ft int 51.Fn getnetent_r "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" "int *h_errnop" 52.Ft struct netent * 53.Fn getnetbyname "const char *name" 54.Ft int 55.Fn getnetbyname_r "const char *name" "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" "int *h_errnop" 56.Ft struct netent * 57.Fn getnetbyaddr "uint32_t net" "int type" 58.Ft int 59.Fn getnetbyaddr_r "uint32_t addr" "int af" "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" "int *h_errnop" 60.Ft void 61.Fn setnetent "int stayopen" 62.Ft void 63.Fn endnetent void 64.Sh DESCRIPTION 65The 66.Fn getnetent , 67.Fn getnetbyname , 68and 69.Fn getnetbyaddr 70functions 71each return a pointer to an object with the 72following structure describing an internet network. 73This structure contains either the information obtained 74from the nameserver, 75.Xr named 8 , 76broken-out fields of a line in the network data base 77.Pa /etc/networks , 78or entries supplied by the 79.Xr yp 8 80system. 81The order of the lookups is controlled by the 82`networks' entry in 83.Xr nsswitch.conf 5 . 84.Bd -literal -offset indent 85struct netent { 86 char *n_name; /* official name of net */ 87 char **n_aliases; /* alias list */ 88 int n_addrtype; /* net number type */ 89 uint32_t n_net; /* net number */ 90}; 91.Ed 92.Pp 93The members of this structure are: 94.Bl -tag -width n_addrtype 95.It Fa n_name 96The official name of the network. 97.It Fa n_aliases 98A zero terminated list of alternate names for the network. 99.It Fa n_addrtype 100The type of the network number returned; currently only 101.Dv AF_INET . 102.It Fa n_net 103The network number. 104Network numbers are returned in machine byte 105order. 106.El 107.Pp 108The 109.Fn getnetent 110function 111reads the next line of the file, opening the file if necessary. 112.Pp 113The 114.Fn setnetent 115function 116opens and rewinds the file. 117If the 118.Fa stayopen 119flag is non-zero, 120the net data base will not be closed after each call to 121.Fn getnetbyname 122or 123.Fn getnetbyaddr . 124.Pp 125The 126.Fn endnetent 127function 128closes the file. 129.Pp 130The 131.Fn getnetbyname 132function 133and 134.Fn getnetbyaddr 135sequentially search from the beginning 136of the file until a matching 137net name or 138net address and type is found, 139or until 140.Dv EOF 141is encountered. 142The 143.Fa type 144argument 145must be 146.Dv AF_INET . 147Network numbers are supplied in host order. 148.Pp 149The 150.Fn getnetent_r , 151.Fn getnetbyaddr_r , 152and 153.Fn getnetbyname_r 154functions are reentrant versions of the above functions that take a 155pointer to a 156.Vt netent 157structure which is used to store state information. 158The structure must be zero-filled before it is used 159and should be considered opaque for the sake of portability. 160These functions also take a pointer to another 161.Vt netent 162structure which is used to store the results of the database lookup. 163.Sh RETURN VALUES 164The 165.Fn getnetent , 166.Fn getnetbyaddr , 167and 168.Fn getnetbyname 169functions return a pointer to a 170.Vt netent 171structure on success or a null pointer if end-of-file 172is reached or an error occurs. 173.Pp 174The 175.Fn getnetent_r , 176.Fn getnetbyaddr_r , 177and 178.Fn getnetbyname_r 179functions return 0 on success or \-1 if end-of-file 180is reached or an error occurs. 181.Sh FILES 182.Bl -tag -width ".Pa /etc/nsswitch.conf" -compact 183.It Pa /etc/networks 184.It Pa /etc/nsswitch.conf 185.It Pa /etc/resolv.conf 186.El 187.Sh SEE ALSO 188.Xr networks 5 189.Pp 190.%T RFC 1101 191.Sh STANDARDS 192The 193.Fn getnetent , 194.Fn getnetbyaddr , 195.Fn getnetbyname , 196.Fn setnetent , 197and 198.Fn endnetent 199functions conform to 200.St -p1003.1-2004 . 201.Pp 202The 203.Fn getnetent_r , 204.Fn getnetbyaddr_r , 205and 206.Fn getnetbyname_r 207functions are not currently standardized. 208.Sh HISTORY 209The 210.Fn getnetent , 211.Fn getnetbyaddr , 212.Fn getnetbyname , 213.Fn setnetent , 214and 215.Fn endnetent 216functions appeared in 217.Bx 4.2 . 218.Pp 219The 220.Fn getnetent_r , 221.Fn getnetbyaddr_r , 222and 223.Fn getnetbyname_r 224functions appeared in 225.Dx 2.1 . 226.Sh BUGS 227The data space used by 228these functions is thread-specific; if future use requires the data, it should be 229copied before any subsequent calls to these functions overwrite it. 230Only Internet network 231numbers are currently understood. 232Expecting network numbers to fit 233in no more than 32 bits is probably 234naive. 235