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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.\" 30.Dd June 27, 2022 31.Dt GETNETENT 3 32.Os 33.Sh NAME 34.Nm getnetent , 35.Nm getnetbyaddr , 36.Nm getnetbyname , 37.Nm setnetent , 38.Nm endnetent 39.Nd get network entry 40.Sh LIBRARY 41.Lb libc 42.Sh SYNOPSIS 43.In netdb.h 44.Ft struct netent * 45.Fn getnetent void 46.Ft struct netent * 47.Fn getnetbyname "const char *name" 48.Ft struct netent * 49.Fn getnetbyaddr "uint32_t net" "int type" 50.Ft void 51.Fn setnetent "int stayopen" 52.Ft void 53.Fn endnetent void 54.Ft int 55.Fn getnetent_r "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" "int *h_errnop" 56.Ft int 57.Fn getnetbyaddr_r "uint32_t net" "int type" "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" int *h_errorp" 58.Ft int 59.Fn getnetbyname_r "const char *name" "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" "int *h_errorp" 60.Sh DESCRIPTION 61The 62.Fn getnetent , 63.Fn getnetbyname , 64and 65.Fn getnetbyaddr 66functions 67each return a pointer to an object with the 68following structure describing an internet network. 69This structure contains either the information obtained 70from the nameserver, broken-out fields of a line in the network data base 71.Pa /etc/networks , 72or entries supplied by the 73.Xr yp 8 74system. 75The order of the lookups is controlled by the 76`networks' entry in 77.Xr nsswitch.conf 5 . 78.Bd -literal -offset indent 79struct netent { 80 char *n_name; /* official name of net */ 81 char **n_aliases; /* alias list */ 82 int n_addrtype; /* net number type */ 83 uint32_t n_net; /* net number */ 84}; 85.Ed 86.Pp 87The members of this structure are: 88.Bl -tag -width n_addrtype 89.It Fa n_name 90The official name of the network. 91.It Fa n_aliases 92A zero terminated list of alternate names for the network. 93.It Fa n_addrtype 94The type of the network number returned; currently only AF_INET. 95.It Fa n_net 96The network number. 97Network numbers are returned in machine byte 98order. 99.El 100.Pp 101The 102.Fn getnetent 103function 104reads the next line of the file, opening the file if necessary. 105.Pp 106The 107.Fn setnetent 108function 109opens and rewinds the file. 110If the 111.Fa stayopen 112flag is non-zero, 113the net data base will not be closed after each call to 114.Fn getnetbyname 115or 116.Fn getnetbyaddr . 117.Pp 118The 119.Fn endnetent 120function 121closes the file. 122.Pp 123The 124.Fn getnetbyname 125function 126and 127.Fn getnetbyaddr 128sequentially search from the beginning 129of the file until a matching 130net name or 131net address and type is found, 132or until 133.Dv EOF 134is encountered. 135The 136.Fa type 137argument 138must be 139.Dv AF_INET . 140Network numbers are supplied in host order. 141.Pp 142Functions with the 143.Em _r 144suffix provide reentrant versions of their respective counterparts. 145The caller must supply five additional parameters: a 146.Vt struct netent 147variable to be filled on success, a 148.Va buffer 149of 150.Va buflen 151bytes in size, a 152.Vt struct netent 153.Va result 154variable that will point to the result on success or be set to 155.Dv NULL 156on failure or if the name is not found. 157The 158.Va h_errnop 159variable will be filled with the error code if any. 160All these functions return 0 on success. 161.Sh FILES 162.Bl -tag -width /etc/nsswitch.conf -compact 163.It Pa /etc/networks 164.It Pa /etc/nsswitch.conf 165.It Pa /etc/resolv.conf 166.El 167.Sh DIAGNOSTICS 168Null pointer returned on 169.Dv EOF 170or error. 171.Sh SEE ALSO 172.Xr networks 5 173.Pp 174.%T RFC 1101 175.Sh HISTORY 176The 177.Fn getnetent , 178.Fn getnetbyaddr , 179.Fn getnetbyname , 180.Fn setnetent , 181and 182.Fn endnetent 183functions appeared in 184.Bx 4.2 . 185.Sh BUGS 186The data space used by 187these functions is thread-specific; if future use requires the data, it should be 188copied before any subsequent calls to these functions overwrite it. 189Only Internet network 190numbers are currently understood. 191Expecting network numbers to fit 192in no more than 32 bits is probably 193naive. 194