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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.\" $FreeBSD$ 30.\" 31.Dd June 20, 2022 32.Dt GETNETENT 3 33.Os 34.Sh NAME 35.Nm getnetent , 36.Nm getnetbyaddr , 37.Nm getnetbyname , 38.Nm setnetent , 39.Nm endnetent 40.Nd get network entry 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In netdb.h 45.Ft struct netent * 46.Fn getnetent void 47.Ft struct netent * 48.Fn getnetbyname "const char *name" 49.Ft struct netent * 50.Fn getnetbyaddr "uint32_t net" "int type" 51.Ft void 52.Fn setnetent "int stayopen" 53.Ft void 54.Fn endnetent void 55.Ft int 56.Fn getnetent_r "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" "int *h_errnop" 57.Ft int 58.Fn getnetbyaddr_r "uint32_t net" "int type" "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" int *h_errorp" 59.Ft int 60.Fn getnetbyname_r "const char *name" "struct netent *ne" "char *buffer" "size_t buflen" "struct netent **result" "int *h_errorp" 61.Sh DESCRIPTION 62The 63.Fn getnetent , 64.Fn getnetbyname , 65and 66.Fn getnetbyaddr 67functions 68each return a pointer to an object with the 69following structure describing an internet network. 70This structure contains either the information obtained 71from the nameserver, 72.Xr named 8 , 73broken-out fields of a line in the network data base 74.Pa /etc/networks , 75or entries supplied by the 76.Xr yp 8 77system. 78The order of the lookups is controlled by the 79`networks' entry in 80.Xr nsswitch.conf 5 . 81.Bd -literal -offset indent 82struct netent { 83 char *n_name; /* official name of net */ 84 char **n_aliases; /* alias list */ 85 int n_addrtype; /* net number type */ 86 uint32_t n_net; /* net number */ 87}; 88.Ed 89.Pp 90The members of this structure are: 91.Bl -tag -width n_addrtype 92.It Fa n_name 93The official name of the network. 94.It Fa n_aliases 95A zero terminated list of alternate names for the network. 96.It Fa n_addrtype 97The type of the network number returned; currently only AF_INET. 98.It Fa n_net 99The network number. 100Network numbers are returned in machine byte 101order. 102.El 103.Pp 104The 105.Fn getnetent 106function 107reads the next line of the file, opening the file if necessary. 108.Pp 109The 110.Fn setnetent 111function 112opens and rewinds the file. 113If the 114.Fa stayopen 115flag is non-zero, 116the net data base will not be closed after each call to 117.Fn getnetbyname 118or 119.Fn getnetbyaddr . 120.Pp 121The 122.Fn endnetent 123function 124closes the file. 125.Pp 126The 127.Fn getnetbyname 128function 129and 130.Fn getnetbyaddr 131sequentially search from the beginning 132of the file until a matching 133net name or 134net address and type is found, 135or until 136.Dv EOF 137is encountered. 138The 139.Fa type 140argument 141must be 142.Dv AF_INET . 143Network numbers are supplied in host order. 144.Pp 145Functions with the 146.Em _r 147suffix provide reentrant versions of their respective counterparts. 148The caller must supply five additional parameters: a 149.Vt struct netent 150variable to be filled on success, a 151.Va buffer 152of 153.Va buflen 154bytes in size, a 155.Vt struct netent 156.Va result 157variable that will point to the result on success or be set to 158.Dv NULL 159on failure or if the name is not found. 160The 161.Va h_errnop 162variable will be filled with the error code if any. 163All these functions return 0 on success. 164.Sh FILES 165.Bl -tag -width /etc/nsswitch.conf -compact 166.It Pa /etc/networks 167.It Pa /etc/nsswitch.conf 168.It Pa /etc/resolv.conf 169.El 170.Sh DIAGNOSTICS 171Null pointer returned on 172.Dv EOF 173or error. 174.Sh SEE ALSO 175.Xr networks 5 176.Pp 177.%T RFC 1101 178.Sh HISTORY 179The 180.Fn getnetent , 181.Fn getnetbyaddr , 182.Fn getnetbyname , 183.Fn setnetent , 184and 185.Fn endnetent 186functions appeared in 187.Bx 4.2 . 188.Sh BUGS 189The data space used by 190these functions is thread-specific; if future use requires the data, it should be 191copied before any subsequent calls to these functions overwrite it. 192Only Internet network 193numbers are currently understood. 194Expecting network numbers to fit 195in no more than 32 bits is probably 196naive. 197