gen.subproj/getnetent.3

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  32 .\"     @(#)getnetent.3 8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/net/getnetent.3,v 1.11.2.3 2001/08/17 15:42:38 ru Exp $
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  35 .Dd June 4, 1993
  36 .Dt GETNETENT 3
  37 .Os
  38 .Sh NAME
  39 .Nm endnetent ,
  40 .Nm getnetbyaddr ,
  41 .Nm getnetbyname ,
  42 .Nm getnetent ,
  43 .Nm setnetent
  44 .Nd get network entry
  45 .Sh LIBRARY
  46 .Lb libc
  47 .Sh SYNOPSIS
  48 .Fd #include <netdb.h>
  49 .Ft void
  50 .Fo endnetent
  51 .Fa void
  52 .Fc
  53 .Ft struct netent *
  54 .Fo getnetbyaddr
  55 .Fa "uint32_t net"
  56 .Fa "int type"
  57 .Fc
  58 .Ft struct netent *
  59 .Fo getnetbyname
  60 .Fa "const char *name"
  61 .Fc
  62 .Ft struct netent *
  63 .Fo getnetent
  64 .Fa void
  65 .Fc
  66 .Ft void
  67 .Fo setnetent
  68 .Fa "int stayopen"
  69 .Fc
  70 .Sh DESCRIPTION
  71 The
  72 .Fn getnetent ,
  73 .Fn getnetbyname ,
  74 and
  75 .Fn getnetbyaddr
  76 functions
  77 each return a pointer to an object with the
  78 following structure
  79 containing the broken-out
  80 fields of a line in the network data base,
  81 .Pa /etc/networks .
  82 .Bd -literal -offset indent
  83 struct  netent {
  84         char            *n_name;        /* official name of net */
  85         char            **n_aliases;    /* alias list */
  86         int             n_addrtype;     /* net number type */
  87         unsigned long   n_net;          /* net number */
  88 };
  89 .Ed
  90 .Pp
  91 The members of this structure are:
  92 .Bl -tag -width n_addrtype
  93 .It Fa n_name
  94 The official name of the network.
  95 .It Fa n_aliases
  96 A zero terminated list of alternate names for the network.
  97 .It Fa n_addrtype
  98 The type of the network number returned; currently only AF_INET.
  99 .It Fa n_net
 100 The network number.  Network numbers are returned in machine byte
 101 order.
 102 .El
 103 .Pp
 104 The
 105 .Fn getnetent
 106 function
 107 reads the next line of the file, opening the file if necessary.
 108 .Pp
 109 The
 110 .Fn setnetent
 111 function
 112 opens and rewinds the file.  If the
 113 .Fa stayopen
 114 flag is non-zero,
 115 the net data base will not be closed after each call to
 116 .Fn getnetbyname
 117 or
 118 .Fn getnetbyaddr .
 119 .Pp
 120 The
 121 .Fn endnetent
 122 function
 123 closes the file.
 124 .Pp
 125 The
 126 .Fn getnetbyname
 127 function
 128 and
 129 .Fn getnetbyaddr
 130 sequentially search from the beginning
 131 of the file until a matching
 132 net name or
 133 net address and type is found,
 134 or until
 135 .Dv EOF
 136 is encountered.
 137 The
 138 .Fa type
 139 must be
 140 .Dv AF_INET .
 141 Network numbers are supplied in host order.
 142 .Sh FILES
 143 .Bl -tag -width /etc/networks -compact
 144 .It Pa /etc/networks
 145 .El
 146 .Sh DIAGNOSTICS
 147 Null pointer
 148 (0) returned on
 149 .Dv EOF
 150 or error.
 151 .Sh SEE ALSO
 152 .Xr networks 5
 153 .Pp
 154 .%T RFC 1101
 155 .Sh HISTORY
 156 The
 157 .Fn getnetent ,
 158 .Fn getnetbyaddr ,
 159 .Fn getnetbyname ,
 160 .Fn setnetent ,
 161 and
 162 .Fn endnetent
 163 functions appeared in
 164 .Bx 4.2 .
 165 .Sh BUGS
 166 The data space used by
 167 these functions is static; if future use requires the data, it should be
 168 copied before any subsequent calls to these functions overwrite it.
 169 Only Internet network
 170 numbers are currently understood.
 171 Expecting network numbers to fit
 172 in no more than 32 bits is probably
 173 naive.