gen.subproj/getservent.3

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  32 .\"     From: @(#)getservent.3  8.3 (Berkeley) 1/12/94
  33 .\" $FreeBSD: src/lib/libc/net/getservent.3,v 1.7.2.4 2001/08/17 15:42:38 ru Exp $
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  35 .Dd July 9, 1995
  36 .Dt GETSERVENT 3
  37 .Os
  38 .Sh NAME
  39 .Nm endservent ,
  40 .Nm getservbyname ,
  41 .Nm getservbyport ,
  42 .Nm getservent ,
  43 .Nm setservent
  44 .Nd get service entry
  45 .Sh LIBRARY
  46 .Lb libc
  47 .Sh SYNOPSIS
  48 .Fd #include <netdb.h>
  49 .Ft void
  50 .Fo endservent
  51 .Fa void
  52 .Fc
  53 .Ft struct servent *
  54 .Fo getservbyname
  55 .Fa "const char *name"
  56 .Fa "const char *proto"
  57 .Fc
  58 .Ft struct servent *
  59 .Fo getservbyport
  60 .Fa "int port"
  61 .Fa "const char *proto"
  62 .Fc
  63 .Ft struct servent *
  64 .Fo getservent
  65 .Fa void
  66 .Fc
  67 .Ft void
  68 .Fo setservent
  69 .Fa "int stayopen"
  70 .Fc
  71 .Sh DESCRIPTION
  72 The
  73 .Fn getservent ,
  74 .Fn getservbyname ,
  75 and
  76 .Fn getservbyport
  77 functions
  78 each return a pointer to an object with the
  79 following structure
  80 containing the broken-out
  81 fields of a line in the network services data base,
  82 .Pa /etc/services .
  83 .Bd -literal -offset indent
  84 struct  servent {
  85         char    *s_name;        /* official name of service */
  86         char    **s_aliases;    /* alias list */
  87         int     s_port;         /* port service resides at */
  88         char    *s_proto;       /* protocol to use */
  89 };
  90 .Ed
  91 .Pp
  92 The members of this structure are:
  93 .Bl -tag -width s_aliases
  94 .It Fa s_name
  95 The official name of the service.
  96 .It Fa s_aliases
  97 A zero terminated list of alternate names for the service.
  98 .It Fa s_port
  99 The port number at which the service resides.
 100 Port numbers are returned in network byte order.
 101 .It Fa s_proto
 102 The name of the protocol to use when contacting the
 103 service.
 104 .El
 105 .Pp
 106 The
 107 .Fn getservent
 108 function
 109 reads the next line of the file, opening the file if necessary.
 110 .Pp
 111 The
 112 .Fn setservent
 113 function
 114 opens and rewinds the file.  If the
 115 .Fa stayopen
 116 flag is non-zero,
 117 the net data base will not be closed after each call to
 118 .Fn getservbyname
 119 or
 120 .Fn getservbyport .
 121 .Pp
 122 The
 123 .Fn endservent
 124 function
 125 closes the file.
 126 .Pp
 127 The
 128 .Fn getservbyname
 129 and
 130 .Fn getservbyport
 131 functions
 132 sequentially search from the beginning
 133 of the file until a matching
 134 protocol name or
 135 port number (which must be specified in
 136 network byte order) is found,
 137 or until
 138 .Dv EOF
 139 is encountered.
 140 If a protocol name is also supplied (non-
 141 .Dv NULL ) ,
 142 searches must also match the protocol.
 143 .Sh FILES
 144 .Bl -tag -width /etc/services -compact
 145 .It Pa /etc/services
 146 .El
 147 .Sh DIAGNOSTICS
 148 Null pointer
 149 (0) returned on
 150 .Dv EOF
 151 or error.
 152 .Sh SEE ALSO
 153 .Xr getprotoent 3 ,
 154 .Xr services 5
 155 .Sh HISTORY
 156 The
 157 .Fn getservent ,
 158 .Fn getservbyport ,
 159 .Fn getservbyname ,
 160 .Fn setservent ,
 161 and
 162 .Fn endservent
 163 functions appeared in
 164 .Bx 4.2 .
 165 .Sh BUGS
 166 These functions use static data storage;
 167 if the data is needed for future use, it should be
 168 copied before any subsequent calls overwrite it.
 169 Expecting port numbers to fit in a 32 bit
 170 quantity is probably naive.