sunrpc/bindrsvprt.c

   1 /*
   2  * Copyright (c) 1987 by Sun Microsystems, Inc.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  *     * Redistributions of source code must retain the above copyright
   9  *       notice, this list of conditions and the following disclaimer.
  10  *     * Redistributions in binary form must reproduce the above
  11  *       copyright notice, this list of conditions and the following
  12  *       disclaimer in the documentation and/or other materials
  13  *       provided with the distribution.
  14  *     * Neither the name of Sun Microsystems, Inc. nor the names of its
  15  *       contributors may be used to endorse or promote products derived
  16  *       from this software without specific prior written permission.
  17  *
  18  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  21  *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  22  *   COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  23  *   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  *   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  25  *   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  27  *   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  28  *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  29  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include <errno.h>
  33 #include <unistd.h>
  34 #include <string.h>
  35 #include <sys/types.h>
  36 #include <sys/socket.h>
  37 #include <netinet/in.h>
  38
  39 /*
  40  * Bind a socket to a privileged IP port
  41  */
  42 int
  43 bindresvport (int sd, struct sockaddr_in *sin)
  44 {
  45   static short port;
  46   struct sockaddr_in myaddr;
  47   int i;
  48
  49 #define STARTPORT 600
  50 #define LOWPORT 512
  51 #define ENDPORT (IPPORT_RESERVED - 1)
  52 #define NPORTS  (ENDPORT - STARTPORT + 1)
  53   static short startport = STARTPORT;
  54
  55   if (sin == (struct sockaddr_in *) 0)
  56     {
  57       sin = &myaddr;
  58       __bzero (sin, sizeof (*sin));
  59       sin->sin_family = AF_INET;
  60     }
  61   else if (sin->sin_family != AF_INET)
  62     {
  63       __set_errno (EAFNOSUPPORT);
  64       return -1;
  65     }
  66
  67   if (port == 0)
  68     {
  69       port = (__getpid () % NPORTS) + STARTPORT;
  70     }
  71
  72   /* Initialize to make gcc happy.  */
  73   int res = -1;
  74
  75   int nports = ENDPORT - startport + 1;
  76   int endport = ENDPORT;
  77  again:
  78   for (i = 0; i < nports; ++i)
  79     {
  80       sin->sin_port = htons (port++);
  81       if (port > endport)
  82         port = startport;
  83       res = __bind (sd, sin, sizeof (struct sockaddr_in));
  84       if (res >= 0 || errno != EADDRINUSE)
  85         break;
  86     }
  87
  88   if (i == nports && startport != LOWPORT)
  89     {
  90       startport = LOWPORT;
  91       endport = STARTPORT - 1;
  92       nports = STARTPORT - LOWPORT;
  93       port = LOWPORT + port % (STARTPORT - LOWPORT);
  94       goto again;
  95     }
  96
  97   return res;
  98 }
  99 libc_hidden_def (bindresvport)