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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      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 copyright
     11  *    notice, this list of conditions and the following disclaimer in
     12  *    the documentation and/or other materials provided with the
     13  *    distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
     22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 #include <errno.h>
     29 #include <sys/types.h>
     30 #include <sys/socket.h>
     31 #include <netinet/in.h>
     32 #include <string.h>
     33 #include <unistd.h>
     34 
     35 #define START_PORT	600
     36 #define END_PORT	IPPORT_RESERVED
     37 #define NUM_PORTS	(END_PORT - START_PORT)
     38 
     39 int bindresvport(int sd, struct sockaddr_in *sin)
     40 {
     41     static short        port;
     42     struct sockaddr_in  sin0;
     43     int                 nn, ret;
     44 
     45     if (sin == NULL) {
     46         sin = &sin0;
     47         memset( sin, 0, sizeof *sin );
     48         sin->sin_family = AF_INET;
     49     } else if (sin->sin_family != AF_INET) {
     50         errno = EPFNOSUPPORT;
     51         return -1;
     52     }
     53 
     54     if (port == 0) {
     55         port = START_PORT + (getpid() % NUM_PORTS);
     56     }
     57 
     58     for (nn = NUM_PORTS; nn > 0; nn--, port++)
     59     {
     60         if (port == END_PORT)
     61             port = START_PORT;
     62 
     63         sin->sin_port = htons(port);
     64         do {
     65             ret = bind(sd, (struct sockaddr*)sin, sizeof(*sin));
     66         } while (ret < 0 && errno == EINTR);
     67 
     68         if (!ret)
     69             break;
     70     }
     71     return ret;
     72 }
     73