external/ibm-public/postfix/dist/src/util/unix_send_fd.c

   1 /*      $NetBSD: unix_send_fd.c,v 1.1.1.1 2009/06/23 10:09:01 tron Exp $        */
   2
   3 /*++
   4 /* NAME
   5 /*      unix_send_fd 3
   6 /* SUMMARY
   7 /*      send file descriptor
   8 /* SYNOPSIS
   9 /*      #include <iostuff.h>
  10 /*
  11 /*      int     unix_send_fd(fd, sendfd)
  12 /*      int     fd;
  13 /*      int     sendfd;
  14 /* DESCRIPTION
  15 /*      unix_send_fd() sends a file descriptor over the specified
  16 /*      UNIX-domain socket.
  17 /*
  18 /*      Arguments:
  19 /* .IP fd
  20 /*      File descriptor.
  21 /* .IP sendfd
  22 /*      Another file descriptor.
  23 /* DIAGNOSTICS
  24 /*      unix_send_fd() returns -1 upon failure.
  25 /* LICENSE
  26 /* .ad
  27 /* .fi
  28 /*      The Secure Mailer license must be distributed with this software.
  29 /* AUTHOR(S)
  30 /*      Wietse Venema
  31 /*      IBM T.J. Watson Research
  32 /*      P.O. Box 704
  33 /*      Yorktown Heights, NY 10598, USA
  34 /*--*/
  35
  36 /* System library. */
  37
  38 #include <sys_defs.h>                   /* includes <sys/types.h> */
  39 #include <sys/socket.h>
  40 #include <sys/uio.h>
  41 #include <string.h>
  42
  43 /* Utility library. */
  44
  45 #include <msg.h>
  46 #include <iostuff.h>
  47
  48 /* unix_send_fd - send file descriptor */
  49
  50 int     unix_send_fd(int fd, int sendfd)
  51 {
  52
  53     /*
  54      * This code does not work with version <2.2 Linux kernels, and it does
  55      * not compile with version <2 Linux libraries.
  56      */
  57 #ifdef CANT_USE_SEND_RECV_MSG
  58     const char *myname = "unix_send_fd";
  59
  60     msg_warn("%s: your system has no support for file descriptor passing",
  61              myname);
  62     return (-1);
  63 #else
  64     struct msghdr msg;
  65     struct iovec iov[1];
  66
  67     /*
  68      * Adapted from: W. Richard Stevens, UNIX Network Programming, Volume 1,
  69      * Second edition. Except that we use CMSG_LEN instead of CMSG_SPACE; the
  70      * latter breaks on LP64 systems.
  71      */
  72 #if defined(CMSG_SPACE) && !defined(NO_MSGHDR_MSG_CONTROL)
  73     union {
  74         struct cmsghdr just_for_alignment;
  75         char    control[CMSG_SPACE(sizeof(sendfd))];
  76     }       control_un;
  77     struct cmsghdr *cmptr;
  78
  79     memset((char *) &msg, 0, sizeof(msg));              /* Fix 200512 */
  80     msg.msg_control = control_un.control;
  81     msg.msg_controllen = sizeof(control_un.control);    /* Fix 200506 */
  82
  83     cmptr = CMSG_FIRSTHDR(&msg);
  84     cmptr->cmsg_len = CMSG_LEN(sizeof(sendfd));
  85     cmptr->cmsg_level = SOL_SOCKET;
  86     cmptr->cmsg_type = SCM_RIGHTS;
  87     *(int *) CMSG_DATA(cmptr) = sendfd;
  88 #else
  89     msg.msg_accrights = (char *) &sendfd;
  90     msg.msg_accrightslen = sizeof(sendfd);
  91 #endif
  92
  93     msg.msg_name = 0;
  94     msg.msg_namelen = 0;
  95
  96     /*
  97      * XXX We don't want to pass any data, just a file descriptor. However,
  98      * setting msg.msg_iov = 0 and msg.msg_iovlen = 0 causes trouble. See the
  99      * comments in the unix_recv_fd() routine.
 100      */
 101     iov->iov_base = "";
 102     iov->iov_len = 1;
 103     msg.msg_iov = iov;
 104     msg.msg_iovlen = 1;
 105
 106     return (sendmsg(fd, &msg, 0));
 107 #endif
 108 }
 109
 110 #ifdef TEST
 111
 112  /*
 113   * Proof-of-concept program. Open a file and send the descriptor, presumably
 114   * to the unix_recv_fd test program.
 115   */
 116 #include <unistd.h>
 117 #include <string.h>
 118 #include <stdlib.h>
 119 #include <fcntl.h>
 120 #include <split_at.h>
 121 #include <connect.h>
 122
 123 int     main(int argc, char **argv)
 124 {
 125     char   *transport;
 126     char   *endpoint;
 127     char   *path;
 128     int     server_sock;
 129     int     client_fd;
 130
 131     if (argc < 3
 132         || (endpoint = split_at(transport = argv[1], ':')) == 0
 133         || *endpoint == 0 || *transport == 0)
 134         msg_fatal("usage: %s transport:endpoint file...", argv[0]);
 135
 136     if (strcmp(transport, "unix") == 0) {
 137         server_sock = unix_connect(endpoint, BLOCKING, 0);
 138     } else {
 139         msg_fatal("invalid transport name: %s", transport);
 140     }
 141     if (server_sock < 0)
 142         msg_fatal("connect %s:%s: %m", transport, endpoint);
 143
 144     argv += 2;
 145     while ((path = *argv++) != 0) {
 146         if ((client_fd = open(path, O_RDONLY, 0)) < 0)
 147             msg_fatal("open %s: %m", path);
 148         msg_info("path=%s fd=%d", path, client_fd);
 149         if (unix_send_fd(server_sock, client_fd) < 0)
 150             msg_fatal("send file descriptor: %m");
 151         if (close(client_fd) != 0)
 152             msg_fatal("close(%d): %m", client_fd);
 153     }
 154     exit(0);
 155 }
 156
 157 #endif