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

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      upass_connect 3
   6 /* SUMMARY
   7 /*      connect to UNIX-domain file descriptor listener
   8 /* SYNOPSIS
   9 /*      #include <connect.h>
  10 /*
  11 /*      int     upass_connect(addr, block_mode, timeout)
  12 /*      const char *addr;
  13 /*      int     block_mode;
  14 /*      int     timeout;
  15 /* DESCRIPTION
  16 /*      upass_connect() connects to a file descriptor listener in
  17 /*      the UNIX domain at the specified address, sends one half
  18 /*      of a socketpair to the listener, and returns the other half
  19 /*      to the caller.
  20 /*
  21 /*      The file descriptor transporting connection is closed by
  22 /*      a background thread. Some kernels might otherwise discard
  23 /*      the descriptor before the server has received it.
  24 /*
  25 /*      Arguments:
  26 /* .IP addr
  27 /*      Null-terminated string with connection destination.
  28 /* .IP block_mode
  29 /*      Either NON_BLOCKING for a non-blocking socket, or BLOCKING for
  30 /*      blocking mode. This setting has no effect on the connection
  31 /*      establishment process.
  32 /* .IP timeout
  33 /*      Bounds the number of seconds that the operation may take. Specify
  34 /*      a value <= 0 to disable the time limit.
  35 /* DIAGNOSTICS
  36 /*      The result is -1 in case the connection could not be made.
  37 /*      Fatal errors: other system call failures.
  38 /* LICENSE
  39 /* .ad
  40 /* .fi
  41 /*      The Secure Mailer license must be distributed with this software.
  42 /* AUTHOR(S)
  43 /*      Wietse Venema
  44 /*      IBM T.J. Watson Research
  45 /*      P.O. Box 704
  46 /*      Yorktown Heights, NY 10598, USA
  47 /*--*/
  48
  49 /* System interfaces. */
  50
  51 #include <sys_defs.h>
  52 #include <sys/socket.h>
  53 #include <sys/un.h>
  54 #include <string.h>
  55 #include <unistd.h>
  56 #include <errno.h>
  57
  58 /* Utility library. */
  59
  60 #include <msg.h>
  61 #include <iostuff.h>
  62 #include <sane_connect.h>
  63 #include <connect.h>
  64 #include <timed_connect.h>
  65 #include <events.h>
  66 #include <mymalloc.h>
  67 #include <sane_socketpair.h>
  68
  69  /*
  70   * Workaround for hostile kernels that don't support graceful shutdown.
  71   */
  72 struct upass_connect {
  73     int     fd;
  74     char   *service;
  75 };
  76
  77 /* upass_connect_event - disconnect from peer */
  78
  79 static void upass_connect_event(int event, char *context)
  80 {
  81     struct upass_connect *up = (struct upass_connect *) context;
  82     static const char *myname = "upass_connect_event";
  83
  84     /*
  85      * Disconnect.
  86      */
  87     if (event == EVENT_TIME)
  88         msg_warn("%s: read timeout for service %s", myname, up->service);
  89     event_disable_readwrite(up->fd);
  90     event_cancel_timer(upass_connect_event, context);
  91     if (close(up->fd) < 0)
  92         msg_warn("%s: close %s: %m", myname, up->service);
  93     myfree(up->service);
  94     myfree((char *) up);
  95 }
  96
  97 /* upass_connect - connect to UNIX-domain file descriptor listener */
  98
  99 int     upass_connect(const char *addr, int block_mode, int timeout)
 100 {
 101     struct upass_connect *up;
 102     int     pair[2];
 103     int     sock;
 104
 105     /*
 106      * Connect.
 107      */
 108     if ((sock = unix_connect(addr, BLOCKING, timeout)) < 0)
 109         return (-1);
 110
 111     /*
 112      * Send one socket pair half to the server.
 113      */
 114 #define OUR_HALF        0
 115 #define THEIR_HALF      1
 116
 117     if (sane_socketpair(AF_UNIX, SOCK_STREAM, 0, pair) < 0) {
 118         close(sock);
 119         return (-1);
 120     }
 121     if (unix_send_fd(sock, pair[THEIR_HALF]) < 0) {
 122         close(pair[THEIR_HALF]);
 123         close(pair[OUR_HALF]);
 124         close(sock);
 125         return (-1);
 126     }
 127     close(pair[THEIR_HALF]);
 128
 129     /*
 130      * Return the other socket pair half to the caller. Don't close the
 131      * control socket just yet, but wait until the receiver closes it first.
 132      * Otherwise, some hostile kernel might discard the socket that we just
 133      * sent.
 134      */
 135     up = (struct upass_connect *) mymalloc(sizeof(*up));
 136     up->fd = sock;
 137     up->service = mystrdup(addr);
 138     if (timeout > 0)
 139         event_request_timer(upass_connect_event, (char *) up, timeout + 100);
 140     event_enable_read(sock, upass_connect_event, (char *) up);
 141     non_blocking(pair[OUR_HALF], block_mode);
 142     return (pair[OUR_HALF]);
 143 }