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prngc.c

/* $XFree86: xc/programs/xdm/prngc.c,v 1.3 2003/10/17 21:23:07 herrb Exp $ */
/*
 * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
 * Copyright (c) 2001-2002 Damien Miller.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <X11/Xos.h>
#ifndef X_NO_SYS_UN
#ifndef Lynx
#include    <sys/un.h>
#else
#include    <un.h>
#endif
#endif
#include <netinet/in.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "dm_auth.h"
#include "dm_error.h"

#ifndef INADDR_LOOPBACK
#define INADDR_LOOPBACK 0x7F000001U
#endif

static ssize_t atomicio(ssize_t (*)(), int, void *, size_t);

#ifndef offsetof
#  define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif

/*
 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
 * listening either on 'tcp_port', or via Unix domain socket at *
 * 'socket_path'.
 * Either a non-zero tcp_port or a non-null socket_path must be 
 * supplied.
 * Returns 0 on success, -1 on error
 */
int
get_prngd_bytes(char *buf, int len, 
    unsigned short tcp_port, char *socket_path)
{
      int fd, addr_len, rval, errors;
      char msg[2];
      struct sockaddr *addr;
      struct sockaddr_in addr_in;
      struct sockaddr_un addr_un;
      int af;
      void (*old_sigpipe)(int);

      /* Sanity checks */
      if (socket_path == NULL && tcp_port == 0) {
            LogError("get_random_prngd: "
                "You must specify a port or a socket\n");
            return -1;
      }
      if (socket_path != NULL &&
          strlen(socket_path) >= sizeof(addr_un.sun_path)) {
            LogError("get_random_prngd: Random pool path is too long\n");
            return -1;
      }
      if (len > 255) {
            LogError("get_random_prngd: "
                "Too many bytes to read from PRNGD\n");
            return -1;
      }

      memset(&addr_in, '\0', sizeof(addr));

      if (tcp_port != 0) {
            af = addr_in.sin_family = AF_INET;
            addr_in.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
            addr_in.sin_port = htons(tcp_port);
            addr_len = sizeof(addr_in);
            addr = (struct sockaddr *)&addr_in;
      } else {
            af = addr_un.sun_family = AF_UNIX;
            strncpy(addr_un.sun_path, socket_path,
                sizeof(addr_un.sun_path));
            addr_len = offsetof(struct sockaddr_un, sun_path) +
                strlen(socket_path) + 1;
            addr = (struct sockaddr *)&addr_un;
      }

      old_sigpipe = signal(SIGPIPE, SIG_IGN);

      errors = 0;
      rval = -1;
reopen:
      fd = socket(af, SOCK_STREAM, 0);
      if (fd == -1) {
            LogInfo("Couldn't create socket: %s\n", strerror(errno));
            goto done;
      }

      if (connect(fd, (struct sockaddr*)addr, addr_len) == -1) {
            if (af == AF_INET) {
                  LogInfo("Couldn't connect to PRNGD port %d: %s\n",
                      tcp_port, strerror(errno));
            } else {
                  LogInfo("Couldn't connect to PRNGD socket"
                      " \"%s\": %s\n",
                      addr_un.sun_path, strerror(errno));
            }
            goto done;
      }

      /* Send blocking read request to PRNGD */
      msg[0] = 0x02;
      msg[1] = len;

      if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) {
            if (errno == EPIPE && errors < 10) {
                  close(fd);
                  errors++;
                  goto reopen;
            }
            LogInfo("Couldn't write to PRNGD socket: %s\n",
                strerror(errno));
            goto done;
      }

      if (atomicio(read, fd, buf, len) != len) {
            if (errno == EPIPE && errors < 10) {
                  close(fd);
                  errors++;
                  goto reopen;
            }
            LogInfo("Couldn't read from PRNGD socket: %s\n",
                strerror(errno));
            goto done;
      }

      rval = 0;
done:
      signal(SIGPIPE, old_sigpipe);
      if (fd != -1)
            close(fd);
      return rval;
}

/*
 * ensure all of data on socket comes through. f==read || f==write
 */
static ssize_t
atomicio(ssize_t (*f)(), int fd, void *_s, size_t n)
{
      char *s = _s;
      ssize_t res, pos = 0;

      while (n > pos) {
            res = (f) (fd, s + pos, n - pos);
            switch (res) {
            case -1:
#ifdef EWOULDBLOCK
                  if (errno == EINTR || errno == EAGAIN 
                      || errno == EWOULDBLOCK)
#else
                  if (errno == EINTR || errno == EAGAIN)
#endif
                        continue;
            case 0:
                  return (res);
            default:
                  pos += res;
            }
      }
      return (pos);
}

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