/*
 * ProFTPD - FTP server daemon
 * Copyright (c) 1997, 1998 Public Flood Software
 * Copyright (c) 1999, 2000 MacGyver aka Habeeb J. Dihu <macgyver@tos.net>
 * Copyright (c) 2001-2005 The ProFTPD Project team
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA.
 *
 * As a special exemption, Public Flood Software/MacGyver aka Habeeb J. Dihu
 * and other respective copyright holders give permission to link this program
 * with OpenSSL, and distribute the resulting executable, without including
 * the source code for OpenSSL in the source distribution.
 */

/* Inet support functions, many wrappers for netdb functions
 * $Id: inet.c,v 1.97 2006/09/29 16:38:16 castaglia Exp $
 */

#include "conf.h"
#include "privs.h"

extern server_rec *main_server;

/* A private work pool for all pr_inet_* functions to use. */
static pool *inet_pool = NULL;

static int ip_proto = IPPROTO_IP;
#ifdef PR_USE_IPV6
static int ipv6_proto = IPPROTO_IPV6;
#endif /* PR_USE_IPV6 */
static int tcp_proto = IPPROTO_TCP;

static int inet_errno = 0;		/* Holds errno */

/* The default address family to use when creating a socket, if a pr_netaddr_t
 * is not given.  This is mainly for the benefit of initialize_connection().
 */
static int inet_family = 0;

/* Called by others after running a number of pr_inet_* functions in order
 * to free up memory.
 */
void pr_inet_clear(void) {
  destroy_pool(inet_pool);
  inet_pool = NULL;
}

/* All inet_ interface functions take a pool as the first arg, which
 * is where any returned allocated memory is taken from.  For purposes
 * of uniformity the pool is included in all calls, even those that
 * don't need to return allocated memory.
 */

int pr_inet_set_default_family(pool *p, int family) {
  int old_family = inet_family;
  inet_family = family;
  return old_family;
}

/* Find a service and return its port number. */
int pr_inet_getservport(pool *p, const char *serv, const char *proto) {
  struct servent *servent = getservbyname(serv, proto);

  /* getservbyname returns the port in network byte order. */
  return (servent ? ntohs(servent->s_port) : -1);
}

/* Validate anything returned from the 'outside', since it's untrusted
 * information.
 */
char *pr_inet_validate(char *buf) {
  char *p;

  /* Validate anything returned from a DNS.
   */
  for (p = buf; p && *p; p++) {

    /* Per RFC requirements, these are all that are valid from a DNS. */
    if (!isalnum((int) *p) && *p != '.' && *p != '-'
#ifdef PR_USE_IPV6
        && *p != ':'
#endif /* PR_USE_IPV6 */
        ) {

      /* We set it to _ because we know that's an invalid, yet safe, option
       * for a DNS entry.
       */
      *p = '_';
    }
  }

  return buf;
}

static void conn_cleanup_cb(void *cv) {
  conn_t *c = (conn_t *) cv;

  if (c->instrm)
    pr_netio_close(c->instrm);

  if (c->outstrm && c->outstrm != c->instrm)
    pr_netio_close(c->outstrm);

  if (c->listen_fd != -1)
    close(c->listen_fd);

  if (c->rfd != -1)
    close(c->rfd);

  if (c->wfd != -1)
    close(c->wfd);
}

/* Copy a connection structure, also creates a sub pool for the new
 * connection.
 */
conn_t *pr_inet_copy_connection(pool *p, conn_t *c) {
  conn_t *res = NULL;
  pool *sub_pool = NULL;

  sub_pool = make_sub_pool(p);
  pr_pool_tag(sub_pool, "pr_inet_copy_connection() subpool");

  res = (conn_t *) pcalloc(sub_pool,sizeof(conn_t));

  memcpy(res, c, sizeof(conn_t));
  res->pool = sub_pool;
  res->instrm = res->outstrm = NULL;

  if (c->local_addr) {
    res->local_addr = pr_netaddr_alloc(res->pool);

    pr_netaddr_set_family(res->local_addr,
      pr_netaddr_get_family(c->local_addr));
    pr_netaddr_set_sockaddr(res->local_addr,
      pr_netaddr_get_sockaddr(c->local_addr));
  }

  if (c->remote_addr) {
    res->remote_addr = pr_netaddr_alloc(res->pool);

    pr_netaddr_set_family(res->remote_addr,
      pr_netaddr_get_family(c->remote_addr));
    pr_netaddr_set_sockaddr(res->remote_addr,
      pr_netaddr_get_sockaddr(c->remote_addr));
  }

  if (c->remote_name)
    res->remote_name = pstrdup(res->pool, c->remote_name);

  register_cleanup(res->pool, (void *) res, conn_cleanup_cb, conn_cleanup_cb);
  return res;
}

/* Initialize a new connection record, also creates a new subpool just for the
 * new connection.
 */
static conn_t *inet_initialize_connection(pool *p, xaset_t *servers, int fd,
    pr_netaddr_t *bind_addr, int port, int retry_bind, int reporting) {
  pool *sub_pool = NULL;
  conn_t *c;
  pr_netaddr_t na;
  int addr_family;
  int res = 0, one = 1, hold_errno;

  if ((!servers || !servers->xas_list) && !main_server) {
    errno = EINVAL;
    return NULL;
  }

  if (!inet_pool) {
    inet_pool = make_sub_pool(permanent_pool);
    pr_pool_tag(inet_pool, "Inet Pool");
  }

  /* Initialize the netaddr. */
  pr_netaddr_clear(&na);

  sub_pool = make_sub_pool(p);
  pr_pool_tag(sub_pool, "inet_initialize_connection() subpool");

  c = (conn_t *) pcalloc(sub_pool, sizeof(conn_t));
  c->pool = sub_pool;

  c->local_port = port;
  c->rfd = c->wfd = -1;

  if (bind_addr)
    addr_family = pr_netaddr_get_family(bind_addr);

  else if (inet_family)
    addr_family = inet_family;

  else {

    /* If no default family has been set, then default to IPv6 (if IPv6
     * support is enabled), otherwise use IPv4.
     */
#ifdef PR_USE_IPV6
    if (pr_netaddr_use_ipv6())
      addr_family = AF_INET6;

    else
      addr_family = AF_INET;
#else
    addr_family = AF_INET;
#endif /* PR_USE_IPV6 */
  }

  /* If fd == -1, there is no currently open socket, so create one.
   */
  if (fd == -1) {
    socklen_t salen;
    register unsigned int i = 0;

    /* Certain versions of Solaris apparently require us to be root
     * in order to create a socket inside a chroot.
     *
     * FreeBSD 2.2.6 (possibly other versions as well), has a security
     * "feature" which disallows SO_REUSEADDR from working if the socket
     * owners don't match.  The easiest thing to do is simply make sure
     * the socket is created as root.  (Note: this "feature" seems to apply
     * to _all_ BSDs.)
     */

#if defined(SOLARIS2) || defined(FREEBSD2) || defined(FREEBSD3) || \
    defined(FREEBSD4) || defined(FREEBSD5) || defined(FREEBSD6) || \
    defined(__OpenBSD__) || defined(__NetBSD__) || \
    defined(DARWIN6) || defined(DARWIN7) || defined(DARWIN8) || \
    defined(SCO3) || defined(CYGWIN) || defined(SYSV4_2MP) || \
    defined(SYSV5UNIXWARE7)
# ifdef SOLARIS2
    if (port != INPORT_ANY && port < 1024) {
# endif
      pr_signals_block();
      PRIVS_ROOT
# ifdef SOLARIS2
    }
# endif
#endif

    fd = socket(addr_family, SOCK_STREAM, tcp_proto);

#if defined(SOLARIS2) || defined(FREEBSD2) || defined(FREEBSD3) || \
    defined(FREEBSD4) || defined(FREEBSD5) || defined(FREEBSD6) || \
    defined(__OpenBSD__) || defined(__NetBSD__) || \
    defined(DARWIN6) || defined(DARWIN7) || defined(DARWIN8) || \
    defined(SCO3) || defined(CYGWIN) || defined(SYSV4_2MP) || \
    defined(SYSV5UNIXWARE7)
# ifdef SOLARIS2
    if (port != INPORT_ANY && port < 1024) {
# endif
      PRIVS_RELINQUISH
      pr_signals_unblock();
# ifdef SOLARIS2
    }
# endif
#endif

    if (fd == -1) {

      /* On failure, destroy the connection and return NULL. */
      inet_errno = errno;
      if (reporting)
        pr_log_pri(PR_LOG_ERR, "socket() failed in connection initialization: "
          "%s", strerror(inet_errno));
      destroy_pool(c->pool);
      return NULL;
    }

    /* Allow address reuse. */
    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (void *) &one,
        sizeof(one)) < 0)
      pr_log_pri(PR_LOG_NOTICE, "error setting SO_REUSEADDR: %s",
        strerror(errno));

    memset(&na, 0, sizeof(na));
    pr_netaddr_set_family(&na, addr_family);

    if (bind_addr)
      pr_netaddr_set_sockaddr(&na, pr_netaddr_get_sockaddr(bind_addr));

    else
      pr_netaddr_set_sockaddr_any(&na);

#if defined(PR_USE_IPV6) && defined(IPV6_V6ONLY)
    if (pr_netaddr_use_ipv6() &&
        addr_family == AF_INET6) {
      int on = 0;

# ifdef SOL_IP
      int level = SOL_IP;
# else
      int level = ipv6_proto;
# endif /* SOL_IP */

      /* If creating a wildcard socket IPv6 socket, make sure that it
       * will accept IPv4 connections as well.  This is the default on
       * Linux and Solaris; BSD usually defaults to allowing only IPv6
       * (depending on the net.inet6.ip6.v6only sysctl value).
       *
       * Ideally, this setsockopt() call would be configurable via the
       * SocketOptions directive.
       */

      if (setsockopt(fd, level, IPV6_V6ONLY, (void *) &on, sizeof(on)) < 0)
        pr_log_pri(PR_LOG_NOTICE, "error setting IPV6_V6ONLY: %s",
          strerror(errno));
    }
#endif /* PR_USE_IPV6 and IPV6_V6ONLY */

    pr_netaddr_set_port(&na, htons(port));

    if (port != INPORT_ANY && port < 1024) {
      pr_signals_block();
      PRIVS_ROOT
    }

    /* According to one expert, the very nature of the FTP protocol, and it's
     * multiple data-connections creates problems with "rapid-fire" connections
     * (transfering lots of files) causing an eventual "Address already in use"
     * error.  As a result, this nasty kludge retries ten times (once per
     * second) if the port being bound to is INPORT_ANY.
     */
    for (i = 10; i; i--) {
      res = bind(fd, pr_netaddr_get_sockaddr(&na),
        pr_netaddr_get_sockaddr_len(&na));
      hold_errno = errno;

      if (res == -1 && errno == EINTR) {
        pr_signals_handle();
	i++;
	continue;
      }

      if (res != -1 ||
          errno != EADDRINUSE ||
	  (port != INPORT_ANY && !retry_bind))
        break;

      if (port != INPORT_ANY && port < 1024) {
        PRIVS_RELINQUISH
        pr_signals_unblock();
      }

      pr_timer_sleep(1);

      if (port != INPORT_ANY && port < 1024) {
        pr_signals_block();
        PRIVS_ROOT
      }
    }

    if (res == -1) {
      if (port != INPORT_ANY && port < 1024) {
        PRIVS_RELINQUISH
        pr_signals_unblock();
      }

      if (reporting) {
        pr_log_pri(PR_LOG_ERR, "Failed binding to %s, port %d: %s",
          pr_netaddr_get_ipstr(&na), port, strerror(hold_errno));
        pr_log_pri(PR_LOG_ERR, "Check the ServerType directive to ensure "
          "you are configured correctly.");
      }

      inet_errno = hold_errno;
      destroy_pool(c->pool);
      close(fd);
      return NULL;
    }

    if (port != INPORT_ANY && port < 1024) {
      PRIVS_RELINQUISH
      pr_signals_unblock();
    }

    /* We use getsockname here because the caller might be binding to
     * INPORT_ANY (0), in which case our port number will be dynamic.
     */

    salen = pr_netaddr_get_sockaddr_len(&na);
    if (getsockname(fd, pr_netaddr_get_sockaddr(&na), &salen) != -1) {
      if (!c->local_addr)
        c->local_addr = pr_netaddr_alloc(c->pool);

      pr_netaddr_set_family(c->local_addr, pr_netaddr_get_family(&na));
      pr_netaddr_set_sockaddr(c->local_addr, pr_netaddr_get_sockaddr(&na));
      c->local_port = ntohs(pr_netaddr_get_port(&na));
    }
  }

  c->listen_fd = fd;
  register_cleanup(c->pool, (void *) c, conn_cleanup_cb, conn_cleanup_cb);

  return c;
}

conn_t *pr_inet_create_connection(pool *p, xaset_t *servers, int fd,
    pr_netaddr_t *bind_addr, int port, int retry_bind) {
  conn_t *c = NULL;

  c = inet_initialize_connection(p, servers, fd, bind_addr, port,
    retry_bind, TRUE);

  /* This code is somewhat of a kludge, because error handling should
   * NOT occur in inet.c, it should be handled by the caller.
   */

  if (!c)
    end_login(1);

  return c;
}

/* Attempt to create a connection bound to a given port range, returns NULL
 * if unable to bind to any port in the range.
 */
conn_t *pr_inet_create_connection_portrange(pool *p, xaset_t *servers,
    pr_netaddr_t *bind_addr, int low_port, int high_port) {
  int range_len, i;
  int *range, *ports;
  int attempt, random_index;
  conn_t *c = NULL;

  /* Make sure the temporary inet work pool exists. */
  if (!inet_pool) {
    inet_pool = make_sub_pool(permanent_pool); 
    pr_pool_tag(inet_pool, "Inet Pool");
  }

  range_len = high_port - low_port + 1;
  range = (int *) pcalloc(inet_pool, range_len * sizeof(int));
  ports = (int *) pcalloc(inet_pool, range_len * sizeof(int));

  i = range_len;
  while (i--)
    range[i] = low_port + i;

  for (attempt = 3; attempt > 0 && !c; attempt--) {
    for (i = range_len - 1; i >= 0 && !c; i--) {

      /* If this is the first attempt through the range, randomize
       * the order of the port numbers used.
       */

      if (attempt == 3) {
	/* Obtain a random index into the port array range. */
	random_index = (int) ((1.0 * i * rand()) / (RAND_MAX+1.0));

	/* Copy the port at that index into the array from which port
	 * numbers will be selected when calling
         * inet_initialize_connection().
	 */
	ports[i] = range[random_index];

	/* Move non-selected numbers down so that the next randomly chosen
	 * port will be from the range of as-yet untried ports.
	 */

	while (++random_index < i)
	  range[random_index-1] = range[random_index];
      }

      c = inet_initialize_connection(p, servers, -1, bind_addr, ports[i],
        FALSE, FALSE);

      if (!c && inet_errno != EADDRINUSE) {
        pr_log_pri(PR_LOG_ERR, "error initializing connection: %s",
          strerror(inet_errno));
        end_login(1);
      }
    }
  }

  return c;
}

void pr_inet_close(pool *p, conn_t *c) {

  /* It is not necessary to close the fds or schedule netio streams for
   * removal, because the creator of the connection (either
   * pr_inet_create_connection() or pr_inet_copy_connection() will have
   * registered a pool cleanup handler (conn_cleanup_cb()) which will do all
   * this for us. Simply destroy the pool and all the dirty work gets done.
   */

  destroy_pool(c->pool);
}

/* Perform shutdown/read on streams */
void pr_inet_lingering_close(pool *p, conn_t *c, long linger) {
  pr_inet_set_block(p, c);

  if (c->outstrm)
    pr_netio_lingering_close(c->outstrm, linger);

  /* Only close the input stream if it is actually a different stream than
   * the output stream.
   */
  if (c->instrm != c->outstrm)
    pr_netio_lingering_close(c->instrm, linger);

  c->outstrm = NULL;
  c->instrm = NULL;

  destroy_pool(c->pool);
}

/* Similar to a lingering close, perform a lingering abort. */
void pr_inet_lingering_abort(pool *p, conn_t *c, long linger) {
  pr_inet_set_block(p, c);

  if (c->instrm)
    pr_netio_lingering_abort(c->instrm, linger);

  /* Only close the output stream if it is actually a different stream
   * than the input stream.
   *
   * Note: we do not call pr_netio_lingering_abort() on the input stream
   * since doing so would result in two 426 responses sent; we only
   * want and need one.
   */
  if (c->outstrm != c->instrm)
    pr_netio_lingering_close(c->outstrm, linger);

  c->instrm = NULL;
  c->outstrm = NULL;

  destroy_pool(c->pool);
}

int pr_inet_set_proto_opts(pool *p, conn_t *c, int mss, int nodelay,
    int lowdelay, int throughput, int nopush) {
  int tos = 0;

  /* More portability fun.  Traditional BSD-style sockets want the value from
   * getprotobyname() in the setsockopt(2) call; Linux wants SOL_TCP for
   * these options.  Also, *BSD want IPPROTO_IP for IP_TOS options, Linux
   * wants SOL_IP.  How many other platforms will have variations?  Will
   * networking code always be this fragmented?
   */
#ifdef SOL_IP
  int ip_level = SOL_IP;
#else
  int ip_level = ip_proto;
#endif /* SOL_IP */

#ifdef SOL_TCP
  int tcp_level = SOL_TCP;
#else
  int tcp_level = tcp_proto;
#endif /* SOL_TCP */

  /* Some of these setsockopt() calls may fail when they operate on IPv6
   * sockets, rather than on IPv4 sockets.
   */

#ifdef TCP_NODELAY
  unsigned char *no_delay = get_param_ptr(main_server->conf, "tcpNoDelay",
    FALSE);

  if (!no_delay ||
      *no_delay == TRUE) {
    if (c->listen_fd != -1) {
      if (setsockopt(c->listen_fd, tcp_level, TCP_NODELAY, (void *) &nodelay,
          sizeof(nodelay)) < 0) {
        pr_log_pri(PR_LOG_NOTICE, "error setting listen fd TCP_NODELAY: %s",
          strerror(errno));
      }
    }
  }
#endif /* TCP_NODELAY */

#ifdef TCP_MAXSEG
  if (c->listen_fd != -1 &&
      mss) {
    if (setsockopt(c->listen_fd, tcp_level, TCP_MAXSEG, &mss,
        sizeof(mss)) < 0) {
      pr_log_pri(PR_LOG_NOTICE, "error setting listen fd TCP_MAXSEG(%d): %s",
        mss, strerror(errno));
    }
  }
#endif /* TCP_MAXSEG */

#ifdef IPTOS_LOWDELAY
  if (lowdelay)
    tos = IPTOS_LOWDELAY;
#endif /* IPTOS_LOWDELAY */

#ifdef IPTOS_THROUGHPUT
  if (throughput)
    tos = IPTOS_THROUGHPUT;
#endif /* IPTOS_THROUGHPUT */

#ifdef IP_TOS

  /* Only set TOS flags on IPv4 sockets; IPv6 sockets don't seem to support
   * them.
   */
  if (pr_netaddr_get_family(c->local_addr) == AF_INET) {
    if (c->listen_fd != -1) {
      if (setsockopt(c->listen_fd, ip_level, IP_TOS, (void *) &tos,
          sizeof(tos)) < 0) {
        pr_log_pri(PR_LOG_NOTICE, "error setting listen fd IP_TOS: %s",
          strerror(errno));
      }
    }
  }
#endif /* IP_TOS */

#ifdef TCP_NOPUSH
  /* NOTE: TCP_NOPUSH is a BSDism. */
  if (c->listen_fd != -1) {
    if (setsockopt(c->listen_fd, tcp_level, TCP_NOPUSH, (void *) &nopush,
        sizeof(nopush)) < 0) {
      pr_log_pri(PR_LOG_NOTICE, "error setting listen fd TCP_NOPUSH: %s",
        strerror(errno));
    }
  }
#endif /* TCP_NOPUSH */

  return 0;
}

/* Set socket options on a connection.  */
int pr_inet_set_socket_opts(pool *p, conn_t *c, int rcvbuf, int sndbuf) {

  /* Linux and "most" newer networking OSes probably use a highly adaptive
   * window size system, which generally wouldn't require user-space
   * modification at all.  Thus, check the current sndbuf and rcvbuf sizes
   * before changing them, and only change them if we are making them larger
   * than their current size.
   */

  if (c->listen_fd != -1) {
    int keepalive = 0;
    int crcvbuf, csndbuf;
    socklen_t len;

    if (setsockopt(c->listen_fd, SOL_SOCKET, SO_KEEPALIVE, (void *)
        &keepalive, sizeof(int)) < 0)
      pr_log_pri(PR_LOG_NOTICE, "error setting listen fd SO_KEEPALIVE: %s",
        strerror(errno));

    len = sizeof(csndbuf);
    getsockopt(c->listen_fd, SOL_SOCKET, SO_SNDBUF, (void *) &csndbuf, &len);

    if (sndbuf &&
        sndbuf > csndbuf) {
      if (setsockopt(c->listen_fd, SOL_SOCKET, SO_SNDBUF, (void *) &sndbuf,
          sizeof(sndbuf)) < 0)
        pr_log_pri(PR_LOG_NOTICE, "error setting listen fd SO_SNDBUF: %s",
          strerror(errno));
    }

    c->sndbuf = (sndbuf ? sndbuf : csndbuf);

    len = sizeof(crcvbuf);
    getsockopt(c->listen_fd, SOL_SOCKET, SO_RCVBUF, (void *) &crcvbuf, &len);

    if (rcvbuf &&
        rcvbuf > crcvbuf) {
      if (setsockopt(c->listen_fd, SOL_SOCKET, SO_RCVBUF, (void *) &rcvbuf,
          sizeof(rcvbuf)) < 0)
        pr_log_pri(PR_LOG_NOTICE, "error setting listen fd SO_RCVFBUF: %s",
          strerror(errno));
    }

    c->rcvbuf = (rcvbuf ? rcvbuf : crcvbuf);
  }

  return 0;
}

#ifdef SO_OOBINLINE
static void set_oobinline(int fd) {
  int on = 1;
  if (fd != -1)
    if (setsockopt(fd, SOL_SOCKET, SO_OOBINLINE, (void*)&on, sizeof(on)) < 0)
      pr_log_pri(PR_LOG_NOTICE, "error setting SO_OOBINLINE: %s",
        strerror(errno));
}
#endif

#ifdef F_SETOWN
static void set_owner(int fd) {
  if (fd != -1)
    fcntl(fd, F_SETOWN, getpid());
}
#endif

/* Put a socket in async mode (so SIGURG is raised on OOB)
 */
int pr_inet_set_async(pool *p, conn_t *c) {

#ifdef SO_OOBINLINE
  set_oobinline(c->listen_fd);
  set_oobinline(c->rfd);
  set_oobinline(c->wfd);
#endif

#ifdef F_SETOWN
  set_owner(c->listen_fd);
  set_owner(c->rfd);
  set_owner(c->wfd);
#endif

  return 0;
}

/* Put a socket in nonblocking mode.
 */
int pr_inet_set_nonblock(pool *p, conn_t *c) {
  int flags;
  int res = -1;

  errno = EBADF;		/* Default */

  if (c->mode == CM_LISTEN) {
    flags = fcntl(c->listen_fd, F_GETFL);
    res = fcntl(c->listen_fd, F_SETFL, flags|O_NONBLOCK);

  } else {
    if (c->rfd != -1) {
      flags = fcntl(c->rfd, F_GETFL);
      res = fcntl(c->rfd, F_SETFL, flags|O_NONBLOCK);
    }

    if (c->wfd != -1) {
      flags = fcntl(c->wfd, F_GETFL);
      res = fcntl(c->wfd, F_SETFL, flags|O_NONBLOCK);
    }
  }

  return res;
}

int pr_inet_set_block(pool *p, conn_t *c) {
  int flags;
  int res = -1;

  errno = EBADF;		/* Default */

  if (c->mode == CM_LISTEN) {
    flags = fcntl(c->listen_fd, F_GETFL);
    res = fcntl(c->listen_fd, F_SETFL, flags & (U32BITS ^ O_NONBLOCK));

  } else {
    if (c->rfd != -1) {
      flags = fcntl(c->rfd, F_GETFL);
      res = fcntl(c->rfd, F_SETFL, flags & (U32BITS ^ O_NONBLOCK));
    }

    if (c->wfd != -1) {
      flags = fcntl(c->wfd, F_GETFL);
      res = fcntl(c->wfd, F_SETFL, flags & (U32BITS ^ O_NONBLOCK));
    }
  }

  return res;
}

/* Put a connection in listen mode
 */
int pr_inet_listen(pool *p, conn_t *c, int backlog) {
  if (!c || c->mode == CM_LISTEN)
    return -1;

  while (TRUE)
    if (listen(c->listen_fd, backlog) == -1) {
      if (errno == EINTR) {
        pr_signals_handle();
        continue;
      }

      pr_log_pri(PR_LOG_ERR, "unable to listen on %s#%u: %s",
        pr_netaddr_get_ipstr(c->local_addr), c->local_port, strerror(errno));
      end_login(1);

    } else
      break;

  c->mode = CM_LISTEN;
  return 0;
}

/* Reset a connection back to listen mode.  Enables blocking mode
 * for safety.
 */
int pr_inet_resetlisten(pool *p, conn_t *c) {
  c->mode = CM_LISTEN;
  pr_inet_set_block(c->pool, c);
  return 0;
}

int pr_inet_connect(pool *p, conn_t *c, pr_netaddr_t *addr, int port) {
  pr_netaddr_t remote_na;
  int res = 0;

  pr_inet_set_block(p, c);

  /* No need to initialize the remote_na netaddr here, as we're directly
   * copying the data from the given netaddr into that memory area.
   */

  memcpy(&remote_na, addr, sizeof(remote_na));
  pr_netaddr_set_port(&remote_na, htons(port));

  c->mode = CM_CONNECT;

  while (TRUE) {
    if ((res = connect(c->listen_fd, pr_netaddr_get_sockaddr(&remote_na),
        pr_netaddr_get_sockaddr_len(&remote_na))) == -1 && errno == EINTR) {
      pr_signals_handle();
      continue;

    } else
      break;
  }

  if (res == -1) {
    c->mode = CM_ERROR;
    c->xerrno = errno;
    return -1;
  }

  c->mode = CM_OPEN;

  if (pr_inet_get_conn_info(c, c->listen_fd) < 0) {
    c->xerrno = errno;
    return -1;
  }

  pr_inet_set_block(c->pool, c);
  return 1;
}

/* Attempt to connect a connection, returning immediately with 1 if connected,
 * 0 if not connected, or -1 if error.  Only needs to be called once, and can
 * then be selected for writing.
 */
int pr_inet_connect_nowait(pool *p, conn_t *c, pr_netaddr_t *addr, int port) {
  pr_netaddr_t remote_na;

  pr_inet_set_nonblock(p, c);

  /* No need to initialize the remote_na netaddr here, as we're directly
   * copying the data from the given netaddr into that memory area.
   */

  memcpy(&remote_na, addr, sizeof(remote_na));
  pr_netaddr_set_port(&remote_na, htons(port));

  c->mode = CM_CONNECT;
  if (connect(c->listen_fd, pr_netaddr_get_sockaddr(&remote_na),
      pr_netaddr_get_sockaddr_len(&remote_na)) == -1) {
    if (errno != EINPROGRESS && errno != EALREADY) {
      c->mode = CM_ERROR;
      c->xerrno = errno;
      return -1;
    }

    return 0;
  }

  c->mode = CM_OPEN;

  if (pr_inet_get_conn_info(c, c->listen_fd) < 0) {
    c->xerrno = errno;
    return -1;
  }

  pr_inet_set_block(c->pool, c);
  return 1;
}

/* Accepts a new connection, returning immediately with -1 if no connection is
 * available.  If a connection is accepted, creating a new conn_t and potential
 * resolving is deferred, and a normal socket fd is returned for the new
 * connection, which can later be used in pr_inet_openrw() to fully open and
 * resolve addresses.
 */
int pr_inet_accept_nowait(pool *p, conn_t *c) {
  int fd;

  if (c->mode == CM_LISTEN)
    pr_inet_set_nonblock(c->pool, c);

  /* A directive could enforce only IPv4 or IPv6 connections here, by
   * actually using a sockaddr argument to accept(2), and checking the
   * family of the connecting entity.
   */

  c->mode = CM_ACCEPT;
  while (TRUE) {
    pr_signals_handle();
    fd = accept(c->listen_fd, NULL, NULL);

    if (fd == -1) {
      if (errno == EINTR)
        continue;

      if (errno != EWOULDBLOCK) {
        c->mode = CM_ERROR;
        c->xerrno = errno;
        return -1;
      }

      c->mode = CM_LISTEN;
      c->xerrno = 0;
      return -1;
    }

    break;
  }

  /* Leave the connection in CM_ACCEPT mode, so others can see
   * our state.  Re-enable blocking mode, however.
   */
  pr_inet_set_block(c->pool, c);

  return fd;
}

/* Accepts a new connection, cloning the existing conn_t and returning
 * it, or NULL upon error.
 */
conn_t *pr_inet_accept(pool *p, conn_t *d, conn_t *c, int rfd, int wfd,
    unsigned char resolve) {
  conn_t *res = NULL;
  unsigned char *allow_foreign_addr = NULL;
  int fd = -1;

  pr_netaddr_t na;
  socklen_t nalen;

  /* Initialize the netaddr. */
  pr_netaddr_clear(&na);

  pr_netaddr_set_family(&na, pr_netaddr_get_family(c->remote_addr));
  nalen = pr_netaddr_get_sockaddr_len(&na);

  d->mode = CM_ACCEPT;

  allow_foreign_addr = get_param_ptr(TOPLEVEL_CONF,
    "AllowForeignAddress", FALSE);

  /* A directive could enforce only IPv4 or IPv6 connections here, by
   * actually using a sockaddr argument to accept(2), and checking the
   * family of the connecting entity.
   */

  while (TRUE) {
    pr_signals_handle();

    fd = accept(d->listen_fd, pr_netaddr_get_sockaddr(&na), &nalen);
    if (fd != -1) {
      if ((!allow_foreign_addr || *allow_foreign_addr == FALSE) &&
          (getpeername(fd, pr_netaddr_get_sockaddr(&na), &nalen) != -1)) {

        if (pr_netaddr_cmp(&na, c->remote_addr) != 0) {
          pr_log_pri(PR_LOG_NOTICE,
            "SECURITY VIOLATION: Passive connection from %s rejected.",
            pr_netaddr_get_ipstr(&na));
          close(fd);
          continue;
        }
      }

      d->mode = CM_OPEN;
      res = pr_inet_openrw(p, d, NULL, PR_NETIO_STRM_DATA, fd, rfd, wfd,
        resolve);

    } else {
      if (errno == EINTR)
        continue;

      d->mode = CM_ERROR;
      d->xerrno = errno;
    }

    break;
  }

  return res;
}

int pr_inet_get_conn_info(conn_t *c, int fd) {
  pr_netaddr_t na;
  socklen_t nalen;

  /* Sanity check. */
  if (fd < 0) {
    errno = EBADF;
    return -1;
  }

  /* Initialize the netaddr. */
  pr_netaddr_clear(&na);

#ifdef PR_USE_IPV6
  if (pr_netaddr_use_ipv6())
    pr_netaddr_set_family(&na, AF_INET6);

  else
    pr_netaddr_set_family(&na, AF_INET);
#else
  pr_netaddr_set_family(&na, AF_INET);
#endif /* PR_USE_IPV6 */
  nalen = pr_netaddr_get_sockaddr_len(&na);

  if (getsockname(fd, pr_netaddr_get_sockaddr(&na), &nalen) != -1) {
    if (!c->local_addr)
      c->local_addr = pr_netaddr_alloc(c->pool);

    /* getsockname(2) will read the local socket information into the struct
     * sockaddr * given.  Which means that the address family of the local
     * socket can be found in struct sockaddr *->sa_family, and not (yet)
     * via pr_netaddr_get_family().
     */
    pr_netaddr_set_family(c->local_addr,
      pr_netaddr_get_sockaddr(&na)->sa_family);
    pr_netaddr_set_sockaddr(c->local_addr, pr_netaddr_get_sockaddr(&na));
    c->local_port = ntohs(pr_netaddr_get_port(&na));

  } else
    return -1;

  /* "Reset" the pr_netaddr_t struct for the getpeername(2) call. */
#ifdef PR_USE_IPV6
  if (pr_netaddr_use_ipv6())
    pr_netaddr_set_family(&na, AF_INET6);

  else
    pr_netaddr_set_family(&na, AF_INET);
#else
  pr_netaddr_set_family(&na, AF_INET);
#endif /* PR_USE_IPV6 */
  nalen = pr_netaddr_get_sockaddr_len(&na);

  if (getpeername(fd, pr_netaddr_get_sockaddr(&na), &nalen) != -1) {
    c->remote_addr = pr_netaddr_alloc(c->pool);

    pr_netaddr_set_family(c->remote_addr,
      pr_netaddr_get_sockaddr(&na)->sa_family);
    pr_netaddr_set_sockaddr(c->remote_addr, pr_netaddr_get_sockaddr(&na));
    c->remote_port = ntohs(pr_netaddr_get_port(&na));

  } else
    return -1;

  return 0;
}

/* Associate already open streams with the connection, returns NULL if either
 * stream points to a non-socket descriptor.  If addr is non-NULL, remote
 * address discovery is attempted. If resolve is non-zero, the remote address
 * is reverse resolved.
 */
conn_t *pr_inet_associate(pool *p, conn_t *c, pr_netaddr_t *addr,
    pr_netio_stream_t *in, pr_netio_stream_t *out, int resolve) {
  int rfd, wfd;
  int socktype;
  socklen_t socktype_len = sizeof(socktype);
  conn_t *res;

  rfd = PR_NETIO_FD(in);
  wfd = PR_NETIO_FD(out);

  if (getsockopt(rfd, SOL_SOCKET, SO_TYPE, (void *) &socktype,
      &socktype_len) == -1 || socktype != SOCK_STREAM)
    return NULL;

  if (getsockopt(wfd, SOL_SOCKET, SO_TYPE, (void *) &socktype,
      &socktype_len) == -1 || socktype != SOCK_STREAM)
    return NULL;

  res = pr_inet_copy_connection(p, c);

  res->rfd = rfd;
  res->wfd = wfd;
  res->instrm = in;
  res->outstrm = out;
  res->mode = CM_OPEN;

  if (pr_inet_get_conn_info(res, wfd) < 0)
    return NULL;

  /* Get the remote address */

  if (addr) {
    if (!res->remote_addr)
      res->remote_addr = pr_netaddr_alloc(res->pool);

    memcpy(res->remote_addr, addr, sizeof(pr_netaddr_t));
  }

  if (resolve && res->remote_addr)
    res->remote_name = pr_netaddr_get_dnsstr(res->remote_addr);

  if (!res->remote_name)
    res->remote_name = pr_netaddr_get_ipstr(res->remote_addr);

  pr_inet_set_socket_opts(res->pool, res, 0, 0);
  return res;
}

/* Open streams for a new socket. If rfd and wfd != -1, two new fds are duped
 * to the respective read/write fds. If the fds specified correspond to the
 * normal stdin and stdout, the streams opened will be assigned to stdin and
 * stdout in an intuitive fashion (so that they may be later be used by
 * printf/fgets type libc functions).  If inaddr is non-NULL, the address is
 * assigned to the connection (as the *source* of the connection).  If it is
 * NULL, remote address discovery will be attempted.  The connection structure
 * appropriate fields are filled in, including the *destination* address.
 * Finally, if resolve is non-zero, this function will attempt to reverse
 * resolve the remote address.  A new connection structure is created in the
 * specified pool.
 *
 * Important, do not call any log_* functions from inside of pr_inet_openrw()
 * or any functions it calls, as the possibility for fd overwriting occurs.
 */
conn_t *pr_inet_openrw(pool *p, conn_t *c, pr_netaddr_t *addr, int strm_type,
    int fd, int rfd, int wfd, int resolve) {
  conn_t *res = NULL;
  int close_fd = TRUE;

  res = pr_inet_copy_connection(p, c);

  res->listen_fd = -1;

  /* Note: there are some cases where the given file descriptor will
   * intentionally be bad (e.g. in get_ident() lookups).  In this case,
   * errno will have a value of EBADF; this is an "acceptable" error.  Any
   * other errno value constitutes an unacceptable error.
   */
  if (pr_inet_get_conn_info(res, fd) < 0 && errno != EBADF)
    return NULL;

  if (addr) {
    if (!res->remote_addr)
      res->remote_addr = pr_netaddr_alloc(res->pool);

    memcpy(res->remote_addr, addr, sizeof(pr_netaddr_t));
  }

  if (resolve && res->remote_addr)
    res->remote_name = pr_netaddr_get_dnsstr(res->remote_addr);

  if (!res->remote_name)
    res->remote_name = pr_netaddr_get_ipstr(res->remote_addr);

  if (fd == -1 && c->listen_fd != -1)
    fd = c->listen_fd;

  if (rfd != -1) {
    if (fd != rfd)
      dup2(fd, rfd);
    else
      close_fd = FALSE;

  } else
    rfd = dup(fd);

  if (wfd != -1) {
    if (fd != wfd) {
      if (wfd == STDOUT_FILENO)
        fflush(stdout);
      dup2(fd, wfd);

    } else
      close_fd = FALSE;

  } else
    wfd = dup(fd);

  /* Now discard the original socket */
  if (rfd != -1 && wfd != -1 && close_fd)
    close(fd);

  res->rfd = rfd;
  res->wfd = wfd;

  res->instrm = pr_netio_open(res->pool, strm_type, res->rfd, PR_NETIO_IO_RD);
  res->outstrm = pr_netio_open(res->pool, strm_type, res->wfd, PR_NETIO_IO_WR);

  /* Set options on the sockets. */
  pr_inet_set_socket_opts(res->pool, res, 0, 0);
  pr_inet_set_block(res->pool, res);

  res->mode = CM_OPEN;

#if defined(HAVE_STROPTS_H) && defined(I_SRDOPT) && defined(RPROTDIS) && \
    defined(SOLARIS2)
  /* This is needed to work around control messages in STREAMS devices
   * (as on Solaris 9/NFS).
   */
  while (ioctl(res->rfd, I_SRDOPT, RPROTDIS) < 0) {
    if (errno == EINTR) {
      pr_signals_handle();
      continue;
    }

    pr_log_pri(PR_LOG_WARNING, "error calling ioctl(RPROTDIS): %s", 
      strerror(errno));
    break;
  }
#endif

  return res;
}

void init_inet(void) {
  struct protoent *pr = NULL;

#ifdef HAVE_SETPROTOENT
  setprotoent(FALSE);
#endif

  pr = getprotobyname("ip"); 
  if (pr != NULL)
    ip_proto = pr->p_proto;

#ifdef PR_USE_IPV6
  pr = getprotobyname("ipv6"); 
  if (pr != NULL)
    ipv6_proto = pr->p_proto;
#endif /* PR_USE_IPV6 */

  pr = getprotobyname("tcp");
  if (pr != NULL)
    tcp_proto = pr->p_proto;

#ifdef HAVE_ENDPROTOENT
  endprotoent();
#endif

  if (inet_pool)
    destroy_pool(inet_pool);
  inet_pool = make_sub_pool(permanent_pool);
  pr_pool_tag(inet_pool, "Inet Pool");
}
