#define VERSION "2.6"
#define TRG "fakeidentd"

#if 0 /* -*-  mode: c; c-file-style: "gnu"; tab-width: 8; -*-

#   This program is easy to compile. For example the following ways:
#       $ sh identd.c
#       $ sh identd.c -g -DDEBUG
#       $ sh identd.c -s -DXXXMULTI
#       $ sh identd.c TRG=fake_identd -s -DBIND_ADDRESS=127.0.0.1
#       $ sh identd.c CC=cc
#       $ sh identd.c CC=egcs -s -fomit-frame-pointer

set -eu

CC= TRG=`basename "$0" .c` OIFS=$IFS
for arg in "$@" ''
do case $arg in	TRG=*) TRG=`echo "$arg" | sed 's/TRG=//'`; shift ;;
		CC=*) CC=`echo "$arg" | sed 's/CC=//'`; shift ;;
		clean) set -x; exec rm -f "$TRG" ;;
		readme) set -x; exec sed -n '1,/[e]nd/d;/\*\//q;s/..//p' "$0";;
		'') set 0 -s -O2; shift; break ;;
		*) break ;;
esac; done
case `uname` in SunOS) L='-lsocket -lnsl' ;; *) L= ;; esac

WARN="-Wall -Wstrict-prototypes -pedantic -Wno-long-long"
WARN="$WARN -Wcast-align -Wpointer-arith " # -Wfloat-equal #-Werror
WARN="$WARN -W -Wwrite-strings -Wcast-qual -Wshadow" # -Wconversion

VERSION=`sed -n '/^ [*] Version / {
	s/.*Version \([^ ]*\)  *\([^ ]*\).*./\1 (\2)/p; q; }' "$0"`
case $VERSION in '') echo Could not read version information. >&2; exit 1; esac
TRGNAME=`basename "$TRG"`
set -x; exec ${CC:-gcc} $WARN "$@" -DTRG="\"$TRGNAME\"" \
	-DVERSION="\"$VERSION\"" -o "$TRG" "$0" $L
exit 1
# */
#endif
/*
 * identd.c 2.6  2012-05-31 20:37:27 UTC
 *
 * Author: Tomi Ollila -- too ät iki fi
 *
 * Created: Sat Nov 25 15:34:07 EET 1995 too
 * Last modified: Thu 31 May 2012 23:37:27 EEST too
 *
 * This program is standalone 'fake' ident daemon. This program does
 * not fork() but is configured to handle up to 20 concurrent connections.
 * Since one connection should not last long, if all 20 connections are
 * in use, the next connection will close the oldest connection data
 * has been read. This way this program is not very vulnerable to so
 * called `denial of service' attack, thus making this ideal "identd"
 * to be used in a firewall, IP masquerading hosts etc.
 *
 * Program takes one (or many) arguments, which if exist, determines the
 * `user' name(s) that is returned for successful ident query.
 *
 * 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, 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.
 *
 * HISTORY
 *
 * Version 2.6  2012-05-31 20:37:27 UTC
 *   Applied patches from the wl500g project, including IPv6 support, with
 *   minor tweaks (patches provided by Daniel Gimpelevich. Thanks).
 *
 * Version 2.5  $Id: identd.c 862 2006-05-18 14:16:34Z too $
 *   Minor build and readme updates.
 *
 * Version 2.4  identd.c 568 2005-09-07 20:18:39Z too
 *   More compilation warnings options set -- iov.base being non-const
 *   gives warnings that are hard to avoid...
 *
 * Version 2.3  identd.c 564 2005-09-06 19:15:20Z too
 *   Randident code from  Matthias Jung  tuned in.
 *
 * Version 2.2  identd.c 12 2004-09-08 21:46:54Z too
 *   Fixed getservbyname() to look port for "auth" instead of "identd"
 *   port. This "bug" also revealed port number byte order handling bug,
 *   which was fixed.
 *   Now this file is stored in subversion repository -- I entered
 *   $ svn propset svn:keywords Id identd.c -- let's see how it works...
 *   ... ``svn propset svn:keywords 'Id Rev' identd.c'' !!!
 *
 * Revision 2.1  2004/01/15 18:14:42  too
 *   Made BIND_ADDRESS definable (in compiler command line).
 *   Added some typecasts (using checked_cast() macro).
 *   Thanks to Jeffrey D. Wheelhouse for his content.
 *
 * Revision 2.0  2003/05/05 15:21:01  too
 *   Major update. Removed fdprintf(); replaced with use of
 *   writev() and newly added outputstrings().
 *   Removed many now obsolete defines and converted one to
 *   constant character string.
 *   Added one assert() (and left room for more). Did some
 *   relativily small other adjustments.
 *
 * Revision 1.7  2002/09/29 07:50:20  too
 *   No longer chops up to IDSTR_MAX chars, but uses "%.*s" to limit length;
 *   now works also when XXXMULTI defined.
 *   Back-hacked self-compilable trick, with more tricks to avoid compiler
 *   warnings.
 *   Removed own define of FD_SETSIZE altogether;
 *   systems has it small to begin with.
 *   Line '415' (or whatever that is now) fixed. () -> (void) in func def.
 *   Some fine-tuning.
 *   Thanks to Cristian for his patches.
 *
 * Revision 1.6.1  2002-09-28 12:30:29 +0200  cii
 *   + added defines for IDSTR_MAX, IDENT_SUBSTR, IDSTR_BUFLEN and IDSTR_MAX
 *     (length limit on the id-string)
 *   + program arg 1 chopped after IDSTR_MAX characters (when applicable);
 *     reason is:
 *       - if the program is called with a relativelly long string as arg 1
 *         (tested with about 400 chars), a segfault occurs due to an internal
 *         buffer overflow (buffer space reserved for id-string is 128 chars,
 *         but never verified)
 *       - it may trigger buffer overflows in clients
 *   + put a proper comment at the top of the file
 *   + sorted out FD_SETSIZE (on Linux it's already defined)
 *       - moved it down below all the includes
 *   + added time.h include
 *   + added some short comments
 *   + conditionals '{', '}' enclosed
 *   + variable index -> idx in function closeOldest (killed a warning)
 *   + splitted multiple statements on a singel line
 *   + splitted long lines
 *   + prototypes ending in '()' -> '(void)'; changed by protoize
 *   + corrected most warnings, but "function declaration isn't a prototype"
 *     which still occurs on line: 415
 *   + added IDENT_PORT
 *   + added IDENT_SUBSTR
 *
 * Revision 1.6  2002/07/31 16:25:20  too
 *   Now works when started as root (in Linux). Stupid me, tested
 *   only starting as an ordinary loser.
 *
 * Revision 1.5  2002/07/29 14:02:42  too
 *   Added possibility to have multible reply users, one (pseudo)randomly
 *   chosen at each time.
 *
 * Revision 1.4  2001/02/09 08:45:42  too
 *   Now GID is also changed to nobody/nogroup.
 *
 * Revision 1.3  2000/06/07 05:55:44  too
 *   Fixed some Solaris compilation "bugs".
 *   Changed LOG_PERROR to LOG_CONS
 *
 * Revision 1.2  1999/07/30 04:08:42  too
 *   Added printing version string (and exit) with `-V' command line option.
 *
 * Revision 1.1  1999/04/21 17:23:20  too
 * - Writes process id to /var/run/identd.pid.
 * - Changes (effective) user id to `nobody' after initialization
 *      (binding socket etc.).
 * - Ignores some signals (HUP and PIPE).
 * - Handles some signals that aborts by default. The handler function
 *      tries to get rid of the pidfile.
 *
 * Revision 0.9b 1999/04/15 20:45:12  too
 *   Not so much spaghetti anymore. Added documentation and more replies.
 *
 * Revision 0.9  1999/04/12 18:30:00  too
 *   Version for unix systems. Standalone, supports 20 concurrent connections.
 *   The code is quite a spaghetti. But that does not matter.
 */

#ifdef DEBUG
#undef ndebug
#else
#define ndebug 1
#endif

#include <assert.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <fcntl.h>
#include <signal.h>
#include <syslog.h>

#include <pwd.h>
#include <netdb.h>

#include <sys/syslog.h>
#include <sys/types.h>
#include <sys/time.h>
#include <time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <arpa/inet.h>
#include <sys/uio.h>

#include <endian.h>

#if __BYTE_ORDER == __BIG_ENDIAN

#define IPADDR(a,b,c,d) ((in_addr_t)((a << 24) + (b << 16) + (c << 8) + d))
#define IPPORT(v) ((in_port_t)v)
#define A_x_256(a)((a<<8))

#elif __BYTE_ORDER == __LITTLE_ENDIAN

#define IPADDR(a,b,c,d) (a + (b << 8) + (c << 16) + (d << 24))
#define IPPORT(v) ((in_port_t)((v >> 8) | (v << 8)))
#define A_x_256(a) (a)

#else
#error unknown ENDIAN
#endif

#ifndef __STRING
#define __STRING(x) #x
#endif
/* Let's see how long-lived this is... */
#define __STRINGIFY_MACRO(x) __STRING(x)

#ifndef BIND_ADDRESS
#define BIND_ADDRESS	0.0.0.0
#endif
#ifndef BIND_ADDRESS6
#define BIND_ADDRESS6	::
#endif
#define IDENT_PORT	113
#define MAXCONNS	20
#define MAXIDLETIME	45

#ifndef USE_UNIX_OS
static const char ident_substr[] = " : USERID : OTHER : ";
#else
static const char ident_substr[] = " : USERID : UNIX : ";
#endif
static const int ident_substr_len = sizeof ident_substr - 1;

#if !defined __cplusplus
typedef enum { false = 0, true = 1 } bool;
#endif

#if (__GNUC__ >= 3)
#define GCCATTR_UNUSED	 __attribute ((unused))

#define from_type(ft, v) \
  __builtin_choose_expr (__builtin_types_compatible_p (typeof (v), ft), \
			 (v), (void)0)

#define checked_cast(ft, tt, v) \
  __builtin_choose_expr (__builtin_types_compatible_p (typeof (v), ft), \
			 ((tt)(v)), (void)0)
#else
#define GCCATTR_UNUSED

#define from_type(ft, v) (v)
#define checked_cast(ft, tt, v) ((tt)(v))
#endif

/* ... */
#define CVP (const void *)

#ifndef DEBUG
#define FCS		2	/* First Connection Socket */
#define TRACE(x, y);
#else
#define FCS		4
#define TRACE(x, y)	if (x) printf y
#endif

/* descriptors when debugging:
 *  0 = server socket
 *  1 = standard output (debugging output)
 *  2 = standard error
 *  3 = syslog fd (hopefully -- otherwise may work a bit wierdly)
 *  4 - 4 + MAXCONNS = connection sockets
 *
 * descriptors when not debugging
 *  0 = server socket
 *  1 = syslog fd (hopefully -- otherwise this won't work)
 *  2 = connection socket after detached from tty. standard error before that
 *  3 - 2 + MAXCONNS = rest connection sockets
 *
 * To try to make sure that syslog fd is what is "requested", the that fd
 * is closed before openlog() call. It can only severely fail if fd 0
 * is initially closed.
 */

/*
 * FD of the connection is always the index of the connection structure
 * in `conns' array + FCS
 */
struct {
  char		buf[20];
  int		len;
  time_t	lasttime;
} conns[MAXCONNS];


/*
 * To support multible usernames that can be replied by this fake identd
 * define `XXXMULTI' in compilation command line. This doesn't look guite
 * pretty, but alternatives looks even uglier.
 * XXX NOTE: multi currently only slightly tested XXXX.
 */
#ifdef XXXMULTI
#define IU_IN_STRUCT const char * const * identuserlist; int identusers
#define SET_IU(s, c) do { G.identuserlist = &(s); G.identusers = c; } while (0)
#define IU_IN_USAGESTR "[identuser [identuser2...]]"
#else
#define IU_IN_STRUCT const char * identuser
#define SET_IU(s, c) G.identuser = (s)
#define IU_IN_USAGESTR "[identuser]"
#endif

/* When using global variables, bind those at least to a structure. */
struct {
  IU_IN_STRUCT;
  fd_set	readfds;
  int		conncnt;
  bool		randident;
} G;

/*
 * Prototypes
 */
static void reply(int s, char * buf);
static void replyError(int s, const char * buf);
static const char * strerrno(void);

static const int one = 1;
static const char * const nobodystr = "nobody";
static const char * alphanum =
  "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

static inline void movefd(int from, int to)
{
  TRACE(1, ("movefd(from = %d, to = %d)\n", from, to));
  if (from != to)
    {
      dup2(from, to);
      close(from);
    }
}

/*
 * inetbind() must always return 0 or value < 0.
 * ... i.e. this version -- saves need for storage of the return value.
 */

#if 0 /* unused */
static int inetbind(int port)
{
  return inetbind(htons(port));
}
#endif

static int inetbind(int ipport)
{
  int s, len;
  union {
    struct sockaddr_in	sin4;
    struct sockaddr_in6 sin6;
  } addr;

  close(0);
  memset(&addr, 0, sizeof addr);

  if ((s = socket(AF_INET6, SOCK_STREAM, 0)) >= 0)
    {
      len = sizeof addr.sin6;
      inet_pton(AF_INET6, __STRINGIFY_MACRO(BIND_ADDRESS6), &addr.sin6.sin6_addr);
      addr.sin6.sin6_family = AF_INET6;
      addr.sin6.sin6_port = ipport;
    }
  else
  if ((s = socket(AF_INET, SOCK_STREAM, 0)) >= 0)
    {
      len = sizeof addr.sin4;
      addr.sin4.sin_addr.s_addr = inet_addr(__STRINGIFY_MACRO(BIND_ADDRESS));
      addr.sin4.sin_family = AF_INET;
      addr.sin4.sin_port = ipport;
    }
  else
    {
      syslog(LOG_CRIT, "Can not create server socket: %s.", strerrno());
      return -1;
    }

  setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one);

  if (bind(s, (struct sockaddr *)&addr, len) < 0)
    {
      syslog(LOG_CRIT, "Can not bind() server socket: %s.", strerrno());
      return -1;
    }

  if (listen(s, 5) < 0)
    {
      syslog(LOG_CRIT, "Can not listen() server socket: %s.", strerrno());
      return -1;
    }

  movefd(s, 0);

  return 0;
}

static void deleteConn(int s)
{
  int i = s - FCS;

  TRACE(1, ("deleteConn(): socket %d, conncnt %d\n", s, G.conncnt));

  close(s);

  G.conncnt--;

  /*
   * Most of the time there is 0 connections. Most often that there
   * is connections, there is just one connection. When this one connection
   * closes, i == G.conncnt = 0 -> no copying.
   * When there is more than one connection, the oldest connections closes
   * earlier on average. When this happens, the code below starts copying
   * the connection structure w/ highest index to the place which which is
   * just deleted. This means that the connection structures are no longer
   * in chronological order. I'd quess this means that when there is more
   * than 1 connection, on average every other connection structure needs
   * to be copied over the time all these connections are deleted.
   */
  if (i != G.conncnt)
    {
      memcpy(&conns[i], &conns[G.conncnt], sizeof conns[0]);
      movefd(G.conncnt + FCS, s);
    }

  TRACE(1, ("Clearing fd %d, readfds now 0x%x\n\n",
	    G.conncnt + FCS, *(int *)&G.readfds));

  FD_CLR(G.conncnt + FCS, &G.readfds);
}

static int closeOldest(void)
{
  time_t min = conns[0].lasttime;
  int	 idx = 0;
  int	 i;

  for (i = 1; i < MAXCONNS; i++)
    if (conns[i].lasttime < min)
      idx = i;

  TRACE(1, ("closeOldest(): index %d, socket %d\n", idx, idx + FCS));

  replyError(idx + FCS, "X-SERVER-TOO-BUSY");
  close(idx + FCS);

  return idx;
}


static int checkInput(char * buf, int len, int l)
{
  int	i;

  for (i = len; i < len + l; i++)
    if (buf[i] == '\n')
      return 1;

  return 0;
}


static int getport(void)
{
  struct servent * se;

  if ((se = getservbyname("auth", "tcp")) == NULL)
    return IPPORT(IDENT_PORT);
  else
    return se->s_port;
}

static const char * strerrno()
{
#if 1
  return strerror(errno);
#else
  extern char * sys_errlist[];
  return sys_errlist[errno];
#endif
}

#define WriteCS(f, s) write(f, s, sizeof s - 1)

static void writestrings(int fd, const char * str, ...)
{
  va_list ap;

  va_start(ap, str);

  while (str)
    {
      write(fd, str, strlen(str));
      str = va_arg(ap, const char *);
    }
  va_end(ap);
}

#ifndef DEBUG
static void godaemon(void)
{
  switch(fork())
    {
    case -1:	exit(-1);
    case 0:	close(1); close(2); setsid();  break;
    default:	exit(0);
    }
}
#endif

#ifdef TRG
#define PIDFILE "/var/run/" TRG ".pid"
#else
#define PIDFILE "/var/run/identd.pid"
#endif

static void delpidfile(void)
{
  /*
   * Usually nobody has no write/delete access to directory /var/run/
   * therefore if file cannot be deleted, it is truncated
   */
  if (unlink(PIDFILE) < 0)
    close(open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0644));
}

static void handlexitsigs(void)
{
  delpidfile();
  exit(0);
}

static void writepid(uid_t nobody, uid_t nogrp)
     /* May succeed. If not, won't care. */
{
  int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
  char buf[24];

  if (fd < 0)
    return;

  /* we don't use snprintf() here since it is not so portable...*/
  /* Anyway, 64-bit integer is at max 20 characters long. */
  sprintf(buf, "%d\n", getpid());
  buf[23] = '\0';
  write(fd, buf, strlen(buf));
  fchown(fd, nobody, nogrp);
  close(fd);

  signal(SIGTERM, (void(*)(int))handlexitsigs);
  signal(SIGINT, (void(*)(int))handlexitsigs);
  signal(SIGQUIT, (void(*)(int))handlexitsigs);
  /* should this handle ILL, ... (see signal(7)) */
}

static void printversion(void)
{
  struct iovec iv[4];

  iv[0].iov_base = TRG;
  iv[0].iov_len = sizeof TRG - 1;

  iv[1].iov_base = " ";
  iv[1].iov_len = 1;

  iv[2].iov_base = VERSION;
  iv[2].iov_len = sizeof VERSION - 1;

  iv[3].iov_base = ".\n";
  iv[3].iov_len = 2;

  writev(1, iv, 4);
}

int main(int argc GCCATTR_UNUSED, const char * argv[])
{
  uid_t nobody, nogrp;

  memset(conns, 0, sizeof conns);
  memset(&G, 0, sizeof G);
  FD_ZERO(&G.readfds);
  FD_SET(0, &G.readfds);

  TRACE(1, ("s: `%s', l = %d\n", ident_substr, ident_substr_len));

  if (argv[1])
    if (argv[1][0] == '-') {
      if (argv[1][1] == 'V')
	{
	  printversion();
	  return 0;
	}
      else
	{
        if (argv[1][1] == 'r')
	  {
	    G.randident = true;
	    srand(time(0));
	  }
	else
	  {
            char b[2]; b[0] = argv[1][1]; b[1]= '\0';

            writestrings(2, argv[0], ": invalid option -- ", b, ".\n",
                         "Usage: ", argv[0], " [-rV] ", IU_IN_USAGESTR "\n",
                         NULL);
            return 1;
	  }
	}}
    else
      SET_IU(argv[1], argc - 1);
  else
    SET_IU(nobodystr, 1);


#ifndef DEBUG
  close(1); /* not debugging, openlog() hopefully uses fd 1. */
#else
  close(3); /* debugging, TRACE uses fd 1, openlog() hopefully fd 3 */
#endif

  openlog("identd", LOG_CONS, LOG_DAEMON);

  {
    struct passwd * pw = getpwnam(nobodystr);

    if (pw)
      {
	nobody = pw->pw_uid;
	nogrp = pw->pw_gid;
      }
    else
      {
	syslog(LOG_CRIT, "Can not find user `nobody': %s,", strerrno());
	return -1;
      }
  }

  if (inetbind(getport()) < 0)
      return -1;

  /* */
  {
    int i;

    for (i = FCS; i < MAXCONNS + FCS; i++)
      close(i);
  }

#ifdef DEBUG
#ifndef LOG_PERROR
#define LOG_PERROR 0
#endif
  openlog("identd", LOG_PERROR, LOG_DAEMON);
#else /* not DEBUG */
  godaemon();
  openlog("identd", 0, LOG_DAEMON);
  close(2);
  signal(SIGHUP, SIG_IGN);
#endif /* DEBUG */

  signal(SIGPIPE, SIG_IGN); /* connection closed when writing (raises ???) */

  writepid(nobody, nogrp);

  setegid(nogrp); setgid(nogrp); setuid(nobody); seteuid(nobody);

  {
    int i;

    for (i = 0; i < 4; i++)
      {
	const char *	id = NULL;
	unsigned int	rv = 0;

	switch (i)
	  {
	  case 0: rv = (unsigned int)getegid(); id = "egid"; break;
	  case 1: rv = (unsigned int)getgid();  id = "gid";  break;
	  case 2: rv = (unsigned int)geteuid(); id = "euid"; break;
	  case 3: rv = (unsigned int)getuid();  id = "uid";  break;
	  }

	if (rv == 0)
	  {
	    syslog(LOG_ERR,
		   "Can not drop all root privileges (%s) !!! %s !!!",
		   id, strerrno());
	    delpidfile();
	    return -1;
	  }
      }
  }

  while (2)
  {
    fd_set		rfds = G.readfds;
    struct timeval	tv = { 15, 0 };
    int			i;
    int			tim = time(NULL);

    TRACE(1, ("calling select(): n = %d, rfds = 0x%x\n\n",
	      G.conncnt + FCS, *(int *)&rfds));

    select(G.conncnt + FCS, &rfds, NULL, NULL, G.conncnt? &tv: NULL);

    for (i = G.conncnt - 1; i >= 0; i--)
      {
	int s = i + FCS;

	if (FD_ISSET(s, &rfds))
	  {
	    char *		buf = conns[i].buf;
	    unsigned int	len = conns[i].len;
	    unsigned int	l;

	    TRACE(1, ("data socket fd_isset %d\n", s));

	    if ((int)(l = read(s, buf + len, sizeof conns[0].buf - len)) > 0)
	      {
		if (checkInput(buf, len, l))
		  {
		    reply(s, buf);
		    goto deleteconn;
		  }
		else if (len + l >= sizeof conns[0].buf)
		  {
		    replyError(s, "X-INVALID-REQUEST");
		    goto deleteconn;
		  }
		else
		  conns[i].len += l;
	      }
	    else
	      goto deleteconn;

	    conns[i].lasttime = tim;
	    continue;

	  deleteconn:
	    deleteConn(s);
	  }
	else
	  {
	    /* implement as time_after() in linux kernel sources ... */
	    if (conns[i].lasttime + MAXIDLETIME <= tim)
	      {
		replyError(s, "X-TIMEOUT");
		deleteConn(s);
	      }
	  }
      }

    if (FD_ISSET(0, &rfds))
      {
	int s = accept(0, NULL, 0);

	TRACE(1, ("server socket fd_isset, %d accepted\n", s));

	if (s < 0)
	  {
	    if (errno != EINTR) /* EINTR */
	      syslog(LOG_ERR, "accept: %s", strerrno());
	  }
	else
	  {
	    if (G.conncnt == MAXCONNS)
	      i = closeOldest();
	    else
	      i = G.conncnt++;

	    movefd(s, i + FCS); /* move if not already there */

	    FD_SET(i + FCS, &G.readfds);

	    conns[i].len = 0;
	    conns[i].lasttime = time(NULL);
	  }
      }
  }
}

static int parseAddrs(char * ptr, char ** myaddr, char ** heraddr);

static void replyError(int s, const char * buf)
{
  struct iovec iv[3];

  iv[0].iov_base = "0, 0 : ERROR : ";	iv[0].iov_len = 15;
  iv[1].iov_base = buf;			iv[1].iov_len = strlen(buf);
  iv[2].iov_base = "\r\n";		iv[2].iov_len = 2;

  writev(s, iv, 3);
}

static void reply(int s, char * buf)
{
  char * myaddr, *heraddr;

  myaddr = heraddr = NULL;

  if (parseAddrs(buf, &myaddr, &heraddr))
    replyError(s, "X-INVALID-REQUEST");
  else
    {
      struct iovec iv[6];
#ifdef XXXMULTI
      const char * iul = G.identuserlist[random() % G.identusers];
#endif

      iv[0].iov_base = myaddr;		iv[0].iov_len = strlen(myaddr);
      iv[1].iov_base = ", ";		iv[1].iov_len = 2;
      iv[2].iov_base = heraddr;		iv[2].iov_len = strlen(heraddr);
      iv[3].iov_base = checked_cast(const char[], void *, ident_substr);
      iv[3].iov_len = ident_substr_len;
#ifdef XXXMULTI
      iv[4].iov_base = checked_cast(const char *, void *, iul);
      iv[4].iov_len = strlen(iul);
#else
      if (G.randident)
	{
	  /* generate random string as reply: */
	  int i;
	  char randomstring[8];
	  int randlen = (random() % 6) + 3; /* random string length 3-8 */

	  /* have first char letter... */
	  randomstring[0] = alphanum[10 + random() % 52];

	  for (i = 1; i < randlen; i++)
	    randomstring[i] = alphanum[random() % 62];

	  iv[4].iov_base = checked_cast(char [], void *, randomstring);
	  iv[4].iov_len = randlen;
	}
      else
	{
          /* use usual behaviour */
          iv[4].iov_base = checked_cast(const char *, void *, G.identuser);
          iv[4].iov_len = strlen(G.identuser);
	}
#endif
      iv[5].iov_base = "\r\n";	iv[5].iov_len = 2;

      writev(s, iv, 6);
    }
}

static int chmatch(char c, const char * chars)
{
  for (; *chars; chars++)
    if (c == *chars)
      return 1;

  return 0;
}

static int skipchars(char ** p, const char * chars)
{
  while (chmatch(**p, chars))
    (*p)++;

  if (**p == '\r' || **p == '\n')
    return 0;

  return 1;
}

static int parseAddrs(char * ptr, char ** myaddr, char ** heraddr)
{
  /* parse <port-on-server> , <port-on-client> */

  if (! skipchars(&ptr, " \t"))
    return -1;

  *myaddr = ptr;

  if (! skipchars(&ptr, "1234567890"))
    return -1;

  if (! chmatch(*ptr, " \t,"))
    return -1;

  *ptr++ = '\0';

  if (! skipchars(&ptr, " \t,") )
    return -1;

  *heraddr = ptr;

  skipchars(&ptr, "1234567890");

  if (! chmatch(*ptr, " \n\r"))
    return -1;

  *ptr = '\0';

  return 0;
}

/* EOF */
