path: root/floppyd.c

/*  Copyright 1999 Peter Schlaile.
 *  Copyright 1999-2005,2007-2009 Alain Knaff.
 *  This file is part of mtools.
 *
 *  Mtools 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  Mtools 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 Mtools.  If not, see <http://www.gnu.org/licenses/>.
 *
 * the floppyd daemon running on the local X-Server
 *
 * written by:
 *
 * Peter Schlaile
 *
 * udbz@rz.uni-karlsruhe.de
 *
 * Large parts of the network code shamelessly stolen from 
 * transproxy by John Saunders <john@nlc.net.au>
 *
 * Rewritten in C by Alain Knaff.  Apparently C++ is still not as
 * portable as C.  */

#define DEBUG 0

#include "sysincludes.h"
#include "llong.h"

#ifdef USE_FLOPPYD

#define USE_FLOPPYD_BUFFERED_IO  1

#include "sysincludes.h"
#include "grp.h"
#include <X11/Xlib.h>
#include <X11/Xauth.h>

#include "floppyd_io.h"

#ifndef SIGCLD
#define SIGCLD SIGCHLD
#endif

/* For Linux 1.2.13 */
#ifndef SOMAXCONN
#define SOMAXCONN 5
#endif

/*
   To compile:

   gcc -Wall floppyd.cpp -o floppyd -lX11

   floppyd

   Communication to the clients works the following way:

   Client sends his protocol-version. If the version between server and client
   differ: bail out.

   After that,we send our .Xauthority-file (a maximum of MAX_XAUTHORITY_LENGTH 
   Bytes long) to the server.

   The server then checks, if it already has a .Xauthority file. If so
   it is interpreted as LOCK-File for the floppy-device and the communication
   gets terminated.

   (What if we have 2 floppy devices? Well. Two floppy users with different
   home-directories should work nicely...)

   Now, the data is written to the .Xauthority file. Then we try to open
   a connection to the local X-Server. If this fails -> bail out.

   ***

   The data packets are built as follows:

   Base-packets: 1 Dword length, then data.
                 length is in Network-Byte order. (4 Bytes)

   Commands are: 1. Packet Opcode (length 1), 1. Data packet as parameter.

   Return: 1.Packet: 1. Dword: Bytes processed, 2. Dword: Error-Code

   ***

   TODO:
	  * Implement some IOCTL calls to format floppy disks or so...
	  * Read is somewhat dirty implemented. Tries multiple times to
	    read the expected bytes from the socket stream. Don't know
	    why this is necessary. Maybe the socket stream is nonblocking
	    or something IT SHOULD NOT BE!
	    
*/


#define MAX_XAUTHORITY_LENGTH    3000
#define MAX_DATA_REQUEST         3000000
#define BUFFERED_IO_SIZE         16348

unsigned int mtools_lock_timeout=30;

void serve_client(int sock, const char *const*device_name, unsigned int n_dev,
		  int close_stderr);


#ifdef USE_FLOPPYD_BUFFERED_IO
typedef struct io_buffer {
	Byte out_buffer[BUFFERED_IO_SIZE];
	Byte in_buffer[BUFFERED_IO_SIZE];
	
	size_t in_valid;
	size_t in_start;
	size_t out_valid;
	
	int handle;
} *io_buffer;

static io_buffer new_io_buffer (int _handle) {
	io_buffer buffer;

	buffer = New(struct io_buffer);

	buffer->handle = _handle;
	buffer->in_valid = buffer->in_start = 0;
	buffer->out_valid = 0;
	return buffer;
}


static void flush(io_buffer buffer) {
	if (buffer->out_valid) {
		if(write(buffer->handle, buffer->out_buffer, buffer->out_valid) < 0) {
			perror("floppyd flush");
		}
		buffer->out_valid = 0;
	}
}

static void free_io_buffer(io_buffer buffer) {
	flush(buffer);
	free(buffer);
}


static size_t buf_read (io_buffer buf, Byte* buffer, size_t nbytes) {
	size_t ret;
	
	if (nbytes <= buf->in_valid) {
		memcpy(buffer, buf->in_buffer+buf->in_start, nbytes);
		buf->in_valid -= nbytes;
		buf->in_start += nbytes;
		ret = nbytes;
	} else {
		if (buf->in_valid) 
			memcpy(buffer, buf->in_buffer+buf->in_start, 
				   buf->in_valid);
		nbytes -= buf->in_valid;
		buffer += buf->in_valid;
		if (nbytes > BUFFERED_IO_SIZE) {
			ssize_t rval = read(buf->handle, buffer, nbytes);
			if (rval >= 0) {
				ret = (size_t) rval + buf->in_valid;
			} else {
				perror("read error");
				exit(1);
			}
			buf->in_valid = buf->in_start = 0;
		} else {
			ssize_t rval = read(buf->handle, buf->in_buffer, 
					    BUFFERED_IO_SIZE);
			if (rval >= 0) {
				if (rval < (ssize_t) nbytes) {
					memcpy(buffer, buf->in_buffer,
					       (size_t) rval);
					ret = (size_t) rval + buf->in_valid;
					buf->in_valid = buf->in_start = 0;
				} else {
					size_t a;
					memcpy(buffer, buf->in_buffer, nbytes);
					buf->in_start = nbytes;
					a = buf->in_valid;
					buf->in_valid = (size_t) rval-nbytes;
					ret = a + nbytes;
				}
			} else {
				perror("read error");
				exit(1);
			}
		}
	}
	return ret;
}

static ssize_t buf_write(io_buffer buf, void* buffer, size_t nbytes) {
	if (buf->out_valid + nbytes > BUFFERED_IO_SIZE) {
		flush(buf);
		return write(buf->handle, buffer, nbytes);
	}
	memcpy(buf->out_buffer+buf->out_valid, buffer, nbytes);
	buf->out_valid += nbytes;
	return (ssize_t) nbytes;
}



#else

typedef int io_buffer;

io_buffer new_io_buffer (int handle) {
	return handle;
}


size_t buf_read (io_buffer handle, Byte* buffer, size_t nbytes) {
	return (read(handle, buffer, nbytes));
}

ssize_t buf_write(io_buffer handle, void* buffer, size_t nbytes) {
	return (write(handle, buffer, nbytes));
}


void free_io_buffer(io_buffer buffer) { }


void flush(io_buffer buffer) { }

#endif

typedef struct Packet {
	Byte* data;
	Dword len;
	Dword alloc_size;
} *Packet;

#include "byte_dword.h"

static Dword read_dword(io_buffer fp)
{
	Byte val[4];
	if (buf_read(fp, val, 4) < 4) {
		return 0xffffffff;
	}
	
	return byte2dword(val);
}

static void write_dword(io_buffer fp, Dword parm)
{
	Byte val[4];
	
	dword2byte(parm, val);
	
	buf_write(fp, val,4);
}


static Packet newPacket(void)
{
	Packet packet;

	packet = New(struct Packet);
	packet->data = NULL;
	packet->len = packet->alloc_size = 0;
	return packet;
}


static void destroyPacket(Packet packet)
{
	if(packet->data)
		free(packet->data);
	free(packet);
}

static void kill_packet(Packet packet)
{
	if(packet->data)
		free(packet->data);
	packet->data = NULL;
	packet->len = 0;
	packet->alloc_size = 0;
}

static void make_new(Packet packet, Dword l)
{
	if (l < packet->alloc_size) {
		packet->len = l;
		return;
	}
	kill_packet(packet);
	packet->len = packet->alloc_size = l;
	packet->data = malloc(l);
	memset(packet->data, 0, l);
}

static char send_packet(Packet packet, io_buffer fp)
{
	if (packet->data) {
		write_dword(fp, packet->len);
		buf_write(fp, packet->data, packet->len);
		flush(fp);
#if DEBUG
		fprintf(stderr, "send_packet(): Size: %li\n", packet->len);
#endif

#if DEBUG
		fprintf(stderr, "send_packet(): ");
		for (int i = 0; i < packet->len; i++) {
			fprintf(stderr, "%d ", packet->data[i]);
		}
		fprintf(stderr, "\n");
#endif		

	}
	return (packet->data != NULL);
}

static char recv_packet(Packet packet, io_buffer fp, Dword maxlength)
{
	Dword start;
	size_t l;
	Dword length = read_dword(fp);
#if DEBUG
	fprintf(stderr, "recv_packet(): Size: %li\n", length);
#endif
	if (length > maxlength || length == 0xffffffff ) {
		return 0;
	}
	make_new(packet, length);
	l = 0;
	for (start = 0; start < length; start += l) {
		l = buf_read(fp, packet->data+start, length-start);
		if (l == 0) {
			return 0;
		}
	}
	if (packet->len == 0) {
		return 0;
	}
#if DEBUG
	fprintf(stderr, "*** read: %li\n", packet->len);
#endif
	
#if DEBUG
	fprintf(stderr, "recv_packet(): ");
	for (i = 0; i < packet->len; i++) {
		fprintf(stderr, "%d ", packet->data[i]);
	}
	fprintf(stderr, "\n");
#endif		
	return 1;
}

static ssize_t read_packet(Packet packet, int fd, Dword length) {
	ssize_t ret;
	make_new(packet, length);
	ret = read(fd, packet->data, packet->len);
	if(ret < 0)
		return ret;
	packet->len = (Dword) ret;
	return 0;
}

static int write_packet(Packet packet, int fd) {
	return (int)write(fd, packet->data, packet->len);
}

static void put_dword(Packet packet, int my_index, Dword val) {
	dword2byte(val, packet->data+my_index);
}

static void put_qword(Packet packet, int my_index, Qword val) {
	qword2byte(val, packet->data+my_index);
}

static Dword get_dword(Packet packet, int my_index) {
	return byte2dword(packet->data+my_index);
}	

static Qword get_qword(Packet packet, int my_index) {
	return byte2qword(packet->data+my_index);
}	

static Dword get_length(Packet packet) {
	return packet->len;
}

static int eat(unsigned char **ptr, size_t *len, unsigned char c) {
    /* remove length + size code + terminating 0 */
    if (*len < c + 3)
	return -1;
    (*ptr) += c + 2;
    (*len) -= c + 2;
    return 0;
}

static const char *dispName;

static char XAUTHORITY[]="XAUTHORITY";

static char do_auth(io_buffer sock, unsigned int *version) 
{
	int fd;
	Display* displ;
	Packet proto_version = newPacket();
	Packet mit_cookie;
	unsigned char *ptr;
	size_t len;

	char authFile[41]="/tmp/floppyd.XXXXXX";
	unsigned char template[4096];

	Packet reply = newPacket();

	make_new(reply, 4);

	if (!recv_packet(proto_version, sock, 4)) {
		put_dword(reply, 0, AUTH_PACKETOVERSIZE);
		send_packet(reply, sock);
		destroyPacket(reply);
		destroyPacket(proto_version);
		return 0;
	}

	*version = get_dword(proto_version, 0);
	if (*version > FLOPPYD_PROTOCOL_VERSION || 
	    *version < FLOPPYD_PROTOCOL_VERSION_OLD) {
		/* fail if client requests a newer version than us */
		put_dword(reply, 0, AUTH_WRONGVERSION);
		send_packet(reply, sock);
		destroyPacket(reply);
		destroyPacket(proto_version);
		return 0;
	}

	if(*version == FLOPPYD_PROTOCOL_VERSION_OLD) {
		put_dword(reply, 0, AUTH_SUCCESS);
	} else {
		Dword cap = FLOPPYD_CAP_EXPLICIT_OPEN;
		if(sizeof(mt_off_t) >= 8) {
			cap |= FLOPPYD_CAP_LARGE_SEEK;
		}
		make_new(reply, 12);
		put_dword(reply, 0, AUTH_SUCCESS);
		put_dword(reply, 4, FLOPPYD_PROTOCOL_VERSION);
		put_dword(reply, 8, cap);
	}
	send_packet(reply, sock);
	destroyPacket(proto_version);

	make_new(reply, 4);
	mit_cookie = newPacket();
	if (!recv_packet(mit_cookie, sock, MAX_XAUTHORITY_LENGTH)) {
		put_dword(reply, 0, AUTH_PACKETOVERSIZE);
		send_packet(reply, sock);
		destroyPacket(reply);
		destroyPacket(mit_cookie);
		return 0;
	}

	umask(077);
	fd = mkstemp(authFile);
	if(fd == -1) {
		/* Different error than file exists */
		put_dword(reply, 0, AUTH_DEVLOCKED);
		send_packet(reply, sock);
		close(fd);
		destroyPacket(reply);
		destroyPacket(mit_cookie);
		return 0;
	}
#ifdef HAVE_SETENV
	setenv(XAUTHORITY, authFile, 1);
#else
	{
	  char *buffer=malloc(strlen(XAUTHORITY)+strlen(authFile)+2);
	  strcpy(buffer, XAUTHORITY);
	  strcat(buffer, "=");
	  strcat(buffer, authFile);
	  putenv(buffer);
	}
#endif

	ptr = template;
	ptr[4095] = 0;
	*ptr++ = 1;
	*ptr++ = 0;
	*ptr++ = 0;
	gethostname((char*)ptr+1, 4088);
	len = strlen((char*)ptr+1);
	*ptr++ = (unsigned char) len;
	ptr += len;
	*ptr++ = 0;
	*ptr++ = 1;
	*ptr++ = '0'; /* Display number */
	*ptr++ = '\0';

	if(write(fd, template, len+8) < (ssize_t) (len + 8)) {
		close(fd);
		return 0;
	}
	ptr = mit_cookie->data;
	len = mit_cookie->len;

	if (eat(&ptr,&len,1) ||    /* the "type"    */
	    eat(&ptr,&len,*ptr) || /* the hostname  */
	    eat(&ptr,&len,*ptr)) { /* the display number */
	    destroyPacket(mit_cookie);
	    unlink(XauFileName());
	    put_dword(reply, 0, AUTH_BADPACKET);
	    send_packet(reply, sock);
	    destroyPacket(reply);
	    return 0;
	}

	if(write(fd, ptr, len) < (ssize_t) len) {
		close(fd);
		return 0;
	}
	close(fd);

	destroyPacket(mit_cookie);

	displ = XOpenDisplay(dispName);
	if (!displ) {
		unlink(XauFileName());
		put_dword(reply, 0, AUTH_AUTHFAILED);
		send_packet(reply, sock);
		destroyPacket(reply);
		return 0;
	}
	XCloseDisplay(displ);

	put_dword(reply, 0, AUTH_SUCCESS);
	send_packet(reply, sock);
	destroyPacket(reply);
	unlink(XauFileName());
	return 1;
}

/*
 * Return the port number, in network order, of the specified service.
 */
static uint16_t getportnum(char *portnum)
{
	char		*digits = portnum;
	struct servent	*serv;
	uint16_t	port;

	for (port = 0; isdigit(*digits); ++digits)
		{
			port = (port * 10) + (uint8_t)(*digits - '0');
		}

	if ((*digits != '\0') || (port <= 0))
		{
			if ((serv = getservbyname(portnum, "tcp")) != NULL)
				{
					port = ntohs((uint16_t)serv->s_port);
				}
			else
				{
					port = 0;
				}
			endservent();
		}

#if DEBUG
	fprintf(stderr, "Port lookup %s -> %hd\n", portnum, port);
#endif

	return (port);
}

/*
 * Return the IP address of the specified host.
 */
static in_addr_t getipaddress(char *ipaddr)
{
	struct hostent	*host;
	in_addr_t ip;

	if (((ip = inet_addr(ipaddr)) == INADDR_NONE)
	    &&
		(strcmp(ipaddr, "255.255.255.255") != 0))
		{
			if ((host = gethostbyname(ipaddr)) != NULL)
				{
					memcpy(&ip, host->h_addr, sizeof(ip));
				}
			endhostent();
		}

#if DEBUG
	fprintf(stderr, "IP lookup %s -> 0x%08lx\n", ipaddr, ip);
#endif

	return (ip);
}

/*
 * Find the userid of the specified user.
 */
static uid_t getuserid(char *user)
{
	struct passwd	*pw;
	uid_t			uid;

	if ((pw = getpwnam(user)) != NULL)
		{
			uid = pw->pw_uid;
		}
	else if (*user == '#')
		{
			uid = (uid_t)atoi(&user[1]);
		}
	else
		{
#ifdef HAVE_GETUSERID
			id = getuserid("nobody");
#else
			uid = 65535;
#endif
		}

#if DEBUG
	fprintf(stderr, "User lookup %s -> %d\n", user, uid);
#endif

	endpwent();

	return (uid);
}

/*
 * Find the groupid of the specified user.
 */
static uid_t getgroupid(uid_t uid)
{
	struct passwd	*pw;
	gid_t			gid;

	if ((pw = getpwuid(uid)) != NULL)
		{
			gid = pw->pw_gid;
		}
	else
		{
#ifdef HAVE_GETGROUPID
			id = getgroupid(uid);
#else
			gid = 65535;
#endif
		}

#if DEBUG
	fprintf(stderr, "Group lookup %d -> %d\n", uid, gid);
#endif

	endpwent();

	return (gid);
}

/*
 * Bind to the specified ip and port.
 */
static int bind_to_port(in_addr_t bind_ip, uint16_t bind_port)
{
	struct sockaddr_in	addr;
	int					sock;

	/*
	 * Allocate a socket.
	 */
	if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
		{
			perror("socket()");
			exit(1);
		}

	/*
	 * Set the SO_REUSEADDR option for debugging.
	 */
	{
	 	int	on = 1;
		if(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, 
			      (char *)&on, sizeof(on)) < 0) {
			perror("setsockopt");
			exit(1);
		}
	}

	/*
	 * Set the address to listen to.
	 */
	addr.sin_family = AF_INET;
	addr.sin_port = htons(bind_port);
	addr.sin_addr.s_addr = bind_ip;

	/*
	 * Bind our socket to the above address.
	 */
	if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
		{
			perror("bind()");
			exit(1);
		}

	/*
	 * Establish a large listen backlog.
	 */
	if (listen(sock, SOMAXCONN) < 0)
		{
			perror("listen()");
			exit(1);
		}

	return (sock);
}

static int sockethandle_now = -1;
  
/*
 * Catch alarm signals and exit.
 */
static void alarm_signal(int a UNUSEDP) NORETURN;
static void alarm_signal(int a UNUSEDP)
{
	if (sockethandle_now != -1) {
		close(sockethandle_now);
		sockethandle_now = -1;
		unlink(XauFileName());
	}
	exit(1);
}


/*
 * This is the main loop when running as a server.
 */
static void server_main_loop(int sock, const char *const*device_name,
			     unsigned int n_dev) NORETURN;
static void server_main_loop(int sock, const char *const*device_name,
			     unsigned int n_dev)
{
	struct sockaddr_in	addr;
	unsigned int		len;

	/*
	 * Ignore dead servers so no zombies should be left hanging.
	 */
	signal(SIGCLD, SIG_IGN);

	for (;;) {
		int					new_sock;
		/*
		 * Accept an incoming connection.
		 */
		len = sizeof(addr);
		while ((new_sock = accept(sock, (struct sockaddr *)&addr, &len)) < 0){}
		
		/*
		 * Create a new process to handle the connection.
		 */
#if DEBUG == 0
		switch (fork()) {
			case -1:
				/*
				 * Under load conditions just ignore new connections.
				 */
				break;
				
			case 0:
				/*
				 * Start the proxy work in the new socket.
				 */
#endif
				serve_client(new_sock, device_name, n_dev, 0);
				exit(0);
#if DEBUG == 0
		}
#endif
		/*
		 * Close the socket as the child does the handling.
		 */
		close(new_sock);
		new_sock = -1;
	}
}

/*
 * Print some basic help information.
 */
static void usage(char *prog, const char *opt, int ret) NORETURN;
static void usage(char *prog, const char *opt, int ret)
{
	if (opt)
		{
			fprintf(stderr, "%s: %s\n", prog, opt);
		}
	fprintf(stderr, "usage: %s [-s port [-r user] [-b ipaddr]] devicename [Names of local host]\n", 
			prog);
	fprintf(stderr, "    -d          Run as a server (default port 5703 + DISPLAY)\n");
	fprintf(stderr, "    -s port     Run as a server bound to the specified port.\n");
	fprintf(stderr, "    -r user     Run as the specified user in server mode.\n");
	fprintf(stderr, "    -b ipaddr   Bind to the specified ipaddr in server mode.\n");
	fprintf(stderr, "    -l          Do not attempt to connect to localhost:0 to validate connection\n");
	exit(ret);
}


static char *makeDisplayName(int dispNr)
{
	char result[80];
	sprintf(result, ":%d.0", dispNr);
	return strdup(result);
}

int main (int argc, char** argv) 
{
	int sockfd = 0;
	int			arg;
	int			run_as_server = 0;
	in_addr_t		bind_ip = INADDR_ANY;
	uint16_t		bind_port = 0;
	uid_t			run_uid = 65535;
	gid_t			run_gid = 65535;
	char*			username = strdup("nobody");
	int			sock;

	const char *const* device_name = NULL; 
	const char *floppy0 = "/dev/fd0";
	unsigned int n_dev;


	/*
	 * Parse the command line arguments.
	 */
	if(argc > 1 && !strcmp(argv[0], "--help"))
		usage(argv[0], NULL, 0);
	while ((arg = getopt(argc, argv, "ds:r:b:x:h")) != EOF)
		{
			switch (arg)
				{
					case 'd':
						run_as_server = 1;
						break;
					case 's':
						run_as_server = 1;
						bind_port = getportnum(optarg);
						break;

					case 'r':
						free(username); username = strdup(optarg);
						run_uid = getuserid(optarg);
						run_gid = getgroupid(run_uid);
						break;

					case 'b':
						run_as_server = 1;
						bind_ip = getipaddress(optarg);
						break;
					case 'x':
						dispName = strdup(optarg);
						break;

					case 'h':
						usage(argv[0], NULL, 0);
					case '?':
						usage(argv[0], NULL, 1);
				}
		}

	if(optind < argc) {
		device_name = (const char * const *) argv + optind;
		n_dev = (unsigned int) (argc - optind);
	} else {
		device_name = &floppy0;
		n_dev = 1;
	}

	if(dispName == NULL)
		dispName = getenv("DISPLAY");
	if(dispName==NULL && bind_port != 0)
		dispName=makeDisplayName((unsigned short)(bind_port - 5703));
	if(dispName==NULL)		
		dispName=":0";

	if(bind_port == 0) {
		char *p = strchr(dispName,':');
		bind_port = FLOPPYD_DEFAULT_PORT;
		if(p != NULL)
			bind_port += atoi(p+1);
	}

	if(!run_as_server) {
		struct sockaddr_in	addr;
		unsigned int len = sizeof(addr);
		
		/* try to find out port that we are connected to */
		if(getsockname(0, (struct sockaddr*) &addr, &len) >= 0 && 
		   len == sizeof(addr)) {
			bind_port = ntohs(addr.sin_port);
		}
	}

	umask(0077);

	/*
	 * Test to make sure required args were provided and are valid.
	 */
	if (run_as_server && (bind_ip == INADDR_NONE)) {
		usage(argv[0], "The server ipaddr is invalid.", 1);
	}
	if (run_as_server && (bind_port == 0))	{
		usage(argv[0], "No server port was specified (or it was invalid).", 1);
	}


	/*
	 * See if we should run as a server.
	 */
	if (run_as_server) {
		/*
		 * Start by binding to the port, the child inherits this socket.
		 */
		sock = bind_to_port(bind_ip, bind_port);
		
		/*
		 * Start a server process. When DEBUG is defined, just run
		 * in the foreground.
		 */
#if DEBUG
		switch (0)
#else
			switch (fork())
#endif
				{
				case -1:
					perror("fork()");
					exit(1);
					
				case 0:
					/*
					 * Ignore some signals.
					 */
					signal(SIGHUP, SIG_IGN);
#if DEBUG
					signal(SIGINT, SIG_IGN);
#endif
					signal(SIGQUIT, SIG_IGN);
					signal(SIGTSTP, SIG_IGN);
					signal(SIGCONT, SIG_IGN);
					signal(SIGPIPE, alarm_signal);
					/*signal(SIGALRM, alarm_signal);*/
					
					/*
					 * Drop back to an untrusted user.
					 */
					setgid(run_gid);
					initgroups(username, run_gid);
					setuid(run_uid);
					
					/*
					 * Start a new session and group.
					 */
					setsid();
#ifdef HAVE_SETPGRP
#ifdef SETPGRP_VOID
					setpgrp();
#else
					setpgrp(0,0);
#endif
#endif
#if DEBUG
					close(2);
					open("/dev/null", O_WRONLY);
#endif
					/*
					 * Handle the server main loop.
					 */
					server_main_loop(sock, device_name,
							 n_dev);
				}
		
		/*
		 * Parent exits at this stage.
		 */
		exit(0);
	}

	signal(SIGHUP, alarm_signal);
#if DEBUG == 0
	signal(SIGINT, alarm_signal);
#endif
	signal(SIGQUIT, alarm_signal);
	signal(SIGTERM, alarm_signal);
	signal(SIGTSTP, SIG_IGN);
	signal(SIGCONT, SIG_IGN);
	signal(SIGPIPE, alarm_signal);
	/*signal(SIGALRM, alarm_signal);*/

	/* Starting from inetd */

	serve_client(sockfd, device_name, n_dev, 1);
	return 0;
}

static void send_reply(int rval, io_buffer sock, Dword len) {
	Packet reply = newPacket();

	make_new(reply, 8);
	put_dword(reply, 0, len);
	if (rval == -1) {
		put_dword(reply, 4, 0);
	} else {
		put_dword(reply, 4, (Dword) errno);
	}
	send_packet(reply, sock);
	destroyPacket(reply);
}

static void send_reply64(int rval, io_buffer sock, mt_off_t len) {
	Packet reply = newPacket();

	make_new(reply, 12);
	put_qword(reply, 0, (Qword) len);
	if (rval == -1) {
		put_dword(reply, 8, 0);
	} else {
		put_dword(reply, 8, (Dword) errno);
	}
	send_packet(reply, sock);
	destroyPacket(reply);
}

static void cleanup(int x UNUSEDP) NORETURN;
static void cleanup(int x UNUSEDP) {
	unlink(XauFileName());
	exit(-1);
}

#include "lockdev.h"

void serve_client(int sockhandle, const char *const*device_name,
		  unsigned int n_dev, int close_stderr) {
	Packet opcode;
	Packet parm;

	int readOnly;
	int devFd;
	io_buffer sock;
	int stopLoop;
	unsigned int version;
	int needSendReply=0;
	int rval=0;
	
	/*
	 * Set the keepalive socket option to on.
	 */
	{
		int		on = 1;
		if(setsockopt(sockhandle, SOL_SOCKET, 
			      SO_KEEPALIVE, (char *)&on, sizeof(on)) < 0) {
			perror("setsockopt");
			exit(1);
		}

	}


#if DEBUG == 0
	if(close_stderr) {
		close(2);
		open("/dev/null", O_WRONLY);
	}
#endif

	sock = new_io_buffer(sockhandle);
	
	/*
	 * Allow 60 seconds for any activity.
	 */
	alarm(60);
	
	version = 0;
	if (!do_auth(sock, &version)) {
		free_io_buffer(sock);
		return;
	}
	alarm(0);


	signal(SIGTERM, cleanup);
	signal(SIGALRM, cleanup);



	sockethandle_now = sockhandle;


	opcode = newPacket();
	parm = newPacket();

	devFd = -1;
	readOnly = 1;

	stopLoop = 0;
	if(version == FLOPPYD_PROTOCOL_VERSION_OLD) {
				/* old protocol */
		readOnly = 0;
		devFd = open(device_name[0], O_RDWR|O_LARGEFILE);
		
		if (devFd < 0) {
			readOnly = 1;
			devFd = open(device_name[0], 
				     O_RDONLY|O_LARGEFILE);
		}
		if(devFd < 0) {
			send_reply(0, sock, devFd >= 0 ? 0 : DWORD_ERR);
			stopLoop = 1;
		}
		lock_dev(devFd, !readOnly, NULL);
	}


	while(!stopLoop) {
		uint32_t dev_nr = 0;
		/*
		 * Allow 60 seconds for any activity.
		 */
		/*alarm(60);*/

		if (!recv_packet(opcode, sock, 1)) {
			break;
		}
/*		if(opcode->data[0] != OP_CLOSE)*/
		    recv_packet(parm, sock, MAX_DATA_REQUEST);

		/* on its own, floppyd does several small writes,
		 * running into the performance issue described in
		 * https://eklitzke.org/the-caveats-of-tcp-nodelay
		 * Cork fixes this by stalling the small writes until
		 * floppyd has assembled its entire message, thus
		 * preventing the bad interaction between Nagle's
		 * algorithm and Linux' delayed ACKs. Another fix
		 * would be to not send the small batches immediately,
		 * but instead keep them around and submit them to the
		 * kernel in one go using writev. However, writev is
		 * not available everywhere
		 */
		cork(sock->handle, 1);

		switch(opcode->data[0]) {
			case OP_OPRO:
				if(get_length(parm) >= 4)
					dev_nr = get_dword(parm,0);
				else
					dev_nr = 0;
				if(dev_nr >= n_dev) {
					send_reply(0, sock, DWORD_ERR);
					break;
				}

				devFd = open(device_name[dev_nr],
					     O_RDONLY | O_LARGEFILE);
#if DEBUG
				fprintf(stderr, "Device opened\n");
#endif
				if(devFd >= 0 && lock_dev(devFd, 0, NULL)) {
					send_reply(0, sock, DWORD_ERR);
					break;
				}
				send_reply(0, sock,
					   devFd >= 0 ? 0 : DWORD_ERR);
				readOnly = 1;
				break;
			case OP_OPRW:
				if(get_length(parm) >= 4)
					dev_nr = get_dword(parm,0);
				else
					dev_nr = 0;
				if(dev_nr >= n_dev) {
					send_reply(0, sock, DWORD_ERR);
					break;
				}
				devFd = open(device_name[dev_nr], O_RDWR);
				if(devFd >= 0 && lock_dev(devFd, 1, NULL)) {
					send_reply(0, sock, DWORD_ERR);
					break;
				}
				send_reply(0, sock,
					   devFd >= 0 ? 0 : DWORD_ERR);
				readOnly = 0;
				break;
			case OP_READ:
#if DEBUG
				fprintf(stderr, "READ:\n");
#endif
				if(read_packet(parm, devFd,
					       get_dword(parm, 0)) < 0)
					send_reply(devFd, sock, DWORD_ERR);
				else {
					send_reply(devFd, sock,
						   get_length(parm));
					send_packet(parm, sock);
				}
				break;
			case OP_WRITE:
#if DEBUG
				fprintf(stderr, "WRITE:\n");
#endif
				if(readOnly) {
					errno = -EROFS;
					rval = -1;
				} else {
					rval = write_packet(parm, devFd);
				}
				send_reply(devFd, sock, (Dword) rval);
				break;
			case OP_SEEK:
#if DEBUG
				fprintf(stderr, "SEEK:\n");
#endif

				lseek(devFd, 
				      get_dword(parm, 0),
				      (int) get_dword(parm, 4));
				send_reply(devFd, 
					   sock, 
					   (Dword) lseek(devFd, 0, SEEK_CUR));
				break;
			case OP_SEEK64:
				if(sizeof(mt_off_t) < 8) {
#if DEBUG
					fprintf(stderr, "64 bit requested where not available!\n");
#endif
					errno = EINVAL;
					send_reply(devFd, sock, DWORD_ERR);
					break;
				}
#if DEBUG
				fprintf(stderr, "SEEK64:\n");
#endif
				mt_lseek(devFd, 
					 (mt_off_t) get_qword(parm,0),
					 (int) get_dword(parm,8));
				send_reply64(devFd, 
					     sock, 
					     mt_lseek(devFd, 0, SEEK_CUR));
				break;
			case OP_FLUSH:
#if DEBUG
				fprintf(stderr, "FLUSH:\n");
#endif
				fsync(devFd);
				send_reply(devFd, sock, 0);
				break;
			case OP_CLOSE:
#if DEBUG
				fprintf(stderr, "CLOSE:\n");
#endif

				close(devFd);
				needSendReply = 1;
				rval = devFd;
				devFd = -1;
				stopLoop = 1;
				break;
			case OP_IOCTL:
				/* Unimplemented for now... */
				break;
			default:
#if DEBUG
				fprintf(stderr, "Invalid Opcode!\n");
#endif
				errno = EINVAL;
				send_reply(devFd, sock, DWORD_ERR);
				break;
		}
		cork(sock->handle, 0);
		kill_packet(parm);
		alarm(0);
	}

	

#if DEBUG
	fprintf(stderr, "Closing down...\n");
#endif

	if (devFd >= 0) {
		close(devFd);
		devFd = -1;
	}

	free_io_buffer(sock);

	/* remove "Lock"-File  */
	unlink(XauFileName());

	if(needSendReply)
	    send_reply(rval, sock, 0);
	destroyPacket(opcode);
	destroyPacket(parm);
}

#else
#include <stdio.h>

int main(int argc, char **argv) 
{
	puts("Floppyd support not included!");
	return -1;
}
	
#endif