path: root/tdm/backend/xdmcp.c

/*

Copyright 1988, 1998  The Open Group
Copyright 2002 Sun Microsystems, Inc.  All rights reserved.
Copyright 2001-2004 Oswald Buddenhagen <ossi@kde.org>

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation.

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of a copyright holder shall
not be used in advertising or otherwise to promote the sale, use or
other dealings in this Software without prior written authorization
from the copyright holder.

*/

/*
 * xdm - display manager daemon
 * Author: Keith Packard, MIT X Consortium
 *
 * xdmcp.c - Support for XDMCP
 */

#include <config.h>

#ifdef XDMCP

#include "dm.h"
#include "dm_error.h"
#include "dm_auth.h"
#include "dm_socket.h"

#include <sys/types.h>
#include <ctype.h>

#include <netdb.h>
#if defined(IPv6) && defined(AF_INET6)
# include <arpa/inet.h>
#endif

/*
 * Forward reference
 */
static void broadcast_respond( struct sockaddr *from, int fromlen, int length, int fd );
static void forward_respond (struct sockaddr *from, int fromlen, int length, int fd);
static void manage( struct sockaddr *from, int fromlen, int length, int fd );
static void query_respond( struct sockaddr *from, int fromlen, int length, int fd );
static void request_respond( struct sockaddr *from, int fromlen, int length, int fd );
static void send_accept( struct sockaddr *to, int tolen, CARD32 sessionID, ARRAY8Ptr authenticationName, ARRAY8Ptr authenticationData, ARRAY8Ptr authorizationName, ARRAY8Ptr authorizationData, int fd );
static void send_alive( struct sockaddr *from, int fromlen, int length, int fd );
static void send_decline( struct sockaddr *to, int tolen, ARRAY8Ptr authenticationName, ARRAY8Ptr authenticationData, ARRAY8Ptr status, int fd );
static void send_failed( struct sockaddr *from, int fromlen, const char *name, CARD32 sessionID, const char *reason, int fd );
static void send_refuse( struct sockaddr *from, int fromlen, CARD32 sessionID, int fd );
static void send_unwilling( struct sockaddr *from, int fromlen, ARRAY8Ptr authenticationName, ARRAY8Ptr status, int fd );
static void send_willing( struct sockaddr *from, int fromlen, ARRAY8Ptr authenticationName, ARRAY8Ptr status, int fd );


static XdmcpBuffer buffer;

static void
sendForward( CARD16 connectionType, ARRAY8Ptr address, char *closure )
{
#ifdef AF_INET
	struct sockaddr_in in_addr;
#endif
#if defined(IPv6) && defined(AF_INET6)
	struct sockaddr_in6 in6_addr;
#endif
#ifdef AF_DECnet
#endif
	struct sockaddr *addr;
	int addrlen;

	switch (connectionType) {
#ifdef AF_INET
	case FamilyInternet:
		addr = (struct sockaddr *)&in_addr;
		bzero( (char *)&in_addr, sizeof(in_addr) );
# ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
		in_addr.sin_len = sizeof(in_addr);
# endif
		in_addr.sin_family = AF_INET;
		in_addr.sin_port = htons( (short)XDM_UDP_PORT );
		if (address->length != 4)
			return;
		memmove( (char *)&in_addr.sin_addr, address->data, address->length );
		addrlen = sizeof(struct sockaddr_in);
		break;
#endif
#if defined(IPv6) && defined(AF_INET6)
	case FamilyInternet6:
		addr = (struct sockaddr *)&in6_addr;
		bzero( (char *)&in6_addr, sizeof(in6_addr) );
# ifdef SIN6_LEN
		in6_addr.sin6_len = sizeof(in6_addr);
# endif
		in6_addr.sin6_family = AF_INET6;
		in6_addr.sin6_port = htons( (short)XDM_UDP_PORT );
		if (address->length != 16)
			return;
		memmove( (char *)&in6_addr.sin6_addr, address->data, address->length );
		addrlen = sizeof(struct sockaddr_in6);
		break;
#endif
#ifdef AF_DECnet
	case FamilyDECnet:
#endif
	default:
		return;
	}
	XdmcpFlush( (int)closure, &buffer, (XdmcpNetaddr)addr, addrlen );
	return;
}

static void
ClientAddress( struct sockaddr *from,
               ARRAY8Ptr addr, /* return */
               ARRAY8Ptr port, /* return */
               CARD16 *type ) /* return */
{
	int length, family;
	char *data;

	data = NetaddrPort( (XdmcpNetaddr)from, &length );
	XdmcpAllocARRAY8( port, length );
	memmove( port->data, data, length );
	port->length = length;

	family = ConvertAddr( (XdmcpNetaddr)from, &length, &data );
	XdmcpAllocARRAY8( addr, length );
	memmove( addr->data, data, length );
	addr->length = length;

	*type = family;
}

static void
all_query_respond( struct sockaddr *from, int fromlen,
                   ARRAYofARRAY8Ptr authenticationNames,
                   xdmOpCode type, int fd )
{
	ARRAY8Ptr authenticationName;
	ARRAY8 status;
	ARRAY8 addr;
	CARD16 connectionType;
	int family;
	int length;

	family = ConvertAddr( (XdmcpNetaddr)from, &length, (char**)&(addr.data) );
	addr.length = length; /* convert int to short */
	Debug( "all_query_respond: conntype=%d, addr=%02[*:hhx\n",
	       family, addr.length, addr.data );
	if (family < 0)
		return;
	connectionType = family;

	if (type == INDIRECT_QUERY)
		RememberIndirectClient( &addr, connectionType );
	else
		ForgetIndirectClient( &addr, connectionType );

	authenticationName = ChooseAuthentication( authenticationNames );
	if (Willing( &addr, connectionType, authenticationName, &status, type ))
		send_willing( from, fromlen, authenticationName, &status, fd );
	else
		if (type == QUERY)
			send_unwilling( from, fromlen, authenticationName, &status, fd );
	XdmcpDisposeARRAY8( &status );
}

static void
indirect_respond( struct sockaddr *from, int fromlen, int length, int fd )
{
	ARRAYofARRAY8 queryAuthenticationNames;
	ARRAY8 clientAddress;
	ARRAY8 clientPort;
	CARD16 connectionType;
	int expectedLen;
	int i;
	XdmcpHeader header;
	int localHostAsWell;

	Debug( "<indirect> respond %d\n", length );
	if (!XdmcpReadARRAYofARRAY8( &buffer, &queryAuthenticationNames ))
		return;
	expectedLen = 1;
	for (i = 0; i < (int)queryAuthenticationNames.length; i++)
		expectedLen += 2 + queryAuthenticationNames.data[i].length;
	if (length == expectedLen) {
		ClientAddress( from, &clientAddress, &clientPort, &connectionType );
		/*
		 * set up the forward query packet
		 */
		header.version = XDM_PROTOCOL_VERSION;
		header.opcode = (CARD16)FORWARD_QUERY;
		header.length = 0;
		header.length += 2 + clientAddress.length;
		header.length += 2 + clientPort.length;
		header.length += 1;
		for (i = 0; i < (int)queryAuthenticationNames.length; i++)
			header.length += 2 + queryAuthenticationNames.data[i].length;
		XdmcpWriteHeader( &buffer, &header );
		XdmcpWriteARRAY8( &buffer, &clientAddress );
		XdmcpWriteARRAY8( &buffer, &clientPort );
		XdmcpWriteARRAYofARRAY8( &buffer, &queryAuthenticationNames );

		localHostAsWell =
			ForEachMatchingIndirectHost( &clientAddress, connectionType,
			                             sendForward, (char *)fd );

		XdmcpDisposeARRAY8( &clientAddress );
		XdmcpDisposeARRAY8( &clientPort );
		if (localHostAsWell)
			all_query_respond( from, fromlen, &queryAuthenticationNames,
			                   INDIRECT_QUERY, fd );
	} else
		Debug( "<indirect> length error got %d expect %d\n",
		       length, expectedLen );
	XdmcpDisposeARRAYofARRAY8( &queryAuthenticationNames );
}

void
ProcessRequestSocket( int fd )
{
	XdmcpHeader header;
#if defined(IPv6) && defined(AF_INET6)
	struct sockaddr_storage addr;
#else
	struct sockaddr addr;
#endif
	int addrlen = sizeof(addr);

	Debug( "ProcessRequestSocket\n" );
	bzero( (char *)&addr, sizeof(addr) );
	if (!XdmcpFill( fd, &buffer, (XdmcpNetaddr)&addr, &addrlen )) {
		Debug( "XdmcpFill failed\n" );
		return;
	}
	if (!XdmcpReadHeader( &buffer, &header )) {
		Debug( "XdmcpReadHeader failed\n" );
		return;
	}
	if (header.version != XDM_PROTOCOL_VERSION) {
		Debug( "XDMCP header version read was %d, expected %d\n",
		       header.version, XDM_PROTOCOL_VERSION );
		return;
	}
	Debug( "header: %d %d %d\n", header.version, header.opcode, header.length );
	switch (header.opcode) {
	case BROADCAST_QUERY:
		broadcast_respond( (struct sockaddr *)&addr, addrlen, header.length, fd );
		break;
	case QUERY:
		query_respond( (struct sockaddr *)&addr, addrlen, header.length, fd );
		break;
	case INDIRECT_QUERY:
		indirect_respond( (struct sockaddr *)&addr, addrlen, header.length, fd );
		break;
	case FORWARD_QUERY:
		forward_respond ((struct sockaddr *)&addr, addrlen, header.length, fd);
		break;
	case REQUEST:
		request_respond( (struct sockaddr *)&addr, addrlen, header.length, fd );
		break;
	case MANAGE:
		manage( (struct sockaddr *)&addr, addrlen, header.length, fd );
		break;
	case KEEPALIVE:
		send_alive( (struct sockaddr *)&addr, addrlen, header.length, fd );
		break;
	}
}

/*
 * respond to a request on the UDP socket.
 */

static void
direct_query_respond( struct sockaddr *from, int fromlen,
                      int length, xdmOpCode type, int fd )
{
	ARRAYofARRAY8 queryAuthenticationNames;
	int expectedLen;
	int i;

	if (!XdmcpReadARRAYofARRAY8( &buffer, &queryAuthenticationNames ))
		return;
	expectedLen = 1;
	for (i = 0; i < (int)queryAuthenticationNames.length; i++)
		expectedLen += 2 + queryAuthenticationNames.data[i].length;
	if (length == expectedLen)
		all_query_respond( from, fromlen, &queryAuthenticationNames, type, fd );
	XdmcpDisposeARRAYofARRAY8( &queryAuthenticationNames );
}

static void
query_respond( struct sockaddr *from, int fromlen, int length, int fd )
{
	Debug( "<query> respond %d\n", length );
	direct_query_respond( from, fromlen, length, QUERY, fd );
}

static void
broadcast_respond( struct sockaddr *from, int fromlen, int length, int fd )
{
	direct_query_respond( from, fromlen, length, BROADCAST_QUERY, fd );
}

/* computes an X display name */

static char *
NetworkAddressToName( CARD16 connectionType, ARRAY8Ptr connectionAddress,
                      struct sockaddr *originalAddress, CARD16 displayNumber )
{
	switch (connectionType) {
	case FamilyInternet:
#if defined(IPv6) && defined(AF_INET6)
	case FamilyInternet6:
#endif
		{
			CARD8 *data;
			struct hostent *hostent;
			char *hostname = NULL;
			char *name;
			const char *localhost;
			int multiHomed = 0;
			int type;
#if defined(IPv6) && defined(AF_INET6)
			struct addrinfo  *ai = NULL, *nai, hints;
			char  dotted[INET6_ADDRSTRLEN];

			if (connectionType == FamilyInternet6)
				type = AF_INET6;
			else
#endif
				type = AF_INET;

			data = connectionAddress->data;
			hostent = gethostbyaddr( (char *)data,
			                         connectionAddress->length, type );
			if (hostent) {
				if (sourceAddress) {
#if defined(IPv6) && defined(AF_INET6)
					bzero( &hints, sizeof(hints) );
					hints.ai_flags = AI_CANONNAME;
					if (!getaddrinfo( hostent->h_name, NULL, &hints, &ai )) {
						hostname = ai->ai_canonname;
						for (nai = ai->ai_next; nai; nai = nai->ai_next)
							if (ai->ai_protocol == nai->ai_protocol &&
							    memcmp( ai->ai_addr, nai->ai_addr,
							            ai->ai_addrlen ))
								multiHomed = 1;
					}
#else
					hostent = gethostbyname( hostent->h_name );
					if (hostent && hostent->h_addrtype == AF_INET) {
						multiHomed = hostent->h_addr_list[1] != NULL;
						hostname = hostent->h_name;
					}
#endif
				} else
					hostname = hostent->h_name;
			}

			localhost = localHostname();

			/*
			 * protect against bogus host names
			 */
			if (hostname && *hostname && *hostname != '.' && !multiHomed) {
				if (!strcmp( localhost, hostname ))
					ASPrintf( &name, "localhost:%d", displayNumber );
				else {
					if (removeDomainname) {
						char *remoteDot;
						char *localDot;

						/* check for a common domain name.	This
						 * could reduce names by recognising common
						 * super-domain names as well, but I don't think
						 * this is as useful, and will confuse more
						 * people
						 */
						if ((localDot = strchr( localhost, '.' )) &&
						    (remoteDot = strchr( hostname, '.' )))
						{
							/* smash the name in place; it won't
							 * be needed later.
							 */
							if (!strcmp( localDot+1, remoteDot+1 ))
								*remoteDot = '\0';
						}
					}

					ASPrintf( &name, "%s:%d", hostname, displayNumber );
				}
			} else {
#if defined(IPv6) && defined(AF_INET6)
				if (multiHomed) {
					if (connectionType == FamilyInternet) {
						data = (CARD8 *)
							&((struct sockaddr_in *)originalAddress)->sin_addr;
					} else {
						data = (CARD8 *)
							&((struct sockaddr_in6 *)originalAddress)->sin6_addr;
					}
				}
				inet_ntop( type, data, dotted, sizeof(dotted) );
				ASPrintf( &name, "%s:%d", dotted, displayNumber );
#else
				if (multiHomed)
					data = (CARD8 *)
						&((struct sockaddr_in *)originalAddress)->sin_addr;
				ASPrintf( &name, "%[4|'.'hhu:%d", data, displayNumber );
#endif
			}
#if defined(IPv6) && defined(AF_INET6)
			if (ai)
				freeaddrinfo( ai );
#endif
			return name;
		}
#ifdef DNET
	case FamilyDECnet:
		return NULL;
#endif /* DNET */
	default:
		return NULL;
	}
}

/*ARGSUSED*/
static void
forward_respond ( struct sockaddr *from, int fromlen ATTR_UNUSED,
                 int length, int fd)
{
	ARRAY8 clientAddress;
	ARRAY8 clientPort;
	ARRAYofARRAY8 authenticationNames;
	struct sockaddr *client;
	int clientlen;
	int expectedLen;
	int i;

	Debug( "<forward> respond %d\n", length );
	clientAddress.length = 0;
	clientAddress.data = 0;
	clientPort.length = 0;
	clientPort.data = 0;
	authenticationNames.length = 0;
	authenticationNames.data = 0;
	if (XdmcpReadARRAY8( &buffer, &clientAddress ) &&
	    XdmcpReadARRAY8( &buffer, &clientPort ) &&
	    XdmcpReadARRAYofARRAY8( &buffer, &authenticationNames ))
	{
		expectedLen = 0;
		expectedLen += 2 + clientAddress.length;
		expectedLen += 2 + clientPort.length;
		expectedLen += 1; /* authenticationNames */
		for (i = 0; i < (int)authenticationNames.length; i++)
			expectedLen += 2 + authenticationNames.data[i].length;
		if (length == expectedLen) {
			int j;

			j = 0;
			for (i = 0; i < (int)clientPort.length; i++)
				j = j * 256 + clientPort.data[i];
			Debug( "<forward> client address (port %d) %[*hhu\n", j,
			       clientAddress.length, clientAddress.data );
			switch (from->sa_family) {
#ifdef AF_INET
			case AF_INET:
				{
					struct sockaddr_in in_addr;

					if (clientAddress.length != 4 || clientPort.length != 2)
						goto badAddress;
					bzero( (char *)&in_addr, sizeof(in_addr) );
#ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
					in_addr.sin_len = sizeof(in_addr);
#endif
					in_addr.sin_family = AF_INET;
					memmove( &in_addr.sin_addr, clientAddress.data, 4 );
					memmove( (char *)&in_addr.sin_port, clientPort.data, 2 );
					client = (struct sockaddr *)&in_addr;
					clientlen = sizeof(in_addr);
					all_query_respond( client, clientlen, &authenticationNames,
					                   FORWARD_QUERY, fd );
				}
				break;
#endif
#if defined(IPv6) && defined(AF_INET6)
			case AF_INET6:
				{
					struct sockaddr_in6 in6_addr;

					if (clientAddress.length != 16 || clientPort.length != 2)
						goto badAddress;
					bzero( (char *)&in6_addr, sizeof(in6_addr) );
#ifdef SIN6_LEN
					in6_addr.sin6_len = sizeof(in6_addr);
#endif
					in6_addr.sin6_family = AF_INET6;
					memmove( &in6_addr,clientAddress.data,clientAddress.length );
					memmove( (char *)&in6_addr.sin6_port, clientPort.data, 2 );
					client = (struct sockaddr *)&in6_addr;
					clientlen = sizeof(in6_addr);
					all_query_respond( client, clientlen, &authenticationNames,
					                   FORWARD_QUERY, fd );
				}
				break;
#endif
#ifdef AF_UNIX
			case AF_UNIX:
				{
					struct sockaddr_un un_addr;

					if (clientAddress.length >= sizeof(un_addr.sun_path))
						goto badAddress;
					bzero( (char *)&un_addr, sizeof(un_addr) );
					un_addr.sun_family = AF_UNIX;
					memmove( un_addr.sun_path, clientAddress.data, clientAddress.length );
					un_addr.sun_path[clientAddress.length] = '\0';
					client = (struct sockaddr *)&un_addr;
#if defined(HAVE_STRUCT_SOCKADDR_IN_SIN_LEN) && !defined(__Lynx__) && defined(UNIXCONN)
					un_addr.sun_len = strlen( un_addr.sun_path );
					clientlen = SUN_LEN( &un_addr );
#else
					clientlen = sizeof(un_addr);
#endif
					all_query_respond( client, clientlen, &authenticationNames,
					                   FORWARD_QUERY, fd );
				}
				break;
#endif
#ifdef AF_CHAOS
			case AF_CHAOS:
				goto badAddress;
#endif
#ifdef AF_DECnet
			case AF_DECnet:
				goto badAddress;
#endif
			}
		} else
			Debug( "<forward> length error got %d expect %d\n", length, expectedLen );
	}
  badAddress:
	XdmcpDisposeARRAY8( &clientAddress );
	XdmcpDisposeARRAY8( &clientPort );
	XdmcpDisposeARRAYofARRAY8( &authenticationNames );
}

static ARRAY8 Hostname;

static void
send_willing( struct sockaddr *from, int fromlen,
             ARRAY8Ptr authenticationName, ARRAY8Ptr status, int fd )
{
	XdmcpHeader header;

	Debug( "send <willing> %.*s %.*s\n", authenticationName->length,
	       authenticationName->data,
	       status->length,
	       status->data );
	header.version = XDM_PROTOCOL_VERSION;
	header.opcode = (CARD16)WILLING;
	header.length =
		6 + authenticationName->length + Hostname.length + status->length;
	XdmcpWriteHeader( &buffer, &header );
	XdmcpWriteARRAY8( &buffer, authenticationName );
	XdmcpWriteARRAY8( &buffer, &Hostname );
	XdmcpWriteARRAY8( &buffer, status );
	XdmcpFlush( fd, &buffer, (XdmcpNetaddr)from, fromlen );
}

static void
send_unwilling( struct sockaddr *from, int fromlen,
               ARRAY8Ptr authenticationName, ARRAY8Ptr status, int fd )
{
	XdmcpHeader header;

	Debug( "send <unwilling> %.*s %.*s\n", authenticationName->length,
	       authenticationName->data,
	       status->length,
	       status->data );
	header.version = XDM_PROTOCOL_VERSION;
	header.opcode = (CARD16)UNWILLING;
	header.length = 4 + Hostname.length + status->length;
	XdmcpWriteHeader( &buffer, &header );
	XdmcpWriteARRAY8( &buffer, &Hostname );
	XdmcpWriteARRAY8( &buffer, status );
	XdmcpFlush( fd, &buffer, (XdmcpNetaddr)from, fromlen );
}

static unsigned long globalSessionID;

#define NextSessionID() (++globalSessionID)

void init_session_id( void )
{
	/* Set randomly so we are unlikely to reuse id's from a previous
	 * incarnation so we don't say "Alive" to those displays.
	 * Start with low digits 0 to make debugging easier.
	 */
	globalSessionID = (time( (Time_t *)0 ) & 0x7fff) * 16000;

	Hostname.data = (char *)localHostname();
	Hostname.length = strlen( Hostname.data );
}

static ARRAY8 outOfMemory = { (CARD16)13, (CARD8Ptr)"Out of memory" };
static ARRAY8 noValidAddr = { (CARD16)16, (CARD8Ptr)"No valid address" };
static ARRAY8 noValidAuth = { (CARD16)22, (CARD8Ptr)"No valid authorization" };
static ARRAY8 noAuthentic = { (CARD16)29, (CARD8Ptr)"XDM has no authentication key" };

static void
request_respond( struct sockaddr *from, int fromlen, int length, int fd )
{
	CARD16 displayNumber;
	ARRAY16 connectionTypes;
	ARRAYofARRAY8 connectionAddresses;
	ARRAY8 authenticationName;
	ARRAY8 authenticationData;
	ARRAYofARRAY8 authorizationNames;
	ARRAY8 manufacturerDisplayID;
	ARRAY8Ptr reason = 0;
	int expectlen;
	int i, j;
	struct protoDisplay  *pdpy;
	ARRAY8 authorizationName, authorizationData;
	ARRAY8Ptr connectionAddress;

	Debug( "<request> respond %d\n", length );
	connectionTypes.data = 0;
	connectionAddresses.data = 0;
	authenticationName.data = 0;
	authenticationData.data = 0;
	authorizationNames.data = 0;
	authorizationName.length = 0;
	authorizationData.length = 0;
	manufacturerDisplayID.data = 0;
	if (XdmcpReadCARD16( &buffer, &displayNumber ) &&
	    XdmcpReadARRAY16( &buffer, &connectionTypes ) &&
	    XdmcpReadARRAYofARRAY8( &buffer, &connectionAddresses ) &&
	    XdmcpReadARRAY8( &buffer, &authenticationName ) &&
	    XdmcpReadARRAY8( &buffer, &authenticationData ) &&
	    XdmcpReadARRAYofARRAY8( &buffer, &authorizationNames ) &&
	    XdmcpReadARRAY8( &buffer, &manufacturerDisplayID ))
	{
		expectlen = 0;
		expectlen += 2; /* displayNumber */
		expectlen += 1 + 2 * connectionTypes.length; /* connectionTypes */
		expectlen += 1; /* connectionAddresses */
		for (i = 0; i < (int)connectionAddresses.length; i++)
			expectlen += 2 + connectionAddresses.data[i].length;
		expectlen += 2 + authenticationName.length; /* authenticationName */
		expectlen += 2 + authenticationData.length; /* authenticationData */
		expectlen += 1; /* authoriationNames */
		for (i = 0; i < (int)authorizationNames.length; i++)
			expectlen += 2 + authorizationNames.data[i].length;
		expectlen += 2 + manufacturerDisplayID.length; /* displayID */
		if (expectlen != length) {
			Debug( "<request> length error got %d expect %d\n",
			       length, expectlen );
			goto abort;
		}
		if (connectionTypes.length == 0 ||
		    connectionAddresses.length != connectionTypes.length)
		{
			reason = &noValidAddr;
			pdpy = 0;
			goto decline;
		}
		pdpy = FindProtoDisplay( (XdmcpNetaddr)from, fromlen, displayNumber );
		if (!pdpy) {

			/* Check this Display against the Manager's policy */
			reason = Accept( from, fromlen, displayNumber );
			if (reason)
				goto decline;

			/* Check the Display's stream services against Manager's policy */
			i = SelectConnectionTypeIndex( &connectionTypes,
			                               &connectionAddresses );
			if (i < 0) {
				reason = &noValidAddr;
				goto decline;
			}

			/* The Manager considers this a new session */
			connectionAddress = &connectionAddresses.data[i];
			pdpy = NewProtoDisplay( (XdmcpNetaddr)from, fromlen, displayNumber,
			                        connectionTypes.data[i], connectionAddress,
			                        NextSessionID() );
			Debug( "NewProtoDisplay %p\n", pdpy );
			if (!pdpy) {
				reason = &outOfMemory;
				goto decline;
			}
		}
		if (authorizationNames.length == 0)
			j = 0;
		else
			j = SelectAuthorizationTypeIndex( &authenticationName,
			                                  &authorizationNames );
		if (j < 0) {
			reason = &noValidAuth;
			goto decline;
		}
		if (!CheckAuthentication( pdpy,
		                          &manufacturerDisplayID,
		                          &authenticationName,
		                          &authenticationData ))
		{
			reason = &noAuthentic;
			goto decline;
		}
		if (j < (int)authorizationNames.length) {
			Xauth *auth;
			SetProtoDisplayAuthorization( pdpy,
			                              (unsigned short)authorizationNames.data[j].length,
			                              (char *)authorizationNames.data[j].data );
			auth = pdpy->xdmcpAuthorization;
			if (!auth)
				auth = pdpy->fileAuthorization;
			if (auth) {
				authorizationName.length = auth->name_length;
				authorizationName.data = (CARD8Ptr) auth->name;
				authorizationData.length = auth->data_length;
				authorizationData.data = (CARD8Ptr) auth->data;
			}
		}
		if (pdpy) {
			send_accept( from, fromlen, pdpy->sessionID,
			             &authenticationName,
			             &authenticationData,
			             &authorizationName,
			             &authorizationData, fd );
		} else {
  decline:
			send_decline( from, fromlen, &authenticationName,
			              &authenticationData,
			              reason, fd );
			if (pdpy)
				DisposeProtoDisplay( pdpy );
		}
	}
  abort:
	XdmcpDisposeARRAY16( &connectionTypes );
	XdmcpDisposeARRAYofARRAY8( &connectionAddresses );
	XdmcpDisposeARRAY8( &authenticationName );
	XdmcpDisposeARRAY8( &authenticationData );
	XdmcpDisposeARRAYofARRAY8( &authorizationNames );
	XdmcpDisposeARRAY8( &manufacturerDisplayID );
}

static void
send_accept( struct sockaddr *to, int tolen, CARD32 sessionID,
            ARRAY8Ptr authenticationName, ARRAY8Ptr authenticationData,
            ARRAY8Ptr authorizationName, ARRAY8Ptr authorizationData,
            int fd )
{
	XdmcpHeader header;

	Debug( "<accept> session ID %ld\n", (long)sessionID );
	header.version = XDM_PROTOCOL_VERSION;
	header.opcode = (CARD16)ACCEPT;
	header.length = 4; /* session ID */
	header.length += 2 + authenticationName->length;
	header.length += 2 + authenticationData->length;
	header.length += 2 + authorizationName->length;
	header.length += 2 + authorizationData->length;
	XdmcpWriteHeader( &buffer, &header );
	XdmcpWriteCARD32( &buffer, sessionID );
	XdmcpWriteARRAY8( &buffer, authenticationName );
	XdmcpWriteARRAY8( &buffer, authenticationData );
	XdmcpWriteARRAY8( &buffer, authorizationName );
	XdmcpWriteARRAY8( &buffer, authorizationData );
	XdmcpFlush( fd, &buffer, (XdmcpNetaddr)to, tolen );
}

static void
send_decline( struct sockaddr *to, int tolen,
             ARRAY8Ptr authenticationName, ARRAY8Ptr authenticationData,
             ARRAY8Ptr status, int fd )
{
	XdmcpHeader header;

	Debug( "<decline> %.*s\n", status->length, status->data );
	header.version = XDM_PROTOCOL_VERSION;
	header.opcode = (CARD16)DECLINE;
	header.length = 0;
	header.length += 2 + status->length;
	header.length += 2 + authenticationName->length;
	header.length += 2 + authenticationData->length;
	XdmcpWriteHeader( &buffer, &header );
	XdmcpWriteARRAY8( &buffer, status );
	XdmcpWriteARRAY8( &buffer, authenticationName );
	XdmcpWriteARRAY8( &buffer, authenticationData );
	XdmcpFlush( fd, &buffer, (XdmcpNetaddr)to, tolen );
}

static void
manage( struct sockaddr *from, int fromlen, int length, int fd )
{
	CARD32 sessionID;
	CARD16 displayNumber;
	ARRAY8 displayClass;
	int expectlen;
	struct protoDisplay *pdpy;
	struct display *d;
	char *name = NULL;
	char *class2 = NULL;
	XdmcpNetaddr from_save;
	ARRAY8 clientAddress, clientPort;
	CARD16 connectionType;

	Debug( "<manage> %d\n", length );
	displayClass.data = 0;
	displayClass.length = 0;
	if (XdmcpReadCARD32( &buffer, &sessionID ) &&
	    XdmcpReadCARD16( &buffer, &displayNumber ) &&
	    XdmcpReadARRAY8( &buffer, &displayClass ))
	{
		expectlen = 4 + /* session ID */
					2 + /* displayNumber */
					2 + displayClass.length; /* displayClass */
		if (expectlen != length) {
			Debug( "<manage> length error got %d expect %d\n", length, expectlen );
			goto abort;
		}
		pdpy = FindProtoDisplay( (XdmcpNetaddr)from, fromlen, displayNumber );
		Debug( "<manage> session ID %ld, pdpy %p\n", (long)sessionID, pdpy );
		if (!pdpy || pdpy->sessionID != sessionID) {
			/*
			 * We may have already started a session for this display
			 * but it hasn't seen the response in the form of an
			 * XOpenDisplay() yet. So check if it is in the list of active
			 * displays, and if so check that the session id's match.
			 * If all this is true, then we have a duplicate request that
			 * can be ignored.
			 */
			if (!pdpy &&
			    (d = FindDisplayByAddress( (XdmcpNetaddr)from, fromlen,
			                               displayNumber )) &&
			    d->sessionID == sessionID)
			{
					Debug( "manage: got duplicate pkt, ignoring\n" );
					goto abort;
			}
			Debug( "session ID %ld refused\n", (long)sessionID );
			if (pdpy)
				Debug( "existing session ID %ld\n", (long)pdpy->sessionID );
			send_refuse( from, fromlen, sessionID, fd );
		} else {
			name = NetworkAddressToName( pdpy->connectionType,
			                             &pdpy->connectionAddress,
			                             from,
			                             pdpy->displayNumber );
			if (!name) {
				Debug( "could not compute display name\n" );
				send_failed( from, fromlen, "(no name)", sessionID,
				             "out of memory", fd );
				goto abort;
			}
			Debug( "computed display name: %s\n", name );
			if ((d = FindDisplayByName( name ))) {
				Debug( "terminating active session for %s\n", d->name );
				StopDisplay( d );
			}
			if (displayClass.length) {
				if (!StrNDup( &class2, (char *)displayClass.data,
				              displayClass.length ))
				{
					send_failed( from, fromlen, name, sessionID,
					             "out of memory", fd );
					goto abort;
				}
			}
			if (!(from_save = (XdmcpNetaddr)Malloc( fromlen ))) {
				send_failed( from, fromlen, name, sessionID,
				             "out of memory", fd );
				goto abort;
			}
			memmove( from_save, from, fromlen );
			if (!(d = NewDisplay( name ))) {
				free( (char *)from_save );
				send_failed( from, fromlen, name, sessionID,
				             "out of memory", fd );
				goto abort;
			}
			d->class2 = class2;
			class2 = 0;
			d->displayType = dForeign | dTransient | dFromXDMCP;
			d->sessionID = pdpy->sessionID;
			d->from.data = (unsigned char *)from_save;
			d->from.length = fromlen;
			d->displayNumber = pdpy->displayNumber;
			ClientAddress( from, &clientAddress, &clientPort,
			               &connectionType );
			d->useChooser = 0;
			d->xdmcpFd = fd;
			if (IsIndirectClient( &clientAddress, connectionType )) {
				Debug( "IsIndirectClient\n" );
				ForgetIndirectClient( &clientAddress, connectionType );
				if (UseChooser( &clientAddress, connectionType )) {
					d->useChooser = 1;
					Debug( "use chooser for %s\n", d->name );
				}
			}
			d->clientAddr = clientAddress;
			d->connectionType = connectionType;
			d->remoteHost = NetworkAddressToHostname (pdpy->connectionType,
			                             &pdpy->connectionAddress);

			XdmcpDisposeARRAY8( &clientPort );
			if (pdpy->fileAuthorization) {
				d->authorizations = (Xauth **)Malloc( sizeof(Xauth *) );
				if (!d->authorizations) {
					free( (char *)from_save );
					free( (char *)d );
					send_failed( from, fromlen, name, sessionID,
					             "out of memory", fd );
					goto abort;
				}
				d->authorizations[0] = pdpy->fileAuthorization;
				d->authNum = 1;
				pdpy->fileAuthorization = 0;
			}
			DisposeProtoDisplay( pdpy );
			Debug( "starting display %s,%s\n", d->name, d->class2 );
			if (LoadDisplayResources( d ) < 0) {
				LogError( "Unable to read configuration for display %s; "
				          "stopping it.\n", d->name );
				StopDisplay( d );
			} else
				StartDisplay( d );
			CloseGetter();
		}
	}
abort:
	XdmcpDisposeARRAY8( &displayClass );
	if (name)
		free( (char *)name );
	if (class2)
		free( (char *)class2 );
}

void
SendFailed( struct display *d, const char *reason )
{
	Debug( "display start failed, sending <failed>\n" );
	send_failed( (struct sockaddr *)(d->from.data), d->from.length, d->name,
	             d->sessionID, reason, d->xdmcpFd );
}

static void
send_failed( struct sockaddr *from, int fromlen,
            const char *name, CARD32 sessionID, const char *reason, int fd )
{
	char buf[360];
	XdmcpHeader header;
	ARRAY8 status;

	sprintf( buf, "Session %ld failed for display %.260s: %s",
	         (long)sessionID, name, reason );
	Debug( "send_failed(%\"s)\n", buf );
	status.length = strlen( buf );
	status.data = (CARD8Ptr) buf;
	header.version = XDM_PROTOCOL_VERSION;
	header.opcode = (CARD16)FAILED;
	header.length = 6 + status.length;
	XdmcpWriteHeader( &buffer, &header );
	XdmcpWriteCARD32( &buffer, sessionID );
	XdmcpWriteARRAY8( &buffer, &status );
	XdmcpFlush( fd, &buffer, (XdmcpNetaddr)from, fromlen );
}

static void
send_refuse( struct sockaddr *from, int fromlen, CARD32 sessionID, int fd )
{
	XdmcpHeader header;

	Debug( "send <refuse> %ld\n", (long)sessionID );
	header.version = XDM_PROTOCOL_VERSION;
	header.opcode = (CARD16)REFUSE;
	header.length = 4;
	XdmcpWriteHeader( &buffer, &header );
	XdmcpWriteCARD32( &buffer, sessionID );
	XdmcpFlush( fd, &buffer, (XdmcpNetaddr)from, fromlen );
}

static void
send_alive( struct sockaddr *from, int fromlen, int length, int fd )
{
	CARD32 sessionID;
	CARD16 displayNumber;
	struct display *d;
	XdmcpHeader header;
	CARD8 sendRunning;
	CARD32 sendSessionID;

	Debug( "send <alive>\n" );
	if (XdmcpReadCARD16( &buffer, &displayNumber ) &&
	    XdmcpReadCARD32( &buffer, &sessionID ))
	{
		if (length == 6) {
			if (!(d = FindDisplayBySessionID( sessionID )))
				d = FindDisplayByAddress( (XdmcpNetaddr)from, fromlen,
				                          displayNumber );
			sendRunning = 0;
			sendSessionID = 0;
			if (d && d->status == running) {
				if (d->sessionID == sessionID)
					sendRunning = 1;
				sendSessionID = d->sessionID;
			}
			header.version = XDM_PROTOCOL_VERSION;
			header.opcode = (CARD16)ALIVE;
			header.length = 5;
			Debug( "<alive>: %d %ld\n", sendRunning, (long)sendSessionID );
			XdmcpWriteHeader( &buffer, &header );
			XdmcpWriteCARD8( &buffer, sendRunning );
			XdmcpWriteCARD32( &buffer, sendSessionID );
			XdmcpFlush( fd, &buffer, (XdmcpNetaddr)from, fromlen );
		}
	}
}

char *
NetworkAddressToHostname( CARD16 connectionType, ARRAY8Ptr connectionAddress )
{
	switch (connectionType) {
	case FamilyInternet:
#if defined(IPv6) && defined(AF_INET6)
	case FamilyInternet6:
#endif
		{
			struct hostent *he;
			char *name, *lname;
			char *myDot;
			int af_type;
#if defined(IPv6) && defined(AF_INET6)
			char dotted[INET6_ADDRSTRLEN];

			if (connectionType == FamilyInternet6)
				af_type = AF_INET6;
			else
#endif
				af_type = AF_INET;

			he = gethostbyaddr( (char *)connectionAddress->data,
			                    connectionAddress->length, af_type );
			if (he) {
#if defined(IPv6) && defined(AF_INET6)
				struct addrinfo *ai, *nai;
				if (!getaddrinfo( he->h_name, NULL, NULL, &ai )) {
					for (nai = ai; nai; nai = nai->ai_next) {
						if (af_type == nai->ai_family &&
						    !memcmp( nai->ai_family == AF_INET ?
						             (char *)&((struct sockaddr_in *)nai->ai_addr)->sin_addr :
						             (char *)&((struct sockaddr_in6 *)nai->ai_addr)->sin6_addr,
						             connectionAddress->data,
						             connectionAddress->length ))
						{
							freeaddrinfo( ai );
							goto oki;
						}
					}
					freeaddrinfo( ai );
#else
				if ((he = gethostbyname( he->h_name )) &&
				    he->h_addrtype == AF_INET)
				{
					int i;
					for (i = 0; he->h_addr_list[i]; i++)
						if (!memcmp( he->h_addr_list[i],
						             connectionAddress->data, 4 ))
							goto oki;
#endif
					LogError( "DNS spoof attempt or misconfigured resolver.\n" );
				}
				goto gotnone;
			  oki:
				if (StrDup( &name, he->h_name ) &&
				    !strchr( name, '.' ) &&
				    (myDot = strchr( localHostname(), '.' )))
				{
					if (ASPrintf( &lname, "%s%s", name, myDot )) {
#if defined(IPv6) && defined(AF_INET6)
						if (!getaddrinfo( lname, NULL, NULL, &ai )) {
							for (nai = ai; nai; nai = nai->ai_next) {
								if (af_type == nai->ai_family &&
								    !memcmp( nai->ai_family == AF_INET ?
								             (char *)&((struct sockaddr_in *)nai->ai_addr)->sin_addr :
								             (char *)&((struct sockaddr_in6 *)nai->ai_addr)->sin6_addr,
								             connectionAddress->data,
								             connectionAddress->length ))
								{
									freeaddrinfo( ai );
									free( name );
									return lname;
								}
							}
							freeaddrinfo( ai );
						}
#else
						if ((he = gethostbyname( lname )) &&
						    he->h_addrtype == AF_INET)
						{
							int i;
							for (i = 0; he->h_addr_list[i]; i++)
								if (!memcmp( he->h_addr_list[i],
								             connectionAddress->data, 4 ))
								{
									free( name );
									return lname;
								}
						}
#endif
						free( lname );
					}
				}
			} else {
			  gotnone:
				/* can't get name, so use emergency fallback */
#if defined(IPv6) && defined(AF_INET6)
				inet_ntop( af_type, connectionAddress->data,
				           dotted, sizeof(dotted) );
				StrDup( &name, dotted );
#else
				ASPrintf( &name, "%[4|'.'hhu", connectionAddress->data );
#endif
				LogWarn( "Cannot convert Internet address %s to host name\n",
				         name );
			}
			return name;
		}
#ifdef DNET
	case FamilyDECnet:
		break;
#endif /* DNET */
	default:
		break;
	}
	return 0;
}

#endif /* XDMCP */