path: root/os/xdmcp.c

/*
 * Copyright 1989 Network Computing Devices, Inc., Mountain View, California.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose and without fee is hereby granted, provided
 * that the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of N.C.D. not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  N.C.D. makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#ifdef WIN32
#include <X11/Xwinsock.h>
#define XSERV_t
#define TRANS_SERVER
#define TRANS_REOPEN
#include <X11/Xtrans/Xtrans.h>
#endif

#include <X11/Xos.h>

#if !defined(WIN32)
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <X11/X.h>
#include <X11/Xmd.h>
#include "misc.h"
#include <X11/Xpoll.h>
#include "osdep.h"
#include "input.h"
#include "dixstruct.h"
#include "opaque.h"
#include "site.h"

#ifdef STREAMSCONN
#include <tiuser.h>
#include <netconfig.h>
#include <netdir.h>
#endif

#define XSERV_t
#define TRANS_SERVER
#define TRANS_REOPEN
#include <X11/Xtrans/Xtrans.h>

#ifdef XDMCP
#undef REQUEST

#ifdef XDMCP_NO_IPV6
#undef IPv6
#endif

#include <X11/Xdmcp.h>

#define X_INCLUDE_NETDB_H
#include <X11/Xos_r.h>

static const char *defaultDisplayClass = COMPILEDDISPLAYCLASS;

static int xdmcpSocket, sessionSocket;
static xdmcp_states state;

#if defined(IPv6) && defined(AF_INET6)
static int xdmcpSocket6;
static struct sockaddr_storage req_sockaddr;
#else
static struct sockaddr_in req_sockaddr;
#endif
static int req_socklen;
static CARD32 SessionID;
static CARD32 timeOutTime;
static int timeOutRtx;
static CARD16 DisplayNumber;
static xdmcp_states XDM_INIT_STATE = XDM_OFF;

#ifdef HASXDMAUTH
static char *xdmAuthCookie;
#endif

static XdmcpBuffer buffer;

#if defined(IPv6) && defined(AF_INET6)

static struct addrinfo *mgrAddr;
static struct addrinfo *mgrAddrFirst;

#define SOCKADDR_TYPE		struct sockaddr_storage
#define SOCKADDR_FAMILY(s)	((struct sockaddr *)&(s))->sa_family

#ifdef BSD44SOCKETS
#define SOCKLEN_FIELD(s)	((struct sockaddr *)&(s))->sa_len
#define SOCKLEN_TYPE 		unsigned char
#else
#define SOCKLEN_TYPE 		unsigned int
#endif

#else

#define SOCKADDR_TYPE		struct sockaddr_in
#define SOCKADDR_FAMILY(s)	(s).sin_family

#ifdef BSD44SOCKETS
#define SOCKLEN_FIELD(s)	(s).sin_len
#define SOCKLEN_TYPE		unsigned char
#else
#define SOCKLEN_TYPE		size_t
#endif

#endif

static SOCKADDR_TYPE ManagerAddress;
static SOCKADDR_TYPE FromAddress;

#ifdef SOCKLEN_FIELD
#define ManagerAddressLen	SOCKLEN_FIELD(ManagerAddress)
#define FromAddressLen		SOCKLEN_FIELD(FromAddress)
#else
static SOCKLEN_TYPE ManagerAddressLen, FromAddressLen;
#endif

#if defined(IPv6) && defined(AF_INET6)
static struct multicastinfo {
    struct multicastinfo *next;
    struct addrinfo *ai;
    int hops;
} *mcastlist;
#endif

static void XdmcpAddHost(const struct sockaddr *from,
                         int fromlen,
                         ARRAY8Ptr AuthenticationName,
                         ARRAY8Ptr hostname, ARRAY8Ptr status);

static void XdmcpSelectHost(const struct sockaddr *host_sockaddr,
                            int host_len, ARRAY8Ptr AuthenticationName);

static void get_xdmcp_sock(void);

static void send_query_msg(void);

static void recv_willing_msg(struct sockaddr    *from,
                             int                fromlen,
                             unsigned           length);

static void send_request_msg(void);

static void recv_accept_msg(unsigned    length);

static void recv_decline_msg(unsigned   length);

static void send_manage_msg(void);

static void recv_refuse_msg(unsigned    length);

static void recv_failed_msg(unsigned    length);

static void send_keepalive_msg(void);

static void recv_alive_msg(unsigned     length );

static void XdmcpFatal(const char       *type,
                       ARRAY8Ptr        status);

static void XdmcpWarning(const char     *str);

static void get_manager_by_name(int     argc,
                                char    **argv,
                                int     i);

static void get_fromaddr_by_name(int    argc,
                                 char   **argv,
                                 int    i);

#if defined(IPv6) && defined(AF_INET6)
static int get_mcast_options(int        argc,
                             char       **argv,
                             int        i);
#endif

static void receive_packet(int socketfd);

static void send_packet(void);

static void timeout(void);

static void XdmcpBlockHandler(void              *data ,
                              struct timeval    **wt,
                              void              *LastSelectMask);

static void XdmcpWakeupHandler(void             *data,
                               int              i,
                               void             *LastSelectMask);

/*
 * Register the Manufacturer display ID
 */

static ARRAY8 ManufacturerDisplayID;

static void
XdmcpRegisterManufacturerDisplayID(const char *name, int length)
{
    int i;

    XdmcpDisposeARRAY8(&ManufacturerDisplayID);
    if (!XdmcpAllocARRAY8(&ManufacturerDisplayID, length))
        return;
    for (i = 0; i < length; i++)
        ManufacturerDisplayID.data[i] = (CARD8) name[i];
}

static unsigned short xdm_udp_port = XDM_UDP_PORT;
static Bool OneSession = FALSE;
static const char *xdm_from = NULL;

void
XdmcpUseMsg(void)
{
    ErrorF("-query host-name       contact named host for XDMCP\n");
    ErrorF("-broadcast             broadcast for XDMCP\n");
#if defined(IPv6) && defined(AF_INET6)
    ErrorF("-multicast [addr [hops]] IPv6 multicast for XDMCP\n");
#endif
    ErrorF("-indirect host-name    contact named host for indirect XDMCP\n");
    ErrorF("-port port-num         UDP port number to send messages to\n");
    ErrorF
        ("-from local-address    specify the local address to connect from\n");
    ErrorF("-once                  Terminate server after one session\n");
    ErrorF("-class display-class   specify display class to send in manage\n");
#ifdef HASXDMAUTH
    ErrorF("-cookie xdm-auth-bits  specify the magic cookie for XDMCP\n");
#endif
    ErrorF("-displayID display-id  manufacturer display ID for request\n");
}

static void
XdmcpDefaultListen(void)
{
    /* Even when configured --disable-listen-tcp, we should listen on tcp in
       XDMCP modes */
    _XSERVTransListen("tcp");
}

int
XdmcpOptions(int argc, char **argv, int i)
{
    if (strcmp(argv[i], "-query") == 0) {
        get_manager_by_name(argc, argv, i++);
        XDM_INIT_STATE = XDM_QUERY;
        AccessUsingXdmcp();
        XdmcpDefaultListen();
        return i + 1;
    }
    if (strcmp(argv[i], "-broadcast") == 0) {
        XDM_INIT_STATE = XDM_BROADCAST;
        AccessUsingXdmcp();
        XdmcpDefaultListen();
        return i + 1;
    }
#if defined(IPv6) && defined(AF_INET6)
    if (strcmp(argv[i], "-multicast") == 0) {
        i = get_mcast_options(argc, argv, ++i);
        XDM_INIT_STATE = XDM_MULTICAST;
        AccessUsingXdmcp();
        XdmcpDefaultListen();
        return i + 1;
    }
#endif
    if (strcmp(argv[i], "-indirect") == 0) {
        get_manager_by_name(argc, argv, i++);
        XDM_INIT_STATE = XDM_INDIRECT;
        AccessUsingXdmcp();
        XdmcpDefaultListen();
        return i + 1;
    }
    if (strcmp(argv[i], "-port") == 0) {
        if (++i == argc) {
            FatalError("Xserver: missing port number in command line\n");
        }
        xdm_udp_port = (unsigned short) atoi(argv[i]);
        return i + 1;
    }
    if (strcmp(argv[i], "-from") == 0) {
        get_fromaddr_by_name(argc, argv, ++i);
        return i + 1;
    }
    if (strcmp(argv[i], "-once") == 0) {
        OneSession = TRUE;
        return i + 1;
    }
    if (strcmp(argv[i], "-class") == 0) {
        if (++i == argc) {
            FatalError("Xserver: missing class name in command line\n");
        }
        defaultDisplayClass = argv[i];
        return i + 1;
    }
#ifdef HASXDMAUTH
    if (strcmp(argv[i], "-cookie") == 0) {
        if (++i == argc) {
            FatalError("Xserver: missing cookie data in command line\n");
        }
        xdmAuthCookie = argv[i];
        return i + 1;
    }
#endif
    if (strcmp(argv[i], "-displayID") == 0) {
        if (++i == argc) {
            FatalError("Xserver: missing displayID in command line\n");
        }
        XdmcpRegisterManufacturerDisplayID(argv[i], strlen(argv[i]));
        return i + 1;
    }
    return i;
}

/*
 * This section is a collection of routines for
 * registering server-specific data with the XDMCP
 * state machine.
 */

/*
 * Save all broadcast addresses away so BroadcastQuery
 * packets get sent everywhere
 */

#define MAX_BROADCAST	10

/* This stays sockaddr_in since IPv6 doesn't support broadcast */
static struct sockaddr_in BroadcastAddresses[MAX_BROADCAST];
static int NumBroadcastAddresses;

void
XdmcpRegisterBroadcastAddress(const struct sockaddr_in *addr)
{
    struct sockaddr_in *bcast;

    if (NumBroadcastAddresses >= MAX_BROADCAST)
        return;
    bcast = &BroadcastAddresses[NumBroadcastAddresses++];
    memset(bcast, 0, sizeof(struct sockaddr_in));
#ifdef BSD44SOCKETS
    bcast->sin_len = addr->sin_len;
#endif
    bcast->sin_family = addr->sin_family;
    bcast->sin_port = htons(xdm_udp_port);
    bcast->sin_addr = addr->sin_addr;
}

/*
 * Each authentication type is registered here; Validator
 * will be called to check all access attempts using
 * the specified authentication type
 */

static ARRAYofARRAY8 AuthenticationNames, AuthenticationDatas;
typedef struct _AuthenticationFuncs {
    ValidatorFunc Validator;
    GeneratorFunc Generator;
    AddAuthorFunc AddAuth;
} AuthenticationFuncsRec, *AuthenticationFuncsPtr;

static AuthenticationFuncsPtr AuthenticationFuncsList;

void
XdmcpRegisterAuthentication(const char *name,
                            int namelen,
                            const char *data,
                            int datalen,
                            ValidatorFunc Validator,
                            GeneratorFunc Generator, AddAuthorFunc AddAuth)
{
    int i;
    ARRAY8 AuthenticationName, AuthenticationData;
    static AuthenticationFuncsPtr newFuncs;

    if (!XdmcpAllocARRAY8(&AuthenticationName, namelen))
        return;
    if (!XdmcpAllocARRAY8(&AuthenticationData, datalen)) {
        XdmcpDisposeARRAY8(&AuthenticationName);
        return;
    }
    for (i = 0; i < namelen; i++)
        AuthenticationName.data[i] = name[i];
    for (i = 0; i < datalen; i++)
        AuthenticationData.data[i] = data[i];
    if (!(XdmcpReallocARRAYofARRAY8(&AuthenticationNames,
                                    AuthenticationNames.length + 1) &&
          XdmcpReallocARRAYofARRAY8(&AuthenticationDatas,
                                    AuthenticationDatas.length + 1) &&
          (newFuncs =
           malloc((AuthenticationNames.length +
                   1) * sizeof(AuthenticationFuncsRec))))) {
        XdmcpDisposeARRAY8(&AuthenticationName);
        XdmcpDisposeARRAY8(&AuthenticationData);
        return;
    }
    for (i = 0; i < AuthenticationNames.length - 1; i++)
        newFuncs[i] = AuthenticationFuncsList[i];
    newFuncs[AuthenticationNames.length - 1].Validator = Validator;
    newFuncs[AuthenticationNames.length - 1].Generator = Generator;
    newFuncs[AuthenticationNames.length - 1].AddAuth = AddAuth;
    free(AuthenticationFuncsList);
    AuthenticationFuncsList = newFuncs;
    AuthenticationNames.data[AuthenticationNames.length - 1] =
        AuthenticationName;
    AuthenticationDatas.data[AuthenticationDatas.length - 1] =
        AuthenticationData;
}

/*
 * Select the authentication type to be used; this is
 * set by the manager of the host to be connected to.
 */

static ARRAY8 noAuthenticationName = { (CARD16) 0, (CARD8Ptr) 0 };
static ARRAY8 noAuthenticationData = { (CARD16) 0, (CARD8Ptr) 0 };

static ARRAY8Ptr AuthenticationName = &noAuthenticationName;
static ARRAY8Ptr AuthenticationData = &noAuthenticationData;
static AuthenticationFuncsPtr AuthenticationFuncs;

static void
XdmcpSetAuthentication(const ARRAY8Ptr name)
{
    int i;

    for (i = 0; i < AuthenticationNames.length; i++)
        if (XdmcpARRAY8Equal(&AuthenticationNames.data[i], name)) {
            AuthenticationName = &AuthenticationNames.data[i];
            AuthenticationData = &AuthenticationDatas.data[i];
            AuthenticationFuncs = &AuthenticationFuncsList[i];
            break;
        }
}

/*
 * Register the host address for the display
 */

static ARRAY16 ConnectionTypes;
static ARRAYofARRAY8 ConnectionAddresses;
static long xdmcpGeneration;

void
XdmcpRegisterConnection(int type, const char *address, int addrlen)
{
    int i;
    CARD8 *newAddress;

    if (xdmcpGeneration != serverGeneration) {
        XdmcpDisposeARRAY16(&ConnectionTypes);
        XdmcpDisposeARRAYofARRAY8(&ConnectionAddresses);
        xdmcpGeneration = serverGeneration;
    }
    if (xdm_from != NULL) {     /* Only register the requested address */
        const void *regAddr = address;
        const void *fromAddr = NULL;
        int regAddrlen = addrlen;

        if (addrlen == sizeof(struct in_addr)) {
            if (SOCKADDR_FAMILY(FromAddress) == AF_INET) {
                fromAddr = &((struct sockaddr_in *) &FromAddress)->sin_addr;
            }
#if defined(IPv6) && defined(AF_INET6)
            else if ((SOCKADDR_FAMILY(FromAddress) == AF_INET6) &&
                     IN6_IS_ADDR_V4MAPPED(&
                                          ((struct sockaddr_in6 *)
                                           &FromAddress)->sin6_addr)) {
                fromAddr =
                    &((struct sockaddr_in6 *) &FromAddress)->sin6_addr.
                    s6_addr[12];
            }
#endif
        }
#if defined(IPv6) && defined(AF_INET6)
        else if (addrlen == sizeof(struct in6_addr)) {
            if (SOCKADDR_FAMILY(FromAddress) == AF_INET6) {
                fromAddr = &((struct sockaddr_in6 *) &FromAddress)->sin6_addr;
            }
            else if ((SOCKADDR_FAMILY(FromAddress) == AF_INET) &&
                     IN6_IS_ADDR_V4MAPPED((const struct in6_addr *) address)) {
                fromAddr = &((struct sockaddr_in *) &FromAddress)->sin_addr;
                regAddr =
                    &((struct sockaddr_in6 *) &address)->sin6_addr.s6_addr[12];
                regAddrlen = sizeof(struct in_addr);
            }
        }
#endif
        if (!fromAddr || memcmp(regAddr, fromAddr, regAddrlen) != 0) {
            return;
        }
    }
    if (ConnectionAddresses.length + 1 == 256)
        return;
    newAddress = malloc(addrlen * sizeof(CARD8));
    if (!newAddress)
        return;
    if (!XdmcpReallocARRAY16(&ConnectionTypes, ConnectionTypes.length + 1)) {
        free(newAddress);
        return;
    }
    if (!XdmcpReallocARRAYofARRAY8(&ConnectionAddresses,
                                   ConnectionAddresses.length + 1)) {
        free(newAddress);
        return;
    }
    ConnectionTypes.data[ConnectionTypes.length - 1] = (CARD16) type;
    for (i = 0; i < addrlen; i++)
        newAddress[i] = address[i];
    ConnectionAddresses.data[ConnectionAddresses.length - 1].data = newAddress;
    ConnectionAddresses.data[ConnectionAddresses.length - 1].length = addrlen;
}

/*
 * Register an Authorization Name.  XDMCP advertises this list
 * to the manager.
 */

static ARRAYofARRAY8 AuthorizationNames;

void
XdmcpRegisterAuthorizations(void)
{
    XdmcpDisposeARRAYofARRAY8(&AuthorizationNames);
    RegisterAuthorizations();
}

void
XdmcpRegisterAuthorization(const char *name, int namelen)
{
    ARRAY8 authName;
    int i;

    authName.data = malloc(namelen * sizeof(CARD8));
    if (!authName.data)
        return;
    if (!XdmcpReallocARRAYofARRAY8
        (&AuthorizationNames, AuthorizationNames.length + 1)) {
        free(authName.data);
        return;
    }
    for (i = 0; i < namelen; i++)
        authName.data[i] = (CARD8) name[i];
    authName.length = namelen;
    AuthorizationNames.data[AuthorizationNames.length - 1] = authName;
}

/*
 * Register the DisplayClass string
 */

static ARRAY8 DisplayClass;

static void
XdmcpRegisterDisplayClass(const char *name, int length)
{
    int i;

    XdmcpDisposeARRAY8(&DisplayClass);
    if (!XdmcpAllocARRAY8(&DisplayClass, length))
        return;
    for (i = 0; i < length; i++)
        DisplayClass.data[i] = (CARD8) name[i];
}

/*
 * initialize XDMCP; create the socket, compute the display
 * number, set up the state machine
 */

void
XdmcpInit(void)
{
    state = XDM_INIT_STATE;
#ifdef HASXDMAUTH
    if (xdmAuthCookie)
        XdmAuthenticationInit(xdmAuthCookie, strlen(xdmAuthCookie));
#endif
    if (state != XDM_OFF) {
        XdmcpRegisterAuthorizations();
        XdmcpRegisterDisplayClass(defaultDisplayClass,
                                  strlen(defaultDisplayClass));
        AccessUsingXdmcp();
        RegisterBlockAndWakeupHandlers(XdmcpBlockHandler, XdmcpWakeupHandler,
                                       (void *) 0);
        timeOutRtx = 0;
        DisplayNumber = (CARD16) atoi(display);
        get_xdmcp_sock();
        send_packet();
    }
}

void
XdmcpReset(void)
{
    state = XDM_INIT_STATE;
    if (state != XDM_OFF) {
        RegisterBlockAndWakeupHandlers(XdmcpBlockHandler, XdmcpWakeupHandler,
                                       (void *) 0);
        timeOutRtx = 0;
        send_packet();
    }
}

/*
 * Called whenever a new connection is created; notices the
 * first connection and saves it to terminate the session
 * when it is closed
 */

void
XdmcpOpenDisplay(int sock)
{
    if (state != XDM_AWAIT_MANAGE_RESPONSE)
        return;
    state = XDM_RUN_SESSION;
    timeOutTime = GetTimeInMillis() + XDM_DEF_DORMANCY * 1000;
    sessionSocket = sock;
}

void
XdmcpCloseDisplay(int sock)
{
    if ((state != XDM_RUN_SESSION && state != XDM_AWAIT_ALIVE_RESPONSE)
        || sessionSocket != sock)
        return;
    state = XDM_INIT_STATE;
    if (OneSession)
        dispatchException |= DE_TERMINATE;
    else
        dispatchException |= DE_RESET;
    isItTimeToYield = TRUE;
}

/*
 * called before going to sleep, this routine
 * may modify the timeout value about to be sent
 * to select; in this way XDMCP can do appropriate things
 * dynamically while starting up
 */

 /*ARGSUSED*/ static void
XdmcpBlockHandler(void *data, /* unused */
                  struct timeval **wt, void *pReadmask)
{
    fd_set *last_select_mask = (fd_set *) pReadmask;
    CARD32 millisToGo;

    if (state == XDM_OFF)
        return;
    FD_SET(xdmcpSocket, last_select_mask);
#if defined(IPv6) && defined(AF_INET6)
    if (xdmcpSocket6 >= 0)
        FD_SET(xdmcpSocket6, last_select_mask);
#endif
    if (timeOutTime == 0)
        return;
    millisToGo = timeOutTime - GetTimeInMillis();
    if ((int) millisToGo < 0)
        millisToGo = 0;
    AdjustWaitForDelay(wt, millisToGo);
}

/*
 * called after select returns; this routine will
 * recognise when XDMCP packets await and
 * process them appropriately
 */

 /*ARGSUSED*/ static void
XdmcpWakeupHandler(void *data,        /* unused */
                   int i, void *pReadmask)
{
    fd_set *last_select_mask = (fd_set *) pReadmask;

    if (state == XDM_OFF)
        return;
    if (i > 0) {
        if (FD_ISSET(xdmcpSocket, last_select_mask)) {
            receive_packet(xdmcpSocket);
            FD_CLR(xdmcpSocket, last_select_mask);
        }
#if defined(IPv6) && defined(AF_INET6)
        if (xdmcpSocket6 >= 0 && FD_ISSET(xdmcpSocket6, last_select_mask)) {
            receive_packet(xdmcpSocket6);
            FD_CLR(xdmcpSocket6, last_select_mask);
        }
#endif
    }
    else if (timeOutTime && (int) (GetTimeInMillis() - timeOutTime) >= 0) {
        if (state == XDM_RUN_SESSION) {
            state = XDM_KEEPALIVE;
            send_packet();
        }
        else
            timeout();
    }
}

/*
 * This routine should be called from the routine that drives the
 * user's host menu when the user selects a host
 */

static void
XdmcpSelectHost(const struct sockaddr *host_sockaddr,
                int host_len, ARRAY8Ptr auth_name)
{
    state = XDM_START_CONNECTION;
    memmove(&req_sockaddr, host_sockaddr, host_len);
    req_socklen = host_len;
    XdmcpSetAuthentication(auth_name);
    send_packet();
}

/*
 * !!! this routine should be replaced by a routine that adds
 * the host to the user's host menu. the current version just
 * selects the first host to respond with willing message.
 */

 /*ARGSUSED*/ static void
XdmcpAddHost(const struct sockaddr *from,
             int fromlen,
             ARRAY8Ptr auth_name, ARRAY8Ptr hostname, ARRAY8Ptr status)
{
    XdmcpSelectHost(from, fromlen, auth_name);
}

/*
 * A message is queued on the socket; read it and
 * do the appropriate thing
 */

static ARRAY8 UnwillingMessage = { (CARD8) 14, (CARD8 *) "Host unwilling" };

static void
receive_packet(int socketfd)
{
#if defined(IPv6) && defined(AF_INET6)
    struct sockaddr_storage from;
#else
    struct sockaddr_in from;
#endif
    int fromlen = sizeof(from);
    XdmcpHeader header;

    /* read message off socket */
    if (!XdmcpFill(socketfd, &buffer, (XdmcpNetaddr) &from, &fromlen))
        return;

    /* reset retransmission backoff */
    timeOutRtx = 0;

    if (!XdmcpReadHeader(&buffer, &header))
        return;

    if (header.version != XDM_PROTOCOL_VERSION)
        return;

    switch (header.opcode) {
    case WILLING:
        recv_willing_msg((struct sockaddr *) &from, fromlen, header.length);
        break;
    case UNWILLING:
        XdmcpFatal("Manager unwilling", &UnwillingMessage);
        break;
    case ACCEPT:
        recv_accept_msg(header.length);
        break;
    case DECLINE:
        recv_decline_msg(header.length);
        break;
    case REFUSE:
        recv_refuse_msg(header.length);
        break;
    case FAILED:
        recv_failed_msg(header.length);
        break;
    case ALIVE:
        recv_alive_msg(header.length);
        break;
    }
}

/*
 * send the appropriate message given the current state
 */

static void
send_packet(void)
{
    int rtx;

    switch (state) {
    case XDM_QUERY:
    case XDM_BROADCAST:
    case XDM_INDIRECT:
#if defined(IPv6)  && defined(AF_INET6)
    case XDM_MULTICAST:
#endif
        send_query_msg();
        break;
    case XDM_START_CONNECTION:
        send_request_msg();
        break;
    case XDM_MANAGE:
        send_manage_msg();
        break;
    case XDM_KEEPALIVE:
        send_keepalive_msg();
        break;
    default:
        break;
    }
    rtx = (XDM_MIN_RTX << timeOutRtx);
    if (rtx > XDM_MAX_RTX)
        rtx = XDM_MAX_RTX;
    timeOutTime = GetTimeInMillis() + rtx * 1000;
}

/*
 * The session is declared dead for some reason; too many
 * timeouts, or Keepalive failure.
 */

static void
XdmcpDeadSession(const char *reason)
{
    ErrorF("XDM: %s, declaring session dead\n", reason);
    state = XDM_INIT_STATE;
    isItTimeToYield = TRUE;
    dispatchException |= DE_RESET;
    timeOutTime = 0;
    timeOutRtx = 0;
    send_packet();
}

/*
 * Timeout waiting for an XDMCP response.
 */

static void
timeout(void)
{
    timeOutRtx++;
    if (state == XDM_AWAIT_ALIVE_RESPONSE && timeOutRtx >= XDM_KA_RTX_LIMIT) {
        XdmcpDeadSession("too many keepalive retransmissions");
        return;
    }
    else if (timeOutRtx >= XDM_RTX_LIMIT) {
        /* Quit if "-once" specified, otherwise reset and try again. */
        if (OneSession) {
            dispatchException |= DE_TERMINATE;
            ErrorF("XDM: too many retransmissions\n");
        }
        else {
            XdmcpDeadSession("too many retransmissions");
        }
        return;
    }

#if defined(IPv6) && defined(AF_INET6)
    if (state == XDM_COLLECT_QUERY || state == XDM_COLLECT_INDIRECT_QUERY) {
        /* Try next address */
        for (mgrAddr = mgrAddr->ai_next;; mgrAddr = mgrAddr->ai_next) {
            if (mgrAddr == NULL) {
                mgrAddr = mgrAddrFirst;
            }
            if (mgrAddr->ai_family == AF_INET || mgrAddr->ai_family == AF_INET6)
                break;
        }
#ifndef SIN6_LEN
        ManagerAddressLen = mgrAddr->ai_addrlen;
#endif
        memcpy(&ManagerAddress, mgrAddr->ai_addr, mgrAddr->ai_addrlen);
    }
#endif

    switch (state) {
    case XDM_COLLECT_QUERY:
        state = XDM_QUERY;
        break;
    case XDM_COLLECT_BROADCAST_QUERY:
        state = XDM_BROADCAST;
        break;
#if defined(IPv6) && defined(AF_INET6)
    case XDM_COLLECT_MULTICAST_QUERY:
        state = XDM_MULTICAST;
        break;
#endif
    case XDM_COLLECT_INDIRECT_QUERY:
        state = XDM_INDIRECT;
        break;
    case XDM_AWAIT_REQUEST_RESPONSE:
        state = XDM_START_CONNECTION;
        break;
    case XDM_AWAIT_MANAGE_RESPONSE:
        state = XDM_MANAGE;
        break;
    case XDM_AWAIT_ALIVE_RESPONSE:
        state = XDM_KEEPALIVE;
        break;
    default:
        break;
    }
    send_packet();
}

static int
XdmcpCheckAuthentication(ARRAY8Ptr Name, ARRAY8Ptr Data, int packet_type)
{
    return (XdmcpARRAY8Equal(Name, AuthenticationName) &&
            (AuthenticationName->length == 0 ||
             (*AuthenticationFuncs->Validator) (AuthenticationData, Data,
                                                packet_type)));
}

static int
XdmcpAddAuthorization(ARRAY8Ptr name, ARRAY8Ptr data)
{
    AddAuthorFunc AddAuth;

    if (AuthenticationFuncs && AuthenticationFuncs->AddAuth)
        AddAuth = AuthenticationFuncs->AddAuth;
    else
        AddAuth = AddAuthorization;
    return (*AddAuth) ((unsigned short) name->length,
                       (char *) name->data,
                       (unsigned short) data->length, (char *) data->data);
}

/*
 * from here to the end of this file are routines private
 * to the state machine.
 */

static void
get_xdmcp_sock(void)
{
#ifdef STREAMSCONN
    struct netconfig *nconf;

    if ((xdmcpSocket = t_open("/dev/udp", O_RDWR, 0)) < 0) {
        XdmcpWarning("t_open() of /dev/udp failed");
        return;
    }

    if (t_bind(xdmcpSocket, NULL, NULL) < 0) {
        XdmcpWarning("UDP socket creation failed");
        t_error("t_bind(xdmcpSocket) failed");
        t_close(xdmcpSocket);
        return;
    }

    /*
     * This part of the code looks contrived. It will actually fit in nicely
     * when the CLTS part of Xtrans is implemented.
     */

    if ((nconf = getnetconfigent("udp")) == NULL) {
        XdmcpWarning("UDP socket creation failed: getnetconfigent()");
        t_unbind(xdmcpSocket);
        t_close(xdmcpSocket);
        return;
    }

    if (netdir_options(nconf, ND_SET_BROADCAST, xdmcpSocket, NULL)) {
        XdmcpWarning("UDP set broadcast option failed: netdir_options()");
        freenetconfigent(nconf);
        t_unbind(xdmcpSocket);
        t_close(xdmcpSocket);
        return;
    }

    freenetconfigent(nconf);
#else
    int soopts = 1;

#if defined(IPv6) && defined(AF_INET6)
    if ((xdmcpSocket6 = socket(AF_INET6, SOCK_DGRAM, 0)) < 0)
        XdmcpWarning("INET6 UDP socket creation failed");
#endif
    if ((xdmcpSocket = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
        XdmcpWarning("UDP socket creation failed");
#ifdef SO_BROADCAST
    else if (setsockopt(xdmcpSocket, SOL_SOCKET, SO_BROADCAST, (char *) &soopts,
                        sizeof(soopts)) < 0)
        XdmcpWarning("UDP set broadcast socket-option failed");
#endif                          /* SO_BROADCAST */
    if (xdmcpSocket >= 0 && xdm_from != NULL) {
        if (bind(xdmcpSocket, (struct sockaddr *) &FromAddress,
                 FromAddressLen) < 0) {
            FatalError("Xserver: failed to bind to -from address: %s\n",
                       xdm_from);
        }
    }
#endif                          /* STREAMSCONN */
}

static void
send_query_msg(void)
{
    XdmcpHeader header;
    Bool broadcast = FALSE;

#if defined(IPv6) && defined(AF_INET6)
    Bool multicast = FALSE;
#endif
    int i;
    int socketfd = xdmcpSocket;

    header.version = XDM_PROTOCOL_VERSION;
    switch (state) {
    case XDM_QUERY:
        header.opcode = (CARD16) QUERY;
        state = XDM_COLLECT_QUERY;
        break;
    case XDM_BROADCAST:
        header.opcode = (CARD16) BROADCAST_QUERY;
        state = XDM_COLLECT_BROADCAST_QUERY;
        broadcast = TRUE;
        break;
#if defined(IPv6) && defined(AF_INET6)
    case XDM_MULTICAST:
        header.opcode = (CARD16) BROADCAST_QUERY;
        state = XDM_COLLECT_MULTICAST_QUERY;
        multicast = TRUE;
        break;
#endif
    case XDM_INDIRECT:
        header.opcode = (CARD16) INDIRECT_QUERY;
        state = XDM_COLLECT_INDIRECT_QUERY;
        break;
    default:
        break;
    }
    header.length = 1;
    for (i = 0; i < AuthenticationNames.length; i++)
        header.length += 2 + AuthenticationNames.data[i].length;

    XdmcpWriteHeader(&buffer, &header);
    XdmcpWriteARRAYofARRAY8(&buffer, &AuthenticationNames);
    if (broadcast) {
        for (i = 0; i < NumBroadcastAddresses; i++)
            XdmcpFlush(xdmcpSocket, &buffer,
                       (XdmcpNetaddr) &BroadcastAddresses[i],
                       sizeof(struct sockaddr_in));
    }
#if defined(IPv6) && defined(AF_INET6)
    else if (multicast) {
        struct multicastinfo *mcl;
        struct addrinfo *ai;

        for (mcl = mcastlist; mcl != NULL; mcl = mcl->next) {
            for (ai = mcl->ai; ai != NULL; ai = ai->ai_next) {
                if (ai->ai_family == AF_INET) {
                    unsigned char hopflag = (unsigned char) mcl->hops;

                    socketfd = xdmcpSocket;
                    setsockopt(socketfd, IPPROTO_IP, IP_MULTICAST_TTL,
                               &hopflag, sizeof(hopflag));
                }
                else if (ai->ai_family == AF_INET6) {
                    int hopflag6 = mcl->hops;

                    socketfd = xdmcpSocket6;
                    setsockopt(socketfd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS,
                               &hopflag6, sizeof(hopflag6));
                }
                else {
                    continue;
                }
                XdmcpFlush(socketfd, &buffer,
                           (XdmcpNetaddr) ai->ai_addr, ai->ai_addrlen);
                break;
            }
        }
    }
#endif
    else {
#if defined(IPv6) && defined(AF_INET6)
        if (SOCKADDR_FAMILY(ManagerAddress) == AF_INET6)
            socketfd = xdmcpSocket6;
#endif
        XdmcpFlush(socketfd, &buffer, (XdmcpNetaddr) &ManagerAddress,
                   ManagerAddressLen);
    }
}

static void
recv_willing_msg(struct sockaddr *from, int fromlen, unsigned length)
{
    ARRAY8 authenticationName;
    ARRAY8 hostname;
    ARRAY8 status;

    authenticationName.data = 0;
    hostname.data = 0;
    status.data = 0;
    if (XdmcpReadARRAY8(&buffer, &authenticationName) &&
        XdmcpReadARRAY8(&buffer, &hostname) &&
        XdmcpReadARRAY8(&buffer, &status)) {
        if (length == 6 + authenticationName.length +
            hostname.length + status.length) {
            switch (state) {
            case XDM_COLLECT_QUERY:
                XdmcpSelectHost(from, fromlen, &authenticationName);
                break;
            case XDM_COLLECT_BROADCAST_QUERY:
#if defined(IPv6) && defined(AF_INET6)
            case XDM_COLLECT_MULTICAST_QUERY:
#endif
            case XDM_COLLECT_INDIRECT_QUERY:
                XdmcpAddHost(from, fromlen, &authenticationName, &hostname,
                             &status);
                break;
            default:
                break;
            }
        }
    }
    XdmcpDisposeARRAY8(&authenticationName);
    XdmcpDisposeARRAY8(&hostname);
    XdmcpDisposeARRAY8(&status);
}

static void
send_request_msg(void)
{
    XdmcpHeader header;
    int length;
    int i;
    CARD16 XdmcpConnectionType;
    ARRAY8 authenticationData;
    int socketfd = xdmcpSocket;

    switch (SOCKADDR_FAMILY(ManagerAddress)) {
    case AF_INET:
        XdmcpConnectionType = FamilyInternet;
        break;
#if defined(IPv6) && defined(AF_INET6)
    case AF_INET6:
        XdmcpConnectionType = FamilyInternet6;
        break;
#endif
    default:
        XdmcpConnectionType = 0xffff;
        break;
    }

    header.version = XDM_PROTOCOL_VERSION;
    header.opcode = (CARD16) REQUEST;

    length = 2;                 /* display number */
    length += 1 + 2 * ConnectionTypes.length;   /* connection types */
    length += 1;                /* connection addresses */
    for (i = 0; i < ConnectionAddresses.length; i++)
        length += 2 + ConnectionAddresses.data[i].length;
    authenticationData.length = 0;
    authenticationData.data = 0;
    if (AuthenticationFuncs) {
        (*AuthenticationFuncs->Generator) (AuthenticationData,
                                           &authenticationData, REQUEST);
    }
    length += 2 + AuthenticationName->length;   /* authentication name */
    length += 2 + authenticationData.length;    /* authentication data */
    length += 1;                /* authorization names */
    for (i = 0; i < AuthorizationNames.length; i++)
        length += 2 + AuthorizationNames.data[i].length;
    length += 2 + ManufacturerDisplayID.length; /* display ID */
    header.length = length;

    if (!XdmcpWriteHeader(&buffer, &header)) {
        XdmcpDisposeARRAY8(&authenticationData);
        return;
    }
    XdmcpWriteCARD16(&buffer, DisplayNumber);
    XdmcpWriteCARD8(&buffer, ConnectionTypes.length);

    /* The connection array is send reordered, so that connections of   */
    /* the same address type as the XDMCP manager connection are send   */
    /* first. This works around a bug in xdm. mario@klebsch.de          */
    for (i = 0; i < (int) ConnectionTypes.length; i++)
        if (ConnectionTypes.data[i] == XdmcpConnectionType)
            XdmcpWriteCARD16(&buffer, ConnectionTypes.data[i]);
    for (i = 0; i < (int) ConnectionTypes.length; i++)
        if (ConnectionTypes.data[i] != XdmcpConnectionType)
            XdmcpWriteCARD16(&buffer, ConnectionTypes.data[i]);

    XdmcpWriteCARD8(&buffer, ConnectionAddresses.length);
    for (i = 0; i < (int) ConnectionAddresses.length; i++)
        if ((i < ConnectionTypes.length) &&
            (ConnectionTypes.data[i] == XdmcpConnectionType))
            XdmcpWriteARRAY8(&buffer, &ConnectionAddresses.data[i]);
    for (i = 0; i < (int) ConnectionAddresses.length; i++)
        if ((i >= ConnectionTypes.length) ||
            (ConnectionTypes.data[i] != XdmcpConnectionType))
            XdmcpWriteARRAY8(&buffer, &ConnectionAddresses.data[i]);

    XdmcpWriteARRAY8(&buffer, AuthenticationName);
    XdmcpWriteARRAY8(&buffer, &authenticationData);
    XdmcpDisposeARRAY8(&authenticationData);
    XdmcpWriteARRAYofARRAY8(&buffer, &AuthorizationNames);
    XdmcpWriteARRAY8(&buffer, &ManufacturerDisplayID);
#if defined(IPv6) && defined(AF_INET6)
    if (SOCKADDR_FAMILY(req_sockaddr) == AF_INET6)
        socketfd = xdmcpSocket6;
#endif
    if (XdmcpFlush(socketfd, &buffer,
                   (XdmcpNetaddr) &req_sockaddr, req_socklen))
        state = XDM_AWAIT_REQUEST_RESPONSE;
}

static void
recv_accept_msg(unsigned length)
{
    CARD32 AcceptSessionID;
    ARRAY8 AcceptAuthenticationName, AcceptAuthenticationData;
    ARRAY8 AcceptAuthorizationName, AcceptAuthorizationData;

    if (state != XDM_AWAIT_REQUEST_RESPONSE)
        return;
    AcceptAuthenticationName.data = 0;
    AcceptAuthenticationData.data = 0;
    AcceptAuthorizationName.data = 0;
    AcceptAuthorizationData.data = 0;
    if (XdmcpReadCARD32(&buffer, &AcceptSessionID) &&
        XdmcpReadARRAY8(&buffer, &AcceptAuthenticationName) &&
        XdmcpReadARRAY8(&buffer, &AcceptAuthenticationData) &&
        XdmcpReadARRAY8(&buffer, &AcceptAuthorizationName) &&
        XdmcpReadARRAY8(&buffer, &AcceptAuthorizationData)) {
        if (length == 12 + AcceptAuthenticationName.length +
            AcceptAuthenticationData.length +
            AcceptAuthorizationName.length + AcceptAuthorizationData.length) {
            if (!XdmcpCheckAuthentication(&AcceptAuthenticationName,
                                          &AcceptAuthenticationData, ACCEPT)) {
                XdmcpFatal("Authentication Failure", &AcceptAuthenticationName);
            }
            /* permit access control manipulations from this host */
            AugmentSelf(&req_sockaddr, req_socklen);
            /* if the authorization specified in the packet fails
             * to be acceptable, enable the local addresses
             */
            if (!XdmcpAddAuthorization(&AcceptAuthorizationName,
                                       &AcceptAuthorizationData)) {
                AddLocalHosts();
            }
            SessionID = AcceptSessionID;
            state = XDM_MANAGE;
            send_packet();
        }
    }
    XdmcpDisposeARRAY8(&AcceptAuthenticationName);
    XdmcpDisposeARRAY8(&AcceptAuthenticationData);
    XdmcpDisposeARRAY8(&AcceptAuthorizationName);
    XdmcpDisposeARRAY8(&AcceptAuthorizationData);
}

static void
recv_decline_msg(unsigned length)
{
    ARRAY8 status, DeclineAuthenticationName, DeclineAuthenticationData;

    status.data = 0;
    DeclineAuthenticationName.data = 0;
    DeclineAuthenticationData.data = 0;
    if (XdmcpReadARRAY8(&buffer, &status) &&
        XdmcpReadARRAY8(&buffer, &DeclineAuthenticationName) &&
        XdmcpReadARRAY8(&buffer, &DeclineAuthenticationData)) {
        if (length == 6 + status.length +
            DeclineAuthenticationName.length +
            DeclineAuthenticationData.length &&
            XdmcpCheckAuthentication(&DeclineAuthenticationName,
                                     &DeclineAuthenticationData, DECLINE)) {
            XdmcpFatal("Session declined", &status);
        }
    }
    XdmcpDisposeARRAY8(&status);
    XdmcpDisposeARRAY8(&DeclineAuthenticationName);
    XdmcpDisposeARRAY8(&DeclineAuthenticationData);
}

static void
send_manage_msg(void)
{
    XdmcpHeader header;
    int socketfd = xdmcpSocket;

    header.version = XDM_PROTOCOL_VERSION;
    header.opcode = (CARD16) MANAGE;
    header.length = 8 + DisplayClass.length;

    if (!XdmcpWriteHeader(&buffer, &header))
        return;
    XdmcpWriteCARD32(&buffer, SessionID);
    XdmcpWriteCARD16(&buffer, DisplayNumber);
    XdmcpWriteARRAY8(&buffer, &DisplayClass);
    state = XDM_AWAIT_MANAGE_RESPONSE;
#if defined(IPv6) && defined(AF_INET6)
    if (SOCKADDR_FAMILY(req_sockaddr) == AF_INET6)
        socketfd = xdmcpSocket6;
#endif
    XdmcpFlush(socketfd, &buffer, (XdmcpNetaddr) &req_sockaddr, req_socklen);
}

static void
recv_refuse_msg(unsigned length)
{
    CARD32 RefusedSessionID;

    if (state != XDM_AWAIT_MANAGE_RESPONSE)
        return;
    if (length != 4)
        return;
    if (XdmcpReadCARD32(&buffer, &RefusedSessionID)) {
        if (RefusedSessionID == SessionID) {
            state = XDM_START_CONNECTION;
            send_packet();
        }
    }
}

static void
recv_failed_msg(unsigned length)
{
    CARD32 FailedSessionID;
    ARRAY8 status;

    if (state != XDM_AWAIT_MANAGE_RESPONSE)
        return;
    status.data = 0;
    if (XdmcpReadCARD32(&buffer, &FailedSessionID) &&
        XdmcpReadARRAY8(&buffer, &status)) {
        if (length == 6 + status.length && SessionID == FailedSessionID) {
            XdmcpFatal("Session failed", &status);
        }
    }
    XdmcpDisposeARRAY8(&status);
}

static void
send_keepalive_msg(void)
{
    XdmcpHeader header;
    int socketfd = xdmcpSocket;

    header.version = XDM_PROTOCOL_VERSION;
    header.opcode = (CARD16) KEEPALIVE;
    header.length = 6;

    XdmcpWriteHeader(&buffer, &header);
    XdmcpWriteCARD16(&buffer, DisplayNumber);
    XdmcpWriteCARD32(&buffer, SessionID);

    state = XDM_AWAIT_ALIVE_RESPONSE;
#if defined(IPv6) && defined(AF_INET6)
    if (SOCKADDR_FAMILY(req_sockaddr) == AF_INET6)
        socketfd = xdmcpSocket6;
#endif
    XdmcpFlush(socketfd, &buffer, (XdmcpNetaddr) &req_sockaddr, req_socklen);
}

static void
recv_alive_msg(unsigned length)
{
    CARD8 SessionRunning;
    CARD32 AliveSessionID;

    if (state != XDM_AWAIT_ALIVE_RESPONSE)
        return;
    if (length != 5)
        return;
    if (XdmcpReadCARD8(&buffer, &SessionRunning) &&
        XdmcpReadCARD32(&buffer, &AliveSessionID)) {
        if (SessionRunning && AliveSessionID == SessionID) {
            state = XDM_RUN_SESSION;
            timeOutTime = GetTimeInMillis() + XDM_DEF_DORMANCY * 1000;
        }
        else {
            XdmcpDeadSession("Alive response indicates session dead");
        }
    }
}

_X_NORETURN
static void
XdmcpFatal(const char *type, ARRAY8Ptr status)
{
    FatalError("XDMCP fatal error: %s %*.*s\n", type,
               status->length, status->length, status->data);
}

static void
XdmcpWarning(const char *str)
{
    ErrorF("XDMCP warning: %s\n", str);
}

static void
get_addr_by_name(const char *argtype,
                 const char *namestr,
                 int port,
                 int socktype, SOCKADDR_TYPE * addr, SOCKLEN_TYPE * addrlen
#if defined(IPv6) && defined(AF_INET6)
                 , struct addrinfo **aip, struct addrinfo **aifirstp
#endif
    )
{
#if defined(IPv6) && defined(AF_INET6)
    struct addrinfo *ai;
    struct addrinfo hints;
    char portstr[6];
    char *pport = portstr;
    int gaierr;

    memset(&hints, 0, sizeof(hints));
    hints.ai_socktype = socktype;

    if (port == 0) {
        pport = NULL;
    }
    else if (port > 0 && port < 65535) {
        snprintf(portstr, sizeof(portstr), "%d", port);
    }
    else {
        FatalError("Xserver: port out of range: %d\n", port);
    }

    if (*aifirstp != NULL) {
        freeaddrinfo(*aifirstp);
        *aifirstp = NULL;
    }

    if ((gaierr = getaddrinfo(namestr, pport, &hints, aifirstp)) == 0) {
        for (ai = *aifirstp; ai != NULL; ai = ai->ai_next) {
            if (ai->ai_family == AF_INET || ai->ai_family == AF_INET6)
                break;
        }
        if ((ai == NULL) || (ai->ai_addrlen > sizeof(SOCKADDR_TYPE))) {
            FatalError("Xserver: %s host %s not on supported network type\n",
                       argtype, namestr);
        }
        else {
            *aip = ai;
            *addrlen = ai->ai_addrlen;
            memcpy(addr, ai->ai_addr, ai->ai_addrlen);
        }
    }
    else {
        FatalError("Xserver: %s: %s %s\n", gai_strerror(gaierr), argtype,
                   namestr);
    }
#else
    struct hostent *hep;

#ifdef XTHREADS_NEEDS_BYNAMEPARAMS
    _Xgethostbynameparams hparams;
#endif
#if defined(WIN32) && defined(TCPCONN)
    _XSERVTransWSAStartup();
#endif
    if (!(hep = _XGethostbyname(namestr, hparams))) {
        FatalError("Xserver: %s unknown host: %s\n", argtype, namestr);
    }
    if (hep->h_length == sizeof(struct in_addr)) {
        memmove(&addr->sin_addr, hep->h_addr, hep->h_length);
        *addrlen = sizeof(struct sockaddr_in);
        addr->sin_family = AF_INET;
        addr->sin_port = htons(port);
    }
    else {
        FatalError("Xserver: %s host on strange network %s\n", argtype,
                   namestr);
    }
#endif
}

static void
get_manager_by_name(int argc, char **argv, int i)
{

    if ((i + 1) == argc) {
        FatalError("Xserver: missing %s host name in command line\n", argv[i]);
    }

    get_addr_by_name(argv[i], argv[i + 1], xdm_udp_port, SOCK_DGRAM,
                     &ManagerAddress, &ManagerAddressLen
#if defined(IPv6) && defined(AF_INET6)
                     , &mgrAddr, &mgrAddrFirst
#endif
        );
}

static void
get_fromaddr_by_name(int argc, char **argv, int i)
{
#if defined(IPv6) && defined(AF_INET6)
    struct addrinfo *ai = NULL;
    struct addrinfo *aifirst = NULL;
#endif
    if (i == argc) {
        FatalError("Xserver: missing -from host name in command line\n");
    }
    get_addr_by_name("-from", argv[i], 0, 0, &FromAddress, &FromAddressLen
#if defined(IPv6) && defined(AF_INET6)
                     , &ai, &aifirst
#endif
        );
#if defined(IPv6) && defined(AF_INET6)
    if (aifirst != NULL)
        freeaddrinfo(aifirst);
#endif
    xdm_from = argv[i];
}

#if defined(IPv6) && defined(AF_INET6)
static int
get_mcast_options(int argc, char **argv, int i)
{
    const char *address = XDM_DEFAULT_MCAST_ADDR6;
    int hopcount = 1;
    struct addrinfo hints;
    char portstr[6];
    int gaierr;
    struct addrinfo *ai, *firstai;

    if ((i < argc) && (argv[i][0] != '-') && (argv[i][0] != '+')) {
        address = argv[i++];
        if ((i < argc) && (argv[i][0] != '-') && (argv[i][0] != '+')) {
            hopcount = strtol(argv[i++], NULL, 10);
            if ((hopcount < 1) || (hopcount > 255)) {
                FatalError("Xserver: multicast hop count out of range: %d\n",
                           hopcount);
            }
        }
    }

    if (xdm_udp_port > 0 && xdm_udp_port < 65535) {
        snprintf(portstr, sizeof(portstr), "%d", xdm_udp_port);
    }
    else {
        FatalError("Xserver: port out of range: %d\n", xdm_udp_port);
    }
    memset(&hints, 0, sizeof(hints));
    hints.ai_socktype = SOCK_DGRAM;

    if ((gaierr = getaddrinfo(address, portstr, &hints, &firstai)) == 0) {
        for (ai = firstai; ai != NULL; ai = ai->ai_next) {
            if (((ai->ai_family == AF_INET) &&
                 IN_MULTICAST(((struct sockaddr_in *) ai->ai_addr)
                              ->sin_addr.s_addr))
                || ((ai->ai_family == AF_INET6) &&
                    IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6 *) ai->ai_addr)
                                          ->sin6_addr)))
                break;
        }
        if (ai == NULL) {
            FatalError("Xserver: address not supported multicast type %s\n",
                       address);
        }
        else {
            struct multicastinfo *mcastinfo, *mcl;

            mcastinfo = malloc(sizeof(struct multicastinfo));
            mcastinfo->next = NULL;
            mcastinfo->ai = firstai;
            mcastinfo->hops = hopcount;

            if (mcastlist == NULL) {
                mcastlist = mcastinfo;
            }
            else {
                for (mcl = mcastlist; mcl->next != NULL; mcl = mcl->next) {
                    /* Do nothing  - just find end of list */
                }
                mcl->next = mcastinfo;
            }
        }
    }
    else {
        FatalError("Xserver: %s: %s\n", gai_strerror(gaierr), address);
    }
    return i;
}
#endif

#else
static int xdmcp_non_empty;     /* avoid complaint by ranlib */
#endif                          /* XDMCP */