zinternal.c

Linux下的多协议即时通讯程序源代码

/* This file is part of the Project Athena Zephyr Notification System.
 * It contains source for the internal Zephyr routines.
 *
 *	Created by:	Robert French
 *
 *	Copyright (c) 1987,1988,1991 by the Massachusetts Institute of
 *	Technology.
 *	For copying and distribution information, see the file
 *	"mit-copyright.h". 
 */

#include "internal.h"
#ifdef WIN32
#include <winsock2.h>

#ifndef ZEPHYR_USES_KERBEROS
   int gettimeofday(struct timeval* p, struct timezone* tz ){
     union {
       long long ns100; /*time since 1 Jan 1601 in 100ns units */
       FILETIME ft;
     } _now;

     GetSystemTimeAsFileTime( &(_now.ft) );
     p->tv_usec=(long)((_now.ns100 / 10LL) % 1000000LL );
     p->tv_sec= (long)((_now.ns100-(116444736000000000LL))/10000000LL);
     return 0;
   }
#endif 

#else
#include <arpa/inet.h>
#include <sys/socket.h>
#include <utmp.h>
#endif

extern char *inet_ntoa ();

int __Zephyr_fd = -1;
int __Zephyr_open;
int __Zephyr_port = -1;
struct in_addr __My_addr;
int __Q_CompleteLength;
int __Q_Size;
struct _Z_InputQ *__Q_Head, *__Q_Tail;
struct sockaddr_in __HM_addr;
struct sockaddr_in __HM_addr_real;
int __HM_set;
int __Zephyr_server;
ZLocations_t *__locate_list;
int __locate_num;
int __locate_next;
ZSubscription_t *__subscriptions_list;
int __subscriptions_num;
int __subscriptions_next;
int Z_discarded_packets = 0;

#ifdef ZEPHYR_USES_KERBEROS
C_Block __Zephyr_session;
#endif
char __Zephyr_realm[REALM_SZ];

#ifdef Z_DEBUG
void (*__Z_debug_print) __P((const char *fmt, va_list args, void *closure));
void *__Z_debug_print_closure;
#endif

#define min(a,b) ((a)<(b)?(a):(b))

static int Z_AddField __P((char **ptr, const char *field, char *end));
static int find_or_insert_uid __P((ZUnique_Id_t *uid, ZNotice_Kind_t kind));

/* Find or insert uid in the old uids buffer.  The buffer is a sorted
 * circular queue.  We make the assumption that most packets arrive in
 * order, so we can usually search for a uid or insert it into the buffer
 * by looking back just a few entries from the end.  Since this code is
 * only executed by the client, the implementation isn't microoptimized. */
static int find_or_insert_uid(uid, kind)
    ZUnique_Id_t *uid;
    ZNotice_Kind_t kind;
{
    static struct _filter {
	ZUnique_Id_t	uid;
	ZNotice_Kind_t	kind;
	time_t		t;
    } *buffer;
    static long size;
    static long start;
    static long num;

    time_t now;
    struct _filter *new;
    long i, j, new_size;
    int result;

    /* Initialize the uid buffer if it hasn't been done already. */
    if (!buffer) {
	size = Z_INITFILTERSIZE;
	buffer = (struct _filter *) malloc(size * sizeof(*buffer));
	if (!buffer)
	    return 0;
    }

    /* Age the uid buffer, discarding any uids older than the clock skew. */
    time(&now);
    while (num && (now - buffer[start % size].t) > CLOCK_SKEW)
	start++, num--;
    start %= size;

    /* Make room for a new uid, since we'll probably have to insert one. */
    if (num == size) {
	new_size = size * 2 + 2;
	new = (struct _filter *) malloc(new_size * sizeof(*new));
	if (!new)
	    return 0;
	for (i = 0; i < num; i++)
	    new[i] = buffer[(start + i) % size];
	free(buffer);
	buffer = new;
	size = new_size;
	start = 0;
    }

    /* Search for this uid in the buffer, starting from the end. */
    for (i = start + num - 1; i >= start; i--) {
	result = memcmp(uid, &buffer[i % size].uid, sizeof(*uid));
	if (result == 0 && buffer[i % size].kind == kind)
	    return 1;
	if (result > 0)
	    break;
    }

    /* We didn't find it; insert the uid into the buffer after i. */
    i++;
    for (j = start + num; j > i; j--)
	buffer[j % size] = buffer[(j - 1) % size];
    buffer[i % size].uid = *uid;
    buffer[i % size].kind = kind;
    buffer[i % size].t = now;
    num++;

    return 0;
}


/* Return 1 if there is a packet waiting, 0 otherwise */

static int Z_PacketWaiting()
{
    struct timeval tv;
    fd_set read;

    tv.tv_sec = tv.tv_usec = 0;
    FD_ZERO(&read);
    FD_SET(ZGetFD(), &read);
    return (select(ZGetFD() + 1, &read, NULL, NULL, &tv));
} 


/* Wait for a complete notice to become available */

Code_t Z_WaitForComplete()
{
    Code_t retval;

    if (__Q_CompleteLength)
	return (Z_ReadEnqueue());

    while (!__Q_CompleteLength)
	if ((retval = Z_ReadWait()) != ZERR_NONE)
	    return (retval);

    return (ZERR_NONE);
}


/* Read any available packets and enqueue them */

Code_t Z_ReadEnqueue()
{
    Code_t retval;

    if (ZGetFD() < 0)
	return (ZERR_NOPORT);
    
    while (Z_PacketWaiting())
	if ((retval = Z_ReadWait()) != ZERR_NONE)
	    return (retval);

    return (ZERR_NONE);
}


/*
 * Search the queue for a notice with the proper multiuid - remove any
 * notices that haven't been touched in a while
 */

static struct _Z_InputQ *Z_SearchQueue(uid, kind)
    ZUnique_Id_t *uid;
    ZNotice_Kind_t kind;
{
    register struct _Z_InputQ *qptr;
    struct _Z_InputQ *next;
    struct timeval tv;

    (void) gettimeofday(&tv, (struct timezone *)0);

    qptr = __Q_Head;

    while (qptr) {
	if (ZCompareUID(uid, &qptr->uid) && qptr->kind == kind)
	    return (qptr);
	next = qptr->next;
	if (qptr->timep && (qptr->timep+Z_NOTICETIMELIMIT < tv.tv_sec))
	    Z_RemQueue(qptr);
	qptr = next;
    }
    return (NULL);
}

/*
 * Now we delve into really convoluted queue handling and
 * fragmentation reassembly algorithms and other stuff you probably
 * don't want to look at...
 *
 * This routine does NOT guarantee a complete packet will be ready when it
 * returns.
 */

Code_t Z_ReadWait()
{
    register struct _Z_InputQ *qptr;
    ZNotice_t notice;
    ZPacket_t packet;
    struct sockaddr_in olddest, from;
    int packet_len, zvlen, part, partof;
    socklen_t from_len;
    char *slash;
    Code_t retval;
    fd_set fds;
    struct timeval tv;

    if (ZGetFD() < 0)
	return (ZERR_NOPORT);
	
    FD_ZERO(&fds);
    FD_SET(ZGetFD(), &fds);
    tv.tv_sec = 60;
    tv.tv_usec = 0;

    if (select(ZGetFD() + 1, &fds, NULL, NULL, &tv) < 0)
      return (errno);
    if (!FD_ISSET(ZGetFD(), &fds))
      return ETIMEDOUT;

    from_len = sizeof(struct sockaddr_in);

    packet_len = recvfrom(ZGetFD(), packet, sizeof(packet), 0, 
			  (struct sockaddr *)&from, &from_len);

    if (packet_len < 0)
	return (errno);

    if (!packet_len)
	return (ZERR_EOF);

    /* Ignore obviously non-Zephyr packets. */
    zvlen = sizeof(ZVERSIONHDR) - 1;
    if (packet_len < zvlen || memcmp(packet, ZVERSIONHDR, zvlen) != 0) {
	Z_discarded_packets++;
	return (ZERR_NONE);
    }	

    /* Parse the notice */
    if ((retval = ZParseNotice(packet, packet_len, &notice)) != ZERR_NONE)
	return (retval);

    /*
     * If we're not a server and the notice is of an appropriate kind,
     * send back a CLIENTACK to whoever sent it to say we got it.
     */
    if (!__Zephyr_server) {
	if (notice.z_kind != HMACK && notice.z_kind != SERVACK &&
	    notice.z_kind != SERVNAK && notice.z_kind != CLIENTACK) {
	    ZNotice_t tmpnotice;
	    ZPacket_t pkt;
	    int len;

	    tmpnotice = notice;
	    tmpnotice.z_kind = CLIENTACK;
	    tmpnotice.z_message_len = 0;
	    olddest = __HM_addr;
	    __HM_addr = from;
	    if ((retval = ZFormatSmallRawNotice(&tmpnotice, pkt, &len))
		!= ZERR_NONE)
		return(retval);
	    if ((retval = ZSendPacket(pkt, len, 0)) != ZERR_NONE)
		return (retval);
	    __HM_addr = olddest;
	}
	if (find_or_insert_uid(&notice.z_uid, notice.z_kind))
	    return(ZERR_NONE);

	/* Check authentication on the notice. */
	notice.z_checked_auth = ZCheckAuthentication(&notice, &from);
    }


    /*
     * Parse apart the z_multinotice field - if the field is blank for
     * some reason, assume this packet stands by itself.
     */
    slash = strchr(notice.z_multinotice, '/');
    if (slash) {
	part = atoi(notice.z_multinotice);
	partof = atoi(slash+1);
	if (part > partof || partof == 0) {
	    part = 0;
	    partof = notice.z_message_len;
	}
    }
    else {
	part = 0;
	partof = notice.z_message_len;
    }

    /* Too big a packet...just ignore it! */
    if (partof > Z_MAXNOTICESIZE)
	return (ZERR_NONE);

    /*
     * If we aren't a server and we can find a notice in the queue
     * with the same multiuid field, insert the current fragment as
     * appropriate.
     */
    switch (notice.z_kind) {
    case SERVACK:
    case SERVNAK:
	/* The SERVACK and SERVNAK replies shouldn't be reassembled
	   (they have no parts).  Instead, we should hold on to the reply
	   ONLY if it's the first part of a fragmented message, i.e.
	   multi_uid == uid.  This allows programs to wait for the uid
	   of the first packet, and get a response when that notice
	   arrives.  Acknowledgements of the other fragments are discarded
	   (XXX we assume here that they all carry the same information
	   regarding failure/success)
	 */
	if (!__Zephyr_server &&
	    !ZCompareUID(&notice.z_multiuid, &notice.z_uid))
	    /* they're not the same... throw away this packet. */
	    return(ZERR_NONE);
	/* fall thru & process it */
    default:
	/* for HMACK types, we assume no packet loss (local loopback
	   connections).  The other types can be fragmented and MUST
	   run through this code. */
	if (!__Zephyr_server && (qptr = Z_SearchQueue(&notice.z_multiuid,
						      notice.z_kind))) {
	    /*
	     * If this is the first fragment, and we haven't already
	     * gotten a first fragment, grab the header from it.
	     */
	    if (part == 0 && !qptr->header) {
		qptr->header_len = packet_len-notice.z_message_len;
		qptr->header = (char *) malloc((unsigned) qptr->header_len);
		if (!qptr->header)
		    return (ENOMEM);
		(void) memcpy(qptr->header, packet, qptr->header_len);
	    }
	    return (Z_AddNoticeToEntry(qptr, &notice, part));
	}
    }

    /*
     * We'll have to create a new entry...make sure the queue isn't
     * going to get too big.
     */
    if (__Q_Size+(__Zephyr_server ? notice.z_message_len : partof) > Z_MAXQUEUESIZE)
	return (ZERR_NONE);

    /*
     * This is a notice we haven't heard of, so create a new queue
     * entry for it and zero it out.
     */
    qptr = (struct _Z_InputQ *)malloc(sizeof(struct _Z_InputQ));
    if (!qptr)
	return (ENOMEM);
    (void) memset((char *)qptr, 0, sizeof(struct _Z_InputQ));

    /* Insert the entry at the end of the queue */
    qptr->next = NULL;
    qptr->prev = __Q_Tail;
    if (__Q_Tail)
	__Q_Tail->next = qptr;
    __Q_Tail = qptr;

    if (!__Q_Head)
	__Q_Head = qptr;

    
    /* Copy the from field, multiuid, kind, and checked authentication. */
    qptr->from = from;
    qptr->uid = notice.z_multiuid;
    qptr->kind = notice.z_kind;
    qptr->auth = notice.z_checked_auth;
    
    /*
     * If this is the first part of the notice, we take the header
     * from it.  We only take it if this is the first fragment so that
     * the Unique ID's will be predictable.
     *
     * If a Zephyr Server, we always take the header.
     */
    if (__Zephyr_server || part == 0) {
	qptr->header_len = packet_len-notice.z_message_len;
	qptr->header = (char *) malloc((unsigned) qptr->header_len);
	if (!qptr->header)
	    return ENOMEM;
	(void) memcpy(qptr->header, packet, qptr->header_len);
    }

    /*
     * If this is not a fragmented notice, then don't bother with a
     * hole list.
     * If we are a Zephyr server, all notices are treated as complete.
     */
    if (__Zephyr_server || (part == 0 && notice.z_message_len == partof)) {
	__Q_CompleteLength++;
	qptr->holelist = (struct _Z_Hole *) 0;
	qptr->complete = 1;
	/* allocate a msg buf for this piece */
	if (notice.z_message_len == 0)
	    qptr->msg = 0;
	else if (!(qptr->msg = (char *) malloc((unsigned) notice.z_message_len)))
	    return(ENOMEM);
	else
	    (void) memcpy(qptr->msg, notice.z_message, notice.z_message_len);
	qptr->msg_len = notice.z_message_len;
	__Q_Size += notice.z_message_len;
	qptr->packet_len = qptr->header_len+qptr->msg_len;
	if (!(qptr->packet = (char *) malloc((unsigned) qptr->packet_len)))
	    return (ENOMEM);
	(void) memcpy(qptr->packet, qptr->header, qptr->header_len);
	if(qptr->msg)
	    (void) memcpy(qptr->packet+qptr->header_len, qptr->msg,
			   qptr->msg_len);
	return (ZERR_NONE);
    }

    /*
     * We know how long the message is going to be (this is better
     * than IP fragmentation...), so go ahead and allocate it all.
     */
    if (!(qptr->msg = (char *) malloc((unsigned) partof)) && partof)
	return (ENOMEM);
    qptr->msg_len = partof;
    __Q_Size += partof;

    /*
     * Well, it's a fragmented notice...allocate a hole list and
     * initialize it to the full packet size.  Then insert the
     * current fragment.
     */
    if (!(qptr->holelist = (struct _Z_Hole *)
	  malloc(sizeof(struct _Z_Hole))))
	return (ENOMEM);
    qptr->holelist->next = (struct _Z_Hole *) 0;
    qptr->holelist->first = 0;
    qptr->holelist->last = partof-1;
    return (Z_AddNoticeToEntry(qptr, &notice, part));
}


/* Fragment management routines - compliments, more or less, of RFC815 */

Code_t Z_AddNoticeToEntry(qptr, notice, part)
    struct _Z_InputQ *qptr;
    ZNotice_t *notice;
    int part;
{
    int last, oldfirst, oldlast;
    struct _Z_Hole *hole, *lasthole;
    struct timeval tv;

    /* Incorporate this notice's checked authentication. */
    if (notice->z_checked_auth == ZAUTH_FAILED)
	qptr->auth = ZAUTH_FAILED;
    else if (notice->z_checked_auth == ZAUTH_NO && qptr->auth != ZAUTH_FAILED)
	qptr->auth = ZAUTH_NO;

    (void) gettimeofday(&tv, (struct timezone *)0);
    qptr->timep = tv.tv_sec;
    
    last = part+notice->z_message_len-1;

    hole = qptr->holelist;
    lasthole = (struct _Z_Hole *) 0;