slirp.c

一个Windows下的Linux专用虚拟机

#include "slirp.h"

#if 0
/* host address */
struct in_addr our_addr;
#endif
/* host dns address */
static struct in_addr dns_addr;
/* host loopback address */
struct in_addr loopback_addr;	/* 127.0.0.1 */

/* address for slirp virtual addresses */
struct in_addr special_addr;	/* 10.0.2.0 */
/* virtual address alias for host */
struct in_addr alias_addr;	/* 10.0.2.2  windows */
struct in_addr client_addr;	/* 10.0.2.15 Linux */

const uint8_t special_ethaddr[6] = { 
    0x52, 0x54, 0x00, 0x12, 0x35, 0x00
};

uint8_t client_ethaddr[6] = { 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};

const uint8_t bcast_ethaddr[6] = { 
    0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};

int do_slowtimo;
int link_up;
struct timeval tt;
FILE *lfd;
struct ex_list *exec_list;

/* XXX: suppress those select globals */
fd_set *global_readfds, *global_writefds, *global_xfds;

char slirp_hostname[33];

#ifdef _WIN32

static int get_dns_addr(struct in_addr *pdns_addr)
{
    FIXED_INFO *FixedInfo;
    ULONG    BufLen;
    DWORD    ret;
    IP_ADDR_STRING *pIPAddr;
    struct in_addr tmp_addr;
    
    FixedInfo = (FIXED_INFO *)GlobalAlloc(GPTR, sizeof(FIXED_INFO));
    if (!FixedInfo)
	return -1;

    BufLen = sizeof(FIXED_INFO);
   
    if (ERROR_BUFFER_OVERFLOW == GetNetworkParams(FixedInfo, &BufLen)) {
        GlobalFree(FixedInfo);
        FixedInfo = GlobalAlloc(GPTR, BufLen);
	if (!FixedInfo)
	    return -1;
    }
	
    if ((ret = GetNetworkParams(FixedInfo, &BufLen)) != ERROR_SUCCESS) {
        printf("GetNetworkParams failed. ret = %08x\n", (u_int)ret );
        GlobalFree(FixedInfo);
        return -1;
    }
     
    pIPAddr = &(FixedInfo->DnsServerList);
    inet_aton(pIPAddr->IpAddress.String, &tmp_addr);
    *pdns_addr = tmp_addr;
#if 0
    printf( "DNS Servers:\n" );
    printf( "DNS Addr:%s\n", pIPAddr->IpAddress.String );
    
    pIPAddr = FixedInfo -> DnsServerList.Next;
    while ( pIPAddr ) {
            printf( "DNS Addr:%s\n", pIPAddr ->IpAddress.String );
            pIPAddr = pIPAddr ->Next;
    }
#endif
    GlobalFree(FixedInfo);
    return 0;
}

#else

static int get_dns_addr(struct in_addr *pdns_addr)
{
    char buff[512];
    char buff2[256];
    FILE *f;
    int found = 0;
    struct in_addr tmp_addr;
    
    f = fopen("/etc/resolv.conf", "r");
    if (!f)
        return -1;

    lprint("IP address of your DNS(s): ");
    while (fgets(buff, 512, f) != NULL) {
        if (sscanf(buff, "nameserver%*[ \t]%256s", buff2) == 1) {
            if (!inet_aton(buff2, &tmp_addr))
                continue;
            if (is_localhost(tmp_addr))
                tmp_addr = alias_addr;
            /* If it's the first one, set it to dns_addr */
            if (!found)
                *pdns_addr = tmp_addr;
            else
                lprint(", ");
            if (++found > 3) {
                lprint("(more)");
                break;
            } else
                lprint("%s", inet_ntoa(tmp_addr));
        }
    }
    fclose(f);
    if (!found)
        return -1;
    return 0;
}

#endif

/* Get DNS-Address from host, cached for 10 Seconds (SO_EXPIREFAST) */
struct in_addr cached_dns_addr (void)
{
    static long dns_expire;
    
    if (!dns_addr.s_addr || curtime > dns_expire) {
        if (get_dns_addr(&dns_addr) < 0) {
            fprintf(stderr, "Could not get DNS address\n");
            return (dns_addr);
        }

        dns_expire = curtime + SO_EXPIREFAST;
    }
    return (dns_addr);
}

#ifdef _WIN32
static void slirp_cleanup(void)
{
    WSACleanup();
}
#endif

void slirp_init(void)
{
#ifdef DEBUG
    debug_init("slirp.log", DEBUG_DEFAULT);
#endif
    
#ifdef _WIN32
    {
        WSADATA Data;
        WSAStartup(MAKEWORD(2,0), &Data);
	atexit(slirp_cleanup);
    }
#endif

    link_up = 1;

    if_init();
    ip_init();

    /* Initialise mbufs *after* setting the MTU */
    m_init();

    /* set default addresses */
    inet_aton("127.0.0.1", &loopback_addr);

    inet_aton(CTL_SPECIAL, &special_addr);
    alias_addr.s_addr = special_addr.s_addr | htonl(CTL_ALIAS);
    client_addr.s_addr = special_addr.s_addr | htonl(CTL_CLIENT);
#if 0
    getouraddr();
#endif
}

#define CONN_CANFSEND(so) (((so)->so_state & (SS_FCANTSENDMORE|SS_ISFCONNECTED)) == SS_ISFCONNECTED)
#define CONN_CANFRCV(so) (((so)->so_state & (SS_FCANTRCVMORE|SS_ISFCONNECTED)) == SS_ISFCONNECTED)
#define UPD_NFDS(x) if (nfds < (x)) nfds = (x)

/*
 * curtime kept to an accuracy of 1ms
 */
#ifdef _WIN32
static void updtime(void)
{
    struct _timeb tb;

    _ftime(&tb);
    curtime = (u_int)tb.time * (u_int)1000;
    curtime += (u_int)tb.millitm;
}
#else
static void updtime(void)
{
	gettimeofday(&tt, 0);
	
	curtime = (u_int)tt.tv_sec * (u_int)1000;
	curtime += (u_int)tt.tv_usec / (u_int)1000;
	
	if ((tt.tv_usec % 1000) >= 500)
	   curtime++;
}
#endif

void slirp_select_fill(int *pnfds, 
                       fd_set *readfds, fd_set *writefds, fd_set *xfds)
{
    struct socket *so, *so_next;
    struct timeval timeout;
    int nfds;
    int tmp_time;

    /* fail safe */
    global_readfds = NULL;
    global_writefds = NULL;
    global_xfds = NULL;
    
    nfds = *pnfds;
	/*
	 * First, TCP sockets
	 */
	do_slowtimo = 0;
	if (link_up) {
		/* 
		 * *_slowtimo needs calling if there are IP fragments
		 * in the fragment queue, or there are TCP connections active
		 */
		do_slowtimo = ((tcb.so_next != &tcb) ||
			       ((struct ipasfrag *)&ipq != (struct ipasfrag *)ipq.next));
		
		for (so = tcb.so_next; so != &tcb; so = so_next) {
			so_next = so->so_next;
			
			/*
			 * See if we need a tcp_fasttimo
			 */
			if (time_fasttimo == 0 && so->so_tcpcb->t_flags & TF_DELACK)
			   time_fasttimo = curtime; /* Flag when we want a fasttimo */
			
			/*
			 * NOFDREF can include still connecting to local-host,
			 * newly socreated() sockets etc. Don't want to select these.
	 		 */
			if (so->so_state & SS_NOFDREF || so->s == -1)
			   continue;
			
			/*
			 * Set for reading sockets which are accepting
			 */
			if (so->so_state & SS_FACCEPTCONN) {
                                FD_SET(so->s, readfds);
				UPD_NFDS(so->s);
				continue;
			}
			
			/*
			 * Set for writing sockets which are connecting
			 */
			if (so->so_state & SS_ISFCONNECTING) {
				FD_SET(so->s, writefds);
				UPD_NFDS(so->s);
				continue;
			}
			
			/*
			 * Set for writing if we are connected, can send more, and
			 * we have something to send
			 */
			if (CONN_CANFSEND(so) && so->so_rcv.sb_cc) {
				FD_SET(so->s, writefds);
				UPD_NFDS(so->s);
			}
			
			/*
			 * Set for reading (and urgent data) if we are connected, can
			 * receive more, and we have room for it XXX /2 ?
			 */
			if (CONN_CANFRCV(so) && (so->so_snd.sb_cc < (so->so_snd.sb_datalen/2))) {
				FD_SET(so->s, readfds);
				FD_SET(so->s, xfds);
				UPD_NFDS(so->s);
			}
		}
		
		/*
		 * UDP sockets
		 */
		for (so = udb.so_next; so != &udb; so = so_next) {
			so_next = so->so_next;
			
			/*
			 * See if it's timed out
			 */
			if (so->so_expire) {
				if (so->so_expire <= curtime) {
					udp_detach(so);
					continue;
				} else
					do_slowtimo = 1; /* Let socket expire */
			}
			
			/*
			 * When UDP packets are received from over the
			 * link, they're sendto()'d straight away, so
			 * no need for setting for writing
			 * Limit the number of packets queued by this session
			 * to 4.  Note that even though we try and limit this
			 * to 4 packets, the session could have more queued
			 * if the packets needed to be fragmented
			 * (XXX <= 4 ?)
			 */
			if ((so->so_state & SS_ISFCONNECTED) && so->so_queued <= 4) {
				FD_SET(so->s, readfds);
				UPD_NFDS(so->s);
			}
		}
	}
	
	/*
	 * Setup timeout to use minimum CPU usage, especially when idle
	 */
	
	/* 
	 * First, see the timeout needed by *timo
	 */
	timeout.tv_sec = 0;
	timeout.tv_usec = -1;
	/*
	 * If a slowtimo is needed, set timeout to 500ms from the last
	 * slow timeout. If a fast timeout is needed, set timeout within
	 * 200ms of when it was requested.
	 */
	if (do_slowtimo) {
		/* XXX + 10000 because some select()'s aren't that accurate */
		timeout.tv_usec = ((500 - (curtime - last_slowtimo)) * 1000) + 10000;
		if (timeout.tv_usec < 0)
		   timeout.tv_usec = 0;
		else if (timeout.tv_usec > 510000)
		   timeout.tv_usec = 510000;
		
		/* Can only fasttimo if we also slowtimo */
		if (time_fasttimo) {
			tmp_time = (200 - (curtime - time_fasttimo)) * 1000;
			if (tmp_time < 0)
			   tmp_time = 0;
			
			/* Choose the smallest of the 2 */
			if (tmp_time < timeout.tv_usec)
			   timeout.tv_usec = (u_int)tmp_time;