Source to src/slirp/slirp.c


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#include "slirp.h"

/* host address */
struct in_addr our_addr;
/* host dns address */
struct in_addr dns_addr;
/* host loopback address */
struct in_addr loopback_addr;

/* address for slirp virtual addresses */
struct in_addr special_addr;
/* virtual address alias for host */
struct in_addr alias_addr;

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

uint8_t client_ethaddr[6];

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=NULL;
    ULONG    BufLen;
    DWORD    ret;
    IP_ADDR_STRING *pIPAddr;
    struct in_addr tmp_addr;
    
    FixedInfo = (FIXED_INFO *)GlobalAlloc(GPTR, sizeof(FIXED_INFO));
    BufLen = sizeof(FIXED_INFO);
   
    if (ERROR_BUFFER_OVERFLOW == GetNetworkParams(FixedInfo, &BufLen)) {
        if (FixedInfo) {
            GlobalFree(FixedInfo);
            FixedInfo = NULL;
        }
        FixedInfo = GlobalAlloc(GPTR, BufLen);
    }
	
    if ((ret = GetNetworkParams(FixedInfo, &BufLen)) != ERROR_SUCCESS) {
        printf("GetNetworkParams failed. ret = %08x\n", (u_int)ret );
        if (FixedInfo) {
            GlobalFree(FixedInfo);
            FixedInfo = NULL;
        }
        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
    if (FixedInfo) {
        GlobalFree(FixedInfo);
        FixedInfo = NULL;
    }
    return 0;
}

#else

static int get_dns_addr(struct in_addr *pdns_addr)
{
    char buff[512];
    char buff2[256+1];
    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 (tmp_addr.s_addr == loopback_addr.s_addr)
                tmp_addr = our_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

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

int slirp_init(void)
{
    //    debug_init("/tmp/slirp.log", DEBUG_DEFAULT);
    
#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);

    if (get_dns_addr(&dns_addr) < 0)
        return -1;

    inet_aton(CTL_SPECIAL, &special_addr);
	alias_addr.s_addr = special_addr.s_addr | htonl(CTL_ALIAS);
	getouraddr();
    return 0;
}

#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

int slirp_select_fill(int *pnfds, 
					  fd_set *readfds, fd_set *writefds, fd_set *xfds)
{
    struct socket *so, *so_next;
    int nfds;
    int timeout, 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) ||
			 (&ipq.ip_link != ipq.ip_link.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
	 */

	timeout = -1;

	/*
	 * If a slowtimo is needed, set timeout to 5ms from the last
	 * slow timeout. If a fast timeout is needed, set timeout within
	 * 2ms of when it was requested.
	 */
#	define SLOW_TIMO 5
#	define FAST_TIMO 2
	if (do_slowtimo) {
		timeout = (SLOW_TIMO - (curtime - last_slowtimo)) * 1000;
		if (timeout < 0)
		   timeout = 0;
		else if (timeout > (SLOW_TIMO * 1000))
		   timeout = SLOW_TIMO * 1000;
		
		/* Can only fasttimo if we also slowtimo */
		if (time_fasttimo) {
			tmp_time = (FAST_TIMO - (curtime - time_fasttimo)) * 1000;
			if (tmp_time < 0)
				tmp_time = 0;
			
			/* Choose the smallest of the 2 */
			if (tmp_time < timeout)
			   timeout = tmp_time;
		}
	}
	*pnfds = nfds;

	/*
	 * Adjust the timeout to make the minimum timeout
	 * 2ms (XXX?) to lessen the CPU load
	 */
	if (timeout < (FAST_TIMO * 1000))
		timeout = FAST_TIMO * 1000;

	return timeout;
}	

void slirp_select_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds)
{
	struct socket *so, *so_next;
	int ret;

	global_readfds = readfds;
	global_writefds = writefds;
	global_xfds = xfds;

	/* Update time */
	updtime();

	/*
	 * See if anything has timed out
	 */
	if (link_up) {
		if (time_fasttimo && ((curtime - time_fasttimo) >= FAST_TIMO)) {
			tcp_fasttimo();
			time_fasttimo = 0;
		}
		if (do_slowtimo && ((curtime - last_slowtimo) >= SLOW_TIMO)) {
			ip_slowtimo();
			tcp_slowtimo();
			last_slowtimo = curtime;
		}
	}

	/*
	 * Check sockets
	 */
	if (link_up) {
		/*
		 * Check TCP sockets
		 */
		for (so = tcb.so_next; so != &tcb; so = so_next) {
			so_next = so->so_next;

			/*
			 * FD_ISSET is meaningless on these sockets
			 * (and they can crash the program)
			 */
			if (so->so_state & SS_NOFDREF || so->s == -1)
				continue;

			/*
			 * Check for URG data
			 * This will soread as well, so no need to
			 * test for readfds below if this succeeds
			 */
			if (FD_ISSET(so->s, xfds))
				sorecvoob(so);
			/*
			 * Check sockets for reading
			 */
			else if (FD_ISSET(so->s, readfds)) {
				/*
				 * Check for incoming connections
				 */
				if (so->so_state & SS_FACCEPTCONN) {
					tcp_connect(so);
					continue;
				} /* else */
				ret = soread(so);

				/* Output it if we read something */
				if (ret > 0)
					tcp_output(sototcpcb(so));
			}

			/*
			 * Check sockets for writing
			 */
			if (FD_ISSET(so->s, writefds)) {
				/*
				 * Check for non-blocking, still-connecting sockets
				 */
				if (so->so_state & SS_ISFCONNECTING) {
					/* Connected */
					so->so_state &= ~SS_ISFCONNECTING;

					ret = send(so->s, (char*)&ret, 0, 0);
					if (ret < 0) {
						/* XXXXX Must fix, zero bytes is a NOP */
						int error = WSAGetLastError();
						if (error == EAGAIN || error == WSAEWOULDBLOCK ||
							error == WSAEINPROGRESS || error == WSAENOTCONN)
							continue;

						/* else failed */
						so->so_state = SS_NOFDREF;
					}
					/* else so->so_state &= ~SS_ISFCONNECTING; */

					/*
					 * Continue tcp_input
					 */
					tcp_input((struct mbuf *)NULL, sizeof(struct ip), so);
					/* continue; */
				}
				else
					ret = sowrite(so);
				/*
				 * XXXXX If we wrote something (a lot), there
				 * could be a need for a window update.
				 * In the worst case, the remote will send
				 * a window probe to get things going again
				 */
			}

			/*
			 * Probe a still-connecting, non-blocking socket
			 * to check if it's still alive
			 */
#ifdef PROBE_CONN
			if (so->so_state & SS_ISFCONNECTING) {
				ret = recv(so->s, (char *)&ret, 0, 0);

				if (ret < 0) {
					/* XXX */
					int error = WSAGetLastError();
					if (error == EAGAIN || error == WSAEWOULDBLOCK ||
						error == WSAEINPROGRESS || error == WSAENOTCONN)
						continue; /* Still connecting, continue */

					  /* else failed */
					so->so_state = SS_NOFDREF;

					/* tcp_input will take care of it */
				}
				else {
					ret = send(so->s, &ret, 0, 0);
					if (ret < 0) {
						/* XXX */
						int error = WSAGetLastError();
						if (error == EAGAIN || error == WSAEWOULDBLOCK ||
							error == WSAEINPROGRESS || error == WSAENOTCONN)
							continue;
						/* else failed */
						so->so_state = SS_NOFDREF;
					}
					else
						so->so_state &= ~SS_ISFCONNECTING;

				}
				tcp_input((struct mbuf *)NULL, sizeof(struct ip), so);
		} /* SS_ISFCONNECTING */
#endif
	}

		/*
		 * Now UDP sockets.
		 * Incoming packets are sent straight away, they're not buffered.
		 * Incoming UDP data isn't buffered either.
		 */
		for (so = udb.so_next; so != &udb; so = so_next) {
			so_next = so->so_next;

			if (so->s != -1 && FD_ISSET(so->s, readfds)) {
				sorecvfrom(so);
			}
		}
}

	/*
	 * See if we can start outputting
	 */
	if (if_queued && link_up)
		if_start();

	/* clear global file descriptor sets.
	 * these reside on the stack in vl.c
	 * so they're unusable if we're not in
	 * slirp_select_fill or slirp_select_poll.
	 */
	global_readfds = NULL;
	global_writefds = NULL;
	global_xfds = NULL;
}

#define ETH_ALEN 6
#define ETH_HLEN 14

#define ETH_P_IP	0x0800		/* Internet Protocol packet	*/
#define ETH_P_ARP	0x0806		/* Address Resolution packet	*/

#define	ARPOP_REQUEST	1		/* ARP request			*/
#define	ARPOP_REPLY	2		/* ARP reply			*/

struct ethhdr 
{
	unsigned char	h_dest[ETH_ALEN];	/* destination eth addr	*/
	unsigned char	h_source[ETH_ALEN];	/* source ether addr	*/
	unsigned short	h_proto;		/* packet type ID field	*/
};

struct arphdr
{
	unsigned short	ar_hrd;		/* format of hardware address	*/
	unsigned short	ar_pro;		/* format of protocol address	*/
	unsigned char	ar_hln;		/* length of hardware address	*/
	unsigned char	ar_pln;		/* length of protocol address	*/
	unsigned short	ar_op;		/* ARP opcode (command)		*/

	 /*
	  *	 Ethernet looks like this : This bit is variable sized however...
	  */
	unsigned char		ar_sha[ETH_ALEN];	/* sender hardware address	*/
	unsigned char		ar_sip[4];		/* sender IP address		*/
	unsigned char		ar_tha[ETH_ALEN];	/* target hardware address	*/
	unsigned char		ar_tip[4];		/* target IP address		*/
};

static void arp_input(const uint8_t *pkt, int pkt_len)
{
    const struct ethhdr *eh = (const struct ethhdr *)pkt;
    const struct arphdr *ah = (const struct arphdr *)(pkt + ETH_HLEN);
    uint8_t arp_reply[ETH_HLEN + sizeof(struct arphdr)];
    struct ethhdr *reh = (struct ethhdr *)arp_reply;
    struct arphdr *rah = (struct arphdr *)(arp_reply + ETH_HLEN);
    int ar_op;
    struct ex_list *ex_ptr;

    ar_op = ntohs(ah->ar_op);
    switch(ar_op) {
    case ARPOP_REQUEST:
        if (!memcmp(ah->ar_tip, &special_addr, 3)) {
            if (ah->ar_tip[3] == CTL_DNS || ah->ar_tip[3] == CTL_ALIAS) 
                goto arp_ok;
            for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
                if (ex_ptr->ex_addr == ah->ar_tip[3])
                    goto arp_ok;
            }
            return;
        arp_ok:
            /* XXX: make an ARP request to have the client address */
            memcpy(client_ethaddr, eh->h_source, ETH_ALEN);

            /* ARP request for alias/dns mac address */
            memcpy(reh->h_dest, pkt + ETH_ALEN, ETH_ALEN);
            memcpy(reh->h_source, special_ethaddr, ETH_ALEN - 1);
            reh->h_source[5] = ah->ar_tip[3];
            reh->h_proto = htons(ETH_P_ARP);

            rah->ar_hrd = htons(1);
            rah->ar_pro = htons(ETH_P_IP);
            rah->ar_hln = ETH_ALEN;
            rah->ar_pln = 4;
            rah->ar_op = htons(ARPOP_REPLY);
            memcpy(rah->ar_sha, reh->h_source, ETH_ALEN);
            memcpy(rah->ar_sip, ah->ar_tip, 4);
            memcpy(rah->ar_tha, ah->ar_sha, ETH_ALEN);
            memcpy(rah->ar_tip, ah->ar_sip, 4);
            slirp_output(arp_reply, sizeof(arp_reply));
        }
        break;
    default:
        break;
    }
}

void slirp_input(const uint8_t *pkt, int pkt_len)
{
    struct mbuf *m;
    int proto;

    if (pkt_len < ETH_HLEN)
        return;
    
    proto = (pkt[12] << 8) | pkt[13];
    switch(proto) {
    case ETH_P_ARP:
        arp_input(pkt, pkt_len);
        break;
    case ETH_P_IP:
        m = m_get();
        if (!m)
            return;
        /* Note: we add to align the IP header */
        m->m_len = pkt_len + 2;
        memcpy(m->m_data + 2, pkt, pkt_len);

        m->m_data += 2 + ETH_HLEN;
        m->m_len -= 2 + ETH_HLEN;

        ip_input(m);
        break;
    default:
        break;
    }
}

/* output the IP packet to the ethernet device */
void if_encap(const uint8_t *ip_data, int ip_data_len)
{
    uint8_t buf[1600];
    struct ethhdr *eh = (struct ethhdr *)buf;

    if (ip_data_len + ETH_HLEN > sizeof(buf))
        return;

    memcpy(eh->h_dest, client_ethaddr, ETH_ALEN);
    memcpy(eh->h_source, special_ethaddr, ETH_ALEN - 1);
    /* XXX: not correct */
    eh->h_source[5] = CTL_ALIAS;
    eh->h_proto = htons(ETH_P_IP);
    memcpy(buf + sizeof(struct ethhdr), ip_data, ip_data_len);
    slirp_output(buf, ip_data_len + ETH_HLEN);
}

int slirp_redir(int is_udp, int host_port, 
                struct in_addr guest_addr, int guest_port)
{
    if (is_udp) {
        if (!udp_listen(htons(host_port), guest_addr.s_addr, 
                        htons(guest_port), 0))
            return -1;
    } else {
        if (!solisten(htons(host_port), guest_addr.s_addr, 
                      htons(guest_port), 0))
            return -1;
    }
    return 0;
}

int slirp_add_exec(int do_pty, const char *args, int addr_low_byte, 
                  int guest_port)
{
    return add_exec(&exec_list, do_pty, args, 
                    addr_low_byte, htons(guest_port));
}