initial user mode network support

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@733 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 1325 insertions, 0 deletions

diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
new file mode 100644
index 000000000..bf8a2026f
--- /dev/null
+++ b/slirp/tcp_subr.c
@@ -0,0 +1,1325 @@
+/*
+ * Copyright (c) 1982, 1986, 1988, 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)tcp_subr.c	8.1 (Berkeley) 6/10/93
+ * tcp_subr.c,v 1.5 1994/10/08 22:39:58 phk Exp
+ */
+
+/*
+ * Changes and additions relating to SLiRP
+ * Copyright (c) 1995 Danny Gasparovski.
+ * 
+ * Please read the file COPYRIGHT for the 
+ * terms and conditions of the copyright.
+ */
+
+#define WANT_SYS_IOCTL_H
+#include <slirp.h>
+
+/* patchable/settable parameters for tcp */
+int 	tcp_mssdflt = TCP_MSS;
+int 	tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
+int	tcp_do_rfc1323 = 0;	/* Don't do rfc1323 performance enhancements */
+int	tcp_rcvspace;	/* You may want to change this */
+int	tcp_sndspace;	/* Keep small if you have an error prone link */
+
+/*
+ * Tcp initialization
+ */
+void
+tcp_init()
+{
+	tcp_iss = 1;		/* wrong */
+	tcb.so_next = tcb.so_prev = &tcb;
+	
+	/* tcp_rcvspace = our Window we advertise to the remote */
+	tcp_rcvspace = TCP_RCVSPACE;
+	tcp_sndspace = TCP_SNDSPACE;
+	
+	/* Make sure tcp_sndspace is at least 2*MSS */
+	if (tcp_sndspace < 2*(min(if_mtu, if_mru) - sizeof(struct tcpiphdr)))
+		tcp_sndspace = 2*(min(if_mtu, if_mru) - sizeof(struct tcpiphdr));
+}
+
+/*
+ * Create template to be used to send tcp packets on a connection.
+ * Call after host entry created, fills
+ * in a skeletal tcp/ip header, minimizing the amount of work
+ * necessary when the connection is used.
+ */
+/* struct tcpiphdr * */
+void
+tcp_template(tp)
+	struct tcpcb *tp;
+{
+	struct socket *so = tp->t_socket;
+	register struct tcpiphdr *n = &tp->t_template;
+
+	n->ti_next = n->ti_prev = 0;
+	n->ti_x1 = 0;
+	n->ti_pr = IPPROTO_TCP;
+	n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
+	n->ti_src = so->so_faddr;
+	n->ti_dst = so->so_laddr;
+	n->ti_sport = so->so_fport;
+	n->ti_dport = so->so_lport;
+	
+	n->ti_seq = 0;
+	n->ti_ack = 0;
+	n->ti_x2 = 0;
+	n->ti_off = 5;
+	n->ti_flags = 0;
+	n->ti_win = 0;
+	n->ti_sum = 0;
+	n->ti_urp = 0;
+}
+
+/*
+ * Send a single message to the TCP at address specified by
+ * the given TCP/IP header.  If m == 0, then we make a copy
+ * of the tcpiphdr at ti and send directly to the addressed host.
+ * This is used to force keep alive messages out using the TCP
+ * template for a connection tp->t_template.  If flags are given
+ * then we send a message back to the TCP which originated the
+ * segment ti, and discard the mbuf containing it and any other
+ * attached mbufs.
+ *
+ * In any case the ack and sequence number of the transmitted
+ * segment are as specified by the parameters.
+ */
+void
+tcp_respond(tp, ti, m, ack, seq, flags)
+	struct tcpcb *tp;
+	register struct tcpiphdr *ti;
+	register struct mbuf *m;
+	tcp_seq ack, seq;
+	int flags;
+{
+	register int tlen;
+	int win = 0;
+
+	DEBUG_CALL("tcp_respond");
+	DEBUG_ARG("tp = %lx", (long)tp);
+	DEBUG_ARG("ti = %lx", (long)ti);
+	DEBUG_ARG("m = %lx", (long)m);
+	DEBUG_ARG("ack = %u", ack);
+	DEBUG_ARG("seq = %u", seq);
+	DEBUG_ARG("flags = %x", flags);
+	
+	if (tp)
+		win = sbspace(&tp->t_socket->so_rcv);
+	if (m == 0) {
+		if ((m = m_get()) == NULL)
+			return;
+#ifdef TCP_COMPAT_42
+		tlen = 1;
+#else
+		tlen = 0;
+#endif
+		m->m_data += if_maxlinkhdr;
+		*mtod(m, struct tcpiphdr *) = *ti;
+		ti = mtod(m, struct tcpiphdr *);
+		flags = TH_ACK;
+	} else {
+		/* 
+		 * ti points into m so the next line is just making
+		 * the mbuf point to ti
+		 */
+		m->m_data = (caddr_t)ti;
+		
+		m->m_len = sizeof (struct tcpiphdr);
+		tlen = 0;
+#define xchg(a,b,type) { type t; t=a; a=b; b=t; }
+		xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);
+		xchg(ti->ti_dport, ti->ti_sport, u_int16_t);
+#undef xchg
+	}
+	ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
+	tlen += sizeof (struct tcpiphdr);
+	m->m_len = tlen;
+
+	ti->ti_next = ti->ti_prev = 0;
+	ti->ti_x1 = 0;
+	ti->ti_seq = htonl(seq);
+	ti->ti_ack = htonl(ack);
+	ti->ti_x2 = 0;
+	ti->ti_off = sizeof (struct tcphdr) >> 2;
+	ti->ti_flags = flags;
+	if (tp)
+		ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale));
+	else
+		ti->ti_win = htons((u_int16_t)win);
+	ti->ti_urp = 0;
+	ti->ti_sum = 0;
+	ti->ti_sum = cksum(m, tlen);
+	((struct ip *)ti)->ip_len = tlen;
+
+	if(flags & TH_RST) 
+	  ((struct ip *)ti)->ip_ttl = MAXTTL;
+	else 
+	  ((struct ip *)ti)->ip_ttl = ip_defttl;
+	
+	(void) ip_output((struct socket *)0, m);
+}
+
+/*
+ * Create a new TCP control block, making an
+ * empty reassembly queue and hooking it to the argument
+ * protocol control block.
+ */
+struct tcpcb *
+tcp_newtcpcb(so)
+	struct socket *so;
+{
+	register struct tcpcb *tp;
+	
+	tp = (struct tcpcb *)malloc(sizeof(*tp));
+	if (tp == NULL)
+		return ((struct tcpcb *)0);
+	
+	memset((char *) tp, 0, sizeof(struct tcpcb));
+	tp->seg_next = tp->seg_prev = (tcpiphdrp_32)tp;
+	tp->t_maxseg = tcp_mssdflt;
+	
+	tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
+	tp->t_socket = so;
+	
+	/*
+	 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
+	 * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives
+	 * reasonable initial retransmit time.
+	 */
+	tp->t_srtt = TCPTV_SRTTBASE;
+	tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << 2;
+	tp->t_rttmin = TCPTV_MIN;
+
+	TCPT_RANGESET(tp->t_rxtcur, 
+	    ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,
+	    TCPTV_MIN, TCPTV_REXMTMAX);
+
+	tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
+	tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
+	tp->t_state = TCPS_CLOSED;
+	
+	so->so_tcpcb = tp;
+
+	return (tp);
+}
+
+/*
+ * Drop a TCP connection, reporting
+ * the specified error.  If connection is synchronized,
+ * then send a RST to peer.
+ */
+struct tcpcb *tcp_drop(struct tcpcb *tp, int errno) 
+{
+/* tcp_drop(tp, errno)
+	register struct tcpcb *tp;
+	int errno;
+{
+*/
+
+	DEBUG_CALL("tcp_drop");
+	DEBUG_ARG("tp = %lx", (long)tp);
+	DEBUG_ARG("errno = %d", errno);
+	
+	if (TCPS_HAVERCVDSYN(tp->t_state)) {
+		tp->t_state = TCPS_CLOSED;
+		(void) tcp_output(tp);
+		tcpstat.tcps_drops++;
+	} else
+		tcpstat.tcps_conndrops++;
+/*	if (errno == ETIMEDOUT && tp->t_softerror)
+ *		errno = tp->t_softerror;
+ */
+/*	so->so_error = errno; */
+	return (tcp_close(tp));
+}
+
+/*
+ * Close a TCP control block:
+ *	discard all space held by the tcp
+ *	discard internet protocol block
+ *	wake up any sleepers
+ */
+struct tcpcb *
+tcp_close(tp)
+	register struct tcpcb *tp;
+{
+	register struct tcpiphdr *t;
+	struct socket *so = tp->t_socket;
+	register struct mbuf *m;
+
+	DEBUG_CALL("tcp_close");
+	DEBUG_ARG("tp = %lx", (long )tp);
+	
+	/* free the reassembly queue, if any */
+	t = (struct tcpiphdr *) tp->seg_next;
+	while (t != (struct tcpiphdr *)tp) {
+		t = (struct tcpiphdr *)t->ti_next;
+		m = (struct mbuf *) REASS_MBUF((struct tcpiphdr *)t->ti_prev);
+		remque_32((struct tcpiphdr *) t->ti_prev);
+		m_freem(m);
+	}
+	/* It's static */
+/*	if (tp->t_template)
+ *		(void) m_free(dtom(tp->t_template));
+ */
+/*	free(tp, M_PCB);  */
+	free(tp);
+	so->so_tcpcb = 0;
+	soisfdisconnected(so);
+	/* clobber input socket cache if we're closing the cached connection */
+	if (so == tcp_last_so)
+		tcp_last_so = &tcb;
+	close(so->s);
+	sbfree(&so->so_rcv);
+	sbfree(&so->so_snd);
+	sofree(so);
+	tcpstat.tcps_closed++;
+	return ((struct tcpcb *)0);
+}
+
+void
+tcp_drain()
+{
+	/* XXX */
+}
+
+/*
+ * When a source quench is received, close congestion window
+ * to one segment.  We will gradually open it again as we proceed.
+ */
+
+#ifdef notdef
+
+void
+tcp_quench(i, errno)
+
+	int errno;
+{
+	struct tcpcb *tp = intotcpcb(inp);
+
+	if (tp)
+		tp->snd_cwnd = tp->t_maxseg;
+}
+
+#endif /* notdef */
+
+/*
+ * TCP protocol interface to socket abstraction.
+ */
+
+/*
+ * User issued close, and wish to trail through shutdown states:
+ * if never received SYN, just forget it.  If got a SYN from peer,
+ * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
+ * If already got a FIN from peer, then almost done; go to LAST_ACK
+ * state.  In all other cases, have already sent FIN to peer (e.g.
+ * after PRU_SHUTDOWN), and just have to play tedious game waiting
+ * for peer to send FIN or not respond to keep-alives, etc.
+ * We can let the user exit from the close as soon as the FIN is acked.
+ */
+void
+tcp_sockclosed(tp)
+	struct tcpcb *tp;
+{
+
+	DEBUG_CALL("tcp_sockclosed");
+	DEBUG_ARG("tp = %lx", (long)tp);
+	
+	switch (tp->t_state) {
+
+	case TCPS_CLOSED:
+	case TCPS_LISTEN:
+	case TCPS_SYN_SENT:
+		tp->t_state = TCPS_CLOSED;
+		tp = tcp_close(tp);
+		break;
+
+	case TCPS_SYN_RECEIVED:
+	case TCPS_ESTABLISHED:
+		tp->t_state = TCPS_FIN_WAIT_1;
+		break;
+
+	case TCPS_CLOSE_WAIT:
+		tp->t_state = TCPS_LAST_ACK;
+		break;
+	}
+/*	soisfdisconnecting(tp->t_socket); */
+	if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
+		soisfdisconnected(tp->t_socket);
+	if (tp)
+		tcp_output(tp);
+}
+
+/* 
+ * Connect to a host on the Internet
+ * Called by tcp_input
+ * Only do a connect, the tcp fields will be set in tcp_input
+ * return 0 if there's a result of the connect,
+ * else return -1 means we're still connecting
+ * The return value is almost always -1 since the socket is
+ * nonblocking.  Connect returns after the SYN is sent, and does 
+ * not wait for ACK+SYN.
+ */
+int tcp_fconnect(so)
+     struct socket *so;
+{
+  int ret=0;
+  
+  DEBUG_CALL("tcp_fconnect");
+  DEBUG_ARG("so = %lx", (long )so);
+
+  if( (ret=so->s=socket(AF_INET,SOCK_STREAM,0)) >= 0) {
+    int opt, s=so->s;
+    struct sockaddr_in addr;
+
+    fd_nonblock(s);
+    opt = 1;
+    setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(opt ));
+    opt = 1;
+    setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(opt ));
+    
+    addr.sin_family = AF_INET;
+    if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
+      /* It's an alias */
+      switch(ntohl(so->so_faddr.s_addr) & 0xff) {
+      case CTL_DNS:
+	addr.sin_addr = dns_addr;
+	break;
+      case CTL_ALIAS:
+      default:
+	addr.sin_addr = loopback_addr;
+	break;
+      }
+    } else
+      addr.sin_addr = so->so_faddr;
+    addr.sin_port = so->so_fport;
+    
+    DEBUG_MISC((dfd, " connect()ing, addr.sin_port=%d, "
+		"addr.sin_addr.s_addr=%.16s\n", 
+		ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));
+    /* We don't care what port we get */
+    ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));
+    
+    /*
+     * If it's not in progress, it failed, so we just return 0,
+     * without clearing SS_NOFDREF
+     */
+    soisfconnecting(so);
+  }
+
+  return(ret);
+}
+
+/*
+ * Accept the socket and connect to the local-host
+ * 
+ * We have a problem. The correct thing to do would be
+ * to first connect to the local-host, and only if the
+ * connection is accepted, then do an accept() here.
+ * But, a) we need to know who's trying to connect 
+ * to the socket to be able to SYN the local-host, and
+ * b) we are already connected to the foreign host by
+ * the time it gets to accept(), so... We simply accept
+ * here and SYN the local-host.
+ */ 
+void
+tcp_connect(inso)
+	struct socket *inso;
+{
+	struct socket *so;
+	struct sockaddr_in addr;
+	int addrlen = sizeof(struct sockaddr_in);
+	struct tcpcb *tp;
+	int s, opt;
+
+	DEBUG_CALL("tcp_connect");
+	DEBUG_ARG("inso = %lx", (long)inso);
+	
+	/*
+	 * If it's an SS_ACCEPTONCE socket, no need to socreate()
+	 * another socket, just use the accept() socket.
+	 */
+	if (inso->so_state & SS_FACCEPTONCE) {
+		/* FACCEPTONCE already have a tcpcb */
+		so = inso;
+	} else {
+		if ((so = socreate()) == NULL) {
+			/* If it failed, get rid of the pending connection */
+			close(accept(inso->s,(struct sockaddr *)&addr,&addrlen));
+			return;
+		}
+		if (tcp_attach(so) < 0) {
+			free(so); /* NOT sofree */
+			return;
+		}
+		so->so_laddr = inso->so_laddr;
+		so->so_lport = inso->so_lport;
+	}
+	
+	(void) tcp_mss(sototcpcb(so), 0);
+
+	if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {
+		tcp_close(sototcpcb(so)); /* This will sofree() as well */
+		return;
+	}
+	fd_nonblock(s);
+	opt = 1;
+	setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
+	opt = 1;
+	setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int));
+	
+	so->so_fport = addr.sin_port;
+	so->so_faddr = addr.sin_addr;
+	/* Translate connections from localhost to the real hostname */
+	if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)
+	   so->so_faddr = our_addr;
+	
+	/* Close the accept() socket, set right state */
+	if (inso->so_state & SS_FACCEPTONCE) {
+		close(so->s); /* If we only accept once, close the accept() socket */
+		so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */
+					   /* if it's not FACCEPTONCE, it's already NOFDREF */
+	}
+	so->s = s;
+	
+	so->so_iptos = tcp_tos(so);
+	tp = sototcpcb(so);
+
+	tcp_template(tp);
+	
+	/* Compute window scaling to request.  */
+/*	while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
+ *		(TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
+ *		tp->request_r_scale++;
+ */
+
+/*	soisconnecting(so); */ /* NOFDREF used instead */
+	tcpstat.tcps_connattempt++;
+	
+	tp->t_state = TCPS_SYN_SENT;
+	tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
+	tp->iss = tcp_iss; 
+	tcp_iss += TCP_ISSINCR/2;
+	tcp_sendseqinit(tp);
+	tcp_output(tp);
+}
+
+/*
+ * Attach a TCPCB to a socket.
+ */
+int
+tcp_attach(so)
+	struct socket *so;
+{
+	if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)
+	   return -1;
+	
+	insque(so, &tcb);
+
+	return 0;
+}
+
+/*
+ * Set the socket's type of service field
+ */
+struct tos_t tcptos[] = {
+	  {0, 20, IPTOS_THROUGHPUT, 0},	/* ftp data */
+	  {21, 21, IPTOS_LOWDELAY,  EMU_FTP},	/* ftp control */
+	  {0, 23, IPTOS_LOWDELAY, 0},	/* telnet */
+	  {0, 80, IPTOS_THROUGHPUT, 0},	/* WWW */
+	  {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN|EMU_NOCONNECT},	/* rlogin */
+	  {0, 514, IPTOS_LOWDELAY, EMU_RSH|EMU_NOCONNECT},	/* shell */
+	  {0, 544, IPTOS_LOWDELAY, EMU_KSH},		/* kshell */
+	  {0, 543, IPTOS_LOWDELAY, 0},	/* klogin */
+	  {0, 6667, IPTOS_THROUGHPUT, EMU_IRC},	/* IRC */
+	  {0, 6668, IPTOS_THROUGHPUT, EMU_IRC},	/* IRC undernet */
+	  {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO }, /* RealAudio control */
+	  {0, 113, IPTOS_LOWDELAY, EMU_IDENT }, /* identd protocol */
+	  {0, 0, 0, 0}
+};
+
+struct emu_t *tcpemu = 0;
+		
+/*
+ * Return TOS according to the above table
+ */
+u_int8_t
+tcp_tos(so)
+	struct socket *so;
+{
+	int i = 0;
+	struct emu_t *emup;
+	
+	while(tcptos[i].tos) {
+		if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
+		    (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
+			so->so_emu = tcptos[i].emu;
+			return tcptos[i].tos;
+		}
+		i++;
+	}
+	
+	/* Nope, lets see if there's a user-added one */
+	for (emup = tcpemu; emup; emup = emup->next) {
+		if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||
+		    (emup->lport && (ntohs(so->so_lport) == emup->lport))) {
+			so->so_emu = emup->emu;
+			return emup->tos;
+		}
+	}
+	
+	return 0;
+}
+
+int do_echo = -1;
+
+/*
+ * Emulate programs that try and connect to us
+ * This includes ftp (the data connection is
+ * initiated by the server) and IRC (DCC CHAT and
+ * DCC SEND) for now
+ * 
+ * NOTE: It's possible to crash SLiRP by sending it
+ * unstandard strings to emulate... if this is a problem,
+ * more checks are needed here
+ *
+ * XXX Assumes the whole command came in one packet
+ *					    
+ * XXX Some ftp clients will have their TOS set to
+ * LOWDELAY and so Nagel will kick in.  Because of this,
+ * we'll get the first letter, followed by the rest, so
+ * we simply scan for ORT instead of PORT...
+ * DCC doesn't have this problem because there's other stuff
+ * in the packet before the DCC command.
+ * 
+ * Return 1 if the mbuf m is still valid and should be 
+ * sbappend()ed
+ * 
+ * NOTE: if you return 0 you MUST m_free() the mbuf!
+ */
+int
+tcp_emu(so, m)
+	struct socket *so;
+	struct mbuf *m;
+{
+	u_int n1, n2, n3, n4, n5, n6;
+	char buff[256];
+	u_int32_t laddr;
+	u_int lport;
+	char *bptr;
+	
+	DEBUG_CALL("tcp_emu");
+	DEBUG_ARG("so = %lx", (long)so);
+	DEBUG_ARG("m = %lx", (long)m);
+	
+	switch(so->so_emu) {
+		int x, i;
+		
+	 case EMU_IDENT:
+		/*
+		 * Identification protocol as per rfc-1413
+		 */
+		
+		{
+			struct socket *tmpso;
+			struct sockaddr_in addr;
+			int addrlen = sizeof(struct sockaddr_in);
+			struct sbuf *so_rcv = &so->so_rcv;
+			
+			memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
+			so_rcv->sb_wptr += m->m_len;
+			so_rcv->sb_rptr += m->m_len;
+			m->m_data[m->m_len] = 0; /* NULL terminate */
+			if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
+				if (sscanf(so_rcv->sb_data, "%d%*[ ,]%d", &n1, &n2) == 2) {
+					HTONS(n1);
+					HTONS(n2);
+					/* n2 is the one on our host */
+					for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
+						if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr &&
+						    tmpso->so_lport == n2 &&
+						    tmpso->so_faddr.s_addr == so->so_faddr.s_addr &&
+						    tmpso->so_fport == n1) {
+							if (getsockname(tmpso->s,
+								(struct sockaddr *)&addr, &addrlen) == 0)
+							   n2 = ntohs(addr.sin_port);
+							break;
+						}
+					}
+				}
+				so_rcv->sb_cc = sprintf(so_rcv->sb_data, "%d,%d\r\n", n1, n2);
+				so_rcv->sb_rptr = so_rcv->sb_data;
+				so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
+			}
+			m_free(m);
+			return 0;
+		}
+		
+#if 0
+	 case EMU_RLOGIN:
+		/*
+		 * Rlogin emulation
+		 * First we accumulate all the initial option negotiation,
+		 * then fork_exec() rlogin according to the  options
+		 */
+		{
+			int i, i2, n;
+			char *ptr;
+			char args[100];
+			char term[100];
+			struct sbuf *so_snd = &so->so_snd;
+			struct sbuf *so_rcv = &so->so_rcv;
+			
+			/* First check if they have a priveladged port, or too much data has arrived */
+			if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
+			    (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
+				memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
+				so_snd->sb_wptr += 18;
+				so_snd->sb_cc += 18;
+				tcp_sockclosed(sototcpcb(so));
+				m_free(m);
+				return 0;
+			}
+			
+			/* Append the current data */
+			memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
+			so_rcv->sb_wptr += m->m_len;
+			so_rcv->sb_rptr += m->m_len;
+			m_free(m);
+			
+			/*
+			 * Check if we have all the initial options,
+			 * and build argument list to rlogin while we're here
+			 */
+			n = 0;
+			ptr = so_rcv->sb_data;
+			args[0] = 0;
+			term[0] = 0;
+			while (ptr < so_rcv->sb_wptr) {
+				if (*ptr++ == 0) {
+					n++;
+					if (n == 2) {
+						sprintf(args, "rlogin -l %s %s",
+							ptr, inet_ntoa(so->so_faddr));
+					} else if (n == 3) {
+						i2 = so_rcv->sb_wptr - ptr;
+						for (i = 0; i < i2; i++) {
+							if (ptr[i] == '/') {
+								ptr[i] = 0;
+#ifdef HAVE_SETENV
+								sprintf(term, "%s", ptr);
+#else
+								sprintf(term, "TERM=%s", ptr);
+#endif
+								ptr[i] = '/';
+								break;
+							}
+						}
+					}
+				}
+			}
+			
+			if (n != 4)
+			   return 0;
+			
+			/* We have it, set our term variable and fork_exec() */
+#ifdef HAVE_SETENV
+			setenv("TERM", term, 1);
+#else
+			putenv(term);
+#endif
+			fork_exec(so, args, 2);
+			term[0] = 0;
+			so->so_emu = 0;
+			
+			/* And finally, send the client a 0 character */
+			so_snd->sb_wptr[0] = 0;
+			so_snd->sb_wptr++;
+			so_snd->sb_cc++;
+			
+			return 0;
+		}
+		
+	 case EMU_RSH:
+		/*
+		 * rsh emulation
+		 * First we accumulate all the initial option negotiation,
+		 * then rsh_exec() rsh according to the  options
+		 */
+		{
+			int  n;
+			char *ptr;
+			char *user;
+			char *args;
+			struct sbuf *so_snd = &so->so_snd;
+			struct sbuf *so_rcv = &so->so_rcv;
+			
+			/* First check if they have a priveladged port, or too much data has arrived */
+			if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
+			    (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
+				memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
+				so_snd->sb_wptr += 18;
+				so_snd->sb_cc += 18;
+				tcp_sockclosed(sototcpcb(so));
+				m_free(m);
+				return 0;
+			}
+			
+			/* Append the current data */
+			memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
+			so_rcv->sb_wptr += m->m_len;
+			so_rcv->sb_rptr += m->m_len;
+			m_free(m);
+			
+			/*
+			 * Check if we have all the initial options,
+			 * and build argument list to rlogin while we're here
+			 */
+			n = 0;
+			ptr = so_rcv->sb_data;
+			user="";
+			args="";
+			if (so->extra==NULL) {
+				struct socket *ns;
+				struct tcpcb* tp;
+				int port=atoi(ptr);
+				if (port <= 0) return 0;
+                if (port > 1023 || port < 512) {
+                  memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
+                  so_snd->sb_wptr += 18;
+                  so_snd->sb_cc += 18;
+                  tcp_sockclosed(sototcpcb(so));
+                  return 0;
+                }
+				if ((ns=socreate()) == NULL)
+                  return 0;
+				if (tcp_attach(ns)<0) {
+                  free(ns);
+                  return 0;
+				}
+
+				ns->so_laddr=so->so_laddr;
+				ns->so_lport=htons(port);
+
+				(void) tcp_mss(sototcpcb(ns), 0);
+
+				ns->so_faddr=so->so_faddr;
+				ns->so_fport=htons(IPPORT_RESERVED-1); /* Use a fake port. */
+
+				if (ns->so_faddr.s_addr == 0 || 
+					ns->so_faddr.s_addr == loopback_addr.s_addr)
+                  ns->so_faddr = our_addr;
+
+				ns->so_iptos = tcp_tos(ns);
+				tp = sototcpcb(ns);
+                
+				tcp_template(tp);
+                
+				/* Compute window scaling to request.  */
+				/*	while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
+				 *		(TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
+				 *		tp->request_r_scale++;
+				 */
+
+                /*soisfconnecting(ns);*/
+
+				tcpstat.tcps_connattempt++;
+					
+				tp->t_state = TCPS_SYN_SENT;
+				tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
+				tp->iss = tcp_iss; 
+				tcp_iss += TCP_ISSINCR/2;
+				tcp_sendseqinit(tp);
+				tcp_output(tp);
+				so->extra=ns;
+			}
+			while (ptr < so_rcv->sb_wptr) {
+              if (*ptr++ == 0) {
+                n++;
+                if (n == 2) {
+                  user=ptr;
+                } else if (n == 3) {
+                  args=ptr;
+                }
+              }
+			}
+			
+			if (n != 4)
+              return 0;
+			
+			rsh_exec(so,so->extra, user, inet_ntoa(so->so_faddr), args);
+			so->so_emu = 0;
+			so->extra=NULL;
+			
+			/* And finally, send the client a 0 character */
+			so_snd->sb_wptr[0] = 0;
+			so_snd->sb_wptr++;
+			so_snd->sb_cc++;
+			
+			return 0;
+		}
+
+	 case EMU_CTL:
+		{
+			int num;
+			struct sbuf *so_snd = &so->so_snd;
+			struct sbuf *so_rcv = &so->so_rcv;
+			
+			/*
+			 * If there is binary data here, we save it in so->so_m
+			 */
+			if (!so->so_m) {
+			  int rxlen;
+			  char *rxdata;
+			  rxdata=mtod(m, char *);
+			  for (rxlen=m->m_len; rxlen; rxlen--) {
+			    if (*rxdata++ & 0x80) {
+			      so->so_m = m;
+			      return 0;
+			    }
+			  }
+			} /* if(so->so_m==NULL) */
+			
+			/*
+			 * Append the line
+			 */
+			sbappendsb(so_rcv, m);
+			
+			/* To avoid going over the edge of the buffer, we reset it */
+			if (so_snd->sb_cc == 0)
+			   so_snd->sb_wptr = so_snd->sb_rptr = so_snd->sb_data;
+			
+			/*
+			 * A bit of a hack:
+			 * If the first packet we get here is 1 byte long, then it
+			 * was done in telnet character mode, therefore we must echo
+			 * the characters as they come.  Otherwise, we echo nothing,
+			 * because in linemode, the line is already echoed
+			 * XXX two or more control connections won't work
+			 */
+			if (do_echo == -1) {
+				if (m->m_len == 1) do_echo = 1;
+				else do_echo = 0;
+			}
+			if (do_echo) {
+			  sbappendsb(so_snd, m);
+			  m_free(m);
+			  tcp_output(sototcpcb(so)); /* XXX */
+			} else
+			  m_free(m);
+			
+			num = 0;
+			while (num < so->so_rcv.sb_cc) {
+				if (*(so->so_rcv.sb_rptr + num) == '\n' ||
+				    *(so->so_rcv.sb_rptr + num) == '\r') {
+					int n;
+					
+					*(so_rcv->sb_rptr + num) = 0;
+					if (ctl_password && !ctl_password_ok) {
+						/* Need a password */
+						if (sscanf(so_rcv->sb_rptr, "pass %256s", buff) == 1) {
+							if (strcmp(buff, ctl_password) == 0) {
+								ctl_password_ok = 1;
+								n = sprintf(so_snd->sb_wptr,
+									    "Password OK.\r\n");
+								goto do_prompt;
+							}
+						}
+						n = sprintf(so_snd->sb_wptr,
+					 "Error: Password required, log on with \"pass PASSWORD\"\r\n");
+						goto do_prompt;
+					}
+					cfg_quitting = 0;
+					n = do_config(so_rcv->sb_rptr, so, PRN_SPRINTF);
+					if (!cfg_quitting) {
+						/* Register the printed data */
+do_prompt:
+						so_snd->sb_cc += n;
+						so_snd->sb_wptr += n;
+						/* Add prompt */
+						n = sprintf(so_snd->sb_wptr, "Slirp> ");
+						so_snd->sb_cc += n;
+						so_snd->sb_wptr += n;
+					}
+					/* Drop so_rcv data */
+					so_rcv->sb_cc = 0;
+					so_rcv->sb_wptr = so_rcv->sb_rptr = so_rcv->sb_data;
+					tcp_output(sototcpcb(so)); /* Send the reply */
+				}
+				num++;
+			}
+			return 0;
+		}
+#endif		
+        case EMU_FTP: /* ftp */
+		*(m->m_data+m->m_len) = 0; /* NULL terminate for strstr */
+		if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
+			/*
+			 * Need to emulate the PORT command
+			 */			
+			x = sscanf(bptr, "ORT %d,%d,%d,%d,%d,%d\r\n%256[^\177]", 
+				   &n1, &n2, &n3, &n4, &n5, &n6, buff);
+			if (x < 6)
+			   return 1;
+			
+			laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
+			lport = htons((n5 << 8) | (n6));
+			
+			if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
+			   return 1;
+			
+			n6 = ntohs(so->so_fport);
+			
+			n5 = (n6 >> 8) & 0xff;
+			n6 &= 0xff;
+			
+			laddr = ntohl(so->so_faddr.s_addr);
+			
+			n1 = ((laddr >> 24) & 0xff);
+			n2 = ((laddr >> 16) & 0xff);
+			n3 = ((laddr >> 8)  & 0xff);
+			n4 =  (laddr & 0xff);
+			
+			m->m_len = bptr - m->m_data; /* Adjust length */
+			m->m_len += sprintf(bptr,"ORT %d,%d,%d,%d,%d,%d\r\n%s", 
+					    n1, n2, n3, n4, n5, n6, x==7?buff:"");
+			return 1;
+		} else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
+			/*
+			 * Need to emulate the PASV response
+			 */
+			x = sscanf(bptr, "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%256[^\177]",
+				   &n1, &n2, &n3, &n4, &n5, &n6, buff);
+			if (x < 6)
+			   return 1;
+			
+			laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
+			lport = htons((n5 << 8) | (n6));
+			
+			if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
+			   return 1;
+			
+			n6 = ntohs(so->so_fport);
+			
+			n5 = (n6 >> 8) & 0xff;
+			n6 &= 0xff;
+			
+			laddr = ntohl(so->so_faddr.s_addr);
+			
+			n1 = ((laddr >> 24) & 0xff);
+			n2 = ((laddr >> 16) & 0xff);
+			n3 = ((laddr >> 8)  & 0xff);
+			n4 =  (laddr & 0xff);
+			
+			m->m_len = bptr - m->m_data; /* Adjust length */
+			m->m_len += sprintf(bptr,"27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s",
+					    n1, n2, n3, n4, n5, n6, x==7?buff:"");
+			
+			return 1;
+		}
+		
+		return 1;
+				   
+	 case EMU_KSH:
+		/*
+		 * The kshell (Kerberos rsh) and shell services both pass
+		 * a local port port number to carry signals to the server
+		 * and stderr to the client.  It is passed at the beginning
+		 * of the connection as a NUL-terminated decimal ASCII string.
+		 */
+		so->so_emu = 0;
+		for (lport = 0, i = 0; i < m->m_len-1; ++i) {
+			if (m->m_data[i] < '0' || m->m_data[i] > '9')
+				return 1;       /* invalid number */
+			lport *= 10;
+			lport += m->m_data[i] - '0';
+		}
+		if (m->m_data[m->m_len-1] == '\0' && lport != 0 &&
+		    (so = solisten(0, so->so_laddr.s_addr, htons(lport), SS_FACCEPTONCE)) != NULL)
+			m->m_len = sprintf(m->m_data, "%d", ntohs(so->so_fport))+1;
+		return 1;
+		
+	 case EMU_IRC:
+		/*
+		 * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
+		 */
+		*(m->m_data+m->m_len) = 0; /* NULL terminate the string for strstr */
+		if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
+			 return 1;
+		
+		/* The %256s is for the broken mIRC */
+		if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
+			if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
+				return 1;
+			
+			m->m_len = bptr - m->m_data; /* Adjust length */
+			m->m_len += sprintf(bptr, "DCC CHAT chat %lu %u%c\n",
+			     (unsigned long)ntohl(so->so_faddr.s_addr),
+			     ntohs(so->so_fport), 1);
+		} else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
+			if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
+				return 1;
+			
+			m->m_len = bptr - m->m_data; /* Adjust length */
+			m->m_len += sprintf(bptr, "DCC SEND %s %lu %u %u%c\n", 
+			      buff, (unsigned long)ntohl(so->so_faddr.s_addr),
+			      ntohs(so->so_fport), n1, 1);
+		} else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
+			if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
+				return 1;
+			
+			m->m_len = bptr - m->m_data; /* Adjust length */
+			m->m_len += sprintf(bptr, "DCC MOVE %s %lu %u %u%c\n",
+			      buff, (unsigned long)ntohl(so->so_faddr.s_addr),
+			      ntohs(so->so_fport), n1, 1);
+		}
+		return 1;
+
+	 case EMU_REALAUDIO:
+                /* 
+		 * RealAudio emulation - JP. We must try to parse the incoming
+		 * data and try to find the two characters that contain the
+		 * port number. Then we redirect an udp port and replace the
+		 * number with the real port we got.
+		 *
+		 * The 1.0 beta versions of the player are not supported
+		 * any more.
+		 * 
+		 * A typical packet for player version 1.0 (release version):
+		 *        
+		 * 0000:50 4E 41 00 05 
+		 * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 .....×..gælÜc..P
+		 * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
+		 * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
+		 * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
+		 *         
+		 * Now the port number 0x1BD7 is found at offset 0x04 of the
+		 * Now the port number 0x1BD7 is found at offset 0x04 of the
+		 * second packet. This time we received five bytes first and
+		 * then the rest. You never know how many bytes you get.
+		 *
+		 * A typical packet for player version 2.0 (beta):
+		 *        
+		 * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA...........Á.
+		 * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .guxõc..Win2.0.0
+		 * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
+		 * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
+		 * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
+		 *        
+		 * Port number 0x1BC1 is found at offset 0x0d.
+		 *      
+		 * This is just a horrible switch statement. Variable ra tells
+		 * us where we're going.
+		 */
+		
+		bptr = m->m_data;
+		while (bptr < m->m_data + m->m_len) {
+			u_short p;
+			static int ra = 0;
+			char ra_tbl[4]; 
+			
+			ra_tbl[0] = 0x50;
+			ra_tbl[1] = 0x4e;
+			ra_tbl[2] = 0x41;
+			ra_tbl[3] = 0;
+			
+			switch (ra) {
+			 case 0:
+			 case 2:
+			 case 3:
+				if (*bptr++ != ra_tbl[ra]) {
+					ra = 0;
+					continue;
+				}
+				break;
+				
+			 case 1:
+				/*
+				 * We may get 0x50 several times, ignore them
+				 */
+				if (*bptr == 0x50) {
+					ra = 1;
+					bptr++;
+					continue;
+				} else if (*bptr++ != ra_tbl[ra]) {
+					ra = 0;
+					continue;
+				}
+				break;
+				
+			 case 4: 
+				/* 
+				 * skip version number
+				 */
+				bptr++;
+				break;
+				
+			 case 5: 
+				/*
+				 * The difference between versions 1.0 and
+				 * 2.0 is here. For future versions of
+				 * the player this may need to be modified.
+				 */
+				if (*(bptr + 1) == 0x02)
+				   bptr += 8;
+				else
+				   bptr += 4;
+				break;                          
+				
+			 case 6:
+				/* This is the field containing the port
+				 * number that RA-player is listening to.
+				 */
+				lport = (((u_char*)bptr)[0] << 8) 
+				+ ((u_char *)bptr)[1];
+				if (lport < 6970)      
+				   lport += 256;   /* don't know why */
+				if (lport < 6970 || lport > 7170)
+				   return 1;       /* failed */
+				
+				/* try to get udp port between 6970 - 7170 */
+				for (p = 6970; p < 7071; p++) {
+					if (udp_listen( htons(p),
+						       so->so_laddr.s_addr,
+						       htons(lport),
+						       SS_FACCEPTONCE)) {
+						break;
+					}
+				}
+				if (p == 7071)
+				   p = 0;
+				*(u_char *)bptr++ = (p >> 8) & 0xff;
+				*(u_char *)bptr++ = p & 0xff;
+				ra = 0; 
+				return 1;   /* port redirected, we're done */
+				break;  
+				
+			 default:
+				ra = 0;                         
+			}
+			ra++;
+		}
+		return 1;                                
+		
+	 default:
+		/* Ooops, not emulated, won't call tcp_emu again */
+		so->so_emu = 0;
+		return 1;
+	}
+}
+
+/*
+ * Do misc. config of SLiRP while its running.
+ * Return 0 if this connections is to be closed, 1 otherwise,
+ * return 2 if this is a command-line connection
+ */
+int
+tcp_ctl(so)
+	struct socket *so;
+{
+#if 0
+	struct sbuf *sb = &so->so_snd;
+	int command;
+ 	struct ex_list *ex_ptr;
+	int do_pty;
+	struct socket *tmpso;
+	
+	DEBUG_CALL("tcp_ctl");
+	DEBUG_ARG("so = %lx", (long )so);
+	
+	/*
+	 * Check if they're authorised
+	 */
+	if (ctl_addr.s_addr && (ctl_addr.s_addr == -1 || (so->so_laddr.s_addr != ctl_addr.s_addr))) {
+		sb->sb_cc = sprintf(sb->sb_wptr,"Error: Permission denied.\r\n");
+		sb->sb_wptr += sb->sb_cc;
+		return 0;
+	}
+	
+	command = (ntohl(so->so_faddr.s_addr) & 0xff);
+	
+	switch(command) {
+	default: /* Check for exec's */
+		
+		/*
+		 * Check if it's pty_exec
+		 */
+		for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
+			if (ex_ptr->ex_fport == so->so_fport &&
+			    command == ex_ptr->ex_addr) {
+				do_pty = ex_ptr->ex_pty;
+				goto do_exec;
+			}
+		}
+		
+		/*
+		 * Nothing bound..
+		 */
+		/* tcp_fconnect(so); */
+		
+		/* FALLTHROUGH */
+	case CTL_ALIAS:
+	  sb->sb_cc = sprintf(sb->sb_wptr,
+			      "Error: No application configured.\r\n");
+	  sb->sb_wptr += sb->sb_cc;
+	  return(0);
+
+	do_exec:
+		DEBUG_MISC((dfd, " executing %s \n",ex_ptr->ex_exec));
+		return(fork_exec(so, ex_ptr->ex_exec, do_pty));
+		
+	case CTL_CMD:
+	   for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
+	     if (tmpso->so_emu == EMU_CTL && 
+		 !(tmpso->so_tcpcb? 
+		   (tmpso->so_tcpcb->t_state & (TCPS_TIME_WAIT|TCPS_LAST_ACK))
+		   :0)) {
+	       /* Ooops, control connection already active */
+	       sb->sb_cc = sprintf(sb->sb_wptr,"Sorry, already connected.\r\n");
+	       sb->sb_wptr += sb->sb_cc;
+	       return 0;
+	     }
+	   }
+	   so->so_emu = EMU_CTL;
+	   ctl_password_ok = 0;
+	   sb->sb_cc = sprintf(sb->sb_wptr, "Slirp command-line ready (type \"help\" for help).\r\nSlirp> ");
+	   sb->sb_wptr += sb->sb_cc;
+	   do_echo=-1;
+	   return(2);
+	}
+#else
+        return 0;
+#endif
+}