tcp_subr.c

qemu虚拟机代码

/*
 * 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 err) 
{
/* 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;
	closesocket(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 */
			closesocket(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 = alias_addr;
	
	/* Close the accept() socket, set right state */
	if (inso->so_state & SS_FACCEPTONCE) {
		closesocket(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 */