typed mbufs

[unix-history] / usr / src / sys / netinet / tcp_output.c

diff --git a/usr/src/sys/netinet/tcp_output.c b/usr/src/sys/netinet/tcp_output.c
index bae98fa..6dc94b5 100644 (file)
--- a/usr/src/sys/netinet/tcp_output.c
+++ b/usr/src/sys/netinet/tcp_output.c
@@ -1,4 +1,4 @@
-/*     tcp_output.c    4.21    81/12/02        */
+/*     tcp_output.c    4.49    82/12/14        */

 
 #include "../h/param.h"
 #include "../h/systm.h"
 
 #include "../h/param.h"
 #include "../h/systm.h"


@@ -6,26 +6,31 @@
 #include "../h/protosw.h"
 #include "../h/socket.h"
 #include "../h/socketvar.h"
 #include "../h/protosw.h"
 #include "../h/socket.h"
 #include "../h/socketvar.h"

-#include "../net/in.h"
-#include "../net/in_pcb.h"
-#include "../net/in_systm.h"
-#include "../net/ip.h"
-#include "../net/ip_var.h"
-#include "../net/tcp.h"
+#include "../netinet/in.h"
+#include "../net/route.h"
+#include "../netinet/in_pcb.h"
+#include "../netinet/in_systm.h"
+#include "../netinet/ip.h"
+#include "../netinet/ip_var.h"
+#include "../netinet/tcp.h"

 #define        TCPOUTFLAGS
 #define        TCPOUTFLAGS

-#include "../net/tcp_fsm.h"
-#include "../net/tcp_seq.h"
-#include "../net/tcp_timer.h"
-#include "../net/tcp_var.h"
-#include "../net/tcpip.h"
-#include "../errno.h"
+#include "../netinet/tcp_fsm.h"
+#include "../netinet/tcp_seq.h"
+#include "../netinet/tcp_timer.h"
+#include "../netinet/tcp_var.h"
+#include "../netinet/tcpip.h"
+#include "../netinet/tcp_debug.h"
+#include <errno.h>
+
+char *tcpstates[]; /* XXX */
+
+/*
+ * Initial options.
+ */
+u_char tcp_initopt[4] = { TCPOPT_MAXSEG, 4, 0x0, 0x0, };

 
 /*
 
 /*

- * Tcp output routine: figure out what should be sent
- * and, if nothing, send a null segment anyways if force is nonzero
- * (e.g. to be sure to send an ACK).
- *
- * This routine can be called only after SYNs have been exchanged.
+ * Tcp output routine: figure out what should be sent and send it.

  */
 tcp_output(tp)
        register struct tcpcb *tp;
  */
 tcp_output(tp)
        register struct tcpcb *tp;


@@ -33,38 +38,60 @@ tcp_output(tp)
        register struct socket *so = tp->t_inpcb->inp_socket;
        register int len;
        struct mbuf *m0;
        register struct socket *so = tp->t_inpcb->inp_socket;
        register int len;
        struct mbuf *m0;

-       int off, flags;
+       int off, flags, win, error;

        register struct mbuf *m;
        register struct tcpiphdr *ti;
        register struct mbuf *m;
        register struct tcpiphdr *ti;

-       int win;
+       u_char *opt;
+       unsigned optlen = 0;
+       int sendalot;

 
 

-COUNT(TCP_OUTPUT);

 
        /*
 
        /*

-        * Determine length of data that can be transmitted,
+        * Determine length of data that should be transmitted,

         * and flags that will be used.
         * If there is some data or critical controls (SYN, RST)
         * to send, then transmit; otherwise, investigate further.
         */
         * and flags that will be used.
         * If there is some data or critical controls (SYN, RST)
         * to send, then transmit; otherwise, investigate further.
         */

+again:
+       sendalot = 0;

        off = tp->snd_nxt - tp->snd_una;
        len = MIN(so->so_snd.sb_cc, tp->snd_wnd+tp->t_force) - off;
        off = tp->snd_nxt - tp->snd_una;
        len = MIN(so->so_snd.sb_cc, tp->snd_wnd+tp->t_force) - off;

-       if (len > tp->t_maxseg)
+       if (len < 0)
+               return (0);     /* ??? */       /* past FIN */
+       if (len > tp->t_maxseg) {

                len = tp->t_maxseg;
                len = tp->t_maxseg;

+               sendalot = 1;
+       }
+

        flags = tcp_outflags[tp->t_state];
        flags = tcp_outflags[tp->t_state];

-       if (len < so->so_snd.sb_cc)
+       if (tp->snd_nxt + len < tp->snd_una + so->so_snd.sb_cc)

                flags &= ~TH_FIN;
                flags &= ~TH_FIN;

-       if (len || (flags & (TH_SYN|TH_RST)))
+       if (flags & (TH_SYN|TH_RST|TH_FIN))
+               goto send;
+       if (SEQ_GT(tp->snd_up, tp->snd_una))

                goto send;
 
        /*
                goto send;
 
        /*

-        * See if we owe peer an ACK or have a unacked FIN to send.
+        * Sender silly window avoidance.  If can send all data,
+        * a maximum segment, at least 1/4 of window do it,
+        * or are forced, do it; otherwise don't bother.

         */
         */

-       if (tp->t_flags & TF_ACKNOW)
-               goto send;
-       if ((so->so_state & SS_CANTSENDMORE) &&
-           TCPS_OURFINNOTACKED(tp->t_state))
+       if (len) {
+               if (len == tp->t_maxseg || off+len >= so->so_snd.sb_cc)
+                       goto send;
+               if (len * 4 >= tp->snd_wnd)             /* a lot */
+                       goto send;
+               if (tp->t_force)
+                       goto send;
+       }
+
+       /*
+        * Send if we owe peer an ACK.
+        */
+       if (tp->t_flags&TF_ACKNOW)

                goto send;
 
                goto send;
 

+

        /*
         * Calculate available window in i, and also amount
         * of window known to peer (as advertised window less
        /*
         * Calculate available window in i, and also amount
         * of window known to peer (as advertised window less


@@ -76,6 +103,33 @@ COUNT(TCP_OUTPUT);
            ((100*(win-(tp->rcv_adv-tp->rcv_nxt))/so->so_rcv.sb_hiwat) >= 35))
                goto send;
 
            ((100*(win-(tp->rcv_adv-tp->rcv_nxt))/so->so_rcv.sb_hiwat) >= 35))
                goto send;
 

+       /*
+        * TCP window updates are not reliable, rather a polling protocol
+        * using ``persist'' packets is used to insure receipt of window
+        * updates.  The three ``states'' for the output side are:
+        *      idle                    not doing retransmits or persists
+        *      persisting              to move a zero window
+        *      (re)transmitting        and thereby not persisting
+        *
+        * tp->t_timer[TCPT_PERSIST]
+        *      is set when we are in persist state.
+        * tp->t_force
+        *      is set when we are called to send a persist packet.
+        * tp->t_timer[TCPT_REXMT]
+        *      is set when we are retransmitting
+        * The output side is idle when both timers are zero.
+        *
+        * If send window is closed, there is data to transmit, and no
+        * retransmit or persist is pending, then go to persist state,
+        * arranging to force out a byte to get more current window information
+        * if nothing happens soon.
+        */
+       if (tp->snd_wnd == 0 && so->so_snd.sb_cc &&
+           tp->t_timer[TCPT_REXMT] == 0 && tp->t_timer[TCPT_PERSIST] == 0) {
+               tp->t_rxtshift = 0;
+               tcp_setpersist(tp);
+       }
+

        /*
         * No reason to send a segment, just return.
         */
        /*
         * No reason to send a segment, just return.
         */


@@ -87,10 +141,10 @@ send:
         * be transmitted, and initialize the header from
         * the template for sends on this connection.
         */
         * be transmitted, and initialize the header from
         * the template for sends on this connection.
         */

-       MGET(m, 0);
+       MGET(m, M_DONTWAIT, MT_DATA);

        if (m == 0)
        if (m == 0)

-               return (0);
-       m->m_off = MMAXOFF - sizeof(struct tcpiphdr);
+               return (ENOBUFS);
+       m->m_off = MMAXOFF - sizeof (struct tcpiphdr);

        m->m_len = sizeof (struct tcpiphdr);
        if (len) {
                m->m_next = m_copy(so->so_snd.sb_mb, off, len);
        m->m_len = sizeof (struct tcpiphdr);
        if (len) {
                m->m_next = m_copy(so->so_snd.sb_mb, off, len);


@@ -106,29 +160,57 @@ send:
         * Fill in fields, remembering maximum advertised
         * window for use in delaying messages about window sizes.
         */
         * Fill in fields, remembering maximum advertised
         * window for use in delaying messages about window sizes.
         */

-       ti->ti_seq = htonl(tp->snd_nxt);
-       ti->ti_ack = htonl(tp->rcv_nxt);
-       if (tp->t_tcpopt) {
+       ti->ti_seq = tp->snd_nxt;
+       ti->ti_ack = tp->rcv_nxt;
+       ti->ti_seq = htonl(ti->ti_seq);
+       ti->ti_ack = htonl(ti->ti_ack);
+       /*
+        * Before ESTABLISHED, force sending of initial options
+        * unless TCP set to not do any options.
+        */
+       if (tp->t_state < TCPS_ESTABLISHED) {
+               if (tp->t_flags&TF_NOOPT)
+                       goto noopt;
+               opt = tcp_initopt;
+               optlen = sizeof (tcp_initopt);
+               *(u_short *)(opt + 2) = MIN(so->so_rcv.sb_hiwat / 2, 1024);
+               *(u_short *)(opt + 2) = htons(*(u_short *)(opt + 2));
+       } else {
+               if (tp->t_tcpopt == 0)
+                       goto noopt;
+               opt = mtod(tp->t_tcpopt, u_char *);
+               optlen = tp->t_tcpopt->m_len;
+       }
+       if (opt) {

                m0 = m->m_next;
                m0 = m->m_next;

-               m->m_next = m_get(0);
+               m->m_next = m_get(M_DONTWAIT, MT_DATA);

                if (m->m_next == 0) {
                        (void) m_free(m);
                if (m->m_next == 0) {
                        (void) m_free(m);

-                       m_freem(m);
-                       return (0);
+                       m_freem(m0);
+                       return (ENOBUFS);

                }
                m->m_next->m_next = m0;
                }
                m->m_next->m_next = m0;

-               m->m_off = MMINOFF;
-               m->m_len = tp->t_tcpopt->m_len;
-               bcopy(mtod(tp->t_tcpopt, caddr_t), mtod(m, caddr_t),
-                   (unsigned)tp->t_tcpopt->m_len);
-               ti->ti_off = (sizeof (struct tcphdr)+tp->t_tcpopt->m_len) >> 2;
+               m0 = m->m_next;
+               m0->m_len = optlen;
+               bcopy((caddr_t)opt, mtod(m0, caddr_t), optlen);
+               opt = (u_char *)(mtod(m0, caddr_t) + optlen);
+               while (m0->m_len & 0x3) {
+                       *opt++ = TCPOPT_EOL;
+                       m0->m_len++;
+               }
+               optlen = m0->m_len;
+               ti->ti_off = (sizeof (struct tcphdr) + optlen) >> 2;

        }
        }

+noopt:

        ti->ti_flags = flags;
        win = sbspace(&so->so_rcv);
        ti->ti_flags = flags;
        win = sbspace(&so->so_rcv);

+       if (win < so->so_rcv.sb_hiwat / 4)      /* avoid silly window */
+               win = 0;

        if (win > 0)
                ti->ti_win = htons((u_short)win);
        if (SEQ_GT(tp->snd_up, tp->snd_nxt)) {
        if (win > 0)
                ti->ti_win = htons((u_short)win);
        if (SEQ_GT(tp->snd_up, tp->snd_nxt)) {

-               ti->ti_urp = htons((u_short)(tp->snd_up - tp->snd_nxt));
+               ti->ti_urp = tp->snd_up - tp->snd_nxt;
+               ti->ti_urp = htons(ti->ti_urp);

                ti->ti_flags |= TH_URG;
        } else
                /*
                ti->ti_flags |= TH_URG;
        } else
                /*


@@ -138,80 +220,110 @@ send:
                 * number wraparound.
                 */
                tp->snd_up = tp->snd_una;               /* drag it along */
                 * number wraparound.
                 */
                tp->snd_up = tp->snd_una;               /* drag it along */

-       /* PUSH */
+       /*
+        * If anything to send and we can send it all, set PUSH.
+        * (This will keep happy those implementations which only
+        * give data to the user when a buffer fills or a PUSH comes in.
+        */
+       if (len && off+len == so->so_snd.sb_cc)
+               ti->ti_flags |= TH_PUSH;

 
        /*
         * Put TCP length in extended header, and then
         * checksum extended header and data.
         */
 
        /*
         * Put TCP length in extended header, and then
         * checksum extended header and data.
         */

-       if (len)
-               ti->ti_len = htons((u_short)(len + sizeof (struct tcphdr)));
-       ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + len);
+       if (len + optlen) {
+               ti->ti_len = sizeof (struct tcphdr) + optlen + len;
+               ti->ti_len = htons((u_short)ti->ti_len);
+       }
+       ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + (int)optlen + len);

 
        /*
 
        /*

-        * Advance snd_nxt over sequence space of this segment
+        * In transmit state, time the transmission and arrange for
+        * the retransmit.  In persist state, reset persist time for
+        * next persist.

         */
         */

-       if (flags & (TH_SYN|TH_FIN))
-               len++;
-       tp->snd_nxt += len;
+       if (tp->t_force == 0) {
+               /*
+                * Advance snd_nxt over sequence space of this segment.
+                */
+               if (flags & (TH_SYN|TH_FIN))
+                       tp->snd_nxt++;
+               tp->snd_nxt += len;
+               if (SEQ_GT(tp->snd_nxt, tp->snd_max))
+                       tp->snd_max = tp->snd_nxt;

 
 

-       /*
-        * If this transmission closes the window,
-        * start persistance timer at 2 round trip
-        * times but at least TCPTV_PERSMIN ticks.
-        */
-       if (tp->snd_una + tp->snd_wnd >= tp->snd_nxt &&
-           tp->t_timer[TCPT_PERSIST] == 0) {
-               tp->t_timer[TCPT_PERSIST] = 2 * tp->t_srtt;
-               if (tp->t_timer[TCPT_PERSIST] < TCPTV_PERSMIN)
-                       tp->t_timer[TCPT_PERSIST] = TCPTV_PERSMIN;
-               if (tp->t_timer[TCPT_PERSIST] > TCPTV_MAX)
-                       tp->t_timer[TCPT_PERSIST] = TCPTV_MAX;
-       }
+               /*
+                * Time this transmission if not a retransmission and
+                * not currently timing anything.
+                */
+               if (SEQ_GT(tp->snd_nxt, tp->snd_max) && tp->t_rtt == 0) {
+                       tp->t_rtt = 1;
+                       tp->t_rtseq = tp->snd_nxt - len;
+               }

 
 

-       /*
-        * Time this transmission if not a retransmission and
-        * not currently timing anything.
-        */
-       if (SEQ_GT(tp->snd_nxt, tp->snd_max) && tp->t_rtt == 0) {
-               tp->t_rtt = 1;
-               tp->t_rtseq = tp->snd_nxt - len;
+               /*
+                * Set retransmit timer if not currently set.
+                * Initial value for retransmit timer to tcp_beta*tp->t_srtt.
+                * Initialize shift counter which is used for exponential
+                * backoff of retransmit time.
+                */
+               if (tp->t_timer[TCPT_REXMT] == 0 &&
+                   tp->snd_nxt != tp->snd_una) {
+                       TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
+                           tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX);
+                       tp->t_rtt = 0;
+                       tp->t_rxtshift = 0;
+               }
+               tp->t_timer[TCPT_PERSIST] = 0;
+       } else {
+               if (SEQ_GT(tp->snd_una+1, tp->snd_max))
+                       tp->snd_max = tp->snd_una+1;

        }
 
        /*
        }
 
        /*

-        * Set retransmit timer if not currently set.
-        * Initial value for retransmit timer to tcp_beta*tp->t_srtt,
-        * with a minimum of TCPTV_MIN and a max of TCPTV_MAX.
-        * Initialize shift counter which is used for exponential
-        * backoff of retransmit time.
+        * Trace.

         */
         */

-       if (tp->t_timer[TCPT_REXMT] == 0) {
-               tp->t_timer[TCPT_REXMT] = tcp_beta * tp->t_srtt;
-               if (tp->t_timer[TCPT_REXMT] < TCPTV_MIN)
-                       tp->t_timer[TCPT_REXMT] = TCPTV_MIN;
-               if (tp->t_timer[TCPT_REXMT] > TCPTV_MAX)
-                       tp->t_timer[TCPT_REXMT] = TCPTV_MAX;
-               tp->t_rxtshift = 0;
-       }
+       if (so->so_options & SO_DEBUG)
+               tcp_trace(TA_OUTPUT, tp->t_state, tp, ti, 0);

 
        /*
         * Fill in IP length and desired time to live and
         * send to IP level.
         */
 
        /*
         * Fill in IP length and desired time to live and
         * send to IP level.
         */

-       ((struct ip *)ti)->ip_len = len + sizeof (struct tcpiphdr);
+       ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + optlen + len;

        ((struct ip *)ti)->ip_ttl = TCP_TTL;
        ((struct ip *)ti)->ip_ttl = TCP_TTL;

-       if (ip_output(m, tp->t_ipopt) == 0)
-               return (0);
+       if (error = ip_output(m, tp->t_ipopt, (so->so_options & SO_DONTROUTE) ?
+           &routetoif : &tp->t_inpcb->inp_route, 0))
+               return (error);

 
        /*
         * Data sent (as far as we can tell).
         * If this advertises a larger window than any other segment,
 
        /*
         * Data sent (as far as we can tell).
         * If this advertises a larger window than any other segment,

-        * then record its sequence to be used in suppressing messages.
+        * then remember the size of the advertised window.

         * Drop send for purpose of ACK requirements.
         */
        if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv))
                tp->rcv_adv = tp->rcv_nxt + win;
        tp->t_flags &= ~(TF_ACKNOW|TF_DELACK);
         * Drop send for purpose of ACK requirements.
         */
        if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv))
                tp->rcv_adv = tp->rcv_nxt + win;
        tp->t_flags &= ~(TF_ACKNOW|TF_DELACK);

-       tp->snd_max = tp->snd_nxt;
-       return (1);
+       if (sendalot && tp->t_force == 0)
+               goto again;
+       return (0);
+}
+
+tcp_setpersist(tp)
+       register struct tcpcb *tp;
+{
+
+       if (tp->t_timer[TCPT_REXMT])
+               panic("tcp_output REXMT");
+       /*
+        * Start/restart persistance timer.
+        */
+       TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
+           ((int)(tcp_beta * tp->t_srtt)) << tp->t_rxtshift,
+           TCPTV_PERSMIN, TCPTV_MAX);
+       tp->t_rxtshift++;
+       if (tp->t_rxtshift >= TCP_MAXRXTSHIFT)
+               tp->t_rxtshift = 0;

 }
 }