-/* tcp_output.c 4.35 82/03/20 */
+/* tcp_output.c 4.46 82/10/09 */
#include "../h/param.h"
#include "../h/systm.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
-#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 "../net/tcp_debug.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: indicate max segment length 1/2 of space
- * allocated for receive; if TCPTRUEOOB is defined, indicate
- * willingness to do true out-of-band.
+ * Initial options.
*/
-#ifndef TCPTRUEOOB
u_char tcp_initopt[4] = { TCPOPT_MAXSEG, 4, 0x0, 0x0, };
-#else
-u_char tcp_initopt[6] = { TCPOPT_MAXSEG, 4, 0x0, 0x0, TCPOPT_WILLOOB, 2 };
-#endif
/*
* Tcp output routine: figure out what should be sent and send it.
register struct socket *so = tp->t_inpcb->inp_socket;
register int len;
struct mbuf *m0;
- int off, flags, win;
+ int off, flags, win, error;
register struct mbuf *m;
register struct tcpiphdr *ti;
u_char *opt;
unsigned optlen = 0;
+ int sendalot;
-COUNT(TCP_OUTPUT);
/*
* Determine length of data that should be transmitted,
* 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;
if (len < 0)
- return (0); /* past FIN */
- if (len > tp->t_maxseg)
+ return (0); /* ??? */ /* past FIN */
+ if (len > tp->t_maxseg) {
len = tp->t_maxseg;
+ sendalot = 1;
+ }
flags = tcp_outflags[tp->t_state];
if (tp->snd_nxt + len < tp->snd_una + so->so_snd.sb_cc)
if (tp->t_flags&TF_ACKNOW)
goto send;
-#ifdef TCPTRUEOOB
- /*
- * Send if an out of band data or ack should be transmitted.
- */
- if (tp->t_oobflags&(TCPOOB_OWEACK|TCPOOB_NEEDACK)))
- goto send;
-#endif
/*
* Calculate available window in i, and also amount
((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.
*/
*/
MGET(m, 0);
if (m == 0)
- return (0);
+ return (ENOBUFS);
m->m_off = MMAXOFF - sizeof (struct tcpiphdr);
m->m_len = sizeof (struct tcpiphdr);
if (len) {
goto noopt;
opt = tcp_initopt;
optlen = sizeof (tcp_initopt);
- *(u_short *)(opt + 2) = so->so_rcv.sb_hiwat / 2;
+ *(u_short *)(opt + 2) = MIN(so->so_rcv.sb_hiwat / 2, 1024);
#if vax
*(u_short *)(opt + 2) = htons(*(u_short *)(opt + 2));
#endif
opt = mtod(tp->t_tcpopt, u_char *);
optlen = tp->t_tcpopt->m_len;
}
-#ifndef TCPTRUEOOB
- if (opt)
-#else
- if (opt || (tp->t_oobflags&(TCPOOB_OWEACK|TCPOOB_NEEDACK)))
-#endif
- {
+ if (opt) {
m0 = m->m_next;
m->m_next = m_get(M_DONTWAIT);
if (m->m_next == 0) {
(void) m_free(m);
m_freem(m0);
- return (0);
+ return (ENOBUFS);
}
m->m_next->m_next = m0;
m0 = m->m_next;
- m0->m_off = MMINOFF;
m0->m_len = optlen;
bcopy((caddr_t)opt, mtod(m0, caddr_t), optlen);
opt = (u_char *)(mtod(m0, caddr_t) + optlen);
-#ifdef TCPTRUEOOB
- if (tp->t_oobflags&TCPOOB_OWEACK) {
-printf("tp %x send OOBACK for %x\n", tp->t_iobseq);
- *opt++ = TCPOPT_OOBACK;
- *opt++ = 3;
- *opt++ = tp->t_iobseq;
- m0->m_len += 3;
- tp->t_oobflags &= ~TCPOOB_OWEACK;
- /* sender should rexmt oob to force ack repeat */
- }
- if (tp->t_oobflags&TCPOOB_NEEDACK) {
-printf("tp %x send OOBDATA seq %x data %x\n", tp->t_oobseq, tp->t_oobc);
- *opt++ = TCPOPT_OOBDATA;
- *opt++ = 8;
- *opt++ = tp->t_oobseq;
- *opt++ = tp->t_oobc;
- *(tcp_seq *)opt = tp->t_oobmark - tp->snd_nxt;
-#ifdef vax
- *(tcp_seq *)opt = htonl((unsigned)*(tcp_seq *)opt);
-#endif
- m0->m_len += 8;
- TCPT_RANGESET(tp->t_timer[TCPT_OOBREXMT],
- tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX);
- }
-#endif
while (m0->m_len & 0x3) {
*opt++ = TCPOPT_EOL;
m0->m_len++;
* 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
ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + (int)optlen + len);
/*
- * Advance snd_nxt over sequence space of this segment
- */
- if (flags & (TH_SYN|TH_FIN))
- tp->snd_nxt++;
- tp->snd_nxt += len;
-
- /*
- * If this transmission closes the window,
- * start persistance timer at 2 round trip times
- * but at least TCPTV_PERSMIN ticks.
+ * In transmit state, time the transmission and arrange for
+ * the retransmit. In persist state, reset persist time for
+ * next persist.
*/
- if (TCPS_HAVERCVDSYN(tp->t_state) &&
- SEQ_GEQ(tp->snd_nxt, tp->snd_una+tp->snd_wnd) &&
- tp->t_timer[TCPT_PERSIST] == 0)
- TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
- 2 * tp->t_srtt, TCPTV_PERSMIN, TCPTV_MAX);
+ 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;
- /*
- * 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;
+ /*
+ * 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;
}
/*
* Trace.
*/
- if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
+ if (so->so_options & SO_DEBUG)
tcp_trace(TA_OUTPUT, tp->t_state, tp, ti, 0);
/*
*/
((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + optlen + len;
((struct ip *)ti)->ip_ttl = TCP_TTL;
- if (ip_output(m, tp->t_ipopt, 0) == 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 (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);
- if (SEQ_GT(tp->snd_nxt, tp->snd_max))
- 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;
}