#include "u.h"
#include "lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include "errno.h"
enum {
MSrexmit= 1000,
Nmask= 0x7,
};
#define DPRINT /*if(q->flag&QDEBUG)kprint*/
typedef struct Urp Urp;
#define NOW (MACHP(0)->ticks*MS2HZ)
/*
* URP status
*/
struct urpstat {
ulong input; /* bytes read from urp */
ulong output; /* bytes output to urp */
ulong rxmit; /* retransmit rejected urp msg */
ulong rjtrs; /* reject, trailer size */
ulong rjpks; /* reject, packet size */
ulong rjseq; /* reject, sequence number */
ulong levelb; /* unknown level b */
ulong enqsx; /* enqs sent */
ulong enqsr; /* enqs rcved */
} urpstat;
struct Urp {
QLock;
short state; /* flags */
Rendez r; /* process waiting for close */
/* input */
QLock ack; /* ack lock */
Queue *rq; /* input queue */
uchar iseq; /* last good input sequence number */
uchar lastecho; /* last echo/rej sent */
uchar trbuf[3]; /* trailer being collected */
short trx; /* # bytes in trailer being collected */
int blocks;
/* output */
QLock xmit; /* output lock, only one process at a time */
Queue *wq; /* output queue */
int maxout; /* maximum outstanding unacked blocks */
int maxblock; /* max block size */
int next; /* next block to send */
int unechoed; /* first unechoed block */
int unacked; /* first unacked block */
int nxb; /* next xb to use */
Block *xb[8]; /* the xmit window buffer */
QLock xl[8];
ulong timer; /* timeout for xmit */
int rexmit;
int kstarted;
};
#define WINDOW(u) ((u)->unechoed>(u)->next ? (u)->unechoed+(u)->maxout-(u)->next-8 :\
(u)->unechoed+(u)->maxout-(u)->next)
#define IN(x, f, n) (f<=n ? (x>=f && x<n) : (x<n || x>=f))
#define NEXT(x) (((x)+1)&Nmask)
/*
* Protocol control bytes
*/
#define SEQ 0010 /* sequence number, ends trailers */
#undef ECHO
#define ECHO 0020 /* echos, data given to next queue */
#define REJ 0030 /* rejections, transmission error */
#define ACK 0040 /* acknowledgments */
#define BOT 0050 /* beginning of trailer */
#define BOTM 0051 /* beginning of trailer, more data follows */
#define BOTS 0052 /* seq update algorithm on this trailer */
#define SOU 0053 /* start of unsequenced trailer */
#define EOU 0054 /* end of unsequenced trailer */
#define ENQ 0055 /* xmitter requests flow/error status */
#define CHECK 0056 /* xmitter requests error status */
#define INITREQ 0057 /* request initialization */
#define INIT0 0060 /* disable trailer processing */
#define INIT1 0061 /* enable trailer procesing */
#define AINIT 0062 /* response to INIT0/INIT1 */
#undef DELAY
#define DELAY 0100 /* real-time printing delay */
#define BREAK 0110 /* Send/receive break (new style) */
#define REJECTING 0x1
#define INITING 0x2
#define HUNGUP 0x4
#define OPEN 0x8
#define CLOSING 0x10
Urp *urp;
/*
* predeclared
*/
static void urpciput(Queue*, Block*);
static void urpiput(Queue*, Block*);
static void urpoput(Queue*, Block*);
static void urpopen(Queue*, Stream*);
static void urpclose(Queue *);
static void output(Urp*);
static void sendblock(Urp*, int);
static void rcvack(Urp*, int);
static void flushinput(Urp*);
static void sendctl(Urp*, int);
static void sendack(Urp*);
static void sendrej(Urp*);
static void initoutput(Urp*, int);
static void initinput(Urp*, int);
static void urpkproc(void *arg);
static void urptimer(Alarm*);
static void urpvomit(char*, Urp*);
Qinfo urpinfo = { urpciput, urpoput, urpopen, urpclose, "urp" };
void
urpreset(void)
{
newqinfo(&urpinfo);
urp = (Urp *)ialloc(conf.nurp*sizeof(Urp), 0);
alarm(500, urptimer, 0);
}
static void
urpopen(Queue *q, Stream *s)
{
Urp *up;
int i;
char name[128];
/*
* find a free urp structure
*/
for(up = urp; up < &urp[conf.nurp]; up++){
qlock(up);
if(up->state == 0)
break;
qunlock(up);
}
if(up == &urp[conf.nurp]){
q->ptr = 0;
WR(q)->ptr = 0;
error(0, Egreg);
}
q->ptr = q->other->ptr = up;
up->rq = q;
up->wq = q->other;
up->state = OPEN;
qunlock(up);
initinput(up, 0);
initoutput(up, 0);
/*
* start the ack/(re)xmit process
*/
sprint(name, "urp%d", up - urp);
kproc(name, urpkproc, up);
}
/*
* Shut down the connection and kill off the kernel process
*/
static int
isdead(void *a)
{
Urp *up;
up = (Urp *)a;
return up->kstarted==0;
}
static int
isflushed(void *a)
{
Urp *up;
up = (Urp *)a;
return (up->state&HUNGUP) || (up->unechoed==up->nxb && up->wq->len==0);
}
static void
urpclose(Queue *q)
{
Block *bp;
Urp *up;
int i;
up = (Urp *)q->ptr;
if(up == 0)
return;
/*
* wait for all outstanding messages to drain, tell kernel
* process we're closing.
*
* if 2 minutes elapse, give it up
*/
up->state |= CLOSING;
tsleep(&up->r, isflushed, up, 2*60*1000);
/*
* tell kernel process to die
*/
up->state |= HUNGUP;
wakeup(&up->rq->r);
qlock(&up->xmit);
/*
* ack all outstanding messages
*/
i = up->next - 1;
if(i < 0)
i = 7;
rcvack(up, ECHO+i);
/*
* free all staged but unsent messages
*/
for(i = 0; i < 7; i++)
if(up->xb[i]){
freeb(up->xb[i]);
up->xb[i] = 0;
}
qunlock(&up->xmit);
/*
* wait for kernel process to die
*/
while(up->kstarted)
sleep(&up->r, isdead, up);
up->state = 0;
}
/*
* upstream control messages
*/
static void
urpctliput(Urp *up, Queue *q, Block *bp)
{
switch(bp->type){
case M_HANGUP:
up->state |= HUNGUP;
wakeup(&up->r);
wakeup(&up->rq->r);
break;
}
PUTNEXT(q, bp);
}
/*
* character mode input.
*
* the first byte in every message is a ctl byte (which belongs at the end).
*/
void
urpciput(Queue *q, Block *bp)
{
Urp *up;
int i;
int ctl;
up = (Urp *)q->ptr;
if(bp->type != M_DATA){
urpctliput(up, q, bp);
return;
}
/*
* get the control character
*/
ctl = *bp->rptr++;
if(ctl < 0)
return;
/*
* take care of any data
*/
if(BLEN(bp)>0 && q->next->len<2*Streamhi && q->next->nb<2*Streambhi){
bp->flags |= S_DELIM;
PUTNEXT(q, bp);
} else
freeb(bp);
/*
* handle the control character
*/
switch(ctl){
case 0:
break;
case ENQ:
urpstat.enqsr++;
sendctl(up, up->lastecho);
sendctl(up, ACK+up->iseq);
break;
case CHECK:
sendctl(up, ACK+up->iseq);
break;
case AINIT:
up->state &= ~INITING;
flushinput(up);
wakeup(&up->rq->r);
break;
case INIT0:
case INIT1:
sendctl(up, AINIT);
if(ctl == INIT1)
q->put = urpiput;
initinput(up, 0);
break;
case INITREQ:
initoutput(up, 0);
break;
case BREAK:
break;
case REJ+0: case REJ+1: case REJ+2: case REJ+3:
case REJ+4: case REJ+5: case REJ+6: case REJ+7:
rcvack(up, ctl);
break;
case ACK+0: case ACK+1: case ACK+2: case ACK+3:
case ACK+4: case ACK+5: case ACK+6: case ACK+7:
case ECHO+0: case ECHO+1: case ECHO+2: case ECHO+3:
case ECHO+4: case ECHO+5: case ECHO+6: case ECHO+7:
rcvack(up, ctl);
break;
case SEQ+0: case SEQ+1: case SEQ+2: case SEQ+3:
case SEQ+4: case SEQ+5: case SEQ+6: case SEQ+7:
qlock(&up->ack);
i = ctl & Nmask;
if(!QFULL(q->next))
sendctl(up, up->lastecho = ECHO+i);
up->iseq = i;
qunlock(&up->ack);
break;
}
}
/*
* block mode input.
*
* the first byte in every message is a ctl byte (which belongs at the end).
*
* Simplifying assumption: one put == one message && the control byte
* is in the first block. If this isn't true, strange bytes will be
* used as control bytes.
*/
void
urpiput(Queue *q, Block *bp)
{
Urp *up;
int i;
int ctl;
up = (Urp *)q->ptr;
if(bp->type != M_DATA){
urpctliput(up, q, bp);
return;
}
/*
* get the control character
*/
ctl = *bp->rptr++;
/*
* take care of any block count(trx)
*/
while(up->trx){
if(BLEN(bp)<=0)
break;
switch (up->trx) {
case 1:
case 2:
up->trbuf[up->trx++] = *bp->rptr++;
continue;
default:
up->trx = 0;
break;
}
}
/*
* queue the block(s)
*/
if(BLEN(bp) > 0){
bp->flags &= ~S_DELIM;
putq(q, bp);
if(q->len > 4*1024){
flushinput(up);
return;
}
} else
freeb(bp);
/*
* handle the control character
*/
switch(ctl){
case 0:
break;
case ENQ:
DPRINT("rENQ %d %uo %uo\n", up->blocks, up->lastecho, ACK+up->iseq);
up->blocks = 0;
urpstat.enqsr++;
sendctl(up, up->lastecho);
sendctl(up, ACK+up->iseq);
flushinput(up);
break;
case CHECK:
sendctl(up, ACK+up->iseq);
break;
case AINIT:
up->state &= ~INITING;
flushinput(up);
wakeup(&up->rq->r);
break;
case INIT0:
case INIT1:
sendctl(up, AINIT);
if(ctl == INIT0)
q->put = urpciput;
initinput(up, 0);
break;
case INITREQ:
initoutput(up, 0);
break;
case BREAK:
break;
case BOT:
case BOTM:
case BOTS:
DPRINT("rBOT%d...", ctl-BOT);
up->trx = 1;
up->trbuf[0] = ctl;
break;
case REJ+0: case REJ+1: case REJ+2: case REJ+3:
case REJ+4: case REJ+5: case REJ+6: case REJ+7:
DPRINT("rREJ\n");
rcvack(up, ctl);
break;
case ACK+0: case ACK+1: case ACK+2: case ACK+3:
case ACK+4: case ACK+5: case ACK+6: case ACK+7:
case ECHO+0: case ECHO+1: case ECHO+2: case ECHO+3:
case ECHO+4: case ECHO+5: case ECHO+6: case ECHO+7:
rcvack(up, ctl);
break;
/*
* if the sequence number is the next expected
* and the trailer length == 3
* and the block count matches the bytes received
* then send the bytes upstream.
*/
case SEQ+0: case SEQ+1: case SEQ+2: case SEQ+3:
case SEQ+4: case SEQ+5: case SEQ+6: case SEQ+7:
i = ctl & Nmask;
if(up->trx != 3){
urpstat.rjtrs++;
sendrej(up);
break;
} else if(q->len != up->trbuf[1] + (up->trbuf[2]<<8)){
urpstat.rjpks++;
sendrej(up);
break;
} else if(i != ((up->iseq+1)&Nmask)) {
urpstat.rjseq++;
sendrej(up);
break;
} else if(q->next->len > (3*Streamhi)/2
|| q->next->nb > (3*Streambhi)/2) {
flushinput(up);
break;
}
DPRINT("rSEQ%d accept %d\n", i, q->len);
/*
* send data upstream
*/
if(q->first) {
if(up->trbuf[0] != BOTM)
q->last->flags |= S_DELIM;
while(bp = getq(q))
PUTNEXT(q, bp);
} else {
bp = allocb(0);
if(up->trbuf[0] != BOTM)
bp->flags |= S_DELIM;
PUTNEXT(q, bp);
}
up->trx = 0;
/*
* acknowledge receipt
*/
qlock(&up->ack);
up->iseq = i;
if(!QFULL(q->next))
sendctl(up, up->lastecho = ECHO|i);
qunlock(&up->ack);
break;
}
}
/*
* downstream control
*/
static void
urpctloput(Urp *up, Queue *q, Block *bp)
{
char *fields[2];
int n;
int inwin=0, outwin=0;
switch(bp->type){
case M_CTL:
if(streamparse("init", bp)){
switch(getfields((char *)bp->rptr, fields, 2, ' ')){
case 2:
inwin = strtoul(fields[1], 0, 0);
case 1:
outwin = strtoul(fields[0], 0, 0);
}
/* initinput(up, inwin); */
initoutput(up, outwin);
freeb(bp);
return;
}
if(streamparse("debug", bp)){
switch(getfields((char *)bp->rptr, fields, 2, ' ')){
case 1:
if (strcmp(fields[0], "on") == 0) {
q->flag |= QDEBUG;
q->other->flag |= QDEBUG;
}
if (strcmp(fields[0], "off") == 0) {
q->flag &= ~QDEBUG;
q->other->flag &= ~QDEBUG;
}
}
freeb(bp);
return;
}
}
PUTNEXT(q, bp);
}
/*
* accept data from a writer
*/
static void
urpoput(Queue *q, Block *bp)
{
Urp *up;
up = (Urp *)q->ptr;
if(bp->type != M_DATA){
urpctloput(up, q, bp);
return;
}
urpstat.output += BLEN(bp);
putq(q, bp);
output(up);
}
/*
* start output
*/
static void
output(Urp *up)
{
Block *bp, *nbp;
ulong now;
Queue *q;
int n;
int i;
if(!canqlock(&up->xmit))
return;
if(waserror()){
print("urp output error\n");
qunlock(&up->xmit);
nexterror();
}
/*
* if still initing and it's time to rexmit, send an INIT1
*/
now = NOW;
if(up->state & INITING){
if(now > up->timer){
sendctl(up, INIT1);
up->timer = now + MSrexmit;
}
goto out;
}
/*
* fill the transmit buffers, `nxb' can never overtake `unechoed'
*/
q = up->wq;
i = NEXT(up->nxb);
if(i != up->unechoed) {
for(bp = getq(q); bp && i!=up->unechoed; i = NEXT(i)){
if(up->xb[up->nxb] != 0)
urpvomit("output", up);
if(BLEN(bp) > up->maxblock){
nbp = up->xb[up->nxb] = allocb(0);
nbp->rptr = bp->rptr;
nbp->wptr = bp->rptr = bp->rptr + up->maxblock;
} else {
up->xb[up->nxb] = bp;
bp = getq(q);
}
up->nxb = i;
}
if(bp)
putbq(q, bp);
}
/*
* retransmit cruft
*/
if(up->rexmit){
/*
* if a retransmit is requested, move next back to
* the unacked blocks
*/
up->rexmit = 0;
up->next = up->unacked;
} else if(up->unacked!=up->next && NOW>up->timer){
/*
* if a retransmit time has elapsed since a transmit,
* send an ENQ
*/
up->timer = NOW + MSrexmit;
up->state &= ~REJECTING;
sendctl(up, ENQ);
goto out;
}
/*
* if there's a window open, push some blocks out
*
* the lock is to synchronize with acknowledges that free
* blocks.
*/
while(WINDOW(up)>0 && up->next!=up->nxb){
i = up->next;
qlock(&up->xl[i]);
if(waserror()){
qunlock(&up->xl[i]);
nexterror();
}
sendblock(up, i);
qunlock(&up->xl[i]);
up->next = NEXT(up->next);
poperror();
}
out:
qunlock(&up->xmit);
poperror();
}
/*
* send a control byte, put the byte at the end of the allocated
* space in case a lower layer needs header room.
*/
static void
sendctl(Urp *up, int ctl)
{
Block *bp;
if(QFULL(up->wq->next))
return;
bp = allocb(1);
bp->wptr = bp->lim;
bp->rptr = bp->lim-1;
*bp->rptr = ctl;
bp->flags |= S_DELIM;
PUTNEXT(up->wq, bp);
}
/*
* send a reject
*/
static void
sendrej(Urp *up)
{
Queue *q = up->wq;
flushinput(up);
qlock(&up->ack);
if((up->lastecho&~Nmask) == ECHO){
DPRINT("REJ %d\n", up->iseq);
sendctl(up, up->lastecho = REJ|up->iseq);
}
qunlock(&up->ack);
}
/*
* send an acknowledge
*/
static void
sendack(Urp *up)
{
Block *bp;
/*
* check the precondition for acking
*/
if(QFULL(up->rq->next) || (up->lastecho&Nmask)==up->iseq)
return;
if(!canqlock(&up->ack))
return;
/*
* check again now that we've locked
*/
if(QFULL(up->rq->next) || (up->lastecho&Nmask)==up->iseq){
qunlock(&up->ack);
return;
}
/*
* send the ack
*/
sendctl(up, up->lastecho = ECHO|up->iseq);
qunlock(&up->ack);
}
/*
* send a block.
*/
static void
sendblock(Urp *up, int bn)
{
Block *bp, *m, *nbp;
int n;
up->timer = NOW + MSrexmit;
if(QFULL(up->wq->next))
return;
/*
* message 1, the BOT and the data
*/
bp = up->xb[bn];
if(bp == 0){
urpvomit("sendblock", up);
return;
}
m = allocb(1);
m->rptr = m->lim - 1;
m->wptr = m->lim;
*m->rptr = (bp->flags & S_DELIM) ? BOT : BOTM;
nbp = m->next = allocb(0);
nbp->rptr = bp->rptr;
nbp->wptr = bp->wptr;
nbp->flags |= S_DELIM;
PUTNEXT(up->wq, m);
/*
* message 2, the block length and the SEQ
*/
m = allocb(3);
m->rptr = m->lim - 3;
m->wptr = m->lim;
n = BLEN(bp);
m->rptr[0] = SEQ | bn;
m->rptr[1] = n;
m->rptr[2] = n<<8;
m->flags |= S_DELIM;
PUTNEXT(up->wq, m);
}
/*
* receive an acknowledgement
*/
static void
rcvack(Urp *up, int msg)
{
int seqno;
int next;
int i;
seqno = msg&Nmask;
next = NEXT(seqno);
/*
* release any acknowledged blocks
*/
if(IN(seqno, up->unacked, up->next)){
for(; up->unacked != next; up->unacked = NEXT(up->unacked)){
i = up->unacked;
qlock(&up->xl[i]);
if(up->xb[i])
freeb(up->xb[i]);
else
urpvomit("rcvack", up);
up->xb[i] = 0;
qunlock(&up->xl[i]);
}
}
switch(msg & 0370){
case ECHO:
if(IN(seqno, up->unechoed, up->next)) {
up->unechoed = next;
}
/*
* the next reject at the start of a window starts a
* retransmission.
*/
up->state &= ~REJECTING;
break;
case REJ:
if(IN(seqno, up->unechoed, up->next))
up->unechoed = next;
/*
* ... FALL THROUGH ...
*/
case ACK:
/*
* start a retransmission if we aren't retransmitting
* and this is the start of a window.
*/
if(up->unechoed==next && !(up->state & REJECTING)){
up->state |= REJECTING;
up->rexmit = 1;
}
break;
}
wakeup(&up->rq->r);
}
/*
* throw away any partially collected input
*/
static void
flushinput(Urp *up)
{
Block *bp;
while (bp = getq(up->rq))
freeb(bp);
up->trx = 0;
}
/*
* initialize output
*/
static void
initoutput(Urp *up, int window)
{
int i;
/*
* set output window
*/
up->maxblock = window/4;
if(up->maxblock < 64)
up->maxblock = 64;
up->maxblock -= 4;
up->maxout = 3;
/*
* set sequence varialbles
*/
up->unechoed = 1;
up->unacked = 1;
up->next = 1;
up->nxb = 1;
up->rexmit = 0;
/*
* free any outstanding blocks
*/
for(i = 0; i < 8; i++){
qlock(&up->xl[i]);
if(up->xb[i])
freeb(up->xb[i]);
up->xb[i] = 0;
qunlock(&up->xl[i]);
}
/*
* tell the other side we've inited
*/
up->state |= INITING;
up->timer = NOW + MSrexmit;
sendctl(up, INIT1);
}
/*
* initialize input
*/
static void
initinput(Urp *up, int window)
{
/*
* restart all sequence parameters
*/
up->blocks = 0;
up->trx = 0;
up->iseq = 0;
up->lastecho = ECHO+0;
flushinput(up);
}
/*
* do retransmissions etc
*/
static int
todo(void *arg)
{
Urp *up;
up = (Urp *)arg;
return (up->state&INITING)
? NOW>up->timer /* time to INIT1 */
: ((up->unacked!=up->next && NOW>up->timer) /* time to ENQ */
|| (!QFULL(up->rq->next) && up->iseq!=(up->lastecho&7))); /* time to ECHO */
}
static void
urpkproc(void *arg)
{
Urp *up;
up = (Urp *)arg;
up->kstarted = 1;
if(waserror()){
print("urpkproc error %ux\n", up);
up->kstarted = 0;
wakeup(&up->r);
return;
}
for(;;){
if(up->state & HUNGUP)
break;
if(!QFULL(up->rq->next))
sendack(up);
output(up);
sleep(&up->rq->r, todo, up);
}
up->kstarted = 0;
wakeup(&up->r);
poperror();
}
/*
* timer to wakeup urpkproc's for retransmissions
*/
static void
urptimer(Alarm *a)
{
Urp *up;
Urp *last;
Queue *q;
cancel(a);
alarm(500, urptimer, 0);
for(up = urp, last = &urp[conf.nurp]; up < last; up++){
if(up->state==0)
continue;
if(up->rq && todo(up))
wakeup(&up->rq->r);
}
}
/*
* urp got very confused, complain
*/
static void
urpvomit(char *msg, Urp* up)
{
print("urpvomit: %s %ux next %d unechoed %d unacked %d nxb %d\n",
msg, up, up->next, up->unechoed, up->unacked, up->nxb);
print("\txb: %ux %ux %ux %ux %ux %ux %ux %ux\n",
up->xb[0], up->xb[1], up->xb[2], up->xb[3], up->xb[4],
up->xb[5], up->xb[6], up->xb[7]);
print("\tiseq: %uo lastecho: %uo trx: %d trbuf: %uo %uo %uo\n",
up->iseq, up->lastecho, up->trx, up->trbuf[0], up->trbuf[1],
up->trbuf[2]);
print("\tupq: %ux %d %d\n", &up->rq->next->r, up->rq->next->nb,
up->rq->next->len);
}
int
urpdump(void)
{
Urp *up;
for(up = urp; up < &urp[conf.nurp]; up++)
if(up->rq)
urpvomit("", up);
}