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<a href="/plan9/">Plan 9 from Bell Labs</a>’s /usr/web/sources/contrib/vsrinivas/vtrc.c


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Copyright © 2009 Alcatel-Lucent. 
Distributed under the
<a href="/plan9/license.html">Lucent Public License version 1.02</a>.
 
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/*
* Reconnecting Venti proxy
*
* Proxies requests to a remove Venti; if the connection to a remove server
* fails, it keeps retrying the request till a connection can be reestablished
*
* Usage:
* vtrc -a listenaddress -h hostventi [-v]
* vtrc listens on listenaddress, proxying connections to hostventi
*
* based on Russ Cox's venti/ro.c
*/

#include <u.h>
#include <libc.h>
#include <venti.h>
#include <libsec.h>
#include <avl.h>

#ifndef _UNISTD_H_
#pragma varargck type "F" VtFcall*
#pragma varargck type "T" void
#endif

char *za = nil;
VtConn *z =nil;
int verbose;
QLock vtconnlock;

enum
{
STACK = 4096
};

/* called with the vtconnlock held */
void try_reconnect(void) {
if (z != nil)
vtfreeconn(z);
z = vtdial(za);
if (z != nil)
vtconnect(z);
}

void
usage(void)
{
fprint(2, "usage: vtrc [-v] [-a address] [-h address]\n");
exits("usage");
}

void
readthread(void *v)
{
char err[ERRMAX];
VtReq *r;
uchar *buf;
int n = -1;

r = v;
buf = vtmalloc(r->tx.count);

qlock(&vtconnlock); for (;;) {
n = -1;
if (z != nil)
n = vtread(z, r->tx.score, r->tx.blocktype, buf, r->tx.count);

if (n < 0)
try_reconnect();
else
break;
} qunlock(&vtconnlock);

r->rx.data = packetforeign(buf, n, free, buf);

vtrespond(r);
}

void
writethread(void *v) {
VtReq *r;
int n = -1;

r = v;

packetsha1(r->tx.data, r->rx.score);

qlock(&vtconnlock); for (;;) {
n = -1;
if (z != nil)
n = vtwritepacket(z, r->rx.score, r->tx.blocktype, r->tx.data);

if (n < 0)
try_reconnect();
else
break;
} qunlock(&vtconnlock);

vtrespond(r);
}

VtSrv *srv;

void
coreproc(void *v) {
VtReq *r1;

while((r1 = vtgetreq(srv)) != nil){
r1->rx.msgtype = r1->tx.msgtype+1;
if(verbose)
fprint(2, "<- %F\n", &r1->tx);
switch(r1->tx.msgtype){
case VtTping:
vtrespond(r1);
break;
case VtTgoodbye:
vtrespond(r1);
break;
case VtTread:
proccreate(readthread, r1, 16384);
continue;
case VtTwrite:
proccreate(writethread, r1, 16384);
continue;
case VtTsync:
vtrespond(r1);
break;
}
if(verbose)
fprint(2, "-> %F\n", &r1->rx);
}
}

void
threadmain(int argc, char **argv)
{
char *address, *ventiaddress;

fmtinstall('F', vtfcallfmt);
fmtinstall('V', vtscorefmt);

address = "tcp!*!venti";
ventiaddress = nil;

ARGBEGIN{
case 'v':
verbose++;
break;
case 'a':
address = EARGF(usage());
break;
case 'h':
ventiaddress = EARGF(usage());
break;
default:
usage();
}ARGEND

if((z = vtdial(ventiaddress)) == nil)
sysfatal("vtdial %s: %r", ventiaddress);
if(vtconnect(z) < 0)
sysfatal("vtconnect: %r");

za = ventiaddress;
if (za == nil)
sysfatal("no remote address");

srv = vtlisten(address);
if(srv == nil)
sysfatal("vtlisten %s: %r", address);

print("vtrc: Ice Nine, Baby\n");

rfork(RFNOTEG);
proccreate(coreproc, nil, 4096*16);

exits(nil);
}


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