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<title>/usr/web/sources/contrib/cinap_lenrek/torrent.c - Plan 9 from Bell Labs</title>


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


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Copyright © 2009 Alcatel-Lucent. 
Distributed under the
<a href="/plan9/license.html">Lucent Public License version 1.02</a>.
 
<a href="/plan9/download.html">Download the Plan 9 distribution.</a>

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#include <u.h>
#include <libc.h>
#include <mp.h>
#include <libsec.h>

typedef struct Dict Dict;
typedef struct Piece Piece;
typedef struct File File;
typedef struct Stats Stats;

struct Dict
{
Dict *val;
Dict *next;
char *start, *end;
int len;
char typ; // i, d, s, l
char str[];
};

struct Piece
{
uchar *hash;
int len;
int brk;
};

struct File
{
File *next;
char *name;
int fd;
vlong off;
vlong len;
};

struct Stats
{
Lock;
vlong up;
vlong down;
vlong left;
};

enum {
MAXIO = 16*1024,
SRVPROCS = 16,
CLIPROCS = 16,
};

int debug;
int killgroup = -1;
int port = 6881;
char *deftrack = "http://exodus.desync.com/announce";
char *mntweb = "/mnt/web";
uchar infohash[20];
uchar peerid[20];
int blocksize;

int npieces;
Piece *pieces;

int nhavemap;
uchar *havemap;
int nhavepieces;

File *files;
Stats stats;

int
finished(void)
{
return nhavepieces >= npieces;
}

void
freedict(Dict *d)
{
if(d){
if(d->val != d)
freedict(d->val);
freedict(d->next);
free(d);
}
}

char*
bparse(char *s, char *e, Dict **dp)
{
char *x, t;
Dict *d;
int n;

*dp = nil;
if(s >= e)
return e;

t = *s;
switch(t){
case 'd':
case 'l':
x = s++;
d = nil;
while(s < e){
if(*s == 'e'){
s++;
break;
}
if(t == 'd'){
s = bparse(s, e, dp);
if((d = *dp) == nil)
break;
} else
d = *dp = mallocz(sizeof(*d), 1);
d->typ = t;
d->start = x;
if(s < e){
s = bparse(s, e, &d->val);
dp = &d->next;
d->end = s;
}
x = s;
}
if(d)
d->end = s;
return s;
case 'i':
x = ++s;
if((s = memchr(x, 'e', e - x)) == nil)
return e;
n = s - x;
s++;
break;
default:
if((x = memchr(s, ':', e - s)) == nil)
return e;
x++;
if((n = atoi(s)) < 0)
return e;
s = x + n;
if((s > e) || (s < x)){
n = e - x;
s = e;
}
t = 's';
}
d = mallocz(sizeof(*d) + n+1, 1);
d->typ = t;
memmove(d->str, x, d->len = n);
d->str[n] = 0;
*dp = d;
return s;
}

char*
dstr(Dict *d)
{
if(d && (d->typ == 's' || d->typ == 'i'))
return d->str;
return nil;
}

Dict*
dlook(Dict *d, char *s)
{
for(; d && d->typ == 'd'; d = d->next)
if(d->len && strcmp(d->str, s) == 0)
return d->val;
return nil;
}

int
readall(int fd, char **p)
{
int n, r;

n = 0;
*p = nil;
while(*p = realloc(*p, n+1024)){
if((r = read(fd, *p+n, 1024)) <= 0)
break;
n += r;
}
return n;
}

int
rwpiece(int wr, int index, uchar *data, int len, int poff)
{
vlong off;
int n, m;
File *f;

if(len <= 0 || poff >= pieces[index].len)
return 0;
if(len+poff > pieces[index].len)
len = pieces[index].len - poff;
off = (vlong)index * blocksize;
off += poff;
for(f = files; f; f = f->next)
if((f->off+f->len) > off)
break;
off -= f->off;
n = ((off + len) > f->len) ? f->len - off : len;
if((n = (wr ? pwrite(f->fd, data, n, off) : pread(f->fd, data, n, off))) <= 0)
return -1;
if((m = rwpiece(wr, index, data + n, len - n, poff + n)) < 0)
return -1;
return n+m;
}

int
havepiece(int x)
{
uchar *p, m, hash[20];
int n;

m = 0x80>>(x&7);
if(havemap[x>>3] & m)
return 1;
p = malloc(blocksize);
n = pieces[x].len;
if(rwpiece(0, x, p, n, 0) != n){
free(p);
return 0;
}
sha1(p, n, hash, nil);
free(p);
if(memcmp(hash, pieces[x].hash, 20))
return 0;
lock(&stats);
if((havemap[x>>3] & m) == 0){
havemap[x>>3] |= m;
nhavepieces++;
stats.left -= pieces[x].len;
}
unlock(&stats);
return 1;
}

int
pickpiece(uchar *map)
{
int i, x, r, k;
uchar m;

r = -1;
k = 0;
for(i = 0; i<nhavemap; i++){
if(map[i] == 0)
continue;
for(x = i<<3, m = 0x80; m; m >>= 1, x++){
if((~map[i] | havemap[i]) & m)
continue;
if(nrand(++k) == 0)
r = x;
}
}
return r;
}

int
unpack(uchar *s, int n, char *fmt, ...)
{
va_list arg;
uchar *b, *e;

b = s;
e = b + n;
va_start(arg, fmt);
for(; *fmt; fmt++) {
switch(*fmt){
case '_':
s++;
break;
case 'b':
if(s+1 > e) goto Err;
*va_arg(arg, int*) = *s++;
break;
case 'w':
if(s+2 > e) goto Err;
*va_arg(arg, int*) = s[0]<<8 | s[1];
s += 2;
break;
case 'l':
if(s+4 > e) goto Err;
*va_arg(arg, int*) = s[0]<<24 | s[1]<<16 | s[2]<<8 | s[3];
s += 4;
break;
case 'v':
if(s+4 > e) goto Err;
*va_arg(arg, vlong*) =
(vlong)s[0]<<56 |
(vlong)s[1]<<48 |
(vlong)s[2]<<40 |
(vlong)s[3]<<32 |
(vlong)s[4]<<24 |
(vlong)s[5]<<16 |
(vlong)s[6]<<8 |
(vlong)s[7];
s += 8;
break;
}
}
va_end(arg);
return s - b;
Err:
va_end(arg);
return -1;
}

int
pack(uchar *s, int n, char *fmt, ...)
{
va_list arg;
uchar *b, *e;
vlong v;
int i;

b = s;
e = b + n;
va_start(arg, fmt);
for(; *fmt; fmt++) {
switch(*fmt){
case '_':
i = 0;
if(0){
case 'b':
i = va_arg(arg, int);
}
if(s+1 > e) goto Err;
*s++ = i & 0xFF;
break;
case 'w':
i = va_arg(arg, int);
if(s+2 > e) goto Err;
*s++ = (i>>8) & 0xFF;
*s++ = i & 0xFF;
break;
case 'l':
i = va_arg(arg, int);
if(s+4 > e) goto Err;
*s++ = (i>>24) & 0xFF;
*s++ = (i>>16) & 0xFF;
*s++ = (i>>8) & 0xFF;
*s++ = i & 0xFF;
break;
case 'v':
v = va_arg(arg, vlong);
if(s+8 > e) goto Err;
*s++ = (v>>56) & 0xFF;
*s++ = (v>>48) & 0xFF;
*s++ = (v>>40) & 0xFF;
*s++ = (v>>32) & 0xFF;
*s++ = (v>>24) & 0xFF;
*s++ = (v>>16) & 0xFF;
*s++ = (v>>8) & 0xFF;
*s++ = v & 0xFF;
break;
case '*':
i = va_arg(arg, int);
if(s+i > e) goto Err;
memmove(s, va_arg(arg, void*), i);
s += i;
break;
}
}
va_end(arg);
return s - b;
Err:
va_end(arg);
return -1;
}

int
peer(int fd, int incoming, char *addr)
{
uchar buf[64+MAXIO], *map, *told, *p, m;
int mechoking, hechoking;
int mewant, hewant;
int workpiece;
int i, o, l, x, n;

if(debug) fprint(2, "peer %s: %s connected\n", addr, incoming ? "incoming" : "outgoing");

for(i=0; i<2; i++){
if((incoming && i) || (!incoming && !i)){
if(debug) fprint(2, "peer %s: -> handshake\n", addr);
n = pack(buf, sizeof(buf), "*________**",
20, "\x13BitTorrent protocol",
sizeof(infohash), infohash,
sizeof(peerid), peerid);
if(write(fd, buf, n) != n)
return 1;
}
if((incoming && !i) || (!incoming && i)){
n = 20 + 8 + sizeof(infohash);
if((n = readn(fd, buf, n)) != n)
return 1;
if(memcmp(buf, "\x13BitTorrent protocol", 20))
return 0;
if(memcmp(infohash, buf + 20 + 8, sizeof(infohash)))
return 0;
if(debug) fprint(2, "peer %s: <- handshake\n", addr);
}
}
if(readn(fd, buf, sizeof(peerid)) != sizeof(peerid))
return 1;
if(memcmp(peerid, buf, sizeof(peerid)) == 0)
return 0;
if(debug) fprint(2, "peer %s: peerid %.*s\n", addr, sizeof(peerid), (char*)buf);

mechoking = 1;
hechoking = 1;
mewant = 0;
hewant = 0;
workpiece = -1;
map = mallocz(nhavemap, 1);
told = malloc(nhavemap);

if(debug) fprint(2, "peer %s: -> bitfield %d\n", addr, nhavemap);
memmove(told, havemap, nhavemap);
n = pack(buf, sizeof(buf), "lb*", nhavemap+1, 0x05, nhavemap, told);
if(write(fd, buf, n) != n)
goto Out;

for(;;){
for(i=0; i<nhavemap; i++){
if(told[i] != havemap[i]){
for(x = i<<3, m = 0x80; m; m >>= 1, x++){
if((~havemap[i] | told[i] | map[i]) & m)
continue;
told[i] |= m;
if(debug) fprint(2, "peer %s: -> have %d\n", addr, x);
n = pack(buf, sizeof(buf), "lbl", 1+4, 0x04, x);
if(write(fd, buf, n) != n)
goto Out;
}
}
if(!mewant && (map[i] & ~havemap[i])){
mewant = 1;
if(debug) fprint(2, "peer %s: -> interested\n", addr);
n = pack(buf, sizeof(buf), "lb", 1, 0x02);
if(write(fd, buf, n) != n)
goto Out;
}
}
if(!hechoking && mewant){
x = workpiece;
if(x >= 0 && pieces[x].brk < pieces[x].len)
{}
else x = pickpiece(map);
if(x >= 0){
o = pieces[x].brk;
l = pieces[x].len - o;
if(l > MAXIO)
l = MAXIO;
if(debug) fprint(2, "peer %s: -> request %d %d %d\n", addr, x, o, l);
n = pack(buf, sizeof(buf), "lblll", 1+4+4+4, 0x06, x, o, l);
if(write(fd, buf, n) != n)
goto Out;
workpiece = x;
}
}
if(mechoking && hewant){
mechoking = 0;
if(debug) fprint(2, "peer %s: -> unchoke\n", addr);
n = pack(buf, sizeof(buf), "lb", 1, 0x01);
if(write(fd, buf, n) != n)
goto Out;
}

if(readn(fd, buf, 4) != 4)
break;
unpack(buf, 4, "l", &n);
if(n < 0 || n > sizeof(buf))
break;
if(n == 0)
continue;
if(readn(fd, buf, n) != n)
break;

n--;
p = buf+1;
switch(*buf){
case 0x00: // Choke
hechoking = 1;
workpiece = -1;
if(debug) fprint(2, "peer %s: <- choke\n", addr);
break;
case 0x01: // Unchoke
hechoking = 0;
if(debug) fprint(2, "peer %s: <- unchoke\n", addr);
break;
case 0x02: // Interested
hewant = 1;
if(debug) fprint(2, "peer %s: <- interested\n", addr);
break;
case 0x03: // Notinterested
hewant = 0;
if(debug) fprint(2, "peer %s: <- notinterested\n", addr);
break;
case 0x04: // Have <piceindex>
if(unpack(p, n, "l", &x) < 0)
goto Out;
if(debug) fprint(2, "peer %s: <- have %d\n", addr, x);
if(x < 0 || x >= npieces)
continue;
map[x>>3] |= 0x80>>(x&7);
break;
case 0x05: // Bitfield
if(debug) fprint(2, "peer %s: <- bitfield %d\n", addr, n);
if(n != nhavemap)
continue;
memmove(map, p, n);
break;
case 0x06: // Request <index> <begin> <length>
if(unpack(p, n, "lll", &x, &o, &l) < 0)
goto Out;
if(debug) fprint(2, "peer %s: <- request %d %d %d\n", addr, x, o, l);
if(x < 0 || x >= npieces)
continue;
if(!hewant || mechoking || (~havemap[x>>3]&(0x80>>(x&7))))
continue;
if(debug) fprint(2, "peer %s: -> piece %d %d\n", addr, x, o);
n = 4+1+4+4;
if(l > MAXIO)
l = MAXIO;
if((l = rwpiece(0, x, buf + n, l, o)) <= 0)
continue;
n = pack(buf, sizeof(buf), "lbll", 1+4+4+l, 0x07, x, o);
n += l;
if(write(fd, buf, n) != n)
goto Out;
lock(&stats);
stats.up += n;
unlock(&stats);
break;
case 0x07: // Piece <index> <begin> <block>
if(unpack(p, n, "ll", &x, &o) != 8)
goto Out;
p += 8;
n -= 8;
lock(&stats);
stats.down += n;
unlock(&stats);
if(debug) fprint(2, "peer %s: <- piece %d %d %d\n", addr, x, o, n);
if(x < 0 || x >= npieces)
continue;
if((pieces[x].brk != o) || (havemap[x>>3]&(0x80>>(x&7))))
continue;
if(rwpiece(1, x, p, n, o) == n){
if((pieces[x].brk = o+n) == pieces[x].len){
if(!havepiece(x))
pieces[x].brk = 0;
}
}
break;
case 0x08: // Cancel <index> <begin> <length>
if(unpack(p, n, "lll", &x, &o, &l) < 0)
goto Out;
if(debug) fprint(2, "peer %s: <- cancel %d %d %d\n", addr, x, o, l);
break;
case 0x09: // Port <port>
if(unpack(p, n, "l", &x) < 0)
goto Out;
if(debug) fprint(2, "peer %s: <- port %d\n", addr, x);
break;
}
}

Out:
free(told);
free(map);
return 1;
}

void
server(void)
{
char addr[64], adir[40], ldir[40];
int afd, lfd, dfd, pid, nprocs;
NetConnInfo *ni;

afd = -1;
nprocs = 0;
for(port=6881; port<6890; port++){
snprint(addr, sizeof(addr), "tcp!*!%d", port);
if((afd = announce(addr, adir)) >= 0)
break;
}
if(afd < 0){
fprint(2, "announce: %r");
return;
}
if(rfork(RFFDG|RFPROC|RFMEM))
return;
for(;;){
if((lfd = listen(adir, ldir)) < 0){
fprint(2, "listen: %r");
break;
}
while(nprocs >= SRVPROCS)
if(waitpid() > 0)
nprocs--;
nprocs++;
if(pid = rfork(RFFDG|RFPROC|RFMEM)){
if(pid < 0)
nprocs--;
close(lfd);
continue;
}
if((dfd = accept(lfd, ldir)) < 0){
fprint(2, "accept: %r");
break;
}
ni = getnetconninfo(ldir, dfd);
peer(dfd, 1, ni ? ni->raddr : "???");
if(ni) freenetconninfo(ni);
break;
}
exits(0);
}

void
client(char *ip, char *port)
{
static Dict *peerqh, *peerqt;
static QLock peerslk;
static int nprocs;
char *addr;
Dict *d;
int fd;

if(ip == nil || port == nil)
return;

d = mallocz(sizeof(*d) + 64, 1);
snprint(addr = d->str, 64, "tcp!%s!%s", ip, port);
qlock(&peerslk);
if(dlook(peerqh, addr)){
qunlock(&peerslk);
free(d);
return;
}
d->len = strlen(addr);
d->typ = 'd';
d->val = d;
/* enqueue to front */
if((d->next = peerqh) == nil)
peerqt = d;
peerqh = d;
if(nprocs >= CLIPROCS){
qunlock(&peerslk);
return;
}
nprocs++;
qunlock(&peerslk);
if(rfork(RFFDG|RFPROC|RFMEM|RFNOWAIT))
return;

for(;;){
qlock(&peerslk);
/* dequeue and put to tail */
if(d = peerqh){
if((peerqh = d->next) == nil)
peerqt = nil;
d->next = nil;
if(peerqt)
peerqt->next = d;
else
peerqh = d;
peerqt = d;
} else
nprocs--;
qunlock(&peerslk);
if(d == nil)
exits(0);
addr = d->str;
if(debug) fprint(2, "client %s\n", addr);
if((fd = dial(addr, nil, nil, nil)) >= 0){
peer(fd, 0, addr);
close(fd);
}
sleep(1000+nrand(5000));
}
}

int
hopen(char *url, ...)
{
int conn, ctlfd, fd, n;
char buf[1024+1];
va_list arg;

snprint(buf, sizeof buf, "%s/clone", mntweb);
if((ctlfd = open(buf, ORDWR)) < 0)
return -1;
if((n = read(ctlfd, buf, sizeof buf-1)) <= 0){
close(ctlfd);
return -1;
}
buf[n] = 0;
conn = atoi(buf);
va_start(arg, url);
strcpy(buf, "url ");
n = 4+vsnprint(buf+4, sizeof(buf)-4, url, arg);
va_end(arg);
if(write(ctlfd, buf, n) != n){
ErrOut:
close(ctlfd);
return -1;
}
snprint(buf, sizeof buf, "%s/%d/body", mntweb, conn);
if((fd = open(buf, OREAD)) < 0)
goto ErrOut;
close(ctlfd);
return fd;
}

void
webseed(Dict *w, File *f)
{
int fd, err, n, m, o, p, x, y;
uchar buf[MAXIO];
vlong off, len;
Dict *w0;
char *s;

if(w == nil || f == nil || finished())
return;
if(rfork(RFPROC|RFMEM))
return;
w0 = w;
Retry:
if(debug) fprint(2, "webseed %s %s\n", w->str, f->name);
s = strrchr(w->str, '/');
if(s && s[1] == 0)
fd = hopen("%s%s", w->str, f->name);
else
fd = hopen("%s", w->str);
if(fd < 0){
Error:
if(debug) fprint(2, "webseed %s %s: %r\n", w->str, f->name);
if(finished())
exits(0);
if((w = w->next) == w0)
exits(0);
goto Retry;
}

err = 0;
off = f->off;
len = f->len;
while(len > 0 && !finished()){
m = sizeof(buf);
if(len < m)
m = len;
if((n = read(fd, buf, m)) <= 0)
break;

x = off / blocksize;
p = off - (vlong)x*blocksize;
off += n;
len -= n;
y = off / blocksize;

o = 0;
while(n > 0){
m = pieces[x].len - p;
if(m > n)
m = n;
if((havemap[x>>3] & (0x80>>(x&7))) == 0)
rwpiece(1, x, buf+o, m, p);
if(x == y)
break;
o += m;
n -= m;
p = 0;
if(havepiece(x++))
continue;
if(++err > 10){
close(fd);
werrstr("file corrupted");
goto Error;
}
}
}
havepiece(off / blocksize);
havepiece(f->off / blocksize);
close(fd);
exits(0);
}

void
clients4(uchar *p, int len)
{
char ip[16], port[6];

while(len >= 6){
len -= 6;
snprint(ip, sizeof(ip), "%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
snprint(port, sizeof(port), "%d", p[4]<<8 | p[5]);
p += 6;
client(ip, port);
}
}

void
webtracker(char *url)
{
char *event, *p;
Dict *d, *l;
int n, fd;

if(rfork(RFPROC|RFMEM))
return;
if(debug) fprint(2, "webtracker %s\n", url);

event = "&event=started";
for(;;){
vlong up, down, left;

lock(&stats);
up = stats.up;
down = stats.down;
left = stats.left;
unlock(&stats);

d = nil;
if((fd = hopen("%s?info_hash=%.*H&peer_id=%.*H&port=%d&"
"uploaded=%lld&downloaded=%lld&left=%lld&compact=1&no_peer_id=1%s",
url, sizeof(infohash), infohash, sizeof(peerid), peerid, port,
up, down, left, event)) >= 0){
event = "";
n = readall(fd, &p);
close(fd);
bparse(p, p+n, &d);
free(p);
} else if(debug) fprint(2, "tracker %s: %r\n", url);
if(l = dlook(d, "peers")){
if(l->typ == 's')
clients4((uchar*)l->str, l->len);
else for(; l && l->typ == 'l'; l = l->next)
client(dstr(dlook(l->val, "ip")), dstr(dlook(l->val, "port")));
}
n = 0;
if(p = dstr(dlook(d, "interval")))
n = atoi(p);
if(n < 10 | n > 60*60)
n = 2*60;
freedict(d);
sleep(n * 1000 + nrand(5000));
}
}

int
udpaddr(char addr[64], int naddr, char *url)
{
int port;
char *x;

if((url = strchr(url, ':')) == nil)
return -1;
url++;
while(*url == '/')
url++;
if(x = strchr(url, ':')){
port = atoi(x+1);
} else {
port = 80;
if((x = strchr(url, '/')) == nil)
x = strchr(url, 0);
}
snprint(addr, naddr, "udp!%.*s!%d", (int)(x-url), url, port);
return 0;
}

void
udptracker(char *url)
{
int fd, event, n, m, a, i;
int transid, interval;
vlong connid;
uchar buf[MAXIO];
char addr[64];

if(udpaddr(addr, sizeof(addr), url) < 0)
return;
if(rfork(RFPROC|RFMEM))
return;
if(debug) fprint(2, "udptracker %s\n", addr);

event = 1;
for(;;){
alarm(30000);
if((fd = dial(addr, 0, 0, 0)) < 0)
goto Sleep;

/* connect */
transid = rand();
n = pack(buf, sizeof(buf), "vll", 0x41727101980LL, 0, transid);
if(write(fd, buf, n) != n)
goto Sleep;
for(;;){
if((n = read(fd, buf, sizeof(buf))) <= 0)
goto Sleep;
if(unpack(buf, n, "llv", &a, &i, &connid) < 0)
continue;
if(a == 0 && i == transid)
break;
}
alarm(0);

/* announce */
transid = rand();
lock(&stats);
n = pack(buf, sizeof(buf), "vll**vvvl____llw",
connid, 1, transid,
sizeof(infohash), infohash,
sizeof(peerid), peerid,
stats.down,
stats.left,
stats.up,
event,
0, -1,
port);
unlock(&stats);

interval = 0;
alarm(30000);
if(write(fd, buf, n) != n)
goto Sleep;
for(;;){
if((n = read(fd, buf, sizeof(buf))) <= 0)
goto Sleep;
if((m = unpack(buf, n, "lll________", &a, &i, &interval)) < 0)
continue;
if(a == 1 && i == transid){
clients4(buf+m, n - m);
break;
}
}
event = 0;
Sleep:
alarm(0);
if(fd >= 0)
close(fd);
if(interval < 10 | interval > 60*60)
interval = 2*60;
sleep(interval * 1000 + nrand(5000));
}
}

void
tracker(char *url)
{
static Dict *trackers;
static QLock trackerslk;
Dict *d;
int n;

if(url == nil)
return;
qlock(&trackerslk);
if(dlook(trackers, url)){
qunlock(&trackerslk);
return;
}
n = strlen(url);
d = mallocz(sizeof(*d) + n+1, 1);
strcpy(d->str, url);
d->len = n;
d->typ = 'd';
d->val = d;
d->next = trackers;
trackers = d;
url = d->str;
qunlock(&trackerslk);
if(!cistrncmp(url, "udp:", 4))
udptracker(url);
else
webtracker(url);
}

int
Hfmt(Fmt *f)
{
uchar *s, *e;
s = va_arg(f->args, uchar*);
if(f->flags & FmtPrec)
e = s + f->prec;
else
e = s + strlen((char*)s);
for(; s < e; s++)
if(fmtprint(f, *s && ((*s >= '0' && *s <= '9') ||
(*s >= 'a' && *s <= 'z') ||
(*s >= 'A' && *s <= 'Z') ||
strchr(".-_~", *s)) ? "%c" : "%%%.2x", *s) < 0)
return -1;
return 0;
}

int
mktorrent(int fd, Dict *alist, Dict *wlist)
{
uchar *b, h[20];
Dir *d;
int n;

if((d = dirfstat(fd)) == nil)
return -1;
if(d->qid.type & QTDIR){
free(d);
werrstr("file is a directory");
return -1;
}
if(d->length == 0){
free(d);
werrstr("empty file");
return -1;
}
npieces = 1;
for(blocksize = 256*1024;;blocksize<<=1){
npieces = (d->length + blocksize-1) / blocksize;
if(npieces <= 8*1024 || blocksize >= 2*1024*1024)
break;
}

/*
* keys in dictionaries have to be ordered alphabetically
*/
print("d8:announce%ld:%s", strlen(alist->str), alist->str);
if(alist->next){
print("13:announce-listl");
print("l%ld:%se", strlen(alist->str), alist->str);
for(alist = alist->next; alist; alist = alist->next)
print("l%ld:%se", strlen(alist->str), alist->str);
print("e");
}

print("4:infod");
print("6:lengthi%llde", d->length);
print("4:name%ld:%s", strlen(d->name), d->name);
print("12:piece lengthi%de", blocksize);
print("6:pieces%d:", npieces*sizeof(h));
free(d);
b = malloc(blocksize);
while((n = readn(fd, b, blocksize)) > 0){
sha1(b, n, h, nil);
if(write(1, h, sizeof(h)) != sizeof(h)){
free(b);
return -1;
}
npieces--;
}
if(npieces){
werrstr("read failed: %r");
return -1;
}
free(b);
print("e");

if(wlist){
if(wlist->next){
print("8:url-listl");
for(; wlist; wlist = wlist->next)
print("%ld:%s", strlen(wlist->str), wlist->str);
print("e");
} else
print("8:url-list%ld:%s", strlen(wlist->str), wlist->str);
}
print("e");

return 0;
}

int
mkdirs(char *s)
{
char *p;
int f;

if(access(s, AEXIST) == 0)
return 0;
for(p=strchr(s+1, '/'); p; p=strchr(p+1, '/')){
*p = 0;
if(access(s, AEXIST)){
if((f = create(s, OREAD, DMDIR | 0777)) < 0){
*p = '/';
return -1;
}
close(f);
}
*p = '/';
}
return 0;
}

char*
fixnamedup(char *s)
{
int n, l;
char *d;
Rune r;

n = 0;
d = strdup(s);
l = strlen(d);
while(*s){
s += chartorune(&r, s);
if(r == ' ')
r = 0xa0;
if((n + runelen(r)) >= l){
l += 64;
d = realloc(d, l);
}
n += runetochar(d + n, &r);
}
d[n] = 0;
return cleanname(d);
}

int
catch(void *, char *msg)
{
if(strstr(msg, "alarm"))
return 1;
postnote(PNGROUP, killgroup, "kill");
return 0;
}

void
usage(void)
{
fprint(2, "usage: %s [ -vsdpc ] [ -m mtpt ] [ -t tracker-url ] "
"[ -w webseed-url ] [ file ]\n", argv0);
exits("usage");
}

Dict*
scons(char *s, Dict *t)
{
Dict *l;

if(s == nil)
return t;
for(l = t; l; l = l->next)
if(strcmp(l->str, s) == 0)
return t;
l = mallocz(sizeof(*l) + strlen(s)+1, 1);
l->next = t;
strcpy(l->str, s);
return l;
}

void
main(int argc, char *argv[])
{
int sflag, pflag, vflag, cflag, fd, i, n;
Dict *alist, *wlist, *info, *torrent, *d, *l;
char *p, *s, *e;
File **fp, *f;
vlong len;

fmtinstall('H', Hfmt);
alist = wlist = nil;
sflag = pflag = vflag = cflag = 0;
ARGBEGIN {
case 'm':
mntweb = EARGF(usage());
break;
case 't':
alist = scons(EARGF(usage()), alist);
break;
case 'w':
wlist = scons(EARGF(usage()), wlist);
break;
case 's':
sflag = 1;
break;
case 'p':
pflag = 1;
break;
case 'v':
vflag = 1;
break;
case 'c':
cflag = 1;
break;
case 'd':
debug++;
break;
default:
usage();
} ARGEND;

fd = 0;
if(*argv)
if((fd = open(*argv, OREAD)) < 0)
sysfatal("open: %r");
if(cflag){
if(alist == nil)
alist = scons(deftrack, alist);
if(mktorrent(fd, alist, wlist) < 0)
sysfatal("%r");
exits(0);
}
if((n = readall(fd, &p)) <= 0)
sysfatal("read torrent: %r");
bparse(p, p+n, &torrent);

alist = scons(dstr(dlook(torrent, "announce")), alist);
for(d = dlook(torrent, "announce-list"); d && d->typ == 'l'; d = d->next)
for(l = d->val; l && l->typ == 'l'; l = l->next)
alist = scons(dstr(l->val), alist);

if(d = dlook(torrent, "url-list")){
if(d->typ == 's')
wlist = scons(dstr(d->val), wlist);
else for(l = d; l && l->typ == 'l'; l = l->next)
wlist = scons(dstr(l->val), wlist);
/* make wlist into a ring */
for(l = wlist; l && l->next; l = l->next)
;
if(l) l->next = wlist;
}

if(alist == nil && wlist == nil)
sysfatal("no trackers or webseeds in torrent");

if((d = info = dlook(torrent, "info")) == nil)
sysfatal("no meta info in torrent");
for(s = e = d->start; d && d->typ == 'd'; d = d->next)
e = d->end;
sha1((uchar*)s, e - s, (uchar*)infohash, nil);
free(p);

fp = &files;
if(d = dlook(info, "files")){
for(; d && d->typ == 'l'; d = d->next){
Dict *di;

if((s = dstr(dlook(d->val, "length"))) == nil)
continue;
f = mallocz(sizeof(*f), 1);
f->len = atoll(s);
f->name = dstr(dlook(info, "name"));
for(di = dlook(d->val, "path"); di && di->typ == 'l'; di = di->next)
if(s = dstr(di->val))
f->name = f->name ? smprint("%s/%s", f->name, s) : s;
*fp = f;
fp = &f->next;
}
} else if(s = dstr(dlook(info, "length"))){
f = mallocz(sizeof(*f), 1);
f->len = atoll(s);
f->name = dstr(dlook(info, "name"));
*fp = f;
}
len = 0;
for(f = files; f; f = f->next){
if(f->name == nil || f->len <= 0)
sysfatal("bogus file entry in meta info");
s = fixnamedup(f->name);
if(vflag) fprint(pflag ? 2 : 1, "%s\n", s);
if((f->fd = open(s, ORDWR)) < 0){
if(mkdirs(s) < 0)
sysfatal("mkdirs: %r");
if((f->fd = create(s, ORDWR, 0666)) < 0)
sysfatal("create: %r");
}
f->off = len;
len += f->len;
}
if(len <= 0)
sysfatal("no files in torrent");

if((s = dstr(dlook(info, "piece length"))) == nil)
sysfatal("missing piece length in meta info");
if((blocksize = atoi(s)) <= 0)
sysfatal("bogus piece length in meta info");
d = dlook(info, "pieces");
if(d == nil || d->typ != 's' || d->len <= 0 || d->len % 20)
sysfatal("bad or no pices in meta info");
npieces = d->len / 20;
pieces = mallocz(sizeof(Piece) * npieces, 1);
nhavemap = (npieces+7) / 8;
havemap = mallocz(nhavemap, 1);
for(i = 0; i<npieces; i++){
pieces[i].hash = (uchar*)d->str + i*20;
if(len < blocksize)
pieces[i].len = len;
else
pieces[i].len = blocksize;
len -= pieces[i].len;
stats.left += pieces[i].len;
}
if(len)
sysfatal("pieces do not match file length");

for(i = 0; i<npieces; i++)
havepiece(i);

srand(time(0));
atnotify(catch, 1);
switch(i = rfork(RFPROC|RFMEM|RFNOTEG)){
case -1:
sysfatal("fork: %r");
case 0:
memmove(peerid, "-NF9001-", 8);
for(i=8; i<sizeof(peerid); i++)
peerid[i] = nrand(10)+'0';
server();
for(; alist; alist = alist->next)
tracker(alist->str);
for(f = files, l = wlist; f && l; f = f->next, l = l->next)
webseed(l, f);
while(waitpid() != -1)
;
break;
default:
killgroup = i;
do {
sleep(1000);
if(pflag)
print("%d %d\n", nhavepieces, npieces);
} while(!finished() || sflag);
}
postnote(PNGROUP, killgroup, "kill");
exits(0);
}

</pre>
</td></tr></table>
</td></tr></table>





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