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#include <u.h>
#include <libc.h>
enum {
Soh= 0x1,
Eot= 0x4,
Ack= 0x6,
Nak= 0x15,
Cancel= 0x18,
};
int notifyf(void*, char*);
int readupto(uchar*, int);
int receive(int, uchar);
void send(int);
int debug, dfd;
void
main(int argc, char **argv)
{
int fd;
uchar seqno;
ulong bytes;
ARGBEGIN {
case 'd':
dfd = 2;
debug = 1;
break;
} ARGEND
if(argc != 1){
fprint(2, "usage: xmr filename\n");
exits("usage");
}
fd = open("/dev/consctl", OWRITE);
if(fd >= 0)
write(fd, "rawon", 5);
fd = create(argv[0], ORDWR, 0666);
if(fd < 0){
perror("xmr: create");
exits("create");
}
atnotify(notifyf, 1);
send(Nak);
/*
* keep receiving till the other side gives up
*/
bytes = 0;
for(seqno = 1; ; seqno++){
if(receive(fd, seqno) == -1)
break;
bytes += 128;
}
fprint(2, "xmr: received %ld bytes\n", bytes);
exits(0);
}
void
send(int byte)
{
uchar c;
c = byte;
if(write(1, &c, 1) != 1){
fprint(2, "xmr: hungup\n");
exits("hangup");
}
}
int
readupto(uchar *a, int len)
{
int n;
int sofar;
for(sofar = 0; sofar < len; sofar += n){
n = read(0, a, len-sofar);
if(n <= 0){
send(Nak);
return sofar;
}
if(*a == Eot || *a == Cancel)
return sofar + n;
a += n;
}
return sofar;
}
int
receive(int fd, uchar seqno)
{
uchar buf[128+4];
uchar sum;
uchar *p;
int n;
int tries;
int have;
for(have = 0, tries = 0;; tries++){
if(debug)
fprint(dfd, "have == %d\n", have);
if(tries > 10){
fprint(2, "xmr: timed out\n");
if(debug)
close(dfd);
exits("timeout");
}
/* try to gather up a block */
alarm(15*1000);
n = readupto(&buf[have], 132-have);
alarm(0);
have += n;
if(have){
switch(buf[0]){
case Eot:
send(Ack);
return -1;
case Cancel:
fprint(2, "xmr: transfer aborted by sender\n");
exits("cancel");
}
}
if(have != 132)
continue;
/* checksum */
for(p = buf, sum = 0; p < &buf[128+3]; p++)
sum += *p;
/* If invalid block, resynchronize */
if(buf[0] != Soh || buf[2] != (255-buf[1]) || sum != buf[131]){
if(debug){
fprint(dfd, "resync %2.2ux %d %d %ux %ux\n", buf[0],
buf[1], buf[2], sum, buf[131]);
write(dfd, (char*)buf+3, 128);
fprint(dfd, "\n");
}
p = memchr(buf+1, Soh, 131);
if(p){
have = 132-(p-buf);
memmove(buf, p, have);
} else
have = 0;
continue;
}
/* it's probably a real block, so dump it if there's an error */
have = 0;
/* if this is the last block, ack */
if(buf[1] == seqno-1){
tries = 0;
send(Ack);
}else if(buf[1] == seqno){
if(debug)
fprint(dfd, "Ack\n");
send(Ack);
if(write(fd, buf+3, 128) != 128){
fprint(2, "xmr: abort, error writing file\n");
exits("write");
}
return 0;
} else {
send(Nak);
}
}
}
int
notifyf(void *a, char *msg)
{
USED(a);
if(strcmp(msg, "alarm") == 0)
return 1;
return 0;
}
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