Okay, here's my test program. Compile and run with no arguments, then
connect to it from another machine - on a linux box I just did:
python
import socket
s = socket.socket()
s.connect(("name-of-windows-box", 12345))
At this point, nbcheck printed:
listening to port 12345 on host xp1 (10.1.2.40)
got connection from 10.1.2.14
trying to write 100000000
100000000 bytes written
When I hit return to exit from nbcheck, it does not actually exit until
the remote socket is closed.
The VM usage is 100M, which is all the data array that I allocated, so
it doesn't look like the write() call allocated anything in my process
space.
This behavior makes some sense to me, but it's not how I expect it to
work (based on the write(2) man page and how it works on linux). It's
more like asynchronous write than non-blocking write. Using O_NONBLOCK
instead of O_NDELAY doesn't change the behavior.
Thanks,
Wayne
#include <stdio.h>
#include <ctype.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <assert.h>
main()
{
int i, fd, fd2, len;
struct hostent *hp;
struct protoent *pp;
char hostname[64];
struct sockaddr_in lAddr, rAddr;
char* data;
int datalen, datapos;
gethostname(hostname, 64);
pp = getprotobyname("tcp");
hp = gethostbyname(hostname);
assert(pp && hp);
fd = socket(AF_INET, SOCK_STREAM, pp->p_proto);
assert(fd >= 0);
lAddr.sin_family = hp->h_addrtype;
memcpy((char *)&lAddr.sin_addr.s_addr, (char *)hp->h_addr,
sizeof(lAddr.sin_addr.s_addr));
lAddr.sin_port = htons(12345);
i = bind(fd, (struct sockaddr *)&lAddr, sizeof(lAddr));
assert(i >= 0);
printf("listening to port %d host %s (%s)\n", ntohs(lAddr.sin_port),
hostname, inet_ntoa(lAddr.sin_addr));
i = listen(fd, 5);
assert(i >= 0);
len = sizeof(rAddr);
memset(&rAddr, 0, sizeof(rAddr));
fd2 = accept(fd, (struct sockaddr *)&rAddr, &len);
assert(fd2 >= 0);
printf("got connection from %s\n", inet_ntoa(rAddr.sin_addr));
i = fcntl(fd2, F_SETFL, O_NDELAY);
assert(i >= 0);
datalen = (int) 1e8;
data = (char *) malloc(datalen);
datapos = 0;
while (datapos < datalen) {
fd_set wfds;
FD_ZERO(&wfds);
FD_SET(fd2, &wfds);
i = select(fd2 + 1, NULL, &wfds, NULL, NULL);
assert(i == 1);
printf("trying to write %d bytes\n", datalen - datapos);
i = write(fd2, data + datapos, datalen - datapos);
printf("%d bytes written\n", i);
assert(i > 0);
datapos += i;
assert(datapos <= datalen);
}
printf("hit return to exit ");
getchar();
exit(0);
}
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