Date: Mon, 21 May 2007 00:11:48 +0200 From: Martin Kulas <coolaz@web.de> To: freebsd-current@freebsd.org Subject: [SCTP] nonblocking write() Message-ID: <20070520221148.GA2169@thunderbird.local>
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Hello!
I hope this is the right mailing list. I am running -CURRENT and=20
I am trying to get an application (thttpd) to use SCTP sockets =20
in one-to-one style.
But it does not work. I tracked the problem down to this:
The SCTP socket is made non-blocking. Then write() is called.
Write() succeeds if we do not write too many bytes;
net.inet.sctp.sendspace is the limit for an successfull write().
Is this behaviour intended?
Perhaps I am coding something wrong, so here is sample code:
$ nl nb.c
1 #include <stdio.h>
2 #include <arpa/inet.h>
3 #include <netinet/in.h>
4 #include <sys/types.h>
5 #include <unistd.h>
6 #include <sys/socket.h>
7 #include <err.h>
8 #include <strings.h>
9 #include <errno.h>
10 #include <string.h>
11 #include <fcntl.h>
=09
12 #define DST_IP "127.0.0.1"
13 #define DST_PORT 1234
=09
14 int
15 main()
16 {
17 int s;
18 struct sockaddr_in sa;
19 int ret;
20 int n;
21 char buf[BUFSZ];
22 int toSend;
=09
23 printf("BUFSZ: %u\n", BUFSZ);
24 #ifdef USE_SCTP
25 printf("using sctp\n");
26 s =3D socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP);
27 #else
28 printf("using tcp\n");
29 s =3D socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
30 #endif
31 if ( s =3D=3D -1 )
32 err(1, "socket() failed");
=09
33 #ifdef USE_NONBLOCKING
34 printf("using nonblocking i/o\n");
35 ret =3D fcntl(s, F_GETFL);
36 if ( ret =3D=3D -1 )
37 err(1, "fcntl() failed\n");
38 ret |=3D O_NONBLOCK;
39 ret =3D fcntl(s, F_SETFL, ret);
40 if ( ret =3D=3D -1 )
41 err(1, "fcntl() failed\n");
42 #endif
=09
43 bzero(&sa, sizeof(sa));
44 sa.sin_family =3D AF_INET;
45 sa.sin_port =3D htons(DST_PORT);
46 n =3D inet_pton(AF_INET, DST_IP, &sa.sin_addr);
47 if ( n !=3D 1 )
48 err(1, "inet_pton() failed");
=09
49 ret =3D connect(s, (struct sockaddr *) &sa, sizeof(sa));
50 if ( ret =3D=3D -1 )
51 err(1, "connect() failed");
52 memset(buf, 'a', BUFSZ);
=09
53 #ifdef USE_WRITE
54 printf("using write() i/o\n");
55 toSend =3D BUFSZ;
56 while ( toSend > 0 ) {
57 n =3D write(s, buf, toSend);
58 if ( n > 0 ) {
59 /* OK */
60 printf("%d bytes send\n", n);
61 toSend -=3D n;
62 } else if ( n =3D=3D 0 ) {
63 err(1, "write() EOF (0 bytes written)\n");
64 } else {
65 printf("n: %d: %s\n", n, strerror(errno));
66 sleep(1);
67 }
68 }
69 #endif
=09
70 return 0;
71 }
$ cc -Wall -DUSE_SCTP -DUSE_WRITE -DUSE_NONBLOCKING -DBUFSZ=3D30000 -o nb n=
b.c=20
$ ./nb =
=20
BUFSZ: 30000
using sctp
using nonblocking i/o
using write() i/o
30000 bytes send
$ cc -Wall -DUSE_SCTP -DUSE_WRITE -DUSE_NONBLOCKING -DBUFSZ=3D300000 -o nb =
nb.c
$ ./nb =
=20
BUFSZ: 300000
using sctp
using nonblocking i/o
using write() i/o
n: -1: Resource temporarily unavailable
n: -1: Resource temporarily unavailable
n: -1: Resource temporarily unavailable
n: -1: Resource temporarily unavailable
n: -1: Resource temporarily unavailable
n: -1: Resource temporarily unavailable
^C
I googled a bit but I do not get any answer if this behaviour is correct=20
for non-blocking SCTP socket in one-to-one style.
Thanks in advance,
Martin
--=20
PGP Key: http://www.stud.uni-hamburg.de/~kulas/mkulas_pubkey.asc
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