Problems of AF_INET domain socket regarding out-of-band data.

[Takashi Yano]

Hello,

I have found a few problems of AF_INET domain socket regarding
out-of-band data.

1. recv() with MSG_OOB flag eats normal data if no OOB data
  is sent yet.

2. Calling recv() with MSG_OOB flag is blocked if no OOB data
  is sent yet.

3. Calling recv() without MSG_OOB flag after receiving OOB data
  is blocked even if received data exist in buffer. 

Regarding problem 1 and 2, POSIX states as follows about recv().
[EINVAL]
The MSG_OOB flag is set and no out-of-band data is available.
http://pubs.opengroup.org/onlinepubs/9699919799/functions/recv.html

Attached is a sample program to reproduce these problems.
Argument to this program specifies the test mode.
0: cause problem 1
2: cause problem 2
3: cause problem 3

Expected results:
debian:~/OOB> ./server_client 0
recv(OOB): Invalid argument
OOB   :  (-1)
NORMAL: 1234567890 (10)
debian:~/OOB> ./server_client 1
OOB   : A (1)
NORMAL: 1234567890 (10)
debian:~/OOB> ./server_client 2
recv(OOB): Invalid argument
OOB   :  (-1)
NORMAL: 1234567890 (10)
debian:~/OOB> ./server_client 3
OOB   : A (1)
NORMAL: 1234567890 (10)
debian:~/OOB>

Result on cygwin:
[yano@Express5800-S70 ~/OOB]$ ./server_client 0
OOB   : 1234567890 (10)
NORMAL:  (0)
[yano@Express5800-S70 ~/OOB]$ ./server_client 1
OOB   : A (1)
NORMAL: 1234567890 (10)
[yano@Express5800-S70 ~/OOB]$ ./server_client 2
[yano@Express5800-S70 ~/OOB]$ ./server_client 3
OOB   : A (1)
[yano@Express5800-S70 ~/OOB]$

Only the result of test mode 1 is as expected.

I have confirmed this occurs in both latest 32bit and 64 bit
cygwin.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>
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