Paul L. Allen wrote:
Dr. Stephen Henson wrote:
On Wed, Feb 18, 2004, Paul L. Allen wrote:
[ ... problem statement omitted ...]
Firstly I hope you are checking the return values from BIO_gets(),
BIO_puts()
and BIO_flush().
Yes, I am. All are OK up to the hang.
Presumably you are using a buffering BIO to get the BIO_gets()
functionality.
It is possible something odd is happening in there. Are the lines you are
using very long?
If I'm understanding it right, there's a socket BIO associated with the
underlying socket. An SSL structure is associated with the input and
output
of the socket BIO. An SSL BIO is connected to the SSL struct, and finally
a buffered BIO is pushed on in front of the SSL BIO. The server has a
setup that matches, and the whole contraption generally works fine.
Some lines are long. In one case, the client sends a request of 4534
bytes.
The server responds with a query to the client of 32 bytes. The client
sends back a response of 35 bytes. The server then sends back a response
to the original request of 92 bytes. The client then sends a new message
of four bytes and hangs in BIO_flush(). I've been sending long messages
like this since about this time last year, but it's possible that I've
crept
up a bit in size over time. Is there a boundary at 4096, or something?
It might be an idea to place some debugging printfs around the low level
socket calls in crypto/bio/bss_sock.c to see if the hang is occurring
at that
level.
I can do that. Thanks!
OK, I've instrumented crypto/bio/bss_sock.c with fprintf/fflush pairs
on entry and exit from the socket calls. BIO_puts() ends up using
sock_write() and the call to sock_write() is usually triggered by a
call to BIO_flush(). When it hangs, it stops somewhere in BIO_flush()
prior to the call to sock_write(). After a timeout of 60 seconds or
so, sock_write() gets called and returns, and then the process dies with
an Alarm Clock error. If I catch SIGALRM with a null handler, the process
hangs forever without calling sock_write(). While the process is hung,
it consumes all available cpu and issues no system calls. Increasing
the read and write buffer sizes (to 8192 from the default 1024) of the
buffered BIO's on each end has no effect.
I guess I'll start instrumenting the code that implements the buffered
and SSL BIO's next. Anybody have any other suggestions?
Paul Allen
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