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bug#40665: 28.0.50; tls hang on local ssl
From: |
Derek Zhou |
Subject: |
bug#40665: 28.0.50; tls hang on local ssl |
Date: |
Tue, 21 Apr 2020 22:20:03 +0000 (UTC) |
User-agent: |
mu4e 1.2.0; emacs 27.0.91 |
Derek Zhou writes:
> Robert Pluim writes:
>
>> Thatʼs always possible. You'd have to stick some instrumentation in
>> things like connect_network_socket and wait_reading_process_output to
>> narrow it down.
>>
> I think what happened is gnutls's internal buffering exhausts the
> available data from the socket, so select blocks. There is an comment in
> the code said gnutls leave one byte in the socket for select, but I
> don't think it is doing this anymore. The following patch move the check
> before the select and skip the select if there is data to be read in
> gnutls. It fixed the occational stall in https.
Sorry, the previous patch was wrong. Cannot reuse the fd_set intended
for select. Corrected:
diff --git a/src/process.c b/src/process.c
index 91d426103d..49b034b1a7 100644
--- a/src/process.c
+++ b/src/process.c
@@ -5566,7 +5566,38 @@ wait_reading_process_output (intmax_t time_limit, int
nsecs, int read_kbd,
}
#endif
-/* Non-macOS HAVE_GLIB builds call thread_select in xgselect.c. */
+#ifdef HAVE_GNUTLS
+ /* GnuTLS buffers data internally. We need to check if some
+ data is available in the buffers manually before the select.
+ And if so, we need to skip the select which could block */
+ {
+ fd_set tls_available;
+ FD_ZERO (&tls_available);
+ nfds = 0;
+ for (channel = 0; channel < FD_SETSIZE; ++channel)
+ if (! NILP (chan_process[channel]))
+ {
+ struct Lisp_Process *p =
+ XPROCESS (chan_process[channel]);
+ if (p && p->gnutls_p && p->gnutls_state
+ && ((emacs_gnutls_record_check_pending
+ (p->gnutls_state))
+ > 0))
+ {
+ nfds++;
+ eassert (p->infd == channel);
+ FD_SET (p->infd, &tls_available);
+ }
+ }
+ /* don't select if we have something here */
+ if (nfds > 0) {
+ Available = tls_available;
+ goto SELECT_END;
+ }
+ }
+#endif
+
+ /* Non-macOS HAVE_GLIB builds call thread_select in xgselect.c. */
#if defined HAVE_GLIB && !defined HAVE_NS
nfds = xg_select (max_desc + 1,
&Available, (check_write ? &Writeok : 0),
@@ -5582,65 +5613,9 @@ wait_reading_process_output (intmax_t time_limit, int
nsecs, int read_kbd,
(check_write ? &Writeok : 0),
NULL, &timeout, NULL);
#endif /* !HAVE_GLIB */
-
-#ifdef HAVE_GNUTLS
- /* GnuTLS buffers data internally. In lowat mode it leaves
- some data in the TCP buffers so that select works, but
- with custom pull/push functions we need to check if some
- data is available in the buffers manually. */
- if (nfds == 0)
- {
- fd_set tls_available;
- int set = 0;
-
- FD_ZERO (&tls_available);
- if (! wait_proc)
- {
- /* We're not waiting on a specific process, so loop
- through all the channels and check for data.
- This is a workaround needed for some versions of
- the gnutls library -- 2.12.14 has been confirmed
- to need it. */
- for (channel = 0; channel < FD_SETSIZE; ++channel)
- if (! NILP (chan_process[channel]))
- {
- struct Lisp_Process *p =
- XPROCESS (chan_process[channel]);
- if (p && p->gnutls_p && p->gnutls_state
- && ((emacs_gnutls_record_check_pending
- (p->gnutls_state))
- > 0))
- {
- nfds++;
- eassert (p->infd == channel);
- FD_SET (p->infd, &tls_available);
- set++;
- }
- }
- }
- else
- {
- /* Check this specific channel. */
- if (wait_proc->gnutls_p /* Check for valid process. */
- && wait_proc->gnutls_state
- /* Do we have pending data? */
- && ((emacs_gnutls_record_check_pending
- (wait_proc->gnutls_state))
- > 0))
- {
- nfds = 1;
- eassert (0 <= wait_proc->infd);
- /* Set to Available. */
- FD_SET (wait_proc->infd, &tls_available);
- set++;
- }
- }
- if (set)
- Available = tls_available;
- }
-#endif
}
+ SELECT_END:
xerrno = errno;
/* Make C-g and alarm signals set flags again. */
- bug#40665: 28.0.50; tls hang on local ssl, (continued)
- bug#40665: 28.0.50; tls hang on local ssl, Robert Pluim, 2020/04/19
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/20
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/20
- bug#40665: 28.0.50; tls hang on local ssl, Robert Pluim, 2020/04/21
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/21
- bug#40665: 28.0.50; tls hang on local ssl, Robert Pluim, 2020/04/21
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/21
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/21
- bug#40665: 28.0.50; tls hang on local ssl, Robert Pluim, 2020/04/21
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/21
- bug#40665: 28.0.50; tls hang on local ssl,
Derek Zhou <=
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/21
- bug#40665: 28.0.50; tls hang on local ssl, Robert Pluim, 2020/04/22
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/22
- bug#40665: 28.0.50; tls hang on local ssl, Robert Pluim, 2020/04/22
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/22
- bug#40665: 28.0.50; tls hang on local ssl, Robert Pluim, 2020/04/22
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/22
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/22
- bug#40665: 28.0.50; tls hang on local ssl, Derek Zhou, 2020/04/24
- bug#40665: 28.0.50; tls hang on local ssl, Robert Pluim, 2020/04/24