Attachment 3518 Details for Bug 3304 – debug select failures

[patch] debug select failures

debug-select.diff (text/plain), 2.96 KB, created by Damien Miller on 2021-05-13 07:45:54 AEST

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Creator: Damien Miller

Created: 2021-05-13 07:45:54 AEST

Size: 2.96 KB

patch

obsolete

>diff --git a/channels.c b/channels.c
>index 32d1f6178..6834bc56d 100644
>--- a/channels.c
>+++ b/channels.c
>@@ -2438,6 +2438,7 @@ channel_prepare_select(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp,
> {
> 	u_int n, sz, nfdset;
> 
>+	debug_f("entering, maxfd = %d", *maxfdp);
> 	channel_before_prepare_select(ssh); /* might update channel_max_fd */
> 
> 	n = MAXIMUM(*maxfdp, ssh->chanctxt->channel_max_fd);
>@@ -2458,9 +2459,11 @@ channel_prepare_select(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp,
> 	memset(*readsetp, 0, sz);
> 	memset(*writesetp, 0, sz);
> 
>+	debug_f("before handler, maxfd = %d", *maxfdp);
> 	if (!ssh_packet_is_rekeying(ssh))
> 		channel_handler(ssh, CHAN_PRE, *readsetp, *writesetp,
> 		    minwait_secs);
>+	debug_f("done, maxfd = %d", *maxfdp);
> }
> 
> /*
>diff --git a/clientloop.c b/clientloop.c
>index 219f0e904..2a52425ed 100644
>--- a/clientloop.c
>+++ b/clientloop.c
>@@ -85,6 +85,7 @@
> #include <pwd.h>
> #include <unistd.h>
> #include <limits.h>
>+#include <fcntl.h>
> 
> #include "openbsd-compat/sys-queue.h"
> #include "xmalloc.h"
>@@ -492,6 +493,25 @@ server_alive_check(struct ssh *ssh)
> 	schedule_server_alive_check();
> }
> 
>+static void
>+debug_bad_fdset(const char *what, fd_set *set, int maxfd)
>+{
>+	int i;
>+
>+	for (i = 0; i < maxfd; i++) {
>+		if (!FD_ISSET(i, set) || fcntl(i, F_GETFL) != -1)
>+			continue;
>+		debug_f("select: %s bad fd %i", what, i);
>+	}
>+}
>+
>+static void
>+debug_bad_select(fd_set *readset, fd_set *writeset, int maxfd)
>+{
>+	debug_bad_fdset("readset", readset, maxfd);
>+	debug_bad_fdset("writeset", writeset, maxfd);
>+}
>+
> /*
>  * Waits until the client can do something (some data becomes available on
>  * one of the file descriptors).
>@@ -504,7 +524,7 @@ client_wait_until_can_do_something(struct ssh *ssh,
> 	struct timeval tv, *tvp;
> 	int timeout_secs;
> 	time_t minwait_secs = 0, now = monotime();
>-	int r, ret;
>+	int oerrno, r, ret;
> 
> 	/* Add any selections by the channel mechanism. */
> 	channel_prepare_select(ssh, readsetp, writesetp, maxfdp,
>@@ -553,9 +573,14 @@ client_wait_until_can_do_something(struct ssh *ssh,
> 		tv.tv_usec = 0;
> 		tvp = &tv;
> 	}
>-
> 	ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
> 	if (ret == -1) {
>+		if (errno != EINTR) {
>+			oerrno = errno;
>+			debug_f("select: %s", strerror(errno));
>+			debug_bad_select(*readsetp, *writesetp, *maxfdp);
>+			errno = oerrno;
>+		}
> 		/*
> 		 * We have to clear the select masks, because we return.
> 		 * We have to return, because the mainloop checks for the flags
>@@ -571,13 +596,14 @@ client_wait_until_can_do_something(struct ssh *ssh,
> 			fatal_fr(r, "sshbuf_putf");
> 		quit_pending = 1;
> 	} else if (options.server_alive_interval > 0 && !FD_ISSET(connection_in,
>-	    *readsetp) && monotime() >= server_alive_time)
>+	    *readsetp) && monotime() >= server_alive_time) {
> 		/*
> 		 * ServerAlive check is needed. We can't rely on the select
> 		 * timing out since traffic on the client side such as port
> 		 * forwards can keep waking it up.
> 		 */
> 		server_alive_check(ssh);
>+	}
> }
> 
> static void

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