Date: Thu, 4 Oct 2001 04:23:42 -0400 (EDT) From: The Anarcat <anarcat@anarcat.dyndns.org> To: FreeBSD-gnats-submit@freebsd.org Subject: bin/31029: syslogd remote logging back down Message-ID: <20011004082342.A6EBC20BE1@shall.anarcat.dyndns.org>
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>Number: 31029
>Category: bin
>Synopsis: syslogd remote logging back down
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Thu Oct 04 01:30:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator: The Anarcat
>Release: FreeBSD 4.4-STABLE i386
>Organization:
Nada, inc.
>Environment:
System: FreeBSD shall.anarcat.dyndns.org 4.4-STABLE FreeBSD 4.4-STABLE #7: Sat Sep 15 00:41:38 EDT 2001 anarcat@shall.anarcat.dyndns.org:/usr/obj/usr/src/sys/SHALL i386
>Description:
From -questions:
On Tue, Oct 02, 2001 at 11:57:08AM -0400, The Anarcat wrote:
> Hi.
>
> I think I noticed what seems to me undesirable (and undocumented?)
> behavior in syslogd. When a remote logging host (@host) is
> unreachable:
>
> syslogd: sendto: Host is down
>
> syslogd *never* tries to reach it again, unless it receives a HUP.
> Shouldn't it try to reach it again, from time to time?
>
> The @host was indeed down, but when it was brought back up, remote
> logging wasn't resumed.
>How-To-Repeat:
*.* @host
where host is down or unreachable.
>Fix:
This is a draft of what I would call "approximate exponential backoff
algorithm". :)
There's a lot of debugging code that can be removed, but they help
seeing what's going on.
There's probably a better way to do this too. :)
--- syslogd.c.orig Wed Oct 3 15:56:32 2001
+++ syslogd.c Thu Oct 4 00:06:49 2001
@@ -142,6 +142,9 @@
#define MARK 0x008 /* this message is a mark */
#define ISKERNEL 0x010 /* kernel generated message */
+#define DELAY_MUL 2 /* delay multiplier */
+#define DELAY_INIT 30 /* initial delay in seconds */
+
/*
* This structure represents the files that will have log
* copies printed.
@@ -159,6 +162,9 @@
#define PRI_EQ 0x2
#define PRI_GT 0x4
char *f_program; /* program this applies to */
+ /* should this be part of the union? */
+ time_t f_unreach; /* time since last unreach */
+ time_t f_delay; /* backoff time */
union {
char f_uname[MAXUNAMES][UT_NAMESIZE+1];
struct {
@@ -999,6 +1005,15 @@
l = MAXLINE;
if (finet) {
+ dprintf("FORW: now: %d f_unreach: %d f_delay: %d\n", (int) now, (int) f->f_unreach, (int) f->f_delay);
+ /* XXX: must make sure this is initialized to 0 */
+ if (f->f_unreach) { /* there was a failure last time */
+ dprintf("another try at host\n");
+ if ( (now - f->f_unreach) < f->f_delay) {
+ dprintf("skipping: now: %d, f_unreach: %d f_delay: %d\n", (int) now, (int) f->f_unreach, (int) f->f_delay);
+ break; /* do not send */
+ }
+ }
for (r = f->f_un.f_forw.f_addr; r; r = r->ai_next) {
for (i = 0; i < *finet; i++) {
#if 0
@@ -1017,12 +1032,38 @@
if (lsent == l && !send_to_all)
break;
}
+ dprintf("lsent: %d\n", lsent);
if (lsent != l) {
int e = errno;
- (void)close(f->f_file);
- errno = e;
- f->f_type = F_UNUSED;
+ dprintf("sendto: f_unreach: %d f_delay: %d\n", (int) f->f_unreach, (int) f->f_delay);
logerror("sendto");
+ errno = e;
+ switch (errno) {
+ case EHOSTUNREACH:
+ case EHOSTDOWN:
+ if (f->f_unreach)
+ f->f_delay *= DELAY_MUL;
+ else {
+ f->f_unreach = now;
+ f->f_delay = DELAY_INIT;
+ }
+ dprintf("setting: f_unreach: %d f_delay: %d\n", (int) f->f_unreach, (int) f->f_delay);
+ break;
+ /* case EBADF: */
+ /* case EACCES: */
+ /* case ENOTSOCK: */
+ /* case EFAULT: */
+ /* case EMSGSIZE: */
+ /* case EAGAIN: */
+ /* case ENOBUFS: */
+ /* case ECONNREFUSED: */
+ default:
+ dprintf("removing entry\n", e);
+ (void)close(f->f_file);
+ errno = e;
+ f->f_type = F_UNUSED;
+ break;
+ }
}
}
break;
@@ -2301,3 +2342,7 @@
return(socks);
}
+
+/* Local Variables: *** */
+/* c-basic-offset:8 *** */
+/* End: *** */
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