Hi,
When the connection to a TCP syslog server fails or the TCP connection
terminates, try to reconnect after an increasing timeout.
ok?
bluhm
Index: usr.sbin/syslogd/syslogd.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/usr.sbin/syslogd/syslogd.c,v
retrieving revision 1.140
diff -u -p -r1.140 syslogd.c
--- usr.sbin/syslogd/syslogd.c 8 Jan 2015 20:22:47 -0000 1.140
+++ usr.sbin/syslogd/syslogd.c 13 Jan 2015 22:32:36 -0000
@@ -135,6 +135,7 @@ struct filed {
/* @proto46://[hostname]:servname\0 */
struct sockaddr_storage f_addr;
struct bufferevent *f_bufev;
+ int f_reconnectwait;
} f_forw; /* forwarding address */
char f_fname[MAXPATHLEN];
struct {
@@ -265,7 +266,9 @@ void udp_readcb(int, short, void *);
void unix_readcb(int, short, void *);
int tcp_socket(struct filed *);
void tcp_readcb(struct bufferevent *, void *);
+void tcp_writecb(struct bufferevent *, void *);
void tcp_errorcb(struct bufferevent *, short, void *);
+void tcp_connectcb(int, short, void *);
void die_signalcb(int, short, void *);
void mark_timercb(int, short, void *);
void init_signalcb(int, short, void *);
@@ -716,6 +719,18 @@ tcp_readcb(struct bufferevent *bufev, vo
}
void
+tcp_writecb(struct bufferevent *bufev, void *arg)
+{
+ struct filed *f = arg;
+
+ /*
+ * Successful write, connection to server is good, reset wait time.
+ */
+ dprintf("loghost \"%s\" successful write\n", f->f_un.f_forw.f_loghost);
+ f->f_un.f_forw.f_reconnectwait = 0;
+}
+
+void
tcp_errorcb(struct bufferevent *bufev, short event, void *arg)
{
struct filed *f = arg;
@@ -731,20 +746,67 @@ tcp_errorcb(struct bufferevent *bufev, s
f->f_un.f_forw.f_loghost, strerror(errno));
dprintf("%s\n", ebuf);
+ /* The SIGHUP handler may also close the socket, so invalidate it. */
close(f->f_file);
- if ((f->f_file = tcp_socket(f)) == -1) {
- /* XXX reconnect later */
- bufferevent_free(bufev);
- f->f_type = F_UNUSED;
- } else {
- /* XXX The messages in the output buffer may be out of sync. */
- bufferevent_setfd(bufev, f->f_file);
- bufferevent_enable(f->f_un.f_forw.f_bufev, EV_READ);
- }
+ f->f_file = -1;
+
+ /*
+ * XXX The messages in the output buffer may be out of sync.
+ * Here we should clear the buffer or at least remove partial
+ * messages from the beginning.
+ */
+ tcp_connectcb(-1, 0, f);
+
+ /* Log the connection error to the fresh buffer after reconnecting. */
logmsg(LOG_SYSLOG|LOG_WARNING, ebuf, LocalHostName, ADDDATE);
}
void
+tcp_connectcb(int fd, short event, void *arg)
+{
+ struct filed *f = arg;
+ struct bufferevent *bufev = f->f_un.f_forw.f_bufev;
+ struct timeval to;
+ int s;
+
+ if ((event & EV_TIMEOUT) == 0 && f->f_un.f_forw.f_reconnectwait > 0)
+ goto retry;
+
+ /* Avoid busy reconnect loop, delay until successful write. */
+ if (f->f_un.f_forw.f_reconnectwait == 0)
+ f->f_un.f_forw.f_reconnectwait = 1;
+
+ if ((s = tcp_socket(f)) == -1)
+ goto retry;
+
+ dprintf("tcp connect callback: success, event %#x\n", event);
+ bufferevent_setfd(bufev, s);
+ bufferevent_setcb(bufev, tcp_readcb, tcp_writecb, tcp_errorcb, f);
+ /*
+ * Although syslog is a write only protocol, enable reading from
+ * the socket to detect connection close and errors.
+ */
+ bufferevent_enable(bufev, EV_READ|EV_WRITE);
+ f->f_file = s;
+
+ return;
+
+ retry:
+ f->f_un.f_forw.f_reconnectwait <<= 1;
+ if (f->f_un.f_forw.f_reconnectwait > 600)
+ f->f_un.f_forw.f_reconnectwait = 600;
+ to.tv_sec = f->f_un.f_forw.f_reconnectwait;
+ to.tv_usec = 0;
+
+ dprintf("tcp connect callback: retry, event %#x, wait %d\n",
+ event, f->f_un.f_forw.f_reconnectwait);
+ bufferevent_setfd(bufev, -1);
+ /* We can reuse the write event as bufferevent is disabled. */
+ evtimer_set(&bufev->ev_write, tcp_connectcb, f);
+ evtimer_add(&bufev->ev_write, &to);
+}
+
+void
usage(void)
{
@@ -1712,22 +1774,16 @@ cfline(char *line, char *prog)
}
f->f_type = F_FORWUDP;
} else if (strncmp(proto, "tcp", 3) == 0) {
- int s;
-
- if ((s = tcp_socket(f)) == -1)
- break;
- if ((f->f_un.f_forw.f_bufev = bufferevent_new(s,
- tcp_readcb, NULL, tcp_errorcb, f)) == NULL) {
+ if ((f->f_un.f_forw.f_bufev = bufferevent_new(-1,
+ tcp_readcb, tcp_writecb, tcp_errorcb, f)) == NULL) {
snprintf(ebuf, sizeof(ebuf),
"bufferevent \"%s\"",
f->f_un.f_forw.f_loghost);
logerror(ebuf);
- close(s);
break;
}
- bufferevent_enable(f->f_un.f_forw.f_bufev, EV_READ);
- f->f_file = s;
f->f_type = F_FORWTCP;
+ tcp_connectcb(-1, 0, f);
}
break;
