[git commit master 1/1] syslogd: close/re-resolve/reopen remote sockets on some sendto() errors

[Denys Vlasenko]

commit: http://git.busybox.net/busybox/commit/?id=e74d79866c6d125527e3ba69245a087a28fd19ce
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

function                                             old     new   delta
syslogd_main                                        1201    1262     +61

Signed-off-by: Daniel Dickinson <cshore at csolve.net>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 sysklogd/syslogd.c |   26 ++++++++++++++++++++------
 1 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 6bc450b..37a119b 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -546,7 +546,7 @@ static int try_to_resolve_remote(remoteHost_t *rh)
 		if (!rh->remoteAddr)
 			return -1;
 	}
-	return socket(rh->remoteAddr->u.sa.sa_family, SOCK_DGRAM, 0);
+	return xsocket(rh->remoteAddr->u.sa.sa_family, SOCK_DGRAM, 0);
 }
 #endif
 
@@ -636,11 +636,25 @@ static void do_syslogd(void)
 				if (rh->remoteFD == -1)
 					continue;
 			}
-			/* Send message to remote logger, ignore possible error */
-			/* TODO: on some errors, close and set G.remoteFD to -1
-			 * so that DNS resolution and connect is retried? */
-			sendto(rh->remoteFD, recvbuf, sz+1, MSG_DONTWAIT,
-				&(rh->remoteAddr->u.sa), rh->remoteAddr->len);
+
+			/* Send message to remote logger.
+			 * On some errors, close and set remoteFD to -1
+			 * so that DNS resolution is retried.
+			 */
+			if (sendto(rh->remoteFD, recvbuf, sz+1,
+					MSG_DONTWAIT | MSG_NOSIGNAL,
+					&(rh->remoteAddr->u.sa), rh->remoteAddr->len) == -1
+			) {
+				switch (errno) {
+				case ECONNRESET:
+				case ENOTCONN: /* paranoia */
+				case EPIPE:
+					close(rh->remoteFD);
+					rh->remoteFD = -1;
+					free(rh->remoteAddr);
+					rh->remoteAddr = NULL;
+				}
+			}
 		}
 #endif
 		if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
-- 
1.7.1