syslogd: close/re-resolve/reopen remote sockets on some sendto() errors

function                                             old     new   delta
syslogd_main                                        1201    1262     +61

Signed-off-by: Daniel Dickinson <cshore@csolve.net>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 20 insertions, 6 deletions

diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 6bc450bf9..37a119b3d 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)) {