Syslog: removed usage of ngx_cycle->log and ngx_cycle->hostname.

During initial startup the ngx_cycle->hostname is not available, and
previously this resulted in incorrect logging.  Instead, hostname from the
configuration being parsed is now preserved in the syslog peer structure
and then used during logging.

Similarly, ngx_cycle->log might not match the configuration where the
syslog peer is defined if the configuration is not yet fully applied,
and previously this resulted in unexpected logging of syslog errors
and debug information.  Instead, cf->cycle->new_log is now referenced
in the syslog peer structure and used for logging, similarly to how it
is done in other modules.

src/core/ngx_syslog.c

@@ -66,6 +66,9 @@ ngx_syslog_process_conf(ngx_conf_t *cf, ngx_syslog_peer_t *peer)
         ngx_str_set(&peer->tag, "nginx");
     }
 
+    peer->hostname = &cf->cycle->hostname;
+    peer->log = &cf->cycle->new_log;
+
     peer->conn.fd = (ngx_socket_t) -1;
 
     peer->conn.read = &ngx_syslog_dummy_event;
@@ -243,7 +246,7 @@ ngx_syslog_add_header(ngx_syslog_peer_t *peer, u_char *buf)
     }
 
     return ngx_sprintf(buf, "<%ui>%V %V %V: ", pri, &ngx_cached_syslog_time,
-                       &ngx_cycle->hostname, &peer->tag);
+                       peer->hostname, &peer->tag);
 }
 
 
@@ -292,9 +295,6 @@ ngx_syslog_send(ngx_syslog_peer_t *peer, u_char *buf, size_t len)
         }
     }
 
-    /* log syslog socket events with valid log */
-    peer->conn.log = ngx_cycle->log;
-
     if (ngx_send) {
         n = ngx_send(&peer->conn, buf, len);
 
@@ -306,7 +306,7 @@ ngx_syslog_send(ngx_syslog_peer_t *peer, u_char *buf, size_t len)
     if (n == NGX_ERROR) {
 
         if (ngx_close_socket(peer->conn.fd) == -1) {
-            ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
+            ngx_log_error(NGX_LOG_ALERT, peer->log, ngx_socket_errno,
                           ngx_close_socket_n " failed");
         }
 
@@ -324,24 +324,25 @@ ngx_syslog_init_peer(ngx_syslog_peer_t *peer)
 
     fd = ngx_socket(peer->server.sockaddr->sa_family, SOCK_DGRAM, 0);
     if (fd == (ngx_socket_t) -1) {
-        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
+        ngx_log_error(NGX_LOG_ALERT, peer->log, ngx_socket_errno,
                       ngx_socket_n " failed");
         return NGX_ERROR;
     }
 
     if (ngx_nonblocking(fd) == -1) {
-        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
+        ngx_log_error(NGX_LOG_ALERT, peer->log, ngx_socket_errno,
                       ngx_nonblocking_n " failed");
         goto failed;
     }
 
     if (connect(fd, peer->server.sockaddr, peer->server.socklen) == -1) {
-        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
+        ngx_log_error(NGX_LOG_ALERT, peer->log, ngx_socket_errno,
                       "connect() failed");
         goto failed;
     }
 
     peer->conn.fd = fd;
+    peer->conn.log = peer->log;
 
     /* UDP sockets are always ready to write */
     peer->conn.write->ready = 1;
@@ -351,7 +352,7 @@ ngx_syslog_init_peer(ngx_syslog_peer_t *peer)
 failed:
 
     if (ngx_close_socket(fd) == -1) {
-        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
+        ngx_log_error(NGX_LOG_ALERT, peer->log, ngx_socket_errno,
                       ngx_close_socket_n " failed");
     }
 
@@ -372,7 +373,7 @@ ngx_syslog_cleanup(void *data)
     }
 
     if (ngx_close_socket(peer->conn.fd) == -1) {
-        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_socket_errno,
+        ngx_log_error(NGX_LOG_ALERT, peer->log, ngx_socket_errno,
                       ngx_close_socket_n " failed");
     }
 }

src/core/ngx_syslog.h

@@ -9,14 +9,19 @@
 
 
 typedef struct {
-    ngx_uint_t        facility;
-    ngx_uint_t        severity;
-    ngx_str_t         tag;
-
-    ngx_addr_t        server;
-    ngx_connection_t  conn;
-    unsigned          busy:1;
-    unsigned          nohostname:1;
+    ngx_uint_t         facility;
+    ngx_uint_t         severity;
+    ngx_str_t          tag;
+
+    ngx_str_t         *hostname;
+
+    ngx_addr_t         server;
+    ngx_connection_t   conn;
+
+    ngx_log_t         *log;
+
+    unsigned           busy:1;
+    unsigned           nohostname:1;
 } ngx_syslog_peer_t;