Syslog: introduced error log handler.

This ensures that errors which happen during logging to syslog are logged
with proper context, such as "while logging to syslog" and the server name.

Prodded by Safar Safarly.

diff --git a/src/core/ngx_syslog.c b/src/core/ngx_syslog.c
index 0a64e10b8de5245dad5d0dc3c2e03cb134e2b155..bad45bd16b22def599d30150f333251e2c6ceaa5 100644 (file)
--- a/src/core/ngx_syslog.c
+++ b/src/core/ngx_syslog.c
@@ -18,6 +18,7 @@
 static char *ngx_syslog_parse_args(ngx_conf_t *cf, ngx_syslog_peer_t *peer);
 static ngx_int_t ngx_syslog_init_peer(ngx_syslog_peer_t *peer);
 static void ngx_syslog_cleanup(void *data);
+static u_char *ngx_syslog_log_error(ngx_log_t *log, u_char *buf, size_t len);
 
 
 static char  *facilities[] = {
@@ -67,7 +68,7 @@ ngx_syslog_process_conf(ngx_conf_t *cf, ngx_syslog_peer_t *peer)
     }
 
     peer->hostname = &cf->cycle->hostname;
-    peer->log = &cf->cycle->new_log;
+    peer->logp = &cf->cycle->new_log;
 
     peer->conn.fd = (ngx_socket_t) -1;
 
@@ -289,6 +290,13 @@ ngx_syslog_send(ngx_syslog_peer_t *peer, u_char *buf, size_t len)
 {
     ssize_t  n;
 
+    if (peer->log.handler == NULL) {
+        peer->log = *peer->logp;
+        peer->log.handler = ngx_syslog_log_error;
+        peer->log.data = peer;
+        peer->log.action = "logging to syslog";
+    }
+
     if (peer->conn.fd == (ngx_socket_t) -1) {
         if (ngx_syslog_init_peer(peer) != NGX_OK) {
             return NGX_ERROR;
@@ -306,7 +314,7 @@ 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, peer->log, ngx_socket_errno,
+            ngx_log_error(NGX_LOG_ALERT, &peer->log, ngx_socket_errno,
                           ngx_close_socket_n " failed");
         }
 
@@ -324,25 +332,25 @@ 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, peer->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, peer->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, peer->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;
+    peer->conn.log = &peer->log;
 
     /* UDP sockets are always ready to write */
     peer->conn.write->ready = 1;
@@ -352,7 +360,7 @@ ngx_syslog_init_peer(ngx_syslog_peer_t *peer)
 failed:
 
     if (ngx_close_socket(fd) == -1) {
-        ngx_log_error(NGX_LOG_ALERT, peer->log, ngx_socket_errno,
+        ngx_log_error(NGX_LOG_ALERT, &peer->log, ngx_socket_errno,
                       ngx_close_socket_n " failed");
     }
 
@@ -373,7 +381,30 @@ ngx_syslog_cleanup(void *data)
     }
 
     if (ngx_close_socket(peer->conn.fd) == -1) {
-        ngx_log_error(NGX_LOG_ALERT, peer->log, ngx_socket_errno,
+        ngx_log_error(NGX_LOG_ALERT, &peer->log, ngx_socket_errno,
                       ngx_close_socket_n " failed");
     }
 }
+
+
+static u_char *
+ngx_syslog_log_error(ngx_log_t *log, u_char *buf, size_t len)
+{
+    u_char             *p;
+    ngx_syslog_peer_t  *peer;
+
+    p = buf;
+
+    if (log->action) {
+        p = ngx_snprintf(buf, len, " while %s", log->action);
+        len -= p - buf;
+    }
+
+    peer = log->data;
+
+    if (peer) {
+        p = ngx_snprintf(p, len, ", server: %V", &peer->server.name);
+    }
+
+    return p;
+}

diff --git a/src/core/ngx_syslog.h b/src/core/ngx_syslog.h
index 181ebe7b30433562742ed491c51fed81150c1ae1..e2d54acdb801f6e42b599f12d00faa117323c4fe 100644 (file)
--- a/src/core/ngx_syslog.h
+++ b/src/core/ngx_syslog.h
@@ -18,7 +18,8 @@ typedef struct {
     ngx_addr_t         server;
     ngx_connection_t   conn;
 
-    ngx_log_t         *log;
+    ngx_log_t          log;
+    ngx_log_t         *logp;
 
     unsigned           busy:1;
     unsigned           nohostname:1;