$hostname variable

src/core/ngx_config.h

@@ -116,10 +116,11 @@ typedef intptr_t        ngx_flag_t;
 #define INET_ADDRSTRLEN  16
 #endif
 
-#define NGX_MAXHOSTNAMELEN 64
+#ifdef MAXHOSTNAMELEN
-/*
+#define NGX_MAXHOSTNAMELEN  MAXHOSTNAMELEN
-#define NGX_MAXHOSTNAMELEN MAXHOSTNAMELEN
+#else
-*/
+#define NGX_MAXHOSTNAMELEN  256
+#endif
 
 
 #if ((__GNU__ == 2) && (__GNUC_MINOR__ < 8))

src/core/ngx_cycle.c

@@ -57,6 +57,7 @@ ngx_init_cycle(ngx_cycle_t *old_cycle)
     ngx_listening_t     *ls, *nls;
     ngx_core_conf_t     *ccf, *old_ccf;
     ngx_core_module_t   *module;
+    char                 hostname[NGX_MAXHOSTNAMELEN];
 
     log = old_cycle->log;
 
@@ -170,6 +171,26 @@ ngx_init_cycle(ngx_cycle_t *old_cycle)
     }
 
 
+    if (gethostname(hostname, NGX_MAXHOSTNAMELEN) == -1) {
+        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "gethostname() failed");
+        ngx_destroy_pool(pool);
+        return NULL;
+    }
+
+    /* on Linux gethostname() silently truncates name that does not fit */
+
+    hostname[NGX_MAXHOSTNAMELEN - 1] = '\0';
+    cycle->hostname.len = ngx_strlen(hostname);
+
+    cycle->hostname.data = ngx_palloc(pool, cycle->hostname.len);
+    if (cycle->hostname.data == NULL) {
+        ngx_destroy_pool(pool);
+        return NULL;
+    }
+
+    ngx_memcpy(cycle->hostname.data, hostname, cycle->hostname.len);
+
+
     for (i = 0; ngx_modules[i]; i++) {
         if (ngx_modules[i]->type != NGX_CORE_MODULE) {
             continue;

src/core/ngx_cycle.h

@@ -62,6 +62,7 @@ struct ngx_cycle_s {
     ngx_str_t                 conf_file;
     ngx_str_t                 root;
     ngx_str_t                 lock_file;
+    ngx_str_t                 hostname;
 };
 
 

src/http/ngx_http_core_module.c

@@ -2606,20 +2606,7 @@ ngx_http_core_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
     }
 
     if (conf->server_name.data == NULL) {
-        conf->server_name.data = ngx_palloc(cf->pool, NGX_MAXHOSTNAMELEN);
+        conf->server_name = cf->cycle->hostname;
-        if (conf->server_name.data == NULL) {
-            return NGX_CONF_ERROR;
-        }
-
-        if (gethostname((char *) conf->server_name.data, NGX_MAXHOSTNAMELEN)
-            == -1)
-        {
-            ngx_conf_log_error(NGX_LOG_EMERG, cf, ngx_errno,
-                               "gethostname() failed");
-            return NGX_CONF_ERROR;
-        }
-
-        conf->server_name.len = ngx_strlen(conf->server_name.data);
 
         sn = ngx_array_push(&conf->server_names);
         if (sn == NULL) {

src/http/ngx_http_variables.c

@@ -75,6 +75,8 @@ static ngx_int_t ngx_http_variable_sent_transfer_encoding(ngx_http_request_t *r,
 
 static ngx_int_t ngx_http_variable_nginx_version(ngx_http_request_t *r,
     ngx_http_variable_value_t *v, uintptr_t data);
+static ngx_int_t ngx_http_variable_hostname(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data);
 
 /*
  * TODO:
@@ -221,6 +223,9 @@ static ngx_http_variable_t  ngx_http_core_variables[] = {
     { ngx_string("nginx_version"), NULL, ngx_http_variable_nginx_version,
       0, 0, 0 },
 
+    { ngx_string("hostname"), NULL, ngx_http_variable_hostname,
+      0, 0, 0 },
+
     { ngx_null_string, NULL, NULL, 0, 0, 0 }
 };
 
@@ -1272,6 +1277,20 @@ ngx_http_variable_nginx_version(ngx_http_request_t *r,
 }
 
 
+static ngx_int_t
+ngx_http_variable_hostname(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data)
+{
+    v->len = ngx_cycle->hostname.len;
+    v->valid = 1;
+    v->no_cacheable = 0;
+    v->not_found = 0;
+    v->data = ngx_cycle->hostname.data;
+
+    return NGX_OK;
+}
+
+
 ngx_int_t
 ngx_http_variables_add_core_vars(ngx_conf_t *cf)
 {

src/mail/ngx_mail_core_module.c

@@ -185,20 +185,7 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
     ngx_conf_merge_str_value(conf->server_name, prev->server_name, "");
 
     if (conf->server_name.len == 0) {
-        conf->server_name.data = ngx_palloc(cf->pool, NGX_MAXHOSTNAMELEN);
+        conf->server_name = cf->cycle->hostname;
-        if (conf->server_name.data == NULL) {
-            return NGX_CONF_ERROR;
-        }
-
-        if (gethostname((char *) conf->server_name.data, NGX_MAXHOSTNAMELEN)
-            == -1)
-        {
-            ngx_log_error(NGX_LOG_EMERG, cf->log, ngx_errno,
-                          "gethostname() failed");
-            return NGX_CONF_ERROR;
-        }
-
-        conf->server_name.len = ngx_strlen(conf->server_name.data);
     }
 
     if (conf->protocol == NULL) {