[nginx] Realip: fixed duplicate processing on redirects (ticket #1098).

[Maxim Dounin]

details:   http://hg.nginx.org/nginx/rev/cecf415643d7
branches:  
changeset: 6729:cecf415643d7
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Thu Oct 06 23:16:05 2016 +0300
description:
Realip: fixed duplicate processing on redirects (ticket #1098).

Duplicate processing was possible if the address set by realip was
listed in set_realip_from, and there was an internal redirect so module
context was cleared.  This resulted in exactly the same address being set,
so this wasn't a problem before the $realip_remote_addr variable was
introduced, though now results in incorrect $realip_remote_addr being
picked.

Fix is to use ngx_http_realip_get_module_ctx() to look up module context
even if it was cleared.  Additionally, the order of checks was switched to
check the configuration first as it looks more effective.

diffstat:

 src/http/modules/ngx_http_realip_module.c |  8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diffs (23 lines):

diff --git a/src/http/modules/ngx_http_realip_module.c b/src/http/modules/ngx_http_realip_module.c
--- a/src/http/modules/ngx_http_realip_module.c
+++ b/src/http/modules/ngx_http_realip_module.c
@@ -141,15 +141,15 @@ ngx_http_realip_handler(ngx_http_request
     ngx_http_realip_ctx_t       *ctx;
     ngx_http_realip_loc_conf_t  *rlcf;
 
-    ctx = ngx_http_get_module_ctx(r, ngx_http_realip_module);
+    rlcf = ngx_http_get_module_loc_conf(r, ngx_http_realip_module);
 
-    if (ctx) {
+    if (rlcf->from == NULL) {
         return NGX_DECLINED;
     }
 
-    rlcf = ngx_http_get_module_loc_conf(r, ngx_http_realip_module);
+    ctx = ngx_http_realip_get_module_ctx(r);
 
-    if (rlcf->from == NULL) {
+    if (ctx) {
         return NGX_DECLINED;
     }