Fix of rbtree lookup on hash collisions.

Previous code incorrectly assumed that nodes with identical keys are linked
together.  This might not be true after tree rebalance.

Patch by Lanshun Zhou.

1 files changed, 24 insertions, 29 deletions

diff --git a/src/http/modules/ngx_http_limit_req_module.c b/src/http/modules/ngx_http_limit_req_module.c
index e4d90a98f..f1698a394 100644
--- a/src/http/modules/ngx_http_limit_req_module.c
+++ b/src/http/modules/ngx_http_limit_req_module.c
@@ -385,47 +385,42 @@ ngx_http_limit_req_lookup(ngx_http_limit_req_limit_t *limit, ngx_uint_t hash,
 
         /* hash == node->key */
 
-        do {
-            lr = (ngx_http_limit_req_node_t *) &node->color;
+        lr = (ngx_http_limit_req_node_t *) &node->color;
 
-            rc = ngx_memn2cmp(data, lr->data, len, (size_t) lr->len);
+        rc = ngx_memn2cmp(data, lr->data, len, (size_t) lr->len);
 
-            if (rc == 0) {
-                ngx_queue_remove(&lr->queue);
-                ngx_queue_insert_head(&ctx->sh->queue, &lr->queue);
+        if (rc == 0) {
+            ngx_queue_remove(&lr->queue);
+            ngx_queue_insert_head(&ctx->sh->queue, &lr->queue);
 
-                ms = (ngx_msec_int_t) (now - lr->last);
-
-                excess = lr->excess - ctx->rate * ngx_abs(ms) / 1000 + 1000;
-
-                if (excess < 0) {
-                    excess = 0;
-                }
-
-                *ep = excess;
+            ms = (ngx_msec_int_t) (now - lr->last);
 
-                if ((ngx_uint_t) excess > limit->burst) {
-                    return NGX_BUSY;
-                }
+            excess = lr->excess - ctx->rate * ngx_abs(ms) / 1000 + 1000;
 
-                if (account) {
-                    lr->excess = excess;
-                    lr->last = now;
-                    return NGX_OK;
-                }
+            if (excess < 0) {
+                excess = 0;
+            }
 
-                lr->count++;
+            *ep = excess;
 
-                ctx->node = lr;
+            if ((ngx_uint_t) excess > limit->burst) {
+                return NGX_BUSY;
+            }
 
-                return NGX_AGAIN;
+            if (account) {
+                lr->excess = excess;
+                lr->last = now;
+                return NGX_OK;
             }
 
-            node = (rc < 0) ? node->left : node->right;
+            lr->count++;
 
-        } while (node != sentinel && hash == node->key);
+            ctx->node = lr;
+
+            return NGX_AGAIN;
+        }
 
-        break;
+        node = (rc < 0) ? node->left : node->right;
     }
 
     *ep = 0;