add a directive to allow filter undesired parameters

Author: wandenberg

README.md

@@ -5,6 +5,8 @@ A module to order the querystring parameters in a variable to be used as cache k
 
 Requests like /index.html?b=2&a=1&c=3, /index.html?b=2&c=3&a=1, /index.html?c=3&a=1&b=2, /index.html?c=3&b=2&a=1 will produce the same value for `$sorted_querystring_args` _'a=1&b=2&c=3'_.
 
+It is also possible remove some undesired parameter defining its name with `sorted_querysting_filter_parameter`, like `sorted_querysting_filter_parameter b _ foo;` resulting in a `$sorted_querystring_args` as _'a=1&c=3'_
+
 _This module is not distributed with the Nginx source. See [the installation instructions](#installation)._
 
 
@@ -46,6 +48,17 @@ An example:
 
       access_log       logs/nginx-http_access.log main;
 
+      location /filtered {
+        sorted_querysting_filter_parameter v _ time b;
+
+        proxy_set_header Host "static_files_server";
+        proxy_pass http://localhost:8081;
+
+        proxy_cache zone;
+        proxy_cache_key "$sorted_querystring_args";
+        proxy_cache_valid 200 1m;
+      }
+
       location / {
         proxy_pass http://localhost:8081;
 
@@ -71,6 +84,12 @@ Variables
 * **$sorted_querystring_args** - just list the IP considered as remote IP on the connection
 
 
+Directives
+----------
+
+* **sorted_querystring_filter_parameter** - list parameters to be filtered while using the `$sorted_querystring_args` variable.
+
+
 <a id="installation"></a>Installation instructions
 --------------------------------------------------
 

nginx.conf

@@ -34,6 +34,17 @@ http {
 
     access_log       logs/nginx-http_access.log main;
 
+    location /filtered {
+      sorted_querysting_filter_parameter v _ v time b;
+
+      proxy_set_header Host "static_files_server";
+      proxy_pass http://localhost:8081;
+
+      proxy_cache zone;
+      proxy_cache_key "$sorted_querystring_args";
+      proxy_cache_valid 200 1m;
+    }
+
     location / {
       proxy_pass http://localhost:8081;
 

ngx_http_sorted_querystring_module.c

@@ -5,9 +5,18 @@
 
 
 ngx_int_t    ngx_http_sorted_querystring_pre_config(ngx_conf_t *cf);
+void        *ngx_http_sorted_querystring_create_loc_conf(ngx_conf_t *cf);
+char        *ngx_http_sorted_querystring_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child);
+char        *ngx_conf_set_parameters_to_filter(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
 ngx_int_t    ngx_http_sorted_querystring_args_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data);
 ngx_int_t    ngx_http_sorted_querystring_cmp_parameters(const ngx_queue_t *one, const ngx_queue_t *two);
 
+
+typedef struct {
+    ngx_array_t              *parameters_to_filter;
+} ngx_http_sorted_querystring_loc_conf_t;
+
+
 typedef struct {
     ngx_queue_t               args_queue;
 } ngx_http_sorted_querystring_ctx_t;
@@ -31,6 +40,13 @@ static ngx_http_variable_t  ngx_http_sorted_querystring_vars[] = {
 
 
 static ngx_command_t ngx_http_sorted_querystring_commands[] = {
+    { ngx_string("sorted_querysting_filter_parameter"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF|NGX_CONF_1MORE,
+      ngx_conf_set_parameters_to_filter,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      offsetof(ngx_http_sorted_querystring_loc_conf_t, parameters_to_filter),
+      NULL },
+
     ngx_null_command
 };
 
@@ -45,8 +61,8 @@ static ngx_http_module_t ngx_http_sorted_querystring_module_ctx = {
     NULL,                                           /* create server configuration */
     NULL,                                           /* merge server configuration */
 
-    NULL,                                           /* create location configuration */
-    NULL                                            /* merge location configuration */
+    ngx_http_sorted_querystring_create_loc_conf,    /* create location configuration */
+    ngx_http_sorted_querystring_merge_loc_conf      /* merge location configuration */
 };
 
 
@@ -85,13 +101,92 @@ ngx_http_sorted_querystring_pre_config(ngx_conf_t *cf)
 }
 
 
+void *
+ngx_http_sorted_querystring_create_loc_conf(ngx_conf_t *cf)
+{
+    ngx_http_sorted_querystring_loc_conf_t  *conf;
+
+    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_sorted_querystring_loc_conf_t));
+    if (conf == NULL) {
+        return NULL;
+    }
+
+    conf->parameters_to_filter = NGX_CONF_UNSET_PTR;
+
+    return conf;
+}
+
+
+char *
+ngx_http_sorted_querystring_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
+{
+    ngx_http_sorted_querystring_loc_conf_t  *prev = parent;
+    ngx_http_sorted_querystring_loc_conf_t  *conf = child;
+
+    ngx_conf_merge_ptr_value(conf->parameters_to_filter, prev->parameters_to_filter, NULL);
+
+    return NGX_CONF_OK;
+}
+
+
+char *
+ngx_conf_set_parameters_to_filter(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    char  *p = conf;
+
+    ngx_array_t     **field;
+    ngx_str_t        *value, *s;
+    ngx_uint_t        i, j;
+    ngx_flag_t        exists;
+
+    field = (ngx_array_t **) (p + cmd->offset);
+
+    if (*field != NGX_CONF_UNSET_PTR) {
+        return "is duplicate";
+    }
+
+    *field = ngx_array_create(cf->pool, cf->args->nelts, sizeof(ngx_str_t));
+    if (*field == NULL) {
+        return NGX_CONF_ERROR;
+    }
+
+    value = cf->args->elts;
+
+    for (i = 1; i < cf->args->nelts; i++) {
+        exists = 0;
+        s = (*field)->elts;
+        for (j = 0; j < (*field)->nelts; j++) {
+            if ((value[i].len == s[j].len) && ngx_strncasecmp(value[i].data, s[j].data, value[i].len) == 0) {
+                exists = 1;
+                break;
+            }
+        }
+
+        if (!exists) {
+            s = ngx_array_push(*field);
+            if (s == NULL) {
+                return NGX_CONF_ERROR;
+            }
+
+            *s = value[i];
+        }
+    }
+
+    return NGX_CONF_OK;
+}
+
+
 ngx_int_t
 ngx_http_sorted_querystring_args_variable(ngx_http_request_t *r, ngx_http_variable_value_t *var, uintptr_t data)
 {
+    ngx_http_sorted_querystring_loc_conf_t      *sqlc = ngx_http_get_module_loc_conf(r, ngx_http_sorted_querystring_module);
     ngx_http_sorted_querystring_ctx_t           *ctx = ngx_http_get_module_ctx(r, ngx_http_sorted_querystring_module);
     ngx_http_sorted_querystring_parameter_t     *param;
     u_char                                      *p, *ampersand, *equal, *last;
     ngx_queue_t                                 *q;
+    ngx_flag_t                                   filter;
+    ngx_str_t                                   *value;
+    ngx_uint_t                                   i;
 
     if (r->args.len == 0) {
         var->len = 0;
@@ -153,7 +248,22 @@ ngx_http_sorted_querystring_args_variable(ngx_http_request_t *r, ngx_http_variab
     p = var->data;
     for (q = ngx_queue_head(&ctx->args_queue); q != ngx_queue_sentinel(&ctx->args_queue); q = ngx_queue_next(q)) {
         param = ngx_queue_data(q, ngx_http_sorted_querystring_parameter_t, queue);
-        p = ngx_sprintf(p, "%V&", &param->complete);
+
+        filter = 0;
+        if (sqlc->parameters_to_filter && (param->key.len > 0)) {
+            value = sqlc->parameters_to_filter->elts;
+            for (i = 0; i < sqlc->parameters_to_filter->nelts; i++) {
+                if ((param->key.len == value[i].len) && ngx_strncasecmp(param->key.data, value[i].data, param->key.len) == 0) {
+                    filter = 1;
+                    break;
+                }
+            }
+
+        }
+
+        if (!filter) {
+            p = ngx_sprintf(p, "%V&", &param->complete);
+        }
     }
 
     var->len = p - var->data - 1;