feat(proxy-rewrite): support NGINX variables in regex_uri

apisix/plugins/proxy-rewrite.lua

@@ -22,9 +22,11 @@ local ipairs      = ipairs
 local ngx         = ngx
 local type        = type
 local re_sub      = ngx.re.sub
+local re_gsub     = ngx.re.gsub
 local re_match    = ngx.re.match
 local req_set_uri = ngx.req.set_uri
 local sub_str     = string.sub
+local str_gsub    = string.gsub
 local str_find    = core.string.find
 
 local switch_map = {GET = ngx.HTTP_GET, POST = ngx.HTTP_POST, PUT = ngx.HTTP_PUT,
@@ -44,6 +46,26 @@ local lrucache = core.lrucache.new({
     type = "plugin",
 })
 
+local nginx_var_pattern = [[(?<!\$)\$(?=[a-zA-Z_]|\{\s*[a-zA-Z_])]]
+
+
+local function escape_nginx_vars(replacement)
+    local escaped, _, err = re_gsub(replacement, nginx_var_pattern, function()
+        return "$$"
+    end, "jo")
+    return escaped, err
+end
+
+
+local function preserve_literal_dollars(replacement)
+    return str_gsub(replacement, "%$%$", "\\$")
+end
+
+
+local function restore_literal_dollars(replacement)
+    return str_gsub(replacement, "\\%$", "$")
+end
+
 core.ctx.register_var("proxy_rewrite_regex_uri_captures", function(ctx)
     return ctx.proxy_rewrite_regex_uri_captures
 end)
@@ -225,6 +247,16 @@ function _M.check_schema(conf)
             if not secret.is_secret_ref(pattern) then
                 local test_replacement = secret.is_secret_ref(replacement)
                                          and "" or replacement
+                if test_replacement ~= "" then
+                    -- Keep validating PCRE captures without treating NGINX
+                    -- variables in the replacement as named captures.
+                    local err
+                    test_replacement, err = escape_nginx_vars(test_replacement)
+                    if err then
+                        return false, "invalid regex_uri replacement(" ..
+                            replacement .. "): " .. err
+                    end
+                end
                 local _, _, err = re_sub("/fake_uri", pattern,
                     test_replacement, "jo")
                 if err then
@@ -355,8 +387,14 @@ function _M.rewrite(conf, ctx)
             if captures then
                 ctx.proxy_rewrite_regex_uri_captures = captures
 
+                local replacement = preserve_literal_dollars(conf.regex_uri[i + 1])
+                replacement = core.utils.resolve_var_with_captures(replacement, captures)
+                replacement = core.utils.resolve_var(replacement, ctx.var, escape_separator)
+                replacement = restore_literal_dollars(replacement)
                 local uri, _, err = re_sub(upstream_uri,
-                    conf.regex_uri[i], conf.regex_uri[i + 1], "jo")
+                    conf.regex_uri[i], function()
+                        return replacement
+                    end, "jo")
                 if uri then
                     upstream_uri = uri
                 else

docs/en/latest/plugins/proxy-rewrite.md

@@ -42,7 +42,7 @@ The `proxy-rewrite` Plugin offers options to rewrite requests that APISIX forwar
 |-----------------------------|---------------|----------|---------|----------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | uri                         | string        | False    |         |                                                                                                                                        |  New Upstream URI path. Value supports [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html). For example, `$arg_name`.                                                                                                                                                                                                                                                                                                                       |
 | method                      | string        | False    |         | ["GET", "POST", "PUT", "HEAD", "DELETE", "OPTIONS", "MKCOL", "COPY", "MOVE", "PROPFIND", "LOCK", "UNLOCK", "PATCH", "TRACE"] | HTTP method to rewrite requests to use.                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
-| regex_uri                   | array[string] | False    |         |                                                                                                                                        | Regular expressions used to match the URI path from client requests and compose a new Upstream URI path. When both `uri` and `regex_uri` are configured, `uri` has a higher priority. The array should contain one or more **key-value pairs**, with the key being the regular expression to match URI against and value being the new Upstream URI path. For example, with `["^/iresty/(. *)/(. *)", "/$1-$2", ^/theothers/*", "/theothers"]`, if a request is originally sent to `/iresty/hello/world`, the Plugin will rewrite the Upstream URI path to `/iresty/hello-world`; if a request is originally sent to `/theothers/hello/world`, the Plugin will rewrite the Upstream URI path to `/theothers`. |
+| regex_uri                   | array[string] | False    |         |                                                                                                                                        | Regular expressions used to match the URI path from client requests and compose a new Upstream URI path. The replacement supports both regular expression captures such as `$1` and [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html) such as `$arg_name`. When both `uri` and `regex_uri` are configured, `uri` has a higher priority. The array should contain one or more **key-value pairs**, with the key being the regular expression to match URI against and value being the new Upstream URI path. For example, with `["^/iresty/(. *)/(. *)", "/$1-$2", ^/theothers/*", "/theothers"]`, if a request is originally sent to `/iresty/hello/world`, the Plugin will rewrite the Upstream URI path to `/iresty/hello-world`; if a request is originally sent to `/theothers/hello/world`, the Plugin will rewrite the Upstream URI path to `/theothers`. |
 | host                        | string        | False    |         |                                                                                                                                        | Set [`Host`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Host) request header.                                                                                                                                                                                                                                                                                                                                                                                                                                 |
 | headers                     | object        | False    |         |                                                                                                                                   |   Header actions to be executed. Can be set to objects of action verbs `add`, `remove`, and/or `set`; or an object consisting of headers to be `set`. When multiple action verbs are configured, actions are executed in the order of `add`, `remove`, and `set`.                |
 | headers.add     | object   | False     |        |                 | Headers to append to requests. If a header already present in the request, the header value will be appended. Header value could be set to a constant, one or more [NGINX variables](https://nginx.org/en/docs/http/ngx_http_core_module.html), or the matched result of `regex_uri` using variables such as `$1-$2-$3`. A value could also be an array of such values (e.g. `["val1", "val2"]`) to append the header multiple times, resulting in multiple headers with the same name.                                                                                              |

docs/zh/latest/plugins/proxy-rewrite.md

@@ -42,7 +42,7 @@ description: proxy-rewrite 插件支持重写 APISIX 转发到上游服务的请
 |-----------------------------|-----------|----------|---------|------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | uri | string | 否 | | | 新的上游 URI 路径。值支持 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。例如，`$arg_name`。 |
 | method | string | 否 | | ["GET", "POST", "PUT", "HEAD", "DELETE", "OPTIONS", "MKCOL", "COPY", "MOVE", "PROPFIND", "LOCK", "UNLOCK", "PATCH", "TRACE"] | 要使用的重写请求的 HTTP 方法。 |
-| regex_uri | array[string] | 否 | | | 用于匹配客户端请求的 URI 路径并组成新的上游 URI 路径的正则表达式。当同时配置 `uri` 和 `regex_uri` 时，`uri` 具有更高的优先级。该数组应包含一个或多个 **键值对**，其中键是用于匹配 URI 的正则表达式，值是新的上游 URI 路径。例如，对于 `["^/iresty/(. *)/(. *)", "/$1-$2", ^/theothers/*", "/theothers"]`，如果请求最初发送到 `/iresty/hello/world`，插件会将上游 URI 路径重写为 `/iresty/hello-world`；如果请求最初发送到 `/theothers/hello/world`，插件会将上游 URI 路径重写为 `/theothers`。|
+| regex_uri | array[string] | 否 | | | 用于匹配客户端请求的 URI 路径并组成新的上游 URI 路径的正则表达式。替换字符串同时支持 `$1` 等正则捕获和 `$arg_name` 等 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)。当同时配置 `uri` 和 `regex_uri` 时，`uri` 具有更高的优先级。该数组应包含一个或多个 **键值对**，其中键是用于匹配 URI 的正则表达式，值是新的上游 URI 路径。例如，对于 `["^/iresty/(. *)/(. *)", "/$1-$2", ^/theothers/*", "/theothers"]`，如果请求最初发送到 `/iresty/hello/world`，插件会将上游 URI 路径重写为 `/iresty/hello-world`；如果请求最初发送到 `/theothers/hello/world`，插件会将上游 URI 路径重写为 `/theothers`。|
 | host | string | 否 | | | 设置 [`Host`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Host) 请求标头。|
 | headers | object | 否 | | | 要执行的标头操作。可以设置为动作动词 `add`、`remove` 和/或 `set` 的对象；或由要 `set` 的标头组成的对象。当配置了多个动作动词时，动作将按照“添加”、“删除”和“设置”的顺序执行。|
 | headers.add | object | 否 | | | 要附加到请求的标头。如果请求中已经存在标头，则会附加标头值。标头值可以设置为常量、一个或多个 [NGINX 变量](https://nginx.org/en/docs/http/ngx_http_core_module.html)，或者 `regex_uri` 的匹配结果（使用变量，例如 `$1-$2-$3`）。标头值也可以是上述值的数组（例如 `["val1", "val2"]`），从而多次附加该标头，生成多个同名标头。|

t/plugin/proxy-rewrite4.t

@@ -0,0 +1,82 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+BEGIN {
+    if ($ENV{TEST_NGINX_CHECK_LEAK}) {
+        $SkipReason = "unavailable for the hup tests";
+
+    } else {
+        $ENV{TEST_NGINX_USE_HUP} = 1;
+        undef $ENV{TEST_NGINX_USE_STAP};
+    }
+}
+
+use t::APISIX 'no_plan';
+
+repeat_each(1);
+no_long_string();
+no_shuffle();
+no_root_location();
+run_tests;
+
+__DATA__
+
+=== TEST 1: set route(regex_uri with capture and NGINX variable)
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/routes/1',
+                 ngx.HTTP_PUT,
+                 [[{
+                        "plugins": {
+                            "proxy-rewrite": {
+                                "regex_uri": ["^/api/(.*)$",
+                                              "/plugin_proxy_rewrite_args?c=$1&n=$arg_name&l=$$x"]
+                            }
+                        },
+                        "upstream": {
+                            "nodes": {
+                                "127.0.0.1:1980": 1
+                            },
+                            "type": "roundrobin"
+                        },
+                        "uri": "/api/*"
+                }]]
+                )
+
+            if code >= 300 then
+                ngx.status = code
+            end
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
+
+
+
+=== TEST 2: hit route(regex_uri resolves capture and NGINX variable)
+--- request
+GET /api/team?name=alice HTTP/1.1
+--- response_body
+uri: /plugin_proxy_rewrite_args
+c: team
+l: $x
+n: alice
+name: alice