fix(routing): keep encoded "?" in path for backends with a path

CHANGELOG.md

@@ -28,6 +28,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Set request timeout for OIDC query. [PR #1601](https://github.com/3scale/APIcast/pull/1601) [THREESCALE-8006](https://redhat.atlassian.net/browse/THREESCALE-8006)
 - Set upstream metrics when sending request via proxy. [PR #1598](https://github.com/3scale/APIcast/pull/1598) [THREESCALE-10571](https://redhat.atlassian.net/browse/THREESCALE-15071)
 - Certificate is never verified in API request for https backend via proxy [PR #1573](https://github.com/3scale/APIcast/pull/1568) [THREESCALE-11944](https://redhat.atlassian.net/browse/THREESCALE-11944)
+- Routing Policy: keep an encoded "?" (`%3F`) in the path when the backend has a path [PR #1613](https://github.com/3scale/APIcast/pull/1613) [Issue #1612](https://github.com/3scale/APIcast/issues/1612)
 
 ### Added
 - Update APIcast schema manifest [PR #1550](https://github.com/3scale/APIcast/pull/1550)

gateway/src/apicast/upstream.lua

@@ -8,6 +8,7 @@
 
 local setmetatable = setmetatable
 local str_format = string.format
+local str_find = string.find
 
 local resty_resolver = require('resty.resolver')
 local resty_url = require('resty.url')
@@ -121,7 +122,17 @@ function _M:set_path(path)
 end
 
 function _M:append_path(path)
-    local tmp_path, tmp_query = url_helper.split_path(path)
+    local tmp_path, tmp_query
+
+    -- ngx.var.uri is decoded, so a "?" in it was sent as "%3F" and is part of a
+    -- path segment. A path rendered from it must not be split there.
+    local uri = ngx.var.uri
+    if uri and str_find(uri, '?', 1, true) then
+      tmp_path = path
+    else
+      tmp_path, tmp_query = url_helper.split_path(path)
+    end
+
     if not self.uri.path then
       self.uri.path = "/"
     end

spec/upstream_spec.lua

@@ -53,6 +53,8 @@ describe('Upstream', function()
     end)
 
     describe(':append_path', function()
+        before_each(function() ngx.var = { } end)
+
         it('return valid path when is not set', function()
             local up = Upstream.new('http://host:8090')
             up:append_path("/test")
@@ -71,6 +73,22 @@ describe('Upstream', function()
             assert.same(up.uri.path, "/test")
         end)
 
+        it('keeps an encoded "?" of the request path in the path', function()
+            ngx.var = { uri = '/REST/svc/files/a?b' }
+            local up = Upstream.new('http://host:8090/REST/svc')
+            up:append_path("/files/a?b")
+            assert.same(up.uri.path, "/REST/svc/files/a?b")
+            assert.is_nil(up.uri.query)
+        end)
+
+        it('does not use the query of the rendered path', function()
+            ngx.var = { uri = '/REST/svc/files/a' }
+            local up = Upstream.new('http://host:8090/REST/svc')
+            up:append_path("/files/a?b")
+            assert.same(up.uri.path, "/REST/svc/files/a")
+            assert.is_nil(up.uri.query)
+        end)
+
     end)
 
     local function stub_ngx_request()

t/apicast-policy-routing.t

@@ -2586,3 +2586,54 @@ content_by_lua_block {
 }
 --- no_error_log
 [error]
+
+
+=== TEST 37: Encoded "?" in the path is kept when the backend has a path
+The rule is the one 3scale generates for a Backend used with a path. A "%3F"
+in the request path must reach the upstream as "%3F" and not cut the path.
+--- configuration
+{
+  "services": [
+    {
+      "id": 42,
+      "proxy": {
+        "policy_chain": [
+          {
+            "name": "apicast.policy.routing",
+            "configuration": {
+              "rules": [
+                {
+                  "url": "http://test:$TEST_NGINX_SERVER_PORT/REST/svc",
+                  "replace_path": "{{uri | remove_first: '/REST/svc'}}",
+                  "condition": {
+                    "operations": [
+                      {
+                        "match": "path",
+                        "op": "matches",
+                        "value": "^(/REST/svc/.*|/REST/svc/?)"
+                      }
+                    ]
+                  }
+                }
+              ]
+            }
+          }
+        ]
+      }
+    }
+  ]
+}
+--- upstream
+  location ~ / {
+     content_by_lua_block {
+       ngx.say(ngx.var.request_uri)
+     }
+  }
+--- request eval
+["GET /REST/svc/files/a%3Fb", "GET /REST/svc/files/a%3Fb?x=1", "GET /REST/svc/files/a?x=1"]
+--- response_body eval
+["/REST/svc/files/a%3Fb\n", "/REST/svc/files/a%3Fb?x=1\n", "/REST/svc/files/a?x=1\n"]
+--- error_code eval
+[200, 200, 200]
+--- no_error_log
+[error]