fix(tools.uri) normalization function excessive percent decoding

### Summary

This is alternative to PR #8139 where we actually fix the normalization
function to not do excessive percent-decoding on normalization.

kong/runloop/handler.lua

@@ -39,7 +39,6 @@ local subsystem    = ngx.config.subsystem
 local clear_header = ngx.req.clear_header
 local http_version = ngx.req.http_version
 local unpack       = unpack
-local escape       = require("kong.tools.uri").escape
 
 
 local is_http_module   = subsystem == "http"
@@ -1337,7 +1336,7 @@ return {
       --       router, which might have truncated it (`strip_uri`).
       -- `host` is the original header to be preserved if set.
       var.upstream_scheme = match_t.upstream_scheme -- COMPAT: pdk
-      var.upstream_uri    = escape(match_t.upstream_uri)
+      var.upstream_uri    = match_t.upstream_uri
       if match_t.upstream_host then
         var.upstream_host = match_t.upstream_host
       end

kong/tools/uri.lua

@@ -1,6 +1,3 @@
-local _M = {}
-
-
 local string_char = string.char
 local string_upper = string.upper
 local string_find = string.find
@@ -35,6 +32,7 @@ local RESERVED_CHARACTERS = {
   [0x5D] = true, -- ]
 }
 
+
 local ESCAPE_PATTERN = "[^!#$&'()*+,/:;=?@[\\]A-Z\\d-_.~%]"
 
 local TMP_OUTPUT = require("table.new")(16, 0)
@@ -52,12 +50,21 @@ local function percent_decode(m)
 end
 
 
-local function escape(m)
+local function percent_escape(m)
   return string_format("%%%02X", string_byte(m[0]))
 end
 
 
-function _M.normalize(uri, merge_slashes)
+local function escape(uri)
+  if ngx_re_find(uri, ESCAPE_PATTERN, "joi") then
+    return ngx_re_gsub(uri, ESCAPE_PATTERN, percent_escape, "joi")
+  end
+
+  return uri
+end
+
+
+local function unescape(uri, merge_slashes)
   -- check for simple cases and early exit
   if uri == "" or uri == "/" then
     return uri
@@ -148,13 +155,13 @@ function _M.normalize(uri, merge_slashes)
 end
 
 
-function _M.escape(uri)
-  if ngx_re_find(uri, ESCAPE_PATTERN, "joi") then
-    return ngx_re_gsub(uri, ESCAPE_PATTERN, escape, "joi")
-  end
-
-  return uri
+local function normalize(uri, merge_slashes)
+  return escape(unescape(uri, merge_slashes))
 end
 
 
-return _M
+return {
+  escape = escape,
+  unescape = unescape,
+  normalize = normalize,
+}

spec/01-unit/08-router_spec.lua

@@ -2494,6 +2494,44 @@ describe("Router", function()
       assert.equal(2, #match_t.matches.uri_captures)
     end)
 
+    it("returns uri_captures normalized, fix #7913", function()
+      local use_case = {
+        {
+          service = service,
+          route   = {
+            paths = { [[/users/(?P<fullname>[a-zA-Z\s\d%]+)/profile/?(?P<scope>[a-z]*)]] },
+          },
+        },
+      }
+
+      local router = assert(Router.new(use_case))
+      local _ngx = mock_ngx("GET", "/users/%6aohn%20doe/profile", { host = "domain.org" })
+
+      router._set_ngx(_ngx)
+      local match_t = router.exec()
+      assert.equal("john%20doe", match_t.matches.uri_captures[1])
+      assert.equal("john%20doe", match_t.matches.uri_captures.fullname)
+      assert.equal("",     match_t.matches.uri_captures[2])
+      assert.equal("",     match_t.matches.uri_captures.scope)
+      -- returns the full match as well
+      assert.equal("/users/john%20doe/profile", match_t.matches.uri_captures[0])
+      -- no stripped_uri capture
+      assert.is_nil(match_t.matches.uri_captures.stripped_uri)
+      assert.equal(2, #match_t.matches.uri_captures)
+
+      -- again, this time from the LRU cache
+      local match_t = router.exec()
+      assert.equal("john%20doe", match_t.matches.uri_captures[1])
+      assert.equal("john%20doe", match_t.matches.uri_captures.fullname)
+      assert.equal("",     match_t.matches.uri_captures[2])
+      assert.equal("",     match_t.matches.uri_captures.scope)
+      -- returns the full match as well
+      assert.equal("/users/john%20doe/profile", match_t.matches.uri_captures[0])
+      -- no stripped_uri capture
+      assert.is_nil(match_t.matches.uri_captures.stripped_uri)
+      assert.equal(2, #match_t.matches.uri_captures)
+    end)
+
     it("returns no uri_captures from a [uri prefix] match", function()
       local use_case = {
         {

spec/01-unit/18-tools_uri_spec.lua

@@ -47,8 +47,12 @@ describe("kong.tools.uri", function()
       assert.equal("/a/b/", uri.normalize("/a//b//", true))
     end)
 
-    it("decodes non-ASCII characters that are unreserved, issue #2366", function()
-      assert.equal("/endeløst", uri.normalize("/endel%C3%B8st"))
+    it("does not decode non-ASCII characters that are unreserved, issue #2366", function()
+      assert.equal("/endel%C3%B8st", uri.normalize("/endel%C3%B8st"))
+    end)
+
+    it("does normalize complex uri that has characters outside of normal uri charset", function()
+      assert.equal("/%C3%A4/a./a/_%99%AF%2F%2F" , uri.normalize("/ä/a/%2e./a%2E//a/%2e/./a/../a/%2e%2E/%5f%99%af%2f%2F", true))
     end)
   end)
 
@@ -66,4 +70,10 @@ describe("kong.tools.uri", function()
       assert.equal("/endel%C3%B8st", uri.escape("/endeløst"))
     end)
   end)
+
+  describe("unescape()", function()
+    it("decodes non-ASCII characters that are unreserved, issue #2366", function()
+      assert.equal("/endeløst", uri.unescape("/endel%C3%B8st"))
+    end)
+  end)
 end)