fix(core): validation against header regex match

Fixup #12365
Fix KAG-4788

Co-authored-by: Qi <[email protected]>

kong/db/schema/entities/routes.lua

@@ -196,10 +196,7 @@ local routes = {
             },
           },
         },
-        values = {
-          type = "array",
-          elements = typedefs.regex_or_plain_pattern,
-        }
+        values = typedefs.header_regex_or_plain_pattern,
       } },
 
       { regex_priority = { description = "A number used to choose which route resolves a given request when several routes match it using regexes simultaneously.", type = "integer", default = 0 }, },

kong/db/schema/typedefs.lua

@@ -504,14 +504,13 @@ end
 
 
 local function is_valid_regex_pattern(pattern)
-  local regex = pattern:sub(2) -- remove the leading "~"
   -- the value will be interpreted as a regex by the router; but is it a
   -- valid one? Let's dry-run it with the same options as our router.
-  local _, _, err = ngx.re.find("", regex, "aj")
+  local _, _, err = ngx.re.find("", pattern, "a")
   if err then
     return nil,
            string.format("invalid regex: '%s' (PCRE returned: %s)",
-                         regex, err)
+                         pattern, err)
   end
 
   return true
@@ -526,7 +525,7 @@ local function validate_path_with_regexes(path)
   end
 
   if is_regex_pattern(path) then
-    return is_valid_regex_pattern(path)
+    return is_valid_regex_pattern(path:sub(2))
   end
 
   -- prefix matching. let's check if it's normalized form
@@ -539,12 +538,13 @@ local function validate_path_with_regexes(path)
 end
 
 
-local function validate_regex_or_plain_pattern(pattern)
-  if not is_regex_pattern(pattern) then
+local function validate_header_regex_or_plain_pattern(patterns)
+  -- when there's only 1 pattern and it starts with "~*", it's a regex pattern
+  if #patterns ~= 1 or patterns[1]:sub(1, 2) ~= "~*" then
     return true
   end
 
-  return is_valid_regex_pattern(pattern)
+  return is_valid_regex_pattern(patterns[1]:sub(3))
 end
 
 
@@ -646,9 +646,12 @@ typedefs.headers = Schema.define {
   description = "A map of header names to arrays of header values."
 }
 
-typedefs.regex_or_plain_pattern = Schema.define {
-  type = "string",
-  custom_validator = validate_regex_or_plain_pattern,
+typedefs.header_regex_or_plain_pattern = Schema.define {
+  type = "array",
+  elements = {
+    type = "string",
+  },
+  custom_validator = validate_header_regex_or_plain_pattern,
   description = "A string representing a regex or plain pattern."
 }
 

spec/01-unit/01-db/01-schema/06-routes_spec.lua

@@ -624,14 +624,25 @@ describe("routes schema (flavor = " .. flavor .. ")", function()
 
     it("value must be a plain pattern or a valid regex pattern", function()
       local route = {
-        headers = { location = { "~[" } },
+        headers = { location = { "~*[" } },
         protocols = { "http" },
       }
 
       local ok, err = Routes:validate(route)
       assert.falsy(ok)
       assert.match("invalid regex", err.headers[1])
     end)
+
+    it("value must be a plain pattern or a valid regex pattern", function()
+      local route = {
+        headers = { location = { "~*[", "~*" } },
+        protocols = { "http" },
+      }
+
+      local ok, err = Routes:validate(route)
+      assert.truthy(ok)
+      assert.match(nil, err)
+    end)
   end)
 
   describe("methods attribute", function()