chore(ai-prompt-decorator): improve error handling and cleanup (#12907)

* chore(ai-prompt-decorator): improve error handling and cleanup

* chore(test): standard test filenames

* chore(ai-prompt-guard): improve error handling and cleanup

changelog/unreleased/kong/cleanup_ai.yml

@@ -0,0 +1,4 @@
+message: |
+  Cleanup some AI plugins, and improve errorhandling.
+type: bugfix
+scope: Plugin

kong/plugins/ai-prompt-decorator/handler.lua

@@ -1,28 +1,29 @@
-local _M = {}
-
--- imports
-local kong_meta    = require "kong.meta"
-local new_tab      = require("table.new")
+local new_tab = require("table.new")
 local EMPTY = {}
---
 
-_M.PRIORITY = 772
-_M.VERSION = kong_meta.version
+
+local plugin = {
+  PRIORITY = 772,
+  VERSION = require("kong.meta").version
+}
+
 
 
 local function bad_request(msg)
   kong.log.debug(msg)
   return kong.response.exit(400, { error = { message = msg } })
 end
 
-function _M.execute(request, conf)
+
+
+-- Adds the prompts to the request prepend/append.
+-- @tparam table request The deserialized JSON body of the request
+-- @tparam table conf The plugin configuration
+-- @treturn table The decorated request (same table, content updated)
+local function execute(request, conf)
   local prepend = conf.prompts.prepend or EMPTY
   local append = conf.prompts.append or EMPTY
 
-  if #prepend == 0 and #append == 0 then
-    return request, nil
-  end
-
   local old_messages = request.messages
   local new_messages = new_tab(#append + #prepend + #old_messages, 0)
   request.messages = new_messages
@@ -44,29 +45,34 @@ function _M.execute(request, conf)
     new_messages[n] = { role = msg.role, content = msg.content }
   end
 
-  return request, nil
+  return request
 end
 
-function _M:access(conf)
+
+
+function plugin:access(conf)
   kong.service.request.enable_buffering()
   kong.ctx.shared.ai_prompt_decorated = true  -- future use
 
   -- if plugin ordering was altered, receive the "decorated" request
-  local request, err = kong.request.get_body("application/json")
-  if err then
+  local request = kong.request.get_body("application/json")
+  if type(request) ~= "table"  then
     return bad_request("this LLM route only supports application/json requests")
   end
 
-  if not request.messages or #request.messages < 1 then
+  if #(request.messages or EMPTY) < 1 then
     return bad_request("this LLM route only supports llm/chat type requests")
   end
 
-  local decorated_request, err = self.execute(request, conf)
-  if err then
-    return bad_request(err)
-  end
-
-  kong.service.request.set_body(decorated_request, "application/json")
+  kong.service.request.set_body(execute(request, conf), "application/json")
 end
 
-return _M
+
+
+if _G._TEST then
+  -- only if we're testing export this function (using a different name!)
+  plugin._execute = execute
+end
+
+
+return plugin

kong/plugins/ai-prompt-guard/handler.lua

@@ -1,112 +1,145 @@
-local _M = {}
-
--- imports
-local kong_meta   = require "kong.meta"
-local buffer      = require("string.buffer")
+local buffer = require("string.buffer")
 local ngx_re_find = ngx.re.find
---
+local EMPTY = {}
 
-_M.PRIORITY = 771
-_M.VERSION = kong_meta.version
 
-local function bad_request(msg, reveal_msg_to_client)
-  -- don't let users know 'ai-prompt-guard' is in use
-  kong.log.info(msg)
-  if not reveal_msg_to_client then
-    msg = "bad request"
-  end
+
+local plugin = {
+  PRIORITY = 771,
+  VERSION = require("kong.meta").version
+}
+
+
+
+local function bad_request(msg)
+  kong.log.debug(msg)
   return kong.response.exit(400, { error = { message = msg } })
 end
 
-function _M.execute(request, conf)
-  local user_prompt
 
-  -- concat all 'user' prompts into one string, if conversation history must be checked
-  if request.messages and not conf.allow_all_conversation_history then
-    local buf = buffer.new()
 
-    for _, v in ipairs(request.messages) do
-      if v.role == "user" then
-        buf:put(v.content)
+local execute do
+  local bad_format_error = "ai-prompt-guard only supports llm/v1/chat or llm/v1/completions prompts"
+
+  -- Checks the prompt for the given patterns.
+  -- _Note_: if a regex fails, it returns a 500, and exits the request.
+  -- @tparam table request The deserialized JSON body of the request
+  -- @tparam table conf The plugin configuration
+  -- @treturn[1] table The decorated request (same table, content updated)
+  -- @treturn[2] nil
+  -- @treturn[2] string The error message
+  function execute(request, conf)
+    local user_prompt
+
+    -- concat all 'user' prompts into one string, if conversation history must be checked
+    if type(request.messages) == "table" and not conf.allow_all_conversation_history then
+      local buf = buffer.new()
+
+      for _, v in ipairs(request.messages) do
+        if type(v.role) ~= "string" then
+          return nil, bad_format_error
+        end
+        if v.role == "user" then
+          if type(v.content) ~= "string" then
+            return nil, bad_format_error
+          end
+          buf:put(v.content)
+        end
       end
-    end
 
-    user_prompt = buf:get()
-
-  elseif request.messages then
-    -- just take the trailing 'user' prompt
-    for _, v in ipairs(request.messages) do
-      if v.role == "user" then
-        user_prompt = v.content
+      user_prompt = buf:get()
+
+    elseif type(request.messages) == "table" then
+      -- just take the trailing 'user' prompt
+      for _, v in ipairs(request.messages) do
+        if type(v.role) ~= "string" then
+          return nil, bad_format_error
+        end
+        if v.role == "user" then
+          if type(v.content) ~= "string" then
+            return nil, bad_format_error
+          end
+          user_prompt = v.content
+        end
       end
-    end
 
-  elseif request.prompt then
-    user_prompt = request.prompt
+    elseif type(request.prompt) == "string" then
+      user_prompt = request.prompt
 
-  else
-    return nil, "ai-prompt-guard only supports llm/v1/chat or llm/v1/completions prompts"
-  end
+    else
+      return nil, bad_format_error
+    end
+
+    if not user_prompt then
+      return nil, "no 'prompt' or 'messages' received"
+    end
 
-  if not user_prompt then
-    return nil, "no 'prompt' or 'messages' received"
-  end
 
-  -- check the prompt for explcit ban patterns
-  if conf.deny_patterns and #conf.deny_patterns > 0 then
-    for _, v in ipairs(conf.deny_patterns) do
+    -- check the prompt for explcit ban patterns
+    for _, v in ipairs(conf.deny_patterns or EMPTY) do
       -- check each denylist; if prompt matches it, deny immediately
       local m, _, err = ngx_re_find(user_prompt, v, "jo")
       if err then
-        return nil, "bad regex execution for: " .. v
+        -- regex failed, that's an error by the administrator
+        kong.log.err("bad regex pattern '", v ,"', failed to execute: ", err)
+        return kong.response.exit(500)
 
       elseif m then
         return nil, "prompt pattern is blocked"
       end
     end
-  end
 
-  -- if any allow_patterns specified, make sure the prompt matches one of them
-  if conf.allow_patterns and #conf.allow_patterns > 0 then
-    local valid = false
 
-    for _, v in ipairs(conf.allow_patterns) do
+    if #(conf.allow_patterns or EMPTY) == 0 then
+      -- no allow_patterns, so we're good
+      return true
+    end
+
+    -- if any allow_patterns specified, make sure the prompt matches one of them
+    for _, v in ipairs(conf.allow_patterns or EMPTY) do
       -- check each denylist; if prompt matches it, deny immediately
       local m, _, err = ngx_re_find(user_prompt, v, "jo")
 
       if err then
-        return nil, "bad regex execution for: " .. v
+        -- regex failed, that's an error by the administrator
+        kong.log.err("bad regex pattern '", v ,"', failed to execute: ", err)
+        return kong.response.exit(500)
 
       elseif m then
-        valid = true
-        break
+        return true  -- got a match so is allowed, exit early
       end
     end
 
-    if not valid then
-      return false, "prompt doesn't match any allowed pattern"
-    end
+    return false, "prompt doesn't match any allowed pattern"
   end
-
-  return true, nil
 end
 
-function _M:access(conf)
+
+
+function plugin:access(conf)
   kong.service.request.enable_buffering()
   kong.ctx.shared.ai_prompt_guarded = true -- future use
 
   -- if plugin ordering was altered, receive the "decorated" request
-  local request, err = kong.request.get_body("application/json")
-
-  if err then
-    return bad_request("this LLM route only supports application/json requests", true)
+  local request = kong.request.get_body("application/json")
+  if type(request) ~= "table" then
+    return bad_request("this LLM route only supports application/json requests")
   end
 
   -- run access handler
-  local ok, err = self.execute(request, conf)
+  local ok, err = execute(request, conf)
   if not ok then
-    return bad_request(err, false)
+    kong.log.debug(err)
+    return bad_request("bad request") -- don't let users know 'ai-prompt-guard' is in use
   end
 end
 
-return _M
+
+
+if _G._TEST then
+  -- only if we're testing export this function (using a different name!)
+  plugin._execute = execute
+end
+
+
+return plugin

kong/plugins/ai-prompt-guard/schema.lua

@@ -8,19 +8,19 @@ return {
       type = "record",
       fields = {
           { allow_patterns = {
-              description = "Array of valid patterns, or valid questions from the 'user' role in chat.",
+              description = "Array of valid regex patterns, or valid questions from the 'user' role in chat.",
               type = "array",
-              default = {},
+              required = false,
               len_max = 10,
               elements = {
                 type = "string",
                 len_min = 1,
                 len_max = 500,
               }}},
           { deny_patterns = {
-              description = "Array of invalid patterns, or invalid questions from the 'user' role in chat.",
+              description = "Array of invalid regex patterns, or invalid questions from the 'user' role in chat.",
               type = "array",
-              default = {},
+              required = false,
               len_max = 10,
               elements = {
                 type = "string",