feat: disable http2 traffic when using ai-proxy plugin

kong/init.lua

@@ -1032,6 +1032,8 @@ function Kong.ssl_certificate()
   kong.table.clear(ngx.ctx)
 end
 
+function Kong.ssl_client_hello()
+end
 
 function Kong.preread()
   local ctx = get_ctx_table(fetch_table(CTX_NS, CTX_NARR, CTX_NREC))

kong/llm/proxy/handler.lua

@@ -13,7 +13,14 @@ local kong_utils = require("kong.tools.gzip")
 local buffer = require "string.buffer"
 local strip = require("kong.tools.string").strip
 local cycle_aware_deep_copy = require("kong.tools.table").cycle_aware_deep_copy
+local kong_global = require("kong.global")
+local PHASES = kong_global.phases
 
+local certificate = require("kong.tls.plugins.certificate")
+local sni_filter = require("kong.tls.plugins.sni_filter")
+
+local TTL_FOREVER = { ttl = 0 }
+-- local SNI_CACHE_KEY = "ai:llm:cert_enabled_snis"
 
 local EMPTY = require("kong.tools.table").EMPTY
 
@@ -477,4 +484,31 @@ function _M:access(conf)
 
 end
 
+function _M:init_worker_for_plugin(plugin_name)
+  -- TODO: remove nasty hacks once we have singleton phases support in core
+
+  local orig_ssl_client_hello = kong.ssl_client_hello   -- luacheck: ignore
+  kong.ssl_client_hello = function()                   -- luacheck: ignore
+    orig_ssl_client_hello()
+
+    local ctx = ngx.ctx
+    -- ensure phases are set
+    ctx.KONG_PHASE = PHASES.certificate
+
+    kong_global.set_namespaced_log(kong, plugin_name)
+    local sni_cache_key = "ai:llm:cert_enabled_snis:" .. plugin_name
+    local snis_set, err = kong.cache:get(sni_cache_key, TTL_FOREVER,
+    sni_filter.build_ssl_route_filter_set, plugin_name)
+
+    if err then
+      kong.log.err("unable to request client to present its certificate: ",
+            err)
+      return ngx.exit(ngx.ERROR)
+    end
+    certificate.execute_client_hello(snis_set, { disable_http2 = true })
+    kong_global.reset_log(kong)
+
+  end
+end
+
 return _M

kong/plugins/ai-proxy/handler.lua

@@ -3,7 +3,9 @@ local deep_copy = require "kong.tools.table".deep_copy
 
 
 local _M = deep_copy(require("kong.llm.proxy.handler"))
-
+_M.init_worker = function()
+    _M.init_worker_for_plugin("ai-proxy")
+end
 
 _M.PRIORITY = 770
 _M.VERSION = kong_meta.version

kong/templates/nginx_kong.lua

@@ -126,6 +126,9 @@ server {
     ssl_certificate_by_lua_block {
         Kong.ssl_certificate()
     }
+    ssl_client_hello_by_lua_block {
+        Kong.ssl_client_hello()
+    }
 > end
 
     # injected nginx_proxy_* directives

kong/templates/nginx_kong_stream.lua

@@ -119,6 +119,9 @@ server {
     ssl_certificate_by_lua_block {
         Kong.ssl_certificate()
     }
+    ssl_client_hello_by_lua_block {
+        Kong.ssl_client_hello()
+    }
 > end
 
     set $upstream_host '';

kong/tls/plugins/certificate.lua

@@ -7,6 +7,7 @@
 
 --- Copyright 2019 Kong Inc.
 local ngx_ssl = require "ngx.ssl"
+local ssl_clt = require "ngx.ssl.clienthello"
 local sni_filter = require("kong.tls.plugins.sni_filter")
 local pl_stringx = require "pl.stringx"
 local server_name = ngx_ssl.server_name
@@ -22,7 +23,6 @@ local EMPTY_T = {}
 
 
 local function match_sni(snis, server_name)
-  local matched_sni
   if server_name then
     -- search plain snis
     if snis[server_name] then
@@ -96,4 +96,35 @@ function _M.execute(snis_set)
   end
 end
 
+function _M.execute_client_hello(snis_set, options)
+
+  if not options then
+    return
+  end
+
+  if not options.disable_http2 then
+    return
+  end
+
+  local server_name, err = ssl_clt.get_client_hello_server_name()
+  if err then
+    kong.log.debug("unable to get client hello server name: ", err)
+    return
+  end
+
+  local sni_mapping = match_sni(snis_set, server_name)
+
+  if sni_mapping  then
+    -- TODO: improve detection of ennoblement once we have DAO functions
+    -- to filter plugin configurations based on plugin name
+
+    kong.log.debug("enabled, will disable http2 alpn")
+
+    local res, err = kong.tls.disable_http2_alpn()
+    if not res then
+      kong.log.err("unable to disable http2 alpn: ", err)
+    end
+  end
+end
+
 return _M

spec/fixtures/1.2_custom_nginx.template

@@ -102,6 +102,9 @@ http {
         ssl_certificate_by_lua_block {
             Kong.ssl_certificate()
         }
+        ssl_client_hello_by_lua_block {
+            Kong.ssl_client_hello()
+        }
 > end
 
         # injected nginx_proxy_* directives