[wip] feat(proxy-wasm) host-managed property getters and setters using the Lua bridge

lib/resty/wasmx.lua

@@ -15,10 +15,14 @@ ffi.cdef [[
         ngx_str_t       *config;
     } ngx_wasm_filter_t;
 
+    typedef intptr_t                      ngx_int_t;
     typedef unsigned char                 u_char;
     typedef struct ngx_wavm_t             ngx_wasm_vm_t;
     typedef struct ngx_wasm_ops_plan_t    ngx_wasm_plan_t;
 
+    typedef ngx_int_t (*ngx_wasm_host_prop_fn_t)(void *data, ngx_str_t *key,
+        ngx_str_t *value);
+
     ngx_wasm_vm_t *ngx_wasm_ffi_main_vm();
 ]]
 

lib/resty/wasmx/proxy_wasm.lua

@@ -38,23 +38,25 @@ local _M = {
 
 if subsystem == "http" then
     ffi.cdef [[
-        int ngx_http_wasm_ffi_plan_new(ngx_wasm_vm_t *vm,
-                                       ngx_wasm_filter_t *filters,
-                                       size_t n_filters,
-                                       ngx_wasm_plan_t **out,
-                                       u_char *err, size_t *errlen);
-        int ngx_http_wasm_ffi_plan_free(ngx_wasm_plan_t *plan);
-        int ngx_http_wasm_ffi_plan_load(ngx_wasm_plan_t *plan);
-        int ngx_http_wasm_ffi_plan_attach(ngx_http_request_t *r,
-                                          ngx_wasm_plan_t *plan,
-                                          unsigned int isolation);
-        int ngx_http_wasm_ffi_start(ngx_http_request_t *r);
-        int ngx_http_wasm_ffi_set_property(ngx_http_request_t *r,
-                                           ngx_str_t *key,
-                                           ngx_str_t *value);
-        int ngx_http_wasm_ffi_get_property(ngx_http_request_t *r,
-                                           ngx_str_t *key,
-                                           ngx_str_t *out);
+        ngx_int_t ngx_http_wasm_ffi_plan_new(ngx_wasm_vm_t *vm,
+                                             ngx_wasm_filter_t *filters,
+                                             size_t n_filters,
+                                             ngx_wasm_plan_t **out,
+                                             u_char *err, size_t *errlen);
+        ngx_int_t ngx_http_wasm_ffi_plan_free(ngx_wasm_plan_t *plan);
+        ngx_int_t ngx_http_wasm_ffi_plan_load(ngx_wasm_plan_t *plan);
+        ngx_int_t ngx_http_wasm_ffi_plan_attach(ngx_http_request_t *r,
+                                                ngx_wasm_plan_t *plan,
+                                                unsigned int isolation);
+        ngx_int_t ngx_http_wasm_ffi_start(ngx_http_request_t *r);
+        ngx_int_t ngx_http_wasm_ffi_set_property(ngx_http_request_t *r,
+                                                 ngx_str_t *key,
+                                                 ngx_str_t *value);
+        ngx_int_t ngx_http_wasm_ffi_get_property(ngx_http_request_t *r,
+                                                 ngx_str_t *key,
+                                                 ngx_str_t *out);
+        ngx_int_t ngx_http_wasm_ffi_enable_property_setter(ngx_http_request_t *r);
+        ngx_int_t ngx_http_wasm_ffi_enable_property_getter(ngx_http_request_t *r);
     ]]
 
 else
@@ -229,7 +231,7 @@ function _M.set_property(key, value)
         error("key must be a string", 2)
     end
 
-    if type(value) ~= "string" then
+    if value ~= nil and type(value) ~= "string" then
         error("value must be a string", 2)
     end
 
@@ -238,8 +240,14 @@ function _M.set_property(key, value)
         error("no request found", 2)
     end
 
-    local ckey = ffi_new("ngx_str_t", { data = key, len = #key })
-    local cvalue = ffi_new("ngx_str_t", { data = value, len = #value })
+    local ckey = ffi_new("ngx_str_t", {
+        data = key,
+        len = #key
+    })
+    local cvalue = ffi_new("ngx_str_t", {
+        data = value,
+        len = value and #value or 0
+    })
 
     local rc = C.ngx_http_wasm_ffi_set_property(r, ckey, cvalue)
     if rc == FFI_ERROR then
@@ -276,8 +284,81 @@ function _M.get_property(key)
         return nil, "property \"" .. key .. "\" not found", NOT_FOUND
     end
 
+    if cvalue.data == nil then
+        return nil
+    end
+
     return ffi_str(cvalue.data, cvalue.len)
 end
 
 
+---
+-- Define a setter function for host-managed properties.
+--
+-- @param setter The setter function is the handler for updating properties.
+-- Its type signature is `function(string, string): boolean, string`,
+-- where the inputs are the property key and value and the results are:
+-- * `truthy` - success setting the property
+-- * `truthy, value` - success, cache property value (useful if hosts
+--   sets only a setter but not a getter)
+-- * `truthy, value, truthy` - success, constant property value: further
+--   requests to the same property during a request are cached by
+--   ngx_wasm_module and do not invoke the Lua getter.
+-- * `falsy, err` - failure, and an optional error message
+-- @return true on success setting the getter, or nil and an error message.
+function _M.set_property_setter(setter)
+    if type(setter) ~= "function" then
+        error("setter must be a function", 2)
+    end
+
+    local r = get_request()
+    if not r then
+        error("no request found", 2)
+    end
+
+    _M.property_setter = setter
+
+    local rc = C.ngx_http_wasm_ffi_enable_property_setter(r)
+    if rc ~= FFI_OK then
+        return nil, "could not set property setter"
+    end
+
+    return true
+end
+
+
+---
+-- Define a getter function for host-managed properties.
+--
+-- @param getter The getter function is the handler for resolving properties.
+-- Its type signature is `function(string): boolean, string, boolean`,
+-- where the input is the property key and the results are:
+-- * `truthy, value` - success, property value
+-- * `truthy, value, truthy` - success, constant property value: further
+--   requests to the same property during a request are cached by
+--   ngx_wasm_module and do not invoke the Lua getter.
+-- * `falsy` - property not found
+-- * `falsy, err` - failure, error message
+-- @return true on success setting the getter, or nil and an error message.
+function _M.set_property_getter(getter)
+    if type(getter) ~= "function" then
+        error("getter must be a function", 2)
+    end
+
+    local r = get_request()
+    if not r then
+        error("no request found", 2)
+    end
+
+    _M.property_getter = getter
+
+    local rc = C.ngx_http_wasm_ffi_enable_property_getter(r)
+    if rc ~= FFI_OK then
+        return nil, "could not set property getter"
+    end
+
+    return true
+end
+
+
 return _M

src/common/lua/ngx_wasm_lua.c

@@ -1,5 +1,5 @@
 #ifndef DDEBUG
-#define DDEBUG 0
+#define DDEBUG 1
 #endif
 #include "ddebug.h"
 
@@ -113,6 +113,56 @@ ngx_wasm_lua_thread_destroy(ngx_wasm_lua_ctx_t *lctx)
 }
 
 
+static ngx_int_t
+ngx_wasm_lua_load_code(ngx_wasm_lua_ctx_t *lctx,
+    const char *tag, const char *src,
+    ngx_wasm_subsys_env_t *env)
+{
+    ngx_int_t  rc;
+
+    lctx->code = src;
+    lctx->code_len = ngx_strlen(src);
+    lctx->cache_key = ngx_wasm_lua_thread_cache_key(lctx->pool,
+                                                    tag,
+                                                    (u_char *) lctx->code,
+                                                    lctx->code_len);
+    if (lctx->cache_key == NULL) {
+        return NGX_ERROR;
+    }
+
+    /* load code */
+
+    switch (env->subsys->kind) {
+#if (NGX_WASM_HTTP)
+    case NGX_WASM_SUBSYS_HTTP:
+        rc = ngx_http_lua_cache_loadbuffer(lctx->log,
+                                           lctx->L,
+                                           (u_char *) lctx->code,
+                                           lctx->code_len,
+                                           &lctx->code_ref,
+                                           lctx->cache_key,
+                                           tag);
+        break;
+#endif
+#if (NGX_WASM_STREAM)
+    case NGX_WASM_SUBSYS_STREAM:
+        rc = ngx_stream_lua_cache_loadbuffer(lctx->log,
+                                             lctx->L,
+                                             (u_char *) lctx->code,
+                                             lctx->code_len,
+                                             lctx->cache_key,
+                                             tag);
+        break;
+#endif
+    default:
+        ngx_wasm_assert(0);
+        return NGX_ERROR;
+    }
+
+    return rc;
+}
+
+
 ngx_wasm_lua_ctx_t *
 ngx_wasm_lua_thread_new(const char *tag, const char *src,
     ngx_wasm_subsys_env_t *env, ngx_log_t *log, void *data,
@@ -155,6 +205,9 @@ ngx_wasm_lua_thread_new(const char *tag, const char *src,
 
         lctx->L = ngx_http_lua_get_lua_vm(r, NULL);
         lctx->co = ngx_http_lua_new_thread(r, lctx->L, &lctx->co_ref);
+
+        ngx_http_lua_set_req(lctx->co, r);
+
         break;
     }
 #endif
@@ -166,6 +219,9 @@ ngx_wasm_lua_thread_new(const char *tag, const char *src,
 
         lctx->L = ngx_stream_lua_get_lua_vm(sr, NULL);
         lctx->co = ngx_stream_lua_new_thread(sr, lctx->L, lctx->co_ref);
+
+        ngx_stream_lua_set_req(lctx->co, sr);
+
         break;
     }
 #endif
@@ -183,47 +239,11 @@ ngx_wasm_lua_thread_new(const char *tag, const char *src,
 
     /* code */
 
-    lctx->code = src;
-    lctx->code_len = ngx_strlen(src);
-    lctx->cache_key = ngx_wasm_lua_thread_cache_key(lctx->pool,
-                                                    tag,
-                                                    (u_char *) lctx->code,
-                                                    lctx->code_len);
-    if (lctx->cache_key == NULL) {
-        goto error;
-    }
-
-    /* load code */
-
-    switch (env->subsys->kind) {
-#if (NGX_WASM_HTTP)
-    case NGX_WASM_SUBSYS_HTTP:
-        rc = ngx_http_lua_cache_loadbuffer(lctx->log,
-                                           lctx->L,
-                                           (u_char *) lctx->code,
-                                           lctx->code_len,
-                                           &lctx->code_ref,
-                                           lctx->cache_key,
-                                           tag);
-        break;
-#endif
-#if (NGX_WASM_STREAM)
-    case NGX_WASM_SUBSYS_STREAM:
-        rc = ngx_stream_lua_cache_loadbuffer(lctx->log,
-                                             lctx->L,
-                                             (u_char *) lctx->code,
-                                             lctx->code_len,
-                                             lctx->cache_key,
-                                             tag);
-        break;
-#endif
-    default:
-        ngx_wasm_assert(0);
-        goto error;
-    }
-
-    if (rc != NGX_OK) {
-        goto error;
+    if (src) {
+        rc = ngx_wasm_lua_load_code(lctx, tag, src, env);
+        if (rc != NGX_OK) {
+            goto error;
+        }
     }
 
     /*  move code closure to new coroutine  */