Python: supporting ASGI legacy protocol.

Introducing manual protocol selection for 'universal' apps and frameworks.

7 files changed, 184 insertions, 27 deletions

diff --git a/src/nxt_application.h b/src/nxt_application.h
index 66c0e1f7..5632f56f 100644
--- a/src/nxt_application.h
+++ b/src/nxt_application.h
@@ -51,6 +51,7 @@ typedef struct {
     nxt_str_t  path;
     nxt_str_t  module;
     char       *callable;
+    nxt_str_t  protocol;
     uint32_t   threads;
     uint32_t   thread_stack_size;
 } nxt_python_app_conf_t;
diff --git a/src/nxt_conf_validation.c b/src/nxt_conf_validation.c
index 8e6279fa..fc521016 100644
--- a/src/nxt_conf_validation.c
+++ b/src/nxt_conf_validation.c
@@ -95,6 +95,8 @@ static nxt_int_t nxt_conf_vldt_return(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
 static nxt_int_t nxt_conf_vldt_proxy(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
+static nxt_int_t nxt_conf_vldt_python_protocol(nxt_conf_validation_t *vldt,
+    nxt_conf_value_t *value, void *data);
 static nxt_int_t nxt_conf_vldt_threads(nxt_conf_validation_t *vldt,
     nxt_conf_value_t *value, void *data);
 static nxt_int_t nxt_conf_vldt_thread_stack_size(nxt_conf_validation_t *vldt,
@@ -494,6 +496,10 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_python_members[] = {
         .name       = nxt_string("callable"),
         .type       = NXT_CONF_VLDT_STRING,
     }, {
+        .name       = nxt_string("protocol"),
+        .type       = NXT_CONF_VLDT_STRING,
+        .validator  = nxt_conf_vldt_python_protocol,
+    }, {
         .name       = nxt_string("threads"),
         .type       = NXT_CONF_VLDT_INTEGER,
         .validator  = nxt_conf_vldt_threads,
@@ -1361,6 +1367,26 @@ nxt_conf_vldt_proxy(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
 
 
 static nxt_int_t
+nxt_conf_vldt_python_protocol(nxt_conf_validation_t *vldt,
+    nxt_conf_value_t *value, void *data)
+{
+    nxt_str_t  proto;
+
+    static const nxt_str_t  wsgi = nxt_string("wsgi");
+    static const nxt_str_t  asgi = nxt_string("asgi");
+
+    nxt_conf_get_string(value, &proto);
+
+    if (nxt_strstr_eq(&proto, &wsgi) || nxt_strstr_eq(&proto, &asgi)) {
+        return NXT_OK;
+    }
+
+    return nxt_conf_vldt_error(vldt, "The \"protocol\" can either be "
+                                     "\"wsgi\" or \"asgi\".");
+}
+
+
+static nxt_int_t
 nxt_conf_vldt_threads(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
     void *data)
 {
diff --git a/src/nxt_main_process.c b/src/nxt_main_process.c
index 99fc7995..0cde435b 100644
--- a/src/nxt_main_process.c
+++ b/src/nxt_main_process.c
@@ -199,6 +199,12 @@ static nxt_conf_map_t  nxt_python_app_conf[] = {
     },
 
     {
+        nxt_string("protocol"),
+        NXT_CONF_MAP_STR,
+        offsetof(nxt_common_app_conf_t, u.python.protocol),
+    },
+
+    {
         nxt_string("threads"),
         NXT_CONF_MAP_INT32,
         offsetof(nxt_common_app_conf_t, u.python.threads),
diff --git a/src/python/nxt_python.c b/src/python/nxt_python.c
index 26a6f093..faf0c0e1 100644
--- a/src/python/nxt_python.c
+++ b/src/python/nxt_python.c
@@ -68,6 +68,7 @@ nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
     char                   *nxt_py_module;
     size_t                 len;
     PyObject               *obj, *pypath, *module;
+    nxt_str_t              proto;
     const char             *callable;
     nxt_unit_ctx_t         *unit_ctx;
     nxt_unit_init_t        python_init;
@@ -82,6 +83,9 @@ nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
     static const char bin_python[] = "/bin/python";
 #endif
 
+    static const nxt_str_t  wsgi = nxt_string("wsgi");
+    static const nxt_str_t  asgi = nxt_string("asgi");
+
     app_conf = data->app;
     c = &app_conf->u.python;
 
@@ -244,7 +248,13 @@ nxt_python_start(nxt_task_t *task, nxt_process_data_t *data)
     python_init.shm_limit = data->app->shm_limit;
     python_init.callbacks.ready_handler = nxt_python_ready_handler;
 
-    if (nxt_python_asgi_check(nxt_py_application)) {
+    proto = c->protocol;
+
+    if (proto.length == 0) {
+        proto = nxt_python_asgi_check(nxt_py_application) ? asgi : wsgi;
+    }
+
+    if (nxt_strstr_eq(&proto, &asgi)) {
         rc = nxt_python_asgi_init(&python_init, &nxt_py_proto);
 
     } else {
diff --git a/src/python/nxt_python_asgi.c b/src/python/nxt_python_asgi.c
index cab73239..e11a3b6c 100644
--- a/src/python/nxt_python_asgi.c
+++ b/src/python/nxt_python_asgi.c
@@ -16,6 +16,7 @@
 #include <python/nxt_python_asgi_str.h>
 
 
+static PyObject *nxt_python_asgi_get_func(PyObject *obj);
 static int nxt_python_asgi_ctx_data_alloc(void **pdata);
 static void nxt_python_asgi_ctx_data_free(void *data);
 static int nxt_python_asgi_startup(void *data);
@@ -42,6 +43,7 @@ static PyObject *nxt_py_asgi_port_read(PyObject *self, PyObject *args);
 static void nxt_python_asgi_done(void);
 
 
+int                       nxt_py_asgi_legacy;
 static PyObject           *nxt_py_port_read;
 static nxt_unit_port_t    *nxt_py_shared_port;
 
@@ -64,56 +66,78 @@ int
 nxt_python_asgi_check(PyObject *obj)
 {
     int           res;
-    PyObject      *call;
+    PyObject      *func;
     PyCodeObject  *code;
 
-    if (PyFunction_Check(obj)) {
-        code = (PyCodeObject *) PyFunction_GET_CODE(obj);
+    func = nxt_python_asgi_get_func(obj);
+
+    if (func == NULL) {
+        return 0;
+    }
+
+    code = (PyCodeObject *) PyFunction_GET_CODE(func);
+
+    nxt_unit_debug(NULL, "asgi_check: callable is %sa coroutine function with "
+                         "%d argument(s)",
+                   (code->co_flags & CO_COROUTINE) != 0 ? "" : "not ",
+                   code->co_argcount);
+
+    res = (code->co_flags & CO_COROUTINE) != 0 || code->co_argcount == 1;
+
+    Py_DECREF(func);
+
+    return res;
+}
+
+
+static PyObject *
+nxt_python_asgi_get_func(PyObject *obj)
+{
+    PyObject  *call;
 
-        return (code->co_flags & CO_COROUTINE) != 0;
+    if (PyFunction_Check(obj)) {
+        Py_INCREF(obj);
+        return obj;
     }
 
     if (PyMethod_Check(obj)) {
         obj = PyMethod_GET_FUNCTION(obj);
 
-        code = (PyCodeObject *) PyFunction_GET_CODE(obj);
-
-        return (code->co_flags & CO_COROUTINE) != 0;
+        Py_INCREF(obj);
+        return obj;
     }
 
     call = PyObject_GetAttrString(obj, "__call__");
 
     if (call == NULL) {
-        return 0;
+        return NULL;
     }
 
     if (PyFunction_Check(call)) {
-        code = (PyCodeObject *) PyFunction_GET_CODE(call);
-
-        res = (code->co_flags & CO_COROUTINE) != 0;
-
-    } else {
-        if (PyMethod_Check(call)) {
-            obj = PyMethod_GET_FUNCTION(call);
+        return call;
+    }
 
-            code = (PyCodeObject *) PyFunction_GET_CODE(obj);
+    if (PyMethod_Check(call)) {
+        obj = PyMethod_GET_FUNCTION(call);
 
-            res = (code->co_flags & CO_COROUTINE) != 0;
+        Py_INCREF(obj);
+        Py_DECREF(call);
 
-        } else {
-            res = 0;
-        }
+        return obj;
     }
 
     Py_DECREF(call);
 
-    return res;
+    return NULL;
 }
 
 
 int
 nxt_python_asgi_init(nxt_unit_init_t *init, nxt_python_proto_t *proto)
 {
+    PyObject      *func;
+    PyCodeObject  *code;
+
     nxt_unit_debug(NULL, "asgi_init");
 
     if (nxt_slow_path(nxt_py_asgi_str_init() != NXT_UNIT_OK)) {
@@ -136,6 +160,22 @@ nxt_python_asgi_init(nxt_unit_init_t *init, nxt_python_proto_t *proto)
         return NXT_UNIT_ERROR;
     }
 
+    func = nxt_python_asgi_get_func(nxt_py_application);
+    if (nxt_slow_path(func == NULL)) {
+        nxt_unit_alert(NULL, "Python cannot find function for callable");
+        return NXT_UNIT_ERROR;
+    }
+
+    code = (PyCodeObject *) PyFunction_GET_CODE(func);
+
+    if ((code->co_flags & CO_COROUTINE) == 0) {
+        nxt_unit_debug(NULL, "asgi: callable is not a coroutine function "
+                             "switching to legacy mode");
+        nxt_py_asgi_legacy = 1;
+    }
+
+    Py_DECREF(func);
+
     init->callbacks.request_handler = nxt_py_asgi_request_handler;
     init->callbacks.data_handler = nxt_py_asgi_http_data_handler;
     init->callbacks.websocket_handler = nxt_py_asgi_websocket_handler;
@@ -366,6 +406,7 @@ static void
 nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
 {
     PyObject                *scope, *res, *task, *receive, *send, *done, *asgi;
+    PyObject                *stage2;
     nxt_py_asgi_ctx_data_t  *ctx_data;
 
     if (req->request->websocket_handshake) {
@@ -415,8 +456,42 @@ nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
 
     req->data = asgi;
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_application,
-                                       scope, receive, send, NULL);
+    if (!nxt_py_asgi_legacy) {
+        nxt_unit_req_debug(req, "Python call ASGI 3.0 application");
+
+        res = PyObject_CallFunctionObjArgs(nxt_py_application,
+                                           scope, receive, send, NULL);
+
+    } else {
+        nxt_unit_req_debug(req, "Python call legacy application");
+
+        res = PyObject_CallFunctionObjArgs(nxt_py_application, scope, NULL);
+
+        if (nxt_slow_path(res == NULL)) {
+            nxt_unit_req_error(req, "Python failed to call legacy app stage1");
+            nxt_python_print_exception();
+            nxt_unit_request_done(req, NXT_UNIT_ERROR);
+
+            goto release_scope;
+        }
+
+        if (nxt_slow_path(PyCallable_Check(res) == 0)) {
+            nxt_unit_req_error(req,
+                              "Legacy ASGI application returns not a callable");
+            nxt_unit_request_done(req, NXT_UNIT_ERROR);
+
+            Py_DECREF(res);
+
+            goto release_scope;
+        }
+
+        stage2 = res;
+
+        res = PyObject_CallFunctionObjArgs(stage2, receive, send, NULL);
+
+        Py_DECREF(stage2);
+    }
+
     if (nxt_slow_path(res == NULL)) {
         nxt_unit_req_error(req, "Python failed to call the application");
         nxt_python_print_exception();
diff --git a/src/python/nxt_python_asgi.h b/src/python/nxt_python_asgi.h
index 69d58477..c3c3e17a 100644
--- a/src/python/nxt_python_asgi.h
+++ b/src/python/nxt_python_asgi.h
@@ -68,4 +68,6 @@ int nxt_py_asgi_lifespan_startup(nxt_py_asgi_ctx_data_t *ctx_data);
 int nxt_py_asgi_lifespan_shutdown(nxt_unit_ctx_t *ctx);
 
 
+extern int  nxt_py_asgi_legacy;
+
 #endif  /* _NXT_PYTHON_ASGI_H_INCLUDED_ */
diff --git a/src/python/nxt_python_asgi_lifespan.c b/src/python/nxt_python_asgi_lifespan.c
index 6910d2e8..506eaf4d 100644
--- a/src/python/nxt_python_asgi_lifespan.c
+++ b/src/python/nxt_python_asgi_lifespan.c
@@ -71,6 +71,7 @@ nxt_py_asgi_lifespan_startup(nxt_py_asgi_ctx_data_t *ctx_data)
 {
     int                     rc;
     PyObject                *scope, *res, *py_task, *receive, *send, *done;
+    PyObject                *stage2;
     nxt_py_asgi_lifespan_t  *lifespan;
 
     if (nxt_slow_path(PyType_Ready(&nxt_py_asgi_lifespan_type) != 0)) {
@@ -129,8 +130,43 @@ nxt_py_asgi_lifespan_startup(nxt_py_asgi_ctx_data_t *ctx_data)
         goto release_future;
     }
 
-    res = PyObject_CallFunctionObjArgs(nxt_py_application,
-                                       scope, receive, send, NULL);
+    if (!nxt_py_asgi_legacy) {
+        nxt_unit_req_debug(NULL, "Python call ASGI 3.0 application");
+
+        res = PyObject_CallFunctionObjArgs(nxt_py_application,
+                                           scope, receive, send, NULL);
+
+    } else {
+        nxt_unit_req_debug(NULL, "Python call legacy application");
+
+        res = PyObject_CallFunctionObjArgs(nxt_py_application, scope, NULL);
+        if (nxt_slow_path(res == NULL)) {
+            nxt_unit_log(NULL, NXT_UNIT_LOG_INFO,
+                         "ASGI Lifespan processing exception");
+            nxt_python_print_exception();
+
+            lifespan->disabled = 1;
+            rc = NXT_UNIT_OK;
+
+            goto release_scope;
+        }
+
+        if (nxt_slow_path(PyCallable_Check(res) == 0)) {
+            nxt_unit_req_error(NULL,
+                              "Legacy ASGI application returns not a callable");
+
+            Py_DECREF(res);
+
+            goto release_scope;
+        }
+
+        stage2 = res;
+
+        res = PyObject_CallFunctionObjArgs(stage2, receive, send, NULL);
+
+        Py_DECREF(stage2);
+    }
+
     if (nxt_slow_path(res == NULL)) {
         nxt_unit_error(NULL, "Python failed to call the application");
         nxt_python_print_exception();
@@ -143,7 +179,8 @@ nxt_py_asgi_lifespan_startup(nxt_py_asgi_ctx_data_t *ctx_data)
         goto release_scope;
     }
 
-    py_task = PyObject_CallFunctionObjArgs(ctx_data->loop_create_task, res, NULL);
+    py_task = PyObject_CallFunctionObjArgs(ctx_data->loop_create_task, res,
+                                           NULL);
     if (nxt_slow_path(py_task == NULL)) {
         nxt_unit_alert(NULL, "Python failed to call the create_task");
         nxt_python_print_exception();