Python: Added "prefix" to configuration.

This patch gives users the option to set a `"prefix"` attribute
for Python applications, either at the top level or for specific
`"target"`s. If the attribute is present, the value of `"prefix"`
must be a string beginning with `"/"`. If the value of the `"prefix"`
attribute is longer than 1 character and ends in `"/"`, the
trailing `"/"` is stripped.

The purpose of the `"prefix"` attribute is to set the `SCRIPT_NAME`
context value for WSGI applications and the `root_path` context
value for ASGI applications, allowing applications to properly route
requests regardless of the path that the server uses to expose the
application.

The context value is only set if the request's URL path begins with
the value of the `"prefix"` attribute. In all other cases, the
`SCRIPT_NAME` or `root_path` values are not set. In addition, for
WSGI applications, the value of `"prefix"` will be stripped from
the beginning of the request's URL path before it is sent to the
application.

Reviewed-by: Andrei Zeliankou <zelenkov@nginx.com>
Reviewed-by: Artem Konev <artem.konev@nginx.com>
Signed-off-by: Alejandro Colomar <alx@nginx.com>

1 files changed, 36 insertions, 13 deletions

diff --git a/src/python/nxt_python_wsgi.c b/src/python/nxt_python_wsgi.c
index 34afd9a9..dfb31509 100644
--- a/src/python/nxt_python_wsgi.c
+++ b/src/python/nxt_python_wsgi.c
@@ -60,7 +60,8 @@ static void nxt_python_request_handler(nxt_unit_request_info_t *req);
 
 static PyObject *nxt_python_create_environ(nxt_python_app_conf_t *c);
 static PyObject *nxt_python_copy_environ(nxt_unit_request_info_t *req);
-static PyObject *nxt_python_get_environ(nxt_python_ctx_t *pctx);
+static PyObject *nxt_python_get_environ(nxt_python_ctx_t *pctx,
+    nxt_python_target_t *app_target);
 static int nxt_python_add_sptr(nxt_python_ctx_t *pctx, PyObject *name,
     nxt_unit_sptr_t *sptr, uint32_t size);
 static int nxt_python_add_char(nxt_python_ctx_t *pctx, PyObject *name,
@@ -141,6 +142,7 @@ static PyObject  *nxt_py_query_string_str;
 static PyObject  *nxt_py_remote_addr_str;
 static PyObject  *nxt_py_request_method_str;
 static PyObject  *nxt_py_request_uri_str;
+static PyObject  *nxt_py_script_name_str;
 static PyObject  *nxt_py_server_addr_str;
 static PyObject  *nxt_py_server_name_str;
 static PyObject  *nxt_py_server_port_str;
@@ -160,6 +162,7 @@ static nxt_python_string_t nxt_python_strings[] = {
     { nxt_string("REMOTE_ADDR"), &nxt_py_remote_addr_str },
     { nxt_string("REQUEST_METHOD"), &nxt_py_request_method_str },
     { nxt_string("REQUEST_URI"), &nxt_py_request_uri_str },
+    { nxt_string("SCRIPT_NAME"), &nxt_py_script_name_str },
     { nxt_string("SERVER_ADDR"), &nxt_py_server_addr_str },
     { nxt_string("SERVER_NAME"), &nxt_py_server_name_str },
     { nxt_string("SERVER_PORT"), &nxt_py_server_port_str },
@@ -304,11 +307,12 @@ nxt_python_wsgi_done(void)
 static void
 nxt_python_request_handler(nxt_unit_request_info_t *req)
 {
-    int               rc;
-    PyObject          *environ, *args, *response, *iterator, *item;
-    PyObject          *close, *result, *application;
-    nxt_bool_t        prepare_environ;
-    nxt_python_ctx_t  *pctx;
+    int                  rc;
+    PyObject             *environ, *args, *response, *iterator, *item;
+    PyObject             *close, *result;
+    nxt_bool_t           prepare_environ;
+    nxt_python_ctx_t     *pctx;
+    nxt_python_target_t  *target;
 
     pctx = req->ctx->data;
 
@@ -331,7 +335,9 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
 
     prepare_environ = 1;
 
-    environ = nxt_python_get_environ(pctx);
+    target = &nxt_py_targets->target[req->request->app_target];
+
+    environ = nxt_python_get_environ(pctx, target);
     if (nxt_slow_path(environ == NULL)) {
         rc = NXT_UNIT_ERROR;
         goto done;
@@ -352,8 +358,7 @@ nxt_python_request_handler(nxt_unit_request_info_t *req)
     Py_INCREF(pctx->start_resp);
     PyTuple_SET_ITEM(args, 1, pctx->start_resp);
 
-    application = nxt_py_targets->target[req->request->app_target].application;
-    response = PyObject_CallObject(application, args);
+    response = PyObject_CallObject(target->application, args);
 
     Py_DECREF(args);
 
@@ -584,11 +589,14 @@ nxt_python_copy_environ(nxt_unit_request_info_t *req)
 
 
 static PyObject *
-nxt_python_get_environ(nxt_python_ctx_t *pctx)
+nxt_python_get_environ(nxt_python_ctx_t *pctx,
+    nxt_python_target_t *app_target)
 {
     int                 rc;
-    uint32_t            i, j, vl;
+    char                *path;
+    uint32_t            i, j, vl, path_length;
     PyObject            *environ;
+    nxt_str_t           prefix;
     nxt_unit_field_t    *f, *f2;
     nxt_unit_request_t  *r;
 
@@ -608,8 +616,23 @@ nxt_python_get_environ(nxt_python_ctx_t *pctx)
                            r->target_length));
     RC(nxt_python_add_sptr(pctx, nxt_py_query_string_str, &r->query,
                            r->query_length));
-    RC(nxt_python_add_sptr(pctx, nxt_py_path_info_str, &r->path,
-                           r->path_length));
+
+    prefix = app_target->prefix;
+    path_length = r->path_length;
+    path = nxt_unit_sptr_get(&r->path);
+    if (prefix.length > 0
+        && ((path_length > prefix.length && path[prefix.length] == '/')
+            || path_length == prefix.length)
+        && memcmp(prefix.start, path, prefix.length) == 0)
+    {
+        RC(nxt_python_add_py_string(pctx, nxt_py_script_name_str,
+                                    app_target->py_prefix));
+
+        path += prefix.length;
+        path_length -= prefix.length;
+    }
+
+    RC(nxt_python_add_char(pctx, nxt_py_path_info_str, path, path_length));
 
     RC(nxt_python_add_sptr(pctx, nxt_py_remote_addr_str, &r->remote,
                            r->remote_length));