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, 21 insertions, 7 deletions

diff --git a/src/python/nxt_python_asgi.c b/src/python/nxt_python_asgi.c
index 256bcdcc..587a17cf 100644
--- a/src/python/nxt_python_asgi.c
+++ b/src/python/nxt_python_asgi.c
@@ -27,7 +27,8 @@ static void nxt_py_asgi_remove_reader(nxt_unit_ctx_t *ctx,
 static void nxt_py_asgi_request_handler(nxt_unit_request_info_t *req);
 static void nxt_py_asgi_close_handler(nxt_unit_request_info_t *req);
 
-static PyObject *nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req);
+static PyObject *nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req,
+    nxt_python_target_t *app_target);
 static PyObject *nxt_py_asgi_create_address(nxt_unit_sptr_t *sptr, uint8_t len,
     uint16_t port);
 static PyObject *nxt_py_asgi_create_ip_address(nxt_unit_sptr_t *sptr,
@@ -455,16 +456,16 @@ nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
         goto release_send;
     }
 
-    scope = nxt_py_asgi_create_http_scope(req);
+    req->data = asgi;
+    target = &nxt_py_targets->target[req->request->app_target];
+
+    scope = nxt_py_asgi_create_http_scope(req, target);
     if (nxt_slow_path(scope == NULL)) {
         nxt_unit_request_done(req, NXT_UNIT_ERROR);
 
         goto release_done;
     }
 
-    req->data = asgi;
-    target = &nxt_py_targets->target[req->request->app_target];
-
     if (!target->asgi_legacy) {
         nxt_unit_req_debug(req, "Python call ASGI 3.0 application");
 
@@ -573,12 +574,14 @@ nxt_py_asgi_close_handler(nxt_unit_request_info_t *req)
 
 
 static PyObject *
-nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req)
+nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req,
+    nxt_python_target_t *app_target)
 {
     char                *p, *target, *query;
-    uint32_t            target_length, i;
+    uint32_t            target_length, i, path_length;
     PyObject            *scope, *v, *type, *scheme;
     PyObject            *headers, *header;
+    nxt_str_t           prefix;
     nxt_unit_field_t    *f;
     nxt_unit_request_t  *r;
 
@@ -612,6 +615,17 @@ nxt_py_asgi_create_http_scope(nxt_unit_request_info_t *req)
         return NULL;
     }
 
+    prefix = app_target->prefix;
+    path_length = r->path_length;
+    p = nxt_unit_sptr_get(&r->path);
+    if (prefix.length > 0
+        && ((path_length > prefix.length && p[prefix.length] == '/')
+            || path_length == prefix.length)
+        && memcmp(prefix.start, p, prefix.length) == 0)
+    {
+        SET_ITEM(scope, root_path, app_target->py_prefix);
+    }
+
     p = nxt_unit_sptr_get(&r->version);
     SET_ITEM(scope, http_version, p[7] == '1' ? nxt_py_1_1_str
                                               : nxt_py_1_0_str)