Added pass_subrequest_uri option

Previous implementation unconditionally passes unparsed uri, recieved
from client. However it can be changed due to several internal
redirects, such as rewrite, X-Accel-Redirect, etc. If the new option for
tnt_pass_http_request is set, the actual subrequest uri will be passed
to tarantool upstream.

Default behaviour coincides with the old one for saving backward
compatibility.

Author: igormunkin

README.md

@@ -512,7 +512,7 @@ Example:
 
 tnt_pass_http_request
 ---------------------
-**syntax:** *tnt_pass_http_request [on|off|parse_args|unescape|pass_body|pass_headers_out|parse_urlencoded]*
+**syntax:** *tnt_pass_http_request [on|off|parse_args|unescape|pass_body|pass_headers_out|parse_urlencoded|pass_subrequest_uri]*
 
 **default:** *off*
 
@@ -599,6 +599,49 @@ Examples #3 (parse_urlencoded):
   end
 ```
 
+Examples #4 (pass_subrequest_uri):
+
+* Origin (unparsed) uri
+```nginx
+  location /web {
+    # Backend processing /web/foo and replying with X-Accel-Redirect to
+    # internal /tnt/bar
+    proxy_pass http://x-accel-redirect-backend;
+  }
+  location /tnt {
+    internal;
+    tnt_pass_http_request on;
+    tnt_method tarantool_xar_handler;
+    tnt_pass 127.0.0.1:9999;
+  }
+```
+```lua
+  function tarantool_xar_handler(req, ...)
+    print(req.uri) -- /web/foo
+    return true
+  end
+```
+* Subrequest uri
+```nginx
+  location /web {
+    # Backend processing /web/foo and replying with X-Accel-Redirect to
+    # internal /tnt/bar
+    proxy_pass http://x-accel-redirect-backend;
+  }
+  location /tnt {
+    internal;
+    tnt_pass_http_request on pass_subrequest_uri;
+    tnt_method tarantool_xar_handler;
+    tnt_pass 127.0.0.1:9999;
+  }
+```
+```lua
+  function tarantool_xar_handler(req, ...)
+    print(req.uri) -- /tnt/bar
+    return true
+  end
+```
+
 ```bash
   # Call tarantool_stored_procedure_name()
   $> wget NGINX_HOST/tarantool_stored_procedure_name/some/mega/path?q=1&q=2&q=3

src/ngx_http_tnt_module.c

@@ -43,13 +43,14 @@
 
 
 typedef enum ngx_tnt_conf_states {
-    NGX_TNT_CONF_ON               = 1,
-    NGX_TNT_CONF_OFF              = 2,
-    NGX_TNT_CONF_PARSE_ARGS       = 4,
-    NGX_TNT_CONF_UNESCAPE         = 8,
-    NGX_TNT_CONF_PASS_BODY        = 16,
-    NGX_TNT_CONF_PASS_HEADERS_OUT = 32,
-    NGX_TNT_CONF_PARSE_URLENCODED = 64,
+    NGX_TNT_CONF_ON                  = 1,
+    NGX_TNT_CONF_OFF                 = 2,
+    NGX_TNT_CONF_PARSE_ARGS          = 4,
+    NGX_TNT_CONF_UNESCAPE            = 8,
+    NGX_TNT_CONF_PASS_BODY           = 16,
+    NGX_TNT_CONF_PASS_HEADERS_OUT    = 32,
+    NGX_TNT_CONF_PARSE_URLENCODED    = 64,
+    NGX_TNT_CONF_PASS_SUBREQUEST_URI = 128,
 } ngx_tnt_conf_states_e;
 
 
@@ -427,6 +428,7 @@ static ngx_conf_bitmask_t  ngx_http_tnt_pass_http_request_masks[] = {
     { ngx_string("pass_body"), NGX_TNT_CONF_PASS_BODY },
     { ngx_string("pass_headers_out"), NGX_TNT_CONF_PASS_HEADERS_OUT },
     { ngx_string("parse_urlencoded"), NGX_TNT_CONF_PARSE_URLENCODED },
+    { ngx_string("pass_subrequest_uri"), NGX_TNT_CONF_PASS_SUBREQUEST_URI },
     { ngx_null_string, 0 }
 };
 
@@ -3166,13 +3168,18 @@ ngx_http_tnt_get_request_data(ngx_http_request_t *r,
         goto oom_cant_encode;
     }
 
-    /** Encode raw uri */
+    /** Encode uri:
+     *      whether NGX_TNT_CONF_PASS_SUBREQUEST_URI is not set then raw uri
+     *      will be chosen, otherwise preprocessed value will be used
+     */
     ++root_items;
 
+    ngx_str_t uri = tlcf->pass_http_request & NGX_TNT_CONF_PASS_SUBREQUEST_URI
+        ? r->uri : r->unparsed_uri;
+
     if (ngx_http_tnt_encode_str_map_item(r, tlcf, tp,
                                          (u_char *) "uri", sizeof("uri") - 1,
-                                         r->unparsed_uri.data,
-                                         r->unparsed_uri.len) == NGX_ERROR)
+                                         uri.data, uri.len) == NGX_ERROR)
     {
         goto oom_cant_encode;
     }

src/ngx_http_tnt_version.h

@@ -34,6 +34,6 @@
 #ifndef NGX_HTTP_TNT_VERSION_H
 #define NGX_HTTP_TNT_VERSION_H 1
 
-#define NGX_HTTP_TNT_MODULE_VERSION_STRING "v2.5-rc4"
+#define NGX_HTTP_TNT_MODULE_VERSION_STRING "v2.7"
 
 #endif