Added support for "429 Too Many Requests" response (RFC6585).

This change adds reason phrase in status line and pretty response body
when "429" status code is used in "return", "limit_conn_status" and/or
"limit_req_status" directives.

Signed-off-by: Piotr Sikora <piotrsikora@google.com>

src/http/ngx_http_header_filter_module.c

diff --git a/src/http/ngx_http_header_filter_module.c b/src/http/ngx_http_header_filter_module.c
index ddae613..c09c519 100644
--- a/src/http/ngx_http_header_filter_module.c
+++ b/src/http/ngx_http_header_filter_module.c
@@ -101,12 +101,16 @@
     ngx_null_string,  /* "419 unused" */
     ngx_null_string,  /* "420 unused" */
     ngx_string("421 Misdirected Request"),
+    ngx_null_string,  /* "422 Unprocessable Entity" */
+    ngx_null_string,  /* "423 Locked" */
+    ngx_null_string,  /* "424 Failed Dependency" */
+    ngx_null_string,  /* "425 unused" */
+    ngx_null_string,  /* "426 Upgrade Required" */
+    ngx_null_string,  /* "427 unused" */
+    ngx_null_string,  /* "428 Precondition Required" */
+    ngx_string("429 Too Many Requests"),
 
-    /* ngx_null_string, */  /* "422 Unprocessable Entity" */
-    /* ngx_null_string, */  /* "423 Locked" */
-    /* ngx_null_string, */  /* "424 Failed Dependency" */
-
-#define NGX_HTTP_LAST_4XX  422
+#define NGX_HTTP_LAST_4XX  430
 #define NGX_HTTP_OFF_5XX   (NGX_HTTP_LAST_4XX - 400 + NGX_HTTP_OFF_4XX)
 
     ngx_string("500 Internal Server Error"),

src/http/ngx_http_request.h

diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
index 780a99f..a68b906 100644
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -98,6 +98,7 @@
 #define NGX_HTTP_UNSUPPORTED_MEDIA_TYPE    415
 #define NGX_HTTP_RANGE_NOT_SATISFIABLE     416
 #define NGX_HTTP_MISDIRECTED_REQUEST       421
+#define NGX_HTTP_TOO_MANY_REQUESTS         429
 
 
 /* Our own HTTP codes */

src/http/ngx_http_special_response.c

diff --git a/src/http/ngx_http_special_response.c b/src/http/ngx_http_special_response.c
index 9de0d15..c9b1017 100644
--- a/src/http/ngx_http_special_response.c
+++ b/src/http/ngx_http_special_response.c
@@ -225,6 +225,14 @@
 ;
 
 
+static char ngx_http_error_429_page[] =
+"<html>" CRLF
+"<head><title>429 Too Many Requests</title></head>" CRLF
+"<body bgcolor=\"white\">" CRLF
+"<center><h1>429 Too Many Requests</h1></center>" CRLF
+;
+
+
 static char ngx_http_error_494_page[] =
 "<html>" CRLF
 "<head><title>400 Request Header Or Cookie Too Large</title></head>"
@@ -354,8 +362,16 @@
     ngx_null_string,                     /* 419 */
     ngx_null_string,                     /* 420 */
     ngx_string(ngx_http_error_421_page),
+    ngx_null_string,                     /* 422 */
+    ngx_null_string,                     /* 423 */
+    ngx_null_string,                     /* 424 */
+    ngx_null_string,                     /* 425 */
+    ngx_null_string,                     /* 426 */
+    ngx_null_string,                     /* 427 */
+    ngx_null_string,                     /* 428 */
+    ngx_string(ngx_http_error_429_page),
 
-#define NGX_HTTP_LAST_4XX  422
+#define NGX_HTTP_LAST_4XX  430
 #define NGX_HTTP_OFF_5XX   (NGX_HTTP_LAST_4XX - 400 + NGX_HTTP_OFF_4XX)
 
     ngx_string(ngx_http_error_494_page), /* 494, request header too large */