[nginx] Rewrite: disallow empty replacements.

[Ruslan Ermilov]

details:   https://hg.nginx.org/nginx/rev/db8df9cd84c8
branches:  
changeset: 7606:db8df9cd84c8
user:      Ruslan Ermilov <ru at nginx.com>
date:      Mon Dec 16 15:19:01 2019 +0300
description:
Rewrite: disallow empty replacements.

While empty replacements were caught at run-time, parsing code
of the "rewrite" directive expects that a minimum length of the
"replacement" argument is 1.

diffstat:

 src/http/modules/ngx_http_rewrite_module.c |  5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diffs (15 lines):

diff -r 02a539522be4 -r db8df9cd84c8 src/http/modules/ngx_http_rewrite_module.c
--- a/src/http/modules/ngx_http_rewrite_module.c	Mon Dec 16 15:19:01 2019 +0300
+++ b/src/http/modules/ngx_http_rewrite_module.c	Mon Dec 16 15:19:01 2019 +0300
@@ -318,6 +318,11 @@
 
     value = cf->args->elts;
 
+    if (value[2].len == 0) {
+        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "empty replacement");
+        return NGX_CONF_ERROR;
+    }
+
     ngx_memzero(&rc, sizeof(ngx_regex_compile_t));
 
     rc.pattern = value[1];