use ngx_strnstr()

src/http/modules/ngx_http_flv_module.c

diff --git a/src/http/modules/ngx_http_flv_module.c b/src/http/modules/ngx_http_flv_module.c
index 04327d9..3de4ebf 100644
--- a/src/http/modules/ngx_http_flv_module.c
+++ b/src/http/modules/ngx_http_flv_module.c
@@ -166,7 +166,7 @@
     i = 1;
 
     if (r->args.len) {
-        p = (u_char *) ngx_strstr(r->args.data, "start=");
+        p = (u_char *) ngx_strnstr(r->args.data, "start=", r->args.len);
 
         if (p) {
             p += 6;