allow short secure links

src/http/modules/ngx_http_secure_link_module.c

diff --git a/src/http/modules/ngx_http_secure_link_module.c b/src/http/modules/ngx_http_secure_link_module.c
index 0b2a445..049a45c 100644
--- a/src/http/modules/ngx_http_secure_link_module.c
+++ b/src/http/modules/ngx_http_secure_link_module.c
@@ -113,7 +113,7 @@
 
     len = last - p;
 
-    if (end - start != 32 || len < 3) {
+    if (end - start != 32 || len == 0) {
         goto not_found;
     }