The ASAN build fails with
```
cookie_auth.c:62:7: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
  if (cookie_header == NULL) goto clean;
      ^~~~~~~~~~~~~~~~~~~~~
cookie_auth.c:84:10: note: uninitialized use occurs here
  return ret;
         ^~~
cookie_auth.c:62:3: note: remove the 'if' if its condition is always false
  if (cookie_header == NULL) goto clean;
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cookie_auth.c:65:3: note: variable 'ret' is declared here
  struct session *ret = NULL;
  ^
cookie_auth.c:62:7: error: variable 'ssid' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
  if (cookie_header == NULL) goto clean;
      ^~~~~~~~~~~~~~~~~~~~~
cookie_auth.c:81:7: note: uninitialized use occurs here
  if (ssid != ssid_buf) {
      ^~~~
cookie_auth.c:62:3: note: remove the 'if' if its condition is always false
  if (cookie_header == NULL) goto clean;
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cookie_auth.c:64:3: note: variable 'ssid' is declared here
  char *ssid = ssid_buf;
  ^
2 errors generated.
```