Move rend auth cookie en-/decoding to a function

Tor stores client authorization cookies in two slightly different forms.
The service's client_keys file has the standard base64-encoded cookie,
including two chars of padding. The hostname file and the client remove
the two padding chars, and store an auth type flag in the unused bits.

The distinction makes no sense. Refactor all decoding to use the same
function, which will accept either form, and use a helper function for
encoding the truncated format.

1 files changed, 6 insertions, 16 deletions

diff --git a/src/or/routerparse.c b/src/or/routerparse.c
index c2206f1075..35f76cdc3e 100644
--- a/src/or/routerparse.c
+++ b/src/or/routerparse.c
@@ -5290,6 +5290,7 @@ rend_parse_client_keys(strmap_t *parsed_clients, const char *ckstr)
   directory_token_t *tok;
   const char *current_entry = NULL;
   memarea_t *area = NULL;
+  char *err_msg = NULL;
   if (!ckstr || strlen(ckstr) == 0)
     return -1;
   tokens = smartlist_new();
@@ -5300,7 +5301,6 @@ rend_parse_client_keys(strmap_t *parsed_clients, const char *ckstr)
   while (!strcmpstart(current_entry, "client-name ")) {
     rend_authorized_client_t *parsed_entry;
     size_t len;
-    char descriptor_cookie_tmp[REND_DESC_COOKIE_LEN+2];
     /* Determine end of string. */
     const char *eos = strstr(current_entry, "\nclient-name ");
     if (!eos)
@@ -5356,23 +5356,13 @@ rend_parse_client_keys(strmap_t *parsed_clients, const char *ckstr)
     /* Parse descriptor cookie. */
     tok = find_by_keyword(tokens, C_DESCRIPTOR_COOKIE);
     tor_assert(tok->n_args == 1);
-    if (strlen(tok->args[0]) != REND_DESC_COOKIE_LEN_BASE64 + 2) {
-      log_warn(LD_REND, "Descriptor cookie has illegal length: %s",
-               escaped(tok->args[0]));
-      goto err;
-    }
-    /* The size of descriptor_cookie_tmp needs to be REND_DESC_COOKIE_LEN+2,
-     * because a base64 encoding of length 24 does not fit into 16 bytes in all
-     * cases. */
-    if (base64_decode(descriptor_cookie_tmp, sizeof(descriptor_cookie_tmp),
-                      tok->args[0], strlen(tok->args[0]))
-        != REND_DESC_COOKIE_LEN) {
-      log_warn(LD_REND, "Descriptor cookie contains illegal characters: "
-               "%s", escaped(tok->args[0]));
+    if (rend_auth_decode_cookie(tok->args[0], parsed_entry->descriptor_cookie,
+                                NULL, &err_msg) < 0) {
+      tor_assert(err_msg);
+      log_warn(LD_REND, "%s", err_msg);
+      tor_free(err_msg);
       goto err;
     }
-    memcpy(parsed_entry->descriptor_cookie, descriptor_cookie_tmp,
-           REND_DESC_COOKIE_LEN);
   }
   result = strmap_size(parsed_clients);
   goto done;