Check onion keys in microdescriptors, too

changes/bug3207

@@ -0,0 +1,4 @@
+  o Minor bugfixes:
+    - Require that onion keys have exponent 65537 in microdescriptors too.
+      Fixes part of bug 3207; bugfix on 0.2.2.25-alpha
+

src/or/routerparse.c

@@ -4336,6 +4336,11 @@ microdescs_parse_from_string(const char *s, const char *eos,
     }
 
     tok = find_by_keyword(tokens, K_ONION_KEY);
+    if (!crypto_pk_check_key_public_exponent(tok->key)) {
+      log_warn(LD_DIR,
+               "Relay's onion key had invalid exponent.");
+      goto next;
+    }
     md->onion_pkey = tok->key;
     tok->key = NULL;