Fix the position-check for ed25519 certs to work with annotations

When there are annotations on a router descriptor, the
ed25519-identity element won't be at position 0 or 1; it will be at
router+1 or router-1.

This patch also adds a missing smartlist function to search a list for
an item with a particular pointer.

src/common/container.c

@@ -208,6 +208,19 @@ smartlist_string_pos(const smartlist_t *sl, const char *element)
   return -1;
 }
 
+/** If <b>element</b> is the same pointer as an element of <b>sl</b>, return
+ * that element's index.  Otherwise, return -1. */
+int
+smartlist_pos(const smartlist_t *sl, const void *element)
+{
+  int i;
+  if (!sl) return -1;
+  for (i=0; i < sl->num_used; i++)
+    if (element == sl->list[i])
+      return i;
+  return -1;
+}
+
 /** Return true iff <b>sl</b> has some element E such that
  * !strcasecmp(E,<b>element</b>)
  */

src/common/container.h

@@ -38,6 +38,7 @@ void smartlist_reverse(smartlist_t *sl);
 void smartlist_string_remove(smartlist_t *sl, const char *element);
 int smartlist_contains(const smartlist_t *sl, const void *element);
 int smartlist_contains_string(const smartlist_t *sl, const char *element);
+int smartlist_pos(const smartlist_t *sl, const void *element);
 int smartlist_string_pos(const smartlist_t *, const char *elt);
 int smartlist_contains_string_case(const smartlist_t *sl, const char *element);
 int smartlist_contains_int_as_string(const smartlist_t *sl, int num);

src/or/routerparse.c

@@ -1195,6 +1195,7 @@ router_parse_entry_from_string(const char *s, const char *end,
   }
 
   tok = find_by_keyword(tokens, K_ROUTER);
+  const int router_token_pos = smartlist_pos(tokens, tok);
   tor_assert(tok->n_args >= 5);
 
   router = tor_malloc_zero(sizeof(routerinfo_t));
@@ -1345,8 +1346,10 @@ router_parse_entry_from_string(const char *s, const char *end,
     }
     if (ed_sig_tok) {
       tor_assert(ed_cert_tok && cc_tap_tok && cc_ntor_tok);
-      if (ed_cert_tok != smartlist_get(tokens, 0) &&
-          ed_cert_tok != smartlist_get(tokens, 1)) {
+      const int ed_cert_token_pos = smartlist_pos(tokens, ed_cert_tok);
+      if (ed_cert_token_pos == -1 || router_token_pos == -1 ||
+          (ed_cert_token_pos != router_token_pos + 1 &&
+           ed_cert_token_pos != router_token_pos - 1)) {
         log_warn(LD_DIR, "Ed25519 certificate in wrong position");
         goto err;
       }

src/test/test_containers.c

@@ -495,6 +495,43 @@ test_container_smartlist_join(void *arg)
   tor_free(joined);
 }
 
+static void
+test_container_smartlist_pos(void *arg)
+{
+  (void) arg;
+  smartlist_t *sl = smartlist_new();
+
+  smartlist_add(sl, tor_strdup("This"));
+  smartlist_add(sl, tor_strdup("is"));
+  smartlist_add(sl, tor_strdup("a"));
+  smartlist_add(sl, tor_strdup("test"));
+  smartlist_add(sl, tor_strdup("for"));
+  smartlist_add(sl, tor_strdup("a"));
+  smartlist_add(sl, tor_strdup("function"));
+
+  /* Test string_pos */
+  tt_int_op(smartlist_string_pos(NULL, "Fred"), ==, -1);
+  tt_int_op(smartlist_string_pos(sl, "Fred"), ==, -1);
+  tt_int_op(smartlist_string_pos(sl, "This"), ==, 0);
+  tt_int_op(smartlist_string_pos(sl, "a"), ==, 2);
+  tt_int_op(smartlist_string_pos(sl, "function"), ==, 6);
+
+  /* Test pos */
+  tt_int_op(smartlist_pos(NULL, "Fred"), ==, -1);
+  tt_int_op(smartlist_pos(sl, "Fred"), ==, -1);
+  tt_int_op(smartlist_pos(sl, "This"), ==, -1);
+  tt_int_op(smartlist_pos(sl, "a"), ==, -1);
+  tt_int_op(smartlist_pos(sl, "function"), ==, -1);
+  tt_int_op(smartlist_pos(sl, smartlist_get(sl,0)), ==, 0);
+  tt_int_op(smartlist_pos(sl, smartlist_get(sl,2)), ==, 2);
+  tt_int_op(smartlist_pos(sl, smartlist_get(sl,5)), ==, 5);
+  tt_int_op(smartlist_pos(sl, smartlist_get(sl,6)), ==, 6);
+
+ done:
+  SMARTLIST_FOREACH(sl, char *, cp, tor_free(cp));
+  smartlist_free(sl);
+}
+
 static void
 test_container_smartlist_ints_eq(void *arg)
 {
@@ -1053,6 +1090,7 @@ struct testcase_t container_tests[] = {
   CONTAINER_LEGACY(smartlist_overlap),
   CONTAINER_LEGACY(smartlist_digests),
   CONTAINER_LEGACY(smartlist_join),
+  CONTAINER_LEGACY(smartlist_pos),
   CONTAINER(smartlist_ints_eq, 0),
   CONTAINER_LEGACY(bitarray),
   CONTAINER_LEGACY(digestset),