Implement option to turn off DNS cache modification by a client port

(This is part 3 of making DNS cache use enabled/disabled on a
per-client port basis.  This implements the UseCacheIPv[46]DNS options)

src/or/addressmap.c

@@ -594,13 +594,13 @@ client_dns_clear_failures(const char *address)
  * <b>ttl</b>seconds; otherwise, we use the default.
  */
 static void
-client_dns_set_addressmap_impl(origin_circuit_t *on_circ,
+client_dns_set_addressmap_impl(entry_connection_t *for_conn,
                                const char *address, const char *name,
                                const char *exitname,
                                int ttl)
 {
   char *extendedaddress=NULL, *extendedval=NULL;
-  (void)on_circ;
+  (void)for_conn;
 
   tor_assert(address);
   tor_assert(name);
@@ -640,7 +640,7 @@ client_dns_set_addressmap_impl(origin_circuit_t *on_circ,
  * <b>ttl</b>seconds; otherwise, we use the default.
  */
 void
-client_dns_set_addressmap(origin_circuit_t *on_circ,
+client_dns_set_addressmap(entry_connection_t *for_conn,
                           const char *address,
                           const tor_addr_t *val,
                           const char *exitname,
@@ -655,14 +655,18 @@ client_dns_set_addressmap(origin_circuit_t *on_circ,
   if (tor_addr_parse(&addr_tmp, address) >= 0)
     return; /* If address was an IP address already, don't add a mapping. */
 
-  /* XXXXX For now, don't cache IPv6 addresses. */
-  if (tor_addr_family(val) != AF_INET)
-    return;
+  if (tor_addr_family(val) == AF_INET) {
+    if (! for_conn->cache_ipv4_answers)
+      return;
+  } else if (tor_addr_family(val) == AF_INET6) {
+    if (! for_conn->cache_ipv6_answers)
+      return;
+  }
 
   if (! tor_addr_to_str(valbuf, val, sizeof(valbuf), 1))
     return;
 
-  client_dns_set_addressmap_impl(on_circ, address, valbuf, exitname, ttl);
+  client_dns_set_addressmap_impl(for_conn, address, valbuf, exitname, ttl);
 }
 
 /** Add a cache entry noting that <b>address</b> (ordinarily a dotted quad)
@@ -675,14 +679,21 @@ client_dns_set_addressmap(origin_circuit_t *on_circ,
  * <b>ttl</b>seconds; otherwise, we use the default.
  */
 void
-client_dns_set_reverse_addressmap(origin_circuit_t *on_circ,
+client_dns_set_reverse_addressmap(entry_connection_t *for_conn,
                                   const char *address, const char *v,
                                   const char *exitname,
                                   int ttl)
 {
   char *s = NULL;
+  {
+    tor_addr_t tmp_addr;
+    sa_family_t f = tor_addr_parse(&tmp_addr, address);
+    if ((f == AF_INET && ! for_conn->cache_ipv4_answers) ||
+        (f == AF_INET6 && ! for_conn->cache_ipv6_answers))
+      return;
+  }
   tor_asprintf(&s, "REVERSE[%s]", address);
-  client_dns_set_addressmap_impl(on_circ, s, v, exitname, ttl);
+  client_dns_set_addressmap_impl(for_conn, s, v, exitname, ttl);
   tor_free(s);
 }
 

src/or/addressmap.h

@@ -31,7 +31,7 @@ int parse_virtual_addr_network(const char *val, int validate_only,
                                char **msg);
 int client_dns_incr_failures(const char *address);
 void client_dns_clear_failures(const char *address);
-void client_dns_set_addressmap(origin_circuit_t *on_circ,
+void client_dns_set_addressmap(entry_connection_t *for_conn,
                                const char *address, const tor_addr_t *val,
                                const char *exitname, int ttl);
 const char *addressmap_register_virtual_address(int type, char *new_address);
@@ -39,7 +39,7 @@ void addressmap_get_mappings(smartlist_t *sl, time_t min_expires,
                              time_t max_expires, int want_expiry);
 int address_is_in_virtual_range(const char *addr);
 void clear_trackexithost_mappings(const char *exitname);
-void client_dns_set_reverse_addressmap(origin_circuit_t *on_circ,
+void client_dns_set_reverse_addressmap(entry_connection_t *for_conn,
                                        const char *address, const char *v,
                                        const char *exitname, int ttl);
 

src/or/connection_edge.c

@@ -2072,7 +2072,7 @@ connection_ap_handshake_socks_resolved(entry_connection_t *conn,
       tor_addr_t a;
       tor_addr_from_ipv4n(&a, get_uint32(answer));
       if (! tor_addr_is_null(&a)) {
-        client_dns_set_addressmap(origin_circ,
+        client_dns_set_addressmap(conn,
                                   conn->socks_request->address, &a,
                                   conn->chosen_exit_name, ttl);
       }
@@ -2080,13 +2080,13 @@ connection_ap_handshake_socks_resolved(entry_connection_t *conn,
       tor_addr_t a;
       tor_addr_from_ipv6_bytes(&a, (char*)answer);
       if (! tor_addr_is_null(&a)) {
-        client_dns_set_addressmap(origin_circ,
+        client_dns_set_addressmap(conn,
                                   conn->socks_request->address, &a,
                                   conn->chosen_exit_name, ttl);
       }
     } else if (answer_type == RESOLVED_TYPE_HOSTNAME && answer_len < 256) {
       char *cp = tor_strndup((char*)answer, answer_len);
-      client_dns_set_reverse_addressmap(origin_circ,
+      client_dns_set_reverse_addressmap(conn,
                                         conn->socks_request->address,
                                         cp,
                                         conn->chosen_exit_name, ttl);

src/or/relay.c

@@ -742,7 +742,7 @@ connection_ap_process_end_not_open(
             return 0;
           }
 
-          client_dns_set_addressmap(circ,
+          client_dns_set_addressmap(conn,
                                     conn->socks_request->address, &addr,
                                     conn->chosen_exit_name, ttl);
         }
@@ -979,7 +979,7 @@ connection_edge_process_relay_cell_not_open(
         return 0;
       }
 
-      client_dns_set_addressmap(TO_ORIGIN_CIRCUIT(circ),
+      client_dns_set_addressmap(entry_conn,
                                 entry_conn->socks_request->address, &addr,
                                 entry_conn->chosen_exit_name, ttl);