Log when IPv4/IPv6 restrictions or preferences weren't met

src/or/connection.c

@@ -19,6 +19,7 @@
  */
 #define TOR_CHANNEL_INTERNAL_
 #define CONNECTION_PRIVATE
+#include "backtrace.h"
 #include "channel.h"
 #include "channeltls.h"
 #include "circuitbuild.h"
@@ -1721,6 +1722,66 @@ connection_connect_sockaddr,(connection_t *conn,
   return inprogress ? 0 : 1;
 }
 
+/* Log a message if connection violates ClientUseIPv4 0 or ClientUseIPv6 0.
+ * Log a less severe message if we couldn't conform to ClientPreferIPv6ORPort
+ * or ClientPreferIPv6ORPort. */
+static void
+connection_connect_log_client_use_ip_version(const connection_t *conn)
+{
+  const or_options_t *options = get_options();
+
+  /* Only non-bridge clients care about ClientUseIPv4/6, bail out early on
+   * servers and bridge clients */
+  if (options->UseBridges || server_mode(options) || !conn
+      || conn->type == CONN_TYPE_EXIT) {
+    return;
+  }
+
+  /* We're only prepared to log OR and DIR connections here */
+  if (conn->type != CONN_TYPE_OR && conn->type != CONN_TYPE_DIR) {
+    return;
+  }
+
+  const int must_ipv4 = (options->ClientUseIPv6 == 0);
+  const int must_ipv6 = (options->ClientUseIPv4 == 0);
+  const int pref_ipv6 = (conn->type == CONN_TYPE_OR
+                         ? nodelist_prefer_ipv6_orport(options)
+                         : nodelist_prefer_ipv6_dirport(options));
+  tor_addr_t real_addr;
+  tor_addr_make_null(&real_addr, AF_UNSPEC);
+
+  /* OR conns keep the original address in real_addr, as addr gets overwritten
+   * with the descriptor address */
+  if (conn->type == CONN_TYPE_OR) {
+    const or_connection_t *or_conn = TO_OR_CONN((connection_t *)conn);
+    tor_addr_copy(&real_addr, &or_conn->real_addr);
+  } else if (conn->type == CONN_TYPE_DIR) {
+    tor_addr_copy(&real_addr, &conn->addr);
+  }
+
+  /* Check if we broke a mandatory address family restriction */
+  if ((must_ipv4 && tor_addr_family(&real_addr) == AF_INET6)
+      || (must_ipv6 && tor_addr_family(&real_addr) == AF_INET)) {
+    log_warn(LD_BUG, "%s connection to %s violated ClientUseIPv%s 0.",
+             conn->type == CONN_TYPE_OR ? "OR" : "Dir",
+             fmt_addr(&real_addr),
+             options->ClientUseIPv4 == 0 ? "4" : "6");
+    log_backtrace(LOG_WARN, LD_BUG, "Address came from");
+  }
+
+  /* Check if we couldn't satisfy an address family preference */
+  if ((!pref_ipv6 && tor_addr_family(&real_addr) == AF_INET6)
+      || (pref_ipv6 && tor_addr_family(&real_addr) == AF_INET)) {
+    log_info(LD_NET, "Connection to %s doesn't satisfy ClientPreferIPv6%sPort "
+             "%d, with ClientUseIPv4 %d and ClientUseIPv6 %d.",
+             fmt_addr(&real_addr),
+             conn->type == CONN_TYPE_OR ? "OR" : "Dir",
+             conn->type == CONN_TYPE_OR ? options->ClientPreferIPv6ORPort
+                                        : options->ClientPreferIPv6DirPort,
+             options->ClientUseIPv4, options->ClientUseIPv4);
+  }
+}
+
 /** Take conn, make a nonblocking socket; try to connect to
  * addr:port (port arrives in *host order*). If fail, return -1 and if
  * applicable put your best guess about errno into *<b>socket_error</b>.
@@ -1745,6 +1806,10 @@ connection_connect(connection_t *conn, const char *address,
   const or_options_t *options = get_options();
   int protocol_family;
 
+  /* Log if we didn't stick to ClientUseIPv4/6 or ClientPreferIPv6OR/DirPort
+   */
+  connection_connect_log_client_use_ip_version(conn);
+
   if (tor_addr_family(addr) == AF_INET6)
     protocol_family = PF_INET6;
   else

src/or/directory.c

@@ -4,6 +4,7 @@
 /* See LICENSE for licensing information */
 
 #include "or.h"
+#include "backtrace.h"
 #include "buffers.h"
 #include "circuitbuild.h"
 #include "config.h"
@@ -692,11 +693,13 @@ directory_initiate_command_routerstatus_rend(const routerstatus_t *status,
 
   /* We rejected both addresses. This isn't great. */
   if (!have_or && !have_dir) {
-    log_info(LD_DIR, "Rejected both the OR and Dir address when launching a "
+    log_warn(LD_BUG, "Rejected all OR and Dir addresses from %s when "
-             "directory connection to: IPv4 %s OR %d Dir %d IPv6 %s OR %d "
+             "launching a directory connection to: IPv4 %s OR %d Dir %d "
-             "Dir %d", fmt_addr32(status->addr), status->or_port,
+             "IPv6 %s OR %d Dir %d", routerstatus_describe(status),
+             fmt_addr32(status->addr), status->or_port,
              status->dir_port, fmt_addr(&status->ipv6_addr),
              status->ipv6_orport, status->dir_port);
+    log_backtrace(LOG_WARN, LD_BUG, "Addresses came from");
     return;
   }
 
@@ -1050,10 +1053,13 @@ directory_initiate_command_rend(const tor_addr_port_t *or_addr_port,
   if (or_connection && (!or_addr_port->port
                         || tor_addr_is_null(&or_addr_port->addr))) {
     log_warn(LD_DIR, "Cannot make an OR connection without an OR port.");
+    log_backtrace(LOG_WARN, LD_BUG, "Address came from");
     return;
   } else if (!or_connection && (!dir_addr_port->port
                                 || tor_addr_is_null(&dir_addr_port->addr))) {
     log_warn(LD_DIR, "Cannot make a Dir connection without a Dir port.");
+    log_backtrace(LOG_WARN, LD_BUG, "Address came from");
+
     return;
   }
 

src/or/routerlist.c

@@ -13,6 +13,7 @@
 
 #define ROUTERLIST_PRIVATE
 #include "or.h"
+#include "backtrace.h"
 #include "crypto_ed25519.h"
 #include "circuitstats.h"
 #include "config.h"
@@ -1536,6 +1537,50 @@ router_is_already_dir_fetching_rs(const routerstatus_t *rs,
        || router_is_already_dir_fetching(&ipv6_dir_ap, serverdesc, microdesc));
 }
 
+#ifndef LOG_FALSE_POSITIVES_DURING_BOOTSTRAP
+#define LOG_FALSE_POSITIVES_DURING_BOOTSTRAP 0
+#endif
+
+/* Log a message if rs is not found or not a preferred address */
+static void
+router_picked_poor_directory_log(const routerstatus_t *rs)
+{
+  const networkstatus_t *usable_consensus;
+  usable_consensus = networkstatus_get_reasonably_live_consensus(time(NULL),
+                                                 usable_consensus_flavor());
+
+#if !LOG_FALSE_POSITIVES_DURING_BOOTSTRAP
+  /* Don't log early in the bootstrap process, it's normal to pick from a
+   * small pool of nodes. Of course, this won't help if we're trying to
+   * diagnose bootstrap issues. */
+  if (!smartlist_len(nodelist_get_list()) || !usable_consensus
+      || !router_have_minimum_dir_info()) {
+    return;
+  }
+#endif
+
+  /* We couldn't find a node, or the one we have doesn't fit our preferences.
+   * This might be a bug. */
+  if (!rs) {
+    log_warn(LD_BUG, "Firewall denied all OR and Dir addresses for all relays "
+             "when searching for a directory.");
+    log_backtrace(LOG_WARN, LD_BUG, "Node search initiated by");
+  } else if (!fascist_firewall_allows_rs(rs, FIREWALL_OR_CONNECTION, 1)
+             && !fascist_firewall_allows_rs(rs, FIREWALL_DIR_CONNECTION, 1)
+             ) {
+    log_warn(LD_BUG, "Selected a directory %s with non-preferred OR and Dir "
+             "addresses for launching a connection: "
+             "IPv4 %s OR %d Dir %d IPv6 %s OR %d Dir %d",
+             routerstatus_describe(rs),
+             fmt_addr32(rs->addr), rs->or_port,
+             rs->dir_port, fmt_addr(&rs->ipv6_addr),
+             rs->ipv6_orport, rs->dir_port);
+    log_backtrace(LOG_WARN, LD_BUG, "Node search initiated by");
+  }
+}
+
+#undef LOG_FALSE_POSITIVES_DURING_BOOTSTRAP
+
 /** How long do we avoid using a directory server after it's given us a 503? */
 #define DIR_503_TIMEOUT (60*60)
 
@@ -1711,6 +1756,8 @@ router_pick_directory_server_impl(dirinfo_type_t type, int flags,
   if (n_busy_out)
     *n_busy_out = n_busy;
 
+  router_picked_poor_directory_log(result ? result->rs : NULL);
+
   return result ? result->rs : NULL;
 }
 
@@ -1843,6 +1890,8 @@ router_pick_trusteddirserver_impl(const smartlist_t *sourcelist,
 
   RETRY_WITHOUT_EXCLUDE(retry_search);
 
+  router_picked_poor_directory_log(result);
+
   if (n_busy_out)
     *n_busy_out = n_busy;
   return result;