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

1 files changed, 65 insertions, 0 deletions

diff --git a/src/or/connection.c b/src/or/connection.c
index d59e07bdbe..f252d2faa1 100644
--- a/src/or/connection.c
+++ b/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