1 files changed, 218 insertions, 45 deletions

diff --git a/src/or/nodelist.c b/src/or/nodelist.c
index a1d99e9899..7ca1146e86 100644
--- a/src/or/nodelist.c
+++ b/src/or/nodelist.c
@@ -214,6 +214,76 @@ nodelist_add_microdesc(microdesc_t *md)
   return node;
 }
 
+/** Do we prefer to connect to IPv6, ignoring ClientPreferIPv6ORPort and
+ * ClientPreferIPv6DirPort?
+ * If we're unsure, return -1, otherwise, return 1 for IPv6 and 0 for IPv4.
+ */
+static int
+nodelist_prefer_ipv6(const or_options_t *options)
+{
+  /*
+   Cheap implementation of config options ClientUseIPv4 & ClientUseIPv6 --
+   If we're a server, use IPv4.
+   If we're a client running with bridges, use IPv6.
+   Otherwise, use IPv6 if we can and it's preferred, or if IPv4 is disabled.
+   See #4455 and #17840 for more on this subject.
+   */
+
+  /* Servers prefer IPv4 */
+  if (server_mode(options)) {
+    return 0;
+  }
+
+  /* Bridge clients prefer IPv6 */
+  if (options->UseBridges) {
+    return 1;
+  }
+
+  if (!options->ClientUseIPv4) {
+    return 1;
+  }
+
+  return -1;
+}
+
+/** Do we prefer to connect to IPv6 ORPorts?
+ */
+int
+nodelist_prefer_ipv6_orport(const or_options_t *options)
+{
+  int pref_ipv6 = nodelist_prefer_ipv6(options);
+
+  if (pref_ipv6 >= 0) {
+    return pref_ipv6;
+  }
+
+  /* We prefer IPv6 ORPorts if the option is set */
+  if (options->ClientUseIPv6 && options->ClientPreferIPv6ORPort) {
+    return 1;
+  }
+
+  return 0;
+}
+
+/** Do we prefer to connect to IPv6 DirPorts?
+ */
+int
+nodelist_prefer_ipv6_dirport(const or_options_t *options)
+{
+  int pref_ipv6 = nodelist_prefer_ipv6(options);
+
+  if (pref_ipv6 >= 0) {
+    return pref_ipv6;
+  }
+
+  /* We prefer IPv6 DirPorts if the option is set */
+  if (options->ClientUseIPv6 && options->ClientPreferIPv6DirPort) {
+    return 1;
+  }
+
+  return 0;
+}
+
 /** Tell the nodelist that the current usable consensus is <b>ns</b>.
  * This makes the nodelist change all of the routerstatus entries for
  * the nodes, drop nodes that no longer have enough info to get used,
@@ -224,7 +294,6 @@ nodelist_set_consensus(networkstatus_t *ns)
 {
   const or_options_t *options = get_options();
   int authdir = authdir_mode_v3(options);
-  int client = !server_mode(options);
 
   init_nodelist();
   if (ns->flavor == FLAV_MICRODESC)
@@ -261,7 +330,7 @@ nodelist_set_consensus(networkstatus_t *ns)
       node->is_bad_exit = rs->is_bad_exit;
       node->is_hs_dir = rs->is_hs_dir;
       node->ipv6_preferred = 0;
-      if (client && options->ClientPreferIPv6ORPort == 1 &&
+      if (nodelist_prefer_ipv6_orport(options) &&
           (tor_addr_is_null(&rs->ipv6_addr) == 0 ||
            (node->md && tor_addr_is_null(&node->md->ipv6_addr) == 0)))
         node->ipv6_preferred = 1;
@@ -925,30 +994,60 @@ node_get_declared_family(const node_t *node)
     return NULL;
 }
 
+/* Does this node have a valid IPv6 address? */
+static int
+node_has_ipv6_addr(const node_t *node)
+{
+  if (node->ri)
+    return !tor_addr_is_null(&node->ri->ipv6_addr);
+  if (node->md)
+    return !tor_addr_is_null(&node->md->ipv6_addr);
+  if (node->rs)
+    return !tor_addr_is_null(&node->rs->ipv6_addr);
+
+  return 0;
+}
+
 /** Return 1 if we prefer the IPv6 address and OR TCP port of
  * <b>node</b>, else 0.
  *
- *  We prefer the IPv6 address if the router has an IPv6 address and
+ *  We prefer the IPv6 address if the router has an IPv6 address,
+ *  and we can use IPv6 addresses, and:
  *  i) the node_t says that it prefers IPv6
  *  or
- *  ii) the router has no IPv4 address. */
+ *  ii) the router has no IPv4 OR address.
+ *  or
+ *  iii) our preference is for IPv6 addresses.
+ *  (This extra step is needed in case our preferences have changed since
+ *  node->ipv6_preferred was set at the time the consensus was loaded.)
+ */
 int
-node_ipv6_preferred(const node_t *node)
+node_ipv6_or_preferred(const node_t *node)
 {
+  const or_options_t *options = get_options();
   tor_addr_port_t ipv4_addr;
   node_assert_ok(node);
 
-  if (node->ipv6_preferred || node_get_prim_orport(node, &ipv4_addr)) {
-    if (node->ri)
-      return !tor_addr_is_null(&node->ri->ipv6_addr);
-    if (node->md)
-      return !tor_addr_is_null(&node->md->ipv6_addr);
-    if (node->rs)
-      return !tor_addr_is_null(&node->rs->ipv6_addr);
+  if (!options->ClientUseIPv6) {
+    return 0;
+  } else if (node->ipv6_preferred || node_get_prim_orport(node, &ipv4_addr)
+      || nodelist_prefer_ipv6_orport(get_options())) {
+    return node_has_ipv6_addr(node);
   }
   return 0;
 }
 
+#define RETURN_IPV4_AP(r, port_field, ap_out) \
+  STMT_BEGIN \
+    if (r) { \
+      if ((r)->addr == 0 || (r)->port_field == 0) \
+        return -1; \
+      tor_addr_from_ipv4h(&(ap_out)->addr, (r)->addr); \
+      (ap_out)->port = (r)->port_field; \
+      return 0; \
+    } \
+  STMT_END
+
 /** Copy the primary (IPv4) OR port (IP address and TCP port) for
  * <b>node</b> into *<b>ap_out</b>. Return 0 if a valid address and
  * port was copied, else return non-zero.*/
@@ -958,20 +1057,10 @@ node_get_prim_orport(const node_t *node, tor_addr_port_t *ap_out)
   node_assert_ok(node);
   tor_assert(ap_out);
 
-  if (node->ri) {
-    if (node->ri->addr == 0 || node->ri->or_port == 0)
-      return -1;
-    tor_addr_from_ipv4h(&ap_out->addr, node->ri->addr);
-    ap_out->port = node->ri->or_port;
-    return 0;
-  }
-  if (node->rs) {
-    if (node->rs->addr == 0 || node->rs->or_port == 0)
-      return -1;
-    tor_addr_from_ipv4h(&ap_out->addr, node->rs->addr);
-    ap_out->port = node->rs->or_port;
-    return 0;
-  }
+  RETURN_IPV4_AP(node->ri, or_port, ap_out);
+  RETURN_IPV4_AP(node->rs, or_port, ap_out);
+  /* Microdescriptors only have an IPv6 address */
+
   return -1;
 }
 
@@ -980,21 +1069,12 @@ node_get_prim_orport(const node_t *node, tor_addr_port_t *ap_out)
 void
 node_get_pref_orport(const node_t *node, tor_addr_port_t *ap_out)
 {
-  const or_options_t *options = get_options();
   tor_assert(ap_out);
 
-  /* Cheap implementation of config option ClientUseIPv6 -- simply
-     don't prefer IPv6 when ClientUseIPv6 is not set and we're not a
-     client running with bridges. See #4455 for more on this subject.
-
-     Note that this filter is too strict since we're hindering not
-     only clients! Erring on the safe side shouldn't be a problem
-     though. XXX move this check to where outgoing connections are
-     made? -LN */
-  if ((options->ClientUseIPv6 || options->UseBridges) &&
-      node_ipv6_preferred(node)) {
+  if (node_ipv6_or_preferred(node)) {
     node_get_pref_ipv6_orport(node, ap_out);
   } else {
+    /* the primary ORPort is always on IPv4 */
     node_get_prim_orport(node, ap_out);
   }
 }
@@ -1007,20 +1087,113 @@ node_get_pref_ipv6_orport(const node_t *node, tor_addr_port_t *ap_out)
   node_assert_ok(node);
   tor_assert(ap_out);
 
-  /* We prefer the microdesc over a potential routerstatus here. They
-     are not being synchronised atm so there might be a chance that
-     they differ at some point, f.ex. when flipping
-     UseMicrodescriptors? -LN */
+  /* Prefer routerstatus over microdesc for consistency with the
+   * fascist_firewall_* functions. Also check if the address or port are valid,
+   * and try another alternative if they are not. */
 
-  if (node->ri) {
+  if (node->ri && node->ri->ipv6_orport
+      && !tor_addr_is_null(&node->ri->ipv6_addr)) {
     tor_addr_copy(&ap_out->addr, &node->ri->ipv6_addr);
     ap_out->port = node->ri->ipv6_orport;
-  } else if (node->md) {
+  } else if (node->rs && node->rs->ipv6_orport
+             && !tor_addr_is_null(&node->rs->ipv6_addr)) {
+    tor_addr_copy(&ap_out->addr, &node->rs->ipv6_addr);
+    ap_out->port = node->rs->ipv6_orport;
+  } else if (node->md && node->md->ipv6_orport
+             && !tor_addr_is_null(&node->md->ipv6_addr)) {
     tor_addr_copy(&ap_out->addr, &node->md->ipv6_addr);
     ap_out->port = node->md->ipv6_orport;
-  } else if (node->rs) {
+  } else {
+    tor_addr_make_null(&ap_out->addr, AF_INET6);
+    ap_out->port = 0;
+  }
+}
+
+/** Return 1 if we prefer the IPv6 address and Dir TCP port of
+ * <b>node</b>, else 0.
+ *
+ *  We prefer the IPv6 address if the router has an IPv6 address,
+ *  and we can use IPv6 addresses, and:
+ *  i) the node_t says that it prefers IPv6
+ *  or
+ *  ii) the router has no IPv4 Dir address.
+ *  or
+ *  iii) our preference is for IPv6 addresses.
+ *  (This extra step is needed in case our preferences have changed since
+ *  node->ipv6_preferred was set at the time the consensus was loaded.)
+ */
+int
+node_ipv6_dir_preferred(const node_t *node)
+{
+  const or_options_t *options = get_options();
+  tor_addr_port_t ipv4_addr;
+  node_assert_ok(node);
+
+  if (!options->ClientUseIPv6) {
+    return 0;
+  } else if (node->ipv6_preferred || node_get_prim_dirport(node, &ipv4_addr)
+      || nodelist_prefer_ipv6_dirport(get_options())) {
+    return node_has_ipv6_addr(node);
+  }
+  return 0;
+}
+
+/** Copy the primary (IPv4) Dir port (IP address and TCP port) for
+ * <b>node</b> into *<b>ap_out</b>. Return 0 if a valid address and
+ * port was copied, else return non-zero.*/
+int
+node_get_prim_dirport(const node_t *node, tor_addr_port_t *ap_out)
+{
+  node_assert_ok(node);
+  tor_assert(ap_out);
+
+  RETURN_IPV4_AP(node->ri, dir_port, ap_out);
+  RETURN_IPV4_AP(node->rs, dir_port, ap_out);
+  /* Microdescriptors only have an IPv6 address */
+
+  return -1;
+}
+
+#undef RETURN_IPV4_AP
+
+/** Copy the preferred Dir port (IP address and TCP port) for
+ * <b>node</b> into *<b>ap_out</b>.  */
+void
+node_get_pref_dirport(const node_t *node, tor_addr_port_t *ap_out)
+{
+  tor_assert(ap_out);
+
+  if (node_ipv6_dir_preferred(node)) {
+    node_get_pref_ipv6_dirport(node, ap_out);
+  } else {
+    /* the primary DirPort is always on IPv4 */
+    node_get_prim_dirport(node, ap_out);
+  }
+}
+
+/** Copy the preferred IPv6 Dir port (IP address and TCP port) for
+ * <b>node</b> into *<b>ap_out</b>. */
+void
+node_get_pref_ipv6_dirport(const node_t *node, tor_addr_port_t *ap_out)
+{
+  node_assert_ok(node);
+  tor_assert(ap_out);
+
+  /* Check if the address or port are valid, and try another alternative if
+   * they are not. Note that microdescriptors have no dir_port. */
+
+  /* Assume IPv4 and IPv6 dirports are the same */
+  if (node->ri && node->ri->dir_port
+      && !tor_addr_is_null(&node->ri->ipv6_addr)) {
+    tor_addr_copy(&ap_out->addr, &node->ri->ipv6_addr);
+    ap_out->port = node->ri->dir_port;
+  } else if (node->rs && node->rs->dir_port
+             && !tor_addr_is_null(&node->rs->ipv6_addr)) {
     tor_addr_copy(&ap_out->addr, &node->rs->ipv6_addr);
-    ap_out->port = node->rs->ipv6_orport;
+    ap_out->port = node->rs->dir_port;
+  } else {
+    tor_addr_make_null(&ap_out->addr, AF_INET6);
+    ap_out->port = 0;
   }
 }