Use fascist_firewall_choose_address_ls() in hs_get_extend_info_from_lspecs()

changes/bug23588

@@ -0,0 +1,7 @@
+  o Minor bugfixes (address selection):
+    - Introduce fascist_firewall_choose_address_ls() which chooses an
+      IPv6 or IPv4 address based on a smartlist of link specifiers of
+      what is available and what we prefer. We use this function in
+      hs_get_extend_info_from_lspecs(). Fixes bug 23588; bugfix on
+      0.3.5.1-alpha. Patch by Neel Chauhan.
+

src/core/or/policies.c

@@ -1017,17 +1017,26 @@ fascist_firewall_choose_address_rs(const routerstatus_t *rs,
 }
 
 /** Like fascist_firewall_choose_address_base(), but takes in a smartlist
- * <b>lspecs</b> consisting of one or more link specifiers.
+ * <b>lspecs</b> consisting of one or more link specifiers. We assume
+ * fw_connection is FIREWALL_OR_CONNECTION as link specifiers cannot
+ * contain DirPorts.
  */
 void
 fascist_firewall_choose_address_ls(const smartlist_t *lspecs,
-                                   int pref_only, tor_addr_port_t* ap,
-                                   int direct_conn)
+                                   int pref_only, tor_addr_port_t* ap)
 {
   int have_v4 = 0, have_v6 = 0;
   uint16_t port_v4 = 0, port_v6 = 0;
   tor_addr_t addr_v4, addr_v6;
 
+  tor_assert(ap);
+
+  tor_addr_make_null(&ap->addr, AF_UNSPEC);
+  ap->port = 0;
+
+  tor_addr_make_null(&addr_v4, AF_INET);
+  tor_addr_make_null(&addr_v6, AF_INET6);
+
   SMARTLIST_FOREACH_BEGIN(lspecs, const link_specifier_t *, ls) {
     switch (link_specifier_get_ls_type(ls)) {
     case LS_IPV4:
@@ -1041,7 +1050,7 @@ fascist_firewall_choose_address_ls(const smartlist_t *lspecs,
     case LS_IPV6:
       /* Skip if we already seen a v6, or deliberately skip it if we're not a
        * direct connection. */
-      if (have_v6 || !direct_conn) continue;
+      if (have_v6) continue;
       tor_addr_from_ipv6_bytes(&addr_v6,
           (const char *) link_specifier_getconstarray_un_ipv6_addr(ls));
       port_v6 = link_specifier_get_un_ipv6_port(ls);
@@ -1053,11 +1062,6 @@ fascist_firewall_choose_address_ls(const smartlist_t *lspecs,
     }
   } SMARTLIST_FOREACH_END(ls);
 
-  tor_assert(ap);
-
-  tor_addr_make_null(&ap->addr, AF_UNSPEC);
-  ap->port = 0;
-
   /* Here, don't check for DirPorts as link specifiers are only used for
    * ORPorts. */
   const or_options_t *options = get_options();

src/core/or/policies.h

@@ -93,8 +93,7 @@ void fascist_firewall_choose_address_rs(const routerstatus_t *rs,
                                         firewall_connection_t fw_connection,
                                         int pref_only, tor_addr_port_t* ap);
 void fascist_firewall_choose_address_ls(const smartlist_t *lspecs,
-                                        int pref_only, tor_addr_port_t* ap,
-                                        int direct_conn);
+                                        int pref_only, tor_addr_port_t* ap);
 void fascist_firewall_choose_address_node(const node_t *node,
                                           firewall_connection_t fw_connection,
                                           int pref_only, tor_addr_port_t* ap);

src/feature/hs/hs_common.c

@@ -1672,14 +1672,16 @@ hs_pick_hsdir(smartlist_t *responsible_dirs, const char *req_key_str,
   return hs_dir;
 }
 
-/* From a list of link specifier, an onion key and if we are requesting a
- * direct connection (ex: single onion service), return a newly allocated
- * extend_info_t object. This function always returns an extend info with
- * an IPv4 address, or NULL.
+/* Given a list of link specifiers lspecs, a curve 25519 onion_key, and
+ * a direct connection boolean direct_conn (true for single onion services),
+ * return a newly allocated extend_info_t object.
+ *
+ * This function always returns an extend info with a valid IP address and
+ * ORPort, or NULL. If direct_conn is false, the IP address is always IPv4.
  *
  * It performs the following checks:
- *  if either IPv4 or legacy ID is missing, return NULL.
- *  if direct_conn, and we can't reach the IPv4 address, return NULL.
+ *  if there is no usable IP address, or legacy ID is missing, return NULL.
+ *  if direct_conn, and we can't reach any IP address, return NULL.
  */
 extend_info_t *
 hs_get_extend_info_from_lspecs(const smartlist_t *lspecs,
@@ -1688,10 +1690,12 @@ hs_get_extend_info_from_lspecs(const smartlist_t *lspecs,
 {
   int have_v4 = 0, have_legacy_id = 0, have_ed25519_id = 0;
   char legacy_id[DIGEST_LEN] = {0};
-  uint16_t port_v4 = 0;
-  tor_addr_t addr_v4;
   ed25519_public_key_t ed25519_pk;
   extend_info_t *info = NULL;
+  tor_addr_port_t ap;
+
+  tor_addr_make_null(&ap.addr, AF_UNSPEC);
+  ap.port = 0;
 
   tor_assert(lspecs);
 
@@ -1704,11 +1708,14 @@ hs_get_extend_info_from_lspecs(const smartlist_t *lspecs,
   SMARTLIST_FOREACH_BEGIN(lspecs, const link_specifier_t *, ls) {
     switch (link_specifier_get_ls_type(ls)) {
     case LS_IPV4:
-      /* Skip if we already seen a v4. */
-      if (have_v4) continue;
-      tor_addr_from_ipv4h(&addr_v4,
+      /* Skip if we already seen a v4. If direct_conn is true, we skip this
+       * block because fascist_firewall_choose_address_ls() will set ap. If
+       * direct_conn is false, set ap to the first IPv4 address and port in
+       * the link specifiers.*/
+      if (have_v4 || direct_conn) continue;
+      tor_addr_from_ipv4h(&ap.addr,
                           link_specifier_get_un_ipv4_addr(ls));
-      port_v4 = link_specifier_get_un_ipv4_port(ls);
+      ap.port = link_specifier_get_un_ipv4_port(ls);
       have_v4 = 1;
       break;
     case LS_LEGACY_ID:
@@ -1732,55 +1739,32 @@ hs_get_extend_info_from_lspecs(const smartlist_t *lspecs,
     }
   } SMARTLIST_FOREACH_END(ls);
 
-  /* Legacy ID is mandatory, and we require IPv4. */
-  if (!have_v4 || !have_legacy_id) {
-    bool both = !have_v4 && !have_legacy_id;
-    log_fn(LOG_PROTOCOL_WARN, LD_REND, "Missing %s%s%s link specifier%s.",
-           !have_v4 ? "IPv4" : "",
-           both ? " and " : "",
-           !have_legacy_id ? "legacy ID" : "",
-           both ? "s" : "");
+  /* Choose a preferred address first, but fall back to an allowed address. */
+  if (direct_conn)
+    fascist_firewall_choose_address_ls(lspecs, 0, &ap);
+
+  /* Legacy ID is mandatory, and we require an IP address. */
+  if (!tor_addr_port_is_valid_ap(&ap, 0) || !have_legacy_id) {
+    /* If we're missing the legacy ID or the IP address, return NULL. */
     goto done;
   }
 
-  /* We know we have IPv4, because we just checked. */
-  if (!direct_conn) {
-    /* All clients can extend to any IPv4 via a 3-hop path. */
-    goto validate;
-  } else if (direct_conn &&
-             fascist_firewall_allows_address_addr(&addr_v4, port_v4,
-                                                  FIREWALL_OR_CONNECTION,
-                                                  0, 0)) {
-    /* Direct connection and we can reach it in IPv4 so go for it. */
-    goto validate;
+  /* We will add support for falling back to a 3-hop path in a later
+   * release. */
 
-    /* We will add support for falling back to a 3-hop path in a later
-     * release. */
-  } else {
-    /* If we can't reach IPv4, return NULL. */
-    log_fn(LOG_PROTOCOL_WARN, LD_REND,
-           "Received an IPv4 link specifier, "
-           "but the address is not reachable: %s:%u",
-           fmt_addr(&addr_v4), port_v4);
-    goto done;
-  }
-
-  /* We will add support for IPv6 in a later release. */
-
- validate:
   /* We'll validate now that the address we've picked isn't a private one. If
    * it is, are we allowed to extend to private addresses? */
-  if (!extend_info_addr_is_allowed(&addr_v4)) {
+  if (!extend_info_addr_is_allowed(&ap.addr)) {
     log_fn(LOG_PROTOCOL_WARN, LD_REND,
            "Requested address is private and we are not allowed to extend to "
-           "it: %s:%u", fmt_addr(&addr_v4), port_v4);
+           "it: %s:%u", fmt_addr(&ap.addr), ap.port);
     goto done;
   }
 
   /* We do have everything for which we think we can connect successfully. */
   info = extend_info_new(NULL, legacy_id,
                          (have_ed25519_id) ? &ed25519_pk : NULL, NULL,
-                         onion_key, &addr_v4, port_v4);
+                         onion_key, &ap.addr, ap.port);
  done:
   return info;
 }